Cloning And Function Of Mouse Dynein Axonemal Intermediate Chain 2

Reproductive development is a complex process. Any defects during this process will due to infertility and sterility. Thus, investigation of the mechanisms and related genes become hot topic for researchers. In this paper, we selected a partial cDNA fragment by differential display reverse-transcription PCR using total RNA extracted from mouse 5-day and 10-day ovaries, and its open reading frame was obtained by rapid amplification of cDNA ends. Sequencing showed that the fragment is the gene named mouse dynein axonemal intermediate chain 2 (Dnaic2), whose product is homologous protein of human DNAI2 protein, a component of axonemal dynein complex that function in cilia or flagellar. Dnaic2 has an 87% homology with human DNAI2, a candidate gene for primary ciliary dyskinesia which can cause lung inflammation, male sterility or female subfertility. Northern and western analyses indicate that Dnaic2 produces an approximately 3 kb mRNA that is translated into an approximately 70 kDa protein. The mRNA is predominantly expressed in mouse ovary, testis, lung and oviduct, and displayed a development-depended profile in mouse ovary. Immunofluorescence histochemistry analysis showed that Dnaic2 protein was localized near the surface of the oocyte of only secondary and antral follicles but not primordial and primary ones. Besides that, Dnaic2 protein was also expressed in epithelial cells of oviduct, some male germ cells and sperm (especially in head and middle piece). Dnaic2-overexpressed mice showed similar symptoms with human PCD patients. Some Dnaic2-overexpressed mice (Line1) die at only about 20 days after born dut to the severe lung inflammation. Adult transgenic mice were infertility or subfertility, due to the abnormal sperm as well as absence of dynein arm and some microtubules in axoneme of sperm that caused asthenospermia in male mice, or pathological changes of tunica mucosa in oviduct, increase of atretic follicles and decrease of normal Graaffian follicles in female ones. In addition, our research showed that Dnaic2 protein had interaction with LC8 and Stat3. It could promote the phosphorylation of Stat3, even though it did not change the expression of LC8 and Stat3. The sustained phosphorylation of Stat3 was found in testis, ovary and lung from Dnaic2-overexpressed mice, suggesting that Dnaic2 plays roles in oogenesis or spermatogenesis through Stat3 and LC8.