SEARCH · PubMed Health

Results for “MutS Homolog 3 Protein”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1996

hMutSbeta, a heterodimer of hMSH2 and hMSH3, binds to insertion/deletion loops in DNA.

In human cells, mismatch recognition is mediated by a heterodimeric complex, hMutSalpha, comprised of two members of the MutS homolog (MSH) family of proteins, hMSH2 and GTBP [1,2]. Correspondingly, tumour-derived cell lines defective in hMSH2 and GTBP have a mutator phenotype [3,4], and extracts prepared from these cells lack mismatch-binding activity [1]. However, although hMSH2 mutant cell lines showed considerable microsatellite instability in tracts of mononucleotide and dinucleotide repeats [4,5], only mononucleotide repeats were somewhat unstable in GTBP mutants [4,6]. These findings, together with data showing that extracts of cells lacking GTBP are partially proficient in the repair of two-nucleotide loops [2], suggested that loop repair can be GTBP-independent. We show here that hMSH2 can also heterodimerize with a third human MSH family member, hMSH3, and that this complex, hMutSbeta, binds loops of one to four extrahelical bases. Our data further suggest that hMSH3 and GTBP are redundant in loop repair, and help explain why only mutations in hMSH2, and not in GTBP or hMSH3, segregate with hereditary non-polyposis colorectal cancer (HNPCC) [7].

Base Sequence↗

PubMed1997

Role of Saccharomyces cerevisiae Msh2 and Msh3 repair proteins in double-strand break-induced recombination.

When gene conversion is initiated by a double-strand break (DSB), any nonhomologous DNA that may be present at the ends must be removed before new DNA synthesis can be initiated. In Saccharomyces cerevisiae, removal of nonhomologous ends depends not only on the nucleotide excision repair endonuclease Rad1/Rad10 but also on Msh2 and Msh3, two proteins that are required to correct mismatched bp. These proteins have no effect when DSB ends are homologous to the donor, either in the kinetics of recombination or in the proportion of gene conversions associated with crossing-over. A second DSB repair pathway, single-strand annealing also requires Rad1/Rad10 and Msh2/Msh3, but reveals a difference in their roles. When the flanking homologous regions that anneal are 205 bp, the requirement for Msh2/Msh3 is as great as for Rad1/Rad10; but when the annealing partners are 1,170 bp, Msh2/Msh3 have little effect, while Rad1/Rad10 are still required. Mismatch repair proteins Msh6, Pms1, and Mlh1 are not required. We suggest Msh2 and Msh3 recognize not only heteroduplex loops and mismatched bp, but also branched DNA structures with a free 3' tail.

DNA Damage↗

PubMed1997

Two pathways for removal of nonhomologous DNA ends during double-strand break repair in Saccharomyces cerevisiae.

During repair of a double-strand break (DSB) by gene conversion, one or both 3' ends of the DSB invade a homologous donor sequence and initiate new DNA synthesis. The use of the invading DNA strand as a primer for new DNA synthesis requires that any nonhomologous bases at the 3' end be removed. We have previously shown that removal of a 3' nonhomologous tail in Saccharomyces cerevisiae depends on the nucleotide excision repair endonuclease Rad1/Rad10, and also on the mismatch repair proteins Msh2 and Msh3. We now report that these four proteins are needed only when the nonhomologous ends of recombining DNA are 30 nucleotides (nt) long or longer. An additional protein, the helicase Srs2, is required for the RAD1-dependent removal of long 3' tails. We suggest that Srs2 acts to extend and stabilize the initial nascent joint between the invading single strand and its homolog. 3' tails shorter than 30 nt are removed by another mechanism that depends at least in part on the 3'-to-5' proofreading activity of DNA polymerase delta.

DNA Damage↗

PubMed2001

Instabilotyping: comprehensive identification of frameshift mutations caused by coding region microsatellite instability.

