Molecular characterization of human TRPM‐2/clusterin, a gene associated with sperm maturation, apoptosis and neurodegeneration

Abstract

The TRPM‐2/clusterin gene and its cognate protein has been characterized in a number of species. Although the functional role, or roles, of the TRPM‐2/clusterin protein remains to be firmly established, the gene has been implicated in a variety of physiological processes, including sperm maturation, lipid transport, membrane remodelling and inhibition of the complement cascade. TRPM‐2/clusterin is induced de novo during the regression of the prostate and other hormone‐dependent tissues after hormone ablation, and is over‐expressed in several human neurodegenerative diseases including Alzheimer's disease, epilepsy and retinitis pigmentosa. We describe the genomic structure of the human TRPM‐2/clusterin gene which is organized into nine exons, ranging in size from 47 bp (exon I) to 412 bp (exon V), spanning a region of 16580 bp. Comparison with sequences registered in the databases shows that it has extensive similarity to the human protein designated as SP‐40,40 or complement‐lysis inhibitor (CLI), a protein that appears to block the membrane‐attack complex of complement. However, the cDNA sequences reported for SP‐40,40 and CLI diverge significantly in the 5′ untranslated region of the mRNA (coded for by exon I), raising the possibility that the TRPM‐2/clusterin gene is present in the human genome as a small multi‐gene family or that there are several alternate exon I sequences in the TRPM‐2 gene. Southern analysis and fluorescent in situ hybridization suggest that the clusterin gene is a single‐copy gene, and that, if alternative exon I sequences are present in the genome, they lie outside of the λ clones that have been characterized. Analysis of the promoter region of the human TRPM‐2/clusterin gene shows many similarities to the rat TRPM‐2/clusterin promoter including a putative control region containing several potential regulatory elements that may regulate the complex tissue‐specific control of the gene which must be constitutively expressed in some tissues but is inducible in others.

Overexpression of Bcl-2 inhibits alveolar cell apoptosis during involution and accelerates c-myc-induced tumorigenesis of the mammary gland in transgenic mice

“…SGP-2, for example, is not only induced during mammary gland involution but also during regression of the prostate upon androgenablation and in di erent tumor cell lines induced to undergo apoptosis (Wong et al, 1993(Wong et al, , 1994. Overexpression of TGF-b1 and p53, which are both induced during involution, led to apoptosis of mammary alveolar cells in transgenic mice (Kordon et al, 1995;Li et al, 1996a), pointing towards a functional role of these molecules in involution-associated apoptosis as well.…”

Identification and characterization of glycosylation sites in human serum clusterin

“…Previous studies of human serum clusterin have defined the protein and gene sequences and revealed several posttranslational processing events (Jenne & Tschopp, 1989;Kirszbaum et al, 1989Kirszbaum et al, , 1992de Silva et al, 1990ade Silva et al, , 1990bChoi-Miura et al, 1992;Wong et al, 1994). Species homologues display remarkable conservation of amino acid sequence and genomic organization, however, no significant homology has yet been detected with other known structures (Wong et al, 1993).…”

Studies of specific gene induction during apoptosis of cell lines conditionally immortalized by SV40

“…This hypothesis cannot be ruled out but seems unlikely according to the high constitutive level observed in temperature-insensitive cells in which p53 is inactivated by large T antigen ( [5] and data not shown). Furthermore, the conserved putative cis-element which appears to be the target for specific DNA-binding factors in the clusterin gene [26] does not look like a p53-binding site and a computer search in the clusterin gene sequence [27] does not reveal any p53-binding site in other parts of the gene (data not shown).…”