CEP290 tethers flagellar transition zone microtubules to the membrane and regulates flagellar protein content

Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
The Journal of Cell Biology (Impact Factor: 9.83). 09/2010; 190(5):927-40. DOI: 10.1083/jcb.201006105
Source: PubMed


Mutations in human CEP290 cause cilia-related disorders that range in severity from isolated blindness to perinatal lethality. Here, we describe a Chlamydomonas reinhardtii mutant in which most of the CEP290 gene is deleted. Immunoelectron microscopy indicated that CEP290 is located in the flagellar transition zone in close association with the prominent microtubule-membrane links there. Ultrastructural analysis revealed defects in these microtubule-membrane connectors, resulting in loss of attachment of the flagellar membrane to the transition zone microtubules. Biochemical analysis of isolated flagella revealed that the mutant flagella have abnormal protein content, including abnormal levels of intraflagellar transport proteins and proteins associated with ciliopathies. Experiments with dikaryons showed that CEP290 at the transition zone is dynamic and undergoes rapid turnover. The results indicate that CEP290 is required to form microtubule-membrane linkers that tether the flagellar membrane to the transition zone microtubules, and is essential for controlling flagellar protein composition.

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    • ", whereas no POC genes are in this subset ( Supplemental Data Set 7 ) . Although the specific functions of most POC genes are unknown , the POC3 / CEP290 gene product localizes mainly to the transition zone and is required for flagella assembly , and therefore does not match our prediction for in - volvement in basal body assembly or replication ( Craige et al . , 2010 ) . Three additional large data sets of candidate flagella / basal body protein coding genes were investigated based on their synchronous expression profiles : genes encoding proteins of the flagella pro - teome ( FAPs ) ( Pazour et al . , 2005 ) , CiliaCut genes that are con - served in ciliated species but missing from species without"
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    • "In some experiments, palmelloid cells were induced to grow flagella by treatment with autolysin prepared by the method of Craige et al. (2010). "
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    • "In support of a conserved role for the TZ, orthologues of the genes encoding components of the MKS and NPHP complexes are present in other ciliated organisms, including Caenorhabditis elegans and Chamydomonas reinhardtii (Craige et al., 2010; Williams et al., 2011; Reiter et al., 2012). Inherited defects in ciliary function underlie a diverse set of diseases called ciliopathies. "
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    ABSTRACT: The Meckel syndrome (MKS) complex functions at the transition zone, located between the basal body and axoneme, to regulate the localization of ciliary membrane proteins. We investigated the role of Tmem231, a two-pass transmembrane protein, in MKS complex formation and function. Consistent with a role in transition zone function, mutation of mouse Tmem231 disrupts the localization of proteins including Arl13b and Inpp5e to cilia, resulting in phenotypes characteristic of MKS such as polydactyly and kidney cysts. Tmem231 and B9d1 are essential for each other and other complex components such as Mks1 to localize to the transition zone. As in mouse, the Caenorhabditis elegans orthologue of Tmem231 localizes to and controls transition zone formation and function, suggesting an evolutionarily conserved role for Tmem231. We identified TMEM231 mutations in orofaciodigital syndrome type 3 (OFD3) and MKS patients that compromise transition zone function. Thus, Tmem231 is critical for organizing the MKS complex and controlling ciliary composition, defects in which cause OFD3 and MKS. © 2015 Roberson et al.
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