Cellular and Molecular Life Sciences最新文献

Fibronectin (FN) is an extracellular matrix glycoprotein essential for the development and function of major vertebrate organ systems. Mutations in FN result in an autosomal dominant skeletal dysplasia termed corner fracture-type spondylometaphyseal dysplasia (SMDCF). The precise pathomechanisms through which mutant FN induces impaired skeletal development remain elusive. Here, we have generated patient-derived induced pluripotent stem cells as a cell culture model for SMDCF to investigate the consequences of FN mutations on mesenchymal stem cells (MSCs) and their differentiation into cartilage-producing chondrocytes. In line with our previous data, FN mutations disrupted protein secretion from MSCs, causing a notable increase in intracellular FN and a significant decrease in extracellular FN levels. Analyses of plasma samples from SMDCF patients also showed reduced FN in circulation. FN and endoplasmic reticulum (ER) protein folding chaperones (BIP, HSP47) accumulated in MSCs within ribosome-covered cytosolic vesicles that emerged from the ER. Massive amounts of these vesicles were not cleared from the cytosol, and a smaller subset showed the presence of lysosomal markers. The accumulation of intracellular FN and ER proteins elevated cellular stress markers and altered mitochondrial structure. Bulk RNA sequencing revealed a specific transcriptomic dysregulation of the patient-derived cells relative to controls. Analysis of MSC differentiation into chondrocytes showed impaired mesenchymal condensation, reduced chondrogenic markers, and compromised cell proliferation in mutant cells. Moreover, FN mutant cells exhibited significantly lower transforming growth factor beta-1 (TGFβ1) expression, crucial for mesenchymal condensation. Exogenous FN or TGFβ1 supplementation effectively improved the MSC condensation and promoted chondrogenesis in FN mutant cells. These findings demonstrate the cellular consequences of FN mutations in SMDCF and explain the molecular pathways involved in the associated altered chondrogenesis.

Background: Our previous study found that tumor suppressor nitrogen permease regulator like-2(NPRL2) is frequently downregulated in glioma, leading to malignant growth. However, NPRL2-mediated crosstalk between tumor cells and immune cells remains unclear.

Methods: The regulatory effects of NPRL2 on tripartite motif-containing protein 16(TRIM16) dependent ubiquitination degradation of Galectin-3(Gal-3) were explored. The effects of Gal-3 on copper uptake, immunocompetence and cuproptosis were investigated in CD8⁺T lymphocytes(CD8⁺T cells). The ability of NPRL2 to protect CD8⁺T cells from Gal-3 damage was evaluated. Furthermore, the correlations among NPRL2, TRIM16, Gal-3 and CD8⁺T cell accumulation were analyzed in glioma clinical specimens.

Results: NPRL2 increased the TRIM16 expression via inactivation of ERK1/2, which in turn promoted the ubiquitination-mediated degradation of Gal-3 and diminished Gal-3 release from glioma cells. Moreover, Gal-3 accelerated copper uptake and triggered cuproptosis in CD8⁺T cells, whereas NPRL2 increased CD8⁺T cell recruitment and prevented impairment of CD8⁺T cells by Gal-3. Clinical samples revealed that NPRL2 expression was positively associated with TRIM16 expression and negatively correlated with Gal-3, but Gal-3 expression was negatively associated with CD8⁺T cell accumulation.

Conclusion: Glioma-derived NPRL2/TRIM16/Gal-3 axis participates in the regulation of CD8⁺T cell cuproptosis, which provides a promising strategy to rescue the immune activity of CD8⁺T cells and reverse immunosuppression in glioma.

