Ruizhe Qian

MicroRNA-320 EXPRESSION IN MYOCARDIAL MICROVASCULAR ENDOTHELIAL CELLS AND ITS RELATIONSHIP WITH INSULIN-LIKE GROWTH FACTOR-1 IN TYPE 2 DIABETIC RATS

1 The aim of the present study was to determine the role of myocardial microvascular endothelial cells (MMVEC) in impaired angiogenesis of type 2 diabetic Goto‐Kakizaki (GK) rats. 2 A microRNA (miRNA) microarray was used to assess miRNA expression in MMVEC from GK and Wistar rats. Upregulation of miRNA‐320 was observed in MMVEC from GK rats using real‐time reverse transcription–polymerase chain reaction (RT‐PCR). 3 So far, nine miRNAs have been reported to target angiogenic factors and/or receptors, including kinase insert domain containing receptor (Flk‐1), insulin‐like growth factor 1 (IGF‐1) and insulin‐like growth factor 1 receptor (IGF‐1R). The predicted genes targeted by miR‐320 include Flk‐1, IGF‐1 and IGF‐1R. Western blot analysis and RT‐PCR were used to analyse the protein and mRNA expression, respectively, of the putative genes IGF‐1 and IGF‐1R. The expression of IGF‐1 and IGF‐1R proteins decreased significantly in diabetic MMVEC. However, the expression of IGF‐1 mRNA increased rather than decreased. The mRNA expression of IGF‐1R did not differ significantly between diabetic and control MMVEC. 4 Transfection of an miR‐320 inhibitor into MMVEC from GK rats confirmed that miR‐320 impaired angiogenesis. The proliferation and migration of diabetic MMVEC improved after transfection of the miR‐320 inhibitor. In addition, the miR‐320 inhibitor significantly increased the expression of IGF‐1 protein, but had no effect on the expression of IGF‐1R. 5 Eleven miRNAs were upregulated in MMVEC from GK rats compared with those in Wistar rats: let‐7e, miR‐129, miR‐291‐5p, miR‐320, miR‐327, mir‐333, miR‐363–5p, miR‐370, miR‐494, miR‐503 and miR‐664. 6 The results indicate that upregulation of miR‐320 in MMVEC from GK rats may be responsible for the inconsistency between the expression of IGF‐1 protein and mRNA and therefore related to impaired angiogenesis in diabetes. Transfection of an miR‐320 inhibitor may be a therapeutic approach for the treatment of impaired angiogenesis in diabetes.

Bach1 Represses Wnt/β-Catenin Signaling and Angiogenesis

RATIONALE Wnt/β-catenin signaling has an important role in the angiogenic activity of endothelial cells (ECs). Bach1 is a transcription factor and is expressed in ECs, but whether Bach1 regulates angiogenesis is unknown. OBJECTIVE This study evaluated the role of Bach1 in angiogenesis and Wnt/β-catenin signaling. METHODS AND RESULTS Hind-limb ischemia was surgically induced in Bach1(-/-) mice and their wild-type littermates and in C57BL/6J mice treated with adenoviruses coding for Bach1 or GFP. Lack of Bach1 expression was associated with significant increases in perfusion and vascular density and in the expression of proangiogenic cytokines in the ischemic hindlimb of mice, with enhancement of the angiogenic activity of ECs (eg, tube formation, migration, and proliferation). Bach1 overexpression impaired angiogenesis in mice with hind-limb ischemia and inhibited Wnt3a-stimulated angiogenic response and the expression of Wnt/β-catenin target genes, such as interleukin-8 and vascular endothelial growth factor, in human umbilical vein ECs. Interleukin-8 and vascular endothelial growth factor were responsible for the antiangiogenic response of Bach1. Immunoprecipitation and GST pull-down assessments indicated that Bach1 binds directly to TCF4 and reduces the interaction of β-catenin with TCF4. Bach1 overexpression reduces the interaction between p300/CBP and β-catenin, as well as β-catenin acetylation, and chromatin immunoprecipitation experiments confirmed that Bach1 occupies the TCF4-binding site of the interleukin-8 promoter and recruits histone deacetylase 1 to the interleukin-8 promoter in human umbilical vein ECs. CONCLUSIONS Bach1 suppresses angiogenesis after ischemic injury and impairs Wnt/β-catenin signaling by disrupting the interaction between β-catenin and TCF4 and by recruiting histone deacetylase 1 to the promoter of TCF4-targeted genes.

