Regulation of insulin‐like‐growth‐factor‐II gene expression in rat liver cells

Abstract

The rat insulin-like-growth-factor-(1GF)-I1 gene is expressed at high levels during embryonic and fetal life and at low levels in adult animals. To study the regulation of IGF-I1 gene expression, we analyzed the synthesis and localization of the IGF-I1 transcripts in cultured rat liver cells either expressing (BRL3A cells) or not expressing (BRL30E and F A 0 cells) the IGF-I1 mRNA. The IGF-I1 gene is transcribed at a similar rate in expressing and non-expressing cells, whereas its nuclear and cytoplasmic RNA levels are diversely distributed in the cells. IGF-I1 RNA is more abundant in the cytoplasmic than in the nuclear RNA fraction of BRL3A cells and is present in the nucleus but not in the cytoplasm of the F A 0 cells. However, both precursor and mature IGF-I1 nuclear RNA levels are reduced in FA0 cells. Our data indicate that the IGF-I1 gene expression is regulated by mechanisms affecting the subcellular distribution and the abundance of the transcripts.

Differential expression of SNAP-25a and SNAP-25b RNA transcripts in cranial nerve nuclei

“…When studying EGF receptor RNA in A431 epidermoid carcinoma cells, exon sequences were localized to two sites around the nucleolus, only one of which overlapped the intron sequences (Sibon et al, 1996). There also may be an increased destabilization and degradation of cytoplasmic mRNA (Zarrilli et al, 1992;Sachs, 1993;Beelman and Parker, 1995). Whether mature SNAP-25a protein is formed is not clear, although high levels of mature EGF receptor protein have been found in A431 cells expressing nuclear EGF receptor RNA transcripts (Wrann and Fox, 1979;Sibon et al, 1993).…”

Cardiomyoblast apoptosis induced by insulin-like growth factor (IGF)-I resistance is IGF-II dependent and synergistically enhanced by angiotensin II

“…1). We observed a synergistic effect rather than additive effect on DNA fragmentation with the combination of Ang II (10 −8 M) and IGF-IR antibody (20,40, and 60 ng/ml) Fig. 4 (a) The IGF-II and IGF-IIR protein products were induced by antisense IGF-I, IGF-IR antibody or IGF-I antibody.…”

“…DNA ladder formation revealed that cardiac H9c2 cell underwent DNA fragmentation when exposed to either Ang II (10 −8 M) or IGF-IR antibody (20,40, and 60 ng/ml), compared to the negative and positive controls (Fig. 1).…”

“…To clarify whether cardiomyoblast apoptosis was induced by Ang II and/or IGF-IR antibody, DNA fragmentations were measured with or without administration of Ang II (10 −8 M) and/or IGF-I receptor antibody (20,40, 60 ng/ml). DNA ladder formation revealed that cardiac H9c2 cell underwent DNA fragmentation when exposed to either Ang II (10 −8 M) or IGF-IR antibody (20,40, and 60 ng/ml), compared to the negative and positive controls (Fig.…”

Long-Range RNA Interaction of Two Sequence Elements Required for Endonucleolytic Cleavage of Human Insulin-Like Growth Factor II mRNAs

“…The human and mouse IGF-II genes are also subject to genomic imprinting (12,26,31). In addition, regulation takes place at the levels of translation (25) and mRNA stability (21,27,48).…”