TY  - JOUR
TI  - Complement component C3 functions as an embryotrophic factor in early postimplantation rat embryos 
AU  - Usami, Makoto
AU  - Mitsunaga, Katsuyoshi
AU  - Miyajima, Atsuko
AU  - Sunouchi, Momoko
AU  - Doi, Osamu
T2  - The International Journal of Developmental Biology
AB  - A presumed embryotrophic factor for early postimplantation rat embryos, partially purified from rat serum, was identified as complement component C3 (C3), the central component of the complement system, by sequence analysis of its N-terminal. Purified rat C3 showed embryotrophic activity for rat embryos cultured from day 9.5 of gestation for 48 h in the culture medium composed of rabbit serum. The maximum embryotrophic activity of C3 was observed around 0.5 mg/ml, a level which is lower than rat serum C3 levels. In the culture medium composed of rat serum, cultured rat embryos selectively consumed C3, and C3-depletion by cobra venom factor affected embryonic growth. Inactivation of the internal thiolester bond of C3, the critical functional site for its activity in the complement system, by methylamine had no effects on its embryotrophic activity. Purified rabbit C3 had only weak embryotrophic activity for cultured rat embryos, suggesting species specificity of the embryotrophic activity of C3. Immunochemical analyses showed the specific presence of C3 on the visceral yolk sac, but not on the embryo proper of day 9.5 or 10.5 rat embryos both in utero and in vitro. In analysis using fluorescein-labeled rat C3, unfragmented C3s bound to the visceral yolk sac stronger than C3b, the primary active fragment of C3 in the complement system. These results indicate that C3, which has always been considered to be detrimental to embryos, functions as an embryotrophic factor by novel mechanisms probably through the visceral yolk sac. The present study thus provides new insights into functions of C3 and postimplantation embryonic growth.
PY  - 2010
DO  - 10.1387/ijdb.092993mu
VL  - 54
IS  - 8-9
SP  - 1277
EP  - 1285
J2  - Int. J. Dev. Biol.
LA  - en
SN  - 0214-6282
SN  - 1696-3547
UR  - https://ijdb.ehu.eus/article/092993mu
Y2  - 2024/05/06/19:05:26
ER  -