Is Prehypertension Really Different from Normotension and Hypertension? A Case-Control Pilot Proteomic Study in Chinese

Candesartan cilexetil attenuated cardiac remodeling by improving expression and function of mitofusin 2 in SHR

BACKGROUND

Left ventricular hypotrophy (LVH) is very common in hypertensives even after antihypertensive treatment. Mitofusin 2 (Mfn2) is a critical negative regulator of vascular smooth muscle cell (VSMC) hypertrophy by regulating mitochondrial fusion, ras/raf/MEK signal pathway, et al. The purpose of this study was to investigate whether candesartan attenuated cardiac remodeling by improving expression and function of mitofusin 2 in SHR.

METHODS

Nine weeks old spontaneously hypertensive rats (SHR) were selected and treated with candesartan for eight weeks. Then, heart tissues were investigated for signs of cardiac remodeling, mitochondrial structure and membrane potential, mitochondrial enzyme activities, hydrogen peroxide, mRNA and protein expression of Mfn2/ras/raf/MEK signaling pathway in heart tissues.

RESULTS

The results showed that cardiac remodeling was obviously in SHR group: cardiac cell alignment was irregular; cardiac fibers became thick, irregular and enlarged; cell density was reduced in SHR compared to WKY. After candesartan treatment, histopathological structure improved significantly which were consistent with mitochondrial morphology, mitochondrial membrane potential, mitochondrial enzyme activities, hydrogen peroxide, Mfn2/ras/raf/MEK gene and protein expression in cardiac tissues. What's more, although blood pressure was well controlled in a normal range, cardiac remodeling wasn't avoided. In general, candesartan obviously repressed cardiac hypertrophy and cardiac remodeling significantly compared to SHR untreated group, but didn't reverse it.

CONCLUSIONS

Mfn2 is negatively associated with cardiac remodeling. Candesartan treatment can improve mitochondrial structure and function and regulate Mfn2/ras/raf/MEK signaling pathway. Mfn2 may be used a potential marker for cardiac remodeling and a novel therapeutic target for target organ damage protection.

A novel 5'-uncoding region -1248 A>G variation of mitofusin-2 gene is associated with hypertension in Chinese

PURPOSE

Mitofusin2 gene (Mfn2, also named Hyperplasia suppressive gene, HSG) is very important in the origin and development of hypertension. However, the mechanism of Mfn2/HSG expression regulation was not uncovered. This study was designed to explore the association of a novel 5'-uncoding region (UCR) -1248 A>G variation of HSG/Mfn2 gene and hypertension.

MATERIALS AND METHODS

472 healthy, normotensive subjects [normotension (NT) group], 454 prehypertensive subjects [prehypertension (PH) group] and 978 hypertensive patients [essential hypertension (EH) group] were screened for an association study between 5'-UCR -1248 A>G of Mfn2/HSG and hypertension by polymerase chain reaction and DNA sequencing after venous blood was drawn and DNA was extracted.

RESULTS

When comparing the A and G frequency in EH, PH and NT groups, in total, NT group significantly had higher A frequency than in PH group [odds ratio (OR)=1.605, confidence interval (CI) 95%=1.063-2.242, p=0.025] and EH group (OR=5.395, CI 95%=3.783-7.695, p<0.01). When subgrouped by gender, A frequency in NT group was still significantly higher than in EH group (male: OR= 4.264, CI 95%=2.780-6.543, p<0.01; female: OR=8.897, CI 95%=4.686-16.891, p<0.01), but not from PH group, either in male group or in female group. Ordinal Logistic Regression analysis showed that A>G variation was significantly related with blood pressure level (B=-1.271, Wald=40.914, CI 95%=-1.660 - -0.881, p<0.01).

CONCLUSION

5'-UCR -1248 A>G variation of Mfn2/HSG gene was a novel variation and may be associated with hypertension in Chinese.

HSG/Mfn2 gene polymorphism and essential hypertension: a case-control association study in Chinese

AIM

Hyperplasia suppressor gene/mitofusion-2 (HSG/Mfn2) is a hyperplasia suppressor gene and an essential component of mitochondrial fusion machinery; however, the association between the single nucleotide polymorphism (SNP) of HSG/Mfn2 and hypertension is unclear.

METHODS

In this study, 542 normotensive subjects (NT group) and 539 hypertensive patients (EH group) were screened for an association study between HSG/Mfn2 and hypertension.

RESULTS

The results showed that the genotype distribution and allelic frequency of rs873457, rs2336384, rs1474868, rs4846085 and rs2236055 were significantly different (p lt; 0.05 for all) between EH and NT groups, although those of rs4240897 and rs873458 were not. When comparing the dominant model, significant differences still existed (p lt; 0.05 for all). The allelic frequency of rs4240897 was also slightly different between EH and NT groups (P = 0.047). When subgrouped by sex, the genotype distribution and allelic frequency of all the SNPs (except rs873458) were significantly different in male (p lt; 0.05 for all) but not in female groups. For all the SNPs, only the allelic frequency of rs4240897 was obviously different in female NT and EH groups (p lt; 0.01). Logistic regression showed that body mass index and rs873457 were closely associated with BP after adjusting for age. The frequency of the C-G-A-A-A-C-C haplotype was significantly higher in essential hypertensive patients versus control individuals, both in the entire population, in male or female groups (p lt; 0.01 for all). As for other haplotypes, most were only significantly different in the entire population and male subjects.

CONCLUSION

The genetic variations of HSG/Mfn2 may be associated with hypertension in male Chinese.

E-selectin gene polymorphisms are associated with essential hypertension: a case-control pilot study in a Chinese population

Background

Genetic variation is thought to contribute to the etiology of hypertension, and E-selectin is a candidate essential hypertension-associated gene. This study thus sought to investigate possible genetic associations between the T1880C, C602A and T1559C polymorphisms of E-selectin and essential hypertension.

Methods

Hypertensive patients (n = 490) and healthy normotensive subjects (n = 495) were screened for the genotypes T1880C, C602A and T1559C using real-time quantitative polymerase chain reaction after DNA extraction to identify representative variations in the E-selectin gene. The associations between genotypes and alleles of the three mutations and essential hypertension were then analyzed using a case-control study.

Results

Hypertensive patients and normotensive subjects were significantly different with respect to the genotypes CC, CA and AA (P = 0.005) and the C-allele frequency of C602A (P = 0.001). A comparison of dominant versus recessive models also revealed significant differences between the two groups (P = 0.004 and P = 0.02). When subgrouped by gender, these indexes differed significantly between normotensive and essential hypertensive males, but not in females. The additive model of the T1559C genotype did not differ between essential hypertensive and normotensive groups overall (P = 0.39), but it was different between hypertensive and normotensive males (P = 0.046) and females (P = 0.045). The CC + TC versus TT frequency of T1559C was also different in the recessive model of male hypertensive and normotensive groups (P = 0.02). Further analysis showed that C602A and T1559C were significantly associated with hypertension (C602A: OR = 7.58, 95%CI = 1.53-11.97, P < 0.01; and T1559C: OR = 6.77, 95%CI = 1.07-1.83, P < 0.05). The frequency of the C-C-C haplotype was significantly higher in hypertensive patients than in control individuals as well as in hypertensive and normotensive males (P = 0.008 and 0.01). The frequency of the C-A-T haplotype was higher only in male hypertensives and normotensives (P = 0.015). Furthermore, there was a significant interaction between E-selectin and gender (P = 0.02 for C602A and 0.04 for T1559C).

Conclusion

C602A and T1559C may be independent risk factors for essential hypertension in the Chinese population, whereas T1880C is not.