Spindle positioning in human cells relies on proper centriole formation and on the microcephaly proteins CPAP and STIL

Abstract

SummaryPatients with MCPH (autosomal recessive primary microcephaly) exhibit impaired brain development, presumably due to the compromised function of neuronal progenitors. Seven MCPH loci have been identified, including one that encodes centrosome protein 4.1 associated protein (CPAP; also known as centromere protein J, CENPJ). CPAP is a large coiled-coil protein enriched at the centrosome, a structure that comprises two centrioles and surrounding pericentriolar material (PCM). CPAP depletion impairs centriole formation, whereas CPAP overexpression results in overly long centrioles. The mechanisms by which CPAP MCPH patient mutations affect brain development are not clear. Here, we identify CPAP protein domains crucial for its centriolar localization, as well as for the elongation and the formation of centrioles. Furthermore, we demonstrate that conditions that resemble CPAP MCPH patient mutations compromise centriole formation in tissue culture cells. Using adhesive micropatterns, we reveal that such defects correlate with a randomization of spindle position. Moreover, we demonstrate that the MCPH protein SCL/TAL1 interrupting locus (STIL) is also essential for centriole formation and for proper spindle position. Our findings are compatible with the notion that mutations in CPAP and STIL cause MCPH because of aberrant spindle positioning in progenitor cells during brain development.

Centrobin-mediated Regulation of the Centrosomal Protein 4.1-associated Protein (CPAP) Level Limits Centriole Length during Elongation Stage

“…In summary, we report the identification of centrobin as an upstream regulator of CPAP, a centrosomal protein with crucial role in centriole assembly, spindle orientation, brain development, and ciliogenesis (4,17,27,35,41,64). Of clinical importance, patients with microcephaly and Seckel syndrome were found to have mutations in this gene (41,42).…”

“…They also have pivotal roles in organizing an accurate bipolar spindle during normal and asymmetric cell division, spindle orientation and positioning, biogenesis of the cilia and flagella, and immune response (1)(2)(3)(4)(5)(6).…”

The Centrosome and Its Duplication Cycle

“…Neuroprogenitors depleted of ASPM fail to orient the mitotic spindle perpendicular to the ventricular surface of the neuroepithelium giving asymmetric, rather than symmetric, divisions (Fish et al 2006). Mutations in CPAP (MCPH6) and STIL (MCPH7) also affect spindle orientation (Kitagawa et al 2011b;Brito et al 2012). Other genes for centrosomal proteins that are mutated in microcephaly include the CNN homolog, CDK5RAP2 (MCPH3), required for centrosome maturation and DNA damage-induced G 2 arrest (Barr et al 2010;Lizarraga et al 2010), and CEP63 with its partner Cep152, which participate in centriole assembly (Sir et al 2011).…”

The role of mitotic kinases in coupling the centrosome cycle with the assembly of the mitotic spindle

“…Basis of the ninefold symmetry of the cartwheel structure Gudi et al, 2011;Kitagawa et al, 2011b;van Breugel et al, 2011 Cep152 Recruits Plk4 and SAS6 for the initiation of centriole duplication Cizmecioglu et al, 2010;Hatch et al, 2010;Kim et al, 2013 Cep192 Cooperates with Cep152 to recruit Plk4 to the centrosome Kim et al, 2013;Sonnen et al, 2013 Plk4 Multiple roles; see the main text Bettencourt-Dias et al, 2005;Habedanck et al, 2005;Kleylein-Sohn et al, 2007;Puklowski et al, 2011;Rogers et al, 2009;Swallow et al, 2005 Cep135 Stabilizes the cartwheel structure by interacting with SAS6 and CPAP Cottee et al, 2013;Hatzopoulos et al, 2013;Lin et al, 2013a;Roque et al, 2012 STIL Establishes the linkage between centriolar scaffold and microtubules Arquint and Nigg, 2014;Kitagawa et al, 2011a;Lin et al, 2013b Promoting procentriole elongation and determining ...…”