成黑色素细胞生成过程中信号调节的研究进展

动物体内的黑色素细胞合成了黑色素从而决定其肤色和毛色。全身各处的黑色素细胞有2种来源:①由神经管上皮细胞分化而来的视网膜色素上皮细胞;②由神经嵴细胞在胚胎发育早期分化为成黑色素细胞进而发育成熟为黑色素细胞从而行使其功能。通过对小鼠和人类的发育遗传学研究,结果表明神经嵴细胞衍生的黑色素细胞的发育分化是一个非常复杂的过程,受到多重信号因子的调控。其中影响黑色素细胞发育过程的转录因子有SOX10、MITF和PAX3,信号通路有KIT及其配体KITL信号通路、WNT/β-catenin信号通路、EDN3及其受体EDNRB信号通路。MITF被认为是黑色素细胞发育过程中非常关键的调控因子,而3条通路也被认为与神经嵴细胞来源的黑色素细胞的发育有极为密切的关系且能调节MITF功能及其活性。作者总结了这个领域的研究进展并指出早期神经嵴细胞的发育调控可能是乌骨鸡和乌骨绵羊乌质性状形成的根本原因。     

黑色素细胞调控小眼畸形相关转录因子的研究进展

黑色素细胞的主要功能是合成黑色素。黑色素是皮肤受紫外线照射后"自我保护"形成的产物,在黑色素细胞的亚细胞器—黑素小体中合成。黑色素的形成过程受到了许多基因的调控,其中小眼畸形相关转录因子(MITF)对黑色素细胞发育、增殖和存活至关重要。本文首先对MITF基因的结构和功能进行介绍,其次对MITF参与的相关分子信号通路,以及MITF在黑色素细胞的生长发育、黑色素的合成的影响进行综述,最后概述了MITF在人类中的突变影响,并对未来的研究方向进行展望。有助于探明哺乳动物黑色素的合成的分子机制,为哺乳动物毛色的形成提供理论依据。     

小眼畸形相关转录因子（MITF）的研究进展

小眼畸形相关转录因子（MITF）是一种具有典型螺旋—环—螺旋—亮氨酸拉链结构的转录因子,目前已经发现其存在于许多物种中,参与生物体生长、发育、分化和功能调节等各个方面。对MITF的研究进展进行了综述,以期为今后相关研究的开展提供有益参考。     

CDK5对羊驼皮肤黑色素细胞TYR和MITF mRNA表达的调节

为了证实CDK5是否参与羊驼毛色的形成,本研究主要对CDK5在羊驼黑色素细胞中调节TYR和MI TF的表达进行了研究.本研究首先采用免疫组织化学方法检测CDK5在羊驼皮肤黑色素细胞中的定位,再通过脂质体将CDK5转染于羊驼皮肤黑色素细胞,之后通过Western blot和qRT-PCR的方法检测转染后黑色素细胞中CDK5蛋白、TYR和MITF mRNA的表达.免疫组化结果显示CDK5位于黑色素细胞的胞质和细胞核内;Western blot结果显示转染组黑色素细胞中CDK5蛋白表达量明显高于对照组;qRT-PCR结果显示CDK5可下调MITF的表达,同时上调TYR的表达,转染组黑色素细胞中MITF和TYR mRNA的表达水平分别是对照组细胞的0.264 9和3.931 3倍.结果揭示CDK5可能通过调节黑色素细胞核中TYR和MITF mRNA的表达,从而参与调控羊驼毛色形成.     

黑色素形成调控机理及乌骨绵羊黑色素沉积候选基因研究进展

黑色素(melanin)产生于黑色素细胞,是由酚类或吲哚类物质氧化聚合而成的不易溶于水的聚合体,广泛存在于微生物和动植物机体,具有消除自由基、抗氧化、抑制病毒感染、激活免疫系统、提高机体免疫力、延缓衰老等生理功能。酪氨酸在酪氨酸酶作用下生成多巴,多巴经过系列复杂的生物学反应形成黑色素。现有研究发现,多种信号通路(α-MSH/MC1R/cAMP信号通路、Wnt/β-catenin信号通路、PI3K/Akt/GSK3β信号通路、MAPK信号通路等)及相关调控因子(MITF、MC1R、TYR等)参与了黑色素的形成过程。一般认为,哺乳动物黑色素细胞主要分布于皮肤和毛囊组织,而乌骨绵羊的内脏组织也能存在大量黑色素细胞,其形成机制尚不明确。乌骨绵羊的乌质性状是重要的经济性状,与其营养和药用价值密切相关,受机体组织黑色素沉积程度的影响。文章简述了黑色素的理化性质、生物功能及其合成路径,回顾了近年来发现的调控动物机体黑色素合成的信号通路及其作用机理,总结了影响乌骨绵羊黑色素沉积和分布规律相关候选功能基因的研究现状,以期为深入研究黑色素沉积调控机理及候选功能基因应用于生产实践提供参考。     

