基底膜成分IV型胶原与其受体DDR1结合在毛囊黑素干细胞移行生成黑素细胞过程中的作用与机制研究

Melanocyte stem cells (MSC) in hair follicle bulge are melanocytes reservoir of skin and hair follicle. MSC can migrate to generate melanocyte precursor (MP). Next then, MP migrate upward along the basement membrane to differentiate into epidermal melanocytes (EMC) to make repigmentation for vitiligo, and migrate downward to generate hair matrix melanocytes (FMC) for providing pigment for hair shaft. Thus far, the mechanism of follicular basement membrane regulating MSC migrating and differentiating into FMC and EMC is still unknown. Some previous results suggested that type IV collagen (CIV) in basement membrane combined its receptor DDR1 promoted migration of MSC in vivo and vitro, and blocking this combination between CIV and DDR1 prevented MSC to generate EMC and FMC. So we hypothesize that the combination between CIV and DDR1 would probably regulate MSC migration to generate MP through the interactions with classical intercellular signal pathway Wnt/ β -catenin and TGF- β /Smad2 in the stem cell niche, and further the combination between CIV and DDR1 promote MP to migrate and generate EMC and FMC by regulating intracellular signal pathways. Therefore, we choose the process that MSC migrate and generate EMC and FMC as the object of study. Further more, we will use some specific experimental methods to activate and block the process of MSC generating EMC and FMC in C57BL/6J in vivo. Then A whole set methods including immunofluorescence, follicle reconstruction in vivo, cell migration and others will be employed to investigate the effect and mechanism which the combination between CIV and DDR1 regulate MSC to migrate and generate EMC and FMC on the levels of molecules, cells, tissues and animals. All these results will finally provide new ideas for the clinical treatment of vitiligo.

毛囊隆突部黑素干细胞(MSC)可生成前体黑素细胞(MP),MP上行生成表皮黑素细胞(EMC),下行生成毛母质黑素细胞(FMC)。迄今对毛囊基底膜调控MSC移行生成FMC和EMC的机制不详。研究结果提示基底膜成分IV型胶原(CIV)与其配体DDR1结合可促MSC移行，阻断该结合可阻止MSC生成EMC和FMC。为此提出假说：①CIV结合DDR1可能通过与干细胞巢内细胞间的经典信号通路Wnt/β-catenin和TGF-β/Smad2相互作用诱导MSC脱离干细胞巢生成MP；②CIV结合DDR1再通过细胞内信号途径调控MP移行生成EMC和FMC。为此，我们将采用特异性激活与阻断等技术调控C57BL/6J小鼠毛囊MSC移行生成EMC和FMC过程，并通过免疫荧光、毛囊重建、细胞移行等多种手段，从分子到动物水平探讨CIV结合DDR1调节MSC移行生成EMC和FMC的机制，为临床白癜风的治疗提供新思路。

人毛囊隆突部黑素干细胞（MSC）是皮肤及毛囊色素细胞的储库，MSC先分化为黑素前体细胞（MP），MP沿毛囊基底膜上行分化为表皮黑素细胞（EMC）为白癜风复色，下行分化为毛母质黑素细胞（FMC）为毛发提供色素。迄今对毛囊基底膜调控MSC移行并生成FMC和EMC的机制不详。既往研究结果提示基底膜主要成分IV型胶原与其配体DDR1（CIV/DDR1）结合可促进MSC移行与分化。在本课题中，我们研究发现：①基底膜成分IV型胶原（Collagen type IV, CIV）/DDR1调控MSC（melanocyte stem cells, MSC）移行并分化生成FMC（follicular matrix melanocytes，FMC ），同时发现CIV可能通过整合素α6等受体调控MSC移行生成FMC；②特异性阻断和激活IV型胶原/DDR1通路对MSC生成FMC的影响验证了CIV/DDR1及相关配体在MSC生成FMC的调控作用；③通过干扰黑素细胞DDR1的表达或阻断黑素细胞DDR1的活化可减低黑素细胞构建有色毛囊能力；④ CIV结合DDR1可调控黑素细胞中的Wnt/β-catenin和TGF-β/Smad2信号通路；⑤不同黑素细胞群及在不同因素干预后的黑素细胞群参与生成有色毛囊能力不同，结果发现TPA和α-MSH作用于黑素细胞后，黑素细胞生成有色毛囊能力下降；⑤研究分别建立过表达DDR1和敲除DDR1的转基因小鼠，但结果显示无论是过表达还是敲除DDR1均未明显影响毛发颜色，在转基因中的这种代偿机制还需进一步研究。整个研究揭示了CIV与DDR1结合调控毛囊中MSC移行生成FMC的机制，结果可能为白癜风和灰发的治疗提供新的思路。