Acetylation of malate dehydrogenase 1 promotes adipogenic differentiation via activating its enzymatic activity.
ABSTRACT Acetylation is one of the most crucial post-translational modifications that affect protein function. Protein lysine acetylation is catalyzed by acetyltransferases, and acetyl-CoA functions as the source of the acetyl group. Additionally, acetyl-CoA plays critical roles in maintaining the balance between carbohydrate metabolism and fatty acid synthesis. Here, we sought to determine whether lysine acetylation is an important process for adipocyte differentiation. Based on an analysis of the acetylome during adipogenesis, various proteins displaying significant quantitative changes were identified by LC-MS/MS. Of these identified proteins, we focused on malate dehydrogenase 1 (MDH1). The acetylation level of MDH1 was increased up to 6-fold at the late stage of adipogenesis. Moreover, overexpression of MDH1 in 3T3-L1 preadipocytes induced a significant increase in the number of cells undergoing adipogenesis. The introduction of mutations to putative lysine acetylation sites showed a significant loss of the ability of cells to undergo adipogenic differentiation. Furthermore, the acetylation of MDH1 dramatically enhanced its enzymatic activity and subsequently increased the intracellular levels of NADPH. These results clearly suggest that adipogenic differentiation may be regulated by the acetylation of MDH1 and that the acetylation of MDH1 is one of the cross-talk mechanisms between adipogenesis and the intracellular energy level.
SourceAvailable from: Hyo Jin Lee[Show abstract] [Hide abstract]
ABSTRACT: Annexin A2 (ANXA2) expression is highly upregulated in many types of cancer. Although cell surface localization of ANXA2 has been reported to have a critical role in the progression and metastasis of a variety of tumors, including pancreatic cancer, the biological role of intracellular ANXA2 is not fully understood. Herein the role of intracellular ANXA2 was investigated in a pancreatic cancer cell line. We first determined whether ANXA2 is involved in NF-κB signaling pathways. ANXA2 bound to the p50 subunit of NF-κB in a calcium-independent manner, and the ANXA2-p50 complex translocated into the nucleus. Furthermore, ANXA2 increased the transcriptional activity of NF-κB in both the resting and activated states and upregulated the transcription of several target genes downstream of NF-κB, including that encoding interleukin (IL)-6, which contributes to anti-apoptotic signaling. In Mia-Paca2 cells, we determined the effects of wild-type ANXA2 and an ANXA2 mutant, Y23A, which suppresses the cell surface localization, on upregulation of NF-κB transcriptional activity and secretion of IL-6. Both wild-type and Y23A ANXA2 induced anti-apoptotic effects in response to treatment with tumor necrosis factor-α or gemcitabine. Based on these results, we suggest that ANXA2 mediates resistance to gemcitabine by directly increasing the activity of NF-κB. Collectively, these data may provide additional information about the biological role of ANXA2 in pancreatic cancer and suggest that ANXA2 is a potential biomarker for the drug resistance phenotype and a candidate therapeutic target for the treatment of pancreatic cancer.Cell Death & Disease 01/2015; 6(1):e1606. DOI:10.1038/cddis.2014.558 · 5.18 Impact Factor
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ABSTRACT: Protein lysine succinylation, an emerging protein post-translational modification widespread among eukaryotic and prokaryotic cells, represents im portant regulator of cellular processes. However, the extent and function of lysine succinylation in Mycobacterium tuberculosis, especially extensively drug-resistant (XDR) strain, remain elusive. Combining protein/peptide prefractionation, immunoaffinity enrichment, and LC - MS/MS analysis, a total of 686 succinylated proteins and 1739 succinylation sites of M. tuberculosis were identified, representing the first global profiling of M. tuberculosis lysine succinylation. The identificated succinylated proteins are involved in a variety of cellular functions such as metabolic processes, tr anscription, translation and stress responses, and exhibit different subcellular localization via GO, pr otein interaction network and other bioinformatic analysis. Notably, proteins involved in protein biosynthesis and carbon metabolism are preferred targets of lysine succinylation. Moreover, two prevalent sequence patterns: EK suc and K*****K suc, can be found around the succinylation sites. There are 109 lysine-succinylated homologs in E. coli , suggesting highly conserved succinylated proteins. Su ccinylation was found to occur at the active sites predicted by Prosite signature incl uding Rv0946c, indicating that lysine succinylation may affect their activities. There are extensive overlapping betwee n acetylation sites and succinylation sites in M.tuberculosis . Many M. tuberculosis metabolic enzymes and antibiotic resistance proteins were succinylated. This study provides a basis for furthe r characterization of the pathophysiological role of lysine succinylation in M.tuberculosis .Journal of Proteome Research 11/2014; 14(1). DOI:10.1021/pr500859a · 5.00 Impact Factor
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ABSTRACT: Eukaryotic cells produce chemical energy in the form of ATP by oxidative phosphorylation of metabolic fuels via a series of enzyme mediated biochemical reactions. We propose that the rates of these reactions are altered, as per energy needs of the seasonal metabolic states in avian migrants. To investigate this, blackheaded buntings were photoperiodically induced with non-migratory, premigratory, migratory and post-migratory phenotypes. High plasma levels of free fatty acids, citrate (an intermediate that begins TCA cycle) and malate dehydrogenase (mdh, an enzyme involved at the end of TCA cycle) confirmed increased availability of metabolic reserves and substrates to TCA cycle during the premigratory and migratory states, respectively. Further, daily expression pattern of genes coding for enzymes involved in the oxidative decarboxylation of pyruvate to acetyl-CoA (pdc and pdk) and oxidative phosphorylation in the TCA cycle (cs, ogdh, sdhd and mdh) was monitored in the hypothalamus and liver. Reciprocal relationship between pdc and pdk expressions conformed with the altered requirements of acetyl-CoA for TCA cycle in different metabolic states. Except pdk, all genes had a daily expression pattern, with high mRNA expression during the day in the premigratory/migratory phenotypes, and at night (cs, odhg, sdhd and mdh) in the nonmigratory phenotype. Differences in mRNA expression patterns of pdc, sdhd and mdh, but not of pdk, cs and odgh, between the hypothalamus and liver indicated a tissue dependent metabolism in buntings. These results suggest the adaptation of oxidative phosphorylation pathway(s) at gene levels to the seasonal alternations in metabolism in migratory songbirds. Copyright © 2015 Elsevier Inc. All rights reserved.Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology 01/2015; 184. DOI:10.1016/j.cbpa.2015.01.011 · 2.37 Impact Factor