Borok Z, Danto S I, Lubman R L, Cao Y, Williams M C, Crandall E D
Will Rogers Institute Pulmonary Research Center, Division of Pulmonary and Critical Care Medicine, University of Southern California, Los Angeles, California 90033, USA.
Am J Physiol. 1998 Jul;275(1):L155-64. doi: 10.1152/ajplung.1998.275.1.L155.
T1alpha is a recently identified gene expressed in the adult rat lung by alveolar type I (AT1) epithelial cells but not by alveolar type II (AT2) epithelial cells. We evaluated the effects of modulating alveolar epithelial cell (AEC) phenotype in vitro on T1alpha expression using either soluble factors or changes in cell shape to influence phenotype. For studies on the effects of soluble factors on T1alpha expression, rat AT2 cells were grown on polycarbonate filters in serum-free medium (MDSF) or in MDSF supplemented with either bovine serum (BS, 10%), rat serum (RS, 5%), or keratinocyte growth factor (KGF, 10 ng/ml) from either day 0 or day 4 through day 8 in culture. For studies on the effects of cell shape on T1alpha expression, AT2 cells were plated on thick collagen gels in MDSF supplemented with BS. Gels were detached on either day 1 (DG1) or day 4 (DG4) or were left attached until day 8. RNA and protein were harvested at intervals between days 1 and 8 in culture, and T1alpha expression was quantified by Northern and Western blotting, respectively. Expression of T1alpha progressively increases in AEC grown in MDSF +/- BS between day 1 and day 8 in culture, consistent with transition toward an AT1 cell phenotype. Exposure to RS or KGF from day 0 prevents the increase in T1alpha expression on day 8, whereas addition of either factor from day 4 through day 8 reverses the increase. AEC cultured on attached gels express high levels of T1alpha on days 4 and 8. T1alpha expression is markedly inhibited in both DG1 and DG4 cultures, consistent with both inhibition and reversal of the transition toward the AT1 cell phenotype. These results demonstrate that both soluble factors and alterations in cell shape modulate T1alpha expression in parallel with AEC phenotype and provide further support for the concept that transdifferentiation between AT2 and AT1 cell phenotypes is at least partially reversible.
T1α是最近发现的一个基因，在成年大鼠肺中由I型肺泡（AT1）上皮细胞表达，而II型肺泡（AT2）上皮细胞不表达。我们使用可溶性因子或细胞形状变化来影响表型，从而在体外评估调节肺泡上皮细胞（AEC）表型对T1α表达的影响。为了研究可溶性因子对T1α表达的影响，大鼠AT2细胞在无血清培养基（MDSF）中的聚碳酸酯滤膜上生长，或在从培养第0天或第4天到第8天添加牛血清（BS，10%）、大鼠血清（RS，5%）或角质形成细胞生长因子（KGF，10 ng/ml）的MDSF中生长。为了研究细胞形状对T1α表达的影响，将AT2细胞接种在添加了BS的MDSF中的厚胶原凝胶上。凝胶在第1天（DG1）或第4天（DG4）分离，或一直附着到第8天。在培养的第1天到第8天期间定期收集RNA和蛋白质，分别通过Northern印迹和Western印迹对T1α表达进行定量。在培养第1天到第8天期间，在MDSF±BS中生长的AEC中，T1α表达逐渐增加，这与向AT1细胞表型的转变一致。从第0天开始暴露于RS或KGF可阻止第8天T1α表达的增加，而从第4天到第8天添加任何一种因子均可逆转这种增加。在附着凝胶上培养的AEC在第4天和第8天表达高水平的T1α。在DG1和DG4培养物中，T1α表达均受到明显抑制这与向AT1细胞表型转变的抑制和逆转均一致。这些结果表明，可溶性因子和细胞形状改变均与AEC表型平行调节T1α表达，并为AT2和AT1细胞表型之间的转分化至少部分可逆这一概念提供了进一步支持。
