Ono Kanako, Ono Shoichiro
Department of Pathology, Emory University, Atlanta, Georgia 30322, USA.
Mol Biol Cell. 2004 Jun;15(6):2782-93. doi: 10.1091/mbc.e04-03-0179. Epub 2004 Apr 2.
Ovulation in the nematode Caenorhabditis elegans is coordinated by interactions between the somatic gonad and germ cells. Myoepithelial sheath cells of the proximal ovary are smooth muscle-like cells, but the regulatory mechanism of their contraction is unknown. We show that contraction of the ovarian muscle requires tropomyosin and troponin, which are generally major actin-linked regulators of contraction of striated muscle. RNA interference of tropomyosin or troponin C caused sterility by inhibiting ovarian contraction that is required for expelling mature oocytes into the spermatheca where fertilization takes place, thus causing accumulation of endomitotic oocytes in the ovary. Tropomyosin and troponin C were associated with actin filaments in the myoepithelial sheath, and the association of troponin C with actin was dependent on tropomyosin. A mutation in the actin depolymerizing factor/cofilin gene suppressed the ovulation defects by RNA interference of tropomyosin or troponin C. These results strongly suggest that tropomyosin and troponin are the actin-linked regulators for contraction of ovarian muscle in the C. elegans reproductive system.
线虫秀丽隐杆线虫的排卵是由体细胞性腺和生殖细胞之间的相互作用协调的。近端卵巢的肌上皮鞘细胞是平滑肌样细胞，但其收缩的调节机制尚不清楚。我们发现卵巢肌肉的收缩需要原肌球蛋白和肌钙蛋白，它们通常是横纹肌收缩的主要肌动蛋白连接调节因子。对原肌球蛋白或肌钙蛋白C进行RNA干扰会抑制卵巢收缩，从而导致不育，而卵巢收缩是将成熟卵母细胞排入受精发生的受精囊所必需的，进而导致卵巢中多线期卵母细胞的积累。原肌球蛋白和肌钙蛋白C与肌上皮鞘中的肌动蛋白丝相关，并且肌钙蛋白C与肌动蛋白的结合依赖于原肌球蛋白。肌动蛋白解聚因子/丝切蛋白基因的突变通过对原肌球蛋白或肌钙蛋白C进行RNA干扰来抑制排卵缺陷。这些结果有力地表明，原肌球蛋白和肌钙蛋白是秀丽隐杆线虫生殖系统中卵巢肌肉收缩的肌动蛋白连接调节因子。
