American journal of physiology. Cell physiology最新文献

Primordial germ cells (PGCs) are the earliest progenitors of germline cells of the gonads in animals. The tissues that arise from primordial germ cells give rise to male and female gametes and are thus responsible for transmitting genetic information to subsequent generations. The development of gonads, from single cells to fully formed organs, is of great interest to the reproductive biology community. In most higher animals, PGCs are initially specified at a site away from the gonads. They then migrate across multiple tissue microenvironments to reach a mesodermal mass of cells called the genital ridge, where they associate with somatic cells to form sex-specific reproductive organs. Their migratory behavior has been studied extensively to identify which tissues they interact with and how this might affect gonad development. A crucial point overlooked by classical studies has been the physical environment experienced by PGCs as they migrate and the mechanical challenges they might encounter along the way. It has long been understood that migrating cells can sense and adapt to physical forces around them via a variety of mechanisms, and studies have shown that these mechanical signals can guide stem cell fate. In this review, we summarize the mechanical microenvironment of migrating PGCs in different organisms. We describe how cells can adapt to this environment and how this adaptation can influence cell fate. Finally, we propose that mechanical signals play a crucial role in the normal development of the germline and shed light on this unexplored area of developmental biology.

Ubiquitination is a posttranslational modification that plays important roles in regulating protein stability, function, localization, and protein-protein interactions. Proteins are ubiquitinated via a process involving specific E1 activating enzymes, E2 conjugating enzymes, and E3 ligases. Simultaneously, protein ubiquitination is opposed by deubiquitinating enzymes (DUBs). DUB-mediated deubiquitination can change protein function or fate and recycle ubiquitin to maintain the free ubiquitin pool. Approximately 100 DUBs have been identified in the mammalian genome, and characterized into seven classes [ubiquitin-specific protease (USP), ovarian tumor proteases (OTU), ubiquitin C-terminal hydrolase (UCH), Machado-Josephin disease (MJD), JAB1/MPN/Mov34 metalloprotease (JAMM), Ub-containing novel DUB family (MINDY), and zinc finger containing ubiquitin peptidase (ZUP) classes]. Of these 100 DUBs, there has only been relatively limited investigation of 20 specifically in skeletal muscle cells, in vitro or in vivo, using overexpression, knockdown, and knockout models. To date, evidence indicates roles for individual DUBs in regulating aspects of myogenesis, protein turnover, muscle mass, and muscle metabolism. However, the exact mechanism by which these DUBs act (i.e., the specific targets of these DUBs and the type of ubiquitin chains they target) is still largely unknown, underscoring how little we know about DUBs in skeletal muscle. This review endeavors to comprehensively summarize the current state of knowledge of the function of DUBs in skeletal muscle and highlight the opportunities for gaining a greater understanding through further research into this important area of skeletal muscle and ubiquitin biology.

TGFβ-inhibited membrane associated protein (TIMAP), the endothelial cell-predominant protein phosphatase 1β regulatory subunit also known as PPP1R16B, promotes in vitro endothelial cell proliferation and angiogenic sprouting. TIMAP was first identified as a target of TGF-β1-mediated repression, but the molecular pathways regulating its expression in endothelial cells are not well-defined. This study examined the role of bone morphogenetic factor 9 (BMP9), hypoxia, and angiogenic growth factors in the regulation of TIMAP expression and determined whether TIMAP plays a role in tumor angiogenesis and growth in vivo. BMP9, which potently activated the SMAD1/5/8 pathway in endothelial cells, significantly reduced TIMAP mRNA and protein expression. Conversely, hypoxia and the prolyl hydroxylase inhibitor Roxadustat raised TIMAP mRNA and protein levels by inhibiting the SMAD1/5/8 pathway. Angiogenic growth factors, including VEGFA and IGF-I, raised endothelial TIMAP levels partly by attenuating SMAD1/5/8 pathway activation, but also through SMAD1/5/8-independent mechanisms. Cultured breast cancer E0771 cells released mediators that raised TIMAP expression in endothelial cells, effects that were inhibited by the VEGF inhibitor Sunitinib in conjunction with the IGF-1 inhibitor Picropodophyllin. In the mouse E0771 breast cancer model in vivo, tumor growth and tumor angiogenesis were markedly attenuated in TIMAP deficient, compared with wild-type littermates. These findings indicate that TIMAP plays a critical proangiogenic function during tumor angiogenesis in vivo, likely through hypoxia-driven inhibition of the SMAD1/5/8 pathway and through the elaboration of angiogenic growth factors by tumor cells.NEW & NOTEWORTHY The protein phosphatase 1 regulatory subunit TGFβ-inhibited membrane associated protein (TIMAP), known to activate AKT in endothelial cells (EC), was shown here to be repressed by bone morphogenetic factor 9 (BMP9). Hypoxia and angiogenic growth factors induced TIMAP expression by inhibiting the BMP9 pathway. In a mouse breast cancer model, TIMAP deletion inhibited tumor angiogenesis and tumor growth. Therefore, the proangiogenic functions of TIMAP are induced by hypoxia and angiogenic growth factors.

