American Journal Of Physiology. Cell Physiology[JOURNAL]
Sun
200 papers
Correction for Xu et al., volume 328, 2024, p. C1076-C1089.
Am J Physiol Cell Physiol · 2026 May · PMID 42090301 · Publisher ↗
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Fluid restriction enhances mitochondrial stress in peripheral blood mononuclear cells following high-volume resistance exercise in health young males.
Luk HY, Appell CR, Jiwan NC … +3 more , Vellers HL, Sekiguchi Y, Levitt DE
Am J Physiol Cell Physiol · 2026 Jun · PMID 42089800 · Publisher ↗
Exercising under dehydrated conditions is common among physically active individuals, yet its impact on immune cell mitochondrial quality control, oxidative stress and inflammatory signaling, and systemic inflammatory me...
Exercising under dehydrated conditions is common among physically active individuals, yet its impact on immune cell mitochondrial quality control, oxidative stress and inflammatory signaling, and systemic inflammatory mediators remains poorly defined. This study investigated mitochondrial quality control and systemic inflammatory responses to high-volume resistance exercise (HVRE) under hydrated (HYD) and dehydrated (DEH) conditions in 10 young men (21 ± 1 yr, 175 ± 6 cm, 76.9 ± 10.5 kg, 18.5 ± 6.3% fat). Participants completed two identical HVRE sessions following either normal hydration or 24-h fluid restriction. Peripheral blood mononuclear cells (PBMCs) collected before (PRE) and at 1 h and 3 h post-HVRE were analyzed for proteins related to mitochondrial quality control (PINK1, Parkin, DRP1, p-DRP1, and MFN2), oxidative stress and inflammatory signaling (p-NF-κB, NF-κB, SOD2, and HO), autophagy machinery and degradation (LC3-I, LC3-II, p62, and cathepsin-L), and blood samples for systemic inflammatory mediators (IL-6, TNF-α, CRP, and HO). Significant time × condition interaction effects revealed that LC3-II/I was greater in DEH than HYD at PRE and 3 h. In DEH, LC3-II/I returned to PRE levels at 3 h, whereas in HYD, it was greatest at 3 h. PINK1 was greater at 1 h and 3 h, and pDRP1 was greater at 3 h in DEH than HYD. Also, PINK1 and pDRP1 were greatest at 3 h post-HVRE in DEH. Lastly, significant condition main effects revealed greater MFN2, p62, LC3-II, and HO in PBMCs and greater IL-6 and CRP in serum in DEH than in HYD. These results provide novel evidence that 24 h of fluid restriction before metabolically demanding resistance exercise activates mitochondrial quality control in PBMCs and elevates systemic inflammatory mediators. This study examined how 24-h fluid restriction affects mitochondrial stress and inflammatory responses in peripheral blood mononuclear cells (PBMCs) after high-volume resistance exercise in young men. Dehydration increased markers of mitophagy (PINK1 and p-DRP1), autophagosome formation (LC3-II and p62), and oxidative stress (HO), while systemic IL-6 and CRP were elevated compared with euhydration. Findings suggest dehydration amplifies mitochondrial stress and proinflammatory signaling, highlighting the importance of proper hydration during exercise and its implications on cellular homeostasis.
Identifying quiescent satellite cells: a scoping review of transcriptomic markers and limitations.
Syroid AL, Steele AP, Murach KA … +1 more , Hawke TJ
Am J Physiol Cell Physiol · 2026 Jun · PMID 42089570 · Publisher ↗
Skeletal muscle regeneration relies on the resident stem cell population, termed satellite cells. Mechanistically, understanding the quiescence and activation dynamics of muscle satellite cells is essential for regenerat...
Skeletal muscle regeneration relies on the resident stem cell population, termed satellite cells. Mechanistically, understanding the quiescence and activation dynamics of muscle satellite cells is essential for regenerative therapies and emerging applications such as cellular agriculture. Quiescent satellite cells (QSCs) are typically identified by expression of paired box 7 (PAX7) and functional characteristics, including a lack of proliferation. However, with the rapidly growing body of transcriptomic data, there is a lack of consensus regarding what markers can be used to identify quiescent satellite cells across transcriptomic studies. The purpose of this review was to evaluate the transcripts currently used to identify QSCs using transcriptomics and to establish an evidence-based foundation that could be used for future analyses. After surveying published single-cell transcriptomic studies, we identified and/or myogenic factor 5 () as the most used markers of general satellite cell identity, whereas sprouty RTK signaling antagonist 1 (), cluster of differentiation 34 (), and calcitonin receptor (), together with the absence of myogenic differentiation 1 (), marker of proliferation Kiel 67 (), and cyclin-dependent kinase 1 (), were most commonly used to identify QSC clusters in murine studies. In contrast, there is currently insufficient literature to make a confident conclusion on quiescence markers in larger mammals, including humans, pigs, and cattle. We also highlight the conceptual and technical challenges associated with transcriptomic analysis of satellite cell subpopulations, including continuum-based cell states, isolation-induced transcriptional changes, and inconsistent terminology. As a field, greater consistency in language, standardized analyses, and cross-species validation will be required to progress the study of satellite cell quiescence and its translational utility.
Ribosome dynamics during skeletal muscle repair and regeneration in mice and humans.
