FUNCTION OF THE ter MUTATION AND MOLECULAR CHARACTERISTCS OF A NOVEL PRIMORDIAL GERM CELL GROWTH FACTOR (TERF) IN MICE

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Congenic mice bearing the ter (teratoma, Chr. 18) mutation that induces the deficiency of primordial germ cells (PGCs) in ter/ter males and females can serve as an animal model of congenital sterility. PGC deficiency occurs in the reconstituted fetal testes containing +/+ PGCs and ter/ter fetal testicular somatic cells. The number of +/+ PGCs that were co-cultured with own somatic cells in the conditioned media (CM) obtained from +/+ and +/ter fetal testicular somatic cells was increased but it was decreased in ter/ter CM. These data suggested a possibility of a novel ter-related growth factor, TERF. In this project the function of the ter gene and molecular characteristics of TERF were analyzed using PGC culture systems and the ter congenic mice. Results obtained were showed below.1. Both +/+ and ter/ter PGCs survived and proliferated on +/+ fetal Sertoli cells co-cultured, but those were degenerated by TUNEL-positive apoptosis on the ter/ter ones, whereas their DNA synthesis occurred … More normally. 2. Administration of +/+ CM from fetal ovarian and testicular somatic cells inhibited apoptosis in +/+ PGCs, but ter/ter CM did not. Both CM supported DNA synthesis of PGCs. 3. Administration of +/+ CM can not inhibit apoptosis in PGCs co-cultured with the ter/ter somatic cells. 4. +/+CM contained heat labile and freeze-resistant protein like substance (m.w. > 30,000) supporting survival of PGCs but not somatic cells. ter/ter CM did not. 5. Several PGC growth factors and their receptors were expressed in ter/terfetal and adult testes as well as in +/+ ones. 6. Thus, it is concluded that a novel ter-related PGC growth factor (designated as TER Factor, TERF) with soluble and membrane-bounded types supports PGC survival by inhibiting apoptosis in PGCs through develdpmental stages and that it is produced by ovarian and testicular somatic cells. It is also concluded that ter/ter somatic cells produce a default type of TERF, resulting in apoptotic death in ter/terPGCs with normal survivability and proliferation ability and sterility of ter/termales and females. 7. We are cloning of the genes in the ter locus now. Less