RPD (disambiguation)

RPD may refer to:

HDAC3

Histone deacetylase 3 is an enzyme that in humans is encoded by the HDAC3 gene.

Function

Histones play a critical role in transcriptional regulation, cell cycle progression, and developmental events. Histone acetylation/deacetylation alters chromosome structure and affects transcription factor access to DNA. The protein encoded by this gene belongs to the histone deacetylase/acuc/apha family. It has histone deacetylase activity and represses transcription when tethered to a promoter. It may participate in the regulation of transcription through its binding with the zinc-finger transcription factor YY1. This protein can also down-regulate p53 function and thus modulate cell growth and apoptosis. This gene is regarded as a potential tumor suppressor gene.

This enzyme is involved in the coordination of commensal-bacteria-dependent intestinal homeostasis when expressed in intestinal epithelial cells.

Alternative functions

Histone deacetylases can be regulated by endogenous factors, dietary components, synthetic inhibitors and bacteria-derived signals. Studies in mice with a specific deletion of HDAC3 in intestinal epithelial cells (IECs) show a deregulated IEC’s gene expression. In these deletion-mutant mice, loss of Paneth cells, impaired IEC function and alterations in intestinal composition of commensal bacteria were observed. These negative effects were not observed in germ-free mice, indicating that the effects of the deletion are only seen in the presence of intestinal microbial colonization. But the negative effects of HDAC3 deletion are not due to the presence of an altered microbiota because normal germ-free mice colonized with the altered microbiota did not show the negative effects seen in deletion mutants.

RPD machine gun

The RPD (Russian: ручной пулемёт Дегтярёва Ruchnoy Pulemyot Degtyaryova, English: Degtyaryov hand-held machine gun) is a 7.62mm light machine gun developed in the Soviet Union by Vasily Degtyaryov for the intermediate 7.62×39mm M43 cartridge. It was created as a replacement for the DP machine gun chambered for the 7.62×54mmR round. It is a precursor of most squad automatic weapons. It was succeeded in Soviet service by the RPK.

History

Work on the weapon commenced in 1943. Three prominent Soviet engineers were asked to submit their own designs: Vasily Degtyaryov, Sergei Simonov and Alexei Sudayev. Among the completed prototypes prepared for evaluation, the Degtyaryov design proved superior and was accepted into service with the Soviet armed forces as the 7.62 mm Ручной Пулемёт Дегтярёва, PПД (RPD, Ruchnoy Pulemyot Degtyaryova or "Degtyaryov light machine gun") model 1944. Although the RPD was ready for mass production during the final stages of World War II, large scale delivery of the weapon did not begin until 1953. During the Vietnam War, the RPD served the Vietcong as their standard light machine gun.