DDX4
Description
The DDX4 (DEAD-box helicase 4) is a protein-coding gene located on chromosome 5.
Helicases are essential enzymes in all organisms, responsible for unwinding and separating nucleic acid strands. They are motor proteins that utilize ATP hydrolysis to move along the nucleic acid backbone and break hydrogen bonds between complementary base pairs. Helicases are involved in numerous cellular processes, including DNA replication, transcription, translation, recombination, DNA repair, and ribosome biogenesis. The human genome contains 95 non-redundant helicases, with approximately 1% of eukaryotic genes encoding for helicases. These helicases are categorized into RNA helicases and DNA helicases, playing crucial roles in various cellular processes. Some specialized helicases contribute to the immune system by sensing viral nucleic acids during infection.
DDX4 is an ATP-dependent RNA helicase that plays a critical role in spermatogenesis. It is essential for repressing transposable elements, preventing their mobilization, and maintaining germline integrity. DDX4 acts through the piRNA metabolic pathway, which involves the formation of complexes composed of piRNAs and Piwi proteins to silence transposons via methylation. DDX4 is also involved in the production of secondary piRNAs in fetal male germ cells through a ping-pong amplification cycle. Moreover, DDX4 is required for PIWIL2 slicing-triggered piRNA biogenesis, where its helicase activity enables the utilization of cleavage fragments generated by PIWIL2 for the processing of pre-piRNAs into mature piRNAs. These functions are essential for the proper development and function of male germ cells.
DDX4 is also known as VASA.