Coding region frameshift mutation caused by microsatellite instability (MSI) is one mechanism contributing to tumorigenesis in cancers with MSI in high frequency. Mutation of TGFBR2 is one example of this process. To identify additional examples, a large-scale genomic screen of coding region microsatellites was conducted. 1115 coding homopolymeric loci with six or more nucleotides were identified in an online genetic database. Mutational screening was performed at 152 of these loci in 46 colorectal tumors with MSI in high frequency. Nine loci were mutated in > or =20% of tumors, 10 loci in 10-20%, 24 loci in 5-10%, 43 loci in <5%, and 66 loci were not mutated in any tumors. The most frequently mutated novel loci were the activin type II receptor gene (58.1%), SEC63 (48.8%), AIM 2 (47.6%), a gene encoding a subunit of the NADH-ubiquinone oxidoreductase complex (27.9%), a homologue of mouse cordon-bleu (23.8%), and EBP1/PA2G4 (20.9%). This genome-wide approach identifies coding region MSI in genes or pathways not implicated previously in colorectal tumorigenesis, which may merit functional study or other additional analysis.

3' Untranslated Regions↗

PubMed2001

Mismatch repair and microsatellite instability in esophageal cancer cells.

Using in vitro mismatch repair (MMR) assay, we have identified 3 of 22 esophageal cancer cell lines exhibiting reduced MMR activity. By means of gel-shift assay, decreased binding ability to GT mismatch and CA loop was observed in these 3 cell lines. However, we could not find any mutations in the hMSH2, hMSH3 and hMSH6 genes, the protein products of which exhibit mismatch binding activity in human cells. In addition, when using antibodies against 5 MMR-related proteins (hMSH2, hMSH3, hMSH6, hPMS2 and hMLH1), no aberrant expression was detected in any of them. When we examined 9 microsatellite loci in endogenous genomic DNA, these 3 esophageal cancer cell lines, deficient in MMR, did not exhibit microsatellite instability. However, when we examined the repetitious sequence on exogenous plasmid DNA which was introduced into these 3 esophageal cancer cells, the results suggested that MMR deficiency in esophageal cancer cells could result in moderate instability of the exogenous sequence.

Adaptor Proteins, Signal Transducing↗

PubMed1998

RER phenotype and its associated mutations in familial gastric cancer.

To clarify the genetic background of gastric cancer, we collected 28 familial gastric cancers (FGCs) with reference to the Amsterdam criteria in hereditary non-polyposis colorectal cancer (HNPCC) and investigated the frequency of replication error (RER) at six microsatellite loci and frameshift mutations in its related genes in these tumors. RER was detected in seven (25%) of the 28 gastric cancers. Five (18%) cases showed RER at more than two loci. The apparent increased incidence of RER in FGC was not detected compared with that reported in sporadic gastric cancers previously. Among four cases with RER at more than three loci, frameshift mutations in the (A)8 track of the hMSH3 gene were detected in all the four cases and mutations in the (A)10 track of the transforming growth factor-beta type II receptor (TGF-beta RII) gene were detected in the three of them. Histologically, three of the four cases were of the intestinal type, and the other one was the diffuse type. No mutation was detected in the (C)8 and (GT)3 tracks of the hMSH6 and TGF-beta RII genes respectively. These results indicate that the acquisition of the RER phenotype equally influences the gastric carcinogenesis of both sporadic and familial cases, and that the majority of FGC is pathogenetically distinct from HNPCC.

Adult↗

PubMed2001

Differentially expressed cDNAs in PLCbeta3-induced tumor suppression in a human endocrine pancreatic tumor cell line: activation of the human mismatch repair protein 3 gene.

Phospholipase Cbeta3 (PLCB3) is located to chromosome 11q13 in the vicinity of the multiple endocrine neoplasia type1 (MEN1) gene and shows loss of expression in some neuroendocrine tumors. Transfection of PLCB3 to neuroendocrine cell lines induces growth suppression and phenotypic alterations, but the mechanisms remain unclear. To investigate the underlying events behind this tumor suppression, we performed an RT-Differential cDNA Display of total RNA from BON-1 (human endocrine pancreatic tumor cell line) transfected with PLCB3 and compared to wild type and BON-1 transfected with vector without insert. PLCB3 transfection resulted in increased expression of 4 genes and decreased of 2. The two inhibited were homologous to S100A3 and Chromogranin A. One of the four activated cDNAs could be identified as human mismatch repair protein 3 mRNA (hMSH3), and another was homologous to TIS/MA-3 mRNA (mouse topoisomerase suppressor inhibited gene/mouse apoptosis gene-3). Differential expression of these genes may contribute to the PLCB3-induced tumor suppression of neuroendocrine tumor cell lines.

