The structural H19 gene is required for transgene imprinting

Area of Science:

• Genetics
• Epigenetics
• Developmental Biology

Background:

• The H19 gene produces untranslated RNA essential for mammalian development.
• H19 and its 5'-flanking sequence regulate genomic imprinting of nearby genes like Ins-2 and Igf-2.

Purpose of the Study:

• Investigate the H19 gene's role in its own genomic imprinting.
• Determine the sequences required for H19 imprinting and its cis-acting function.

Main Methods:

• Introduction of a Mus spretus H19 gene transgene into the mouse genome.
• Modification of the H19 transgene by replacing the structural gene or deleting 5' sequences.
• Analysis of transgene imprinting, DNA methylation, and expression patterns.
• Assessment of the H19 transgene's ability to rescue imprinting in H19 deletion mice.

Main Results:

• Multiple copies of the H19 transgene achieved paternal silencing and DNA methylation.
• Replacing the H19 gene with a reporter abolished imprinting, indicating the gene product is necessary.
• Deletion of 5' sequences disrupted paternal-specific DNA methylation, highlighting their importance.
• The H19 transgene could not rescue Igf-2 imprinting in trans, confirming a cis requirement.

Conclusions:

• Specific sequences within the H19 gene are crucial for establishing and maintaining its imprinting.
• The H19 gene functions in cis to regulate its own imprinting.
• A previously reported prenatal lethality was attributed to a neomorphic mutation in a marked H19 gene, not H19 overexpression itself.