Abstract
ABSTRACTCentrosomes comprise a pair of centrioles surrounded by a matrix of pericentriolar material (PCM). In vertebrate cells, Pericentrin plays an important part in mitotic PCM assembly, but the Drosophila Pericentrin-like protein (PLP) appears to have a more minor role in mitotic fly cells. Here we investigate the function of PLP during the rapid mitotic cycles of the early Drosophila embryo. Unexpectedly, we find that PLP is specifically enriched in the outer-most regions of the PCM, where it largely co-localizes with the PCM scaffold protein Cnn. In the absence of PLP the outer PCM appears to be structurally weakened, and it rapidly disperses along the centrosomal microtubules (MTs). As a result, centrosomal MTs are subtly disorganized in embryos lacking PLP, although mitosis is largely unperturbed and these embryos develop and hatch at near-normal rates. Y2H analysis reveals that PLP can potentially form multiple interactions with itself and with the PCM recruiting proteins Asl, Spd-2 and Cnn. A deletion analysis suggests that PLP participates in a complex network of interactions that ultimately help to strengthen the PCM.
Highlights
Centrosomes are the major microtubule (MT) organizing centers (MTOCs) in many eukaryotic cells and they play an important part in many cell processes, including establishing and maintaining cell polarity and cell division (Bornens, 2012; Nigg and Raff, 2009)
The mother centriole appears to recruit a small amount of pericentriolar material (PCM) that is highly organized (Fu and Glover, 2012; Lawo et al, 2012; Mennella et al, 2012; Sonnen et al, 2012): in particular the centriole and PCM protein Pericentrin – the Pericentrin-like-protein (PLP or CP309) in flies (Kawaguchi and Zheng, 2004; MartinezCampos et al, 2004) – exhibits a stereotypical organization, with its C-terminal PACT domain in close contact with the mother centriole and its N-terminus extending outwards away from the centriole
Most other PCM components lie within the region bounded by the extended Pericentrin/Pericentrin-like protein (PLP) molecules and, in fly cultured cells, the depletion of PLP severely disrupts the recruitment of the other interphase PCM components (Mennella et al, 2012)
Summary
Centrosomes are the major microtubule (MT) organizing centers (MTOCs) in many eukaryotic cells and they play an important part in many cell processes, including establishing and maintaining cell polarity and cell division (Bornens, 2012; Nigg and Raff, 2009). RESULTS AND DISCUSSION PLP is concentrated at centrioles but is enriched in the outer regions of the PCM We previously showed that antibodies raised against PLP predominantly stain centrioles in Drosophila somatic cells; a GFP-fusion to the 226 aa C-terminal PACT domain was strongly concentrated in centrioles, but was more weakly detectable in the PCM in early embryos (Martinez-Campos et al, 2004).
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