Animals↗

PubMed2001

ATP binding to the first nucleotide-binding domain of multidrug resistance protein MRP1 increases binding and hydrolysis of ATP and trapping of ADP at the second domain.

Multidrug resistance protein (MRP1) utilizes two non-equivalent nucleotide-binding domains (NBDs) to bind and hydrolyze ATP. ATP hydrolysis by either one or both NBDs is essential to drive transport of solute. Mutations of either NBD1 or NBD2 reduce solute transport, but do not abolish it completely. How events at these two domains are coordinated during the transport cycle have not been fully elucidated. Earlier reports (Gao, M., Cui, H. R., Loe, D. W., Grant, C. E., Almquist, K. C., Cole, S. P., and Deeley, R. G. (2000) J. Biol. Chem. 275, 13098-13108; Hou, Y., Cui, L., Riordan, J. R., and Chang, X. (2000) J. Biol. Chem. 275, 20280-20287) indicate that intact ATP is observed bound at NBD1, whereas trapping of the ATP hydrolysis product, ADP, occurs predominantly at NBD2 and that trapping of ADP at NBD2 enhances ATP binding at NBD1 severalfold. This suggested transmission of a positive allosteric interaction from NBD2 to NBD1. To assess whether ATP binding at NBD1 can enhance the trapping of ADP at NBD2, photoaffinity labeling experiments with [alpha-(32)P]8-N(3)ADP were performed and revealed that when presented with this compound labeling of MRP1 occurred at both NBDs. However, upon addition of ATP, this labeling was enhanced 4-fold mainly at NBD2. Furthermore, the nonhydrolyzable ATP analogue, 5'-adenylylimidodiphosphate (AMP-PNP), bound preferentially to NBD1, but upon addition of a low concentration of 8-N(3)ATP, the binding at NBD2 increased severalfold. This suggested that the positive allosteric stimulation from NBD1 actually involves an increase in ATP binding at NBD2 and hydrolysis there leading to the trapping of ADP. Mutations of Walker A or B motifs in either NBD greatly reduced their ability to be labeled by [alpha-(32)P]8-N(3)ADP as well as by either [alpha-(32)P]- or [gamma-(32)P]8-N(3)ATP (Hou et al. (2000), see above). These mutations also strongly diminished the enhancement by ATP of [alpha-(32)P]8-N(3)ADP labeling and the transport activity of the protein. Taken together, these results demonstrate directly that events at NBD1 positively influence those at NBD2. The interactions between the two asymmetric NBDs of MRP1 protein may enhance the catalytic efficiency of the MRP1 protein and hence of its ATP-dependent transport of conjugated anions out of cells.

Adenosine Diphosphate↗

PubMed2001

The interaction of DNA mismatch repair proteins with human exonuclease I.

Exonucleolytic degradation of DNA is an essential part of many DNA metabolic processes including DNA mismatch repair (MMR) and recombination. Human exonuclease I (hExoI) is a member of a family of conserved 5' --> 3' exonucleases, which are implicated in these processes by genetic studies. Here, we demonstrate that hExoI binds strongly to hMLH1, and we describe interaction regions between hExoI and the MMR proteins hMSH2, hMSH3, and hMLH1. In addition, hExoI forms an immunoprecipitable complex with hMLH1/hPMS2 in vivo. The study of interaction regions suggests a biochemical mechanism of the involvement of hExoI as a downstream effector in MMR and/or DNA recombination.

Adaptor Proteins, Signal Transducing↗

PubMed1997

Altered replication and inverted repeats induce mismatch repair-independent recombination between highly diverged DNAs in yeast.