The rhythmic expression of clock genes attenuated in human plaque-derived vascular smooth muscle cells

BackgroundAcute myocardial infarction and stroke are more likely to occur in the early morning. Circadian pacemakers are considered to be involved in the process. Many peripheral tissues and cells also contain clock systems. In this study, we examined whether the primary cultured human plaque-derived vascular smooth muscle cells (VSMCs) process circadian rhythmicity; furthermore, we investigated the expression difference of clock genes between normal human carotid VSMCs and human plaque-derived VSMCs.MethodsFifty-six human carotid plaques provided the atherosclerotic tissue, and 21 samples yielded viable cultured primary VSMCs. The normal carotid VSMCs were cultured from donors’ normal carotids. The mRNA levels of the target genes were measured by Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR).ResultsAfter serum shock, both types of cells showed clear circadian expressions of Bmal1, Cry1, Cry2, Per1, Per2, Per3 and Rev-erbα mRNA; meanwhile the Clock mRNA show a rhythmic expression in plaque-derived SMCs but not in normal carotid VSMCs. The expression levels of these main clock genes were significantly attenuated in human plaque-derived VSMCs compared with normal human carotid VSMCs. The rhythm of Bmal1 mRNA in plaque-derived VSMCs was changed.ConclusionThe present results demonstrate that the human plaque-derived VSMCs possess different circadian rhythmicity from that of normal carotid VSMCs. The rhythm changes of clock genes in plaque-derived VSMCs may be involved in the process of atherosclerosis and finally promote the rupture of plaque.

Rhythm changes of clock genes, apoptosis-related genes and atherosclerosis-related genes in apolipoprotein E knockout mice

BACKGROUND Acute myocardial infarction and stroke occur more frequently in the morning, suggesting a role of the circadian clock in these main causes of death, secondary to atherosclerosis. OBJECTIVES To investigate the expression of clock genes, apoptosis-related genes and atherosclerosis-related genes in the process of atherosclerosis. METHODS Apolipoprotein E knockout (ApoE-/-) mice were used to establish animal models of early and advanced atherosclerosis. Real-time polymerase chain reaction, Western blotting and microarray assays were used to detect the expression of clock genes, apoptosis-related genes and atherosclerosis-related genes. RESULTS Clock genes in ApoE-/- and C57BL/6J mouse hearts exhibited daily oscillations at the messenger RNA level. However, the expression level and rhythm between ApoE-/- and C57BL/6J mice were significantly different. Moreover, the changes became more significant as atherosclerosis developed. c-Myc and p53 genes exhibited circadian expression in C57BL/6J mice at messenger RNA and protein levels. However, the rhythm in ApoE-/- mice disappeared completely. Bcl-2 and Bax did not show daily rhythm in either strain of mouse. Aside from apoptosis-related genes, several atherosclerosis-related genes expressed time-dependent behaviour in C57BL/6J mice but not in ApoE-/- mice. CONCLUSIONS Rhythm changes of clock genes, apoptosis-related genes and atherosclerosis-related genes may play important roles in atherosclerosis and its complications.

