Abstract
Primary microcephaly is a clinical phenotype in which the head circumference is significantly reduced at birth due to abnormal brain development, primarily at the cortical level. Despite the marked genetic heterogeneity, most primary microcephaly-linked genes converge on mitosis regulation. Two consanguineous families segregating the phenotype of severe primary microcephaly, spasticity and failure to thrive had overlapping autozygomes in which exome sequencing identified homozygous splicing variants in CIT that segregate with the phenotype within each family. CIT encodes citron, an effector of the Rho signaling that is required for cytokinesis specifically in proliferating neuroprogenitors, as well as for postnatal brain development. In agreement with the critical role assigned to the kinase domain in effecting these biological roles, we show that both splicing variants predict variable disruption of this domain. The striking phenotypic overlap between CIT-mutated individuals and the knockout mice and rats that are specifically deficient in the kinase domain supports the proposed causal link between CIT mutation and primary microcephaly in humans.
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Alazami AM, Patel N, Shamseldin HE, Anazi S, Al-Dosari MS, Alzahrani F, Hijazi H, Alshammari M, Aldahmesh MA, Salih MA (2015) Accelerating novel candidate gene discovery in neurogenetic disorders via whole-exome sequencing of prescreened multiplex consanguineous families. Cell Rep 10:148–161
Al-Dosari MS, Shaheen R, Colak D, Alkuraya FS (2010) Novel CENPJ mutation causes Seckel syndrome. J Med Genet 47:411–414
Alkuraya FS (2010a) Autozygome decoded. Genet Med 12:765–771
Alkuraya FS (2010b) Homozygosity mapping: one more tool in the clinical geneticist’s toolbox. Genet Med 12:236–239
Alkuraya FS (2012) Discovery of rare homozygous mutations from studies of consanguineous pedigrees. Curr Protoc Hum Genet. doi:10.1002/0471142905.hg0612s75
Alkuraya FS (2013) The application of next-generation sequencing in the autozygosity mapping of human recessive diseases. Hum Genet 132:1197–1211
Alkuraya FS (2015) Primordial dwarfism: an update. Curr Opin Endocrinol Diabetes Obes 22:55–64
Alkuraya FS (2016) Discovery of mutations for Mendelian disorders. Hum Genet 135(6):615–623
Alkuraya FS, Cai X, Emery C, Mochida GH, Al-Dosari MS, Felie JM, Hill RS, Barry BJ, Partlow JN, Gascon GG (2011) Human mutations in NDE1 cause extreme microcephaly with lissencephaly. Am J Hum Genet 88:536–547
Anazi S, Maddirevula S, Faqeih E, Alsedairy H, Alzahrani F, Shamseldin H, Patel N, Hashem M, Ibrahim N, Abdulwahab F (2016) Clinical genomics expands the morbid genome of intellectual disability and offers a high diagnostic yield. Mol Psychiatr. doi:10.1038/mp.2016.113
Barkovich A, Kuzniecky R, Jackson G, Guerrini R, Dobyns W (2005) A developmental and genetic classification for malformations of cortical development. Neurology 65:1873–1887
Bassi ZI, Audusseau M, Riparbelli MG, Callaini G, D’Avino PP (2013) Citron kinase controls a molecular network required for midbody formation in cytokinesis. Proc Natl Acad Sci 110:9782–9787
Camera P, Da Silva JS, Griffiths G, Giuffrida MG, Ferrara L, Schubert V, Imarisio S, Silengo L, Dotti CG, Di Cunto F (2003) Citron-N is a neuronal Rho-associated protein involved in Golgi organization through actin cytoskeleton regulation. Nat Cell Biol 5:1071–1078
Cogswell C, Sarkisian M, Leung V, Patel R, D’Mello S, LoTurco J (1998) A gene essential to brain growth and development maps to the distal arm of rat chromosome 12. Neurosci Lett 251:5–8
