THYMOSIN ALPHA-1 AND FA-1 MONOCLONAL-ANTIBODY AFFECT MURINE PREIMPLANTATION EMBRYO DEVELOPMENT BY MODULATING PROTEIN-PHOSPHORYLATION

The effects of thymosin alpha 1 (T alpha 1) and FA-1 monoclonal antibo dy (anti-FA-1 mAb) on murine preimplantation embryonic development wer e investigated by performing 2-cell embryo bioassay and by studying ov a/embryos protein phosphorylation pattern (by P-32 metabolic labeling and by in vitro kinase assay) and protein synthesis (by in vitro [S-35 ]methionine labeling). Tal treatment (0.1, 0.5 and 5 ng/100 mu l) sign ificantly increased blastulation rates (P < 0.01), blastocyst hatching rate (P < 0.0001), blastocyst diameter (P < 0.001) and number of cell s per blastocyst (P < 0.0001) of the in vitro cultured 2-cell stage em bryos. Anti-FA-1 mAb reduced blastulation rates (P < 0.001) primarily due to an arrest of development at morula stage. In vitro metabolic la beling of murine ova/embryos showed P-32 incorporation into 4 major pr otein bands of murine ova (M(r) 125, 90, 68 and 31 kDa, respectively), 7 protein bands of 2-cell (M(r) 90, 68 and 31; and 145, 52, 38 and 32 kDa, respectively), 10 protein bands of morula (M(r) 150, 110, 92, 82 , 70, 54, 39, 34, 30 and 29 kDa, respectively), and 15 protein bands o f blastocyst (150, 110, 92, 70, 68, 54, 39, 34 and 30; and 131, 105, 5 2, 44, 43 and 33 kDa, respectively) stage embryos. T alpha 1 treatment (0.1-0.5 ng/100 pi) resulted in a general increase in P-32 labeling i n all proteins of 2-cell, morula and blastocyst stage embryos. Anti-FA -1 mAb completely blocked P-32 labeling of various proteins of murine ova, 2-cell, morula and blastocyst stage embryos, whereas control mous e myeloma IgG did not affect phosphorylation of these proteins. In vit ro kinase assay performed directly on various ova/embryos extracts rev ealed 6 phosphoproteins (M(r) 105, 82, 55, 38, 34 and 33 kDa, respecti vely) that were common to ova and 2-cell embryos, besides a 43 kDa pro tein detected only in the ova extract. Of these phosphoproteins, T alp ha 1 treatment specifically enhanced whereas anti-FA-1 mAb inhibited a utophosphorylation of a 55 kDa protein of 2-cell embryos. Similarly, T alpha 1 treatment enhanced 6 phosphoproteins of morula (M(r) 102, 60, 58, 49, 35 and 32 kDa, respectively) and 4 phosphoproteins of blastoc yst (M(r) 102, 60, 49 and 35 kDa, respectively) stage embryo extracts in the kinase assay. In [S-35]methionine labeling experiments, T alpha 1 treatment did not affect labeling of any of the 5 proteins (M(r) 17 0, 95, 86, 62 and 42 kDa, respectively) of 2-cell embryos, however, it enhanced labeling of 1 protein band of ova (46 kDa), 7 proteins of mo rula (M(r) 95, 86, 70, 43, 42, 39 and 35 kDa, respectively) and 9 prot eins of blastocyst (M(r) 95, 86, 70, 43, 42, 39 and 35; and 51 and 33 kDa, respectively) stage embryos. Anti-FA-1 mAb did not affect S-35 la beling of murine ova and 2-cell, morula or blastocyst proteins compare d to control myeloma IgG. These results suggest that T alpha 1 enhance murine preimplantation embryonic development by modulating protein ph osphorylation pattern as well as protein synthesis. On the other hand, anti-FA-1 mAb inhibit embryonic development by modulating protein pho sphorylation pattern without affecting protein synthesis.