Biomedical subjects

M Zeremski

Publications and source records attributed to M Zeremski.

8 recordsLinked to original sources

PubMed2000

Differential association of products of alternative transcripts of the candidate tumor suppressor ING1 with the mSin3/HDAC1 transcriptional corepressor complex.

The candidate tumor suppressor ING1 was identified in a genetic screen aimed at isolation of human genes whose expression is suppressed in cancer cells. It may function as a negative growth regulator in the p53 signal transduction pathway. However, its molecular mechanism is not clear. The ING1 locus encodes alternative transcripts of p47(ING1a), p33(ING1b), and p24(ING1c). Here we report differential association of protein products of ING1 with the mSin3 transcriptional corepressor complex. p33(ING1b) associates with Sin3, SAP30, HDAC1, RbAp48, and other proteins, to form large protein complexes, whereas p24(ING1c) does not. The ING1 immune complexes are active in deacetylating core histones in vitro, and p33(ING1b) is functionally associated with HDAC1-mediated transcriptional repression in transfected cells. Our data provide basis for a p33(ING1b)-specific molecular mechanism for the function of the ING1 locus.

3T3 Cells↗

PubMed1999

Structure and regulation of the mouse ing1 gene. Three alternative transcripts encode two phd finger proteins that have opposite effects on p53 function.

The human ING1 gene encodes nuclear protein p33(ING1), previously shown to cooperate with p53 in cell growth control (Garkavtsev, I., Grigorian, I. A., Ossovskaya, V. S., Chernov, M. V., Chumakov, P. M., and Gudkov, A. V. (1998) Nature 391, 295-298). p33(ING1) belongs to a small family of proteins from human, mouse, and yeast of approximately the same size that show significant similarity to one another within the C-terminal PHD finger domain and also contain an additional N-terminal region with subtle but reliably detectable sequence conservation. Mouse ing1 is transcribed from three differently regulated promoters localized within a 4-kilobase pair region of genomic DNA. The resulting transcripts share a long common region encoded by a common exon and differ in their 5'-exon sequences. Two transcripts are translated into the same protein of 185 amino acids, the mouse equivalent of the human p33(ING1), while the third transcript encodes a longer protein that has 94 additional N-terminal amino acids. Overexpression of the longer protein interferes with the accumulation of p53 protein and activation of p53-responsive promoters after DNA damage. Between the two products of ing1, only the longer one forms a complex with p53 detectable by immunoprecipitation. These results indicate that a single gene, ing1, encodes both p53-suppressing and p53-activating proteins that are regulated by alternative promoters.

3T3 Cells↗

PubMed1997

Intracellular localization of p53 tumor suppressor protein in gamma-irradiated cells is cell cycle regulated and determined by the nucleus.

DNA damage leads to the stabilization of p53 protein and its translocation to the nucleus, resulting in activation or suppression of p53-responsive genes. However, a significant proportion of cell nuclei remain negative for p53 and p53-inducible cyclin-dependent kinase inhibitor p21waf1 after a single dose of gamma-irradiation. Quantitation of DNA content in p53-positive and -negative nuclei 4-6 h after 10 Gy of gamma-irradiation of human breast carcinoma MCF7 cells, fibrosarcoma HT1080 cells, and diploid skin fibroblasts showed that p53 and p21waf1 nuclear accumulation occurs predominantly in the G1 phase and at the beginning of the S phase of the cell cycle. The majority of the nuclei in late S phase and in G2-M phase remained p53- and p21waf1-negative. This suggests that there is a cell cycle window during which p53 can accumulate in the nucleus and activate expression of p21waf1. To determine whether cell cycle-dependent distribution of p53 is caused by cytoplasmic modifications of p53 protein or by properties of the nucleus, p53 localization was analyzed in multinucleated cells obtained by polyethylene glycol-mediated cell fusion. Dramatic differences in p53 accumulation were found among the nuclei in individual multinucleated cells. Distribution of p53-positive and -negative nuclei among the phases of the cell cycle was similar to that observed in a regular cell population. These results suggest that the observed differences in p53 accumulation in the nuclei of irradiated cells are determined by cell cycle-dependent nuclear functions. In contrast to p53, p21waf1 was equally distributed among the nuclei of multinucleated cells regardless of the stage of the cell cycle, indicating that the observed phenomenon is specific for p53.

