Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving antigen-antibody binding – specific binding protein...
Reexamination Certificate
2001-11-21
2004-09-21
Ketter, James (Department: 1636)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving antigen-antibody binding, specific binding protein...
C435S004000, C435S006120
Reexamination Certificate
active
06794147
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to animals in which the MutS homolog 4 (MSH4) gene is misexpressed and methods of using such animals or cells derived therefrom, e.g., in methods of evaluating fertility treatments.
BACKGROUND OF THE INVENTION
The DNA mismatch repair system (MMR) in mammalian cells is responsible for the repair of DNA mismatches that can result from a number of different mechanisms including DNA replication, genetic recombination and chemical modification of DNA or nucleotide pools. Studies in yeast, and more recently in mice, have also revealed a role for M proteins in the control of meiotic recombination. The bacterial DNA mismatch repair system typified by the
E. coli
Mut HLS system is the simplest and best understood. This system is capable of repairing both single nucleotide mismatches as well as small insertion/deletion mismatches (Kolodner, R. (1996)
Genes Dev
10: 1433-1442, Modrich, P. et al. (1996)
Annu Rev Biochem
65: 101-133). In
E. coli
, the Mut S protein recognizes and binds to mismatched nucleotides. In a subsequent step a second protein, Mut L, interacts with Mut S and activates a third protein, Mut H, which is an endonuclease. Mut H nicks the unmethylated strand of hemimethylated DNA in the vicinity of a mismatch, thereby directing the repair of the newly synthesized strand.
While the essential components of this MMR system have been conserved in eukaryotes, the repair system is more complex than in
E. coli
and involves several Mut S and Mut L homologs. In yeast
Saccharomyces cerevisiae
there are six homologs of the DNA binding protein Mut S designated Mut S homolog (MSH) 1-6. There are also four known homologs of the Mut L gene in yeast, designated MLH1, MLH2, PMS1 and MLH3 (Kolodner, R. (1996)
Genes Dev
10: 1433-1442, Crouse, G. F. (1998)
InDNA Repair in Prokaryotes and Lower Eukaryotes
pp. 411-448). The mammalian genome has homologs for all of these genes except MSH1 which, if present, is yet to be discovered (Buermeyer, A. B., et al (1999)
Annu. Rev. Genet
. 33: 533-564, Kolodner, R. (1996)
Genes Dev
10: 1433-1442).
It is well established that in eularyotes the products of the MSH2, MSH3, MSH6, as well as MLH1, PMS1 and MLH3 genes are involved in DNA mismatch repair. In eukaryotes, MMR requires a complex of MSH2-MSH6 for the repair of single base mispairs and either a complex of MSH2-MSH6 or MSH2-MSH3 for the repair of insertion/deletion mispairs (Acharya, S. et al. (1996)
Proc Natl Acad Sci USA
93: 13629-13634, Marsischky, G. T. et al. (1996)
Genes Dev
10: 407-420, Genschel, J. et al. (1998)
J Biol Chem
273: 19895-19901, Guerrette, S., et al. (1998)
Mol Cell Biol
18: 6616-6623, Umar, A. et al. (1998)
Genetics
148: 1637-1646). The two MSH complexes interact with the complexes of MLH1-PMS1 (PMS2 in human) or MLH1-MLH3 for the repair of the different mismatches (Prolla, T. A. et al. (1998)
Nat Genet
18: 276-279, Li, G. M. et al. (1995)
Proc Natl Acad Sci USA
92: 1950-1954, Habraken, Y. et al. (1997)
Curr Biol
7: 790-793, Pang, Q. et al. (1997)
Mol Cell Biol
17: 4465-4473, Flores-Rozas, H. et al. (1998)
Proc Natl Acad Sci USA
95: 12404-12409, Wang, T. F. et al. (1999)
Proc Natl Acad Sci USA
96: 13914-13919).
Germ line mutations in some of the MMR genes in humans are associated with the cancer predisposition syndrome, hereditary non-polyposis colon cancer (HNPCC). This syndrome is inherited in an autosomal dominant fashion and is characterized by a predispostion to develop colonic and extracolonic tumors where the tumors have a characteristic replication error (RER
+
) phenotype (Kinzler, K. W. et al. (1996)
Cell
87: 159-170). Germ-line mutations in MSH2 and MLH1 account for a majority of HNPCC families (Peltomaki, P. et al. (1997)
Gastroenterology
113: 1146-1158). Recently it is was found that MSH6 germ-line mutations account for a small number of HNPCC families but appear to be also responsible for a larger number of late-onset familial colorectal cancer cases (Wu, Y. et al. (1999)
Am J Hum Genet
65: 1291-1298).
