CFAP43 modulates ciliary beating in mouse and Xenopus

Abstract

Malfunctions of motile cilia cause a variety of developmental defects and diseases in humans and animal model organisms. Defects include impaired mucociliary clearance of the airways, sperm immotility, hydrocephalus and organ laterality. Here, we characterize the evolutionary conserved Cfap43 gene by loss-of-function experiments in the mouse and the frog Xenopus laevis. Cfap43 is expressed in tissues carrying motile cilia and acts as a target gene of the transcription factor FOXJ1, which is essential for the induction of motile ciliogenesis. We show that CFAP43, a protein of unknown biochemical function, localizes to the ciliary axoneme. CFAP43 is involved in the regulation of the beating frequency of tracheal cilia and loss of CFAP43 causes severe mucus accumulation in the nasal cavity. Likewise, morphant and crispant frog embryos revealed impaired function of motile cilia of the larval epidermis, a model for airway mucociliary epithelia. CFAP43 participates in the formation of flagellar axonemes during spermatogenesis as mice mutant for Cfap43 display male infertility, consistent with observations in male sterile patients. In addition, mice mutant for Cfap43 display early onset hydrocephalus. Together, these results confirm the role of CFAP43 in the male reproductive tract and pinpoint additional functions in airway epithelia mucus clearance and brain development.

The FOXJ1 target Cfap206 is required for sperm motility, mucociliary clearance of the airways and brain development

“…6F). This differs from Tll1 (Ikegami et al, 2010) and Cfap43 mutants (Rachev et al, 2020), in which an increase in beating frequency was associated with reduced cilia-generated flow. Although loss of CFAP206 clearly affects ciliary beating in respiratory epithelium, it remains to be seen how this relates to mucous accumulation.…”

“…To address potential changes in ciliary beating of cfap206 crispants, motility of epidermal MCCs was analysed in high-speed time-lapse videos recorded from wild-type and crispant larvae at stage 32 (Movie 1). Ciliary beat frequencies were calculated as previously reported (Rachev et al, 2020) and found to be significantly elevated, from 22.5 Hz in wild type to 24.5 Hz in sgRNA1 crispants and 26.5 Hz in sgRNA2 crispants ( Fig. 4Aa; Table S3).…”

“…4Ab). In order to investigate whether the function of epidermal MCCs was altered in crispants, fluorescent beads were added to stage 32 larvae and bead transport was assessed in time-lapse movies (Movie 2) as described previously (Rachev et al, 2020). In comparison with wild-type specimens, bead transport was significantly reduced, from 550 µm/s in wild type to 460 µm/s in sgRNA1 crispants and 410 µm/s in sgRNA2 crispants ( Fig.…”

“…2B). The dependence of cfap206 transcription on foxj1 was analysed in specimens that were genome edited at the foxj1 gene locus by CRIPSR/Cas9 (Rachev et al, 2020). Signal intensities were greatly reduced in crispants ( Fig.…”

“…Embedded tissues were sectioned at 5 or 10 μm. Sperm cells were isolated as described previously (Rachev et al, 2020).…”