Regulation of Cell Death by Transfer RNA

Abstract

Both transfer RNA (tRNA) and cytochrome c are essential molecules for the survival of cells. tRNA decodes mRNA codons into amino-acid-building blocks in protein in all organisms, whereas cytochrome c functions in the electron transport chain that powers ATP synthesis in mitochondrion-containing eukaryotes. Additionally, in vertebrates, cytochrome c that is released from mitochondria is a potent inducer of apoptosis, activating apoptotic proteins (caspases) in the cytoplasm to dismantle cells. A better understanding of both tRNA and cytochrome c is essential for an insight into the regulation of cell life and death. A recent study showed that the mitochondrion-released cytochrome c can be removed from the cell-death pathway by tRNA molecules. The direct binding of cytochrome c by tRNA provides a mechanism for tRNA to regulate cell death, beyond its role in gene expression. The nature of the tRNA-cytochrome c binding interaction remains unknown. The questions of how this interaction affects tRNA function, cellular metabolism, and apoptotic sensitivity are unanswered. Investigations into the critical issues raised above will improve the understanding of tRNA in the fundamental processes of cell death and metabolism. Such knowledge will inform therapies in cell death-related diseases.