Cui M, Edman S, Jude B … +13 more , Jannig PR, Horwath O, Shorter E, Koopmans PJ, Chambers TL, Jones RG, Nilsson A, Lanner JT, Sejersen T, Pontén E, Murach KA, Schilcher J, von Walden F
Am J Physiol Cell Physiol · 2026 Jul · PMID 42065367 · Publisher ↗
Skeletal muscle repair requires coordinated regulation of inflammation and protein synthesis, but the roles of ribosome biogenesis and protein composition remain poorly defined. To address this, mice underwent femoral ar...
Skeletal muscle repair requires coordinated regulation of inflammation and protein synthesis, but the roles of ribosome biogenesis and protein composition remain poorly defined. To address this, mice underwent femoral artery ligation (FAL) to induce muscle regeneration over 28 days. In humans, tibialis anterior biopsies from patients with traumatic tibial fracture were subjected to RNA sequencing. Following FAL, c mRNA increased transiently, followed by increased ribosomal DNA transcription, leading to elevated total RNA levels. Skeletal muscle-specific ribosomal protein paralog RPL3L was replaced by the ubiquitously expressed RPL3 during the initial phases of recovery, but this shift was reversed by . A substantial transcriptomic response was observed in human muscle injury, with heavy emphasis on MYC-induced anabolism and inflammation. This supports a model in which MYC-driven changes in ribosomal content and composition form a core anabolic module in skeletal muscle repair, potentially representing a targetable axis to enhance recovery after muscle injury. Our findings establish ribosome biogenesis and ribosome remodeling as core components of the skeletal muscle regenerative program conserved across species. The rapid, MYC-driven induction of translational capacity, coupled with a transient switch in ribosomal protein composition, increases ribosome heterogeneity during skeletal muscle regeneration.
Single cell analysis of muscle contracture in cerebral palsy reveals profibrotic and antimyogenic stem cell populations with altered cell-cell interactions.
Stewart MW, Hu LY, Loomis T … +8 more , Brashear SE, De La Torre LM, Sulthan AM, Villalba M, Davids JR, Wang Y, Kulkarni VA, Smith LR
Am J Physiol Cell Physiol · 2026 Jul · PMID 42021719 · Full text
Development of muscle contractures is common in cerebral palsy (CP) and is characterized by high muscle stiffness that limits function and mobility. However, the state of stem cells within contracture, particularly muscl...
Development of muscle contractures is common in cerebral palsy (CP) and is characterized by high muscle stiffness that limits function and mobility. However, the state of stem cells within contracture, particularly muscle stem cells and fibroadipogenic progenitors, is largely unknown. This study leverages single cell RNA sequencing technology to determine how specific cell types are altered in the contracture environment. Skeletal muscle biopsies were collected from children with CP or typically developing (TD) children undergoing surgery. The 10X Genomics platform was used on tissue from = 3 patients per condition. Significant changes in CP compared to TD were investigated within individual cell types for differentially expressed genes, gene ontologies, cell subpopulations, and predicted interactions. CP muscle stem cells demonstrated significant upregulation of fibrotic genes and downregulation of myogenic genes compared to typically developing. Fibroadipogenic progenitors in CP showed the emergence of a significant proportion of a highly profibrotic subpopulation, leading to the most dramatically upregulated genes in CP also being extracellular matrix constituents. Interacting signals between fibroadipogenic progenitors, muscle stem cells, and immune cells were identified that support contracture progression. Contracture is associated with reduced myogenic transcriptional features in muscle stem cells and enhances fibrotic signals in muscle stem cells and fibroadipogenic progenitors that perpetuate contracture. The study reveals specific genes and signaling pathways as therapeutic targets to reduce muscle contracture in children with CP. The development of skeletal muscle contractures in cerebral palsy is a major component of disability. However, little is known about how contracture influences stem cells. This study is the first to apply single cell RNA sequencing technology to muscle contractures of children with cerebral palsy. The analysis reveals muscle stem cells with reduced myogenic transcription. Critically, a profibrotic subpopulation of fibroadipogenic progenitors is revealed in contracture. Additionally, cell-cell signaling analysis identifies potential therapeutic targets.
β-Hydroxybutyrate attenuates bronchial smooth muscle proinflammatory cytokine production and contraction.
Fastiggi VA, Mank MM, Caporizzo MA … +1 more , Poynter ME
Am J Physiol Cell Physiol · 2026 Jun · PMID 42021684 · Full text
Asthma is a chronic respiratory condition characterized by airway inflammation, remodeling, and hyperresponsiveness to triggers that lead to airway constriction and impaired airflow. Bronchial smooth muscle (BSM) plays a...
Asthma is a chronic respiratory condition characterized by airway inflammation, remodeling, and hyperresponsiveness to triggers that lead to airway constriction and impaired airflow. Bronchial smooth muscle (BSM) plays a central role in these processes by constricting the airways and producing proinflammatory cytokines in response to environmental triggers, allergens, and cytokines. Although current therapies, including bronchodilators, corticosteroids, and biologics, effectively treat many patients, additional strategies are needed for difficult-to-treat asthma. Emerging evidence suggests that therapeutic ketosis, achieved through dietary interventions or exogenous ketone supplementation, may reduce airway hyperresponsiveness and inflammation. Classically known as metabolic fuels, ketone bodies also signal through cell-surface receptors and transporters to elicit their activities. Increased ketone body levels in vivo, such as during weight loss or caloric restriction, correlate with improved asthma symptoms, reduced oxidative stress, and decreased inflammation. Here, we investigated the predominant ketone body, β-hydroxybutyrate (BHB), as a potential modulator of BSM function. Using human bronchial smooth muscle cells in vitro, we found that BHB suppresses IL-1β-induced proinflammatory cytokine production and attenuates histamine-induced contraction through a mechanism involving activation of the free fatty acid receptor 3 (FFAR3). In mouse precision-cut lung slices (PCLS) ex vivo, we demonstrated that both BHB and an FFAR3 agonist reduce histamine-induced airway narrowing and epithelial cellular extrusion. Collectively, these findings identify BSM and FFAR3 as cellular targets of therapeutic ketosis and support BHB as a potential beneficial agent for mitigating inflammation and bronchoconstriction in asthma. Asthma is characterized by airway inflammation and bronchoconstriction, with aberrant bronchial smooth muscle function contributing to disease severity. Therapeutic ketosis, achieved through a ketogenic diet or exogenous ketone supplementation, attenuates airway inflammation and bronchial hyperresponsiveness. Using bronchial smooth muscle cells and precision-cut lung slices, we demonstrate that the ketone body β-hydroxybutyrate (BHB) suppresses IL-1β-induced proinflammatory cytokine production and histamine-evoked bronchoconstriction via activation of the free fatty acid receptor FFAR3.