Neuroplasticity is the brain's ability to reorganize and modify its neuronal connections in response to environmental stimuli, experiences, learning, and disease processes. This encompasses a variety of mechanisms, including changes in synaptic strength and connectivity, the formation of new synapses, alterations in neuronal structure and function, and the generation of new neurons. Proper functioning of synapses, which facilitate neuron-to-neuron communication, is crucial for brain activity. Neuronal synapse homeostasis, which involves regulating and maintaining synaptic strength and function in the central nervous system (CNS), is vital for this process. Disruptions in synaptic balance, due to factors like inflammation, aging, or infection, can lead to impaired brain function. This review highlights the main aspects and mechanisms underlying synaptic homeostasis, particularly in the context of aging, infection, and inflammation.

Perceived stress is thought to contribute to the pathogenesis of metabolic, vascular, mental, and immune diseases, with different susceptibilities in women and men. The present study investigated if and how perceived stress and/or demographic variables, including sex, age, body mass index, regular prescription drugs, occasional analgesics, or dietary supplements, manifested in plasma lipidomic profiles obtained by targeted and untargeted mass spectrometry analyses. The study included 217 healthy women and 108 healthy men, aged 18-68 yr, who were recruited in a 2:1 female:male ratio to account for women with/without contraceptives. As expected, dehydroepiandrosterone sulfate (DHEAS) and ceramides were higher in men than women, and DHEAS decreased with age, whereas ceramides increased. Contrary to expectations, neither DHEAS nor ceramides were associated with perceived stress [Perceived Stress Questionnaire with 30 questions (PSQ30 questionnaire)], which was, however, associated with BMI in men but not in women. None of the lipid species or classes showed a similar "age × sex × BMI" interaction, but the endocannabinoid palmitoylethanolamide (PEA) correlated with body mass index (BMI) and hypertension. Independent of perceived stress, lysophosphatidylcholines (LPCs) were lower in women than men, whereas LPC metabolites, lysophosphatidic acids (LPAs), were higher in women. The LPA:LPC ratio was particularly high in women using oral contraceptives, suggesting a strong hormone-induced extracellular conversion of LPCs to LPAs, which is catalyzed by the phospholipase D, autotaxin. The results reveal complex sex differences in perceived stress and lipidomic profiles, the latter being exacerbated by contraceptive use, but perceived stress and lipids were not directly correlated.NEW & NOTEWORTHY Perceived stress (PSQ questionnaire) depends on the interaction of "sex × age × BMI." Plasma lipid profiles depend on sex and age. Natural sex differences are exacerbated by the use of contraceptives. Perceived stress is not correlated with specific plasma lipids or lipidomic profiles. Women have high LPA:LPC ratios in association with high levels of autotaxin.

