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Biological clock proteins are involved in the regulation of many important physiological processes, including blood pressure. The deletion or mutation of core circadian clock genes may cause elevated blood pressure levels and disrupted blood pressure rhythms, exacerbating vascular function damage, and ultimately leading to the occurrence, development and poor outcome of ischemic stroke. This article reviews the molecular mechanism of biological clock rhythm, the relationship between biological clock gene and blood pressure regulation mechanism, the mechanism of circadian rhythm disorder in the occurrence and development of hypertension, and the relationship between blood pressure rhythm disorder and stroke.
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ObjectiveTo investigate the effect of Anmeidan （AMD） on biological rhythm and related protein expression in sleep-deprived rats. MethodA total of 80 SD rats were randomized into control group （Ctrl， equivalent volume of saline）， model group （SD， equivalent volume of saline）， AMD group （9.09 g·kg-1·d-1）， and melatonin group （MT， 0.27 g·kg-1·d-1）. Insomnia was induced in rats by self-made sleep deprivation box （4 weeks）. Circadian rhythm of spontaneous activity was evaluated by spontaneous activity video analysis system. Morphology of hypothalamus was observed based on hematoxylin-eosin （HE） staining， and the histomorphology of hypothalamus neurons and the Nissl's bodies based on Nissl staining. Western blotting was employed to detect the expression of hypothalamic proteins in cAMP-response element binding protein （CREB）/clock gene period （Per） pathway， and immunohistochemistry the expression of brain and muscle ARNT-like protein 1 （Bmal1）， Clock， Per1， and cryptochrome circadian regulator 1 （Cry1）. ResultThe model group demonstrated circadian rhythm disorder， as manifested by the significant increase in activity time in 6 designated time periods compared with the control group， and the rise in the activity speed and frequency （P<0.01）. Moreover， model group showed decrease in number of neurons which were sparsely arranged with shrunken or fragmented nuclei， reduction in number and loss of Nissl's bodies with light color， and drop in the relative expression of p-CREB and Per1， and the positive rate of Bmal1， Clock， Per1， and Cry1 （P<0.01）. Compared with model group， AMD group demonstrated reduction in time， speed， and frequency of activity （P<0.01）. Moreover， the AMD group also showed alleviation of neuronal damage （P<0.01）， and increase in the number of neurons with clear nuclei and cytoplasm in some， and the number of Nissl's bodies. AMD raised the expression of p-CREB and Per1 proteins， and the positive rate of Bmal1， Clock， Per1， and Cry1 （P<0.01）. ConclusionAMD ameliorated spontaneous circadian rhythm of sleep-deprived rats by regulating CREB/Per signaling pathway and further increasing the expression of Bmal1， Clock， Per1， and Cry1.
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Objective:To explore the relative genes that may influence kidney aging and verify the expression of clock gene Arntl in aging kidney. Methods:The differentially expressed genes between C57BL/6 male aging mice (24 months old) group and young mice (3 months old) group were identified by whole transcriptome sequencing, and the enriched biological pathways and key proteins were analyzed by bioinformatics methods. RT-qPCR and Western blotting were used to verify the mRNA and protein expression of Arntl.Results:(1) A total of 119 differentially expressed genes were screened between aging mice group and young mice group by whole transcriptome sequencing. Differentially expressed genes were mainly enriched in biological processes such as rhythmic process, circadian rhythm and circadian regulation of gene expression (all P<0.001). Protein-protein interaction analysis results showed that Nfil3, Hspa8, Arntl, Hlf, Rorc, Per3 and Npas2 and so on, were the key proteins in these differentially expressed genes. The results of RT-qPCR confirmed that the expression differences of clock genes Arntl, Nfil3, Npas2 and Per3 between aging mice group and young mice group were consistent with sequencing results (all P<0.05). (2) Compared with C57BL/6 young mice group and SAMR1 rapidly aging mice, the protein expression of Arntl in aging mice group and SAMP8 rapidly aging mice had downward trends. Conclusions:Clock genes and their circadian biological pathways may play an important role in the process of renal aging. The expression of Arntl in aging kidney has a downward trend.
