Atkinson K J, Rao R K
Department of Pediatrics, Medical University of South Carolina, Charleston, SC 29425, USA.
Am J Physiol Gastrointest Liver Physiol. 2001 Jun;280(6):G1280-8. doi: 10.1152/ajpgi.2001.280.6.G1280.
Acetaldehyde-induced cytotoxicity is an important factor in pathogenesis of alcohol-related diseases; however, the mechanism of this toxicity is unknown. We recently showed that acetaldehyde increases epithelial paracellular permeability. We asked whether protein tyrosine phosphorylation via modulation of tyrosine kinases and/or PTPases is a mechanism involved in acetaldehyde-induced disruption of the tight junctions in the Caco-2 cell monolayer. Immunofluorescence localization of occludin and ZO-1 showed disruption of the tight junctions in acetaldehyde-treated cell monolayer. Administration of genistein prevented acetaldehyde-induced permeability. Acetaldehyde increased tyrosine phosphorylation of three clusters of proteins with molecular masses of 30-50, 60-90, and 110-150 kDa; three of these proteins were ZO-1, E-cadherin, and beta-catenin. Acetaldehyde reduced PTPase activity in plasma membrane and soluble fractions, whereas tyrosine kinase activity remained unaffected. Treatment with acetaldehyde resulted in a 97% loss of protein tyrosine phosphatase (PTP)1B activity and a partial reduction of PTP1C and PTP1D activities. These results strongly suggest that acetaldehyde inhibits PTPases to increase protein tyrosine phosphorylation, which may result in disruption of the tight junctions.
乙醛诱导的细胞毒性是酒精相关疾病发病机制中的一个重要因素；然而，这种毒性的机制尚不清楚。我们最近发现乙醛会增加上皮细胞旁通透性。我们探讨了通过调节酪氨酸激酶和/或蛋白酪氨酸磷酸酶（PTPases）进行的蛋白酪氨酸磷酸化是否是乙醛诱导Caco-2细胞单层紧密连接破坏的一种机制。闭合蛋白和紧密连接蛋白1（ZO-1）的免疫荧光定位显示，经乙醛处理的细胞单层中紧密连接遭到破坏。给予染料木黄酮可防止乙醛诱导的通透性增加。乙醛使分子量分别为30 - 50 kDa、60 - 90 kDa和110 - 150 kDa的三组蛋白的酪氨酸磷酸化增加；其中三种蛋白为ZO-1、E-钙黏蛋白和β-连环蛋白。乙醛降低了质膜和可溶性组分中的PTPase活性，而酪氨酸激酶活性未受影响。用乙醛处理导致蛋白酪氨酸磷酸酶（PTP）1B活性丧失97%，PTP1C和PTP1D活性部分降低。这些结果强烈表明，乙醛通过抑制PTPases来增加蛋白酪氨酸磷酸化，这可能导致紧密连接的破坏。