The voltage-gated potassium channel Kv1.3 plays a crucial role in the immune system response. In leukocytes, the channel is co-expressed with the dominant negative regulatory subunit KCNE4, which associates with Kv1.3 to trigger intracellular retention and accelerate C-type inactivation of the channel. Previous research has demonstrated that the main association between these proteins occurs through both COOH-termini. However, these data fail to fully elucidate the KCNE4-dependent modulation of channel kinetics. In the present study, we analyzed the contribution of each KCNE4 domain to the modulation of Kv1.3. Our results further confirmed that the COOH-terminus of KCNE4 is the main determinant involved in the association-triggered intracellular retention of the channel. In addition, interactions throughout the transmembrane region were also observed. Both the COOH-terminus and, especially, the transmembrane domain of KCNE4 accentuated the C-type inactivation of Kv1.3. Our data provide, for the first time, the molecular effects that a KCNE peptide, such as KCNE4, exerts on a Shaker channel, such as Kv1.3. Our results pave the way for understanding the molecular mechanisms underlying potassium channel modulation and suggest that KCNE4 participates in the conformational rearrangement of the Kv1.3 architecture, altering the C-type inactivation of the channel.NEW & NOTEWORTHY This work defines, for the first time, the interactions between a Kv1 (Shaker) channel and a KCNE regulatory subunit. While the COOH-terminus of KCNE4 physically interacts with the channel, its transmembrane domain shapes the inactivation properties of the functional complex, fine-tuning the Kv1.3-dependent physiological response in leukocytes.

Diabetic encephalopathy (DE), a neurological complication of diabetes mellitus, has an unclear etiology. Shreds of evidence show that the nucleotide-binding oligomerization domain-like receptor family protein 3 (NLRP3) inflammasome-induced neuroinflammation and transcription factor EB (TFEB)-mediated autophagy impairment may take part in DE development. The cross talk between these two pathways and their contribution to DE remains to be explored. A mouse model of type 2 diabetes mellitus (T2DM) exhibiting cognitive dysfunction was created, along with high-glucose (HG) cultured BV2 cells. Following, 3-methyladenine (3-MA) and rapamycin were used to modulate autophagy. To evaluate the potential therapeutic benefits of TFEB in DE, we overexpressed and knocked down TFEB in both mice and cells. Autophagy impairment and NLRP3 inflammasome activation were noticed in T2DM mice and HG-cultured BV2 cells. The inflammatory response caused by NLRP3 inflammasome activation was decreased by rapamycin-induced autophagy enhancement, while 3-MA treatment further deteriorated it. Nuclear translocation and expression of TFEB were hampered in HG-cultured BV2 cells and T2DM mice. Exogenous TFEB overexpression boosted NLRP3 degradation via autophagy, which in turn alleviated microglial activation as well as ameliorated cognitive deficits and neuronal damage. In addition, TFEB knockdown exacerbated neuroinflammation by decreasing autophagy-mediated NLRP3 degradation. Our findings have unraveled the pathogenesis of a previously underappreciated disease, implying that the activation of NLRP3 inflammasome and impairment of autophagy in microglia are significant etiological factors in the DE. The TFEB-mediated autophagy pathway can reduce neuroinflammation by enhancing NLRP3 degradation. This could potentially serve as a viable and innovative treatment approach for DE.NEW & NOTEWORTHY This article delves into the intricate connections between inflammation, autophagy, diabetes, and neurodegeneration, with a particular focus on a disease that is not yet fully understood-diabetic encephalopathy (DE). TFEB emerges as a pivotal regulator in balancing autophagy and inflammation in DE. Our findings highlight the crucial function of the TFEB-mediated autophagy pathway in mitigating inflammatory damage in DE, suggesting a new treatment strategy.

