Cell cycle-dependent mitochondrial biogenesis and dynamics in mammalian cells.

During cell cycle progression and division, how cells coordinate mitochondrial biogenesis, distribution, and partitions remains to be clarified. Here, we show that mitochondrial mass and mitochondrial membrane potential increased from early G(1) to G(1)/S and further gradually elevated to mitotic phase, indicating that mitochondrial biogenesis begins from early G(1) phase. In addition, mitochondrial DNA contents appeared to increase from G(1)/S to G(2) phase during which a slight but consistent increase of NRF-1 level was observed. However, other transcriptional factors regulating mitochondrial biogenesis, mtTFA and PRC, were not changed. During interphase, heterogeneous mitochondrial population with different morphology and sizes were observed but reorganized into relatively homogeneous population of mitotic cells. Moreover, microtubule and dynein complex, p150(Glued) and dynein intermediate chain, strongly associate with mitochondria during interphase but dissociated from them during mitosis. Taken together, our results suggest that mitochondrial biogenesis and dynamics are tightly regulated during cell cycle progression.