哺乳动物毛囊周期性生长调控机制的研究进展

毛囊是哺乳动物特有的皮肤附属器官,循环经历着生长期、退行期和休止期,每个时期都受一系列基因及其他相关因子的调控.目前,关于毛囊生长发育及调控机制的研究取得了较大的进展,尤其是在毛囊干细胞的活化、增殖、分化方面.本文简要介绍了毛囊的周期性生长过程,概括了褪黑素及毛囊相关基因和信号通路在毛囊上的研究进展,阐述了非编码RNA...     

MicroRNA对皮肤毛囊发育的调控机制

MicroRNA是参与转录后水平表达调控的重要因子, 在病理上成为药物作用的潜在靶点, 在生理上成为表型调控的潜在位点。目前, 对于microRNA的功能已有一定了解, 但其在皮肤毛囊发育中的作用机制还不完全清楚。近年来, 高通量测序技术为microRNA的鉴定提供了更准确、快速的途径, 研究发现一些microRNA能够影响皮肤毛囊细胞的分化和增殖, 其相关靶基因在调控毛囊周期性生长的过程中充当重要角色。文章综述了近年来microRNA在皮肤毛囊生长发育调控机制研究领域所取得的成果, 以期为后续开展绒山羊毛囊生长相关microRNA作用机制研究提供借鉴。     

鸟类毛囊形态发生中的分子信号

鸟类羽毛形态各异、功能多样,一直是国外研究的热点。毛囊是羽毛生长的载体,近年来,国外以鸡作为模式动物,对其毛囊生长发育规律、调控因子及其调控作用进行了大量研究。研究中发现,很多调控因子参与了毛囊形态发生过程,构成了极其复杂的信号网络。     

miRNA在调控皮肤和毛囊发育中的作用

表皮发生和毛囊的周期性再生涉及一系列基因的激活和沉默。近年来的研究表明, miRNA的表达谱在表皮和毛囊组织中存在组织特异性, 在毛囊周期性发育中存在阶段特异性。大量miRNA参与表皮和毛囊的发生, 色素的沉着以及毛囊的周期性发育过程, 不同类型细胞中的miRNA通过与信号通路和调控因子相互作用形成了一个全方位、多层次的网络调控系统。文章综述了miRNA调控表皮内稳态和毛囊周期性发育的一些研究 进展, 旨在丰富miRNA参与的基因调控网路的研究, 进而为人工调控miRNA进行疾病治疗和分子育种提供 帮助。     

毛囊干细胞研究进展

毛囊干细胞定位在毛囊隆突部,该部位细胞具有其它成体干细胞的共同特性,即慢周期、未分化、自我更新能力及体外增殖能力强等。CD34,K15,K19和Nestin可能作为毛囊干细胞的表面标记。毛囊干细胞在体外可诱导分化为神经元细胞,神经胶质细胞,角化细胞,平滑肌细胞和黑色素细胞等,而在体内（移植后）可分化为神经元、黑色素细胞等。在毛囊干细胞信号调控中涉及到许多的调控信号,主要包括WNT信号、BMP信号和NFATc1等基因的作用。     

常见毛囊细胞角蛋白在毛囊周期中的表达研究

目的探讨常见毛囊细胞角蛋白在毛囊周期中的表达特征。 方法取毛囊发育期、生长期启动、生长期、退化期和静止期的小鼠皮肤,石蜡切片后通过免疫荧光的方法,检测细胞角蛋白Krt5、Krt6、Krt10、Krt14、Krt15和Krt19的表达情况。 结果Krt5在静止期和生长期启动表达于所有毛囊上皮细胞,在其他时期表达不一致;Krt6表达于所有时期的外根鞘细胞和内根鞘细胞;Krt10表达于生长期和退化期的毛母质和内根鞘细胞,在其他时期表达不一致;Krt14在生长期和退化期表达于所有毛囊上皮细胞,在其他时期表达不一致;Krt15和Krt19表达于毛囊发育期、生长期启动和静止期的毛囊隆突区细胞,在生长期和退化期表达不一致。 结论角蛋白作为毛囊结构或毛囊干细胞标记物仅适用于特定的毛囊周期。研究者在使用毛囊角蛋白作为标记物时,应首先明确其在毛囊周期中的表达情况。     