Sequential invasion assays identify carbonic anhydrase IX as a driver of invasiveness in epithelial triple-negative breast cancer cells.
Black PJ, Ball DD, Edwards AD … +7 more , Macintosh AR, Sakwe NI, Vuong NB, Korolkova OY, Sharma V, Misra S, Sakwe AM
Am J Physiol Cell Physiol · 2026 Jun · PMID 42013067 · Full text
Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with poor prognosis and diverse response to treatment that is mostly attributed to heterogeneity of the disease that includes a diverse set of t...
Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with poor prognosis and diverse response to treatment that is mostly attributed to heterogeneity of the disease that includes a diverse set of tumor cells at various stages of the epithelial-to-mesenchymal transition. Despite advances in our understanding of TNBC biology, isolating the phenotypically distinct cell subpopulations and their molecular drivers of invasiveness remains a major challenge. In this study, we used sequential invasion assays in Boyden chambers coated with growth factor-reduced Matrigel to isolate invasive subpopulations from model migratory mesenchymal-like and proliferative epithelial TNBC cell lines. We ascertained phenotypic heterogeneity of the invasive subpopulations by assessing markers of invasiveness, drug response, growth in three-dimensional cultures, and proteomic analysis. We demonstrated that isolated invasive subpopulations of epithelial cells are E-cadherin-low, whereas those from mesenchymal-like TNBC cells are vimentin-high. The isolated invasive subpopulations are chemotherapy-resistant, stem cell-like cells that express distinct druggable drivers of invasiveness, including carbonic anhydrase 9 (CA9, encoded by the gene) in the invasive subpopulations of epithelial TNBC cells. Downregulation of in the invasive subpopulations of epithelial cells resulted in decreased cell proliferation, invasiveness, and sensitivity to chemotherapy. Together, this study demonstrates that targeting specific drivers of invasiveness, such as CA9, in the invasive subpopulations of epithelial cells may provide viable options for novel therapeutic strategies for metastatic TNBC. This study addressed a major challenge in studying phenotypically distinct cell populations within bulk tumors or cell lines by using sequential invasion assays to reliably isolate vimentin-high mesenchymal-like and E-cadherin-low epithelial invasive subpopulations of TNBC cells. The isolated invasive subpopulations from these phenotypically distinct TNBC cell types are chemotherapy-resistant, stem cell-like, and mammosphere-forming tumor cells that express distinct druggable drivers of invasiveness, including in the heterogeneous invasive subpopulations of epithelial TNBC cells.
Mechanistic advances and emerging technologies redefining lung aging research.
Fletcher Wheeler L, Lehmann M, Melo-Narvaez MC
Am J Physiol Cell Physiol · 2026 May · PMID 42003748 · Publisher ↗
As the population ages, defining how biological processes change over the lifetime has become increasingly important. Acute and chronic lung diseases are more prevalent in older adults, and emerging research is beginning...
As the population ages, defining how biological processes change over the lifetime has become increasingly important. Acute and chronic lung diseases are more prevalent in older adults, and emerging research is beginning to uncover the mechanistic and cellular pathways that link aging to conditions such as pneumonia and chronic obstructive pulmonary disease (COPD). Additional mechanisms, particularly those involving extracellular vehicles (EVs), the microbiome, and sex differences, are now recognized as potential contributors to age-related changes in lung health, yet remain underexplored. Advances in experimental models and analytical tools have accelerated progress in the field. Three-dimensional lung models such as organoids, precision-cut lung slices, extracellular matrix (ECM) scaffolds, and lung-on-a-chip systems offer more physiologically relevant systems than traditional two-dimensional cultures, improving translatability to in vivo biology. Meanwhile, the expansion of genomics, transcriptomics, proteomics, and metabolomics has enabled comprehensive, multiomics approaches for mapping disease mechanisms, and such datasets are increasingly available. However, deeper integration with patient metadata and spatially resolved methods is still needed to advance precision medicine approaches to exploit aging mechanisms in chronic lung diseases. In this review, we highlight the importance of investigating EVs, the microbiome, and sex differences and their contribution of age-associated mechanisms in the context of pneumonia and COPD, and discuss how innovations in 3-D lung models and omics technologies are reshaping our understanding of the pathological mechanisms that underlie these diseases.
Hybrid channels containing the dupα7 subunit mediate resistance to α7-nAChR targeting therapy in metastatic melanoma.
