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- Author: Zhenhua Wang x
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Department of Physiology, Department of Physiology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi 409-3898, Japan
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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 β-galactosidase (βgal) 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 βgal-expressing adenoviruses did not alter the inhibitory action of 17β-estradiol (E2) in the presence of IGF-I; however, they blocked the stimulatory action of E2 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 E2. 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 E2 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.
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Apoptosis plays a critical role in the diabetic cardiomyopathy, and endoplasmic reticulum stress (ERS) is one of the intrinsic apoptosis pathways. Previous studies have shown that the endoplasmic reticulum becomes swollen and dilated in diabetic myocardium, and ERS is involved in heart failure and diabetic kidney. This study is aimed to demonstrate whether ERS is induced in myocardium of streptozotocin (STZ)-induced diabetic rats. We established a type 1 diabetic rat model, used echocardiographic evaluation, hematoxylin–eosin staining, and the terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling staining to identify the existence of diabetic cardiomyopathy and enhanced apoptosis in the diabetic heart. We performed immunohistochemistry, western blot, and real-time PCR to analyze the hallmarks of ERS that include glucose-regulated protein 78, CCAAT/enhancer-binding protein homologous protein (CHOP) and caspase12. We found these hallmarks to have enhanced expression in protein and mRNA levels in diabetic myocardium. Also, another pathway that can lead to cell death of ERS, c-Jun NH2-terminal kinase-dependent pathway, was also activated in diabetic heart. Those results suggested that ERS was induced in STZ-induced diabetic rats' myocardium, and ERS-associated apoptosis occurred in the pathophysiology of diabetic cardiomyopathy.
