Alternative titles; symbols
HGNC Approved Gene Symbol: CPAP
Cytogenetic location: 13q12.12-q12.13 Genomic coordinates (GRCh38) : 13:24,882,279-24,934,000 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 13q12.12-q12.13 | ?Seckel syndrome 4 | 613676 | Autosomal recessive | 3 |
| Microcephaly 6, primary, autosomal recessive | 608393 | Autosomal recessive | 3 |
The CENPJ gene encodes a centrosomal protein with a putative role in regulation of microtubule assembly and nucleation (Hung et al., 2000).
Using the head domain of 4.1R (EPB41; 130500) as bait in a yeast 2-hybrid screen of a lymphocyte cDNA library, followed by screening a testis cDNA library, Hung et al. (2000) cloned CENPJ, which they designated CPAP. The deduced 1,338-amino acid protein has a calculated molecular mass of 153 kD. CPAP contains 5 coiled-coil domains, the most C-terminal of which includes a leucine zipper motif. It also has several potential protein phosphorylation sites and a C-terminal domain containing 21 nonamer G-box repeats. The leucine zipper and G-box motifs share significant similarity with TCP10 (187020). Northern blot analysis detected a major 4.5-kb transcript in all tissues and cell lines examined, with highest expression in testis. Western blot analysis of 2 human cell lines and mouse testis detected CPAP at an apparent molecular mass of 153 kD.
Bond et al. (2005) stated that the CENPJ gene contains 17 exons.
Darvish et al. (2010) noted that the CENPJ gene maps to chromosome 13q12.2.
Hung et al. (2000) determined that epitope-tagged CPAP interacted with endogenous EPB41 in a cervical carcinoma cell line. By testing the interaction of recombinant truncated proteins, they determined that the C terminus of CPAP interacted with a region of EPB41 between amino acids 127 and 198. Immunoprecipitation analysis of a leukemia cell line indicated that CPAP interacted with endogenous EPB41 in a gamma-tubulin (see 191135) complex. CPAP colocalized with gamma-tubulin in both the centrosomal and cytosolic fractions, and both proteins followed the dynamic movement of centrosomes during the cell cycle. Coincubation of microtubules with anti-CPAP or anti-gamma-tubulin antibodies altered both the number and length of the microtubules. The association of CPAP with the centrosome was independent of microtubules. Hung et al. (2000) concluded that CPAP is a centrosomal protein that may have a role in microtubule nucleation.
Using recombinant truncated CPAP peptides in an in vitro microtubule nucleation assay, Hung et al. (2004) identified a 112-amino acid domain (residues 311 to 422) able to destabilize microtubules. This domain could both inhibit microtubule nucleation from the centrosome and depolymerize taxol-stabilized microtubules. The destabilizing domain recognized the plus ends of microtubules and was able to bind tubulin dimers. Regulated overexpression of this domain in HeLa cells inhibited cell proliferation and induced apoptosis after G2/M arrest.
By yeast 2-hybrid analysis, in vitro pull-down assays, and coimmunoprecipitation of human embryonic kidney cell lysates, Koyanagi et al. (2005) found a direct interaction between CPAP and RELA (164014). Overexpression of CPAP enhanced nuclear factor kappa-B (NFKB)-dependent transcription induced by TNF-alpha (191160), and reduction of CPAP protein levels by RNA interference resulted in decreased activation of NFKB by TNF-alpha. Although CPAP was found primarily in the cytoplasm of unstimulated mammary carcinoma cells, TNF-alpha treatment led to nuclear accumulation of a portion of CPAP. CPAP also immunoprecipitated with RELA in a complex with DNA containing an NFKB-binding motif, and when tethered to a transcriptional promoter, CPAP could activate gene expression. Koyanagi et al. (2005) also observed an interaction between CPAP and the coactivator EP300 (602700)/CREBBP (600140), leading to synergistic activation of NFKB transcriptional activity. They concluded that CPAP-dependent transcriptional activation is likely to include EP300/CREBBP.