Kirichenko AV, Bychkov ML, Kulbatskii DS … +14 more , Shlepova OV, Shulepko MA, Gornostaeva TY, Orekhov PS, Paramonov AS, Mikhaylova IN, Burova OS, Medyanik IA, Yashin KS, Wang H, Wang X, Kirpichnikov MP, Shenkarev ZO, Lyukmanova EN
Am J Physiol Cell Physiol · 2026 May · PMID 41989766 · Publisher ↗
Nicotinic acetylcholine receptor of α7 type (α7-nAChR) is a ligand-gated ion channel composed of five identical α7 subunits. Secreted lymphocyte antigen-6 urokinase-type plasminogen activator receptor (Ly6/uPAR)-related...
Nicotinic acetylcholine receptor of α7 type (α7-nAChR) is a ligand-gated ion channel composed of five identical α7 subunits. Secreted lymphocyte antigen-6 urokinase-type plasminogen activator receptor (Ly6/uPAR)-related protein-1 (SLURP-1) controls carcinoma progression by negative modulation of oncogenic α7-nAChR. In this study, we observed dramatic decrease of SLURP-1 plasma level in patients with metastatic melanoma. We suggested usage of recombinant analog of human SLURP-1 (rSLURP-1) to compensate this deficiency for metastatic melanoma treatment. rSLURP-1 did not affect viability of different patient-derived metastatic melanoma cells, but reduced migration of some of them. Metastatic melanoma cells of other lines were resistant to rSLURP-1. Antimigratory rSLURP-1 effect was mediated by α7-nAChR, whereas resistance to rSLURP-1 correlated with overexpression of human-specific gene, which encodes the α7 subunit with truncated N-terminal region (dupα7) able to form hybrid α7/dupα7-nAChR channels. Electrophysiological study in oocytes showed that rSLURP-1 inhibits α7/dupα7-nAChR weaker than α7-nAChR. In contrast, "Oncotag" peptide, which mimics the loop I of SLURP-1, inhibited α7/dupα7- and α7-nAChRs with similar efficiency. Oncotag suppressed metastatic melanoma cell migration independently on dupα7 expression. Computer modeling provided rationale for altered activities of rSLURP-1 and Oncotag on α7/dupα7-nAChR. The Cancer Genome Atlas Program (TCGA) database analysis revealed correlation between and gene expression and worse survival prognosis for patients with metastatic melanoma. Thus, ) low plasma SLURP-1 level may be a specific marker of metastatic melanoma development, ) metastatic melanoma progression can be controlled by α7-nAChR inhibition, and ) dupα7 overexpression is a new molecular mechanism of melanoma resistance to internal cholinergic control and new target for melanoma treatment. Metastatic melanoma is aggressive skin tumor often resistant to standard therapies. High α7-nAChR expression negatively correlates with survival of patients with metastatic melanoma, who are characterized by SLURP-1 drop in the plasma. Targeting α7-nAChR with recombinant SLURP-1 could significantly suppress metastatic melanoma cell migration; however, overexpression of human-specific dupα7 subunit forming hybrid α7/dupα7-nAChRs causes melanoma resistance to SLURP-1. This resistance can be overcome by the SLURP-1 mimicking peptide Oncotag, which exhibits activity against hybrid α7/dupα7-nAChRs.
NF-κB signaling drives rapid skeletal muscle atrophy in patients with breast cancer: the cost of fighting cancer with chemotherapy.
Mallard J, Debrut L, Hucteau E … +17 more , Somme L, Bischoff H, Moinard-Butot F, Coliat P, Bendjama A, Weltzer L, Sharifi Tafreshi A, Billand C, Charlot A, Boutonnet L, Laverny G, Keime C, Favret F, Schott R, Pivot X, Hureau TJ, Pagano AF
Am J Physiol Cell Physiol · 2026 May · PMID 41989455 · Publisher ↗
Skeletal muscle wasting is a critical clinical challenge in patients with breast cancer treated with chemotherapy, given its correlation with increased mortality risk and decreased therapeutic efficacy. However, the mech...
Skeletal muscle wasting is a critical clinical challenge in patients with breast cancer treated with chemotherapy, given its correlation with increased mortality risk and decreased therapeutic efficacy. However, the mechanisms underlying this side effect remain poorly understood, slowing the development of effective preventive strategies. Here, we conducted a translational study using an innovative multimodal experimental design to comprehensively investigate the mechanisms driving chemotherapy-induced muscle atrophy. We analyzed 72 samples from 36 patients with breast cancer across four experimental groups at various time points during chemotherapy, complemented by in vitro experiments. Through histological, transcriptomic, targeted protein expression, and activity-based analyses, we identified NF-κB signaling and the subsequent upregulation of the ubiquitin-proteasome system as drivers of chemotherapy-induced muscle atrophy. In vitro, sulfasalazine effectively mitigated the imbalance in protein turnover and fully prevented muscle atrophy, offering promising perspectives for clinical translation and improving patient prognosis. By combining acute and chronic muscle biopsies from patients with breast cancer with complementary in vitro experiments, we determined that breast cancer chemotherapy triggers a rapid skeletal muscle atrophy driven by NF-κB activation and subsequent upregulation of the ubiquitin-proteasome system. Importantly, sulfasalazine fully prevented muscle atrophy by mitigating the imbalance in protein turnover, offering promising perspectives for clinical translation and improving patient prognosis.
Advances in cell adhesion, junction dynamics, and their pathophysiological implications.
Wu C
Am J Physiol Cell Physiol · 2026 Jun · PMID 41984071 · Publisher ↗
Abstract loading — click title to view on PubMed.
Cellular and molecular regulation of fibrotic postoperative abdominal adhesions.
