Autophagy eliminates ER membrane reorganization induced by Bcl-2 inhibitor in HeLa cells

Pharmacological activation of TRPML1 enhances autophagy regulating hypertonicity and TGF-β-induced EMT in proximal tubular epithelial cells

Proximal tubular epithelial cells (PTECs) are central to maintaining kidney homeostasis. Under pathological conditions, such as ischemia or inflammation, PTECs promote profibrotic signals, including transforming growth factor (TGF)-β, and undergo epithelial-mesenchymal transition (EMT). EMT is characterized by decreased epithelial markers (e.g., E-cadherin) and increased mesenchymal markers (e.g., α-smooth muscle actin [α-SMA]), which promote myofibroblast activation and fibrosis progression. We previously demonstrated that hyperosmotic stress, characterized by elevated extracellular solute concentrations, induces EMT in PTECs. However, we observed that hyperosmotic stress simultaneously activates autophagy, a cellular process that has antagonistic effects on EMT, primarily mediated by transient receptor potential mucolipin 1 (TRPML1). However, the interplay between hyperosmotic stress-induced EMT and autophagy remains unclear. This study examined whether enhancing autophagy via TRPML1 activation could modulate EMT under hyperosmotic stress. Using the TRPML1 agonist ML-SA1, we observed a significantly increased autophagic flux, indicated by elevated LC3-II levels, without cytotoxic effects. Under hyperosmotic conditions, ML-SA1 further amplified autophagic flux in PTECs compared to hyperosmotic stress alone. Notably, this enhanced autophagy suppressed EMT by maintaining E-cadherin expression and reducing α-SMA levels. Furthermore, the ML-SA1-mediated autophagy enhancement attenuated EMT and profibrotic factor production in TGF-β-treated cells, suggesting a broader protective role beyond hyperosmotic stress. These findings reveal a novel interaction between hyperosmotic stress-induced autophagy and EMT, emphasizing TRPML1 activation's therapeutic potential to mitigate PTEC injury and fibrosis progression.

M10, a novel derivative of Myricetin, prevents ulcerative colitis and colorectal tumor through attenuating robust endoplasmic reticulum stress

Chronic gut inflammation disposes to an increased risk of colitis-associated cancer. Chemoprevention is an attractive complementary strategy. We aimed to evaluate the chemopreventive effects of M10, a novel derivative of Myricetin, in the murine azoxymethane/dextran sodium sulfate model. Oral administration of M10 at 50-100 mg/kg once a day for consecutive 12 weeks significantly prevented ulcerative colitis (UC) and colorectal tumor. Pathological analysis of intestines showed that M10 reduced the degree of chronic inflammation and prevented the progression of colorectal tumorigenesis. Flow cytometry analysis of the immunocytes isolated from intraepithelial and lamina propria showed that M10 prevented the infiltration of myeloid-derived suppressor cells and increased CD8+T and CD4+T cells in colorectal tissues. Enzyme-linked immunosorbent analysis revealed the reduction of pro-inflammatory mediators granulocyte-macrophage colony-stimulating factor/macrophage colony-stimulating factor, IL-6 and TNF-α in colonic mucosa. Western blot assay also showed M10 prevention of the NF-κB/IL-6/STAT3 pathways and the biomarkers of inflammation and colorectal tumorigenesis. Electron microscopy analysis revealed that M10 prevent robust endoplasmic reticulum (ER) stress-induced autophagy in inflamed colonic mucosal cells. In conclusion, oral administration of Myricetin derivative M10 exerts chemoprevention of UC and colorectal tumor in mice. The mechanism of chemoprevention is associated with the reduction of biomarkers of chronic inflammation and proliferation through attenuating robust ER stress in inflamed colonic mucosal cells. M10 exerts chemoprevention activity without evidence of toxicity in mice. These results justify further evaluation of M10 in clinical trials. M10 could develop a promising regimen in the chemoprevention of colitis and colorectal cancer.