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Skin and its cell components continuously subject to extrinsic and intrinsic mechanical forces and are mechanical sensitive. Disturbed mechanical homeostasis may lead to changes in skin functions. Gravity is the integral mechanical force on the earth, however, how gravity contributes to the maintenance of skin function and how microgravity in space affects the wound healing are poorly understood. Here, using microgravity analogs, we show that simulated microgravity (SMG) inhibits the healing of cutaneous wound and the accumulation of dermal fibroblasts in the wound bed. In vitro, SMG inhibits the migration of human foreskin fibroblast cells (HFF‐1), and decreases the F‐actin polymerization and YAP (yes‐associated protein) activity. The SMG‐inhibited migration can be recovered by activating YAP or F‐actin polymerization using lysophosphatidic acid (LPA) or jasplakinolide (Jasp), suggesting the involvement of F‐actin/YAP signaling pathway in this process. In SMG rats, LPA treatment improves the cutaneous healing with increased dermal fibroblasts in the wound bed. Together, our results demonstrate that SMG attenuates the cutaneous wound healing by inhibiting dermal fibroblast migration, and propose the crucial role of F‐actin/YAP mechano‐transduction in the maintenance of skin homeostasis under normal gravity, and YAP as a possible therapeutic target for the skin care of astronauts in space. [ABSTRACT FROM AUTHOR]

Studies have shown that bone marrow-derived mesenchymal stem cells (BMSCs) can differentiate into dermal fibroblasts to participate in skin-repairing. However, at present, little is known about how microgravity affects dermal fibroblastic differentiation of BMSCs in space. The aim of this study was to investigate the effect of simulated microgravity (SMG) on the differentiation of BMSCs into dermal fibroblasts and the related molecular mechanism. Here, using a 2D-clinostat device to simulate microgravity, we found that SMG inhibited the differentiation and suppressed the Wnt/β-catenin signaling and phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2). After upregulating the Wnt/β-catenin signaling with lithium chloride (LiCl) treatment, we found that the effect of the differentiation was restored. Moreover, the Wnt/β-catenin signaling was upregulated when phosphorylation of ERK1/2 was activated with tert-Butylhydroquinone (tBHQ) treatment. Taken together, our findings suggest that SMG inhibits dermal fibroblastic differentiation of BMSCs by suppressing ERK/β-catenin signaling pathway, inferring that ERK/β-catenin signaling pathway may act as a potential intervention target for repairing skin injury under microgravity conditions. [ABSTRACT FROM AUTHOR]

Folate-mediated one-carbon metabolism (FOCM) plays a vital role in supporting cancer cells hyperproliferation. Malignant cells, including nasopharyngeal carcinoma (NPC) cells, are characterized by rapid proliferation and thus need large numbers of nucleotides and nutrients generated from FOCM. However, the mechanism and key genes involved in FOCM playing a vital role in NPC progression are still unclear. This study aimed to find out the key gene, and its functions in NPC and explore the potential mechanism. Bioinformatics analysis based on TCGA and GSEA database were performed to screen the key FOCM related gene in HNSCC. The effects of MTHFD2 on cell proliferation, apoptosis and migration were conducted through MTHFD2 knockdown cell lines in vitro experiments. Cell proliferation was explored by CCK8 assay and colony formation assay. Cell apoptosis was tested through flow cytometry. Transwell migration assay was performed to study the cell migration. The potential pathway was explored by RNA-seq and the ERK inhibitor SCH772984 and the ERK activator tBHQ were applied to verify the effect of MTHFD2 in NPC via the ERK pathway. Finally, xenograft tumor model was used to explore the tumorigenicity of NPC cells in vivo and IHC was performed to study the expression of related proteins. MTHFD2 was highly expressed in NPC and associated with a poor prognosis. MTHFD2 knockdown inhibited the proliferation, migration and induced apoptosis of NPC cells in vitro. In consistent with cellular results, knockdown of MTHFD2 suppressed the tumorigenicity of NPC cells in vivo. MAPK pathway was enriched among DEGs between MTHFD2 knockdown cells and control cells. And the level of p-ERK1/2 and p-p38 MAPK was decreased in MTHFD2 knockdown cells and xenograft tumors of MTHFD2 knockdown cells. Furthermore, the application of the selective ERK inhibitor SCH772984 and the ERK activator tBHQ confirmed that MTHFD2-knockdown inhibited the proliferation and migration of NPC cells via the ERK signaling pathway. MTHFD2 was up-regulated in NPC tissues and its high expression was linked to a poor prognosis. Knockdown of MTHFD2 inhibited proliferation and migration of NPC cells through the ERK signaling pathway, which may provide new clues and targets for the treatment of NPC. • MTHFD2 is upregulated in nasopharyngeal carcinoma and is associated with poor prognosis. • Knockdown of MTHFD2 inhibits proliferation and migration of nasopharyngeal carcinoma cells. • MTHFD2-knockdown suppresses the ERK signaling pathway. [ABSTRACT FROM AUTHOR]

Hepatocyte necroptosis is a critical event in the progression of non-alcoholic fatty liver disease (NAFLD). Obstructive sleep apnea hypopnea syndrome (OSAHS) and chronic intermittent hypoxia (CIH) may be linked with the pathogenesis and the severity of NAFLD. However, the potential role of necroptosis in OSAHS-associated NAFLD has not been evaluated. The present study investigated whether IH could affect NAFLD progression through promoting receptor-interacting protein kinase-3 (RIPK3)-dependent necroptosis, oxidative stress, and inflammatory response, and further elucidated the underlying molecular mechanisms. LO2 cells were treated with palmitic acid (PA) and subjected to IH, and necroptosis, oxidative stress, and inflammation were assessed. The high-fat choline-deficient (HFCD)-fed mouse model was also used to assess the effects of CIH in experimental NAFLD in vivo. In this study, we found that RIPK3-mediated necroptosis was activated both in the PA plus IH-treated LO2 cells and liver of HFCD/CIH mice, and which could trigger oxidative stress and inflammatory response by decreasing Nrf2 and increasing p-P65. RIPK3 downregulation significantly reduced hepatocyte necroptosis, and ameliorated oxidative stress and inflammation through modulating Nrf2/NFκB pathway in vitro and vivo. Similarly, pretreatment with TBHQ, an activator of Nrf2, effectively blocked the generation of oxidative productions and inflammatory cytokines. In addition, RIPK3 inhibitor GSK-872 or TBHQ administration obviously alleviated hepatic injury, including histology, transaminase activities, and triglyceride contents in vivo. IH aggravates NAFLD via RIPK3-dependent necroptosis-modulated Nrf2/NFκB signaling pathway, and which should be considered as a potential therapeutic strategy for the treatment of NAFLD with OSASH. • IH aggravates NAFLD via RIPK3-dependent necroptosis and Nrf2/NFκB pathway-mediated oxidative stress and inflammation. • RIPK3 inhibition attenuates necroptosis, oxidative stress, and inflammatory response in NAFLD progression caused by IH. • Nrf2/NFκB activation is regarded as the downstream signal of RIPK3-dependent necroptosis. [ABSTRACT FROM AUTHOR]