hMTERF4 knockdown in HeLa cells results in sub-G1 cell accumulation and cell death.

Mitochondrial activity and cell energy status play important roles in the regulation of cell cycle and cell proliferation. Regulation of mitochondrial gene expression is crucial for mitochondrial activity regulation. The mitochondrial transcription termination factor (MTERF) family is a group of important mitochondrial transcription regulatory factors. It has been demonstrated that MTERF1-3 are involved in the regulation of mitochondrial gene transcription and oxidative phosphorylation. However, the function of the newest member MTERF4 has not been characterized. In this study, human MTERF4 full-length open reading frame was cloned, and the protein structure prediction revealed that hMTERF4 protein contained leucine-zipper motifs, which is similar to human MTERF1-3. The expressed pMTERF4-green fluorescence fusion protein in HeLa cells localized the mitochondria. (3(4,5)dimethylthiahiazo(zy1)3,5diphenytetrazoliumromide) (MTT) proliferation assay and flow cytometry analysis showed that hMTERF4 knockdown induced sub-G1 phase cells accumulation, whereas its overexpression promoted cell proliferation. Furthermore, double staining with Annexin V and PI revealed that hMTERF4 knockdown increased necrosis but not apoptosis. In conclusion, our data suggested that hMTERF4 is an essential factor for cell proliferation, which is probably modulated by mitochondrial transcription to promote cell proliferation.