Mathewson AJ, Loszko AF, Ackerman JE … +2 more , Wilson NA, Loiselle AE
Am J Physiol Cell Physiol · 2026 May · PMID 41984042 · Full text
Abdominal adhesions are fibrotic bands of tissue that form following damage to the peritoneum, affecting the majority of abdominal surgery patients and resulting in an annual clinical burden exceeding $1.7 billion. Curre...
Abdominal adhesions are fibrotic bands of tissue that form following damage to the peritoneum, affecting the majority of abdominal surgery patients and resulting in an annual clinical burden exceeding $1.7 billion. Currently, adhesiolysis (surgical removal) is the only treatment available for adhesion-related complications but reoperation comes with a high risk of morbidity and increases the likelihood of future adhesion formation, requiring novel therapeutic approaches. Although the mechanisms of adhesion formation are complex, fibroblasts play key roles in both restoration of normal tissue structure-function and pathological adhesion formation. Disruption of homeostatic wound healing pathways, perhaps through aberrant signals from immune cells or the disrupted matrix, causes fibroblasts to produce excess extracellular matrix (ECM), resulting in a tenacious, vascularized, and innervated tissue that poses an intractable risk to patient health. To achieve desirable patient outcomes, therapeutic approaches must target mechanisms that impede adhesiogenesis while facilitating wound healing. However, the identification of these mechanisms is complicated by the diverse origins of adhesion-associated fibroblasts, a poor characterization of adhesion ECM architecture, and a lack of standardized methods to model adhesiogenesis. In this review, we detail the postsurgical loss of peritoneal homeostasis and subsequent cellular response, discussing how the resulting population of adhesion-associated fibroblasts responds to cell-cell and cell-matrix communication, driving adhesion pathogenesis. Given the rapid expansion of fundamental knowledge that has been developed in the last ∼5 yr, this is a critical inflection point for the field that lays the groundwork for the identification of novel antifibrotic abdominal adhesion therapeutics.
Defects in skeletal myotubes caused by STIM1 I115F that lead to tubular aggregate myopathy and Stormorken syndrome, and their restoration at the cellular level.
Jeong SY, Lim H, Hong S … +1 more , Lee EH
Am J Physiol Cell Physiol · 2026 May · PMID 41984033 · Publisher ↗
A genetic mutation in stromal interaction molecule 1 (STIM1) at I115 (I115F) causes tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK), which are multisystemic disorders characterized by miosis, thrombocyto...
A genetic mutation in stromal interaction molecule 1 (STIM1) at I115 (I115F) causes tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK), which are multisystemic disorders characterized by miosis, thrombocytopenia, asplenia, and congenital skeletal muscle weakness. The main cause of this skeletal muscle weakness is excess store-operated Ca entry (SOCE) resulting from the constitutively active I115F STIM1 mutant. This study investigated the detailed mechanisms underlying I115F-induced pathological defects and the possible mechanisms by which these defects can be restored at the cellular level. I115F was overexpressed in mouse primary skeletal myotubes, which were subsequently examined using live single-cell Ca imaging, transmission electron microscopy, and biochemical approaches. In addition, the restoration of I115F-induced pathological defects was examined using I115F-overexpressing myotubes codifferentiated with normal immature myotubes on of differentiation. Constitutively active I115F induced cytosolic Ca overload in I115F-overexpressing myotubes by increasing SOCE and the expression of canonical transient receptor potential cation channel 6 (TRPC6), resulting in an imbalanced Ca distribution between the cytosol and sarcoplasmic reticulum, abnormal mitochondria, low ATP production, and aberrant Ca release for skeletal muscle contraction. Codifferentiation reversed the I115F-induced defects, normalizing cytosolic Ca levels by increasing myogenin expression and myotube width and decreasing ORAI1 expression while maintaining TRPC6 expression. Moreover, codifferentiation reset the intracellular Ca distribution by increasing SERCA1a expression and providing sufficient ATP production. Therefore, this study suggests that I115F-induced cellular Ca dysregulation, which may contribute to skeletal muscle weakness in TAM and STRMK, may be attenuated by modulating myogenin, TRPC6, ORAI1, or SERCA1a expression or activity. Using a mouse myotube model, this study characterizes cellular defects caused by the STIM1 I115F mutation and proposes a hypothetical recovery mechanism via codifferentiation with normal myotubes. Our findings suggest that this restoration could be mediated by modulating myogenin, SERCA1a, ORAI1, and TRPC6 expression, providing mechanistic insights into cellular pathways for restoring skeletal muscle function in patients with TAM and STRMK carrying the STIM1 I115F mutation.
Unacylated ghrelin counteracts mitochondrial dysfunction and neuromuscular junction disruption in cancer cachexia.
Ahn B, Wanagat J, Cleary C … +2 more , Ainsworth HC, Kim H
Am J Physiol Cell Physiol · 2026 May · PMID 41979598 · Full text
Cancer cachexia is a multifactorial metabolic syndrome that profoundly reduces muscle mass, strength, efficacy of chemotherapy, and survival, yet no effective therapy exists. Unacylated ghrelin (UnAG), the predominant fo...