Using immunoprecipitation analysis, Chen et al. (2006) showed that CPAP interacted with 14-3-3 proteins (e.g., YWHAG; 605356). The authors identified 2 highly conserved classical 14-3-3-binding motifs in CPAP, and mutation analysis revealed that the second motif mediated interaction with 14-3-3 proteins. Mutation analysis showed that ser1109 in the second 14-3-3-binding motif of CPAP played a major role in interaction with 14-3-3 proteins, and phosphorylation of ser1109 appeared to be essential for the interaction. Interaction of CPAP with 14-3-3 proteins was not involved in targeting CPAP to the centrosome, as mutation of ser1109 did not affect localization of CPAP to interphase centrosome or to mitotic spindle poles. Further analysis indicated that association of CPAP and 14-3-3 was regulated during cell cycle progression, as CPAP-14-3-3 interaction was significantly reduced in mitotic cells.
Through siRNA-mediated depletion and immunoelectron microscopy directed to individual centrosomal proteins, Kleylein-Sohn et al. (2007) found that CENPJ, PLK4 (605031), SAS6 (SASS6; 609321), CEP135 (611423), TUBG1 (191135), and CP110 (609544) were required at different stages of procentriole formation and were associated with different centriolar structures. SAS6 associated only transiently with nascent procentrioles, whereas CEP135 and CENPJ formed a core structure within the proximal lumen of both parental and nascent centrioles. Finally, CP110 was recruited early and then associated with the growing distal tips, indicating that centrioles elongate through insertion of alpha-tubulin (see 191110)/beta-tubulin (191130) underneath a CP110 cap.
Using synchronized HeLa cells, Tang et al. (2009) found that the level of CPAP increased gradually from early S phase until mitosis. As cells exited mitosis and entered early G1 phase, both SAS6 and CPAP levels decreased significantly. Inhibitor and mutation experiments revealed that CPAP was targeted for proteasome-mediated degradation by the anaphase-promoting complex/cyclosome (APC/C; see 608473)-CDH1 (192090) system and that the first KEN box and fourth D box of CPAP were required for its degradation. Depletion of CPAP via siRNA suppressed centriole amplification during the cell cycle. Conversely, overexpression of CPAP in mouse or human cells resulted in the formation of elongated procentriole-like microtubule-based structures, which required the tubulin-binding activity of CPAP. Depletion of SAS6 affected these CPAP-induced structures when they were growing from newly formed procentrioles, but not from preexisting parental centrioles. Tang et al. (2009) proposed that CPAP regulates centriole length via its tubulin-binding activity and that it is recruited to procentrioles following activation of PLK4 on the proximal end of the parental centriole and recruitment of SAS6 to the base of nascent procentrioles. They suggested that this model of CPAP function requires strict control of CPAP expression and inhibition of its microtubule-destabilizing activity in S/G2 phase.
Using immunoprecipitation analysis and protein pull-down assays, Lin et al. (2013) found that CEP120 (613446) interacted with CPAP in human cell lines. Overexpression of either protein caused formation of supernumerary centrioles and extra long and abnormally branched microtubule-based filaments that extended from elongated centrioles. Depletion of CEP120 or CPAP in U2OS cells reduced centriolar targeting of the other protein.
Comartin et al. (2013) found that CEP120 interacted with both SPICE1 (613447) and CPAP, and that all 3 proteins were required for centriole elongation and for recruitment of distal microtubule-capping proteins and CEP135 to procentrioles.
Firat-Karalar et al. (2014) found that overexpression of CPAP in U2OS cells caused centriole elongation. Proximity interaction assays revealed that CPAP interacted with several centriolar proteins, including CEP152 (613529), which functions as a scaffold for procentriole formation.
