Tissue-specific and developmentally regulated transcription of the insulin-like growth factor 2 gene.

Transcription of the rat and human IGF-2 gene loci is unusually complex. The pattern of expression of these genes varies both between tissues and within a given tissue during different stages of development. Alternative splicing or possibly transcriptional initiation events generate variant IGF-2 mRNAs that contain different 5'-untranslated leader sequences. These leader exon sequences are shared with non-IGF-2 mRNAs. Certain noncoding IGF-2 gene sequence elements are transcribed extensively and are found in multiple copies elsewhere in the human genome. Furthermore, IGF-2 mRNA levels are particularly high in a variety of human malignancies.