Postnatal ontogenesis of clock genes in mouse suprachiasmatic nucleus and heart

BackgroundThe master clock within the hypothalamic suprachiasmatic nucleus (SCN) synchronizing clocks in peripheral tissues is entrained by the environmental condition, such as the light-dark (LD) cycle. The mechanisms of circadian clockwork are similar in both SCN and peripheral tissues. The aim of the present work was to observe the profiles of clock genes expression in mouse central and peripheral tissues within postnatal day 5 (P5). The daily expression of four clock genes mRNA (Bmal1, Per2, Cry1 and Rev-erb alpha) in mouse SCN and heart was measured at P1, P3 and P5 by real-time PCR.ResultsAll the studied mice clock genes began to express in a circadian rhythms manner in heart and SCN at P3 and P5 respectively. Interestingly, the daily rhythmic phase of some clock genes shifted during the postnatal days. Moreover, the expressions of clock genes in heart were not synchronized with those in SCN until at P5.ConclusionThe data showed the gradual development of clock genes in SCN and a peripheral tissue, and suggested that development of clock genes differed between in the SCN and the heart. Judging from the mRNA expression, it was possible that the central clock synchronized the peripheral clock as early as P5.

Effects of high glucose plus high insulin on proliferation and apoptosis of mouse endothelial progenitor cells

Abstract.Objective:To study the effects of high glucose plus high insulin (GI) on proliferation, apoptosis, morphology and differentiation of endothelial progenitor cells (EPC).Methods:EPC were isolated and identified by magnetic cell sorting and flow cytometry. EPC proliferation and apoptosis were measured by MTT assay and Annexin-V/PI double labeling, respectively. Cell proliferation- and apoptosis-related factors were examined by Western blotting.Results:Seven days after GI treatment, EPC were arrested at the G0/G1 phase. Treatment with high glucose alone (HG) or GI but not HI (high insulin alone) decreased EPC proliferation and their expression of cyclin E, cdk2 and PCNA compared to control. The inhibitory effects of HG on EPC proliferation and growth-related proteins were more significant than those of GI. HG, GI and HI promoted EPC apoptosis along with caspase-3 overexpression.Conclusion:The result indicated that GI-induced apoptosis and growth inhibition might be one of mechanisms of EPC reduction and dysfunction in diabetes.

Effect of H2S on the circadian rhythm of mouse hepatocytes

BackgroundDysregulation of circadian rhythms can contribute to diseases of lipid metabolism. NAD-dependent deacetylase sirtuin-1(SIRT1) is an important hub which links lipid metabolism with circadian clock by its deacetylation activity depends on intracellular NAD+/NADH content ratio. Hydrogen sulfide (H2S) is an endogenous reductant which can affect the intracellular redox state. Therefore, we hypothesized that exogenous H2S can affect the expression of circadian clock genes mediated by sirt1 thereby affecting bodys lipid metabolism. And also because the liver is a typical peripheral circadian clock oscillator that is intimately linked to lipid metabolism. Thus the effect of H2S were observed on 24-hour dynamic expression of 4 central circadian clock genes and sirt1gene in primary cultured hepatocytes.ResultsWe established a hepatocyte model that showed a circadian rhythm by serum shock method. And detected that the expression level and the peak of circadian clock genes decreased gradually and H2S could maintain the expression and amplitude of circadian clock genes such as Clock, Per2, Bmal1 and Rev-erbαwithin a certain period time. Accordingly the expression level of sirt1 in H2S group was significantly higher than that in the control group.ConclusionExogenous reductant H2S maintain the circadian rhythm of clock gene in isolated liver cells. We speculated that H2S has changed NAD+/NADH content ratio in hepatocytes and enhanced the activity of SIRT1 protein directly or indirectly, so as to maintain the rhythm of expression of circadian clock genes, they play a role in the prevention and treatment of lipid metabolism-related disease caused by the biological clock disorders.

