Aryl hydrocarbon receptor is required for optimal B-cell proliferation
EMBO JOURNAL
Authors: Villa, Matteo; Gialitakis, Manolis; Tolaini, Mauro; Ahlfors, Helena; Henderson, Colin J.; Wolf, C. Roland; Brink, Robert; Stockinger, Brigitta
Abstract
The aryl hydrocarbon receptor (AhR), a transcription factor known for mediating xenobiotic toxicity, is expressed in B cells, which are known targets for environmental pollutants. However, it is unclear what the physiological functions of AhR in B cells are. We show here that expression of Ahr in B cells is up-regulated upon B-cell receptor (BCR) engagement and IL-4 treatment. Addition of a natural ligand of AhR, FICZ, induces AhR translocation to the nucleus and transcription of the AhR target gene Cyp1a1, showing that the AhR pathway is functional in B cells. AhR-deficient (Ahr(-/-)) B cells proliferate less than AhR-sufficient (Ahr(+/+)) cells following invitro BCR stimulation and invivo adoptive transfer models confirmed that Ahr(-/-) B cells are outcompeted by Ahr(+/+) cells. Transcriptome comparison of AhR-deficient and AhR-sufficient B cells identified cyclin O (Ccno), a direct target of AhR, as a top candidate affected by AhR deficiency.
Unexpected genetic heterogeneity for primary ciliary dyskinesia in the Irish Traveller population
EUROPEAN JOURNAL OF HUMAN GENETICS
Authors: Casey, Jillian P.; McGettigan, Paul A.; Healy, Fiona; Hogg, Claire; Reynolds, Alison; Kennedy, Breandan N.; Ennis, Sean; Slattery, Dubhfeasa; Lynch, Sally A.
Abstract
We present a study of five children from three unrelated Irish Traveller families presenting with primary ciliary dyskinesia (PCD). As previously characterized disorders in the Irish Traveller population are caused by common homozygous mutations, we hypothesised that all three PCD families shared the same recessive mutation. However, exome sequencing showed that there was no pathogenic homozygous mutation common to all families. This finding was supported by histology, which showed that each family has a different type of ciliary defect; transposition defect (family A), nude epithelium (family B) and absence of inner and outer dynein arms (family C). Therefore, each family was analysed independently using homozygosity mapping and exome sequencing. The affected siblings in family A share a novel 1 bp duplication in RSPH4A (NM_001161664.1:c.166dup; p.Arg56Profs*11), a radial-spoke head protein involved in ciliary movement. In family B, we identified three candidate genes (CCNO, KCNN3 and CDKN1C), with a 5-bp duplication in CCNO (NM_021147.3:c.258_262dup; p.Gln88Argfs*8) being the most likely cause of ciliary aplasia. This is the first study to implicate CCNO, a DNA repair gene reported to be involved in multiciliogenesis, in PCD. In family C, we identified a similar to 3.5-kb deletion in DYX1C1, a neuronal migration gene previously associated with PCD. This is the first report of a disorder in the relatively small Irish Traveller population to be caused by 41 disease gene. Our study identified at least three different PCD genes in the Irish Traveller population, highlighting that one cannot always assume genetic homogeneity, even in small consanguineous populations.