Breast Neoplasms↗

PubMed1997

Localization of the candidate tumor suppressor gene ING1 to human chromosome 13q34.

A novel gene ING1 was recently cloned and defined as a candidate tumor suppressor gene. Reduced expression and rearrangements of ING1 are found in several tumor cell lines, ING1 overexpression is associated with cell growth arrest and ING1 suppression promotes neoplastic transformation (1). Using radiation hybrid mapping technique ING1 was assigned to subtelomeric region of the long arm of human chromosome 13 (13q34) which is known to be frequently rearranged in squamous carcinomas of head and neck.

Animals↗

PubMed1996

Elk-1 can recruit SRF to form a ternary complex upon the serum response element.

The initial genomic response to serum growth factors is the transcriptional activation of a set of immediate-early genes. Serum-induced transcriptional activation of several of these genes involves the formation of a ternary complex that includes the serum response factor (SRF), a 62 kDa ternary complex factor (TCF) and a serum response element (SRE). TCF alone does not bind the SRE of the protooncogene c-fos, but requires the prior assembly of the SRF-SRE binary complex for it to be recruited into a ternary complex. Here we show that this SRF-SRE binary complex is not an obligatory prerequisite for the formation of a serum responsive ternary complex. We demonstrate that Elk-1, which has properties of TCF can recruit SRF into a ternary complex on elements that do not support formation of the SRF-DNA binary complex. We also show that for two immediate-early genes, pip92 and nur77, formation of the ternary complex may occur without the prior assembly of SRF-DNA binary complex. Finally, we show that the ability of different sequences to support formation of Elk-l-SRF-DNA ternary complex in vitro correlates with their ability to respond to serum growth factors in vivo. Our results suggest that a much broader range of DNA sequences than the consensus SRF and TCF binding sites can support ternary complex formation, and by inference, serum induction. Possible implications of these results are discussed.

3T3 Cells↗

PubMed1996

Discovering distinct genes represented in 29,570 clones from infant brain cDNA libraries by applying sequencing by hybridization methodology.

To discover all distinct human genes and to determine their patterns of expression across different cell types, developmental stages, and physiological conditions, a procedure is needed for fast, mutual comparison of hundreds of thousands (and perhaps millions) of clones from cDNA libraries, as well as their comparison against data bases of sequenced DNA. In a pilot study, 29,570 clones in duplicate from both original and normalized, directional, infant brain cDNA libraries were hybridized with 107-215 heptamer oligonucleotide probes to obtain oligonucleotide sequence signatures (OSSs). The OSSs were compared and clustered based on mutual similarity into 16,741 clusters, each corresponding to a distinct cDNA. A number of distinct cDNAs were successfully recognized by matching their 107-probe OSSs against GenBank entries, indicating the possibility of sequence recognition with only a few hundred randomly chosen oligomers.

Animals↗

PubMed1995

Clone clustering by hybridization.

DNA sequencing by hybridization (SBH) Format 1 technique is based on experiments in which thousands of short oligomers are consecutively hybridized with dense arrays of clones. In this paper we present the description of a method for obtaining hybridization signatures for individual clones that guarantees reproducibility despite a wide range of variations in experimental circumstances, a sensitive method for signature comparison at prespecified significance levels, and a clustering algorithm that correctly identifies clusters of significantly similar signatures. The methods and the algorithm have been verified experimentally on a control set of 422 signatures that originate from 9 distinct clones of known sequence. Experiments indicate that only 30 to 50 oligomer probes suffice for correct clustering. This information about the identity of clones can be used to guide both genomic and cDNA sequencing by SBH or by standard gel-based methods.

Algorithms↗

PubMed1993

DNA sequence determination by hybridization: a strategy for efficient large-scale sequencing.

The concept of sequencing by hybridization (SBH) makes use of an array of all possible n-nucleotide oligomers (n-mers) to identify n-mers present in an unknown DNA sequence. Computational approaches can then be used to assemble the complete sequence. As a validation of this concept, the sequences of three DNA fragments, 343 base pairs in length, were determined with octamer oligonucleotides. Possible applications of SBH include physical mapping (ordering) of overlapping DNA clones, sequence checking, DNA fingerprinting comparisons of normal and disease-causing genes, and the identification of DNA fragments with particular sequence motifs in complementary DNA and genomic libraries. The SBH techniques may accelerate the mapping and sequencing phases of the human genome project.

Animals↗