Using mass spectrometric analysis, Gudi et al. (2014) identified CEP152 as a centrobin (CNTROB; 611425)-interacting protein, with the N-terminal region of centrobin binding to CEP152. Centrobin functioned downstream of CEP152 during centriole biogenesis, and its procentriole localization was dependent on CEP152. Knockdown analysis in HeLa cells revealed that centrobin and CPAP were recruited to procentrioles after CEP152. Centrobin directly interacted with CPAP, and the interaction was mediated by a CPAP-binding domain (CBD) within the N-terminal region of centrobin. Exogenous expression of the centrobin CBD resulted in loss of CPAP from preexisting centrioles and procentrioles and led to inhibition of centriole duplication in HeLa cells, suggesting that the centrobin-CPAP interaction controls the maintenance of CPAP levels on centrioles and is critical for centriole biogenesis. The centrobin CBD inhibited PLK4 overexpression-associated centriole amplification, indicating that the centrobin CBD blocked centriole duplication at the initiation stages by interfering with endogenous centrobin-CPAP interaction. In support, depletion of centrobin inhibited PLK4-mediated de novo initiation of centriole duplication. Centriolar recruitment of CPAP only happened after centrobin localized to procentrioles, and interaction with centrobin was essential for CPAP localization on centrioles. In agreement, centrobin-depleted U2OS cells did not show CPAP recruitment to centrioles and centriole elongation, but reintroduction of centrobin restored these features.
Primary Microcephaly 6
In 3 families in which primary microcephaly mapped to 13q12.2 (MCPH6; 608393), of which 1 was previously described by Leal et al. (2003) and 2 were Pakistani, Bond et al. (2005) used a positional cloning strategy to identify candidate genes in the region. Genotyping polymorphic microsatellite markers narrowed the region to 3.1 Mb. Bioinformatic analysis of the region identified CENPJ as a likely candidate. A homozygous mutation in the CENPJ gene was identified in each of the 3 MCPH6 families (609279.0001-609279.0002, respectively). Each mutation was absent from 380 northern Pakistani control chromosomes, showed the expected disease segregation in families, and was not present in chimpanzee, gorilla, orangutan, gibbon, mouse, or rat.
In affected members of a consanguineous Pakistani family with microcephaly linked to the MCPH6 locus on chromosome 13q12.12-q12.13, Gul et al. (2006) identified homozygosity for a deletion in the CENPJ gene (609279.0003).
Darvish et al. (2010) identified a homozygous mutation in the CENPJ gene (609279.0005) in a consanguineous Iranian families with MCPH6. The patients had additional features, including mild facial dysmorphism and seizures.
In affected members of 3 consanguineous Pakistani families with MCPH6, Sajid Hussain et al. (2013) identified a homozygous frameshift mutation in the CENPJ gene (609279.0001). The mutation, which was found by linkage analysis followed by Sanger sequencing of the candidate gene, segregated with the disorder in the families. The families were ascertained from a larger cohort of 57 consanguineous Pakistani families with autosomal recessive microcephaly who underwent linkage analysis to known MCPH loci.
Seckel Syndrome 4
In an extended consanguineous family with clinical features of Seckel syndrome (SCKL4; 613676), Al-Dosari et al. (2010) identified a homozygous splicing mutation in the last nucleotide of intron 11 of the CENPJ gene (IVS11-1G-C; 609279.0004) resulting in the segregation of 3 different transcripts of CENPJ.
Using a gene-trap protocol, McIntyre et al. (2012) created homozygous Cenpj hypomorphic (Cenpj tm/tm) mice, which showed residual expression of full-length Cenpj and phenocopied many features of Seckel syndrome. Cenpj tm/tm mice were obtained at less than the expected mendelian ratio and were smaller than wildtype due to intrauterine and postnatal growth retardation. Cenpj tm/tm mice had a flatter, sloping forehead compared with wildtype, and they had other skeletal abnormalities, including mild elevation of parietal bone, irregular ribcage, bowed humeri, widened iliac crests, and short lumbar and sacral vertebrae. Adult Cenpj tm/tm brain appeared largely normal, but it had reduced neuron numbers due to apoptosis, with significant reduction particularly in the striatum. Social recognition tests revealed impaired long-term memory in Cenpj tm/tm mice, although short-term memory and other neurologic and behavioral functions appeared normal. Other abnormalities in Cenpj tm/tm mice included delayed female puberty, structural and developmental abnormalities of eye, delayed response to glucose challenge, disorganized cardiomyocytes with increased incidence of karyomegaly and multinucleated cells, and increased total T cells due to increased Cd3 (see 186940)- and Cd8 (see 186910)-positive T cells. Cultured embryonic Cenpj tm/tm fibroblasts showed genomic instability concomitant with abnormal number of centrioles, extensive polyploidy and aneuploidy, increased frequency of both monopolar and multipolar spindles, and lagging chromosomes at anaphase. McIntyre et al. (2012) concluded that dwarfism in Cenpj tm/tm mice was due to widespread DNA damage and apoptosis in embryos rather than reduced cell proliferation.
