Klotho基因与心血管病的关系及研究现状

Klotho（Kl）基因是与人类衰老密切相关的基因，Kl基因表达缺陷的小鼠可出现类似于人类衰老的各种表型，如寿命缩短、不育症、动脉硬化、皮肤萎缩、骨质疏松、肺气肿等。近年来对Kl基因在心血管病中的作用逐渐受到重视，现将有关研究现状综述如下。[第一段]     

抗衰老Klotho基因的功能及与人类疾病的关系

抗衰老基因Klotho(KL)是1997年研究自发型高血压时发现的与衰老有关的基因[1].该基因突变小鼠会过早出现与人类衰老相似的多种表现,并使其寿命缩短,而通过转基因使KL过度表达会减轻小鼠的衰老症状,延长寿命.研究显示KL基因缺陷鼠的寿命仅为野生鼠的5%～6%[2],而其过度表达会使小鼠的寿命延长(雌性和雄性分别延长20%和30%)[3].但是,KL基因的基础研究与人类衰老性疾病关系的研究较少.     

Klotho生物学功能与Insulin/IGF-1通路关系的研究进展

Klotho基因是一个与衰老密切相关的基因,他参与维生素K和钙、磷的代谢,保护心血管系统,影响机体的免疫功能,对衰老及衰老相关性疾病进行调节.胰岛素/胰岛素样生长因子-1(insulin/insulin-like growth factor-1,Insulin/IGF-1)信号通路也参与衰老及衰老相关性疾病的调节,其发...     

Klotho基因及其多态性的研究进展

Klotho基因是Kuro等[1]于1997年发现的与衰老有关的新基因,并用古希腊神话中纺织生命之线女神的名字命名.Klotho基因被敲除的小鼠(KL-/-小鼠)可出现类似人类衰老的各种表型,如寿命缩短、不育症、动脉硬化、皮肤萎缩、骨质疏松、肺气肿等.近年来对klotho基因多态性与疾病的关系逐渐受到重视,现将有关研究现状综述如下.     

CD4＋CD25＋调节性T细胞与衰老关系的研究进展

衰老伴随着免疫系统多种功能和表型的改变,使机体免疫力下降。CD4＋CD25＋调节性T细胞址体内具有免疫抑制活性的一群细胞,它在维持自身内环境稳定、抑制移植排斥反应以及防止自身免疫忤疾病的发生等方面发挥重要的保护作用,同时也是免疫力衰退的重要因素之一。调节性T细胞在机体衰老过程中发生变化,并发挥重要的作用。现将衰老过程中调节性T细胞的数量、功能、表型等的变化,以及调节性T细胞与老年相关性疾病的关系进行综述。     

KLOTHO基因表达产物的研究进展

Klotho基因是一种主要在肾脏和脑组织表达的基因,其表达产物有膜型和分泌型2种蛋白,二者分别是膜结合受体和体液因子,能通过如影响细胞结构,调节维生素D和钙、磷代谢,保护心血管系统,影响机体免疫功能等多种途径对衰老及衰老相关性疾病进行相应的调节。Klotho基因敲除后的小鼠过早出现和人类衰老相似的多种行为和病理生理改变,如寿命缩短、运动失调、肺气肿、动脉粥样硬化、骨质疏松和血管内皮功能障碍等。用Klotho基因进行遗传补救治疗后,这些症状得到缓解。因此Klotho基因的表达产物有望成为防治老年性疾病的有效药物,对其在血清中的含量进行检测还有望作为诊断衰老性疾病的指标。     

血管紧张素Ⅱ-1型受体基因与血管相关代谢性疾病关系的研究进展

血管紧张素Ⅱ-1型受体基因(AGTR1)是人类编码AT1受体的基因,是肾素-血管紧张素系统(RAS)的3个关键基因之一,因为该基因与一些代谢性疾病相关,本文就近年来AGTR1基因与血管相关代谢性疾病的相关性研究现况作一简要综述。     

