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Biomedical subjects

D Lazarevic

Publications and source records attributed to D Lazarevic.

7 recordsLinked to original sources
PubMed2000

Cloning, chromosome mapping and functional characterization of a human homologue of murine gtse-1 (B99) gene.

Murine Gtse-1 (G(2) and S phase expressed protein), previously named B99, is a wt-p53 inducible gene that encodes a microtubule-localized protein which is able to induce G(2)/M phase accumulation when ectopically expressed. Here we report the cloning and characterization of a new cDNA (GTSE-1) encoding a human homologue of the mouse Gtse-1 protein. Chromosome mapping of mouse and human genes assigned Gtse-1 to chromosome 15 and GTSE-1 to chromosome 22q13.2-q13.3 in a region with conserved synteny to that where Gtse-1 mapped. Analysis of the genomic structure revealed that GTSE-1 contains at least 11 exons and 10 introns, spanning approximately 33kb of genomic DNA. Similar to murine Gtse-1, the product of GTSE-1 localized to the microtubules, was able to delay G(2)/M progression when ectopically expressed and was cell cycle regulated. Taken together, these results indicate GTSE-1 as the human functional homologue of murine Gtse-1.

Amino Acid Sequence↗
PubMed1999

wt p53 dependent expression of a membrane-associated isoform of adenylate kinase.

Six novel p53-inducible transcripts were recently cloned from Val5, a murine cell line stably expressing a temperature-sensitive p53 allele. One of the isolated clones represented a novel isoform of cytosolic adenylate kinase (AK1), a highly conserved monomeric enzyme involved in cellular homeostasis of adenine nucleotides. The corresponding protein, which we named AK1beta, was specifically induced upon activation of wt p53 in Val5 cells. The AK1beta protein differs from cytoplasmic AK1 by having 18 extra amino acids at the N-terminus. The extra residues in AK1beta provide a consensus signal for N-terminal myristoylation; as expected, AK1beta was shown to localize to the plasma membrane. The human AK1 gene contains several consensus p53 binding sites and we report that p53-dependent induction of the alternative AK1beta transcript also occurs in human cells. By using antisense ablation experiments in Val5 fibroblasts we show that AK1beta plays a relevant role in the establishment of reversible cell-cycle arrest as induced by p53 in these cells. These findings suggest that within a p53-dependent genetic program, a specific isoform of adenylate kinase has a previously undescribed growth-regulatory function, which might not necessarily require its best characterized biochemical activity.

3' Untranslated Regions↗
PubMed1997

Dismantling cell-cell contacts during apoptosis is coupled to a caspase-dependent proteolytic cleavage of beta-catenin.

Cell death by apoptosis is a tightly regulated process that requires coordinated modification in cellular architecture. The caspase protease family has been shown to play a key role in apoptosis. Here we report that specific and ordered changes in the actin cytoskeleton take place during apoptosis. In this context, we have dissected one of the first hallmarks in cell death, represented by the severing of contacts among neighboring cells. More specifically, we provide demonstration for the mechanism that could contribute to the disassembly of cytoskeletal organization at cell-cell adhesion. In fact, beta-catenin, a known regulator of cell-cell adhesion, is proteolytically processed in different cell types after induction of apoptosis. Caspase-3 (cpp32/apopain/yama) cleaves in vitro translated beta-catenin into a form which is similar in size to that observed in cells undergoing apoptosis. beta-Catenin cleavage, during apoptosis in vivo and after caspase-3 treatment in vitro, removes the amino- and carboxy-terminal regions of the protein. The resulting beta-catenin product is unable to bind alpha-catenin that is responsible for actin filament binding and organization. This evidence indicates that connection with actin filaments organized at cell-cell contacts could be dismantled during apoptosis. Our observations suggest that caspases orchestrate the specific and sequential changes in the actin cytoskeleton occurring during cell death via cleavage of different regulators of the microfilament system.

3T3 Cells↗
PubMed1996

Cyclin D1 and p21/waf1 are both involved in p53 growth suppression.

Overexpression of the wild type p53 gene in normal and transformed cells induces G1 arrest of cellular proliferation. In cell lines carrying the valine 135 temperature-sensitive p53 mutant gene, restoration of wild type p53 protein conformation at the permissive temperature causes an increase in the levels of cyclin D1, as well as the cyclin/cdk inhibitor p21/waf1. Accumulation of cyclin D1 is the result both of (post)transcriptional and post-translational regulatory mechanisms. Ablation of cyclin D1 induction by antisense cDNA microinjection significantly delays the onset of growth arrest, indicating that increased cyclin D1 levels likely contribute to wild type p53 G1 arrest. Whereas antisense ablation of either cyclin D1 or p21/waf1 can delay the onset of p53-induced growth arrest, ablation of neither is able to overcome a pre-existing p53-induced G1 block. In summary, the accumulated evidence indicate that induction of both cyclin D1 and p21/waf1 are involved in establishing the p53-mediated growth arrest in murine cell lines expressing temperature sensitive p53 protein.

Amino Acid Sequence↗