Ding et al. (2019) found that mice with conditional knockout of Cenpj in neural progenitor cells (NPCs) had abnormal cilia and microcephaly, consistent with the phenotypes of microcephaly patients with CENPJ mutations. Cilia of mutant mice were longer, disarrayed with smaller diameters, and curled and tangled with bulges and curly tips. Cenpj regulated cilia disassembly, and consequently abnormal cilia disassembly influenced radial glial cell proliferation during development in mutant embryos. Furthermore, abnormal cilia caused by Cenpj depletion reduced NPC proliferation capacity and progenitor number, resulting in cortical thickness reduction during brain development. Adult mutant mice also showed a strong microcephalic phenotype, as Cenpj deletion reduced adult neural stem cells, resulting in long and thin primary cilia and motile cilia in adult neural stem cells and reduced cell proliferation in subventricular zone. Mechanistically, Cenpj regulated cilia disassembly and cortical development through Kif2a (602591). Kif2a appeared to be a downstream effector for Cenpj in regulating cilium disassembly and was responsible for NPC generation and cortical development.
In affected members of 2 families with primary microcephaly-6 (MCPH6; 608393), one from Brazil and previously described by Leal et al. (2003) and the other from Pakistan, Bond et al. (2005) identified a homozygous 1-bp deletion in the CENPJ gene, 17delC, resulting in a frameshift and a premature stop codon (Thr6fsTer3).
In 10 patients from 3 Pakistani families with MCPH6, Sajid Hussain et al. (2013) identified a homozygous 1-bp deletion (c.18delC) in exon 2 of the CENPJ gene, resulting in a frameshift and premature termination (Ser7ProfsTer2). The mutations, which were found by linkage analysis followed by Sanger sequencing of the candidate gene, segregated with the disorder in the families. Sajid Hussain et al. (2013) stated that this was the same mutation reported by Bond et al. (2005) as 17delC, and postulated a founder effect.
In affected members of a Pakistani family with primary microcephaly-6 (MCPH6; 608393), Bond et al. (2005) identified homozygosity for a 3704A-T transversion in exon 16 of the CENPJ gene, resulting in a glu1235-to-val (E1235V) substitution.
In affected members of a consanguineous Pakistani family with primary microcephaly-6 (MCPH6; 608393), Gul et al. (2006) identified homozygosity for a 4-bp deletion (3243delTCAG) in exon 11 of the CENPJ gene, resulting in a frameshift and a premature stop codon 19 basepairs downstream. The mutation was not found in 100 unrelated, ethnically matched control chromosomes.
In affected members of a consanguineous Saudi family with Seckel syndrome-4 (SCKL4; 613676), Al-Dosari et al. (2010) identified a homozygous splicing mutation in the last nucleotide of intron 11 of the CENPJ gene (IVS11-1G-C), which fully segregated with the phenotype in the family and was not found in 96 Saudi controls. Reverse transcription revealed that this splice junction mutation completely abolishes the consensus splice acceptor site and decreases the efficiency of the 2 adjacent acceptor sites, leading to segregation of 3 different transcripts.
