Quan Taihao, He Tianyuan, Kang Sewon, Voorhees John J, Fisher Gary J
Department of Dermatology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0609, USA.
J Invest Dermatol. 2002 Mar;118(3):402-8. doi: 10.1046/j.0022-202x.2001.01678.x.
Connective tissue growth factor, which is induced by transforming growth factor beta, has been reported to mediate the stimulatory actions of transforming growth factor beta on type I procollagen synthesis. Connective tissue growth factor is expressed in fibrotic disease such as scleroderma, where it is believed to promote abnormal deposition of collagen. Connective tissue growth factor expression has not been described in normal human skin or cultured skin cells, however. We report here that connective tissue growth factor mRNA is constitutively expressed in normal human skin. In situ hybridization demonstrated that connective tissue growth factor mRNA was expressed in keratinocytes throughout the epidermis and in dermal cells. Quantitative real-time reverse transcription polymerase chain reaction revealed that the level of connective tissue growth factor mRNA in the epidermis and dermis of normal human skin was comparable to the level of housekeeping gene 36B4. Ultraviolet irradiation (2 minimal erythema dose, UVB/A2 source) reduced connective tissue growth factor mRNA expression throughout the epidermis and dermis in normal human skin in vivo. Connective tissue growth factor mRNA was reduced (30%) within 4 h post ultraviolet irradiation, and remained reduced (50%) 8-24 h post ultraviolet. Connective tissue growth factor mRNA and protein were also constitutively highly expressed in normal cultured human skin keratinocytes and fibroblasts. Ultraviolet irradiation of cultured normal human skin fibroblasts resulted in a time-dependent inhibition of connective tissue growth factor mRNA expression. At 24 h post ultraviolet, connective tissue growth factor mRNA expression was reduced 80%. Transforming growth factor beta1 rapidly induced connective tissue growth factor mRNA levels (5-fold within 4 h) in skin fibroblasts, but not keratinocytes, and this induction was attenuated 80% by ultraviolet irradiation. Electrophoretic mobility shift assays demonstrated that ultraviolet irradiation reduced protein binding to the transforming growth factor beta/Smad responsiveness elements in the connective tissue growth factor gene promoter, in human skin in vivo and human skin fibroblasts. Constitutive expression of connective tissue growth factor in normal human skin suggests that it is a physiologic regulator of procollagen synthesis. Ultraviolet reduction of connective tissue growth factor expression may contribute to reduced procollagen synthesis observed in ultraviolet-irradiated normal human skin and human skin fibroblasts.
结缔组织生长因子由转化生长因子β诱导产生，据报道它介导转化生长因子β对I型前胶原合成的刺激作用。结缔组织生长因子在诸如硬皮病等纤维化疾病中表达，据信它在其中促进胶原蛋白的异常沉积。然而，在正常人类皮肤或培养的皮肤细胞中尚未描述结缔组织生长因子的表达情况。我们在此报告，结缔组织生长因子mRNA在正常人类皮肤中组成性表达。原位杂交表明，结缔组织生长因子mRNA在整个表皮的角质形成细胞和真皮细胞中表达。定量实时逆转录聚合酶链反应显示，正常人类皮肤表皮和真皮中结缔组织生长因子mRNA的水平与看家基因36B4的水平相当。紫外线照射（2个最小红斑量，UVB/A2光源）可降低正常人类皮肤体内整个表皮和真皮中结缔组织生长因子mRNA的表达。紫外线照射后4小时内，结缔组织生长因子mRNA减少（30%），紫外线照射后8 - 24小时仍减少（50%）。结缔组织生长因子mRNA和蛋白在正常培养的人类皮肤角质形成细胞和成纤维细胞中也组成性高表达。对培养的正常人类皮肤成纤维细胞进行紫外线照射导致结缔组织生长因子mRNA表达呈时间依赖性抑制。紫外线照射后24小时，结缔组织生长因子mRNA表达减少80%。转化生长因子β1可迅速诱导皮肤成纤维细胞中结缔组织生长因子mRNA水平（4小时内增加5倍），但不能诱导角质形成细胞中的该水平，并且这种诱导作用在紫外线照射后减弱80%。电泳迁移率变动分析表明，紫外线照射可降低体内人类皮肤和人类皮肤成纤维细胞中结缔组织生长因子基因启动子上与转化生长因子β/Smad反应元件的蛋白结合。结缔组织生长因子在正常人类皮肤中的组成性表达表明它是前胶原合成的生理调节因子。紫外线降低结缔组织生长因子的表达可能有助于减少在紫外线照射的正常人类皮肤和人类皮肤成纤维细胞中观察到的前胶原合成。
