American journal of physiology. Cell physiology最新文献

Calcium signaling via store-operated calcium entry (SOCE) is critical for cellular functions implicated in cancer progression. Alterations in Orai channel isoforms, particularly Orai1 and Orai3, modulate SOCE and influence tumor cell proliferation, invasion, and survival. Here, we review and synthesize current evidence showing how Orai1 and Orai3 isoforms modulate oncogenic calcium signals through pathways such as phosphatidylinositol 3-kinase (PI3K)/Akt, ERK1/2, and NF-κB, contributing to tumor progression and chemoresistance by regulating apoptosis, autophagy, and oxidative stress responses. This isoform-specific remodeling enables tumor cells to adapt to therapeutic challenges and oxidative environments. Emerging data suggest that modulating Orai channel function and isoform composition may sensitize some cancer cells to apoptosis and attenuate invasive behavior, at least in specific experimental models. Taken together, available studies support a role for Orai channels as important regulators of tumor-associated Ca²⁺ signaling and highlight their potential as context-dependent targets to modulate survival and invasive behavior in cancer models.

Cystamine, the oxidized dimer of cysteamine, has been reported to exert anti-inflammatory actions, but the underlying molecular mechanism remains unclear. Because the histamine H₄ receptor (H4R) is a key regulator of mast cell chemotaxis and inflammatory signaling, we examined whether cystamine directly modulates H4R activity. Cystamine potently inhibited histamine-induced mast cell migration (IC₅₀ = 440 nM) without affecting stem cell factor-induced migration, indicating pathway specificity. Although cystamine suppressed transglutaminase activity, this required millimolar concentrations and did not account for its effect on migration. At low micromolar concentrations, cystamine attenuated histamine-dependent activation of Rac1 and Rac2 GTPases and extracellular signal-regulated kinase (ERK). In H4R-expressing HEK293A cells, cystamine reduced basal and agonist-induced cyclic AMP response element reporter activity, demonstrating competitive antagonism and inverse agonism. Molecular docking supported direct binding of cystamine-but not its reduced monomer, cysteamine-to H4R. These findings identify cystamine as a redox-dependent inverse agonist of the H4R and provide a mechanistic explanation for its reported anti-inflammatory properties. Notably, cystamine generated endogenously or reformed locally from cysteamine under oxidative conditions may act on H4R in a redox-dependent and microenvironment-specific manner. Together, these insights suggest the potential for developing redox-dependent, tissue-selective H4R modulators for inflammatory diseases.NEW & NOTEWORTHY This study identifies cystamine as a previously unrecognized modulator of H4R. Cystamine inhibits mast cell migration and suppresses H4R-mediated Rac-ERK signaling at concentrations far below those required to inhibit transglutaminase, and it exhibits inverse agonist activity. Docking simulations show that cystamine, but not reduced cysteamine, engages the receptor's orthosteric site, revealing a redox-dependent difference in receptor interaction.

Endotrophin, a biologically active fragment derived from the α3 chain of collagen type VI, has emerged as both a risk biomarker and a potential pathogenic factor in cardiovascular-kidney-metabolic (CKM) syndrome. Over the past decade, research has shed light on its role in various noncommunicable diseases, emphasizing its signaling properties and diagnostic potential. Despite these advances, significant gaps remain in our understanding of how endotrophin contributes to CKM pathophysiology and whether targeting it therapeutically could modify disease progression. This narrative review synthesizes current evidence on endotrophin biological functions and clinical associations, drawing from both experimental and clinical studies. In addition, it identifies critical areas where further investigation is required, including the molecular mechanisms linking endotrophin to CKM-related tissue dysfunction and its causal role in disease development. By mapping current knowledge and highlighting research priorities, this review aims to advance the field toward a more complete understanding of endotrophin as a potential therapeutic target.

The hepatobiliary system is constantly exposed to dynamic mechanical forces, including fluid shear stress, bile canaliculi pressure, and extracellular matrix stiffness. Although traditionally studied for its metabolic and detoxifying functions, it is now increasingly recognized as a mechanosensitive organ. This review focuses on PIEZO1 mechanically gated ion channels that transduce physical cues into calcium-dependent signaling events. PIEZO2, the only other PIEZO isoform, is not known to be relevant in the hepatobiliary system. We examine the current knowledge on PIEZO1 in liver physiology, highlighting its roles in liver sinusoidal endothelial cells, hepatocytes, and macrophages. In health, PIEZO1 regulates key processes such as bile acid synthesis (through nitric oxide-mediated suppression of CYP7A1), bile flow, antioxidant defense, and iron homeostasis. In disease, PIEZO1 activity is linked to pathological processes such as inflammation, fibrosis, and angiogenesis in the context of cirrhosis and hepatocellular carcinoma. We discuss the idea that the liver alternates between two functional states depending on portal vein flow: a high-flow state favoring detoxification and metabolism, and a low-flow state that prioritizes bile acid production. Understanding how PIEZO1 contributes to these transitions offers new insights into liver's ability to adapt its function and metabolism. Further research on hepatobiliary PIEZO1 will advance the understanding of how physical exercise promotes health and opens new opportunities for enhancing liver regeneration after surgical resection and liver function in chronic diseases such as fibrosis and cirrhosis.

