Identification and Characterization of FAM124B as a Novel Component of a CHD7 and CHD8 Containing Complex

Abstract

BackgroundMutations in the chromodomain helicase DNA binding protein 7 gene (CHD7) lead to CHARGE syndrome, an autosomal dominant multiple malformation disorder. Proteins involved in chromatin remodeling typically act in multiprotein complexes. We previously demonstrated that a part of human CHD7 interacts with a part of human CHD8, another chromodomain helicase DNA binding protein presumably being involved in the pathogenesis of neurodevelopmental (NDD) and autism spectrum disorders (ASD). Because identification of novel CHD7 and CHD8 interacting partners will provide further insights into the pathogenesis of CHARGE syndrome and ASD/NDD, we searched for additional associated polypeptides using the method of stable isotope labeling by amino acids in cell culture (SILAC) in combination with mass spectrometry.Principle findingsThe hitherto uncharacterized FAM124B (Family with sequence similarity 124B) was identified as a potential interaction partner of both CHD7 and CHD8. We confirmed the result by co-immunoprecipitation studies and showed a direct binding to the CHD8 part by direct yeast two hybrid experiments. Furthermore, we characterized FAM124B as a mainly nuclear localized protein with a widespread expression in embryonic and adult mouse tissues.ConclusionOur results demonstrate that FAM124B is a potential interacting partner of a CHD7 and CHD8 containing complex. From the overlapping expression pattern between Chd7 and Fam124B at murine embryonic day E12.5 and the high expression of Fam124B in the developing mouse brain, we conclude that Fam124B is a novel protein possibly involved in the pathogenesis of CHARGE syndrome and neurodevelopmental disorders.

CHD7 represses the retinoic acid synthesis enzyme ALDH1A3 during inner ear development

“…CHD7-containing complexes have been characterized in a variety of cell types, including human ESCs (PBAF), HeLa cells (WDR4, FAM124B), mouse neural progenitors (SOX2 and other proteins), and cardiomyocytes (SMAD1/5/8 and Brg1) (29,32,(39)(40)(41)(42). The lack of interaction between CHD7 and RA suggests that instead of functioning in the same large complex, CHD7 may regulate nucleosome accessibility independent of RAR/RXR heterodimers.…”

Autism‐linked CHD gene expression patterns during development predict multi‐organ disease phenotypes

“…FAM124B was reported to be a component of a CHD7‐ and CHD8‐containing complex (Batsukh et al 2010; Batsukh et al. ), suggesting that this multi‐protein complex could be functional in cells where Chd7 and Chd8 are co‐expressed. Whereas CHD7 mutations are clearly linked to multi‐organ defects in the context of CHARGE syndrome (Vissers et al.…”

“…There are also reports of scoliosis caused by CHD7 mutations (Gao et al 2007), which might relate to the expression we observed in the intersomitic mesoderm. FAM124B was reported to be a component of a CHD7-and CHD8-containing complex (Batsukh et al 2010;Batsukh et al 2012), suggesting that this multi-protein complex could be functional in cells where Chd7 and Chd8 are co-expressed. Whereas CHD7 mutations are clearly linked to multi-organ defects in the context of CHARGE syndrome (Vissers et al 2004;Gao et al 2007;Van de Laar et al 2007;Janssen et al 2012;Patten et al 2012), a clear role for CHD8 in organogenesis has not been reported.…”

CHD7 Expression Predicts Survival Outcomes in Patients with Resected Pancreatic Cancer

“…CHD7 helps to regulate neural crest gene expression (14), regulates ribosomal RNA biogenesis (15), and interacts with SOX2 to regulate gene expression (16). CHD7 is also a putative substrate of the ATM/ATR checkpoint kinases suggesting that it may play a role in the DDR (17, 18). The clinical significance of CHD7 expression in PAC has not previously been reported.…”