School of Biological and Biomedical Sciences, Durham University, Durham, UK.
J Invest Dermatol. 2011 Dec;131(12):2349-57. doi: 10.1038/jid.2011.227. Epub 2011 Aug 11.
Exogen is the process by which the hair follicle actively sheds its club fiber from the follicle. However, little is known about signals that govern the cellular mechanisms of shedding. Here, we have identified factors that are important in regulating either the retention or release of the hair club fiber from its epithelial silo within the follicle. Using the vibrissa follicle as our model, we isolated follicle segments containing club fibers and surrounding follicle tissue at different time points before their natural release from the hair follicle. We then performed microarray analysis to identify key molecular changes as the club fiber approached final release. Among the different classes of genes that were identified, we found changes in the expression pattern of protease inhibitors and proteases, suggesting that proteolysis may mediate fiber release, either through terminal differentiation or proteolytic cleavage. We validated transcriptional changes using reverse transcription-PCR, and further immunofluorescence analysis indicated that protease inhibitors surrounding the club fiber may have an important role in regulating the process of club fiber shedding. Our findings also highlighted that molecular differentiation of the innermost layer of cells immediately surrounding the club fiber, the companion(CL), is likely to be important in hair shedding.
外生作用是毛囊主动将其毛囊纤维从毛囊中脱落的过程。然而，对于控制细胞脱落机制的信号知之甚少。在这里，我们已经确定了在毛干纤维从毛囊内上皮管中保留或释放过程中起重要作用的因素。我们使用触须毛囊作为模型，在其自然从毛囊释放之前的不同时间点分离包含毛干纤维和周围毛囊组织的毛囊片段。然后，我们进行了微阵列分析，以确定毛干纤维接近最终释放时的关键分子变化。在鉴定出的不同基因类别中，我们发现蛋白酶抑制剂和蛋白酶的表达模式发生了变化，这表明蛋白酶解可能通过终末分化或蛋白水解切割来介导纤维释放。我们使用逆转录 - PCR 验证了转录变化，进一步的免疫荧光分析表明，围绕毛干纤维的蛋白酶抑制剂可能在调节毛干纤维脱落过程中起重要作用。我们的研究结果还表明，围绕毛干纤维的最内层细胞的分子分化，即伴侣细胞（CL），可能在毛发脱落中很重要。
