International Journal of Biological Sciences最新文献

Pulmonary hypertension (PH) is driven by pulmonary vascular remodeling, in which the zinc-sensing transcription factor metal-responsive transcription factor 1 (MTF-1) may play a pivotal regulatory role. Rodent models of hypoxia-induced PH and cultured pulmonary arterial smooth muscle cells (PASMCs) were used to investigate zinc-mediated MTF-1 activation. Phos-tag SDS-PAGE, site-directed mutagenesis, Cleavage Under Targets and Tagmentation (CUT&Tag), and pharmacological inhibitors were employed to dissect the PKCδ/MTF-1/placental growth factor (PlGF) pathway. CUT&Tag profiling revealed prominent MTF-1 enrichment at promoter regions under hypoxia, with significant occupancy at the Plgf locus and enrichment of angiogenesis-related genes. Hypoxia increased intracellular zinc levels, activated PKCδ, and triggered phosphorylation of MTF-1 at Ser³⁰⁴. This modification was essential for MTF-1 nuclear translocation and PlGF transcription. Mutation of Ser³⁰⁴ or MTF-1 knockdown suppressed PASMCs proliferation and migration under hypoxia and zinc exposure. Gö 6983 abrogated MTF-1 phosphorylation and downstream responses, and selective knockdown of PKCδ reproduced these effects, confirming PKCδ as the predominant isoform mediating MTF-1 activation. In vivo, MTF-1 and PlGF were upregulated in pulmonary vessels of Su/Hx-PH rats, while APTO-253 treatment attenuated pulmonary vascular remodeling and improved cardiopulmonary hemodynamics in hypoxic mice. This study identified PKCδ-dependent phosphorylation of MTF-1 at Ser³⁰⁴ as a critical mechanism linking zinc accumulation to PlGF-driven PASMCs proliferation. Targeting the zinc/PKCδ/MTF-1/PlGF axis represented a novel therapeutic strategy for hypoxic PH.

Acute kidney injury (AKI) is a severe clinical syndrome strongly associated with mitochondrial dysfunction and oxidative stress, yet effective therapies remain elusive. Here, we identify cell division cycle 42 (CDC42) as a critical mediator of AKI. Analysis of human single-cell RNA sequencing (scRNA-seq) dataset revealed marked upregulation of CDC42 in renal tubular epithelial cells (RTECs), which was validated in murine models of cisplatin- and ischemia-reperfusion-induced AKI. Pharmacological inhibition, conditional knockdown, or genetic ablation of CDC42 significantly alleviated renal injury, preserved mitochondrial function, and reduced reactive oxygen species (ROS) both in vivo and in vitro. Mechanistically, transcriptomic analysis, bioinformatic analysis, dual-luciferase reporter assays, ChIP assays and cellular functional validation revealed that CDC42 suppression activated a KLF2/HIF-1α/PINK1 transcriptional cascade, thereby promoting mitophagy and restoring mitochondrial homeostasis. Functional assays supported that this pathway plays a pivotal role in protecting RTECs from oxidative damage. Collectively, these findings uncover a previously unrecognized role of CDC42 in AKI pathogenesis and highlight CDC42 inhibition as a promising therapeutic strategy for mitigating mitochondrial damage and improving renal outcomes.

Amplification and high expression of the c-Myc gene promote the proliferation and metastasis of cancer, contributing to treatment resistance and poor prognosis. In this study, we analyzed whole genome sequencing data from 663 pairs of esophageal squamous cell carcinoma (ESCC) tumors and matched adjacent noncancerous esophagus tissues. The analysis revealed that c-Myc had an amplification rate of 16.4%, and its high expression was significantly associated with tumor metastasis, chemotherapy resistance, and poor prognosis of the patients. Drugs that can inhibit the oncogenic function of c-Myc currently have limited effects. Therefore, we screened for inhibitors that can sensitize c-Myc inhibitors. We found that SGC2085, a CARM1 inhibitor, enhanced the efficacy of MYCi975, a c-Myc inhibitor. This combination disrupts the transcriptional c-Myc-p300-CARM1 (CPC) complex by R371 with R372 in c-Myc and E75 with Y153 in CARM1. Additionally, the combination promotes the accumulation of arachidonic acid, which in turn induces ferroptosis. Furthermore, the combination of SGC2085 and MYCi975 significantly increased B cells, CD8⁺T cells infiltration and decreased the level of CD8⁺ T cell exhaustion, neutrophils, and MDSC. These findings revealed that SGC2085 and MYCi975 could disrupt the transcriptional complex CPC, affect metabolic pathways, and reprogram the immune microenvironment. This study provides a potential therapeutic strategy for ESCC patients.

