N. Akiyama et al., Identification of a series of transforming growth factor beta-responsive genes by retrovirus-mediated gene trap screening, MOL CELL B, 20(9), 2000, pp. 3266-3273
Transforming growth factor beta (TGF-beta) plays important roles in the reg
ulation of proliferation, differentiation! apoptosis, and carcinogenesis. T
o identify genes responsible for maintaining the phenotype induced by TGF-b
eta, we performed a retrovirus-mediated gene trap screening designed to iso
late TGF-beta-responsive genes in human lung carcinoma cell line A549. Afte
r screening 249 trap lines, 21 were found to express the reporter beta-gala
ctosidase gene in a TGF-beta-responsive manner. Interestingly, in large pro
portions of these trap lines, the reporter gene uas responsive also to phor
bol ester and was suppressed by gamma interferon, Fragments of all these tr
apped genes were recovered by 5'- and 3'-rapid amplification of cDNA ends (
RACE), and in 15 out of 21 cases (71%), the TGF-beta responsiveness of the
endogenous genes H-as confirmed by RNA blot hybridization. In at least five
cases, the TGF-beta-induced upregulation was found to be cycloheximide res
istant, suggesting the roles of the genes in the TGF-beta-induced primary r
esponses. Sequence analyses revealed that 43% (9 of 21) of the trapped gene
s were novel and that the remainder included genes previously reported to b
e upregulated by TGF-beta, such as epidermal growth factor receptor and bet
a 1 integrin, documenting the validity of this approach, Other known genes
include the ones encoding the proteins associated with cell proliferation (
ribosomal proteins S15a, hNRP/NAP-1, and lipocortin II), focal adhesions (p
axillin), and transcriptional regulation (thyroid hormone receptor activato
r molecule 1 [TRAM-1]).