Active vitamin D, known for its role in promoting osteoporosis, has immunomodulatory effects according to the latest evidence. Eldecalcitol (ED-71) is a representative of the third-generation novel active vitamin D analogs, and its specific immunological mechanisms in ameliorating diabetic osteoporosis remain unclear. We herein evaluated the therapeutic effects of ED-71 in the context of type 2 diabetes mellitus (T2DM), delving into its underlying mechanisms. In a T2DM mouse model, ED-71 attenuated bone loss and marrow adiposity. Simultaneously, it rectified imbalanced glucose homeostasis and dyslipidemia, ameliorated pancreatic β-cell damage and hepatic glycolipid metabolism disorder. Subsequently, in mice injected with the Treg cell-depleting agent CD25, we observed that the beneficial effects of ED-71 mentioned earlier were partially contingent on the Treg subsets ratio. Mechanistically, ED-71 promoted the differentiation of CD4⁺ T cells into Treg subsets, facilitating Ca²⁺ influx and the expression of ORAI1 and STIM1, pivotal proteins in store-operated Ca²⁺ entry (SOCE). The SOCE inhibitor, 2-APB, partially attenuated the positive effects of ED-71 observed in the above results. Overall, ED-71 regulates SOCE-mediated Treg cell differentiation, accomplishing the dual purpose of simultaneously ameliorating diabetic osteoporosis and glucolipid metabolic disorders, showcasing its potential in osteoimmunity therapy and interventions for diseases involving SOCE.

Zinc (Zn) transporters contribute to the maintenance of intracellular Zn homeostasis in vertebrate, whose activity and function are modulated by post-translational modification. However, the function of small ubiquitin-like modifier (SUMOylation) in Zn metabolism remains elusive. Here, compared with low Zn group, a high-Zn diet significantly increases hepatic Zn content and upregulates the expression of metal-response element-binding transcription factor-1 (MTF-1), Zn transporter 6 (ZnT6) and deSUMOylation enzymes (SENP1, SENP2, and SENP6), but inhibits the expression of SUMO proteins and the E1, E2, and E3 enzymes. Mechanistically, Zn triggers the activation of the MTF-1/SENP1 pathway, resulting in the reduction of ZnT6 SUMOylation at Lys 409 by small ubiquitin-like modifier 1 (SUMO1), and promoting the deSUMOylation process mediated by SENP1. SUMOylation modification of ZnT6 has no influence on its localization but reduces its protein stability. Importantly, deSUMOylation of ZnT6 is crucial for controlling Zn export from the cytosols into the Golgi apparatus. In conclusion, for the first time, we elucidate a novel mechanism by which SUMO1-catalyzed SUMOylation and SENP1-mediated deSUMOylation of ZnT6 orchestrate the regulation of Zn metabolism within the Golgi apparatus.

The leading cause of steroid-induced femoral head osteonecrosis (ONFH) is the imbalance of bone homeostasis. Bone marrow-derived mesenchymal stem cell (BMSC) differentiation and fate are closely associated with bone homeostasis imbalance. Blocking monoacylglycerol lipase (MAGL) could effectively ameliorate ONFH by mitigating oxidative stress and apoptosis in BMSCs induced by glucocorticoids (GC). Nevertheless, whether MAGL inhibition can modulate the balance during BMSC differentiation, and therefore improve ONFH, remains elusive. Our study indicates that MAGL inhibition can effectively rescue the enhanced BMSC adipogenic differentiation caused by GC and promote their differentiation toward osteogenic lineages. Cannabinoid receptor 2 (CB2) is the direct downstream target of MAGL in BMSCs, rather than cannabinoid receptor 1(CB1). Using RNA sequencing analyses and a series of in vitro experiments, we confirm that the MAGL blockade-induced enhancement of BMSC osteogenic differentiation is primarily mediated by the phosphoinositide 3-kinases (PI3K)/ the serine/threonine kinase (AKT)/ (glycogen synthase kinase-3 beta) GSK3β pathway. Additionally, MAGL blockade can also reduce GC-induced bone resorption by directly suppressing osteoclastogenesis and indirectly reducing the expression of receptor activator of nuclear factor kappa-Β ligand (RANKL) in BMSCs. Thus, our study proposes that the therapeutic effect of MAGL blockade on ONFH is partly mediated by restoring the balance of bone homeostasis and MAGL may be an effective therapeutic target for ONFH.