Cancer cachexia is a multifactorial metabolic syndrome that profoundly reduces muscle mass, strength, efficacy of chemotherapy, and survival, yet no effective therapy exists. Unacylated ghrelin (UnAG), the predominant form of circulating ghrelin, promotes muscle growth and mitochondrial bioenergetics, but its role in cancer cachexia remains unknown. Four- to 5-mo-old male C57Bl/6N mice were assigned to three groups: nontumor-bearing (NTB), tumor-bearing (TB), and tumor-bearing treated with UnAG (TB + UnAG). Lewis lung carcinoma cells were inoculated subcutaneously in the flank of the mice. Body weight, food intake, and tumor size were monitored for 4 wk. Lower limb muscle mass, contractile function, mitochondrial respiration, and reactive oxygen species (ROS) production were measured, in conjunction with Western blot, proteomic, and immunohistochemical analyses. Compared with NTB controls, TB mice exhibited marked loss of muscle mass and function, whereas UnAG treatment preserved ∼50% of the muscle mass and ∼70% of the contractile force. UnAG enhanced mitochondrial oxygen consumption, reduced ROS generation, and preserved mitochondrial DNA copy number and downregulated DNA mutation frequency. TB mice demonstrated increased oxidative stress and activation of protein degradation pathways, along with neuromuscular junction disruption-both of which were normalized by UnAG. These findings collectively demonstrate that UnAG mitigates cancer cachexia by modulating mitochondrial bioenergetics, oxidative and proteolytic stress, and neuromuscular junction integrity. UnAG represents a promising therapeutic candidate that may mitigate cachexia and improve both chemotherapy efficacy and the quality of life of patients with cancer. Unacylated ghrelin prevents muscle wasting and maintains neuromuscular junction integrity and contractile function in cancer cachexia. It enhances mitochondrial respiratory capacity through elevated mitochondrial DNA copy number while limiting DNA mutation. It reduces mitochondrial reactive oxygen species (mtROS) generation, oxidative stress, and proteasome-mediated proteolysis-driven muscle degradation.
Overactive PDGFRα and PDGFRβ promote distinct phenotypes of skeletal muscle fibrosis and stiffness, with PDGFRβ also driving muscle growth.
Gimla M, Olszewski S, Brown JL … +8 more , Raymond-Pope CJ, Rigsby S, Peelor FF, Kwon HR, Yao L, Olson LE, Fuqua JD, Miller BF
Am J Physiol Cell Physiol · 2026 May · PMID 41979571 · Full text
Fibrosis accumulates in skeletal muscle over time and leads to greater muscle rigidity, stiffness, and increased risk of injuries. However, investigations of appropriate experimental models to study the mechanisms throug...
Fibrosis accumulates in skeletal muscle over time and leads to greater muscle rigidity, stiffness, and increased risk of injuries. However, investigations of appropriate experimental models to study the mechanisms through which muscle fibrosis occurs are often confounded by injury or disease. The contribution of platelet-derived growth factor receptors alpha and beta (PDGFRα or PDGFRβ) to muscle fibrosis is yet to be clarified. We hypothesized that both receptors would promote extracellular matrix (ECM) deposition and fibrosis, causing muscle stiffening and weakness, with sex-specific differences arising due to hormonal influences on receptors. To test this hypothesis, we used a mouse model with inducible overactive PDGFRα or PDGFRβ signaling and assessed various indicators of muscle function, metabolism, motor coordination, exercise capacity, collagen deposition, and muscle stiffness. Overactive PDGFRα led to higher collagen deposition, collagen cross linking, and AGE/LOX protein levels, all of which correlated with greater muscle stiffness compared with controls. Overactive PDGFRβ resulted in greater muscle mass and lower fat mass and had higher collagen deposition in female mice compared with controls. There were also sex-specific differences with fibrotic remodeling, muscle stiffness, and muscle size in response to overactive PDGFRα and PDGFRβ signaling. These findings establish PDGFRα and PDGFRβ signaling as distinct regulators of muscle remodeling and establish overactive PDGFRα as a mouse model to study skeletal muscle fibrosis in the absence of other confounding variables. This study demonstrates that overactive PDGFRα and PDGFRβ signaling drive distinct and sex-specific skeletal muscle remodeling phenotypes. Overactive PDGFRα induces robust fibrosis characterized by increased insoluble and cross-linked collagen, elevated LOX and AGE levels, and marked muscle stiffness. Thus, establishing a new model to study skeletal muscle fibrosis. Overactive PDGFRβ unexpectedly promoted skeletal muscle hypertrophy and reduced fat mass with minimal fibrosis, revealing a previously unrecognized role in regulating muscle growth in vivo.
Role of Na/H exchanger 3 in acidification and morphological remodeling of tubulovesicles in gastric parietal cells.
Fujii T, Shimizu H, Wiriyasermkul P … +3 more , Nagamori S, Shimizu T, Sakai H
Am J Physiol Cell Physiol · 2026 Jun · PMID 41962948 · Publisher ↗
Gastric parietal cells undergo dramatic morphological changes upon stimulation, during which intracellular tubulovesicles (TV) fuse with the apical canalicular membrane to support massive H secretion by the gastric proto...
