Adenovirus vectors differentially modulate proliferation of pituitary lactotrophs in primary culture in a mitogen and infection time-dependent manner.
Adenoviruses are powerful, widely utilized vectors for gene transfer. Limitations to their application, however, have not been well described. We used rat pituitary lactotrophs in primary culture as a model for studying how adenovirus vector infection modulates mitogen-induced proliferation and the activities of mitogen signaling pathways. Infection with adenovirus vectors expressing beta-galactosidase (betagal) raised basal proliferative levels and blocked fetal bovine serum (FBS)-induced proliferation of lactotrophs, but did not influence the changes in proliferation induced by forskolin, IGF-I, and bromocriptine. The betagal-expressing adenoviruses did not alter the inhibitory action of 17beta-estradiol (E(2)) in the presence of IGF-I; however, they blocked the stimulatory action of E(2) in the presence of dextran-coated charcoal-striped serum or forskolin. An adenovirus expressing no protein failed to block FBS-induced proliferation, but was effective in modulating basal proliferative levels and the stimulatory actions of E(2). The increased basal proliferative level and the blockade of FBS-induced proliferation were transient, and lost 5 days after infection while the blockade of the stimulatory action of E(2) in the presence of forskolin persisted. Adenovirus infection raised basal protein levels of the phosphorylated forms of cAMP response element-binding protein (pCREB) and ERK1/2 and increased the proportion of pCREB-immunoreactive lactotrophs. Adenoviruses also altered estrogen-induced responses in mRNA expression of several estrogen-responsive genes in a gene-specific manner. The results demonstrate that an adenovirus vector differentially interferes with lactotroph proliferation in response to various mitogens. Our results suggest that the effects of the adenovirus that are independent of the genes transferred must be considered when performing adenoviral gene transfer in the primary cultures of normal cells.
Wang
Zhenhua
Z
Department of Physiology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi 409-3898, Japan.
Mitsui
Tetsuo
T
Ishida
Maho
M
Arita
Jun
J
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D005822:Genetic Vectors / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D052682:Lactotrophs / Q000166:cytology*; D008934:Mitogens / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D013997:Time Factors
D017362:Cyclic AMP Response Element-Binding Protein; D008934:Mitogens; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D048049:Extracellular Signal-Regulated MAP Kinases