Melusin gene (ITGB1BP2) nucleotide variations study in hypertensive and cardiopathic patients

<p>Abstract</p> <p>Background</p> <p>Melusin is a muscle specific signaling protein, required for compensatory hypertrophy response in pressure-overloaded heart. The role of Melusin in heart function has been established both by loss and gain of function experiments in murine models. With the aim of verifying the hypothesis of a potential role of the Melusin encoding gene, <it>ITGB1BP2</it>, in the modification of the clinical phenotype of human cardiomyopathies, we screened the <it>ITGB1BP2 </it>gene looking for genetic variations possibly associated to the pathological phenotype in three selected groups of patients affected by hypertension and dilated or hypertrophic cardiomyopathy</p> <p>Methods</p> <p>We analyzed <it>ITGB1BP2 </it>by direct sequencing of the 11 coding exons and intron flanking sequences in 928 subjects, including 656 hypertensive or cardiopathic patients and 272 healthy individuals.</p> <p>Results</p> <p>Only three nucleotide variations were found in patients of three distinct families: a C>T missense substitution at position 37 of exon 1 causing an amino acid change from His-13 to Tyr in the protein primary sequence, a duplication (IVS6+12_18dupTTTTGAG) near the 5'donor splice site of intron 6, and a silent 843C>T substitution in exon 11.</p> <p>Conclusions</p> <p>The three variations of the <it>ITGB1BP2 </it>gene have been detected in families of patients affected either by hypertension or primary hypertrophic cardiomyopathy; however, a clear genotype/phenotype correlation was not evident. Preliminary functional results and bioinformatic analysis seem to exclude a role for IVS6+12_18dupTTTTGAG and 843C>T in affecting splicing mechanism.</p> <p>Our analysis revealed an extremely low number of variations in the <it>ITGB1BP2 </it>gene in nearly 1000 hypertensive/cardiopathic and healthy individuals, thus suggesting a high degree of conservation of the melusin gene within the populations analyzed.</p

Sex-specific pathways in early cardiac response to pressure overload in mice

Pressure overload (PO) first causes cardiac hypertrophy and then heart failure (HF), which are associated with sex differences in cardiac morphology and function. We aimed to identify genes that may cause HF-related sex differences. We used a transverse aortic constriction (TAC) mouse model leading to hypertrophy without sex differences in cardiac function after 2 weeks, but with sex differences in hypertrophy 6 and 9 weeks after TAC. Cardiac gene expression was analyzed 2 weeks after surgery. Deregulated genes were classified into functional gene ontology (GO) categories and used for pathway analysis. Classical marker genes of hypertrophy were similarly upregulated in both sexes (α-actin, ANP, BNP, CTGF). Thirty-five genes controlling mitochondrial function (PGC-1, cytochrome oxidase, carnitine palmitoyl transferase, acyl-CoA dehydrogenase, pyruvate dehydrogenase kinase) had lower expression in males compared to females after TAC. Genes encoding ribosomal proteins and genes associated with extracellular matrix remodeling exhibited relative higher expression in males (collagen 3, matrix metalloproteinase 2, TIMP2, and TGFβ2, all about twofold) after TAC. We confirmed 87% of the gene expression by real-time polymerase chain reaction. By GO classification, female-specific genes were related to mitochondria and metabolism and males to matrix and biosynthesis. Promoter studies confirmed the upregulation of PGC-1 by E2. Less downregulation of metabolic genes in female hearts and increased protein synthesis capacity and deregulation of matrix remodeling in male hearts characterize the sex-specific early response to PO. These differences could contribute to subsequent sex differences in cardiac function and HF