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Rhythm of blood pressure refers to the circadian variation of blood pressure, which is regulated by clock genes. However, the rhythm disorder of blood pressure increases the risk of stroke. Taking the process of blood pressure regulation as a clue and focusing on the clock gene pathway, this article explores the possible mechanism of period gene regulating renin-angiotensin-aldosterone system in rhythm of blood pressure, so as to provide reference for the in-depth study of the relevant mechanism of rhythm disorder of blood pressure and search for a new target for the primary prevention of cerebrovascular diseases.
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ObjectiveTo investigate the association between the Clock T3111C and T257G gene polymorphisms and sleep epilepsy patients in Han population of Hunan province.MethodsThree hundred and eleven subjects with epilepsy ( sleep epilepsy group ( n =112 ),aperiodic group ( n =95 ),awakening epilepsy group ( n =104 ) ) and 300 sex- and age-matched healthy controls were enrolled in the study.Genomic DNAs were extracted from peripheral blood leucocytes by phenol-chloroform methods.The Clock T3111C and T257G polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP).Results(1) Two genotypes(TT and TC) were detected in Clock T3111C.The frequency of Clock site T3111C genotypes in all of the people was 86.09％ (TT,526/611),13.91％(TC,85/611),0( CC),T allele gene frequency was 93.04％ (1134/1222) and C allele gene frequency was 6.96％ (85/1222).There was no significant difference in genotype and gene distribution of Clock gene T3111C polymorphism between sleep epilepsy group,aperiodic group,awakening epilepsy group and control group.(2)Two genotypes(TT and TG) were detected in Clock T257G.The frequency of Clock site T257G genotypes in all of the people was 85.92％ (TT,525/611 ),14.08％ (TG,86/611 ),0( GG),T allele gene frequency was 92.96％ (1136/1222) and G allele gene frequency was 7.04％ (86/1222).There was no significant difference in genotype and gene distribution of Clock gene T257G polymorphisms between sleep epilepsy group,aperiodic epilepsy group,awakening epilepsy group and control group.(3)There was an almost complete correspondence (complete linkage disequilibrium) of bases between the positions 257 and 3111.ConclusionClock gene T3111C and T257G polymorphisms are not associated with sleep epilepsy in Han population of Hunan province.
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Low density lipoprotein receptor (LDLR) plays an important role in the cholesterol homeostasis. We examined the possible circadian regulation of LDLR and mechanism(s) underlying it. In mice, blood glucose and plasma triglyceride, total and high density lipoprotein cholesterol varied distinctively throughout a day. In addition, LDLR mRNA oscillated in the liver in a functional clock-dependent manner. Accordingly, analysis of human LDLR promoter sequence revealed three putative E-boxes, raising the possible regulation of LDLR expression by E-box-binding transcription factors. To test this possibility, human LDLR promoter reporter constructs were transfected into HepG2 cells and the effects of CLOCK/BMAL1, Hes1, and Hes6 expression were analyzed. It was found that positive circadian transcription factor complex CLOCK/BMAL1 upregulated human LDLR promoter activity in a serum-independent manner, while Hes family members Hes1 and Hes6 downregulated it only under serum-depleted conditions. Both effects were mapped to proximal promoter region of human LDLR, where mutation or deletion of well-known sterol regulatory element (SRE) abolished only the repressive effect of Hes1. Interestingly, hes6 and hes1 mRNA oscillated in an anti-phasic manner in the wild-type but not in the per1-/-per2-/- mouse. Comparative analysis of mouse, rat and human hes6 genes revealed that three E-boxes are conserved among three species. Transfection and site-directed mutagenesis studies with hes6 reporter constructs confirmed that the third E-box in the exon IV is functionally induced by CLOCK/BMAL1. Taken together, these results suggest that LDLR expression is under circadian control involving CLOCK/BMAL1 and Hes family members Hes1 and Hes6.