A GFP trap study uncovers the functions of Gilgamesh protein kinase in Drosophila melanogaster spermatogenesis

Abstract

The function of the gene gilgamesh (89B9-12) encoding a casein kinase in Drosophila spermatogenesis was studied. The chimeric Gilgamesh-GFP protein in spermatocytes is cortically located. In the polar and apolar spermatocytes, it concentrates at the terminal ends of the fusome, the organelle that passes through the system of ring canals of the spermatocyte cyst. At the stage of spermatid elongation, the protein associates with the nucleus. A spot of the highest Gilgamesh-GFP concentration in the nucleus co-localizes with gamma-tubulin in the basal body. At later stages, Gilgamesh is localized to the individualization complex (IC), leaving the nuclei somewhat before the IC investment cones, as detected by actin binding. The sterile mutation due to the gilgamesh gene leads to the phenotype of scattered nuclei and altered structure of actin cones in the individualizing spermatid cyst. Ultrastructural evidence confirmed defective spermatid individualization due to the mutation. The phylogenetic origin of the protein, and the connection between vesicular trafficking and spermatid individualization, are discussed.

Novel Regulators of Planar Cell Polarity: A Genetic Analysis in Drosophila

“…The molecular nature and features of these new PCP regulatory genes ranged from kinases, phosphatases, enzymes required for lipid biosynthesis or modification, to proteins involved in substrate degradation or modification. Among the kinases, CG7004 (four wheel drive/fwd) encodes a PI4kinaseß, which has been shown to be required for male germ-line development (Polevoy et al 2009), and CG6963 (gilgamesh/gish), a casein kinase1g, known to be involved in many processes including Wnt signaling (Davidson et al 2005), glial cell migration (Hummel et al 2002), and spermatogenesis (Nerusheva et al 2009). Phosphatases of the PAP2 family, CG11426 and CG11438, were also identified.…”

Separating from the pack: Molecular mechanisms ofDrosophilaspermatid individualization

“…32 The microtubule cytoskeleton, as well as the actin cytoskeleton, seems to be important for individualization. Loss of the microtubule binding protein Abnormal Spindle (Asp) results in many spermatogenesis defects, including failed individualization.…”

Gilgamesh is required for the maintenance of germline stem cells in Drosophila testis

“…Previous study has reported that gish mutant germ cells contain abnormal actin cones in individualizing spermatid cysts 15 , this result implies that gish possibly affects the F-actin-mediated cell adhesion junctions. To explore whether the gish mutant GSCs lose adhesion to the hub, we visualized F-actin with phalloidin 15 and labeled GSCs with anti-Vasa antibody 17 .…”

“…We isolated a line with a P-element insertion in the third chromosome 15 , P{PZ} gish 04895 , which resulted in small testis and reduction in germ-cell number in homozygous mutant males. To thoroughly analyze the behavior of germ cells in gish 04895 mutant, we used anti-Fas III and anti-Vasa antibodies to visualize hub and germ cells 17, 18 , respectively (Fig.…”

“…To explore whether the gish mutant GSCs lose adhesion to the hub, we visualized F-actin with phalloidin 15 and labeled GSCs with anti-Vasa antibody 17 . We found that there was no difference in F-actin-based GSCs adhesion to hub cells between wild-type control and gish KG03891 / gish MI08417 mutant testes (n > 80) at day 14 after eclosion (Supplementary Fig.…”