Lysine Malonylation Is Elevated in Type 2 Diabetic Mouse Models and Enriched in Metabolic Associated Proteins

Abstract

Protein lysine malonylation, a newly identified protein post-translational modification (PTM), has been proved to be evolutionarily conserved and is present in both eukaryotic and prokaryotic cells. However, its potential roles associated with human diseases remain largely unknown. In the present study, we observed an elevated lysine malonylation in a screening of seven lysine acylations in liver tissues of db/db mice, which is a typical model of type 2 diabetes. We also detected an elevated lysine malonylation in ob/ob mice, which is another model of type 2 diabetes. We then performed affinity enrichment coupled with proteomic analysis on liver tissues of both wild-type (wt) and db/db mice and identified a total of 573 malonylated lysine sites from 268 proteins. There were more malonylated lysine sites and proteins in db/db than in wt mice. Five proteins with elevated malonylation were verified by immunoprecipitation coupled with Western blot analysis. Bioinformatic analysis of the proteomic results revealed the enrichment of malonylated proteins in metabolic pathways, especially those involved in glucose and fatty acid metabolism. In addition, the biological role of lysine malonylation was validated in an enzyme of the glycolysis pathway. Together, our findings support a potential role of protein lysine malonylation in type 2 diabetes with possible implications for its therapy in the future. Molecular & Cellular

SIRT5 Regulates both Cytosolic and Mitochondrial Protein Malonylation with Glycolysis as a Major Target

“…Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), which converts glyceraldehyde 3-phosphate to glycerate 1,3-bisphosphate, was the second most dynamically regulated glycolytic enzyme (WT/KO ratio = 6.4) (Figure 4C). Interestingly, Du et al (2015) recently reported hypermalonylation of Aldolase B in db/db mouse liver, though its regulation by SIRT5 was not addressed.…”

“…Intra-cellular concentrations of malonyl-CoA are highly dynamic; during fasting or in livers of diabetic rats, levels are reduced by approximately 50% (McGarry et al, 1978; Guynn et al, 1972). Du et al (2015) recently reported the hypermalonylation of liver proteins in a mouse model of diabetes and the potential for this malonylation to inhibit glycolytic enzyme function. Here, we directly demonstrate both a potential role for malonyl-CoA as a negative feedback regulator of glycolysis and a role for SIRT5 in limiting this negative feedback.…”

“…Three studies have examined the distribution of lysine malonylation sites: Peng et al (2011) identified 25 peptides from 17 proteins, Bao et al (2013) reported the identification of another 361 malonylated proteins using a chemical probe MalAM-yne, and Du et al (2015) recently reported 573 malonylation sites over 268 proteins in db/db mice commonly used to model type 2 diabetes. The Peng and Bao studies were conducted in HeLa cell lines, while Du reported malonylation sites present in vivo.…”

Mal-Lys: prediction of lysine malonylation sites in proteins integrated sequence-based features with mRMR feature selection

“…Among the 20 types of natural amino acids occurred in proteins, lysine is one of the most heavily modified residues12. Recent discoveries of multiple types of new protein lysine acylations, such as malonylation, succinylation, and glutarylation, have greatly expanded our understanding of the types of protein PTMs13456789. Because malonyl, succinyl and glutaryl groups contain a negatively charged carboxyl group, the three types of acidic lysine modifications are structurally similar and have the potential to regulate different proteins in different pathways5.…”

“…A recent study characterized that lysine malonylation regulates the glycolytic flux by modifying mouse glyceraldehyde 3-phosphate dehydrogenase (GAPDH) at K184 to inhibit its enzymatic activity3. Also, using the liver tissues of db / db and ob / ob mice, it was observed that malonylation plays a potential role in type 2 diabetes, whereas further bioinformatic analysis of the proteomic results revealed the enrichment of malonylated proteins in metabolic pathways, especially the pathways of glucose and fatty acid metabolisms4.…”