Genetic control of differential acetylation in diabetic rats

A new view on functions of the lysine demalonylase activity of SIRT5

AIMS

The specificity of the lysine demalonylation substrates of the pharmaceutically attractive tumor promoter/suppressor SIRT5 is not comprehensively clarified. The present study re-analyses publicly available data and highlights potentially pharmaceutically interesting outcomes by the use of bioinformatics.

MATERIALS AND METHODS

The interaction networks of SIRT5 malonylome from the wild-type and ob/ob (obese pre-diabetic type) mice were subjected to the pathway enrichment and gene function prediction analysis using GeneMania (3.5.2) application run under Cytoscape (3.9.1) environment.

KEY FINDINGS

The analysis in the wild-type mice revealed the involvement of SIRT5 malonylome in Eukaryotic translation elongation (ETE; the nodes EF1A1, EEF2, EEF1D, and EEF1G), Amino acid and derivative metabolism (AADM), and Selenoamino acid metabolism (SAM). The tumor promoter/suppressor activity of SIRT5 is mediated through the tumor promoter substrates included in AADM (GLUD1, SHMT1, ACAT1), and the tumor suppressor substrates involved in AADM and SAM (ALDH9A1, BHMT, GNMT). Selen stimulates the expression of SIRT5 and other sirtuins. SIRT5 in turn regulates the selenocysteine synthesis, which creates a regulatory loop. The analysis of SIRT5 malonylome in pre-diabetic ob/ob mice identifies the mTORC1 pathway as a mechanism, which facilitates SIRT5 functions. The comparison of the outcomes of SIRT5 malonylome, succinylome, and glutarylome analysis disclosed several differences.

SIGNIFICANCE

The analysis showed additional aspects of SIRT5 malonylome functions besides the control of glucose metabolism. It defined several unique substrates and pathways, and it showed differences compared to other enzymatic activities of SIRT5, which could be used for pharmaceutical benefits.

Diabetes and Its Cardiovascular Complications: Potential Role of the Acetyltransferase p300

Diabetes has been shown to accelerate vascular senescence, which is associated with chronic inflammation and oxidative stress, both implicated in the development of endothelial dysfunction. This condition represents the initial alteration linking diabetes to related cardiovascular (CV) complications. Recently, it has been hypothesised that the acetyltransferase, p300, may contribute to establishing an early vascular senescent phenotype, playing a relevant role in diabetes-associated inflammation and oxidative stress, which drive endothelial dysfunction. Specifically, p300 can modulate vascular inflammation through epigenetic mechanisms and transcription factors acetylation. Indeed, it regulates the inflammatory pathway by interacting with nuclear factor kappa-light-chain-enhancer of activated B cells p65 subunit (NF-κB p65) or by inducing its acetylation, suggesting a crucial role of p300 as a bridge between NF-κB p65 and the transcriptional machinery. Additionally, p300-mediated epigenetic modifications could be upstream of the activation of inflammatory cytokines, and they may induce oxidative stress by affecting the production of reactive oxygen species (ROS). Because several in vitro and in vivo studies shed light on the potential use of acetyltransferase inhibitors, a better understanding of the mechanisms underlying the role of p300 in diabetic vascular dysfunction could help in finding new strategies for the clinical management of CV diseases related to diabetes.

Investigation of post-translational modifications in type 2 diabetes

The investigation of post-translational modifications (PTMs) plays an important role for the study of type 2 diabetes. The importance of PTMs has been realized with the advancement of analytical techniques. The challenging detection and analysis of post-translational modifications is eased by different enrichment methods and by high throughput mass spectrometry based proteomics studies. This technology along with different quantitation methods provide accurate knowledge about the changes happening in disease conditions as well as in normal conditions. In this review, we have discussed PTMs such as phosphorylation, N-glycosylation, O-GlcNAcylation, acetylation and advanced glycation end products in type 2 diabetes which have been characterized by high throughput mass spectrometry based proteomics analysis.