Tissue-specific expression of antisense and sense transcripts at the imprinted Gnas locus

Area of Science:

• Genetics
• Molecular Biology
• Epigenetics

Background:

• The Gnas gene encodes the alpha subunit of the stimulatory G protein (G(s)alpha).
• Deficiency in G(s)alpha causes pseudohypoparathyroidism type 1a in humans.
• The Gnas locus exhibits complex transcriptional regulation from three promoters (P1, P2, P3) with distinct imprinting patterns.

Purpose of the Study:

• To investigate the imprinting mechanisms regulating the Gnas locus in mice.
• To identify novel regulatory elements involved in Gnas gene expression.
• To understand the role of antisense transcripts in Gnas imprinting.

Main Methods:

• Analysis of Gnas gene expression in interspecific mouse crosses (Mus spretus x C57BL/6).
• Transcriptional profiling of P1, P2, and P3 promoter-derived transcripts.
• Identification and characterization of antisense transcripts in the Gnas locus.

Main Results:

• Reciprocal imprinting of Gnas transcripts was confirmed in normal mouse tissues.
• P1 transcripts (Nesp55) showed specific abundance in the central nervous system (CNS).
• A novel antisense transcript (Gnas-as) was identified, primarily paternally expressed, and its expression correlated with Nesp55 imprinting.

Conclusions:

• The Gnas gene locus is regulated by complex imprinting mechanisms.
• The newly identified Gnas-as transcript plays a role in regulating Nesp55 transcript imprinting.
• Multiple imprinting elements likely control the allelic expression of Gnas.