TRIM34 localizes to the mitochondria and mediates apoptosis through the mitochondrial pathway in HEK293T cells

Abstract

Tripartite motif 34 (TRIM34) is a member of TRIM family that can be highly induced by type I Interferon. Currently little is known about the subcellular localization and biological function of TRIM34. In the present study, confocal microscope assay showed that TRIM34 proteins were mainly distributed in the cytoplasm and part of TRIM34 proteins were localized to the mitochondria in human embryonic kidney 293T (HEK293T) cells. Western blot results demonstrated FLAG-TRIM34 could also be identified in the mitochondrial fractions of HEK293T cells transfected with the 5′FLAG-pcDNA3.1-TRIM34 vector. The CCK-8 assay further demonstrated that TRIM34 significantly decreased the viability of HEK293T cells. Nevertheless, TRIM34 had no apparent effect on the cell cycle distribution. Interestingly, flow cytometry showed that TRIM34 could obviously induce apoptosis in HEK293T cells. Moreover, we discovered that TRIM34 promoted apoptosis by inducing the loss of mitochondrial membrane potential (MMP) in HEK293T cells, leading to the release of cytochrome c from mitochondia. In short, these results demonstrate that TRIM34 proteins can localize to the mitochondria and induce apoptosis via the depolarization of MMP in HEK293T cells.