Drosophila Spd-2 Recruits PCM to the Sperm Centriole, but Is Dispensable for Centriole Duplication

Abstract

SummaryIn C. elegans, genome-wide screens have identified just five essential centriole-duplication factors: SPD-2, ZYG-1, SAS-5, SAS-6, and SAS-4 [1–8]. These proteins are widely believed to comprise a conserved core duplication module [3, 9–14]. In worm embryos, SPD-2 is the most upstream component of this module, and it is also essential for pericentriolar material (PCM) recruitment to the centrioles [1, 4, 15, 16]. Here, we show that Drosophila Spd-2 (DSpd-2) is a component of both the centrioles and the PCM and has a role in recruiting PCM to the centrioles. DSpd-2 appears not, however, to be essential for centriole duplication in somatic cells. Moreover, PCM recruitment in DSpd-2 mutant somatic cells is only partially compromised, and mitosis appears unperturbed. In contrast, DSpd-2 is essential for proper PCM recruitment to the fertilizing sperm centriole, and hence for microtubule nucleation and pronuclear fusion. DSpd-2 therefore appears to have a particularly important role in recruiting PCM to the sperm centriole. We speculate that the SPD-2 family of proteins might only be absolutely essential for the recruitment of centriole duplication factors and PCM to the centriole(s) that enter the egg with the fertilizing sperm.

The Centrosome and Its Duplication Cycle

“…This echoes the finding of the dependency of ZYG-1 recruitment on SPD-2 in C. elegans. However, in Drosophila, Spd-2 barely plays any role in centriole assembly but is instead required for PCM recruitment on mitotic entry (Dix and Raff 2007;Giansanti et al 2008). In Planarians where the canonical centriole duplication pathway was abandoned during evolution and centrioles are only assembled in terminally differentiating ciliated cells through an acentriolar pathway, Spd-2/Cep192 along with CNN/CDK5RAP2 and Nek2 are all absent from the genome (Azimzadeh et al 2012).…”

Exploring the evolutionary history of centrosomes

“…SPD-2/ Cep192 proteins are recruited in the immediate vicinity of the centrioles and play a key role in organizing the PCM by recruiting CNN/CDK5RAP2 and microtubule-nucleating complexes [3,4,119]. Caenorhabidtis elegans and human SPD-2 homologues are also required for centriole duplication, but possibly indirectly through their ability to recruit PCM, as Drosophila SPD-2 is dispensable for centriole duplication [119][120][121]. Remarkably, an SPD-2 orthologue is encoded in the Dictyostelium genome and localizes to the corona that surrounds the NAB, which is functionally equivalent to the PCM [40].…”

DrosophilaBld10 Is a Centriolar Protein That Regulates Centriole, Basal Body, and Motile Cilium Assembly

“…20, May 15, 2009with the antibody directed against the C-terminus (see Figure 4C). Because bld10 f01951 and bld10 c04199 are both predicted to produce C-terminal truncations, we also examined whether the antibody directed against the N-terminus of Bld10 (see Figure 1B) could detect a mutant protein localized at the basal bodies.…”

“…In flies, mutations in these genes abolish centrosome and cilium/flagellum assembly (except mutations in ana1 and ana2, which have not been described yet). Additional centriole/ basal body proteins including Spd-2, Drosophila pericentrin-like protein (D-PLP)/CP309, and uncoordinated (UNC) function in pericentriolar material (PCM) recruitment to centrosomes and/or the assembly of cilia and flagella Kawaguchi and Zheng, 2004;Martinez-Campos et al, 2004;Dix and Raff, 2007;Giansanti et al, 2008). Identification of the complete set of centriole components is necessary to define their individual and cooperative roles in the assembly and function of centrioles and cilia.…”