Neuroblastoma-associated regulator gene

Chemistry: molecular biology and microbiology – Animal cell – per se ; composition thereof; process of... – Primate cell – per se

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536 235, 536 2431, 4353201, 4352523, 530350, 530828, C07H 2104, C07K 1447

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056541880

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a gene which is affected significantly by tumour-specific deletions in human neuroblastomas and is involved in tumour genesis.
2. Description of Related Art
A group of proteins which have been shown to act predominantly as activators of transcription share common motifs for dimerisation and DNA binding (Jones, 1990). The dimerisation domain is an amphipathic Helix-Loop-Helix (HLH)-region, and the DNA-binding is made easier by a section of basic amino acids which precede the HLH domain (Murre et al., 1989a,b). Proteins which contain this basic Helix-bop-Helix pattern (bHLH) may form homo- and heterodimers. The modulation of the transcriptional activation by bHLH factors is brought about by another group of dimerising proteins. This was established in the course of identifying the Id protein, a protein which also contains a Helix-Loop-Helix pattern but which lacks the basic region (HLH proteins) (Benezra et a., 1990). Id forms heterodimers with some members of the family of the bHLH transcription factors. Since it lacks the basic region which is responsible for DNA binding, heterodimers which contain Id cannot bind DNA. Therefore, bHLH proteins are most probably regulated negatively by HLH proteins such as Id. Other examples of regulatory bHLH and HLH protein interactions are the genes of the Drosophila achaete-scute-complex and the extramacrochaetae (emc) gene (Ellis et al., 1990; Garell and Modolell, 1990). These genes have a function in developing the sense organs of the peripheral nervous system (Ghysen and Dambly-Chaudiere, 1989). In general, genes which code for Helix-Loop-Helix proteins are presumed to be involved in controlling cell differentiation.
Cell differentiation is one of the processes which is affected by neoplastic transformation. Therefore, the function of genes involved in the these processes must be disrupted in tumour cells. The appearance of both dominant and recessive mutations in tumours must reflect the normal function of the affected genes as either positive or negative regulators. Up till now, Helix-Loop-Helix proteins have only been found to have effects based on dominant mutations, eg. the oncogenic activation of myc genes (Luscher and Eisenmann, 1990; Zimmerman and Alt, 1990). However, in view of the different functions of the genes coding for HLH proteins it could also be borne in mind that genes of this type are affected by recessive mutations and therefore have properties which correspond to the tumour suppressor genes.
Allelic deletions in specific regions of the genome, which occur significantly frequently in tumour genomes, are used as marking points for the position of tumour suppressor genes (Weinberg, 1991). In investigations of human neuroblastomas a consensus deletion was defined in chromosome lp36.2-p36.1 (Weith et al., 1989). The allelic loss of this section in about 80-90% of the tumours investigated led to the supposition that a gene which prevents tumours is located in this region.


DESCRIPTION OF THE PREFERRED EMBODIMENTS

The aim of the present invention was to isolate such a gene.
The following procedure was used to solve the problem: In order to identify genes in the human chromosome lp36 region, a panel of lp36-specific microcloned DNA probes (Martinsson et al., 1989) was used to identify CpG Islands. CpG Islands represent DNA sections which are rich in CpG and 0.5-1 kbp long, which are associated with the 5' ends of numerous genes (Bird, 1986). The cytosine groups in the Islands are not methylated and therefore corresponding sequences of methylation-sensitive, rarely cutting restriction enzymes are recognised. Consequently, individual probes were hybridised with pulse field electrophoresis blots of genomic DNA which had been subjected to either single or double digestion with rarely cutting restriction enzymes. Those DNA probes which were located between two CpG Islands were expected to hybridise with fragments of the same size in different single and double digestion. The pro

REFERENCES:
Bader et al., "Dissociation of Suppression of Tumorigenicity and Differentiation in Vitro Effected by Transfer of Single Human Chromosomes into Human Neuroblastoma Cells," Cell Growth & Differ. 2:245-255 (May 1991).
Benezra et al., "The Protein Id: A Negative Regulator of Helix-Loop-Helix DNA Binding Proteins," Cell 61:49-59 (Apr. 6, 1990).
Bernard et al., "Sequence of the murine and human cellular myc oncogenes and two modes of myc transcription resulting from chromosome translocation in B lymphoid tumours," EMBO J. 2:2375-2383 (1983).
Bird, A., "CpG-rich islands and the function of DNA methylation," Nature 321:209-213 (May 15, 1986).
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Christy et al., "An Id-related helix-loop-helix protein encoded by a growth factor-inducible gene," Proc. Natl. Acad. Sci. USA 88:1815-1819 (Mar. 1991).
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Ellis et al., "extramacrochaetae, a Negative Regulator of Sensory Organ Development in Drosophilia, Defines a New Class of Helix-Loop-Helix Proteins," Cell 61:27-38 (Apr. 6, 1990).
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Garrell & Modolell, "The Drosophila extramacrocheatae Locus, an Antagonist of Proneural Genes That, Like These Genes, Encodes a Helix-Loop-Helix Protein," Cell 61:39-48 (Apr. 6, 1990).
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Schwab et al., "Amplified DNA with limited homology to myc cellular oncogene is shared by human neuroblastoma cell lines and a neuroblastoma tumour," Nature 305:245-248 (Sep. 15, 1983).
Versteeg et al., "N-myc Expression Switched Off and Class I Human Leukocyte Antigen Expression Switched On after Somatic Cell Fusion of Neuroblastoma Cells," Mol. & Cell. Biol. 10:5416-5423 (Oct. 1990).
Weinberg, R.A., "Tumor Suppressor Genes," Science 254:1138-1146 (Nov. 22, 1991).
Weith et al., "Neuroblastoma Consensus Deletion Maps to 1p36.1-2," Genes, Chrom. & Cancer 1:159-166 (1989).
Zimmerman et al., "Differential expression of myc family genes during murine development," Nature 319:780-783 (Feb. 27, 1986).
Zimmerman & Alt, "Expression and Function of Myc Family Genes," Critical Rev. Oncogen. 2:75-95 (1990).

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