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torsdag 2 augusti 2018

SIRT4 "viimeinen palapeliosanen mitokondriaalisissa sirtuiineissa"

https://www.researchgate.net/publication/326513807_SIRT4_is_the_last_puzzle_of_mitochondrial_sirtuins



Abstract
Sirtuins are recently redefined as a family of nicotinamide adenine dinucleotide (NAD)-dependent deacylases. Sirtuins in mammals including human have seven members, which are SIRT1-7. Compared to other sirtuin members, not much study is focused on mitochondrial sirtuins (SIRT3-5). In mitochondrial sirtuins, SIRT4 was the last of less well-understood mitochondrial sirtuins especially for its robust enzymatic activity. This makes SIRT4 become the last puzzle of mitochondrial sirtuins, and thus brings some obstacles for studying SIRT4 biological functions or developing SIRT4 modulators. In this review, we will summarize and discuss the current findings for substrates, biological functions and possible enzymatic activities of SIRT4. The purpose of this review is to facilitate in discovering the robust enzymatic activity of SIRT4 and eventually finish this last puzzle of mitochondrial sirtuins.


Protein
NAD-dependent protein lipoamidase sirtuin-4, mitochondrial
Gene SIRT4
Function
Acts as NAD-dependent protein lipoamidase, ADP-ribosyl transferase and deacetylase. Catalyzes more efficiently removal of lipoyl- and biotinyl- than acetyl-lysine modifications. Inhibits the pyruvate dehydrogenase complex (PDH) activity via the enzymatic hydrolysis of the lipoamide cofactor from the E2 component, DLAT, in a phosphorylation-independent manner (PubMed:25525879). Catalyzes the transfer of ADP-ribosyl groups onto target proteins, including mitochondrial GLUD1, inhibiting GLUD1 enzyme activity. Acts as a negative regulator of mitochondrial glutamine metabolism by mediating mono ADP-ribosylation of GLUD1: expressed in response to DNA damage and negatively regulates anaplerosis by inhibiting GLUD1, leading to block metabolism of glutamine into tricarboxylic acid cycle and promoting cell cycle arrest (PubMed:16959573, PubMed:17715127). In response to mTORC1 signal, SIRT4 expression is repressed, promoting anaplerosis and cell proliferation. Acts as a tumor suppressor (PubMed:23562301, PubMed:23663782). Also acts as a NAD-dependent protein deacetylase: mediates deacetylation of 'Lys-471' of MLYCD, inhibiting its activity, thereby acting as a regulator of lipid homeostasis (By similarity). Does not seem to deacetylate PC (PubMed:23438705). Controls fatty acid oxidation by inhibiting PPARA transcriptional activation. Impairs SIRT1:PPARA interaction probably through the regulation of NAD+ levels (PubMed:24043310). Down-regulates insulin secretion. UniRule annotation 7 Publications
 

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