靶向MAPK信号通路调控脂肪细胞分化的microRNAs

脂肪细胞分化是一个多能间充质干细胞(MSCs)逐渐向成熟脂肪细胞分化的复杂过程,该过程受很多转录因子、激素以及信号通路相关分子的严格调控。体内外的试验表明,microRNAs(miRNAs)也参与了脂肪细胞分化的调节,且可以靶向转录因子和信号通路中的关键分子发挥作用。丝裂原活化蛋白激酶(MAPK)信号通路是真核细胞将胞外信号转导至胞内引起细胞反应的一类重要信号系统,研究证明,miRNAs可以靶向MAPK信号通路中的某些基因,影响该通路的信号转导,参与脂肪细胞分化的调控。因此本文总结了近几年有关miRNA改变MAPK信号转导,实现调控脂肪细胞分化功能的研究,以期为深入了解脂肪细胞分化的机制,为治疗脂肪型疾病提供新的思路。     

黑色素细胞相关调控因子研究进展

黑色素细胞是皮肤组织中的一种特殊细胞,黑色素细胞能够产生黑色素并且传递给周围的角质细胞。黑色素传递并停留在这些角质细胞中,能够防止光线辐射对染色体产生损伤,对细胞产生一定的保护作用。黑色素的合成受到许多复杂的调控因子的调控,小眼畸形转录因子在调控黑色素的合成及黑色素细胞的迁移和生存起着非常重要的作用。在小鼠中,干细胞因子或者是它的感受器c-Kit的突变会导致黑色素细胞异常表型。黑色素细胞通过福斯匹林和α黑色素细胞刺激素与黑素皮质素受体结合刺激黑色素的生成;刺鼠信号蛋白会抑制酪氨酸蛋白酶的活性,进而减少黑色素的产量。WNT信号对于神经嵴细胞分化为黑色素细胞有影响,影响黑色素细胞的数量进而影响黑色素的产量。促肝细胞生长素是酪氨酸激酶的感受器,能够促进和保持黑色素细胞产生黑色素的活性。控制合成内皮缩血管肽的受体及配体EDN3的基因的突变会导致黑色素细胞的缺失。     

Heartworm in dogs in Canada in 1984

In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal.

Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection.

     

Heartworm in dogs in Canada in 1983

In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario.

Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously.

     

Heartworm in dogs in Canada in 1991

In late November 1991, 1883 clinics in Canada were sent a questionnaire to assess the status of Dirofilaria immitis in dogs in 1991 and there was a 60.0% response. There were 344,031 dogs tested for heart-worm (HW), 627 were found infected and the prevalence of HW infection was 0.18%. There were 417 dogs with HW in Ontario, 116 in Manitoba, 38 in Quebec, 53 in British Columbia, three in Alberta, and one in Nova Scotia. In British Columbia, all of the infected dogs but one were from the Okanagan valley which, as from 1991, is a new focus of infection in Canada. Most dogs with HW had not been on preventive medication in 1990, and the prevalence among dogs tested and unprotected was 0.59%. That prevalence was considerably higher in endemic areas. Companion dogs, over three years of age and maintained primarily outdoors in rural areas, were most frequently infected. One cat was diagnosed with D. immitis and 33 dogs had Dipetalonema reconditium.     

Heartworm in dogs in Canada in 1985

In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%).

Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada.

     

Heartworm in dogs in Canada in 1988

In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%).     

Heartworm in dogs in Canada in 1989

In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated.

Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively.

     

Heartworm in dogs in Canada in 1987

In late November 1987, 1246 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1987, and 50% of them responded. Veterinarians reported that 165,428 dogs were blood tested for heartworm disease and 511 dogs were found with D. immitis microfilariae. Another 78 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1987 as 589 (0.35%).     

Heartworm in dogs in Canada in 1986

In late December 1986, 1224 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1986; 46% of them responded. Veterinarians reported that 150,989 dogs were blood-tested for microfilariae and 869 dogs were found with heartworm. Another 65 dogs were amicrofilaremic but diagnosed with heartworm disease and one was found with heartworm at necropsy to give the total number diagnosed in 1986 as 935 (0.62%).

Heartworm was reported from Manitoba, New Brunswick, Ontario and Quebec, but most (810) of the cases were from Ontario. South-western Ontario continued to be the primary focus of the infection in Canada. There were 103 cases reported from Quebec, mostly from and around Montreal, and 21 cases from Manitoba, from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 33% of the cases were observed with clinical signs of heartworm disease and 81% had a history of not having left Canada.