Significant roles of anti-aging protein klotho and fibroblast growth factor23 in cardiovascular disease.

The klotho gene has been identified as an aging suppressor that encodes a protein involved in cardiovascular disease (CVD). The inactivation of the klotho gene causes serious systemic disorders resembling human aging, such as atherosclerosis, diffuse vascular calcification and shortened life span. Klotho has been demonstrated to ameliorate vascular endothelial dysfunction and delay vascular calcification. Furthermore, klotho gene polymorphisms in the human are associated with various cardiovascular events. Recent experiments show that klotho may reduce transient receptor potential canonical6 (TRPC6) channels, resulting in protecting the heart from hypertrophy and systolic dysfunction. Fibroblast growth factor23 (FGF23) is a bone-derived hormone that plays an important role in the regulation of phosphate and vitamin D metabolism. FGF23 accelerates urinary phosphate excretion and suppresses 1,25-dihydroxy vitaminD3 (1,25(OH)2D3) synthesis in the presence of FGF receptor1 (FGFR1) and its co-receptor klotho, principally in the kidney. The hormonal affects of circulating klotho protein and FGF23 on vascular and heart have contributed to an understanding of their roles in the pathophysiology of arterial stiffness and left ventricular hypertrophy. Klotho and FGF23 appear to play a critical role in the pathogenesis of vascular disease, and may represent a novel potential therapeutic strategy for clinical intervention.

[Klotho gene attenuates the progression of hypertension and heart damage in spontaneous hypertensive rats].

OBJECTIVE: To assess the effect of Klotho gene transduction on the progression of hypertension and heart damage in spontaneous hypertensive rats (SHRs). METHODS: An adeno-associated virus (AAV) carrying full-length mouse Klotho cDNA (rAAV.mKL) was constructed for in vivo expression of Klotho. Three different groups of male SHRs and a control group of sex and age-matched Sprague Dawley (SD) rats (5 rats per group) were used. The experimental groups of SHRs received an IV injection of phosphate buffered saline (PBS), rAAV.mKL and rAAV.EGFP, respectively. The control group only received equal-volume of PBS. The whole study has spanned 12 weeks. Plasma levels of insulin-like growth factor-1 (IGF-1) and insulin were measured with ELISA. The weight of whole heart was measured to calculate the heart weight index (HWI). EGFP expression of heart frozen sections was observed by fluorescence microscopy. Expression of mRNA and protein of Klotho, IGF-1, IGF-1 receptor (IGF-1R) and p-Akt were determined with RT-PCR, immunohistochemical analysis, and Western blotting. Hypertrophic myocardial cell and collagen fiber were observed by histological examination following Haematoxylin-Eosin and Masson staining. RESULTS: Transduction of rAAV.mKL can significantly prevent the increase of blood pressure in SHRs. Compared with the control group, the levels of Klotho mRNA and protein have both increased, and the plasma levels of IGF-1, insulin and glucose were elevated, whereas the expression of phosphor-Akt (also called Protein Kinase B, PKB) was decreased in the rAAV.mKL group. Furthermore, a decrease of hypertrophic myocardial cells and collagen fibers was noticed in the rAAV.mKL group compared with the control group. CONCLUSION: The Klotho gene can attenuate the progression of hypertension and abolishes myocardial hypertrophy and myocardial fibrosis. The protective effect observed in the rAAV.mKL group of SHRs may be attributed to increased Klotho protein and suppression of insulin and IGF-1 signaling pathways through inhibition of Akt phosphorylation.

[The relationship between resting heart rate and single nucleotide polymorphism at 3 sites of nitric oxide synthase gene in the Chinese Han nationality population].

OBJECTIVE: To study the relationship between resting heart rate and single nucleotide polymorphisms (SNP) at 3 sites of nitric oxide synthase (NOS) gene including NOS3 -922A/G, NOS3 894G/T and NOS2 -1173C/T SNPs. METHODS: Genomic DNA was gained from 211 Chinese Han nationality population. The SNPs of NOS3 -922A/G, NOS3 894G/T and NOS2 -1173C/T were genotyped by allele-specific primer-polymerase chain reaction (ASP-PCR) technique. RESULTS: The distribution frequencies of GG, GT and TT genotypes of NOS3 894G/T and AA, AG and GG genotypes of NOS3 -922A/G and CC, CT and TT genotypes of NOS2 -1173C/T were consistent with Hardy-Weinberg equilibrium (P> 0.05). The resting heart rate of Chinese Han nationality population with AA genotypes was higher than that with GG genotype of NOS3 -922A/G (P< 0.01). The resting heart rate of the sub-population with GG genotype was higher than that with TT genotype of NOS3 894G/T (P< 0.05). There were no difference among the resting heart rates of the sub-populations with the allele genotypes of NOS2 -1173C/T. CONCLUSION: The resting heart rate of Chinese Han nationality population with mutated genotype GG of NOS3 -922A/G and with mutated genotype TT of NOS3 894G/T were lower than those with wild genotype of NOS3 -922A/G and NOS3 894G/T. The finding suggests that resting heart rate is associated with SNP of NOS3 -922A/G and NOS3 894G/T.

[Single nucleotide polymorphisms in NOS3 A-922G, T-786C and G894T: a correlation study of the distribution of their allelic combinations with hypertension in chinese Han population].

To study single nucleotide polymorphisms (SNP) in A-922G, T-786C and G894T of endothelial nitric oxide synthase (NOS3) and to correlate the distribution of their allelic combinations with hypertension in Chinese Han nationality population, genomic DNA was isolated from venous blood leukocytes from 192 unrelated patients with hypertension (95 females and 97 males) and 122 healthy unrelated individuals (46 females and 76 males) as controls. SNPs of NOS3 A-922G, T-786C and G894T were genotyped by allele-specific primer (ASP) PCR. The distribution of genotype combinations of three SNPs was determined by clustering analysis. There were no difference in allele genotype distribution frequency and haplotype frequency of NOS3 G894T, NOS3 A-922G and NOS3 T-786C between the essential hypertension group and the healthy population (P>0.05). According to sex stratification, no association between essential hypertension and SNP of NOS3 A-922G,NOS3 T-786C or NOS3 G894T has been found in either the male subgroup or the female subgroup. In respect of allele genotype combination frequency in the natural distribution of NOS3 A-922 G, NOS3 T-786C and NOS3 G894T SNP, there was significant difference only in the allele genotype combination frequency of NOS3 G894G+A-922G+T-786T between the hypertension group and the healthy group (P<0.05, Chi2=4.5944). According to sex stratification, there were no significant difference in all above allele genotype combination frequency in three sites of NOS3 SNP between the hypertension male subgroup and the healthy male subgroup (P>0.05). There was significant difference in the allele combination frequency of NOS3 G894G +A-922G+T-786C between the hypertension female subgroup and the healthy female subgroup(P<001, Chi2=8.502). There was no association of SNP in NOS3 A-922G, NOS3 T-786C or NOS3 G894T with hypertension in the Chinese Han nationality population, nor was there a sex difference. The combination frequency of allele NOS3 G894G + A-922G + T-786C in the hypertension female subgroup was much lower than that in the healthy female subgroup, suggesting that female population with this combination genotype may be less susceptible to hypertension.