毛囊干细胞

毛囊干细胞被认为是具慢周期性特点,但特定条件下具有较高增殖能力和克隆形成潜能的细胞。它们在形态学和生物化学上处于较原始的状态,常具有多潜能性。利用干细胞标记技术和克隆形成能力检测手段,人们发现毛囊干细胞主要存在于位于毛囊上半部的隆突部位。毛囊干细胞潜在的分子标记包括β1-整合素、α6-整合素、CD71、角蛋白19、p63和CD34,而在体内和体外它们的分子标记也不尽相同。毛囊隆突部位的干细胞能够分化成表皮、上皮性毛根鞘、发杆和皮脂腺。在个体发育过程中,它们具有分化成其他多种细胞系的能力。对于在毛发形态形成和生长周期中毛囊干细胞的行为,研究者们提出了多种假说,包括隆突激活假说和干细胞迁移假说。如今,毛囊干细胞主要应用于制备皮肤的代替品。     

毛囊移植术的临床方法讨论

目的：临床手术治疗雄激素源性脱发。方法：将受术者自身的健康毛囊移植至脱发区域,观察术后的头发生长。结论：毛囊移植术是一种治疗雄激素源性脱发的有效手段。     

新生小鼠不同部位皮肤毛囊早期发育差异的比较

目的观察出生后小鼠不同部位皮肤毛囊早期发育生长差异及细胞色素C的表达分布。方法对新生1~9日龄的KM小鼠背部、尾部和触须部皮肤取材,进行HE染色,用二步法免疫组织化学对组织进行细胞色素C进行表达分布检测。结果新生小鼠不同部位皮肤毛囊发育差异很大,这种差异不仅体现在形态差异上,而发育时间的差异也十分明显。小鼠出生后背部皮肤和尾部皮肤的毛囊发育都经过了一个非线性的发育和生长期,过了非线性的发育和生长期才开始快速生长,相比较尾部发育略迟于背部。触须部毛囊发育特征和背部尾部差异很大,一出生便可看到较成熟的触毛,没有经过稳定期便开始发育。结论通过形态学比较,结合CytC表达分布水平,发现新生小鼠不同部位皮肤毛囊早期发育存在形态和时间上的差异。     

小鼠毛囊发育分子遗传学机制研究进展

毛囊作为皮肤的附属器官,具有不断进行组织再生的特点,是研究干细胞的一种理想模型。毛囊发育机制十分复杂,其形态发生与持续终生的再生循环过程涉及表皮(上皮)和真皮(间充质)之间的相互作用。现已有相关的小鼠遗传模型被用于研究毛囊发育及再生的分子机制。该综述介绍最新的小鼠遗传学研究,主要涉及在毛囊发育过程中分别来自表皮和真皮中关键信号分子的敲除或过表达,以描绘一个控制毛囊发育和周期性循环的信号网络,为深入立体地理解毛囊发育机制和临床毛发疾病发病机制提供理论依据。     

In vitro methodology, hormonal and nutritional effects and fibre production in isolated ovine and caprine anagen hair follicles

Mammalian hair follicles are complex multicellular structures in the skin, which produce hair fibre under the influence of locally produced and systemic signalling systems. Investigation to determine mechanisms of regulation, follicular responses and the importance of nutritional supply have utilised a number of in vivo and in vitro approaches. Included in these are studies on isolated intact anagen secondary follicles singly or in groups with incubation in culture medium. These utilise techniques developed for investigation of follicles from human skin. Results from selected studies reviewed here demonstrate differences in capacity for hair growth and protein synthesis between secondary follicles from Angora and cashmere-bearing goats. Mohair follicles were shown to exhibit faster hair shaft elongation both in vivo and in vitro, to have greater DNA content per follicle and to deposit significantly more protein per follicle and per unit of DNA. Incubation of anagen mohair and cashmere follicles in the presence of melatonin or prolactin showed positive responses in hair shaft growth and protein synthesis to both signalling molecules. This result indicated directly acting effects on the follicle in addition to any indirect effects arising at a whole animal level in response to, for example, variation in photoperiod. Similarly, epidermal growth factor was shown to alter elongation and protein synthesis in mohair follicles and to produce, at higher concentration, club hair structures similar to effects observed in other species. The vitamin biotin was shown to be important in maintaining viability of isolated sheep secondary hair follicles where supplementation increased the proportion continuing to grow. Effects on growth and apparent protein synthesis suggested comparatively lesser effects on follicles, which remained viable. Histology on follicles indicated effects of biotin deficiency in reducing proliferation of basal keratinocytes. The final study, included in this review, demonstrated that supply of the essential sulphur-containing amino acid l-methionine was necessary to maintain the viability and growth of mohair follicles. l-cysteine was not required in the presence of l-methionine, although there was evidence of an optimisation when both amino acids were present in adequate concentrations. Consideration is given to the importance of transport mechanisms and capacity to utilise absorbed nutrients when considering optimising nutritional supply to individual follicles. These may then provide targets for attainment in applied nutrition of animals in vivo.     

