改变黑素小体腔内pH值影响表皮黑素细胞的黑素生成

Regulation of Melanogenesis in Epidermal Melanocytes Through Controlling the Intramelanosomal pH

黑素小体是一种真核生物细胞中高度特化的用于合成与贮存黑素的细胞器。它最早起源于溶酶体衍生小囊泡,为单层质膜包裹的近似封闭的酸性细胞器,其腔内环境的pH值大约是4～5。位于黑素小体膜上的酪氨酸酶,被认为是黑素合成的主要限速酶,它的最适pH值为6.8,这就意味着在酸性黑素小体内酪氨酸酶处于未活化状态。有研究表明,黑素小体膜上存在有多种不同类型的离子通道和质子泵,协同参与调节和维持着黑素小体腔内的偏酸环境。改变黑素小体腔内pH值可直接影响黑素细胞的黑素合成,为临床治疗色素异常相关疾病以及皮肤美白产品的研发提供了一个新途径。

The melanosome is a highly specialized organelle in eukaryotic cells,which serves as the site for synthesis and storage of melanin. Melanosomes are originated from lysosomal vesicles and encapsulated by monolayer plasma membrane to form acidic and almost closed compartments,in which pH is approximately 4~5. Tyrosinase,a key rate-limiting enzyme in the melanin synthesis,is localized to the membrane of melanosomes and its optimal pH is 6.8,that means this membrane-bound enzyme is largely inactive in the acidic melanosomes. It is well established that there are many ion channels and transporters in the melanosomal membrane to regulate or maintain this slightly acidic intraluminal pH. Change of the melanogenesis in epidermal melanocytes through controlling the intramelanosomal pH paves a way for treatment of pigmentary disorders and for development of skin-lightening cosmetic products.