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  • br Discussion Elevated blood BCAA

    2024-07-11


    Discussion Elevated blood BCAA levels are a common feature of a developed pathophysiological state characterized by obesity and IR [4]. It has been suggested that this profile is part of a panel of biomarkers able to predict the onset of more severe complications like diabetes in humans [14]. In the present study, we observed that after 2 mo of HFHS feeding, the BCAA augmentation at the fasting state was visible only after 14 d, reaching statistical significance at 1 mo. After this period, blood BCAA levels remained stable to the end of the trial. A similar profile was obtained for KA. After 2 mo of HFHS feeding, minipigs became obese with a marked hyperinsulinemia, increased HOMA-IR and dyslipidemia, and displayed elevated blood BCAA and KA levels. The fact that TG levels did not change and HDL levels were increased after this period supports the idea that minipigs were at an early stage of metabolic syndrome onset, as shown in previous studies [15], where both parameters increased after longer exposure to similar diets. Of note, we found that fasting BCAA levels were correlated with body weight, in accordance with a recent study in a human cohort [16].
    Conclusions
    Acknowledgments
    Introduction Histone lysine methyltransferases (KMTs) and demethylases (KDMs) have a central role in regulation of transcription by controlling the state of histone lysine methylation. KMTs use S-adenosylmethionine (SAM) as the methyl group donor, while KDM1 and KDM2-KDM8 family members require flavin Cilostazol dinucleotide (FAD) and α-ketoglutarate (α-KG) for demethylation, respectively (Black et al., 2012; Mosammaparast and Shi, 2010). The dependence of KMTs and KDMs on metabolic coenzymes suggests that their activities are sensitive to changes in cell metabolism, a model supported by a compelling body of evidence from recent studies (Gut and Verdin, 2013; Kaelin and McKnight, 2013; Katada et al., 2012; Lu and Thompson, 2012; Lu et al., 2012; Shyh-Chang et al., 2013; Teperino et al., 2010). This notion also suggests that, based on the principle of feedback control, KMTs and KDMs must reciprocally influence cell metabolism through transcriptional regulation of metabolic enzymes (Teperino et al., 2010) (Figure S1A). Cancer cell growth and proliferation require enhanced metabolic capacity for accumulation of biomass and replication of the genomic DNA (Cairns et al., 2011; DeBerardinis et al., 2008; Vander Heiden et al., 2009). Increased activation of the serine-glycine synthesis pathway (herein referred to as the serine pathway) through genetic (Locasale et al., 2011; Possemato et al., 2011) and epigenetic (Ding et al., 2013) mechanisms has been observed in several cancer types. In addition, recent studies have provided evidence for a key role of serine uptake in sustaining the proliferation of cancer cells (Jain et al., 2012; Labuschagne et al., 2014; Maddocks et al., 2013). The serine pathway is composed of phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), phosphoserine phosphatase (PSPH), and serine hydroxymethyltransferase (SHMT). This pathway generates biosynthetic precursors essential for the production of proteins, nucleic acids, fatty acids, and the membranes needed for cell proliferation (Amelio et al., 2014; DeBerardinis, 2011; Kalhan and Hanson, 2012; Locasale, 2013) (Figure S1B). More recently, it has been shown that serine-driven one-carbon metabolism is a major pathway of NADPH production in proliferating cells, with oxidation of 5,10-methylene-tetrahydrofolate to 10-formyl-tetrahydrofolate being coupled to reduction of NADP+ to NADPH (Fan et al., 2014). NADPH is required for reductive biosynthesis, such as the synthesis of nucleotides, amino acids and lipids, and has a pivotal role in maintaining the cellular redox balance (Schulze and Harris, 2012). Also, cancer cells can uptake exogenous serine for the production of glycine and one-carbon units through the final step of the serine pathway catalyzed by SHMT (Labuschagne et al., 2014) (Figure S1B). Thus, a better understanding of the function and regulation of the serine pathway might suggest new therapeutic approaches for inhibiting cancer metabolism and blocking cancer growth (Chaneton et al., 2012; Maddocks et al., 2013).