Imprinting of IGF2 P0 transcript and novel alternatively spliced INS-IGF2 isoforms show differences between mouse and...

Area of Science:

• Genetics
• Molecular Biology
• Developmental Biology

Background:

• Genomic imprinting regulates genes crucial for fetal growth, development, and behavior.
• Aberrant imprinting of insulin-like growth factor 2 (IGF2) is linked to growth disorders and cancers.
• Specific IGF2 isoforms are vital for placental function, as demonstrated in mouse models.

Purpose of the Study:

• To identify and characterize novel human transcripts originating from the IGF2 locus.
• To elucidate the molecular mechanisms, including allele-specific expression and methylation, governing the imprinting of these new transcripts.
• To investigate the tissue-specific expression patterns and regulatory mechanisms of IGF2 and its novel transcripts.

Main Methods:

• Identification of novel human IGF2 transcripts, including IGF2-P0 and INSIGF (long and short) variants.
• Analysis of allele-specific expression across various human tissues.
• Assessment of DNA methylation patterns at IGF2 promoters, including P0 and those for INSIGF transcripts.

Main Results:

• The human IGF2-P0 transcript is paternally expressed, with expression not confined to the placenta, and shows tissue-specific maternal allele methylation.
• Two novel INSIGF transcripts utilize the INS promoter, exhibiting restricted tissue expression, notably in the pancreas.
• Complex, tissue-specific imprinting was demonstrated for these novel transcripts, similar to previously reported INS imprinting in the yolk sac.

Conclusions:

• The discovery of additional IGF2 transcripts expands our understanding of this gene's complex regulatory network.
• These findings have significant implications for understanding IGF2's role in human development, metabolism, and disease, particularly in cancer.
• Further research into these novel transcripts is warranted to fully elucidate their functional significance and regulatory pathways.