Premium
Isolation of a cDNA encoding a growth‐arrest associated gene and characterization of its regulation
Author(s) -
Ge Lynn,
Liau Gene
Publication year - 1995
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240570217
Subject(s) - complementary dna , microbiology and biotechnology , biology , messenger rna , cdna library , gene , gene expression , northern blot , southern blot , cell cycle , genomic dna , cell growth , genetics
We are interested in understanding the molecular events associated with the growth‐arrest of vascular SMCs. We constructed a subtracted cDNA library enriched in nucleotide sequences associated with quiescent SMCs. This library was screened with similarly subtracted 32 P‐labeled cDNAs to identify growth‐arrest associated cDNA clones. Characterization of 19 of these cDNA clones revealed that 9 hybridized to mRNAs that exhibited a 2–3 fold increase in growth‐arrested SMCs. In addition, two other cDNAs hybridized to a 5 Kb mRNA that was elevated approximately 10‐fold in high density growth‐arrested SMCs. Genomic Southern blot hybridization and DNA sequencing analysis indicated that these cDNAs encoded the same gene (LG7) and that this gene may be a member of a multigene family or that it may contain a sequence shared by other unrelated genes. Augmented expression of LG7 was associated with both high cell density and serum deprivation induced growth‐arrest. LG7 mRNA expression was down‐regulated when SMCs were incubated with FBS or with reagents that arrest cells in early S‐phase. Additional analysis with cell cycle specific inhibitors indicated that LG7 mRNA levels were also low when cells were blocked at the G 2 phase of the cell cycle but blockage at mitosis resulted in an elevated level of LG7 mRNA. We further demonstrated that the expression of LG7 was dependent on the presence of a relatively labile protein since protein synthesis inhibitors specifically blocked the expression of this mRNA but not the mRNA expression of α 1 (III) collagen or ferritin H‐chain. Finally, we demonstrated that Bt 2 cAMP was able to induce mRNA expression of LG7 within 2 h, suggesting that this gene may be directly regulated via the cyclic‐AMP‐dependent protein kinase pathway.