衰老的生物学研究进展

本文回顾了衰老研究中遇到的难题，包括选择模型，区别病理变化与内生的衰老变化、继发变化与原发变化以及对特殊老年变化在衰老中的重要性。综述了以往的研究途径、特别探讨了遗传与衰老的关系及对长寿保障基因所开展的实验。最后提出未来衰老的研究途径，即查不同水平的衰老变化，对衰老不利因素的基因定位和实验性影响调节长寿或衰老表型的基因。     

超正常化血管衰老的研究进展

血管衰老是与增龄相关的动脉壁硬度增加现象.动脉结构和功能的过早改变引起的早期血管衰老,是血管衰老的一种极端表型.超正常化血管是近年发现另一种极端表型,即与年龄不相符的异常低的动脉硬度.这种极端表型为研究血管衰老的保护机制提供了新途径.该文介绍了超正常化血管衰老的人群特点、发生机制、筛查识别等.     

特发性肺纤维化衰老相关发病机制及治疗的研究进展

特发性肺纤维化(IPF)是一种最常见的特发性间质性肺炎,是基因易感性和环境因素等复杂病理机制相互作用的结果,好发生于中老年人群,年龄为IPF重要的危险因素.近年来对衰老生物学的研究有了较大进步.目前提出的许多衰老的特征如基因组不稳定性、端粒磨损、基因表观遗传学的改变、自噬降低、线粒体功能失调、衰老相关分泌表型、内质网应...     

Role of the Klotho Gene in Bone and Mineral Metabolism

Klotho was originally identified when a random insertional mutation disrupting the mouse gene caused an abnormal phenotype with accelerated aging and shortened lifespan. Klotho appears to play an important role in the renal handling of calcium and phosphate, in part by interacting with the FGF23 signaling system. In general, klotho tends to decrease phosphate retention and 1,25-dihydroxyvitamin D3 synthesis. It directly stimulates calcium reabsorption in the kidney and tends to increases serum calcium, but may have opposite indirect effects related to the changes in vitamin D metabolism. Klotho may also influence the response of the parathyroids to hypocalcemia and may interact with other biological systems, including Wnt, OPG/RANKL, insulin/IGF-I, and sex steroids. The actual relevance of klotho in human physiology has been recently illustrated by the identification of some rare patients with loss-of-function and gain-of-function mutations of the Klotho gene. Several studies also suggest that certain polymorphisms of the gene may influence human aging and the development of age-related diseases, such as arteriosclerosis or osteoporosis, but further investigations are needed to elucidate their true importance.     

The frequency of Klotho KL-VS polymorphism in a large Italian population,from young subjects to centenarians,suggests the presence of specific time windows for its effect

In mice a defect of Klotho gene expression results in multiple aging-like phenotypes including short lifespan, osteoporosis and atherosclerosis, while its over-expression suppresses aging and extends lifespan. Contrasting data have been reported as far as the importance of the functional variant of Klotho termed “KL-VS” on human longevity, depending on the average age of the old subjects that were compared with young controls. We therefore performed a study on a large Italian population sample including people from very young to very old age (centenarians). A total of 1,089 (669 women and 420 men) unrelated individuals from 19 to 109 years, born and residing in northern and central Italy, were subdivided into three age classes defined on the basis of the survival curve constructed using Italian demographic mortality data, and genotyped for the KL-VS allele. We found a significant increase of the heterozygous Klotho genotype in the class of elderly people compared to young controls. On the contrary, no difference was present between centenarians and young controls. Such a non monotonic trajectory is evident only when a large, comprehensive age range is investigated, and is compatible with the hypothesis that this KL-VS heterozygous genotype is favorable for survival in old people, its beneficial effect decreasing thereafter, and becoming no more evident at the extreme ages. Such unusual age-related changes in the Klotho KL-VS genotype frequency is compatible with the hypothesis that alleles and genotypes involved in aging and longevity may exert their biological effect at specific time windows.     

