Changes in microRNAs expression are involved in age-related atrial structural remodeling and atrial fibrillation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Small noncoding microRNAs regulate gene expression in cardiac development and disease and have been implicated in the aging process and in the regulation of extracellular matrix proteins. However, their role in age-related cardiac remodeling and atrial fibrillation (AF) was not well understood. The present study was designed to decipher molecular mechanisms underlying age-related atrial structural remodeling and AF.</p><p><b>METHODS</b>Three groups of dogs were studied: adult and aged dogs in sinus rhythm and with persistent AF induced by rapid atrial pacing. The expressions of microRNAs were measured by quantitative real-time polymerase chain reaction. Pathohistological and ultrastructural changes were tested by light and electron microscopy. Apoptosis index of myocytes was detected by TUNEL.</p><p><b>RESULTS</b>Samples of atrial tissue showed the abnormal pathohistological and ultrastructural changes, the accelerated fibrosis, and apoptosis with aging and/or in AF dogs. Compared to the adult group, the expressions of microRNAs-21 and -29 were significantly increased, whereas the expressions of microRNAs-1 and -133 showed obvious downregulation tendency in the aged group. Compared to the aged group, the expressions of microRNAs-1, -21, and -29 was significantly increased in the old group in AF; contrastingly, the expressions of microRNA-133 showed obvious downregulation tendency.</p><p><b>CONCLUSION</b>These multiple aberrantly expressed microRNAs may be responsible for modulating the transition from adaptation to pathological atrial remodeling with aging and/or in AF.</p>

Association of single nucleotide polymorphism of KCNE1 and KCNE4 gene with atrial fibrillation in Xinjiang Uygur and Han population / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the association between the KCNE1 gene G38S and the KCNE4 gene E145D and atrial fibrillation in Uygur and Han populations living in Xinjiang.</p><p><b>METHODS</b>KCNE1 gene G38S and the KCNE4 gene E145D genotype and frequency were determined using PCR restriction fragment length polymorphism (PCR-RFLP) in 488 atrial fibrillation patients (237 Uygur and 251 Han residents) and 488 age-and-gender matched controls (237 Uygur and 251 Han residents).</p><p><b>RESULTS</b>Genotype and allele frequency of KCNE1 gene G38S were similar between atrial fibrillation group and control group in the Han population (P = 0.556, P = 0.946). In the Uygur population, there was a statistical difference between atrial fibrillation group and control group (P = 0.018, P = 0.003). Logistic regression analysis revealed the KCNE1 38 G was one of the independent risk factors for atrial fibrillation in the Uygur population (OR = 1.634, 95%CI: 1.192-2.240, P = 0.002). The KCNE4 gene E145D, genotype and allele frequency were significantly different between atrial fibrillation group and control group in the Uygur population and Han population (P = 0.041, P = 0.015;P = 0.032, P = 0.013) . Logistic regression analysis revealed the KCNE4 145D was one of the independent risk factors for atrial fibrillation in the Uygur population and Han population (OR = 1.636, 95%CI:1.173-2.281, P = 0.004; OR = 1.491, 95%CI:1.076-2.065, P = 0.016) .</p><p><b>CONCLUSIONS</b>KCNE1 G38S is not associated with atrial fibrillation in the Han population while the KCNE1 G38S is associated with atrial fibrillation in the Uygur population. KCNE4 gene E145D is associated with atrial fibrillation in both Uygur population and Han population.</p>

Aging-related ionic remodeling of L-type voltage dependent calcium channel in left atria of canine / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate aging-related ionic remodeling of L-type voltage dependent calcium channel (LVDCC) in left atria of canine.</p><p><b>METHODS</b>Seven adult (2.0 - 2.5 years) and 10 aged (> 8 years) dogs were used. The current of LVDCC was recorded by patch clamp technique in the whole cell mode. The action potential duration (APD(90)), amplitude of action potential plateau (APA), I(Ca-L) peak current density of LVDCC were recorded. The mRNA and protein expressions of α1c subunit (Ca(V1.2)), sarcoplasmic reticulum Ca(2+)-ATPase (SECRA(2)), Calpain-I, ryanodine receptor (RYR(2)) were detected by quantitative RT-PCR and Western blot, respectively.</p><p><b>RESULTS</b>I(Ca-L) peak current density [(-8.11 ± 0.54) pA/pF vs. (-14.04 ± 0.82) pA/pF, P < 0.05] was significantly reduced and action potential duration to 90% repolarization (APD(90)) significantly prolonged [(340.5 ± 10.1) ms vs. (320.0 ± 7.9) ms, P < 0.05] in aged group than in adult group. The mRNA gene expression level of Ca(V1.2) was significantly lower (0.90 ± 0.35 vs. 2.38 ± 0.40, P < 0.05) while mRNA expression of RYR(2) was significantly higher (4.39 ± 4.68 vs. 1.49 ± 1.69, P < 0.05) in the aged dogs than in the adult dogs. mRNA expression of SECRA(2) and Calpain-I was similar between the two groups. Similarly, the protein expression level of Ca(V1.2) was significantly lower (0.13 ± 0.10 vs. 0.29 ± 0.12, P < 0.05) while the protein expression level of RYR(2) was significantly higher (0.18 ± 0.21 vs. 0.08 ± 0.36, P < 0.05) in the aged dogs than in the adult dogs. Again, protein expression of SECRA(2), PLN(1) and Calpain-I was similar between the two groups.</p><p><b>CONCLUSION</b>These data suggest that aging could induce mRNA and protein expression changes of Ca(V1.2) and RYR(2) of LVDCC which might serve as the molecular basis of I(Ca-L) remodeling in aged dogs and might be linked to the increased likelihood of developing atrial fibrillation (AF) in aged dogs.</p>

Differential expression of collagen and matrix metalloproteinases between left and right atria in patients with chronic atrial fibrillation / 生理学报

The present study aimed to investigate the mRNA expression levels of collagen, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) in the left and right atria in patients with chronic atrial fibrillation (CAF). Forty five patients with valvular heart disease were sampled in this study, including 18 patients with sinus rhythm (SR), 27 patients with CAF. Clinical data of these patients were collected, and the left and right atrial appendages were obtained from these patients during heart valvular replacement surgery. The mRNA levels of collagen type I, collagen type III, MMP1, MMP9, TMP1 of the atria were then measured by semi-quantitative RT-PCR. The results obtained were as follows. Compared to those in SR group, in atria of CAF group, the mRNA levels of collagen type I, MMP1 and MMP9 increased (P<0.05), while the mRNA level of TMP1 decreased (P<0.01). There were no significant differences in the mRNA levels of collagen type I, collagen type III, MMP1, MMP9 and TMP1 between the left and right atria of SR group (P>0.05). In CAF group, the mRNA level of MMP1 in the right atrium was higher than that in the left atrium (P<0.05), however, the mRNA level of MMP9 in the left atrium was higher than that in the right atrium (P<0.01). In both the left and right atria, the mRNA of collagen type I was positively correlated with the corresponding atrial diameter; the mRNA of MMP1 and MMP9 was positively correlated with the mRNA of collagen type I, and was negatively correlated with the mRNA of TMP1. These results suggest that the increased level of collagen type I associated with selective upregulation of MMP1, 9 and downregulation of TMP1, 9 in the atrium might be the molecular basis of atrial interstitial fibrosis in patients with CAF. Moreover, during CAF development, there is difference in the expression of MMPs between the left and right atria.