Introduction 1875 1876 1901 1901 1891 Definition of the centrosome and its key functions 2002 1984 2004 1 Nu M A 2003 2002 2 Fig. 1 A typical mammalian centrosome is composed of two centrioles surrounded by a meshwork of a proteins embedded in matrix called the pericentriolar material (PCM). Gamma-tubulin and the gamma-tubulin ring complex that nucleate microtubules along with associated proteins are embedded in the PCM. Highlighted in this diagram are two centrosomal complexes, the microtubule nucleating complex and the microtubule anchoring complex  Fig. 2 a white circles black circles b  1999 1999 2003 Drosophila 1999 Xenopus 1999 2004 2006 Taken together, the centrosome is a truly central and main cellular station that directs, coordinates, and regulates most cellular functions either directly or indirectly through its microtubule organizing capabilities. Centrosome proteins and their specific functions 1983 2003 2004 2006 2004 structural proteins regulatory molecules heat shock proteins 1998 centrosome scaffolds 1996 2000a 2004 Centrosome proteins that have been studied more fully in various cell systems include γ-tubulin, pericentrin, centrin, and NuMA. Gamma-tubulin 1989 2003 1999 2000 1990 1992 1995 2002 1999 2000 2001 1995 1995 1999 2000 2003 2001 1998 1998 1998 1998 1994 2003 2000 2004 2003 2002 2002 2002 A cell cycle-dependent regulation of γ-TuRC is thought to account for differences between interphase and mitotic microtubule structure formations and activities. In interphase γ-TuRC nucleates fewer but longer microtubules while in mitosis, more γ-TuRC is associated with the centrosome, which is part of the centrosome maturation process that takes place from interphase to mitosis (discussed below). Mitotic microtubules are shorter, larger in number, and highly dynamic. They are regulated by a number of cell cycle-specific proteins that participate in centrosome regulation such as the small GTPase Ran, Aurora A kinase, polo-like kinases and others. Pericentrin 1994 1998 2000 2000 1998 2000 Centrins 2+ 2002 2004 1996 1995 2001 2005 2002 NuMA Nu M A 2006 2007 2000 1999 2001 2002 Centrosome cycle within the cell cycle 3 1901 3 4 3 3 3 Fig. 3 a arrows c arrows e arrows g arrows b d f h blue green b d red f h 2000a  Fig. 4 a c d red b e green b 2000b  4 4 4 4 2000 2004 2001 2002 Polo like kinases 2001a b c d 2002 2002 2003 2003 1993 2001 2002 2002 2001 docking station Phosphorylation and posttranslational modifications 2004 Centrosome duplication 2003 2004 Xenopus 1999 1999 1999 1999 2002 1995 1990 1995 1999 1999 Xenopus 1990 1995 5 Fig. 5 a b c d e f g shaded yellow black shaded orange black rods black 2007  Centrosome maturation into mitotic centrosomes centrosome maturation 1999 1999 2004 1989 1997 2003 1999 1995 1996 1998 2003 2006 2007 1997 1998 2004 2004 1998 2000 2001 1997 2000 2001 2005 2006 2000 2007 2003 Cdc20 2000 1999 2000 Microtubule motor proteins 2002 1999 2003 2004 1978 1998 1999 2003 Supernumerary centrosomes: role in genomic instability and cancer 1914 1999 2000 1998 2003 1999 1998a b 1999a b 2000a b c 1998 2004 2002 2003 1998 2000c 1999 2004 2002 1999 Aurora kinases play central roles in the mitotic process and cell division and Aurora A has been implicated in centrosome amplification in breast cancer. Aurora A localizes to centrosomes and overexpression of Aurora A causes multipolar mitotic spindles and is implicated in early development of mammary tumors. 2004 2000 aging 2000 1990 1990 2000 Centrosome-independent pathways and non-centrosomal microtubule arrays 2002 2005 2004 2000 2001 2000 2000 2001 2001 1998 1999 1999 1999 1993 2000 1996 1998 1998 2001 1995 2002 2001 2004 2000 2002 Centrosome abnormalities and mitotic cell death 2000d 2000d 6 1991 2002 2004 2000 1995 1996 1993 1978 1991 1990 1993 1997 Drosophila 1999a 2005 2007 2001 2002 Fig. 6 a b red a green b b red 2000d  1983 2000a b 2004 2001 2000a b 1996 1999 1999 1999 2000 2003 1999 1998 2003 2000 2008 2002 Centrosomes in reproduction including fertilization and somatic cell nuclear transfer (SCNT) 1901 1914 7 1986 1987 2005 2006 2007 2005 2006 2007 1994 1996 Fig. 7 green red  Centrosome remodeling after nuclear transfer: communication between embryonic and somatic cells 2000 2007 2005 2007 2003 2007 2007 1998 2000a b 2007 2007 1997 1998 2004 Taken together, studies of centrosomes in reconstructed embryos will provide new avenues to obtain information on centrosomal regulation by cytoplasmic factors. Concluding remarks and future directions 2005 Drosophila Toxoplasma 2006 2004 2004