Klotho protein activates the PKC pathway in the kidney and testis and suppresses 25-hydroxyvitamin D3 1alpha-hydroxylase gene expression

Homozygous Klotho mutant (kl ^−/−) mice exhibit a variety of phenotypes resembling human aging, including arteriosclerosis, infertility, skin atrophy, osteoporosis, and short life span. Calcium abnormality, one of the phenotypes in kl ^−/− mice, is thought to be due to the elevated gene expression of 25-hydroxyvitamin D₃ 1α-hydroxylase in the kidney. We studied 25-hydroxyvitamin D₃ 1α-hydroxylase gene expression using a Klotho plasmid that we had previously constructed for Klotho protein production. It was found that Klotho protein medium upregulated cAMP and the PKC pathway, and suppressed 25-hydroxyvitamin D₃ 1α-hydroxylase in kidney cells. However, both cAMP and PKC are known to elevate 25-hydroxyvitamin D₃ 1α-hydroxylase gene expression, therefore, another unknown calcium regulation pathway using Klotho protein medium might exist. Furthermore, we found that activation of the PKC pathway by Klotho was observed only in the kidney and testis, where the Klotho gene is expressed, although activation of the cAMP pathway was observed in any kind of cell. These data suggest that calcium regulation through 25-hydroxyvitamin D₃ 1α-hydroxylase by Klotho depends on non-cAMP and a non-PKC pathway and that the Klotho protein may have different signaling pathways, depending on the Klotho gene expression in different cells and organs.     

山茱萸多糖对D-半乳糖致衰老小鼠肾组织中Klotho基因表达的影响

目的研究山茱萸多糖对D-半乳糖致衰老小鼠肾组纵中Klotho基因表达变化的影响。方法昆明小鼠60只,随机分为青年对照组、衰老模型组、山茱萸多糖组,每组20只。采用D-半乳糖法制作衰老模型,以灌胃法给山茱萸多糖组小鼠灌服山茱萸多糖。采用分光光度法检测总抗氧化能力（T—AOC）和Mn—SOD活性水平,RT—PCR法检测Klotho和Mn—SOD基闪表达水平,Westernblot法检测Klotho蛋白表达最。结果与对照组比较,衰老组小鼠肾组织中Klotho基因、Mn—SOD活性和基斟表达均下降（P〈0．01）,总抗氧化能力（T—AOC）下降（P〈0．01）;与衰老模型组比较,山茱萸多糖组小鼠Klotho基困和蛋白表达明显升高（P〈0．01）、Mn-SOD基因表达和Mn-SOD活性明显增高（P〈0．01）,总抗氧化能力也显著提高（P〈0．01）。结论山茱萸多糖可能通过上调衰老小鼠肾组织中的Klotho表达和提高衰老小鼠抗氧化能力岍发挥抗衰老的作用。     

小鼠全长膜型Klotho蛋白cDNA表达体系的构建与应用

目的克隆编码小鼠膜型Klotho(mKL)蛋白的cDNA片段,构建、包装Klotho重组腺相关病毒表达体系,并检测rAAV/mKL载体表达功能。方法选择RT-PCR扩增小鼠全长mKL蛋白的基因片段,将该片段亚克隆至腺相关病毒载体pAAV-IRES-hnGFP,采用酶切及DNA测序鉴定;利用AAV-293细胞包装rAAV/mKL,经转染7901细胞,检测其Klotho表达情况。结果本文成功克隆出序列信息和读码框完全正确的3 064 bp的小鼠Klotho基因片段,并构建pAAV/mKL克隆。在AAV-293细胞中包装出rAAV/mKL,病毒原液转染7901细胞后其Klotho mRNA表达上调,而细胞上清液Klotho蛋白也明显增加(P<0.01)。结论成功构建小鼠Klotho重组腺相关病毒载体(pAAV/mKL),获得了rAAV/mKL,并经转染7901细胞验证其基因表达功能正常,这就为进一步研究Klotho基因治疗衰老相关性疾病提供了技术基础。     