Replication, DNA organization, and mismatch repair (MMR) can influence recombination. We examined the effects of altered replication due to a mutation in the polymerase delta gene, long inverted repeats (LIRs) in motifs similar to those in higher eukaryotes, and MMR on intrachromosomal recombination between highly diverged (28%) truncated genes in Saccharomyces cerevisiae. A combination of altered replication and an LIR increased recombination up to 700-fold, while each alone led to a 3- to 20-fold increase. Homeologous recombination was not altered by pms1, msh2, and msh3 mismatch repair mutations. Similar to our previous observations for replication slippage-mediated deletions, there were > or = 5-bp identical runs at the recombination breakpoints. We propose that the dramatic increase in recombination results from enhancement of the effects of altered replication by the LIR, leading to recombinationally active initiating structures. Such interactions predict replication-related, MMR-independent genome changes.

Base Sequence↗

PubMed2001

Microsatellite instability in double primary cancers of the colorectum and stomach.

Little is known about genetic alterations of patients who present multiple primary cancers. We hypothesized that microsatellite instability (MSI) is one of the underlying genetic factors in the development of double primary cancers in colorectal cancer patients. We examined for MSI in 41 colorectal cancer patients who presented with extra-colonic primary cancers consisted of 17 gastric and 24 non-gastric cancers. Coincident MSI+ in tumors of two organs were observed in 3 (17.7%) of 17 patients with colon and stomach cancers and 0 of 24 patients with colon and non-gastric cancers (P =.03). In 17 patients with colon and stomach cancers, 6 (31.6%) of 19 colon cancers and 3 (17.7%) of 17 gastric cancers exhibited MSI+. Among four patients with metachronous colon cancers who were identified within the 41 double primary cancer patients, two patients were associated with the MSI+ phenotype. In summary, the prevalent coincidence of MSI suggests that genetic defect of mismatch repair deficiency may be responsible for a small subset of double primary cancers of the colorectum and stomach.

Aged↗

PubMed2001

Induction of MRP5 and SMRP mRNA by adriamycin exposure and its overexpression in human lung cancer cells resistant to adriamycin.

Acquired anticancer drug resistance in cancer cells is often a result of an increase in levels of the ATP binding cassette (ABC) transporters that export anticancer drugs from cancer cells, suggesting that anticancer drugs may induce genes that mediate drug resistance in cancer cells. In this study, the induction of anticancer drug transporter gene expression by Adriamycin was examined in human lung cancer cell lines. Increased expression of MDR1, MRP5 and SMRP mRNA was observed 48 hr after the initiation of Adriamycin exposure in human lung cancer PC-14 cells and cisplatin-resistant PC-14/CDDP cells, in a dose-dependent manner as measured by TaqMan real-time RT-PCR. The levels of MRP-1, MRP2 and LRP mRNA were not altered by Adriamycin exposure. The biologic functions of the MRP5 and SMRP genes have not been fully clarified. To elucidate the relationship between Adriamycin resistance and MRP5 and SMRP, mRNA levels of MRP5 and SMRP in Adriamycin-resistant cell lines were compared with the parental cells. Increased expression of MRP5 and SMRP mRNA was observed in all 3 cell lines (SBC-3/ADM, AdR MCF7 and K562/ADM) by Northern blot analysis and RNase protection assay. These results suggest that subacute exposure of lung cancer cells to Adriamycin induced MRP5 and SMRP and that long-term exposure with Adriamycin selected the MRP5- and SMRP-overexpressing lung cancer cells. MRP5 and SMRP is a candidate molecule for acquired Adriamycin resistance in addition to MDR1.

Antineoplastic Agents↗

PubMed2003

Mutation analysis of K-ras and beta-catenin genes related to O6-methylguanin-DNA methyltransferase and mismatch repair protein status in human gallbladder carcinoma.

