Mutations in CCDC11 , which Encodes a Coiled-Coil Containing Ciliary Protein, Causes Situs Inversus Due to Dysmotility of Monocilia in the Left-Right Organizer

Abstract

In vertebrates, establishment of left-right (LR) asymmetry is dependent on cilia-driven fluid flow within the LR organizer. Mutations in CCDC11 disrupt LR asymmetry in humans, but how the gene functions in LR patterning is presently unknown. We describe a patient with situs inversus totalis carrying homozygous loss-of-function mutations in CCDC11. We show that CCDC11 is an axonemal protein in respiratory cilia, but is largely dispensable for their structure and motility. To investigate the role of CCDC11 in LR development, we studied the zebrafish homolog of the gene. Like in human respiratory cilia, loss of Ccdc11 causes minor defects in the motility of zebrafish kidney cilia, although the protein localizes to their axonemes and base. By contrast, Ccdc11 localizes exclusively to the basal bodies of cilia within Kupffer's vesicle, the organ of laterality of teleost fishes, and within the spinal canal. Moreover, the rotational motion of the cilia in these tissues of ccdc11-deficient embryos was strongly impaired. Our findings demonstrate that CCDC11 has a conserved essential function in cilia of the vertebrate LR organizer. To the best of our knowledge, this is the first ciliary component, which has a differential localization and function in different kinds of motile cilia.

The Heterotaxy Gene CCDC11 is Essential for Cytokinesis and Cell-Cell Adhesion via RhoA Regulation

“…depletion strategy, F0 CRISPR or MO, ccdc11 depletion is critical for global LR patterning consistent with previous studies [12][13][14].…”

“…CCDC11 plays a key role in establishing LR asymmetry [12][13][14][15]. A number of Htx patients have mutations in CCDC11, and depletion of ccdc11 causes LR patterning defects in zebrafish and Xenopus [12][13][14][15]. However, analysis in Xenopus was restricted to examination of coco and pitx2 [12].…”

“…CCDC11, which is also known as cilia and flagella associated protein 53 (CFAP53), is known to localize to the ciliary base [13,14]. However, given CCDC11's newly-identified role in cytokinesis and cell-cell adhesion, we decided to re-examine its localization.…”

“…Repression of dand5 leads to expression of pitx2 in the left lateral plate mesoderm [1,9,10]. Pitx2 drives asymmetric organogenesis such that the heart, which initiates as a midline tube, loops to the right while other organs like the gut also undergo asymmetric morphogenesis [11].Therefore, a signaling cascade including cilia-driven extracellular fluid flow, dand5, and pitx2 establish laterality of internal organs such as the heart.CCDC11 plays a key role in establishing LR asymmetry [12][13][14][15]. A number of Htx patients have mutations in CCDC11, and depletion of ccdc11 causes LR patterning defects in zebrafish and Xenopus [12][13][14][15].…”

Antagonistic interactions in the zebrafish midline prior to the emergence of asymmetric gene expression are important for left–right patterning

“…In vertebrates, a major model for how L-R asymmetries are initiated involves an asymmetric fluid flow within LRCs, driven by the rotation of polarized motile cilia [19,20,23,[45][46][47][48][49][50][51][52][53]. In support of this model, a plethora of mutants that exhibit cilia motility abnormalities also display defects of L-R patterning (for just a few examples see [54][55][56][57][58] Once asymmetric gene expression is established in the LPM, midline structures are also critical for maintaining asymmetries. Initial analysis of zebrafish mutants, in which an intact notochord fails to form, revealed defects in asymmetric gene expression in the LPM with subsequent abnormalities in cardiac asymmetry [76][77][78].…”