Imprinting analysis of three genes in the Prader — Willi/Angelman region: SNRPN, E6-associated protein, and PAR-2 (D15S225E)

Abstract

In order to Identify genes In the Prader—WiIIi/Angelman syndrome critical region, radlolabeled cDNA probes from poly(A)⁺ RNA from mouse tissues were used to identify potential exon-contalning genomic DNA fragments in cosmid or phage clones from appropriate yeast artificial chromosomes, and these fragments were subsequently used to screen human cDNA libraries. A mouse brain cDNA probe was effective in detecting control genes of various abundance including small nuclear ribonucleoproteln polypeptide N (SNRPN), hypoxanthlne-guanine phosphoribosyl transferase, glyceraldehyde-3-phosphate dehydrogenase, and β-actln. Two genes mapping within the Angelman syndrome critical region were Isolated. One gene was found to encode the E6-associated protein (E6-AP; gene symbol HPVE6A), a protein which Interacts with the E6 protein of human papilloma virus. The other gene is previously uncharacterized and Is designated PAR-2 (D15S225E) for Prader — Willi and Angelman region-gene 2. Imprinting analysis using reverse transcription-polymerase chain reaction of RNA from flbroblasts and lymphoblasts of deletion Prader— Willl and Angelman patients demonstrated imprinting of SNRPN with exclusive expression from the paternal allele, but E6-AP and PAR-2 were not Imprinted in these cultured human cells. The ability to analyze for Imprinting and expression of SNRPN and other genes In this region In cultured human cells will be a valuable tool for analyzing the molecular basis of the Prader — Willl and Angelman syndromes, although imprinting may differ between cultured cells and tissues. Based on the biological information for E6-AP and on the imprinting analysis of E6-AP and PAR-2, neither of these genes are strong candidates to be the Angelman gene, but neither can be eliminated as possibilities with the available data.