O6-methylguanin-DNA methyltransferase (MGMT) is a DNA repair enzyme that transfers methyl groups from O6-methylguanine to itself. Alkylation of DNA at the O6 position of guanine is the first step by alkylating agents in inducing DNA mutations in an organism. When MGMT and the mismatch repair (MMR) system are impaired, O6-methylguanine mispairs with thymine during DNA replication, resulting in a G:C right curved arrow A:T transitional mutation in DNA. We obtained cancer lesions by manual micro-dissection (MMD) from 26 paraffin-embedded formalin-fixed gallbladder carcinoma and Laser Capture Micro-dissection (LCM) method from 10 fresh frozen specimens. Mutation analysis was performed on the micro-dissected samples for K-ras and beta-catenin genes. At codon 12 of the K-ras gene, the MMD and LCM methods detected mutations in 3 (11.5%) and 1 (10%) case, respectively. In exon 3 of beta-catenin gene, only 1 (3.8%) case revealed a mutation in MMD cancer foci. Two cases without MGMT or MMR expression revealed a G right curved arrow A transition mutation in the K-ras gene. The findings suggested that negative MGMT and MMR status contributed to a G:C right curved arrow A:T transitional mutation in the K-ras gene. However, K-ras and beta-catenin mutations were actually rare in GB carcinoma. Other gene mutations frequently occurring in gallbladder carcinoma might be affected by this negative MGMT and MMR status.

Base Pair Mismatch↗

PubMedDate not supplied

P-glycoprotein and MRP1 expression in axillary lymph node metastases of breast cancer patients.

BACKGROUND: Only little information on the expression of P-glycoprotein (P-gp) and MRP1 in metastases of breast carcinomas is currently available. The aim of the present study was to investigate the expression of these two proteins in axillary lymph node metastases of breast cancer patients. MATERIALS AND METHODS: We determined the expression of P-gp and MRP1 in axillary lymph node metastases of 63 breast cancer patients and, in 32 patients, compared this expression to the expression of corresponding primary tumors. P-gp was detected by means of C219 and Ab-2 monoclonal antibodies, and MRP1 by means of the MRPr1 monoclonal antibody. RESULTS: In lymph node metastases, P-gp expression was positive, usually at low levels, in 28 (44%) specimens whilst MRP1 expression was positive in all specimens with low, intermediate and high levels in 3 (5%), 46 (73%) and 14 (22%) specimens, respectively. The percentage of P-gp expression was slightly lower in lymph nodes than in primary tumors while MRP1 expression showed a higher staining intensity in lymph nodes than in their corresponding primary tumors. CONCLUSION: These data indicate that both P-gp and MRP1 are frequently expressed in lymph node metastases of breast cancer patients and that MRP1 expression is more pronounced in lymph node metastases than in corresponding primary tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Somatic hypermutation in MutS homologue (MSH)3-, MSH6-, and MSH3/MSH6-deficient mice reveals a role for the MSH2-MSH6 heterodimer in modulating the base substitution pattern.

Although the primary function of the DNA mismatch repair (MMR) system is to identify and correct base mismatches that have been erroneously introduced during DNA replication, recent studies have further implicated several MMR components in somatic hypermutation of immunoglobulin (Ig) genes. We studied the immune response in mice deficient in MutS homologue (MSH)3 and MSH6, two mutually exclusive partners of MSH2 that have not been examined previously for their role in Ig hypermutation. In Msh6(-)/- and Msh3(-)/-/Msh6(-)/- mice, base substitutions are preferentially targeted to G and C nucleotides and to an RGYW hot spot, as has been shown previously in Msh2(-)/- mice. In contrast, Msh3(-)/- mice show no differences from their littermate controls. These findings indicate that the MSH2-MSH6 heterodimer, but not the MSH2-MSH3 complex, is responsible for modulating Ig hypermutation.

Adenosine Triphosphatases↗

PubMed2002

Implication of protein kinase C in the regulation of DNA mismatch repair protein expression and function.

