Cellular and Molecular Life Sciences最新文献

Drug-induced mitochondrial toxicity is a major contributing factor to cardiotoxicity, which can cause drug attrition and adverse cardiac events. To assess the toxicity of anti-inflammatory agents, we used adult human primary cardiomyocytes (hPCMs) to screen 18 clinically available anti-inflammatory drugs in a high-content manner, and revealed widespread mitochondrial dysfunction without affecting cell viability. Nabumetone, a representative nonsteroidal anti-inflammatory drug with profound mitochondrial toxicity, induced mitochondrial fission, inhibited mitophagy, and impaired both electrophysiological and metabolic functions in adult hPCMs. Mechanistically, we uncovered that nabumetone (Nab) exerted its toxic effects through the prostaglandin E2- E-type prostanoid receptor 4 (PGE₂-EP₄) pathway, which was essential for its anti-inflammatory functions. To find an alternative route to ameliorate mitochondrial damage, we identified SIRT3 as a downstream target of nabumetone. Its mRNA, protein, and activity levels were significantly reduced upon nabumetone treatment. SIRT3 activator honokiol exhibited protective potential against NSAID-induced mitochondrial toxicity both in hPCMs and in nabumetone-treated mice. Finally, through screening mitochondrial liability in various common cardiomyocyte models, we identified mitochondrial abundance as an important determinant of the sensitivity of cells towards mitochondrial toxicants. Our study demonstrates the vast presence of mitochondrial dysfunction in human adult cardiomyocytes imposed by clinically used anti-inflammatory drugs, and identified both toxicity and protective pathways that may serve future therapeutic purposes.

Trophoblast and amniotic lineages, representing key extra-embryonic tissues, can be differentiated from human pluripotent stem cells (hPSCs) under chemically defined conditions. However, the regulatory mechanisms coordinating the fate decision between these lineages during PSC differentiation remain incompletely understood. Leveraging CRISPR/Cas9-mediated loss-of-function screening in lineage-reporter PSCs, we identified the transcription factor HAND1 as a critical determinant controlling the bifurcation of trophoblast and amniotic lineages. Genetic ablation of HAND1 effectively abrogated the amniotic differentiation capacity of PSCs while concomitantly enhancing their trophoblast differentiation potential. Conversely, ectopic HAND1 overexpression impaired trophoblast differentiation. Notably, forced HAND1 expression in human trophoblast stem cells (TSCs) induced transcriptional reprogramming toward an amniotic fate, indicating its lineage-instructive capability. Mechanistic analyses demonstrated that HAND1 interacts with the TCFs and Wnt signaling effectors β-catenin to form a transcriptional complex that antagonistically modulates the balance between trophoblast- and amnion-associated gene regulatory networks. Collectively, our findings establish HAND1 as a master regulator orchestrating the amniotic versus trophoblast lineage choice during human PSC differentiation, thereby illuminating fundamental regulatory mechanism underlying extra-embryonic lineage specification.

Macrophage polarization plays a vital role in regulating inflammation, and the balance of this process is crucial for maintaining tissue health and influencing disease progression. Recent studies have shown how macrophages can adapt their phenotypes in response to their surroundings, underscoring the importance of their polarization changes in various inflammatory conditions, such as infections, tumors, metabolic disorders, and autoimmune diseases. This review brings together significant advancements in our understanding of the signaling pathways involved in inflammation, the role of epigenetic factors, metabolic changes, and the development of targeted therapies, with the goal of offering new perspectives on treating inflammation-related diseases.

Background: Age-related hearing loss (ARHL), also known as presbycusis, is a prevalent condition among older adults and affects a substantial proportion of the global aging population. The underlying mechanisms of ARHL remain unclear, and this study aimed to explore the role of superenhancers (SEs) and the transcription factor Sp1 in regulating hair cell (HC) aging and ferroptosis, a form of regulated cell death associated with iron metabolism.

