Molecular cloning of gene sequences regulated during squamous differentiation of tracheal epithelial cells and controlled by retinoic acid.

Abstract

A cDNA library was constructed from polyadenylated RNA present in squamous differentiated rabbit tracheal epithelial cells. Screening of the cDNA library was aimed at identifying RNAs that were abundant in squamous cells and expressed at low levels in undifferentiated cells. Two different recombinants were obtained containing inserts, 0.86 and 0.77 kilobases (kb) in size, that hybridized to mRNAs 1.0 and 1.25 kb in length. These RNAs were present at approximately 50-fold higher levels in squamous cells than in proliferative or confluent retinoic acid-treated cells. The increase in the levels of the 1.0-and 1.25-kb RNAs correlated closely with the onset of squamous difrerentiation and was not related to induction of terminal cell division. Treatment of rabbit tracheal epithelial cells with transforming growth factor IS, which induces squamous differentiation in these cells, also resulted in elevated levels of the 1.0-and 1.25-kb RNAs. The increased levels of these RNAs in squamous cells appeared to a large extent to be regulated at a posttranscriptional level. Retinoic acid not only inhibited the increase in the levels of the 1.0-and 1.25-kb RNAs but also reversed the expression of these RNAs in squiamous ceUs. These results suggest that retinoic acid affects, directly or indirectly, molecular events that induce alterations in the posttranscriptional processing of the transcripts corresponding to the 1.0-and 1.25-kb RNAs.

Control of growth and squamous differentiation in normal human bronchial epithelial cells by chemical and biological modifiers and transferred genes.

“…The data implied that TGF-p1 is an important differentiationinducing serum factor in NHBE cells. Similar findings have been reported for rat hepatocytes (44), mouse or human epiderminal keratinocytes (24,45), and rabbit tracheal epithelial cells (46,47).…”

Molecular biology of keratinocyte differentiation.

“…Retinoids have been known since the early 20th century to profoundly affect epithelial cell organization (20), and many different cell types are developmentally regulated by retinoids (17,(21)(22)(23)(24)(25)(26)(27)(28). Retinoid treatment of human keratinocytes in culture drastically changes the morphology of these cells.…”

Regulation of type I (epidermal) transglutaminase mRNA levels during squamous differentiation: down regulation by retinoids.

“…DNA blots were hybridized to nick-translated probes (2 x 108 to 4 x 108 cpm/,ug) essentially as described elsewhere (33). Alternatively, DNA blots were hybridized to the 32P-labeled mixed-oligonucleotide probe essentially as described above for plaque hybridizations.…”