American journal of physiology. Cell physiology最新文献

Macrophages are critical cellular mediators within the innate immune system and are the central effectors of chronic inflammation at the cellular level. Here, macrophages regulate the ongoing, simultaneous processes of tissue inflammation, destruction, and repair. They also play an integral role in recruiting key cell types within the inflammatory and wound healing response. Cancer is a chronic inflammatory state and largely considered a wound that does not heal. As in wound healing, where macrophages engulf and/or destroy foreign insults, macrophages have the potential to also eliminate tumor cells. However, it is now well known that these early pro-inflammatory, anti-tumor responses by macrophages are nullified as macrophages repolarize into pro-tumor, anti-inflammatory tumor-associated macrophages (TAMs) in response to tumor cell and microenvironmental-derived factors. After this point, TAMs drive neoplastic progression in multiple distinct ways. This indirect control of tumor progression, where TAMs share great functional overlap with the direct control elicited by neoplastic cells, supports TAMs being central orchestrators and later conductors of the tumor microenvironment (TME) - the focus of our review.

Retinoid signaling is increased in the hearts of patients with coronary artery disease and during acute myocardial infarction (MI). The effects of retinoids on cardiac repair after injury remain incompletely understood. Our laboratory has derived proliferative cardiac cell clones from adult human left ventricle biopsies and is investigating how these cells might participate in cardiac repair in heart failure. We treated clones isolated from unique individuals with retinoic acid (RA) and performed unbiased proteomics, bioinformatic analyses, and targeted follow-up experiments to identify and confirm RA-regulated factors and processes. RA increased the expression of well-known proinflammatory proteins including interleukin-1 (IL1A and B) and inducible cyclooxygenase 2 (COX2), while decreasing the expression of extracellular matrix (ECM) factors such as thrombospondin 1 and collagens. Additionally, we found that basal expression of retinoid metabolizing enzymes (e.g., ALDH1A3) significantly correlated with expression of cytokines and inflammatory mediators including IL1A/B and COX2 across clones from different donors. Secretion of IL1B by clones was found to respond to physiological and pharmacological doses of RA, and monocyte migration in vitro responded to secretions from RA-treated clones. Our findings suggest a mechanism by which retinoids promote inflammation and contribute to adverse cardiac remodeling in the injured heart, providing a potential avenue to regulate myocardial inflammation and remodeling processes.NEW & NOTEWORTHY Within the injured heart, cells are exposed to elevated retinoic acid signaling resulting from mobilized stores of its precursor, vitamin A, and increased cardiac expression of synthesizing enzymes. This study investigated the effects of retinoic acid, a potent regulator of cell fate and function, on human proliferative cardiac cell clones derived from left ventricle biopsies. The results show an increase in inflammatory factor secretion, immune cell activation, and decreased extracellular matrix expression.

Extracellular vesicles (EVs) are key mediators of intercellular communication and regulators of cellular function, yet their roles in metabolic health and exercise response are poorly understood. This pilot study analyzed plasma from older adults (n = 20) in subgroups of the well-characterized Studies Targeting Risk Reduction Interventions through Defined Exercise (STRRIDE) study to evaluate plasma EV biomarkers as minimally invasive biomarkers of metabolic health and exercise responsiveness. Plasma EVs comprised highly heterogeneous subpopulations defined by diverse surface markers reflecting complex cellular origins. At baseline, multiple EV biomarkers related to immune cells, skeletal muscle, and mesenchymal stem cells were associated with better indices of insulin action, including nine EV subpopulations with lower fasting insulin concentration and eight with lower Homeostatic Model Assessment for Insulin Resistance. Low-amount (∼1,300 kcal/wk), vigorous-intensity (65%-80% peak oxygen consumption) aerobic exercise increased the FABP4⁺ EV subpopulation in older adults (n = 12). High-amount (∼2,200 kcal/wk), vigorous-intensity exercise increased 15 EV subpopulations in older adults (n = 8). These subpopulations arise from a variety of cell sources, including immune cells (primarily lymphoid cells), skeletal and cardiac muscle, erythroid cells, mesenchymal and hematopoietic stem cells. Notably, eight out of 15 high-amount exercise-induced EV subpopulations were insulin action-related (CD29⁺, CD8⁺, CD56⁺, CD19⁺, MCAD⁺, CD73⁺, CD105⁺, and CD235a⁺). The EV-based profiling platform established here is ready for validation in larger human exercise cohorts, including the full STRRIDE cohort.NEW & NOTEWORTHY Specific plasma EV biomarkers related to immune subsets, skeletal muscle, and mesenchymal stem cells were associated with better indices of insulin action at baseline. High-volume, vigorous-intensity aerobic exercise increased many of these insulin action-related EV subpopulations. We developed a novel, minimally invasive platform that uses plasma EV surface markers to assess metabolic health and exercise responsiveness. This platform is ready for validation in larger human cohorts, including the full STRRIDE cohort.

