Expression of transforming growth factor-beta type II receptor in rat lung is regulated during development.
Transforming growth factor-beta (TGF-beta) is an autocrine/paracrine growth factor that regulates cell proliferation, differentiation, extracellular matrix production and various other cell functions in the lung. TGF-beta exerts its effects on cells by binding to transmembrane heteromeric serine-threonine kinase receptors. The expression and localization of specific TGF-beta receptors in the lung, however, have not yet been investigated. In the present studies, we isolated a 1,762-base pair cDNA containing the full-length coding sequence for TGF-beta type II receptor (T beta RII) from rat fetal lung with the use of polymerase chain reaction methods. The expression of T beta RII during lung development was examined by Northern analysis. A 5.1-kilobase T beta RII mRNA was detected in rat lung tissue. T beta RII mRNA was expressed in rat fetal lung tissue early in development, increased as development proceeded, reached maximal concentration postnatally, and then decreased to the adult level. The localization of T beta RII in fetal and postnatal rat lung tissue was investigated with the use of in situ hybridization performed with an antisense RNA probe. T beta RII gene was expressed in the mesenchymal tissue and in the epithelial lining of the developing airway at day 16 of gestation. The hybridization signal of T beta RII mRNA was also observed in the adventitial layer of small blood vessels. Expression of T beta RII gene in the developing airway epithelium occurred along a proximal-distal gradient. In postnatal lung, T beta RII mRNA was detected mainly in parenchymal tissues and blood vessels. Expression of T beta RII remained high in the interstitium of interalveolar septa.(ABSTRACT TRUNCATED AT 250 WORDS)
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