Regulation and mechanism of Gm49394 on islet-β cell apoptosis

To explore the potential role and underlying mechanism of the functionally uncharacterized gene Gm49394 on regulating β-cell apoptosis under diabetic conditions.

The expression and translational activity of Gm49394 in pancreatic β-cell lines and non-β-cell lines were validated using RNA fluorescence in situ hybridization（RNA-FISH）, quantitative real-time PCR（qPCR）, Western blotting, and immunofluorescence（IF）assay. The β-cell lines（NIT-1/Min6）with Gm49394 overexpression or knockdown were constructed. The proliferation, apoptosis, mitochondrial function, as well as oxidative stress and endoplasmic reticulum stress markers in these β-cell lines under physiological homeostasis or pathological stress conditions, such as high glucose（30 mmol/L）, inflammation（10 ng/mL IFN-γ alone or combined with 10 ng/mL IL-6）, and hydrogen peroxide（100 μmol/L H₂O₂）were detected by flow cytometry and Western blotting.

RNA-FISH and qPCR indicated that Gm49394 was specifically expressed in pancreatic β-cell lines and up-regulated under high glucose or inflammatory stimulation. IF assay and Western blotting showed that Gm49394 had protein-coding activity. Flow cytometry and Western blotting identified that Gm49394 overexpression did not affect β-cell proliferation, but promoted β-cell apoptosis and increased reactive oxygen species（ROS）and mitochondrial superoxide（MitoSOX）levels in β cells under physiological homeostasis or pathological stress conditions（P<0. 05）. Under physiological conditions, Gm49394 knockdown failed to induce significant alterations on β-cell apoptosis, ROS, or MitoSOX levels. Under pathological stress conditions, Gm49394 knockdown significantly suppressed β-cell proliferation, apoptosis, as well as oxidative and endoplasmic reticulum stress（P<0. 05）.

Gm49394 may promote β-cell apoptosis via oxidative stress and endoplasmic reticulum stress.