Methods: We utilized a combination of bioinformatics analysis, including transcriptional regulatory element enrichment analysis (TREA) and SE prediction, with SEdb 2.0 to identify key transcriptional regulators and their target genes. Experimental validation was performed using auditory brainstem response (ABR) measurements, immunofluorescence staining, Western blot analysis and quantitative real-time PCR (RT‒qPCR) in mouse and cell models. Additionally, we employed CUT&Tag assays to map Sp1 binding sites and performed statistical analyses using SPSS Statistics 25 and GraphPad Prism.

Results: Our study revealed that reduced binding of Sp1 to the Fth1 superenhancer triggered HC ferroptosis and the progression of ARHL. We identified Sp1 as a key upstream transcriptional regulator whose binding to the Fth1 SE decreased with aging, leading to reduced Fth1 gene transcription and increased intracellular iron levels. This phenomenon resulted in cellular iron overload, subsequent ferroptosis, and increased reactive oxygen species (ROS) levels, ultimately promoting HC and cochlear aging. In vivo studies with the SE inhibitor JQ-1 confirmed the importance of SE activity in maintaining auditory function.

Conclusions: This study provides evidence for the role of Sp1 and Fth1 in the regulation of HC aging and ARHL. These findings suggest that manipulating SE sites and inhibiting ferroptosis may offer novel therapeutic strategies for treating ARHL. Understanding the interplay between SEs, Sp1, Fth1 and ferroptosis reveals novel targets for AAV gene therapy to preserve hearing in aging populations by modulating iron homeostasis during sensory cell senescence.

Mitochondrial metabolism is fundamental to cardiac and skeletal muscle function due to the high adenosine triphosphate (ATP) demand required for sustained contractility. Although mitochondrial dysfunction is central to metabolic myopathies, the epigenetic mechanisms regulating mitochondrial structure and function remain poorly defined. Here, we identify the SWI/SNF chromatin remodeling ATPase subunit Smarca4 as a critical regulator of mitochondrial homeostasis and cellular energy metabolism. Using a smarca4a-deficient zebrafish model (smarca4a^a8-/-), we show that Smarca4 loss causes ventricular hypoplasia, pericardial edema, and disorganized skeletal muscle, leading to pronounced impairment of cardiac and muscular function. Heart-specific RNA-seq, ATAC-seq, and single-cell RNA-seq analyses revealed that Smarca4 deficiency reduces chromatin accessibility and suppresses the transcription of genes controlling mitochondrial biogenesis and oxidative phosphorylation. Consistently, high-resolution confocal imaging and Seahorse-based metabolic profiling demonstrated marked reductions in mitochondrial content, respiratory capacity, and ATP generation. AAV-mediated SMARCA4 knockdown in human cardiomyocytes and murine myotubes reproduced these mitochondrial defects. Collectively, these findings establish Smarca4 as a conserved chromatin remodeling factor linking nuclear regulation to mitochondrial energy homeostasis during vertebrate muscle development.

The conformational activation of α_IIbβ₃integrin is crucial for platelet aggregation, a central event in hemostasis and thrombosis. Although activation can be triggered by extracellular arginine-glycine-aspartic acid (RGD)-containing ligands as well as mechanical forces, how these biochemical and mechanical cues exactly govern the structural dynamics of α_IIbβ₃remains unclear. Here, using all-atom molecular dynamics simulations, we show that mechanical force and RGD binding promote activation α_IIbβ₃through distinct mechanisms. Mechanical force applied to the RGD-binding site induces long-range, correlated motions of distant parts of the receptor, facilitating head-leg separation. In contrast, RGD binding increases localized, non-correlated fluctuations that weaken leg coordination but do not generate long-range motions. Despite these differences, both cues stabilize the open, extended conformation of α_IIbβ₃. Together, these findings suggest that mechanical and biochemical stimuli play complementary yet distinct roles in integrin conformational activation. A balance between global coordination and local fluctuations likely governs integrin activation in complex environments where the dominance of mechanical or biochemical cues could lead to distinct activation pathways and functional outcomes.