Studies in bacteria and yeast showed that the MMR system is also involved in the control of recombination. For example, genetic analysis in yeast showed that the complexes consisting of the MMR proteins MSH2-MSH6, MSH2-MSH3, and MLH1-PMS1 function in the prevention of recombination between divergent DNA sequences. This role in recombination is dependent on interactions with other proteins including RAD1-RAD10 and EXO1 (Nakagawa, T. et al. (1999)
Proc Natl Acad Sci USA
96: 14186-14188). Two other members of the yeast MSH family, MSH4 and MSH5, play a role specifically in meiotic recombination. Yeast strains carrying null mutations in either MSH4 or MSH5 show reduced rates of crossing over but not gene conversion, increased chromosomal nondisjunction and reduced spore viability (Ross-Macdonald, P. et al. (1994)
Cell
79: 1069-1080, Hollingsworth, N. M. et al. (1995)
Genes Dev
9: 1728-1739). The analysis of MSH4/MSH5 double mutant yeast strains indicates that MSH4 and MSH5 function in the same genetic pathway with MSH5 being epistatic to MSH4 (Hollingsworth, N. M. et al. (1995)
Genes Dev
9: 1728-1739). Yeast MSH4 and MSH5 are able to form heterodimeric complexes similar to the mitotic MSH proteins (Pochart, P., D. et al. (1997)
J Biol Chem
272: 30345-30349). In a manner analogous to mitotic MMR, the analysis of MSH4/MLH1 double mutant yeast strains indicated that the meiosis specific MutS homologs require the function of MLH1 for the promotion of meiotic crossing-over (Hunter, N. et al. (1997)
Genes Dev
11: 1573-1582).
To understand the role of the mammalian mismatch repair genes in DNA repair, cancer predisposition and meiosis, several mouse lines with targeted mutations in MMR genes have been generated. Mice that carry mutations in the mismatch repair genes Msh2 (de Wind et al. (1995)
Cell
82:321-330; Reitmair et al. (1995)
Nat Genet
11:64-70), Msh3 (de Wind et al. (1999)
Nat Genet
23:359-362; Edelmann et al. (2000)
Cancer Res
60:803-807), Msh6 (Edelmann et al. (1997)
Cell
91:467-477), Mlh1 (Baker et al. (1996)
Nat Genet
13:336-342; Edelmann et al. (1996)
Cell
85:1125-1134), Pms2 (Baker et al. (1995)
Cell
82:309-319) and
Pms
1 (Prolla et al. (1998)
Nat Genet
18:276-279) have been described. Msh2
−/−
, Mlh1
−/−
, Msh6
−/−
and Pms2
−/−
mice display a predisposition to tumors, although the degree of this predisposition and the latency for tumor development differ. Mice lacking Msh3 and Pms1 are reported to be normal.
Mice that are homozygous for mutations in the somatic members of the MSH gene family (Msh2, Msh3 and Msh6), are viable and fully fertile (de Wind et al. (1995)
Cell
82:321-330; Reitmair et al. (1995)
Nat Genet
11:64-70; Edelmann et al. (1997)
Cell
25 91:467-477); Edelmann et al. (2000)
Cancer Res
60:803-807). However, mice that are mutant for the mutL homologs Pms2 and Mlh1 also exhibit a meiotic defect in addition to their cancer predisposition phenotypes. Male mice bearing a homozygous mutation in Pms2 show abnormal chromosome pairing during meiosis and are sterile while the females are fertile (Baker et al. (1995)
Cell
82:309-319). Mice with mutations in the Mlh1 gene are viable but both sexes are sterile. In spermatocytes from Mlh1 mutant males normal chromosome pairing was observed in pachynema of prophase I, but most of the cells fail to progress beyond pachynema (Baker et al. (1996)
Nat Genet
13:336-342; Edelmann et al. (1996)
Cell
85: 1125-1134).
The observation that mutations in the mutL homologous genes result in a different meiotic phenotype compared to mutations in the mutS homologous genes with which they interact during mitotic DNA mismatch repair indicates that the MLH proteins employ different members of the MSH family as partners during meiosis. Recently the human homologs of the yeast MSH4 and MSH5 genes have been isolated and their expression in human germ cells (Paquis-Flucklinger et al. (1997)
Genomics
44:188-194; Her C. et al. (1998)
Genomics
52
Cohen Paula E.
Edelmann Winfried
Kneitz Burkhard
Kucherlapati Raju S.
Pollard Jeffrey W.
DiRocco Lisa M.
Ketter James
Lahive & Cockfield LLP
Lambertson David A.
Mandragouras Amy E.
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