Dysregulated autophagy may lead to the development of disease. Role of autophagy and the diagnostic potential of microRNAs that regulate the autophagy in cardiac hypertrophy have not been evaluated. A rat model of cardiac hypertrophy was established using transverse abdominal aortic constriction (operation group). Cardiomyocyte autophagy was enhanced in rats from the operation group, compared with those in the sham operation group. Moreover, the operation group showed up-regulation of beclin-1 (an autophagy-related gene), and down-regulation of miR-30 in cardiac tissue. The effects of inhibition and over-expression of the beclin-1 gene on the expression of hypertrophy-related genes and on autophagy were assessed. Angiotensin II-induced myocardial hypertrophy was found to be mediated by over-expression of the beclin-1 gene. A dual luciferase reporter assay confirmed that beclin-1 was a target gene of miR-30a. miR-30a induced alterations in beclin-1 gene expression and autophagy in cardiomyocytes. Treatment of cardiomyocytes with miR-30a mimic attenuated the Angiotensin II-induced up-regulation of hypertrophy-related genes and decreased in the cardiomyocyte surface area. Conversely, treatment with miR-30a inhibitor enhanced the up-regulation of hypertrophy-related genes and increased the surface area of cardiomyocytes induced by Angiotensin II. In addition, circulating miR-30 was elevated in patients with left ventricular hypertrophy, and circulating miR-30 was positively associated with left ventricular wall thickness. Collectively, these above-mentioned results suggest that Angiotensin II induces down-regulation of miR-30 in cardiomyocytes, which in turn promotes myocardial hypertrophy through excessive autophagy. Circulating miR-30 may be an important marker for the diagnosis of left ventricular hypertrophy.
Cardiac hypertrophy is characterized by thickening myocardium and decreasing in heart chamber volume in response to mechanical or pathological stress, but the underlying molecular mechanisms remain to be defined. This study investigated altered miRNA expression and autophagic activity in pathogenesis of cardiac hypertrophy. A rat model of myocardial hypertrophy was used and confirmed by heart morphology, induction of cardiomyocyte autophagy, altered expression of autophagy-related ATG9A, LC3 II/I and p62 proteins, and decrease in miR-34a expression. The in vitro data showed that in hypertrophic cardiomyocytes induced by Ang II, miR-34a expression was downregulated, whereas ATG9A expression was up-regulated. Moreover, miR-34a was able to bind to ATG9A 3′-UTR, but not to the mutated 3′-UTR and inhibited ATG9A protein expression and autophagic activity. The latter was evaluated by autophagy-related LC3 II/I and p62 levels, TEM, and flow cytometry in rat cardiomyocytes. In addition, ATG9A expression induced either by treatment of rat cardiomyocytes with Ang II or ATG9A cDNA transfection upregulated autophagic activity and cardiomyocyte hypertrophy in both morphology and expression of hypertrophy-related genes (i.e., ANP and β-MHC), whereas knockdown of ATG9A expression downregulated autophagic activity and cardiomyocyte hypertrophy. However, miR-34a antagonized Ang II-stimulated myocardial hypertrophy, whereas inhibition of miR-34a expression aggravated Ang II-stimulated myocardial hypertrophy (such as cardiomyocyte hypertrophy-related ANP and β-MHC expression and cardiomyocyte morphology). This study indicates that miR-34a plays a role in regulation of Ang II-induced cardiomyocyte hypertrophy by inhibition of ATG9A expression and autophagic activity.
MicroRNA (miR)-26 was found to be downregulated in cardiac diseases. In this study, the critical role of miR-26 in myocardial hypertrophy in both in vivo and in vitro was investigated. Sixteen male Wistar rats that underwent sham or transverse abdominal aortic constriction (TAAC) surgery were divided into control or TAAC group. Cardiomyocytes were isolated from neonatal Sprague-Dawley rats. Our study demonstrated that miR-26a/b was downregulated in both TAAC rat model and cardiomyocytes. The results of luciferase assays also suggested that glycogen synthase kinase 3β (GSK3β) may be a direct target of miR-26. The overexpression of miR-26 attenuated GSK3β expression and inhibited myocardial hypertrophy. The downregulation of miR-26 reversed these effects. Furthermore, silence of GSK3β gene phenocopied the anti-hypertrophy effects of miR-26, whereas overexpression of this protein attenuated the effects of miR-26. Taken together, these data suggest that miR-26 regulates pathological structural changes in the rat heart, which may be associated with suppression of the GSK3β signaling pathway, and implicate the potential application of miR-26 in diagnosis and therapy of cardiac hypertrophy.
Cervical cancer is strongly associated with the infection by oncogenic forms of human papillomavirus (HPV). Although most women are able to clear HPV infection, some develop persistent infections that may lead to cancer, implying genetic susceptibility factors for malignant progression. To verify whether HLA class II DQB1 polymorphism is related to cervical cancer in Chinese population, HLA-DQB typing was carried out by PCR-SBT for 258 patients with cervical cancer and 284 healthy controls, and the allele frequencies were calculated. In this study, HLA-DQB1*060101 and DQB1*0602 alleles were significantly higher in the HPV16 infected patients with cervical cancer compared with healthy controls (v 2 5 31.7452, p < 0.0001; v 2 5 12.7838, p c 5 0.0066), but DQB1*050201 allele was significantly lower (v 2 5 26.2187, p < 0.0001). This result indicates that HLA-DQB1*060101 and DQB1*0602 may confer susceptibility to cervical cancer, and DQB1*050201 may contribute to the resistance to the development of cervical cancer among Chinese women. Sequence analysis reveals that DQB1*060101 allele encodes Leu at position 9 and Asp at position 37, unique to the susceptibility to cervical cancer, whereas the other DQB1 alleles encode Phe or Tyr and Ile or Tyr at the same two positions, respectively. This finding implies that polymorphic amino acids at the putative antigen binding residues 9 and 37 of HLA-DQB1 alleles may play an important role in the development of cervical cancer. ' 2006 Wiley-Liss, Inc.Key words: cervical cancer; HLA; polymorphism; human papillomavirus; susceptibility Cervical cancer is the second most common cancer in women, accounting for 9.8% of all new cancer cases worldwide (371,200 new cases per year), with a disproportionate share of the mortality associated with this disease occurring in developing countries. 1 Human papillomavirus (HPV) is the major etiologic factor in cervical cancer and is found in the majority of cervical tumors. 2 Infections are common but only a small fraction progresses into persistent infection and cancer, suggesting that other factors are needed for the pathogenesis. 3 One potential cofactor may be the host cellular immune response to HPV infection, mediated by HLA-restricted T lymphocytes. To date, there are more than 100 different HPV genotypes. There are 40 known genital HPVs, which are further divided into high-risk (oncogenic: 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73, 82, et al.) and low risk (e.g. 6, 11, 40, 42, 43, 44, 54, 61, 70, 72, 81, et al.) types. 4,5 HPV 16 is the most common type associated with cervical cancer worldwide, with little geographic variation. 6 Naturally occurring HPV-16 variants differ in certain biologic properties and might result in differences in pathogenicity. However, previous studies showed that HPV16 E6 variants appeared to be correlated with distinct MHC class II haplotypes. 7,8 Engelmark et al. 9 reported that the HLA class II genes represented a major genetic susceptibility region to cervical cancer in contrary to the clas...
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