van Setten G B, Macauley S, Humphreys-Beher M, Chegini N, Schultz G
St. Eriks Eye Clinic, Karolinska Institute, Stockholm, Sweden.
Invest Ophthalmol Vis Sci. 1996 Jan;37(1):166-73.
To assess whether the lacrimal gland is a possible site of synthesis of transforming growth factor-alpha (TGF-alpha) and to characterize TGF-alpha biochemically in human tears.
Reverse transcription-polymerase chain reaction (RT-PCR) amplification was used to analyze rat lacrimal glands for the presence of TGF-alpha mRNA. Specific monoclonal antibodies were used to localize TGF-alpha immunohistochemically in lacrimal gland tissue of rats. Human tears were analyzed for immunoreactive TGF-alpha protein using a specific radioimmunoassay, and the molecular weight of TGF-alpha in tears was characterized by Western blot analysis.
RT-PCR amplification of rat lacrimal gland RNA generated a band of the predicted 492 base pairs for TGF-alpha mRNA. Immunohistochemical staining of rat lacrimal gland localized TGF-alpha protein to lacrymocytes constituting acini but not to interacinar and intraacinar ducts of lacrimal glands. Western blot analysis of human tears detected a single band at MWt 16,000. Logit transformation of radioimmunoassay data for tears and TGF-alpha standard generated parallel displacement lines, indicating the presence of immunoreactive TGF-alpha levels in human tears with an average concentration of 100 +/- 20 pg/ml (mean +/- SEM).
Rat lacrymocytes synthesize TGF-alpha mRNA and protein, and human tears contain immunoreactive TGF-alpha, suggesting that the lacrimal gland may be an exocrine source for TGF-alpha in tears. The single MWt 16,000 form of TGF-alpha in human tears appears to be generated by an unusual proteolytically processing of the pro-TGF-alpha transmembrane precursor protein.
评估泪腺是否可能是转化生长因子-α（TGF-α）的合成部位，并对人泪液中的TGF-α进行生化特性分析。
采用逆转录-聚合酶链反应（RT-PCR）扩增分析大鼠泪腺中TGF-α mRNA的存在情况。使用特异性单克隆抗体通过免疫组织化学方法在大鼠泪腺组织中定位TGF-α。采用特异性放射免疫分析法分析人泪液中的免疫反应性TGF-α蛋白，并通过蛋白质印迹分析确定泪液中TGF-α的分子量。
大鼠泪腺RNA的RT-PCR扩增产生了一条预测的492个碱基对的TGF-α mRNA条带。大鼠泪腺的免疫组织化学染色将TGF-α蛋白定位于构成腺泡的泪腺细胞，而非泪腺的腺泡间导管和腺泡内导管。人泪液的蛋白质印迹分析在分子量16,000处检测到一条单带。泪液和TGF-α标准品的放射免疫分析数据的对数转换产生了平行的位移线，表明人泪液中存在免疫反应性TGF-α水平，平均浓度为100±20 pg/ml（平均值±标准误）。
大鼠泪腺细胞合成TGF-α mRNA和蛋白，人泪液中含有免疫反应性TGF-α，提示泪腺可能是泪液中TGF-α的外分泌来源。人泪液中单一分子量16,000形式的TGF-α似乎是由前体TGF-α跨膜前体蛋白经过异常的蛋白水解加工产生的。
