The transcriptional repressor forkhead box N3 (FOXN3) has been reported to suppress pulmonary fibrosis by inhibiting Smad transcriptional activity. However, FOXN3 becomes unstable in response to profibrotic stimuli. This study identifies poly(ADP-ribose) polymerase–1 (PARP1) as a stabilizing partner of FOXN3, preventing its degradation by blocking p38-mediated phosphorylation. Lung-specific knockout (KO) of PARP1 promotes the development of pulmonary fibrosis by reducing the abundance of FOXN3. Conditional overexpression of FOXN3 notably mitigates pulmonary fibrosis resulting from PARP1 KO by impeding Smad signaling, underscoring the critical role of the PARP1-FOXN3 axis in pulmonary fibrosis. Mechanistically, p38 is a Smad response gene that is transcriptionally repressed by the PARP1/FOXN3 complex. The disruption of PARP1 or FOXN3 increases p38 expression, which in turn facilitates FOXN3 degradation through a feedback mechanism. This cascade activates Smad signaling, leading to a profibrotic response and myofibroblast activation. Notably, levels of PARP1 and FOXN3 are significantly reduced in patients with pulmonary fibrosis, highlighting PARP1’s crucial role in suppressing the disease by regulating FOXN3-mediated Smad signaling.

Menstrual blood-derived endometrial stem cells (MenSCs) emerge as an ideal source for cell-based treatment in regenerative medicine and immunotherapy. However, the major obstacle is the low survival rate in tissues and the limited expansion number. Autophagy is an intracellular metabolic self-degradative process which plays important roles in normal cellular division and survival, and the present study aimed to explore the related mechanisms between autophagy and survival of MenSCs in vitro and in vivo. The MenSCs were obtained from menstrual blood procured from healthy female donors. In vitro, MenSCs were exposed to rapamycin and Earle’s balanced salts solution (EBSS). We evaluated the MenSCs immunophenotypic cell cycle distribution by propidium iodide (PI) staining and cell apoptosis by Annexin V/PI staining as well as their proliferative potential by the MTT assay. We also assessed the expression of genes associated with the cell cycle and Gsk3β signaling pathway by western blot analysis. We depressed Atg5 and Gsk3β expression by short hairpin RNA (shRNA) and undertook the experiments. Moreover, the labeled MenSCs were observed and counted with DiI after transplantation into the mice via the tail vein by microscopy in vivo. In vitro, rapamycin and starvation induced autophagy of MenSCs. Hyperactive autophagy significantly induced G0/G1 arrest and slightly promoted apoptosis of MenSCs. Meanwhile, autophagy could stimulate p-GSK3β expression in MenSCs. Further, knockdown GSK3β can accelerate the proliferation of MenSCs by shRNA and CHIR99021. Moreover, the shGSK3β MenSCs showed strong proliferative activity in vitro and in vivo. Our results indicate that autophagy induced G0/G1 arrest and apoptosis of MenSCs via GSK3β/β-catenin pathway. Inhibiting autophagy or reduced GSK3β levels may improve survival rate in vivo, thus playing roles in MenSCs therapy.

Non‐alcoholic fatty liver disease (NAFLD), an increasingly devastating human disorder, is characterized by intrahepatic fat accumulation. Although important progress has been made in understanding NAFLD, the fundamental mechanisms involved in the pathogenesis of NAFLD have not been fully explained. The endo‐lysosomal trafficking network is central to lipid metabolism, protein degradation and signal transduction, which are involved in a variety of diseases. In recent years, many genes and pathways in the endo‐lysosomal trafficking network and involved in lysosomal biogenesis have been associated with the development and progression of NAFLD. Mutations of these genes and impaired signalling lead to dysfunction in multiple steps of the endo‐lysosomal network (endocytic trafficking, membrane fusion and lysosomal degradation), resulting in the accumulation of pathogenic proteins. In this review, we will focus on how alterations in these genes and pathways affect endo‐lysosomal trafficking as well as the pathophysiology of NAFLD.

The sterol regulatory element-binding transcription factor 1 (SREBP-1) plays a crucial role in the transcriptional regulation of lipogenic response genes, thereby contributing to the development of non-alcoholic fatty liver disease (NAFLD). However, the modulation of SREBP-1 transcriptional activity remains incompletely understood. Here, we report that the transcription factor FOXN3 interacts with the KU70/KU80/SREBP-1 complex, facilitating the recruitment of SREBP-1 for the transcriptional activation of lipogenic response genes. Hepatocyte-specific knockout of FOXN3 significantly alleviates the pathological progression of NAFLD by suppressing fatty acid and cholesterol synthesis. Furthermore, phosphorylation of FOXN3 at the S83 and S85 residues disrupts the stability of the KU70/KU80/FOXN3/SREBP-1 complex, which is required for SREBP-1 transcriptional activity. This disruption consequently impedes the progression of NAFLD. Clinical investigations reveal that FOXN3, KU80, and SREBP-1 co-target the promoters of lipogenic response genes in fatty liver tissues from patients. Notably, phosphorylation levels of FOXN3 at S83 and S85 are significantly reduced in fatty liver tissues compared to normal samples. This reduction enhances the enrichment of the FOXN3/SREBP-1 complex at the promoters of lipogenic response genes during the progression of NAFLD. Our study underscores the critical role of FOXN3 in maintaining the intact KU70/KU80/FOXN3/SREBP-1 complex, which is essential for SREBP-1-mediated metabolic disorders.