In 2 sibs, born of consanguineous Iranian parents, with primary microcephaly-6 (MCPH6; 608393), Darvish et al. (2010) identified a homozygous 2462C-T transition in exon 7 of the CENPJ gene, resulting in a thr821-to-met (T821M) substitution, which may disrupt the TCP10 domain and interfere with normal protein function. The mutation was not found in 160 German and 190 Iranian controls. The patients had some additional features, including small ears, hypertelorism, notched nasal tip, seizures, joint stiffness, and wheelchair requirement.
Al-Dosari, M. S., Shaheen, R., Colak, D., Alkuraya, F. S. Novel CENPJ mutation causes Seckel syndrome. J. Med. Genet. 47: 411-414, 2010. [PubMed: 20522431] [Full Text: https://doi.org/10.1136/jmg.2009.076646]
Bond, J., Roberts, E., Springell, K., Lizarraga, S., Scott, S., Higgins, J., Hampshire, D. J., Morrison, E. E., Leal, G. F., Silva, E. O., Costa, S. M. R., Baralle, D., Raponi, M., Karbani, G., Rashid, Y., Jafri, H., Bennett, C., Corry, P., Walsh, C. A., Woods, C. G. A centrosomal mechanism involving CDK5RAP2 and CENPJ controls brain size. Nature Genet. 37: 353-355, 2005. Note: Erratum: Nature Genet. 37: 555 only, 2005. [PubMed: 15793586] [Full Text: https://doi.org/10.1038/ng1539]
Chen, C. Y., Olayioye, M. A., Lindeman, G. J., Tang, T. K. CPAP interacts with 14-3-3 in a cell cycle-dependent manner. Biochem. Biophys. Res. Commun. 342: 1203-1210, 2006. [PubMed: 16516142] [Full Text: https://doi.org/10.1016/j.bbrc.2006.02.089]
Comartin, D., Gupta, G. D., Fussner, E., Coyaud, E., Hasegan, M., Archinti, M., Cheung, S. W. T., Pinchev, D., Lawo, S., Raught, B., Bazett-Jones, D. P., Luders, J., Pelletier, L. CEP120 and SPICE1 cooperate with CPAP in centriole elongation. Curr. Biol. 23: 1360-1366, 2013. [PubMed: 23810536] [Full Text: https://doi.org/10.1016/j.cub.2013.06.002]
Darvish, H., Esmaeeli-Nieh, S., Monajemi, G. B., Mohseni, M., Ghasemi-Firouzabadi, S., Abedini, S. S., Bahman, I., Jamali, P., Azimi, S., Mojahedi, F., Dehghan, A., Shafeghati, Y., and 14 others. A clinical and molecular genetic study of 112 Iranian families with primary microcephaly. J. Med. Genet. 47: 823-828, 2010. Note: Erratum: J. Med. Genet. 51: 70 only, 2014. [PubMed: 20978018] [Full Text: https://doi.org/10.1136/jmg.2009.076398]
Ding, W., Wu, Q., Sun, L., Pan, N. C., Wang, X. Cenpj regulates cilia disassembly and neurogenesis in the developing mouse cortex. J. Neurosci. 39: 1994-2010, 2019. [PubMed: 30626697] [Full Text: https://doi.org/10.1523/JNEUROSCI.1849-18.2018]
Firat-Karalar, E., Rauniyar, N., Yates, J. R., III, Stearns, T. Proximity interactions among centrosome components identify regulators of centriole duplication. Curr. Biol. 24: 664-670, 2014. [PubMed: 24613305] [Full Text: https://doi.org/10.1016/j.cub.2014.01.067]
Gudi, R., Zou, C., Dhar, J., Gao, Q., Vasu, C. Centrobin-centrosomal protein 4.1-associated protein (CPAP) interaction promotes CPAP localization to the centrioles during centriole duplication. J. Biol. Chem. 289: 15166-15178, 2014. [PubMed: 24700465] [Full Text: https://doi.org/10.1074/jbc.M113.531152]
