Developmental and tissue-specific expression of a family of transcripts related to rat insulin-like growth factor II mRNA

Abstract

We have constructed a cDNA library from the mRNA of a rat liver cell line (BRL-3A) and characterized cDNA clones encoding the protein precursor of the rat insulin-like growth factor II (pre-pro-rIGF-II). This precursor, inferred from the nucleotide sequence, consists of a signal peptide, the rIGF-II sequence, and a trailer polypeptide of unknown significance. The characterized cDNA sequence (1016 nt) is part of a 3.4 kb mRNA species. Northern analysis reveals that a probe containing the extreme 5' noncoding region hybridizes to a second RNA (1.6 kb), while a probe corresponding to the 5' noncoding region proximal to the coding region hybridizes to two other RNA species (1.75 and 1.1 kb). All four RNAs are differentially expressed in all of the neonatal tissues that were examined, while the 3.4 kb pre-pro-rIGF-II mRNA and the 1.1 kb transcript are absent from adult tissues.

Expression of insulin‐like growth factor‐I and ‐II genes in rat medullary thyroid carcinoma

“…As described by others, IGF-II RNA can easily be detected in a variety of fetal and neonatal rat and human tissues, but can hardly be detected in adult rat, mouse and human liver [20,25], even though the liver is considered to be one of the major sites of IGF-II production in adult organisms [25]. IGF-II RNA was undetectable in adult rat liver in our experiments.…”

“…On the other hand, it might point to the existence of related but as yet unknown rat IGF-II genes. In this respect it is important to note that both developmental and tissue-specific expression of several rat pre-pro-IGF-II related transcripts have been reported [20].…”

Thymic expression of insulin-related genes in an animal model of autoimmune type 1 diabetes

“…The molecular mechanisms responsible for the defect of Igf2 expression in the thymus of BBDP rats remain to be determined. Rat Igf2 contains six exons, is transcribed from three distinct promoters (P1, P2 and P3), and is expressed in a tissue-specific and developmentally regulated manner [29][30][31][32]. In the rat fetus, Igf1 and Igf2 are expressed in different tissues with a marked predominance of Igf2 [33][34][35].…”

Mechanisms of HBx Mediated Liver Cancer: Multiple Pathways and Opportunities

“…The finding that insulin-like growth factor-2 expression, which is normally observed only in fetal liver (Soares et al, 1985), is elevated in HCCs (D'Arville et al, 1991, Cariani et al, 1991, and in premalignant proliferative nodules in the liver (Cariani et al, 1988;D'Arville et al, 1991), suggest that its reactivation may be an early step in the development of this tumor type. The elevation of IGF-2 expression in HCCs from HBV infected but not uninfected patients, combined with the finding of a strong correlation between IGF-2 and HBx in the liver by immunohistochemical staining (Su et al, 1994), suggest that IGF-2 may be a natural target of HBx during chronic infection.…”