Metabolic dysfunction-associated steatohepatitis (MASH)-associated fibrosis involves inflammation accompanied by reactive oxygen species (ROS), in addition to abnormal lipid metabolism and extracellular matrix (ECM) deposition. ROS levels are regulated by the NRF2-KEAP1 pathway. Transmembrane 4 L six family member 5 (TM4SF5) is implicated in metabolic dysfunction-associated steatotic liver disease (MASLD). However, it remains unknown how hepatocyte TM4SF5 modulates abnormal lipid and ROS accumulations during MASLD development. Here we assessed the influence of TM4SF5 on NRF2-KEAP1 pathway utilizing various in vitro and in vivo MASLD models. Our results indicate that hepatocyte TM4SF5 downregulates KEAP1 in physiological states and stabilizes KEAP1 in pathological conditions, without altering NRF2 expression. However, TM4SF5-dependent stabilization of KEAP1 was not observed in Tm4sf5 ^-/- KO mice. At least the cytosolic TM4SF5 C-terminus could bind to KEAP1 for proteosomal degradation. TM4SF5-driven biphasic KEAP1 regulation was associated with increased CD36 levels in normal livers, whereas in hyperlipidemic states, it contributed to oxidative stress and hepatic inflammation. Genetically engineered mice with altered Tm4sf5 and Nrf2 displayed TM4SF5-induced MASLD phenotypes characterized by elevated Keap1, regardless of Nrf2 expression or activity. These findings were more obvious than for mice with Nrf2 mutation alone. Notably, suppression of Keap1 alone nullified the MASLD-promoting effects of TM4SF5. Taken together, these data demonstrate that TM4SF5 can modulate KEAP1 independently of NRF2, identifying TM4SF5-mediated KEAP1 stabilization as a potential therapeutic target for MASLD.

Vaccination triggers the release of pro-inflammatory cytokines, the stimulation of the Janus Kinase (JAK) - Signal Transducer and Activator of Transcription (STAT) pathway and the activation of interferon response genes. While some JAK/STAT variants are associated with hematopoietic malignancies, the impact of the vast majority is unknown. Here we identify JAK/STAT germline variants in a Tyrolian cohort, including octogenarians, and link specific rare variants to enhanced vaccine-induced interferon transcriptomic responses. AlphaFold 3 predicted conformational changes in JAK and STATs variants, impacting their interactions and formation of receptor complexes. We also identified co-occurring variants in TYK2 and other modulators of interferon signaling that possibly modify the impact of JAK and STAT variants in the innate immune response. Our results demonstrate that the vaccine-induced innate immune transcriptomic response can be used for an in vivo functional assessment of mutations controlling key genetic pathways in the innate immune response.

Kidney fibrosis is the most common pathology and endpoint of CKD. Unraveling the mechanisms of kidney fibrosis is crucial. Activating transcription factors (ATFs) are implicated in a range of kidney diseases, but their roles in kidney fibrosis remain underexplored. In our investigation, employing an unbiased screening of ATF expression in fibrotic kidneys via analyzing single-cell and bulk RNA sequencing, we identified that ATF3 as the key player, markedly upregulated in damaged tubular epithelial cells (TECs). Crucially, ATF3 deletion in mice markedly attenuated kidney fibrosis and abrogated fibrotic traits in injured TECs. At the molecular level, ATF3 was found to recruit HDAC6 to the SMAD7 promoter, eradicating histone 3 lysine 14 acetylation (H3K14ac) and diminishing SMAD7 transcription. This interaction between ATF3 and HDAC6 culminated in the suppression of Smad7, triggering the TGF-β/Smad3 pathway and exacerbating kidney fibrosis. Collectively, our findings shed light on the complex underpinnings of kidney fibrosis and herald novel therapeutic targets for combating CKD.

The regulation of the homeostasis of the glutamate (Glu)-glutamine (Gln) cycle within the medial prefrontal cortex (mPFC) has garnered substantial interest due to its essential role in maintaining normal emotional behaviors. Chronic stress possesses the potential to disrupt the homeostasis of the Glu-Gln cycle, thereby facilitating the onset of depressive behaviors. Nevertheless, the specific roles of individual components within the Glu-Gln cycle in relation to depression-related behaviors remain incompletely understood. This study aims to elucidate the specific roles of each component by implementing a cell- and region-specific conditional knockout (cKO) strategy. To achieve this goal, the genes encoding glutamine synthetase (GS), glutamate transporter 1 (GLT-1), and sodium-coupled neutral amino acid transporters, SNAT-3 and SNAT-5, were selectively ablated within astrocytes. In addition, the genes encoding SNAT-1 and SNAT-2 were specifically eliminated from glutamatergic neurons. A depressive phenotype was observed in the GS and GLT-1 cKO mice, correlated with increased levels of reactive oxygen/nitrogen species (ROS/RNS) within the mPFC, whereas a reduction in Glu-Gln concentrations was uniquely identified in the GS cKO mice. Conversely, mice with cKO for SNAT-1, SNAT-2, SNAT-3, or SNAT-5 neither exhibited observable depressive-like behaviors nor reduced Glu-Gln levels. However, the simultaneous inactivation of either SNAT-1/SNAT-2 or SNAT-3/SNAT-5 induced depressive-like behaviors and reduced Glu-Gln levels. No systemic stress response or inflammatory manifestations were detected in any of the cKO mice. Furthermore, administration of Gln, acknowledged for its antidepressant properties, to GS cKO mice led to the amelioration of both depressive-like behaviors and Glu-Gln concentrations. These findings elucidate distinct and synergistic roles for the components involved in the Glu-Gln cycle in upholding appropriate Glu-Gln levels and mitigating ROS/RNS within the mPFC. Additionally, our cKO mouse models prove to be valuable tools in researching depression, which may aid in the development of new antidepressant treatments.