Pulmonary hypertension (PH) is a progressive vascular disease characterized by vascular remodeling, stiffening, and luminal obstruction, driven by dysregulated cell proliferation, inflammation, and extracellular matrix (ECM) alterations. Despite the recognized contribution of ECM dysregulation to PH pathogenesis, the precise molecular alterations in the matrisome remain poorly understood. In this study, we employed a matrisome-focused proteomics approach to map the protein composition in a young bovine calf model of acute hypoxia-induced PH. Our findings reveal distinct alterations in the matrisome along the pulmonary vascular axis, with the most prominent changes observed in the main pulmonary artery. Key alterations included a strong immune response and wound repair signature, characterized by increased levels of complement components, coagulation cascade proteins, and provisional matrix markers. In addition, we observed upregulation of ECM-modifying enzymes, growth factors, and core ECM proteins implicated in vascular stiffening, such as collagens, periostin, tenascin-C, and fibrin(ogen). Notably, these alterations correlated with increased mean pulmonary arterial pressure and vascular remodeling. In the plasma, we identified increased levels of complement components, indicating a systemic inflammatory response accompanying the vascular remodeling. Our findings shed light on the dynamic matrisome remodeling in early-stage PH, implicating a wound-healing trajectory with distinct patterns from the main pulmonary artery to the distal vasculature. This study provides novel insights into the immune cell infiltration and matrisome alterations associated with PH pathogenesis and highlights potential biomarkers and therapeutic targets within the matrisome landscape.NEW & NOTEWORTHY Extensive immune cell infiltration and matrisome alterations associated with hypoxia-induced pulmonary hypertension in a large mammal model. Matrisome components correlate with increased resistance to identify candidate alterations that drive biomechanical manifestations of the disease.

During the reproductive life, most primordial follicles remain dormant for years or decades, while some are progressively activated for development. Misactivation of primordial follicles can cause ovarian diseases, for example, premature ovarian insufficiency (POI). Our results show that p300 expression increased with primordial follicle activation. Using a p300 inhibitor resulted in premature activation of primordial follicles in cultured mouse ovaries. Conversely, the ratio of primordial follicle activation was markedly decreased upon culturing with the p300 agonist. Furthermore, p300 regulated primordial follicle activation by inhibiting Vegfa transcription in granulosa cells. Additionally, this study was extended to potential clinical applications, showing that short-term treatment with a p300 inhibitor in vitro significantly increased primordial follicle activation in newborn mouse ovaries after dorsal kidney membrane transplantation in female NSG mice. Our results revealed that p300 controls the activation of primordial follicles in mammalian ovaries.

Several studies have demonstrated that diabetes mellitus can increase the risk of cardiovascular disease and remains the principal cause of death in these patients. Costameres connect the sarcolemma with the cytoskeleton and extracellular matrix, facilitating the transmission of mechanical forces and cell signaling. They are related to cardiac physiology because individual cardiac cells are connected by intercalated discs that synchronize muscle contraction. Diabetes impacts the nanomechanical properties of cardiomyocytes, resulting in increased cellular and left ventricular stiffness, as evidenced in clinical studies of these patients. The question of whether costameric proteins are affected by diabetes in the heart has not been studied. This work analyzes whether type 1 diabetes mellitus (T1DM) modifies the costameric proteins and coincidentally changes the cellular mechanics in the same cardiomyocytes. The samples were analyzed by immunotechniques using laser confocal microscopy. Significant statistical differences were found in the spatial arrangement of the costameric proteins. However, these differences are not due to their expression. Atomic force microscopy was used to compare intrinsic cellular stiffness between diabetic and normal cardiomyocytes and obtain the first elasticity map sections of diabetic living cardiomyocytes. Data obtained demonstrated that diabetic cardiomyocytes had higher stiffness than control. The present work shows experimental evidence that intracellular changes related to cell-cell and cell-extracellular matrix communication occur, which could be related to cardiac pathogenic mechanisms. These changes could contribute to alterations in the mechanical and electrical properties of cardiomyocytes and, consequently, to diabetic cardiomyopathy.NEW & NOTEWORTHY The structural organization of cardiomyocyte proteins is critical for their efficient functioning as a contractile unit in the heart. This work shows that diabetes mellitus induces significant changes in the spatial organization of costamere proteins, t tubules, and intercalated discs. We obtained the first elasticity map sections of living diabetic cardiomyocytes. The results show statistical differences in the map sections of diabetic and control cardiomyocytes, with diabetic cardiomyocytes being stiffer than normal ones.