Effect of hyperlipidemia on the expression of circadian genes in apolipoprotein E knock-out atherosclerotic mice

BackgroundCircadian patterns of cardiovascular vulnerability were well characterized, with a peak incidence of acute myocardial infarction and stroke secondary to atherosclerosis in the morning, which showed the circadian clock may take part in the pathological process of atherosclerosis induced by hyperlipidemia. Hence, the effect of hyperlipidemia on the expression of circadian genes was investigated in atherosclerotic mouse model.ResultsIn apoE-/-mice on regular chow or high-fat diet, an atherosclerotic mouse model induced by heperlipidemia, we found that the peak concentration of serum lipids was showed four or eight hours later in apoE-/- mice, compared to C57BL/6J mice. During the artificial light period, a reduce in circulating level of serum lipids corresponded with the observed increase of the expression levels of some the transcription factors involved in lipid metabolism, such as PPARα and RXRα. Meanwhile, the expression of circadian genes was changed following with amplitude reduced or the peak mRNA level delayed.ConclusionsOur studies indicated that heperlipidemia altered both the rhythmicity and expression of circadian genes. Diet-induced circadian disruption may affect the process of atherosclerosis and some acute cardiovascular disease.

Circadian gene hClock enhances proliferation and inhibits apoptosis of human colorectal carcinoma cells in vitro and in vivo

Colorectal carcinoma (CRC) is one of the most prevalent types of malignancy-associated mortality worldwide. Previous studies have demonstrated that amplification and overexpression of the human circadian locomotor output cycles kaput gene (hClock) was closely associated with a high risk for CRC as well as poor prognosis in CRC patients. However, the underlying molecular mechanisms of CRC remain to be fully elucidated. In the present study, hClock was exogenously overexpressed in the CRC cell line SW480 via infection of a lentivirus vector expressing hClock; in addition, a lentivirus vector-based RNA interference approach, using short hairpin RNA, was performed in order to knockdown hClock in SW620 cells. The results showed that upregulation of hClock promoted proliferation and inhibited apoptosis in SW480 cells in vitro and in vivo, while downregulation of hClock inhibited SW620 cell proliferation and accelerated apoptosis in vitro. Upregulation of hClock enhanced the activity of the anti-apoptotic gene phosphorpylated (p-) AKT and inhibited the expression of the pro-apoptotic gene B cell lymphoma-2 (Bcl-2)-associated X protein and Bcl-2 homology 3 interacting domain death agonist. Furthermore, targeted inhibition of hClock activity reduced p-AKT expression. In conclusion, the results of the present study suggested that the circadian gene hClock promoted CRC progression and inhibit tumor cell apoptosis in vitro and in vivo, while silencing hClock was able to reverse this effect.

CLOCK promotes 3T3‐L1 cell proliferation via Wnt signaling

Circadian genes control most of the physiological functions including cell cycle. Cell proliferation is a critical factor in the differentiation of progenitor cells. However, the role of Clock gene in the regulation of cell cycle via wingless‐type (Wnt) pathway and the relationship between Clock and adipogenesis are unclear. We found that the circadian locomotor output cycles kaput (Clock) regulated the proliferation and the adipogenesis of 3T3‐L1 preadipocytes. We found that Clock attenuation inhibited the viability of 3T3‐L1 preadipocytes in the cell counting kit 8. The expression of c‐Myc and Cyclin D1 decreased dramatically in 3T3‐L1 when Clock was silenced with short interfering RNA and was also decreased in fat tissue and adipose tissue‐derived stem cells of ClockΔ19 mice. Clock directly controls the expression of the components of Wnt signal transduction pathway, which was verified by serum shock, chromatin immunoprecipitation, Western blot, and quantitative real‐time polymerase chain reaction (qRT‐PCR). Furthermore, IWR‐1, a Wnt signal pathway inhibitor, inhibited the cell cycle promotion by CLOCK, which was detected by cell viability assay, flow cytometry, and qRT‐PCR. Therefore, CLOCK transcription control of Wnt signaling promotes cell cycle progression in 3T3‐L1 preadipocytes. Clock inhibited the adipogenesis on day 2 in 3T3‐L1 cells via Oil Red O staining and qRT‐PCR detection and probably related to cellular differentiation. These data provide evidence that the circadian gene Clock regulates the proliferation of preadipocytes and affects adipogenesis.