The DNA mismatch repair (MMR) proteins are essential for the maintenance of genomic stability of human cells. Compared with hereditary or even sporadic carcinomas, MMR gene mutations are very uncommon in leukemia. However, genetic instability, attested by either loss of heterozygosity or microsatellite instability, has been extensively documented in chronic or acute malignant myeloid disorders. This observation suggests that in leukemia some internal or external signals may interfere with MMR protein expression and/or function. We investigated the effects of protein kinase C (PKC) stimulation by 12-O-tetradecanoylphorbol-13-acetate (TPA) on MMR protein expression and activity in human myeloid leukemia cell lines. First, we show here that unstimulated U937 cells displayed low level of PKC activity as well as MMR protein expression and activity compared with a panel of myeloid cell lines. Second, treatment of U937 cells with TPA significantly increased (3-5-fold) hMSH2 expression and, to a lesser extent, hMSH6 and hPMS2 expression, correlated to a restoration of MMR function. In addition, diacylglycerol, a physiological PKC agonist, induced a significant increase in hMSH2 expression, whereas chelerythrine or calphostin C, two PKC inhibitors, significantly decreased TPA-induced hMSH2 expression. Reciprocally, treatment of HEL and KG1a cells that exhibited a high level of PKC expression, with chelerythrine significantly decreased hMSH2 and hMSH6 expression. Moreover, the alteration of MMR protein expression paralleled the difference in microsatellite instability and cell sensitivity to 6-thioguanine. Our results suggest that PKC could play a role in regulating MMR protein expression and function in some myeloid leukemia cells.

Base Pair Mismatch↗

PubMed2001

Antisense hairpin loop oligonucleotides as inhibitors of expression of multidrug resistance-associated protein 1: their stability in fetal calf serum and human plasma.

Multidrug resistance-associated protein (MRP1) is a transmembrane pump protein responsible for the efflux of chemotherapeutic drugs, an important cause of anticancer treatment failure. Trying to circumvent MRP-mediated resistance we designed and synthesized hairpin loops forming antisense oligodeoxyribonucleotides (ODNs), both phosphodiesters (PO-ODNs) and their phosphorothioate analogues (PS-ODNs), to reduce the protein expression by targeting its mRNA in a sequence specific manner. Melting temperature measurements as well as polyacrylamide gel electrophoresis supported the preferential formation of a secondary structure, which was expected to protect ODNs against 3'-exonuclease degradation. ODNs and PS-ODNs designed in this work were successfully tested as antisense inhibitors of the expression of MRP1 in the leukaemia HL60/ADR cell line. Foreseeing the necessity to perform clinical studies with such ODNs we investigated their stability against the 3'-exonuclease activity of fetal calf serum and human plasma. Under the conditions, corresponding to physiological ones, we observed high stability of hairpin loop forming ODNs, especially those containing longer (e.g. 7 base pair) stems. Comparative studies on the stability of chemically unmodified hairpin loop forming ODNs and their PS-counterparts indicated that endonuclease activity did not play any important role in the process of their nucleolytic degradation. Our studies provide strong evidence for high stability of chemically unmodified hairpin loop ODNs, making them an attractive alternative to phosphorothioate analogues commonly used in antisense strategy.

Animals↗

PubMed1998

Mutations at coding mononucleotide repeats in gastric cancer with the microsatellite mutator phenotype.

We analysed 50 gastric carcinomas (GCs) to verify whether mutations at coding repeats were associated with microsatellite instability (MSI). The tumors included: ten cases with no MSI, 14 cases with MSI = 1 locus, 13 cases with MSI = two loci and 13 cases with MSI > or = 3 loci. We investigated coding repeats within the TGF-beta RII, IGFIIR, BAX, hMSH6, hMSH3 and BRCA2 genes. The TGF-beta RII, IGFIIR, BAX, hMSH6 and hMSH3 repeats were altered in 11 (22%), five (10%), four (8%), 16 (32%) and five (10%) cases respectively. Mutations occurred only in MSI-positive (MSI+) tumors and correlated with increasing MSI levels. No alterations of the BRCA2 repeat were found. Mutations in genes other than hMSH6 were strongly associated to hMSH6 mutations, suggesting a key role of this gene. The non-coding BAT-26 and E-Cadherin 3' UTR poly(A)8/(T)15 repeats were analysed in 44 of the 50 cases. Novel tumor-associated alleles were observed only in MSI-positive GCs and were in most cases associated with mutations at coding repeats. Further investigations with BAT-40 confirmed that four cases manifested mononucleotide repeat alterations restricted to hMSH6 and one case to TGF-beta RII. A subset of tumors with MSI at two or more dinucleotide loci resulted negative for mutations at coding and non-coding mononucleotide repeats.

Aged↗