Murine germ cell-specific disruption of Ift172 causes defects in spermiogenesis and male fertility
REPRODUCTION
Authors: Zhang, Shiyang; Liu, Yunhao; Huang, Qian; Yuan, Shuo; Liu, Hong; Shi, Lin; Yap, Yi Tian; Li, Wei; Zhen, Jingkai; Zhang, Ling; Hess, Rex A.; Zhang, Zhibing
Abstract
Intraflagellar transport (IFT) is a conserved mechanism essential for the assembly and maintenance of most eukaryotic cilia and flagella. IFT172 is a component of the IFT complex. Global disruption of mouse Ift172 gene caused typical phenotypes of ciliopathy. Mouse Ift172 gene appears to translate two major proteins; the full-length protein is highly expressed in the tissues enriched in cilia and the smaller 130 kDa one is only abundant in the testis. In male germ cells, IFT172 is highly expressed in the manchette of elongating spermatids. A germ cell-specific Ift172 mutant mice were generated, and the mutant mice did not show gross abnormalities. There was no difference in testis/body weight between the control and mutant mice, but more than half of the adult homozygous mutant males were infertile and associated with abnormally developed germ cells in the spermiogenesis phase. The cauda epididymides in mutant mice contained less developed sperm that showed significantly reduced motility, and these sperm had multiple defects in ultrastructure and bent tails. In the mutant mice, testicular expression levels of some IFT components, including IFT20, IFT27, IFT74, IFT81 and IFT140, and a central apparatus protein SPAG16L were not changed. However, expression levels of ODF2, a component of the outer dense fiber, and AKAP4, a component of fibrous sheath, and two IFT components IFT25 and IFT57 were dramatically reduced. Our findings demonstrate that IFT172 is essential for normal male fertility and spermiogenesis in mice, probably by modulating specific IFT proteins and transporting/assembling unique accessory structural proteins into spermatozoa.
ODF2 maintains centrosome cohesion by restricting beta-catenin accumulation
JOURNAL OF CELL SCIENCE
Authors: Yang, Kefei; Tylkowski, Marco Andreas; Hueber, Daniela; Contreras, Constanza Tapia; Hoyer-Fender, Sigrid
Abstract
The centrosome, as the main microtubule-organizing center, safeguards chromosome segregation by supporting the bipolar spindle. Centrosome aberrations are causally related to chromosome segregation disorders, both characterizing cancer cells. Thus, a restriction to only having one centrosome per cell and cell cycle-dependent duplication of the centrosome is mandatory. Duplicated centrosomes remain physically connected, in order to function as a single entity, until onset of mitosis when centrosome disjunction is licensed by disassembly of linker proteins and accumulation of beta-catenin. The crucial role beta-catenin plays in centrosome disjunction inevitably demands for restricting its premature accumulation. ODF2 (also known as cenexin) is an essential centrosomal component, but its relevance for the interphase centrosome has not been elucidated. We show here that ODF2 plays a central role in centrosome cohesion. Depletion of ODF2 induces premature centrosome splitting and formation of tripolar spindles that are likely caused by the observed accumulation of centrosomal beta-catenin. Our data collectively indicate that ODF2 restricts beta-catenin accumulation at the centrosome, thus preventing premature centrosome disjunction.