D’Avino PP, Savoian MS, Glover DM (2004) Mutations in sticky lead to defective organization of the contractile ring during cytokinesis and are enhanced by Rho and suppressed by Rac. J Cell Biol 166:61–71
Di Cunto F, Calautti E, Hsiao J, Ong L, Topley G, Turco E, Dotto GP (1998) Citron rho-interacting kinase, a novel tissue-specific ser/thr kinase encompassing the Rho-Rac-binding protein Citron. J Biol Chem 273:29706–29711
Di Cunto F, Imarisio S, Hirsch E, Broccoli V, Bulfone A, Migheli A, Atzori C, Turco E, Triolo R, Dotto GP (2000) Defective neurogenesis in citron kinase knockout mice by altered cytokinesis and massive apoptosis. Neuron 28:115–127
Eda M, Yonemura S, Kato T, Watanabe N, Ishizaki T, Madaule P, Narumiya S (2001) Rho-dependent transfer of Citron-kinase to the cleavage furrow of dividing cells. J Cell Sci 114:3273–3284
Filges I, Friedman JM (2015) Exome sequencing for gene discovery in lethal fetal disorders—harnessing the value of extreme phenotypes. Prenat Diagn 35:1005–1009
Filges I, Nosova E, Bruder E, Tercanli S, Townsend K, Gibson W, Röthlisberger B, Heinimann K, Hall J, Gregory-Evans C (2014) Exome sequencing identifies mutations in KIF14 as a novel cause of an autosomal recessive lethal fetal ciliopathy phenotype. Clin Genet 86:220–228
Fujikura K, Setsu T, Tanigaki K, Abe T, Kiyonari H, Terashima T, Sakisaka T (2013) Kif14 mutation causes severe brain malformation and hypomyelination. PLoS One 8:e53490
Furuyashiki T, Fujisawa K, Fujita A, Madaule P, Uchino S, Mishina M, Bito H, Narumiya S (1999) Citron, a Rho-target, interacts with PSD-95/SAP-90 at glutamatergic synapses in the thalamus. J Neurosci 19:109–118
Grossi M, Hiou-Feige A, Di Vignano AT, Calautti E, Ostano P, Lee S, Chiorino G, Dotto GP (2005) Negative control of keratinocyte differentiation by Rho/CRIK signaling coupled with up-regulation of KyoT1/2 (FHL1) expression. Proc Natl Acad Sci USA 102:11313–11318
Gruneberg U, Neef R, Li X, Chan EH, Chalamalasetty RB, Nigg EA, Barr FA (2006) KIF14 and citron kinase act together to promote efficient cytokinesis. J Cell Biol 172:363–372
Herculano-Houzel S (2009) The human brain in numbers: a linearly scaled-up primate brain. Front Hum Neurosci 3:31
Madaule P, Furuyashiki T, Reid T, Ishizaki T, Watanabe G, Morii N, Narumiya S (1995) A novel partner for the GTP-bound forms of rho and rac. FEBS Lett 377:243–248
Madaule P, Eda M, Watanabe N, Fujisawa K, Matsuoka T, Bito H, Ishizaki T, Narumiya S (1998) Role of citron kinase as a target of the small GTPase Rho in cytokinesis. Nature 394:491–494
Madaule P, Furuyashiki T, Eda M, Bito H, Ishizaki T, Narumiya S (2000) Citron, a Rho target that affects contractility during cytokinesis. Microsc Res Tech 49:123–126
Manzini MC, Walsh CA (2011) What disorders of cortical development tell us about the cortex: one plus one does not always make two. Curr Opin Genet Dev 21:333–339
Matsumura F (2005) Regulation of myosin II during cytokinesis in higher eukaryotes. Trends Cell Biol 15:371–377
Naim V, Imarisio S, Di Cunto F, Gatti M, Bonaccorsi S (2004) Drosophila citron kinase is required for the final steps of cytokinesis. Mol Biol Cell 15:5053–5063
Noctor SC, Martínez-Cerdeño V, Ivic L, Kriegstein AR (2004) Cortical neurons arise in symmetric and asymmetric division zones and migrate through specific phases. Nat Neurosci 7:136–144
Paramasivam M, Chang Y, LoTurco JJ (2007) ASPM and citron kinase co-localize to the midbody ring during cytokinesis. Cell Cycle 6:1605–1612
Rakic P (1988) Specification of cerebral cortical areas. Science 241:170–176
Roberts MR, Bittman K, Li W-W, French R, Mitchell B, LoTurco JJ, D’Mello SR (2000) The flathead mutation causes CNS-specific developmental abnormalities and apoptosis. J Neurosci 20:2295–2306