The existence of cancer stem cells (CSCs) in pancreatic ductal adenocarcinoma (PDAC) is considered to be the key factor for metastasis and chemoresistance. Thus, novel therapeutic strategies for eradicating CSCs are urgently needed. Here we aimed to explore the role of KLF15 in stemness and the feasibility of using KLF15 to inhibit CSCs and improve chemotherapy sensitivity in PDAC. In this study, we report that KLF15 is negatively associated with poor survival and advanced pathological staging of PDAC. Moreover, tumorous KLF15 suppresses the stemness of PDAC by promoting the degradation of Nanog, and KLF15 directly interacts with Nanog, inhibiting interaction between Nanog with USP21. We also demonstrate that the KLF15/Nanog complex inhibit the stemness in vivo and in PDX cells. Tazemetostat suppresses stemness and sensitizes PDAC cells to gemcitabine by promoting KLF15 expression in PDAC. In summary, the findings of our study confirm the value of KLF15 level in diagnosis and prognosis of PDAC, it is the first time to explore the inhibition role of KLF15 in stemness of PDAC and the regulation mechanism of Nanog, contributing to provide a new therapeutic strategy that using Tazemetostat sensitizes PDAC cells to gemcitabine by promoting KLF15 expression for PDAC.

Mounting evidence has implicated the RNA m⁶A methylation catalyzed by METTL3 in a wide range of physiological and pathological processes, including tumorigenesis. The detailed m⁶A landscape and molecular mechanism of METTL3 in prostate cancer (PCa) remains ill-defined. We find that METTL3 is overexpressed in PCa and correlates with worse patient survival. Functional studies establish METTL3 as an oncoprotein dependent on its m⁶A enzymatic activity in both AR⁺ and AR^- PCa cells. To dissect the regulatory network of m⁶A pathway in PCa, we map the m⁶A landscape in clinical tumor samples using m⁶A-seq and identify genome-wide METTL3-binding transcripts via RIP-seq. Mechanistically, we discover RRBP1 as a direct METTL3 target in which METTL3 stabilizes RRBP1 mRNA in an m⁶A-dependent manner. RRBP1 positively correlates with METTL3 expression in PCa cohorts and exerts an oncogenic role in aggressive PCa cells. Leveraging the 3D structural protein-protein interaction between METTL3 and METTL14, we successfully develop two potential METTL3 peptide inhibitors (RM3 and RSM3) that effectively suppress cancer cell proliferation in vitro and tumor growth in vivo. Collectively, our study reveals a novel METTL3/m⁶A/RRBP1 axis in enhancing aggressive traits of PCa, which can be therapeutically targeted by small-peptide METTL3 antagonists.

The intricate connection between the gut and the brain involves multiple routes. Several viral families begin their infection cycle in the intestinal tract. However, amongst the long list of viral intestinal pathogens, picornaviruses, and astroviruses stand out for their ability to transition from the intestinal epithelia to central or peripheral nervous system cells. In immunocompromised, neonates and young children, these viral infections can manifest as severe diseases, such as encephalitis, meningitis, and acute flaccid paralysis. What confers this remarkable plasticity and makes them efficient in infecting cells of the gut and the brain axes? Here, we review the current understanding of the virus infection along the gut-brain axis for some enteric viruses and discuss the molecular mechanisms of their attenuation.

The concomitant activation of both the YAP1 co-transcription factor and RAS GTPases is a hallmark of several aggressive cancers, though the intricacies of their relationship and implications for oncogenesis are still poorly understood. This review has presented a cooperative model where YAP1 and RAS are not independently acting oncogenes but rather interdependently acting ones, with each fulfilling an essential role within the oncogenic process. YAP1 is responsible for initiating the expression of key proteins that contribute to various cancer traits. However, these proteins must often be transported into the cytoplasm to exert their effects. We suggest that oncogenic RAS actually facilitates this transport, enabling the phosphorylation and subsequent activation of the nuclear transporter XPO1 (aka Exportin1). This mechanism is particularly crucial for anti-apoptotic proteins. Instead of being sequestered within the nucleus in an ineffective state, these proteins are rather shuttled into the cytoplasm. Within the cytoplasm, they can effectively inhibit apoptosis, undermining by these means the efficacy of chemotherapeutic agents designed to induce cell death in cancer cells. Therefore, a clearer understanding of the oncogenic partnership between RAS and YAP1 will likely provide new insights into the molecular underpinnings of cancer and highlight as well potential targets for therapeutic interventions designed to disrupt this pernicious interaction.