M₁ and M₃ muscarinic receptors encoded by CHRM1 and CHRM3 mediate neuronal and non-neuronal cholinergic signaling. Mice with global M₃R deficiency reportedly weigh less than controls, but the cell type(s) involved are unknown. As the intestinal epithelium modulates nutrient absorption, we asked whether deleting M₁R and M₃R only from intestinal epithelial cells would alter the distribution of specialized small intestinal epithelial cells or body weight. We reviewed reports of global M₁R and M₃R deficiency and body weight, used single-cell RNA sequencing (scRNA-Seq) to assess Chrm1 and Chrm3 expression by small intestinal epithelial cells, created mice with conditional intestinal epithelial cell M₁R and M₃R deletion (CKO mice), and compared the distribution of specialized intestinal epithelial cells and body weights of CKO and control mice, and the development of enteroids. Prior weight comparisons commonly used only male mice, frequently without comparison with littermate controls. scRNA-Seq analysis of tissues from M₁R and M₃R floxed mice revealed robust Chrm1 and Chrm3 expression by enteric goblet cells. CKO mice with selective mucosal depletion of Chrm1 and Chrm3 RNA were viable, fertile, and had fewer small intestinal goblet cells than controls. M₃R CKO mice had more tuft cells than controls. Although female mice weighed ∼20% less than males, we detected no weight differences between M₁R and M₃R CKO and control mice; enteroids derived from these mice developed at the same pace. Intestinal epithelial cell M₁R and M₃R deficiency impacts the distribution of specialized intestinal epithelial cells but not murine body weight.NEW & NOTEWORTHY Small intestinal goblet cells robustly express both Chrm1 and Chrm3; mucosal immune cells express primarily Chrm3. Mice with intestinal epithelial cell (IEC) Chrm3/M₃R deletion have fewer small intestinal goblet cells but more tuft cells. The increase in tuft cells, which produce acetylcholine, may represent a feedback mechanism to compensate for reduced muscarinic receptor (MR) expression. IEC-selective deletion of MRs does not impact murine weight or enteroid development, suggesting that MRs beyond the intestinal epithelium regulate weight.

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) are promising for the treatment of liver diseases, including acute liver failure (ALF). However, efficient preservation methods suitable for clinical use remain under investigation. In this study, we evaluated the preservation efficacy and therapeutic effects of lyophilized MSC-EVs in a mouse model of ALF. EVs were isolated from bone marrow-derived MSCs and allocated to four preservation conditions: nonlyophilized (fresh), phosphate-buffered saline (PBS), 1% sucrose, and 5% sucrose. EVs were characterized by nanoparticle tracking analysis, Bioanalyzer, absorbance measurements, RNA sequencing, and transmission electron microscopy (TEM). ALF was induced by d-galactosamine and TNF-α, and mice were treated with PBS, empty EVs (m-Encapsome), nonlyophilized EVs, or lyophilized EVs (5% sucrose). Among the preservation conditions, the 5% sucrose group retained the highest EV yield, exhibited a unimodal particle size distribution, and preserved EV morphology, whereas the PBS and 1% sucrose groups showed structural damage and multimodal particle size distributions. Total RNA and protein levels were comparable among groups; however, miRNA sequencing demonstrated a strong correlation between nonlyophilized EVs and 5% sucrose-lyophilized EVs. In the ALF model, 5% sucrose-lyophilized EVs significantly reduced serum alanine transaminase (ALT) levels, inflammatory cytokines, hepatocyte necrosis, TUNEL-positive cells, PCNA-positive cells, and Ki-67-positive cells, with effects comparable to those of nonlyophilized EVs. These findings demonstrate that lyophilization with 5% sucrose effectively preserves MSC-EV integrity and therapeutic potential, supporting future clinical applications of MSC-EVs for liver disease treatment.NEW & NOTEWORTHY This study establishes lyophilization with 5% sucrose as an effective preservation method for mesenchymal stem cell-derived extracellular vesicles (MSC-EVs). Preserved EVs maintained structural integrity and miRNA profiles comparable to fresh EVs. In a mouse model of acute liver failure, they demonstrated equivalent therapeutic efficacy. These findings overcome storage limitations, facilitating the clinical translation of MSC-EVs as a stable treatment for liver diseases.