Atherosclerosis and Cardiovascular Diseases in Progeroid Syndromes

Hutchinson–Gilford progeria syndrome (HGPS) and Werner syndrome (WS) are two of the representative genetic progeroid syndromes and have been widely studied in the field of aging research. HGPS is a pediatric disease in which premature aging symptoms appear in early childhood, and death occurs at an average age of 14.5 years, mainly due to cardiovascular disease (CVD). Conversely, WS patients exhibit accelerated aging phenotypes after puberty and die in their 50s due to CVD and malignant tumors. Both diseases are models of human aging, leading to a better understanding of the aging-associated development of CVD. In this review, we discuss the pathogenesis and treatment of atherosclerotic diseases presented by both progeroid syndromes with the latest findings.     

双歧杆菌脂磷壁酸抗氧化作用的实验研究

目的 通过研究双歧杆菌表面分子脂磷壁酸（LTA）对D-半乳糖致衰老小鼠氧化系统指标及Klotho基因表达变化的影响,探讨双歧杆菌LTA延缓衰老的分子机制。方法 在D-半乳糖诱导小鼠亚急性衰老的同时,每日腹腔注射双歧杆菌LTA。用试剂盒检测小鼠肾脏组织SOD活性及MDA的含量,同时用RT-PCR、Western blot及免疫组化方法检测各组小鼠肾脏组织Klotho基因表达情况。结果 与青年对照组小鼠比较,衰老模型组小鼠SOD活性显著下降,MDA含量显著升高,Klotho基因在转录和翻译水平表达均明显下降;而双歧杆菌LTA能显著逆转上述变化。结论 双歧杆菌LTA可能通过提高衰老小鼠的抗氧化活性及上调Klotho基因表达,从而发挥其延缓衰老的作用。     

Klotho与心血管疾病的关系及其生物学机制

Klotho是重要的内源性多效蛋白,参与衰老和钙磷代谢等病理生理过程,与心血管疾病密切相关。近期的临床研究发现低水平的Klotho与更多的心血管危险因素关联,并能预测心血管疾病的发病风险和不良预后;基础研究也表明Klotho在维持血管稳态和正常心功能中发挥了至关重要的作用。Klotho可以促进一氧化氮(NO)的生成,抑制炎症因子和黏附分子的表达,介导抗氧化、抗凋亡、抗衰老的生物学效应,延缓动脉粥样硬化及血管钙化,并抑制心肌肥厚和纤维化。Klotho或可作为一个新的干预靶点,为心血管疾病的防治提供新的思路。文章就Klotho与心血管疾病的关系及其潜在的生物学机制做一综述。     

Mediation of unusually high concentrations of 1,25-dihydroxyvitamin D in homozygous klotho mutant mice by increased expression of renal 1alpha-hydroxylase gene.

Homozygous klotho mutant (kl-/-) mice exhibit multiple phenotypes resembling human aging. To elucidate the molecular basis of these singular phenotypes, we focused on the mechanisms underlying increased serum concentrations of calcium and phosphorus in kl-/- mice. Serum concentrations of calcitonin and PTH of kl-/- mice were normally up- and down-regulated, respectively, in response to the high levels of calcium. On the other hand, despite the high concentrations of calcium, serum levels of 1,25-dihydroxyvitamin D [1,25-(OH)2D] in kl-/- mice were significantly higher than that of wild type (WT). The expression of 25-hydroxyvitamin D 1alpha-hydroxylase gene, the key enzyme of vitamin D metabolism, was also greatly enhanced in kidneys of kl-/- mice. Furthermore, the normal genetic responses to administered 1,25-(OH)2D3, such as down-regulation of the 25-hydroxyvitamin D 1alpha-hydroxylase gene and up-regulation of 24-hydroxylase and VDR genes, were apparently impaired in kl-/- mice. These findings suggest that this deterioration in the vitamin D endocrine system may result in many of the phenotypes in kl-/- mice through effects of increased levels of calcium and phosphorus and 1,25-(OH)2D. Klotho protein may participate in calcium and phosphorus homeostasis via the regulation of the 1,25-(OH)2D signaling pathway.