Germain L, Fradette J, Robitaille H, Guignard R, Grondin G, Nadeau A, Blouin R
Laboratoire de Recherche des Grands Brûlés/LOEX, CHAUQ Pavillon Saint-Sacrement, Québec, Québec, Canada.
J Invest Dermatol. 2000 Nov;115(5):860-7. doi: 10.1046/j.1523-1747.2000.00024.x.
Leucine-zipper protein kinase/dual leucine zipper bearing kinase/mitogen-activated protein kinase-upstream kinase is a recently described protein serine/threonine kinase which belongs to the mixed lineage kinase family. The overall pattern of expression of the leucine-zipper protein kinase/dual leucine zipper bearing kinase/mitogen-activated protein kinase-upstream kinase gene in embryonic and adult mouse tissues suggested that this kinase could be involved in the regulation of epithelial cell proliferation and differentiation. In order to get more insights into the potential role of leucine-zipper protein kinase in these cellular processes, we characterized its expression in normal human skin, both at the mRNA and protein levels. In situ hybridization, western blotting, and indirect immunofluorescence studies were conducted to localize leucine-zipper protein kinase on various human skin tissues. This is one of the first reports that leucine-zipper protein kinase has a very precise pattern of expression in human skin epithelia, as both mRNA and protein are restricted to the granular layer of the epidermis and inner root sheath of hair follicles. Detection of leucine-zipper protein kinase protein on skin from various body sites, donors of different ages as well as on reconstructed human skin always reveals that leucine-zipper protein kinase is present only in the very differentiated keratinocytes of epidermis and hair follicles. To determine directly whether leucine-zipper protein kinase exhibits any effect on cell growth and differentiation, keratinocytes were transfected with an expression vector harboring the leucine-zipper protein kinase cDNA. The presence of this construct in keratinocytes results in growth arrest together with a concomitant increase in filaggrin expression. Collectively, our results indicate that leucine-zipper protein kinase plays an active part in cellular processes related to terminal differentiation of epidermal keratinocytes.
亮氨酸拉链蛋白激酶/双亮氨酸拉链激酶/丝裂原活化蛋白激酶上游激酶是一种最近被描述的蛋白丝氨酸/苏氨酸激酶，属于混合谱系激酶家族。亮氨酸拉链蛋白激酶/双亮氨酸拉链激酶/丝裂原活化蛋白激酶上游激酶基因在胚胎和成年小鼠组织中的整体表达模式表明，该激酶可能参与上皮细胞增殖和分化的调控。为了更深入了解亮氨酸拉链蛋白激酶在这些细胞过程中的潜在作用，我们在mRNA和蛋白质水平上对其在正常人类皮肤中的表达进行了表征。通过原位杂交、蛋白质印迹和间接免疫荧光研究，在各种人类皮肤组织中定位亮氨酸拉链蛋白激酶。这是首批报道之一，表明亮氨酸拉链蛋白激酶在人类皮肤上皮细胞中具有非常精确的表达模式，因为mRNA和蛋白质都局限于表皮的颗粒层和毛囊的内根鞘。在来自身体不同部位、不同年龄供体的皮肤以及重建的人类皮肤上检测亮氨酸拉链蛋白激酶蛋白，总是发现亮氨酸拉链蛋白激酶仅存在于表皮和毛囊中高度分化的角质形成细胞中。为了直接确定亮氨酸拉链蛋白激酶是否对细胞生长和分化有任何影响，用携带亮氨酸拉链蛋白激酶cDNA的表达载体转染角质形成细胞。该构建体在角质形成细胞中的存在导致生长停滞，并伴随丝聚蛋白表达增加。总的来说，我们的结果表明亮氨酸拉链蛋白激酶在与表皮角质形成细胞终末分化相关的细胞过程中发挥积极作用。