皮肤毛囊发育的转录组研究进展

近年来,转录组测序技术在动物重要经济性状受复杂基因网络的调控研究领域取得了显著的成果。作为哺乳动物皮肤的衍生物,毛囊是唯一具有高度自我更新能力、独特的可再生器官,毛囊细胞经增殖分化最终形成毛发。已有的研究表明,诸多生长因子及其受体作为体内分泌协调基因的重要因素,对毛发的生长发育起着重要的调控作用。文章综述了近年来转录组测序技术在人、小鼠及羊等生物的皮肤毛囊发育和再生过程中基因调控方式的研究进展,旨在为今后人工干扰绒毛周期生长发育和分子育种提供理论依据,同时也为皮肤毛囊相关疾病的临床治疗提供新思路。     

P75NTR在绒山羊毛囊生长周期中的表达

实验旨在研究绒山羊（Capra hircus）毛囊生长相关基因的表达规律,为绒山羊分子育种提供参考。本实验采用RTPCR、组织免疫荧光、Western blot等方法,研究神经营养素受体P75NTR在辽宁绒山羊皮肤组织中的表达和分布情况。结果表明：在毛囊生长周期的三个时期,均监测到P75NTR mRNA及蛋白的存在,P75NTR的荧光信号在退行期要强于其他两个时期,且在退行期毛囊外根鞘细胞中检测到P75NTR的高表达。以上结果表明,P75NTRmRNA及蛋白的表达与毛囊生长周期变化有一定的相关性,P75NTR受体在绒山羊的毛囊周期性变化中发挥着重要的功能。     

cgVEGF164基因对小鼠毛囊生长的影响

血管内皮生长因子(vascular endothelial growth factor, VEGF)是一种二聚体糖蛋白,能够诱导毛囊血管内皮细胞的增殖和迁移,调节毛囊周围毛细血管生成,进而影响毛囊的生长发育。已知cgVEGF164是绒山羊VEGF-A基因的一种主要剪接变体,但cgVEGF164基因是否具有调控毛囊生长发育的作用目前尚不清楚。为初步探究cgVEGF164基因对毛囊生长的影响及其机制,本研究通过原核显微注射制备cgVEGF164转基因过量表达小鼠。通过HE染色法比较转基因小鼠和非转基因对照小鼠毛囊的直径和密度,利用WesternBlot检测小鼠背部皮肤中信号蛋白ERK1/2、AKT1、LEF1的磷酸化水平。本研究成功获得5只阳性cg VEGF164转基因小鼠(雌雄比为4:1,阳性率8.5%);与非转基因对照小鼠相比,转基因小鼠毛囊直径增大、密度增加;经检测转基因小鼠中ERK1/2、AKT1、LEF1的磷酸化水平均上调。结果表明,cgVEGF164基因具有促进小鼠毛囊生长的作用,推测该功能可能与cgVEGF164影响ERK1/2、AKT1和LEF1等信号蛋白的磷酸化有关。     

Demodex spp. in the hair follicles of rhesus macaques (Macaca mulatta)

The perineal or perineal and facial skin were evaluated on 53 rhesus macaques as part of a necropsy protocol. Microscopic evaluation of H & E stained skin sections revealed 19 animals positive for Demodex spp. Mites were seen within all portions of the hair follicles. Infestation varied from minimal to severe. Mites were found in macaques of all ages and in both sexes. Reaction to the mites ranged from no reaction, to minimal follicular epidermal hyperplasia to furunculosis. Immune status of the animal did not determine infestation but immune compromised macaques had more severe lesions. This is the first known report of Demodex spp. in rhesus macaques.     

