SPO13 and SPO12

Meiosis: SPO13 and SPO12 ensure that cells undergo proper separation of homologs at MI. The regulation and function of these two genes, identified in our lab, has been a focus of much of our research over the past several years. SPO13 is induced 75-fold early in meiosis by the Ume6/Ime1 activator complex, while SPO12 (also transcribed in mitosis) is induced 5-fold in mid-meiosis. Loss of either gene has little or no effect on mitosis, but typically causes diploid cells to bypass MI and undergo a single MII-like division, resulting in dyads with two viable diploid spores. Mutations in SPO13 also allow haploid cells to undergo a successful meiosis, resulting in two viable haploid spore. Spo13 is thought to promote reductional chromosome segregation by participating in the establishment of sister centromere cohesion or by interfacing with the cell cycle machinery to delay the M/A transition until cohesion occurs or is stabilized.

Mitosis: When expressed in mitosis, SPO13 functions as a negative regulator of division resulting in a cell cycle arrest at the metaphase to anaphase transition. We have shown that this M-phase delaying activity requires regulatory machinery (CDC28) common to mitosis and meiosis, and have proposed that the delay is necessary for homologs to undergo the modifications necessary for sister centromere/chromatid cohesion and proper segregation of homologs. SPO12 has been shown to promote exit from M-phase when overexpressed in mitosis, and may perform a similar function in the first meiotic division.

Selected References Recombination can partially substitute for SPO13 in regulating meiosis I in budding yeast. Rutkowski LH, Esposito RE. Genetics. 2000 Aug;155(4):1607-21. [PubMed] UME6 is a central component of a developmental regulatory switch controlling meiosis-specific gene expression. Steber CM, Esposito RE. Proc Natl Acad Sci U S A. 1995 Dec 19;92(26):12490-4. [PubMed] SPO13 negatively regulates the progression of mitotic and meiotic nuclear division in Saccharomyces cerevisiae. McCarroll RM, Esposito RE. Genetics. 1994 Sep;138(1):47-60. [PubMed] Nucleotide sequence and promoter analysis of SPO13, a meiosis-specific gene of Saccharomyces cerevisiae. Buckingham LE, Wang HT, Elder RT, McCarroll RM, Slater MR, Esposito RE. Proc Natl Acad Sci U S A. 1990 Dec;87(23):9406-10. [ PubMed] Developmental regulation of SPO13, a gene required for separation of homologous chromosomes at meiosis I. Wang HT, Frackman S, Kowalisyn J, Esposito RE, Elder R. Mol Cell Biol. 1987 Apr;7(4):1425-35. [ PubMed] Meiosis in haploid yeast. Wagstaff JE, Klapholz S, Esposito RE. Proc Natl Acad Sci U S A. 1982 May;79(9):2986-90. [ PubMed] Recombination and chromosome segregation during the single division meiosis in SPO12-1 and SPO13-1 diploids. Klapholz S, Esposito RE. Genetics. 1980 Nov;96(3):589-611. [ PubMed] Isolation of SPO12-1 and SPO13-1 from a natural variant of yeast that undergoes a single meiotic division. Klapholz S, Esposito RE. Genetics. 1980 Nov;96(3):567-88. [ PubMed]