MARCH6 Confers Protection Against Endoplasmic Reticulum Autophagy in Gliomas by Destabilizing FAM134B

This study probed the mechanism of MARCH6 in endoplasmic reticulum autophagy (ER-phagy) during glioma development by regulating FAM134B stability. MARCH6 and FAM134B expression levels were measured in glioma tissues. A comparative analysis was conducted on the correlation between clinical parameters and FAM134B expression in 46 glioma patients. FAM134B and MARCH6 were knocked down in glioma cells, followed by detection of cell viability and apoptosis, typical ER stress (ERS) markers (PERK, IRE1α, eIF2α, and CHOP), autophagy-related proteins (P62 and LC3B), and autophagosome cytoplasmic accumulation. A mouse glioma model was established for in vivo validation. MARCH6-FAM134B interaction, FAM134B ubiquitination levels, and protein stability were examined. FAM134B expression was high and MARCH6 expression was low in glioma tissues. MARCH6 induced FAM134B protein ubiquitination and degradation, reducing its stability in glioma cells. Knockdown of FAM134B reduced glioma cell survival, inhibited PERK, IRE1α, eIF2α, and CHOP expression, decreased LC3I to LC3II conversion, lowered LC3B fluorescence expression, and reduced the accumulation of autophagosomes with continuous ER structures in the cytoplasm, while enhancing apoptosis and P62 expression. This effect can be reversed by knocking down MARCH6. In vivo, FAM134B knockdown suppressed tumorigenesis in mice. MARCH6 exerts a repressive effect on ERS responses and ER-phagy in glioma cells by destabilizing FAM134B.