Organotypic culture of outer root sheath cells from human hair follicles using a new culture device

Summary A new culture vessel for the growth of cells on biological substrata and under organotypic conditions is described. This device, named Combi-ring-dish (CRD), is composed of four concentric rings designed to take up one or several substrata on which cells can be grown either immersed in culture medium or exposed to air and fed from underneath. Using the CRD, outer root sheath cells, isolated from plucked human hair follicles and plated on growth-arrested 3T3 feeder layers, were grown on native collagen lattices populated with living human fibroblasts. After reaching confluence, the immersed cultures were recombined (in vitro) with pieces of freeze-killed dermis and grown further, exposed to air. Thus by mimicking epidermal growth conditions, differentiation was dramatically improved, compared to control cultures on plastic substratum. Virtually all morphologic features of interfollicular epidermis developed. This seems a suitable model to investigate the differentiation potential of human hair follicle cells.     

Developmental and hormonal regulation of cumulus expansion and secretion of cumulus expansion-enabling factor (CEEF) in goat follicles

The objective of this article was to study the developmental and hormonal regulation of cumulus expansion and secretion of cumulus expansion-enabling factor (CEEF) in goat follicles. M-199 medium was conditioned for 24 hr with cumulus-denuded oocytes (DOs), oocytectomized complexes (OOXs), or mural granulosa cells (MGCs) from goat follicles of different sizes. Mouse OOXs and eCG were added to culture drops of the conditioned medium and cumulus expansion was scored at 18 hr of culture to assess CEEF production. While mouse OOXs did not expand, goat OOXs underwent full cumulus expansion when cultured in nonconditioned eCG-supplemented M-199 medium. When cultured in nonconditioned medium containing 10% follicular fluid (FF) from goat medium (2-4 mm) and small (0.8-1.5 mm) follicles, 71-83% mouse OOXs expanded; but expansion rates decreased (P < 0.05) at either lower or higher FF concentrations. FF from large (5-6 mm) follicles did not support mouse OOX expansion at any concentrations. While medium conditioned with DOs from follicles of all the three sizes supported expansion of 80-90% mouse OOXs, medium conditioned with mature DOs had no effect. While cumulus cells from follicles of all the three sizes secreted CEEF in the absence of gonadotropins, MGCs from large follicles became gonadotropin dependent for CEEF production. Both FSH and LH stimulated CEEF production by large follicle MGCs, but FSH had a shorter half-life than LH to expand mouse OOXs. Few meiosis-incompetent goat oocytes from small follicles underwent cumulus expansion when cultured in medium conditioned with goat DOs or cocultured with goat COCs from medium follicles. It is concluded that (1) goat cumulus expansion is independent of the oocyte; (2) the limited CEEF activity in FF from large follicles was due mainly to the inability of MGCs in these follicles to secret the factor in absence or short supply of gonadotropins; (3) the cumulus expansion inability of the meiosis incompetent goat oocytes was due to the inability of their cumulus cells to respond to rather than to produce CEEF.     

Detection of Bim and Puma in mouse hair follicles using immunofluorescence and TUNEL assay double staining

Apoptosis in hair follicles often is studied under pathological conditions; little is known about apoptotic mechanisms during normal hair follicle formation and maintenance. We investigated proteins of intrinsic apoptotic pathway, Bim and Puma, during hair follicle development and the first catagen stage using immunofluorescence to describe their expression patterns and to correlate them with apoptosis as determined by TUNEL assay. Both proteins were found in developing follicles. Bim and Puma overlapped apoptosis only partially during physiological apoptotic stage and they were present in non-apoptotic parts of the follicles. Our findings suggest that these primary apoptotic molecules participate in postnatal development and maintenance of hair follicles.     

Morphological and histological features of the integument of the New Zealand sea lion Phocarctos hookeri

Abstract

Morphological and histological features of the integument of 2 Hooker’s sea lions, obtained dead in February, were examined. In a 3- week-old pup there were 7 rows of mystacial vibrissae, comprising 40 on the left side of the muzzle and 38 on the right. In the skin of the torso the guard hairs were in the quiescent phase of their growth cycle. In a 2½-year-old specimen a moult was imminent; guard hairs in quiescent follicles were about to be displaced by fibres in developing follicles. Histological features of the older sea lion, which may have been age-related, were coarser collagen bundles in the reticular layer of the dermis and a greater number of secondary follicles. In guard hair follicles of both animals the sweat gland duct opened above the sebaceous gland duct.