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PBX2 and PBX3, new homeobox genes with extensive homology to the human proto-oncogene PBX1.

ABSTRACT: Two new homeobox genes, PBX2 and PBX3, were isolated on the basis of their extensive homology to PBX1, a novel human homeobox gene involved in t(1;19) translocation in acute pre-B-cell leukemias. The predicted Pbx2 and Pbx3 proteins are 92 and 94% identical to Pbx1 over a large region of 266 amino acids within and flanking their homeodomains, but all three proteins diverge significantly near their amino and carboxy termini. Chromosome in situ hybridizations demonstrated that the PBX genes are not clustered but map to separate chromosomal loci: PBX1, 1q23; PBX2, 3q22-23; PBX3, 9q33-34. Expression of PBX2 or PBX3 was not restricted to particular states of differentiation or development, as mRNA transcripts of these genes were detected in most fetal and adult tissues and all cell lines, unlike PBX1, which is not expressed in lymphoid cell lines. Similar to PBX1 RNA, PBX3 RNA is alternatively spliced to yield two translation products with different carboxy termini, a feature not observed for PBX2. Their extensive sequence similarity and widespread expression suggest a generalized, overlapping role for Pbx proteins in most cell types. Differences in their amino and carboxy termini may modulate their activities, mediated in part by differential splicing and, for PBX1, protein fusion following t(1;19) chromosomal translocation.

SUBMITTER: Monica K

PROVIDER: S-EPMC361792 | biostudies-other | 1991 Dec

REPOSITORIES: biostudies-other

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PBX2 and PBX3, new homeobox genes with extensive homology to the human proto-oncogene PBX1.

Monica K K Galili N N Nourse J J Saltman D D Cleary M L ML

Molecular and cellular biology 19911201 12

Two new homeobox genes, PBX2 and PBX3, were isolated on the basis of their extensive homology to PBX1, a novel human homeobox gene involved in t(1;19) translocation in acute pre-B-cell leukemias. The predicted Pbx2 and Pbx3 proteins are 92 and 94% identical to Pbx1 over a large region of 266 amino acids within and flanking their homeodomains, but all three proteins diverge significantly near their amino and carboxy termini. Chromosome in situ hybridizations demonstrated that the PBX genes are no ...[more]

PMID: 1682799

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Project description:BackgroundKIT is a proto-oncogene involved in diverse neoplastic processes. Aberrant kinase activity of the KIT receptor has been targeted by tyrosine kinase inhibitor (TKI) therapy in different neoplasias. In all the earlier studies, KIT expression was reported to be absent in meningiomas. However, we observed KIT mRNA expression in some meningioma cases. This prompted us to undertake its detailed analyses in meningioma tissues resected during 2008-2009.MethodsTumor tissues and matched peripheral blood samples collected from meningioma patients were used for detailed molecular analyses. KIT expression was ascertained immunohistochemically and validated by immunoblotting. KIT and KITLG transcript levels were discerned by reverse transcription quantitative real-time PCR (RT-qPCR). Similarly, KIT amplification and allele loss were assessed by quantitative real-time (qPCR) and validated by fluorescence in situ hybridization (FISH) on the neoplastic tissues. Possible alterations of the gene at the nucleotide level were analyzed by sequencing.ResultsContrary to earlier reports, KIT expression, was detected immunohistochemically in 20.6% meningioma cases (n = 34). Receptor (KIT) and ligand (KITLG) transcripts monitored by RT-qPCR were found to co-express (p = 0.048) in most of the KIT immunopositive tumors. 1/7 KIT positive meningiomas showed allele loss corroborated by reduced FISH signal in the corresponding neoplastic tissue. Sequence analysis of KIT showed M541L substitution in exon 10, in one of the immunopositive cases. However, its biological consequence remains to be uncovered.ConclusionsThis study clearly demonstrates KIT over-expression in the human meningiomas. The data suggest that up-regulated KIT transcription (p < 0.001), instead of gene amplification (p > 0.05), is a likely mechanism responsible for altered KIT expression. Thus, KIT is a potential candidate for detailed investigation in the context of meningioma pathogenesis.

Dataset Information

PBX2 and PBX3, new homeobox genes with extensive homology to the human proto-oncogene PBX1.

Publications

PBX2 and PBX3, new homeobox genes with extensive homology to the human proto-oncogene PBX1.

Similar Datasets

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