FUNCTIONAL ANALYSIS OF MAMMALIAN GAMETOGENESIS

SEXUAL REPRODUCTION DEPENDS ON THE CORRECT FORMATION OF HAPLOID GAMETES, ACHIEVED BY GERM CELLS (2N) GOING THROUGH MEIOSIS, WHERE ONE ROUND OF GENOME REPLICATION IS FOLLOWED BY TWO ROUNDS OF CHROMOSOME SEGREGATION. CONCOMITANTLY, GERM CELLS DIFFERENTIATE INTO HIGHLY SPECIALIZED CELLS, SPERMATOZOA, AND EGGS (1N). MAMMALIAN GAMETOGENESIS PRESENTS EXTREME SEXUAL DIMORPHISM. WHILE SPERMATOGENESIS IS A CONTINUOUS PROCESS THAT OCCURS DURING MOST ADULTHOOD, OOGENESIS STARTS DURING FETAL DEVELOPMENT AND SETS THE SIZE OF THE POOL OF GAMETES, THE OVARIAN RESERVE. AFTER PUBERTY, GERM CELLS ARE USED UNTIL THE RESERVE IS FINISHED. THEN, OVARIAN FUNCTION ENDS, RESULTING IN A GENERAL HORMONAL IMBALANCE, MENOPAUSE. IN HUMANS, ASSOCIATED WITH THIS THERE IS A RISE IN THE PREDISPOSITION TO SUFFERING DISEASES, SUCH AS OSTEOPOROSIS, TYPE 2 DIABETES, OR CARDIOVASCULAR DISEASES. FURTHERMORE, ERRORS DURING GAMETOGENESIS CAN CAUSE OTHER CRITICAL SOCIAL ISSUES LIKE ANEUPLOIDY OR INFERTILITY. THE MAIN OBJECTIVE OF OUR RESEARCH TEAM IS TO REVEAL THE MECHANISMS THAT PROMOTE PROPER RECOMBINATION, SYNAPSIS, AND MEIOTIC PROGRESSION CONTROL TO UNDERSTAND THEIR IMPACT ON HUMAN FERTILITY. WE ARE CONFIDENT THAT BY BETTER UNDERSTANDING THESE PROCESSES, WE WILL BE ABLE TO IDENTIFY THE MECHANISMS THAT ORIGINATE CRITICAL SOCIAL PROBLEMS LIKE ANEUPLOIDY AND INFERTILITY. IN THIS GRANT PROPOSAL, WE WILL FOCUS ON TWO ASPECTS THAT ARISE FROM OUR PREVIOUS STUDIES: AIM 1. TO STUDY THE FUNCTION OF TRIP13 IN MEIOTIC PROPHASE. TRIP13 IS A MASTER REGULATOR OF THE MEIOTIC CELL CYCLE, CONTROLLING DSB REPAIR, CHROMOSOME AXIS FORMATION, DESYNAPSIS, MSUC, AND THE SPINDLE ASSEMBLY CHECKPOINT. TRIP13’S INVOLVEMENT IN THESE EVENTS IS THOUGHT TO BE DONE BY REMODELING HORMA DOMAIN PROTEINS. HOWEVER, IN OUR PREVIOUS GRANT, WE FOUND EVIDENCE THAT THE ATPASE FUNCTION OF TRIP13 IS DISPENSABLE TO PROMOTE THE LOADING OF RAD51 ONTO RESECTED BREAKS, IMPLYING THAT TRIP13 MAY HAVE UNEXPECTED SCAFFOLDING FUNCTIONS. THIS PROPOSAL WILL USE GENETIC, PROTEOMIC, GENOMIC, AND CELL BIOLOGY TOOLS TO UNCOVER TRIP13 SCAFFOLDING FUNCTIONS IN MEIOSIS. AIM 2. TO REVEAL GENETIC DETERMINANTS OF THE OVARIAN RESERVE AND TREATMENTS TO PROTECT THE FOLLICLE POOL. IN OUR PREVIOUS GRANT, WE UNCOVER 290 GENOMIC LOCI THAT DETERMINE THE AGE OF NATURAL MENOPAUSE. IN THIS PROPOSAL, WE WILL REVEAL MORE GENETIC DETERMINANTS OF THE OVARIAN RESERVE BY PERFORMING A FUNCTIONAL ANALYSIS OF FOLLICULOGENESIS ON TWO MUTANT MOUSE MODELS, SECISBP2 CKO AND BEND2-/-, THAT SHOWED FERTILITY ISSUES. OUR PREVIOUS GRANT ALSO FOUND THAT ANTIOXIDANTS CAN PROTECT THE OVARIAN RESERVE. IN THIS PROPOSAL, WE WILL KEEP EXPLORING USING SKQ1 AS A NOVEL TREATMENT TO PROTECT THE OVARIAN RESERVE FROM THE EFFECTS OF AGING. THE ACCOMPLISHMENT OF THESE OBJECTIVES WILL INCREASE OUR UNDERSTANDING OF HOW MEIOTIC RECOMBINATION OCCURS IN MAMMALS AND WILL ALLOW US TO BETTER UNDERSTAND HOW THE OVARIAN RESERVE IS MAINTAINED. THE LEARNINGS FROM THIS PROPOSAL HAVE THE LONG-TERM POTENTIAL TO IMPROVE THE DIAGNOSIS AND TREATMENT OF HUMAN INFERTILITY AND ANEUPLOIDY, AS PROVEN BY OUR FINDING THAT TREATMENT WITH SKQ1 CAN PROTECT THE OVARIAN RESERVE. SO, THIS RESEARCH HAS THE POTENTIAL TO BE APPLIED TO SOLVING CRUCIAL HUMAN HEALTH ISSUES, SUCH AS INFERTILITY AND ANEUPLOIDY.