Zbytek Blazej, Slominski Andrzej T
Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
J Cell Physiol. 2005 Apr;203(1):118-26. doi: 10.1002/jcp.20209.
Previously we documented that human epidermis exclusively expresses corticotropin releasing hormone receptor 1 (CRH-R1). To define the role of CRH in the epidermis, we investigated its effects on differentiation of normal human adult epidermal keratinocytes. Thus, CRH inhibited proliferation in a dose dependent fashion and significantly decreased Ki-67 antigen expression. This effect was independent of either the presence or the absence of growth factors in the medium. Flow cytometry analysis demonstrated that CRH inhibited the transition from G0/1 to S phase of the cell cycle, which was accompanied by an increased expression of cdk inhibitor p16 (Ink4a) protein. The antiproliferative effect was attenuated by protein kinase C inhibitor (GF109203X) but not by H89 (protein kinase A inhibitor), PD98059, or SB203580 (MAP kinase inhibitors). The cell cycle withdrawal was associated with the induction of keratinocyte differentiation. Thus, CRH stimulated the expression of cytokeratin 1 and involucrin, and inhibited cytokeratin 14 on both mRNA and protein levels. It also increased cell granularity and cell size. Furthermore, CRH induced signal transduction cascade that included stimulation of inositol 1,4,5-triphosphate, which was time and dose dependent. CRH also increased activator protein-1 DNA binding activity with JunD identified as the most important element. Thus, activation of CRH-R1 induces a non-random and sequential signal transduction cascade governing both keratinocyte differentiation and the inhibition of cell proliferation through G0/1 arrest. We propose that this program, triggered by CRH interaction with CRH-R1, includes induction of a transduction pathway involving the sequential activation of phospholipase C, protein kinase C, activator protein-1 (including Jun D), and p16.
此前我们记录到人类表皮仅表达促肾上腺皮质激素释放激素受体1（CRH-R1）。为了明确CRH在表皮中的作用，我们研究了其对正常成人人类表皮角质形成细胞分化的影响。因此，CRH以剂量依赖性方式抑制增殖，并显著降低Ki-67抗原表达。这种效应与培养基中生长因子的存在与否无关。流式细胞术分析表明，CRH抑制细胞周期从G0/1期向S期的转变，同时伴有细胞周期蛋白依赖性激酶抑制剂p16（Ink4a）蛋白表达增加。蛋白激酶C抑制剂（GF109203X）可减弱这种抗增殖作用，但蛋白激酶A抑制剂H89、PD98059或丝裂原活化蛋白激酶抑制剂SB203580则无此作用。细胞周期停滞与角质形成细胞分化的诱导相关。因此，CRH在mRNA和蛋白水平上均刺激细胞角蛋白1和兜甲蛋白的表达，并抑制细胞角蛋白14的表达。它还增加了细胞颗粒度和细胞大小。此外，CRH诱导了信号转导级联反应，包括对1,4,5-三磷酸肌醇的刺激，这具有时间和剂量依赖性。CRH还增加了活化蛋白-1的DNA结合活性，其中JunD被确定为最重要的元件。因此，CRH-R1的激活诱导了一个非随机且有序的信号转导级联反应，通过G0/1期停滞来控制角质形成细胞的分化和细胞增殖的抑制。我们提出，由CRH与CRH-R1相互作用触发的这个程序包括诱导一条涉及磷脂酶C、蛋白激酶C、活化蛋白-1（包括Jun D）和p16顺序激活的转导途径。
