Abstract for presentation at 11th International Congress of Human Genetics

Why do de novo t(11;22)s arise only in sperm?: Analysis using a yeast model system

  • Dr Tamae Ohye, Div Molecular Genetics, Inst Compre Med Sci, Fujita Health Univ, Japan
  • Dr Hidehito Inagaki, Div Molecular Genetics, Inst Compre Med Sci, Fujita Health Univ, Japan
  • Dr Hiroshi Kogo, Div Molecular Genetics, Inst Compre Med Sci, Fujita Health Univ, Japan
  • Prof Beverly Emanuel, Div Human Genetics, Children's Hosp Philadelphia, United States
  • Prof Hiroki Kurahashi, Div Molecular Genetics, Inst Compre Med Sci, Fujita Health Univ, Japan

    • The constitutional t(11;22)(q23;q11) is the most frequently occurring non-Robertsonian translocation in humans. The breakpoints of the t(11;22) were identified within palindromic AT-rich repeats on chromosomes 11 (PATRR11) and 22 (PATRR22), suggesting that cruciform structures mediate double-strand-breaks (DSBs) leading to this recurrent translocation. De novo t(11;22)s are detected in sperm from healthy men at a frequency of 1/104-105, but never in lymphocytes or fibroblasts. To investigate the mechanism of sperm-specific generation of the t(11;22), we utilized a yeast model system for the t(11;22).
    We created a diploid yeast harboring the 445bp PATRR11 at the TRP1 locus on chromosome IV and the 595bp PATRR22 at the LEU2 locus on chromosome III. We isolated genomic DNA and performed translocation-specific PCR using primer pairs flanking the PATRR both on chromosomes IV and III. As a result, we successfully detected de novo translocation-specific PCR products. Based on our previous observation that the PATRRs prefer to adopt a cruciform conformation in a temperature-dependent manner, and the fact that the temperature of the testis is lower than that of other tissues, we examined the translocation frequency at various temperatures for yeast cultures. As a result of this analysis we determined that the translocation frequency was significantly higher at 25 degree than at 34 degree. Next, we determined the translocation frequency either in vegetative or meiotic yeast, finding a higher translocation frequency during meiosis.
    Our results suggest that complex factors such as temperature-dependent DNA conformation and meiosis-specific recombination machinery during spermatogenesis are likely to be involved in sperm-specific generation of the t(11;22) rearrangement.

    Conference Organiser - ICMS Pty Ltd