Lysosomal dysfunction and elevated lysosomal pH are hallmark features of age-related neurodegenerative diseases including age-related macular degeneration (AMD), Alzheimer's disease (AD), and Parkinson's disease (PD). Restoring lysosomal acidity is important for maintaining enzymatic degradation, preventing protein aggregation, and reducing cellular waste accumulation in degenerating tissues. Acidic nanoparticles represent a promising therapeutic strategy to normalize lysosomal pH; however, accurate monitoring of their delivery, retention, and dosage is critical for rigorous evaluation. To address this, we developed fluorescently labeled poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles conjugated with Cyanine3 amine (Cy3). Nanoparticle uptake was systematically optimized, achieving over 90% delivery to lysosomes of induced pluripotent stem cell-derived retinal pigment epithelial (iPS-RPE) cells, although uptake rates varied among adjacent cells. Once internalized, nanoparticles demonstrated remarkable stability, with no detectable change in concentration, distribution, or size for at least 28 days. iPS-RPE cells exhibited higher nanoparticle internalization compared with the ARPE-19 cell line and optic nerve head astrocytes. The capacity of the nanoparticles to restore function to stressed lysosomes was confirmed by their ability to reacidify lysosomes, restore cathepsin B activity, and increase the levels of active cathepsin D. The nanoparticles also reduced the levels of LC3II in astrocytes treated with chloroquine, indicating that they can also restore autophagy rates. In summary, this study demonstrates the value of Cy3 labeling for enhanced nanoparticle tracking to lysosomes. The findings also identify PLGA nanoparticles as powerful tools for restoring degradative lysosomal function and autophagy in cells undergoing lysosomal stress.NEW & NOTEWORTHY Tools that restore acidic pH in compromised lysosomes can enhance autophagy and waste clearance in degenerative disorders characterized by excessive accumulation. Here, we describe the synthesis of lysosome-targeted nanoparticles composed of poly(d,l-lactide-co-glycolide) (PLGA) polymers covalently bound to the fluorescent dye Cyanine3 amine (Cy3). These Cy3-PLGA nanoparticles enable precise tracking of lysosomal delivery and demonstrate sustained long-term retention within lysosomes, supporting their potential for future applications aimed at restoring lysosomal pH in aging and degenerating diseases.

G protein-coupled receptor 39 (GPR39) is an orphan receptor that is highly expressed in renal collecting duct principal cells. GPR39 activation in vivo leads to reduced urinary concentration capacity. In this study, we used mpkCCD cells, a model of principal cells in the collecting duct, to examine the cell biological effects of GPR39 activation. Pharmacological activation of GPR39 with the synthetic agonist cpd1324 impaired vasopressin-mediated aquaporin-2 (AQP2) apical trafficking and reduced total AQP2 expression following long-term treatment, consistent with its known in vivo role. These effects were absent in GPR39 knockout cells. In addition, GPR39 activation altered apical membrane morphology, disrupted the tight junction network, and reduced cortical F-actin expression, suggesting a shift toward a dedifferentiated phenotype. GPR39 activation also increased glycolytic ATP production while reducing mitochondrial ATP output without affecting proliferation. RNA-Seq analysis of acutely treated mpkCCD cells revealed upregulation of inflammatory and dedifferentiation-associated gene programs, including cytokines. These findings indicate that the role of GPR39 in principal cells goes beyond AQP2 regulation and imply that GPR39 functions as a negative regulator of epithelial differentiation, perhaps acting to coordinate metabolic and inflammatory responses to stress.NEW & NOTEWORTHY This study presents the first exploration of the cellular and molecular mechanisms underlying GPR39 activation in a physiologically relevant in vitro model of the renal collecting duct, mpkCCD cells. Our findings implicate GPR39 in the regulation of aquaporin-2 expression and trafficking, cytoskeletal organization, and cellular metabolism. In addition, RNA sequencing of GPR39-activated cells revealed transcriptomic changes related to immune signaling, stress response, and differentiation.

Tenascin C (TNC), an extracellular matrix glycoprotein, is crucial for embryonic development and tissue repair, inflammation, extracellular matrix remodeling, and fibrosis, particularly in kidney diseases. Although its expression is typically low in healthy adult kidneys, TNC is upregulated in various kidney disease conditions, including acute kidney injury (AKI) and chronic kidney disease (CKD). TNC influences fibroblast activation, and elevated TNC levels correlate with CKD severity, highlighting its potential as a biomarker for diagnosis and monitoring of fibrogenesis. TNC's multifaceted role offers opportunities for therapeutic interventions. Here, we provide an overview of TNC's structural and functional attributes, its regulatory mechanisms, and its multifactorial role in kidney disease development and progression. We also discuss recent approaches aiming to use TNC as a target for diagnostic and therapeutic purposes.

Reactive astrogliosis, a hallmark of central nervous system pathologies, involves a spectrum of astrocyte responses, including morphological remodeling and the upregulation of intermediate filaments such as vimentin and glial fibrillary acidic protein (GFAP). Changes in astrocyte shape are driven by cytoskeletal dynamics and are important for interactions with the surrounding microenvironment. Focal adhesions (FAs), which serve as physical and signaling links between the cytoskeleton and the extracellular matrix, play a central role in these structural adaptations. Here, we identify plectin, a versatile cytoskeletal linker, as an important modulator of FA-associated processes in cultured mouse astrocytes. We demonstrate that plectin localizes to FAs in astrocytes, and its deficiency is associated with changes in their number, maturation, and turnover. Plectin also displays polarization within FAs, depending on their maturation state, and it contributes to the recruitment of key cytoskeletal elements, particularly vimentin, to FAs. In plectin-deficient astrocytes, the vimentin and GFAP network exhibits impaired connectivity, accompanied by altered viscoelastic properties of the cells. Compared with astrocytes maintained in serum-free neurobasal medium, astrocytes cultured in serum-containing medium, which resemble reactive astrocytes, exhibit elevated plectin levels along with an increased number and size of FAs, supporting the involvement of plectin in pathological conditions.NEW & NOTEWORTHY Plectin contributes to FA dynamics in astrocytes and exhibits spatial polarization within individual FAs as revealed by superresolution microscopy (SIM and STED). Atomic force microscopy demonstrated that plectin deficiency alters cell viscoelasticity, unveiling the role of plectin in the mechanical properties of astrocytes. Plectin expression, along with the FA protein vinculin, is upregulated in astrocytes cultured under serum-containing conditions-an in vitro model of reactive astrocytes-compared with serum-free, native-like conditions.

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.