spag16, an axonemal central apparatus gene, encodes a male germ cell nuclear speckle protein that regulates spag16 mrna expressionspag16,axonemal中央装置基因,编码一个男性生殖细胞的核散斑蛋白调节spag16 mrna的表达.pdf

Spag16, an Axonemal Central Apparatus Gene, Encodes a Male Germ Cell Nuclear Speckle Protein that Regulates SPAG16 mRNA Expression 1,2 3 4 2 1,2 David R. Nagarkatti-Gude , Ruth Jaimez , Scott C. Henderson , Maria E. Teves , Zhibing Zhang , Jerome F. Strauss III1,2* 1 Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America, 2 Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, Virginia, United States of America, 3 Center for Research on Reproduction and Women’s Health, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America, 4 Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, United States of America Abstract Spag16 is the murine orthologue of Chlamydomonas reinhardtii PF20, a protein known to be essential to the structure and function of the ‘‘9+2’’ axoneme. In Chlamydomonas, the PF20 gene encodes a single protein present in the central pair of the axoneme. Loss of PF20 prevents central pair assembly/integrity and results in flagellar paralysis. Here we demonstrate that the murine Spag16 gene encodes two proteins: 71 kDa SPAG16L, which is found in all murine cells with motile cilia or flagella, and 35 kDa SPAG16S, representing the C terminus of SPAG16L, which is expressed only in male germ cells, and is predominantly found in specific regions within the nucleus that also contain SC35, a known marker of nuclear speckles enriched in pre-mRNA splicing factors. SPAG16S expression precedes expression of SPAG16L. Mice homozygous for a knockout of SPAG16L alone are infertile, but show