CFTR mutation enhances Dishevelled degradation and results in impairment of Wnt-dependent hematopoiesis

Abstract

Mutations of cystic fibrosis transmembrane conductance regulator (CFTR) cause cystic fibrosis (CF) with a multitude of clinical manifestations. Some CF patients develop clinically significant anemia, suggesting that CFTR may regulate hematopoiesis. Here, we report that cftr mutant zebrafish model exhibits primitive and definitive hematopoietic defects with impaired Wnt signaling. Cftr is found to interact, via its PDZ-binding domain (PDZBD), with Dishevelled (Dvl), a key component of Wnt signaling required for hematopoietic progenitor specification, thus protecting Dvl from Dapper1 (Dpr1)-induced lysosomal degradation. Defective hematopoiesis and impaired Wnt signaling in cftr mutant can be rescued by overexpression of wild-type or channel function-defective G551D mutant CFTR with an intact PDZBD, but not Cftr with mutations in the PDZBD. Analysis of human database (http://r2.amc.nl) shows that CFTR is positively correlated with DVL2 and Wnt-related hematopoietic factors in human blood system. The results reveal a previously unrecognized role of CFTR, which is independent of its channel function, in regulating DVL degradation and thus Wnt signaling required for hematopoiesis in both zebrafish and humans, providing an explanation for the anemic phenotype of CF patients.

CFTR is required for the migration of primordial germ cells during zebrafish early embryogenesis

“…Similar to the expression profile in mouse embryos, cftr was ubiquitously expressed in zebrafish embryos ( Sun et al 2018 ). To investigate the potential involvement of Cftr in PGCs development, we inserted mutations near the start codon of Cftr using CRISPR/Cas9 system ( Fig.…”

“…According to Navis et al 's description ( Navis et al 2013 ) and our previous study, CFTR is expressed ubiquitously during early embryogenesis ( Sun et al 2018 ), suggesting that CFTR may regulate PGCs migration by effect on both neighboring somatic cells and PGCs themselves. Our results show that genes both expressed specifically in PGCs, including rgs14a and ca15b, and somatic cells, including cxcr4b and cxcl12a, detected in this work are significantly elevated in offspring embryos from mutant line, suggesting that CFTR sustains PGCs migration through regulating key factors distributed at embryo widely.…”

“…We also found that a large percentage of homozygous cftr -mutant larvae was lost beginning around 10 dpf ( Navis & Bagnat 2015 ). Similar to our previous work ( Sun et al 2018 ), we used heterozygous cftr mutant line instead in this study, and the offspring of the heterozygous crosses (mutant line) could be WT (25%), heterozygous cftr +/− (50%) and homozygous cftr −/− mutants (25%).

Figure 1 Targeted indel mutation induced by engineered Cas9/gRNA at the cftr gene in zebrafish.

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“…Nevertheless, a large percentage of homozygous cftr -mutant larvae was lost beginning around 10 dpf ( Navis & Bagnat 2015 ); furthermore, fertility rate of adult homozygous cftr −/− fish was very low, which brought difficulty to experiment. Therefore, we used heterozygous cftr mutant line instead in this study, similar to our previous work ( Sun et al 2018 ).…”

DVL1 and DVL3 differentially localize to CYP19A1 promoters and regulate aromatase mRNA in breast cancer cells

“…While studies report that DVL function is altered in diverse pathophysiological settings, its mechanistic role remains unclear in many of these conditions [ 1 – 3 ]. WNT signaling is critical for organismal development and DVL integrates an immense number of upstream signals that may arise from as many as 19 different WNTs, 10 Frizzled receptors and multiple co-receptors and secreted antagonists.…”