Precise oxygen regulation is essential for maintaining neuronal integrity in ex vivo brain slice electrophysiology, yet conventional chambers provide poorly defined oxygenation. This limitation is particularly problematic when model neurological disorders are characterized by transient or intermittent hypoxia (IH), such as transient ischemic attacks and sleep apnea. We aimed to develop a versatile oxyslice recording chamber (ORC), enabling real-time monitoring of neural activity with rapid, precise oxygen modulation during standard recordings. A polydimethylsiloxane (PDMS)-based ORC comprising a gas-permeable membrane that separates the recording and gas chambers was developed, allowing rapid and uniform oxygen exchange. The device integrates seamlessly into standard electrophysiological setups and operates at low perfusion rates. Tissue oxygenation was measured, and hippocampal slices were exposed to continuous hypoxia (CH, 3% or 1% O₂) and IH (6-1% O₂ cycles every 30 s) while recording field excitatory postsynaptic potentials (fEPSPs) in the hippocampal CA1 region. The ORC achieved precise, reproducible control of oxygen at the cellular level. Both CH and IH induced hypoxia severity-dependent reductions in fEPSP slopes, fully reversed upon reoxygenation. Severe CH (1% O₂) reduced the fEPSP slope by ∼60%, whereas IH reduced it by ∼40%, indicating a partial mitigation during reoxygenation phases. This novel ORC provides a robust, adaptable method for real-time oxygen modulation in ex vivo neuronal standard recordings. Its ability to model continuous and intermittent hypoxia at physiological oxygen tensions fills a major gap in current electrophysiological methodologies, opening new opportunities for mechanistic studies of hypoxia-driven dysfunction and therapeutic discovery.NEW & NOTEWORTHY This study presents the oxyslice recording chamber (ORC), a simple and reproducible system for precise oxygen control during brain slice recordings. The ORC has been developed to be easily constructed and implemented in any electrophysiology laboratory. As a proof of concept, we reproduced continuous hypoxia (transient ischemic stroke) and intermittent hypoxia (sleep apnea), revealing distinct and reversible changes in hippocampal function applicable to various hypoxia-related conditions and brain regions.

Estrogen is a steroid hormone involved in the regulation of multiple systems in the body. Among these, the immune system is of particular interest due to the significant female predominance seen in many autoimmune diseases. Since B cells and B-cell-driven antibody responses are central to the development of autoimmune diseases, the influence of estrogen on B cells has been extensively investigated. Throughout B-cell development, estrogen exerts complex and contrasting effects depending on the level of exposure to estrogen and the stage of development of the B cell. For instance, at early stages, high concentrations of estrogen negatively regulate early B-cell precursor development, whereas low baseline concentrations are stimulatory and essential. Conversely, estrogen exposure at later stages leads to increased rescue of autoreactive B cells, enabling their maturation and subsequent autoantibody production, a mechanism that contributes to the development of a systemic lupus erythematosus-like phenotype in murine models. Beyond rescuing autoreactive cells, estrogen can also modulate the function of germinal centers, where autoreactive antibodies may arise through somatic hypermutation. The complex interplay of these effects sets the stage for both the heightened immune response and increased autoimmunity observed in females. In this review, we will explore the various effects of estrogen on B cells to provide a comprehensive overview of the role of estrogen in shaping immune function and enhancing autoimmunity.

Liver fibrosis is a progressive disease primarily driven by the activation of hepatic stellate cells (HSCs). Understanding the mechanisms regulating HSC activation requires an in vitro model that accurately recapitulates the hepatic microenvironment. In vivo, quiescent HSCs form direct contact with hepatocytes (Heps) through fine dendritic processes known as spines, which are essential for maintaining liver architecture and homeostasis. However, conventional extracellular matrix-based culture systems fail to reproduce these physiological cell-cell interactions. In this study, we aimed to establish a novel HSC culture platform using Heps plasma membrane (Hep-PM) as a substrate to mimic direct Heps-HSCs adhesion. Primary mouse and human HSCs cultured on Hep-PM retained dendritic, star-like morphologies characteristic of quiescent cells and exhibited markedly reduced expression of alpha-smooth muscle actin (α-SMA) and collagen type I alpha 1, key markers of HSC activation. Remarkably, Hep-PM also promoted the deactivation of activated HSCs, suggesting that both activation and reversion processes can be recapitulated in vitro. Furthermore, HSCs maintained on Hep-PM remained responsive to transforming growth factor β (TGF-β), indicating that quiescence was preserved without loss of activation potential. This system recreates the hepatic microenvironment, enabling dynamic and quantitative evaluation of HSC phenotypes. The Hep-PM platform offers a powerful tool for elucidating HSC regulatory mechanisms and screening antifibrotic compounds and may ultimately inform the design of Heps-mimetic therapeutics for liver fibrosis.NEW & NOTEWORTHY We developed a hepatocyte plasma membrane-based culture system that mimics in vivo cell-cell adhesion to regulate hepatic stellate cell (HSC) phenotypes. This platform maintains HSC quiescence by reducing activation markers and preserving a quiescent morphology, while allowing the observation of HSC activation in response to TGF-β treatment. It provides a physiologically relevant tool for studying HSC regulation and screening antifibrotic therapies, advancing in vitro modeling of liver fibrosis.