Gul, A., Hassan, M. J., Hussain, S., Raza, S. I., Chishti, M. S., Ahmad, W. A novel deletion mutation in CENPJ gene in a Pakistani family with autosomal recessive primary microcephaly. J. Hum. Genet. 51: 760-764, 2006. [PubMed: 16900296] [Full Text: https://doi.org/10.1007/s10038-006-0017-1]
Hung, L.-Y., Chen, H.-L., Chang, C.-W., Li, B.-R., Tang, T. K. Identification of a novel microtubule-destabilizing motif in CPAP that binds to tubulin heterodimers and inhibits microtubule assembly. Molec. Biol. Cell 15: 2697-2706, 2004. [PubMed: 15047868] [Full Text: https://doi.org/10.1091/mbc.e04-02-0121]
Hung, L.-Y., Tang, C.-J. C., Tang, T. K. Protein 4.1 R-135 interacts with a novel centrosomal protein (CPAP) which is associated with the gamma-tubulin complex. Molec. Cell. Biol. 20: 7813-7825, 2000. [PubMed: 11003675] [Full Text: https://doi.org/10.1128/MCB.20.20.7813-7825.2000]
Kleylein-Sohn, J., Westendorf, J., Le Clech, M., Habedanck, R., Stierhof, Y.-D., Nigg, E. A. Plk4-induced centriole biogenesis in human cells. Dev. Cell 13: 190-202, 2007. [PubMed: 17681131] [Full Text: https://doi.org/10.1016/j.devcel.2007.07.002]
Koyanagi, M., Hijikata, M., Watashi, K., Masui, O., Shimotohno, K. Centrosomal P4.1-associated protein is a new member of transcriptional coactivators for nuclear factor-kappa-B. J. Biol. Chem. 280: 12430-12437, 2005. [PubMed: 15687488] [Full Text: https://doi.org/10.1074/jbc.M410420200]
Leal, G. F., Roberts, E., Silva, E. O., Costa, S. M. R., Hampshire, D. J., Woods, C. G. A novel locus for autosomal recessive primary microcephaly (MCPH6) maps to 13q12.2. J. Med. Genet. 40: 540-542, 2003. [PubMed: 12843329] [Full Text: https://doi.org/10.1136/jmg.40.7.540]
Lin, Y.-N., Wu, C.-T., Lin, Y.-C., Hsu, W.-B., Tang, C.-J. C., Chang, C.-W., Tang, T. K. CEP120 interacts with CPAP and positively regulates centriole elongation. J. Cell Biol. 202: 211-219, 2013. [PubMed: 23857771] [Full Text: https://doi.org/10.1083/jcb.201212060]
McIntyre, R. E., Lakshminarasimhan Chavali, P., Ismail, O., Carragher, D. M., Sanchez-Andrade, G., Forment, J. V., Fu, B., Del Castillo Velasco-Herrera, M., Edwards, A., van der Weyden, L., Yang, F., Sanger Mouse Genetics Project, and 12 others. Disruption of mouse Cenpj, a regulator of centriole biogenesis, phenocopies Seckel syndrome. PLoS Genet. 8: e1003022, 2012. Note: Electronic Article. [PubMed: 23166506] [Full Text: https://doi.org/10.1371/journal.pgen.1003022]
Sajid Hussain, M., Marriam Bakhtiar, S., Farooq, M., Anjum, I., Janzen, E., Reza Toliat, M., Eiberg, H., Kjaer, K. W., Tommerup, N., Noegel, A. A., Nurnberg, P., Baig, S. M., Hansen, L. Genetic heterogeneity in Pakistani microcephaly families. Clin. Genet. 83: 446-451, 2013. [PubMed: 22775483] [Full Text: https://doi.org/10.1111/j.1399-0004.2012.01932.x]
Tang, C.-J. C., Fu, R.-H., Wu, K.-S., Hsu, W.-B., Tang, T. K. CPAP is a cell-cycle regulated protein that controls centriole length. Nature Cell Biol. 11: 825-831, 2009. [PubMed: 19503075] [Full Text: https://doi.org/10.1038/ncb1889]