👤 Alberto Morgante

Familial combined hyperlipidemia (FCH) is a polygenic and multifactorial disease characterized by a variable phenotype showing increased levels of triglycerides and/or cholesterol. The aim of this study was to identify single nucleotides (SNPs) in lipid-related genes associated with FCH. Twenty SNPs in lipid-related genes were studied in 142 control subjects and 165 FCH patients after excluding patients with mutations in the LDLR gene and patients with the E2/E2 genotype of APOE. In particular, we studied the 9996G > A (rs2073658) and 11235C > T (rs3737787) variants in the Upstream Stimulatory Factor 1 gene (USF1), and the -1131T > C (rs662799) and S19W (rs3135506) variants in the Apolipoprotein A-V gene (APOA5). We found that the frequencies of these variants differed between patients and controls and that are associated with different lipid profiles. At multivariate logistic regression SNP S19W in APOA5 remained significantly associated with FCH independently of age, sex, BMI, cholesterol and triglycerides. Our results show that the USF1 and APOA5 polymorphisms are associated with FCH and that the S19W SNP in the APOA5 gene is associated to the disease independently of total cholesterol, triglycerides and BMI. However, more extensive studies including other SNPs such as rs2516839 in USF1, are required. Show less

In liver the mitochondrial sirtuin, SIRT5, controls ammonia detoxification by regulating CPS1, the first enzyme of the urea cycle. However, while SIRT5 is ubiquitously expressed, urea cycle and CPS1 are only present in the liver and, to a minor extent, in the kidney. To address the possibility that SIRT5 is involved in ammonia production also in nonliver cells, clones of human breast cancer cell lines MDA-MB-231 and mouse myoblast C2C12, overexpressing or silenced for SIRT5 were produced. Our results show that ammonia production increased in SIRT5-silenced and decreased in SIRT5-overexpressing cells. We also obtained the same ammonia increase when using a new specific inhibitor of SIRT5 called MC3482. SIRT5 regulates ammonia production by controlling glutamine metabolism. In fact, in the mitochondria, glutamine is transformed in glutamate by the enzyme glutaminase, a reaction producing ammonia. We found that SIRT5 and glutaminase coimmunoprecipitated and that SIRT5 inhibition resulted in an increased succinylation of glutaminase. We next determined that autophagy and mitophagy were increased by ammonia by measuring autophagic proteolysis of long-lived proteins, increase of autophagy markers MAP1LC3B, GABARAP, and GABARAPL2, mitophagy markers BNIP3 and the PINK1-PARK2 system as well as mitochondrial morphology and dynamics. We observed that autophagy and mitophagy increased in SIRT5-silenced cells and in WT cells treated with MC3482 and decreased in SIRT5-overexpressing cells. Moreover, glutaminase inhibition or glutamine withdrawal completely prevented autophagy. In conclusion we propose that the role of SIRT5 in nonliver cells is to regulate ammonia production and ammonia-induced autophagy by regulating glutamine metabolism. Show less

Some studies have suggested an overlap of clinical and genetic findings between essential tremor (ET) and Parkinson's disease (PD). The first genome-wide association study in ET showed a significant association with the rs9652490 SNP of the leucine-rich repeat and Ig domain containing 1 (LINGO1) gene. Since patients with PD have higher LINGO1 expression levels compared to healthy controls, and animal models of PD show elevated LINGO1 protein levels after experimentally induced damage in the striatum, it can be inferred that LINGO1 is probably involved in PD pathophysiology. In this study, we performed a genetic association analysis of the rs9652490 and rs11856808 SNPs in Italian PD patients and controls to assess the role of these variants in our population. A total of 567 patients with PD and 468 control subjects were enrolled in five Movement Disorder centers located in Central-Southern Italy. Both variants were significantly associated with PD under a recessive model of inheritance before applying the Bonferroni correction. The GG genotype of rs9652490 and the TT genotype of rs11856808 were less frequent in patients than in controls, suggesting a protective effect against the disease. However, after stringent correction, only the P-values obtained from allele and genotype comparisons of the rs11856808 SNP remained significant. Our findings suggest that LINGO1 plays a certain role in the development of PD in the Italian population and represents an interesting candidate gene responsible for PD, due to its involvement in neurological processes. Show less