Gastric parietal cells undergo dramatic morphological changes upon stimulation, during which intracellular tubulovesicles (TV) fuse with the apical canalicular membrane to support massive H secretion by the gastric proton pump (H,K-ATPase). Although the activation process has been extensively characterized, the mechanisms underlying the return to the resting state remain largely unknown. To elucidate this mechanism, we performed proteomic analysis and Western blotting of tubulovesicles isolated from hog stomach. Interestingly, these analyses revealed high expression of the Na/H exchanger 3 (NHE3) in these tubulovsicles. Immunocytochemical studies further demonstrated colocalization of NHE3 with H,K-ATPase in hog and rat gastric parietal cells. Acridine orange-based measurements of vesicular acidification (H uptake) in hog tubulovesicles showed that the selective NHE3 inhibitors S3226 and tenapanor significantly enhanced H,K-ATPase-mediated acidification. These inhibitors did not affect the ATPase activity of H,K-ATPase in freeze-dried hog tubulovesicles. This excessive acidification was abolished under Na-free conditions. In addition, ATP-dependent Na uptake into hog tubulovesicles, which was inhibited by NHE3 inhibitors, was also suppressed by the H,K-ATPase inhibitor SCH28080. In rat primary cultured parietal cells, apical canalicular structures were visualized using an extracellularly applied fluorescent antibody against H,K-ATPase to monitor morphological recovery from the stimulated state (acid-secreting). This analysis revealed that NHE3 inhibitors prevented the transition from the stimulated to the resting state. These findings suggest that NHE3 is functionally coupled with H,K-ATPase in tubulovesicles and may play a critical role in preventing excessive vesicular acidification and facilitating membrane remodeling during the recovery phase. This study identifies Na/H exchanger 3 (NHE3) as a key regulator of the transition of gastric parietal cells from the acid-secreting state to the resting state. Using purified gastric tubulovesicles and primary cultured rat parietal cells, we demonstrate for the first time that NHE3 prevents excessive tubulovesicular acidification and promotes membrane remodeling. These findings provide new insight into the homeostasis of parietal cells in the regulation of gastric acid secretion.
17β-Estradiol and progesterone have independent and combined effects on C2C12 myotubes following electrical pulse stimulation.
Wageh M, Kamal M, Parise G
Am J Physiol Cell Physiol · 2026 May · PMID 41955091 · Publisher ↗
17β-Estradiol (E2) and progesterone (P4) may influence exercise-induced muscle damage and repair during the menstrual cycle (MC), but their individual and combined effects remain unclear. This study investigated how horm...
17β-Estradiol (E2) and progesterone (P4) may influence exercise-induced muscle damage and repair during the menstrual cycle (MC), but their individual and combined effects remain unclear. This study investigated how hormones influence C2C12 myoblast proliferation, differentiation, and migration under basal conditions and after electrical pulse stimulation (EPS). Myoblasts were treated with E2 and P4 (alone or combined to mimic MC phases). Proliferation (MTT assay), migration (scratch assay), creatine kinase (CK), differentiation (immunohistochemistry), and protein expression (Western blot) were assessed. Elevated E2 (>100 pg/mL) and P4 (>1.5 ng/mL) reduced proliferation, as well as in the early follicular phase (EFP) and mid-luteal phase ( < 0.05). Migration decreased in EFP and late follicular phase (LFP) ( < 0.05), but not with isolated E2/P4 treatment. Differentiation was impaired across all MC phases (reduced myotube diameter; < 0.05). Although greater E2 accelerated CK recovery post-EPS, the presence of P4 (MC phases) influenced this effect. E2 upregulated HSP70 and myogenin protein content, but P4 counteracted these benefits during specific MC phases. ERα increased in all conditions, suggesting a potential role in mediating the EPS response. In conclusion, E2 and P4 independently decrease myoblast activity, but their combined effects vary across the MC, with a potential role of ERα in this process. These findings highlight the complex interplay of sex hormones in the myogenic response to contractile stress. 17β-Estradiol (E2) and progesterone (P4) may differentially regulate myoblast function, with high concentrations suppressing proliferation. Notably, E2 enhances muscle repair after electrical stimulation, but P4 may influence this response when combined with E2 to simulate menstrual cycle phases. The discovery that ERα increases across all hormone treatments suggests a key regulatory role in muscle contractile responses. These findings provide novel insights into how menstrual cycle hormones may influence exercise recovery and muscle adaptation.
Cardiometabolic effects of time-restricted eating.
Søndergaard AM, Kjærulff MLG, Gormsen LC … +1 more , Søndergaard E
Am J Physiol Cell Physiol · 2026 May · PMID 41954637 · Publisher ↗
Time-restricted eating (TRE) confines daily caloric intake to 4-10 h, thereby inducing recurrent fasting intervals of 14-20 h. TRE alters meal timing without the need for calorie counting and has been proposed as a simpl...
Time-restricted eating (TRE) confines daily caloric intake to 4-10 h, thereby inducing recurrent fasting intervals of 14-20 h. TRE alters meal timing without the need for calorie counting and has been proposed as a simple and sustainable dietary intervention with potential metabolic benefits mediated through circadian alignment and increased amount of time spent in the postabsorptive/fasted state. This mini-review summarizes evidence from randomized controlled trials and meta-analyses on cardiometabolic effects of TRE. Studies indicate a modest weight loss compared with ad libitum eating, but with no consistent benefit when compared with caloric restriction. Effects on glycemic control, insulin sensitivity, and lipid profiles are generally small, variable, and context dependent. The most consistent finding is a lowering of blood pressure by about 4/2 mmHg. The effects of TRE on cardiac function and perfusion are still mostly unexplored, but a 3-wk intervention with alternate-day fasting (∼36 h of fasting) improves myocardial flow reserve and reduces oxygen consumption. In summary, TRE appears to be a feasible dietary intervention, but robust evidence of beneficial effects remains limited. Larger and longer-term studies with clinically relevant cardiometabolic endpoints are needed to determine the clinical efficacy of TRE.
Acute effects of ketone monoester ingestion on monocyte phenotype and cytokine secretion in healthy humans.
