Universite Lyon 1, EA4169-Laboratory of Dermatology, Edouard Herriot Hospital, Lyon, France.
J Physiol Pharmacol. 2009 Oct;60 Suppl 4:23-30.
Integrity of the skin is necessary for maintaining body's homeostasis. Barrier function of human skin largely depends on the final product of epidermal cell differentiation, the horny layer, i.e. stratum corneum. As epidermis is constantly in self-renewal, the superficial desquamation is adequately compensated by keratinocyte proliferation in epidermal basal layer. Cohesion in the epidermis depends on the presence of specialized adhering junctions, desmosomes, and their modified version encountered in the horny layer, corneodesmosomes. These structures must be finely regulated to allow a regular flow of differentiating keratinocytes through the epidermal layers and their release at the top of the skin, without compromising tissue resilience and cohesion. Extracellular matrix (ECM) molecules, which fill the inter-keratinocyte spaces in living epidermal layers, are involved in tissue hydration, nutrition, and regulation of cell proliferation and differentiation. In the stratum corneum, extracellular lipids self-organize into multilayered sheets, essential for establishing of the permeability barrier. Desmosealin is a new epidermal proteoglycan, part of the tissue-specific ECM, that shows affinity to the extracellular compartment of desmosomes. This highly glycosylated molecule may play a role in the protection of desmosomes against premature proteolysis of its components, and, thus, in the skin barrier function.
皮肤的完整性对于维持身体的内稳态至关重要。人体皮肤的屏障功能在很大程度上取决于表皮细胞分化的最终产物——角质层，即角质层。由于表皮不断自我更新，表皮基底层角质形成细胞的增殖足以充分补偿表面的脱屑。表皮的黏附取决于专门的黏附连接、桥粒，以及在角质层中遇到的其变体桥粒芯糖蛋白。为了允许分化的角质形成细胞有规律地通过表皮层并在皮肤顶部释放，而不损害组织弹性和黏附性，这些结构必须得到精细的调节。细胞外基质 (ECM) 分子填充活表皮层的细胞间空间，参与组织水合、营养以及细胞增殖和分化的调节。在角质层中，细胞外脂质自组织成多层片层，这对于建立通透性屏障是必不可少的。桥粒芯糖蛋白是一种新型的表皮蛋白聚糖，是组织特异性 ECM 的一部分，对桥粒的细胞外隔室具有亲和力。这种高度糖基化的分子可能在保护桥粒免受其成分过早蛋白水解方面发挥作用，从而影响皮肤屏障功能。
