Cell-specific expression of the alpha 1 (I) collagen promoter-CAT transgene in skin and lung: a response to TGF-beta subcutaneous injection and bleomycin endotracheal instillation.
Transgenic mice containing a rat collagen alpha 1 (I) promoter (3.6 kilobases) fused to the reporter gene chloramphenicol acetyl transferase (CAT) express the reporter gene parallel to endogenous gene in most connective tissues other than vascular tissue [Pavlin et al. (1992): J Cell Biol 116:227-236; Bedalov et al. (1994): J Biol Chem 269:4903-4909]. We have challenged transgenic mice with subcutaneous injections of transforming growth factor-beta (TGF-beta) or intratracheal instillation of bleomycin. In situ hybridization studies of skin revealed increased CAT expression in the papillary dermis of TGF-beta treated animals. In contrast, alpha 1 (I) collagen mRNA was expressed throughout the dermis including granulation tissue and reticular dermis. Therefore, the transgenic promoter responds to TGF-beta in a subset of dermal fibroblasts. Endotracheal instillation of bleomycin induces lung fibrosis which is thought to be mediated in part by TGF-beta. CAT gene expression in lungs was increased 6-8-fold at 2 weeks post bleomycin treatment. In situ hybridization studies revealed focal areas of cells expressing both CAT and collagen genes in the interstitium. However, most regions, especially around airways, contained a subset of cells expressing the endogenous gene with little or no CAT expression as judged by in situ hybridization. These cells could be myofibroblasts that require additional cis-acting elements to activate alpha 1 (I) collagen gene expression similar to smooth muscle cells.
Agarwal
A R
AR
Department of Biochemistry, Boston University Medical Center, MA 02118, USA.
Goldstein
R H
RH
Lucey
E
E
Ngo
H Q
HQ
Smith
B D
BD
D000818:Animals; D001761:Bleomycin / Q000008:administration & dosage / Q000494:pharmacology*; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003094:Collagen / Q000235:genetics*; D017930:Genes, Reporter; D017403:In Situ Hybridization; D007279:Injections, Subcutaneous; D007442:Intubation, Intratracheal; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000008:administration & dosage / Q000494:pharmacology*
D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D001761:Bleomycin; D003094:Collagen; D015500:Chloramphenicol O-Acetyltransferase