Following spinal cord injury (SCI), the transcriptional regulator yes-associated protein 1 (YAP1) is upregulated and accumulates in the nuclei of astrocytes, where it promotes reactive astrogliosis-a process that critically influences wound healing and neurological function recovery. However, the mechanisms regulating YAP1 in reactive astrocytes after SCI remain largely unclear. This study, we identify the E3 ubiquitin ligase NEDD4 as a critical regulator of astrocyte reactive proliferation. NEDD4 enhances astrogliosis by suppressing YAP1 degradation. Conditional deletion of Nedd4 in astrocytes markedly attenuates reactive astrogliosis in vivo, and results in heightened inflammation, exacerbated neuronal injury, and impaired functional recovery following SCI. Importantly, YAP1 overexpression is sufficient to reverse the pathological and functional consequences of Nedd4 deficiency. Mechanistically, NEDD4 interacts with YAP1 and mediates K63-linked ubiquitination at lysine 254, thereby preventing its degradation via the chaperone-mediated autophagy (CMA) pathway involving HSC70. Furthermore, we demonstrate that the ROS-FOXM1 signaling cascade drives NEDD4 expression, thereby stabilizing YAP1 and promoting astrocyte proliferation. In summary, our findings underscore the pivotal role of the ROS-FOXM1-NEDD4-YAP1 signaling cascade in controlling astrocytic activation and tissue regeneration post-SCI, positioning NEDD4 as a viable target to regulate astrogliosis and facilitate neurological restoration after SCI.

Disruption of mitochondria-associated endoplasmic reticulum membranes (MAMs) and calcium homeostasis has been implicated in the pathogenesis of Parkinson's disease (PD). Parkin, a PD-associated E3 ubiquitin ligase, has been shown to regulate MAM integrity and calcium dynamics. However, the mechanisms of Parkin recruitment and its substrate specificity have not been well understood. This investigation has demonstrated that loss of Parkin enhances ER-mitochondria associations and leads to excessive calcium flux in MAM, resulting in abnormal mitochondrial permeability transition pore (mPTP) opening and decreased cell viability. Further, Parkin physically interacts with IP3R-Grp75-VDAC1 complex at ER-mitochondria contact sites, where it is recruited by IP3R-mediated calcium flux and mitophagy. More importantly, Parkin deficiency leads to the accumulation of IP3R levels, particularly in MAM region. In addition, Parkin fine-tunes the stability of the complex and ubiquitinates IP3R for degradation via the ubiquitin-proteasomal system, ensuring suitable calcium transfer. Taken together, our study reveals a novel role of Parkin in regulating ER-mitochondria contacts, providing insights into PD pathogenesis and potential therapeutic strategies targeting MAMs.

Cell death within the tumor microenvironment (TME) plays a pivotal role in shaping tumor-specific immunity. The dynamic interplay between cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) is central to tumor progression and immune regulation. Here, we show that conditioned medium (CM) from lung CAFs exposed to apoptotic cancer cells selectively impairs the survival of M2-like macrophages, induces apoptosis, and promotes their reprogramming toward an M1-like phenotype. These effects were abrogated by knockdown of Wnt-induced signaling protein 1 (WISP-1) in CAFs, identifying WISP-1 as a key paracrine effector. Mechanistically, WISP-1 signals through the integrin α5β3-STAT1 axis to mediate M2 TAM apoptosis and M1-like reprogramming. In vivo, intratumoral injection of CM derived from CAF exposed to apoptotic 344SQ cells reduced overall TAM density, decreased the proportion of M2-like TAMs, and promoted their reprogramming toward an M1-like phenotype, accompanied by STAT1 activation in M2 TAMs. This phenotypic shift was associated with increased infiltration of cytotoxic CD8⁺ T cells and reduced accumulation of regulatory T cells within the tumor. Notably, these effects were abolished by either depletion of WISP-1 from the CM or pharmacological inhibition of STAT1 following recombinant WISP-1 administration. Collectively, our findings identify the WISP-1-integrin α5β3-STAT1 axis as a novel therapeutic target for TAM reprogramming and tumor suppression in lung cancer.