Rosenblatt J, Cramer LP, Baum B, McGee KM (2004) Myosin II-dependent cortical movement is required for centrosome separation and positioning during mitotic spindle assembly. Cell 117:361–372
Sarkisian MR, Frenkel M, Li W, Oborski JA, LoTurco JJ (2001) Altered interneuron development in the cerebral cortex of the flathead mutant. Cereb Cortex 11:734–743
Sarkisian MR, Li W, Di Cunto F, D’mello SR, LoTurco JJ (2002) Citron-kinase, a protein essential to cytokinesis in neuronal progenitors, is deleted in the flathead mutant rat. J Neurosci 22(8):RC217
Semendeferi K, Lu A, Schenker N, Damásio H (2002) Humans and great apes share a large frontal cortex. Nat Neurosci 5:272–276
Shaheen R, Al Tala S, Almoisheer A, Alkuraya FS (2014a) Mutation in PLK4, encoding a master regulator of centriole formation, defines a novel locus for primordial dwarfism. J Med Genet 51:814–816
Shaheen R, Faqeih E, Ansari S, Abdel-Salam G, Al-Hassnan ZN, Al-Shidi T, Alomar R, Sogaty S, Alkuraya FS (2014b) Genomic analysis of primordial dwarfism reveals novel disease genes. Genome Res 24:291–299
Shaheen R, Abdel-Salam GM, Guy MP, Alomar R, Abdel-Hamid MS, Afifi HH, Ismail SI, Emam BA, Phizicky EM, Alkuraya FS (2015) Mutation in WDR4 impairs tRNA m 7 G 46 methylation and causes a distinct form of microcephalic primordial dwarfism. Genome Biol 16:1
Shamseldin H, Alazami AM, Manning M, Hashem A, Caluseiu O, Tabarki B, Esplin E, Schelley S, Innes AM, Parboosingh JS (2015) RTTN mutations cause primary microcephaly and primordial Dwarfism in humans. Am J Hum Genet 97:862–868
Shandala T, Gregory SL, Dalton HE, Smallhorn M, Saint R (2004) Citron kinase is an essential effector of the Pbl-activated Rho signalling pathway in Drosophila melanogaster. Development 131:5053–5063
Sir J-H, Barr AR, Nicholas AK, Carvalho OP, Khurshid M, Sossick A, Reichelt S, D’Santos C, Woods CG, Gergely F (2011) A primary microcephaly protein complex forms a ring around parental centrioles. Nat Genet 43:1147–1153
Somma MP, Fasulo B, Cenci G, Cundari E, Gatti M (2002) Molecular dissection of cytokinesis by RNA interference in Drosophila cultured cells. Mol Biol Cell 13:2448–2460
Sweeney SJ, Campbell P, Bosco G (2008) Drosophila sticky/citron kinase is a regulator of cell-cycle progression, genetically interacts with Argonaute 1 and modulates epigenetic gene silencing. Genetics 178:1311–1325
Thornton GK, Woods CG (2009) Primary microcephaly: do all roads lead to Rome? Trends Genet 25:501–510
Woods CG, Bond J, Enard W (2005) Autosomal recessive primary microcephaly (MCPH): a review of clinical, molecular, and evolutionary findings. Am J Hum Genet 76:717–728
Yamashiro S, Totsukawa G, Yamakita Y, Sasaki Y, Madaule P, Ishizaki T, Narumiya S, Matsumura F (2003) Citron kinase, a Rho-dependent kinase, induces di-phosphorylation of regulatory light chain of myosin II. Mol Biol Cell 14:1745–1756
Zhang W, Vazquez L, Apperson M, Kennedy MB (1999) Citron binds to PSD-95 at glutamatergic synapses on inhibitory neurons in the hippocampus. J Neurosci 19:96–108
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We thank the study families for their enthusiastic participation. This work was supported by KACST grant 13-BIO1113-20 (FSA).
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Shaheen, R., Hashem, A., Abdel-Salam, G.M.H. et al. Mutations in CIT, encoding citron rho-interacting serine/threonine kinase, cause severe primary microcephaly in humans. Hum Genet 135, 1191–1197 (2016). https://doi.org/10.1007/s00439-016-1722-2
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DOI: https://doi.org/10.1007/s00439-016-1722-2