Marcotte-Chénard A, Sandilands RE, Teixeira AA … +3 more , McCarthy SF, Islam H, Little JP
Am J Physiol Cell Physiol · 2026 May · PMID 41954565 · Publisher ↗
Beta-hydroxybutyrate (BHB) exerts anti-inflammatory effects in cell and animal models, but translational work in humans remains limited. We investigated how exogenous ketone monoester (KME) ingestion in vivo and BHB trea...
Beta-hydroxybutyrate (BHB) exerts anti-inflammatory effects in cell and animal models, but translational work in humans remains limited. We investigated how exogenous ketone monoester (KME) ingestion in vivo and BHB treatment of human whole blood and monocytes ex vivo influence cytokine secretion and phenotype. Healthy adults ( = 13, age = 28 ± 7 yr) consumed a KME supplement containing (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (0.750 g/kg of body mass). Venous blood samples were taken before and 2 h postingestion. Cytokine secretion from lipopolysaccharide (LPS)-stimulated whole blood (4 h) and monocyte (24 h) cultures was used to determine BHB's anti-inflammatory effects, whereas flow cytometry assessed monocyte phenotype and polarization. Blood BHB concentration increased after KME consumption ( < 0.0001), peaking after 2 h (5.0 ± 0.8 mmol/L). Total white blood cells increased 2 h after KME consumption compared with baseline ( = 0.006), mainly due to higher total neutrophils ( = 0.0004). Tumor necrosis factor-alpha (TNF-α) secretion in LPS-stimulated (1 ng/mL) whole blood collected before and 2 h after KME consumption was unaltered ( = 0.616), suggesting that in vivo exposure to increased BHB did not alter blood leukocyte cytokine secretion. However, ex vivo BHB cotreatment of LPS-stimulated whole blood and monocyte cultures decreased TNF-α secretion in a dose-dependent manner ( ≤ 0.0012). BHB cotreatment during 24 h LPS stimulation also decreased monocyte CD80+ ("") expression. Lowering pH of whole blood cultures independent of BHB also reduced TNF-α secretion, albeit to a lesser extent than BHB ( = 0.012). Collectively, BHB lowers proinflammatory monocyte marker expression ex vivo and dose-dependently reduces TNF-α production in LPS-stimulated whole blood and monocyte cultures. These effects appear to be partly mediated by acidification of the extracellular environment. Beta-hydroxybutyrate (BHB) decreased TNF-α production in LPS-stimulated whole blood and monocyte cultures, which appeared partly-although not completely-mediated by the acidification of the cellular environment. The presence of BHB in LPS-stimulated monocyte cultures reduced surface protein expression of CD80, suggesting a shift toward a less proinflammatory monocyte phenotype. Acute elevation of BHB via exogenous ketone supplementation did not appear to alter immune function or monocyte phenotype in healthy humans.
Fluorescence-based quantification of mitochondrial damage in human airway smooth muscle cells.
Mahadev Bhat S, Sieck GC
Am J Physiol Cell Physiol · 2026 May · PMID 41954442 · Full text
Mitochondrial quality control is essential for maintaining cellular homeostasis by balancing the removal of damaged mitochondria (mitophagy) with the generation of new mitochondria (mitochondrial biogenesis). A key featu...
Mitochondrial quality control is essential for maintaining cellular homeostasis by balancing the removal of damaged mitochondria (mitophagy) with the generation of new mitochondria (mitochondrial biogenesis). A key feature of mitochondrial damage is loss of mitochondrial membrane potential (ΔΨ), which initiates mitophagy, enabling effective mitochondrial clearance. Although an array of tools exists to assess mitochondrial damage (depolarization), many rely on acute, nonphysiological depolarization or provide semiquantitative measures of mitochondrial damage, limiting their ability to resolve intact versus damaged mitochondria within heterogeneous mitochondrial networks. Therefore, in the present study, we developed and validated an imaging-based assay to quantify intact mitochondria in human airway smooth muscle (hASM) cells using dual-fluorescence labeling. This approach combines a ΔΨ-dependent (MitoTracker Red FM) dye with a ΔΨ-independent label [CellLight mitochondria-green fluorescent protein (GFP)]. Dual-labeled mitochondria in untreated hASM cells exhibited ∼10% nonoverlap between the two fluorescence signals, indicating the presence of damaged (depolarized) mitochondria in homeostatic conditions. Dose- and time-dependent treatment with the mitochondrial uncoupler carbonyl cyanide--trifluoromethoxyphenylhydrazone (FCCP) induced loss of ΔΨ, confirmed by tetramethylrhodamine methyl ester (TMRM), and resulted in a marked reduction in fluorescence overlap, volume of intact mitochondria, and increased mitochondrial fragmentation. Complementary analysis using the redox-sensitive reporter pMitoTimer was performed, where a shift in fluorescence signal from green to red is indicative of increased mitochondrial oxidative stress and rate of mitochondrial turnover. Together, these findings validate the dual-labeling strategy as a quantitative method to distinguish intact from damaged mitochondria in situ and as a useful tool for studying mitochondrial quality control, potentially translatable to various cell and disease models. We introduce an imaging-based approach to quantitatively distinguish intact from damaged mitochondria within heterogeneous mitochondrial networks using fluorescent labels that exhibit different sensitivities to mitochondrial membrane potential. By combining membrane potential-independent CellLight GFP label with membrane potential-dependent MitoTracker Red, this method sensitively quantifies basal and stress-induced mitochondrial damage in hASM cells. This assay provides a practical and interpretable metric of mitochondrial integrity that complements existing methods that measure mitochondrial membrane potential and oxidative stress.
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