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Cloning of P2XM, a novel human P2X receptor gene regulated by p53
1Laboratory of Molecular Medicine, The Institute of Medical Science, The University of Tokyo, Minato-ku, Japan.
Abstract:
Through cloning of functional p53-binding sites (p53-tagged sites) from the human genome, we isolated a novel gene inducible by wild-type p53. Its cDNA sequence contained an open reading frame encoding a 431-amino acid peptide that showed a significant homology with members of the P2X family. This protein also revealed a similarity to RP-2, a gene activated in thymocytes undergoing programmed cell death. Northern blot analysis showed that it was expressed predominantly in skeletal muscle. Hence, we designated the gene P2XM (P2X specifically expressed in skeletal muscle). P2XM was localized to chromosomal band 22q11, where frequent loss of heterozygosity has been observed in rhabdoid tumors. Although we detected no genetic alteration in the coding sequences, one of four rhabdomyosarcoma cell lines examined had completely lost expression of this gene. Furthermore, a minor splice variant lacking a part of exon 1 that would encode residues corresponding to transmembrane domain M1 was relatively more abundant in two of seven sarcoma cell lines, one of which was derived from a rhabdomyosarcoma, and the other was derived from an osteosarcoma. The results suggest that P2XM may play a significant role in the proliferation and/or differentiation of skeletal muscle cells and that its altered expression may be involved in the development of some sarcomas.
Insights
Researchers identified a new gene, P2XM, in skeletal muscle that is activated by p53. Altered P2XM expression may contribute to sarcoma development.
Area of Science:
- Molecular Biology
- Genetics
- Oncology
Background:
- The p53 tumor suppressor protein plays a critical role in cellular responses to DNA damage.
- Identification of novel genes regulated by p53 is crucial for understanding cancer development.
Purpose of the Study:
- To identify and characterize novel genes induced by wild-type p53.
- To investigate the role of a newly identified gene, P2XM, in skeletal muscle and its potential involvement in sarcomas.
Main Methods:
- Cloning of p53-binding sites from the human genome.
- cDNA sequencing and homology analysis.
- Northern blot analysis for gene expression profiling.
- Chromosomal localization and analysis of gene alterations in cancer cell lines.
Main Results:
- A novel gene, P2XM, was isolated and found to be inducible by wild-type p53.
- P2XM encodes a 431-amino acid peptide homologous to the P2X family and RP-2.
- P2XM is predominantly expressed in skeletal muscle and localized to chromosome 22q11.
- Loss of P2XM expression was observed in a rhabdomyosarcoma cell line, and splice variants were found in sarcoma cell lines.
Conclusions:
- P2XM may be involved in skeletal muscle cell proliferation and differentiation.
- Altered P2XM expression is potentially linked to the pathogenesis of certain sarcomas.