Interaction between IRF6 and TGFA Genes Contribute to the Risk of Nonsyndromic Cleft Lip/Palate

Abstract

Previous evidence from tooth agenesis studies suggested IRF6 and TGFA interact. Since tooth agenesis is commonly found in individuals with cleft lip/palate (CL/P), we used four large cohorts to evaluate if IRF6 and TGFA interaction contributes to CL/P. Markers within and flanking IRF6 and TGFA genes were tested using Taqman or SYBR green chemistries for case-control analyses in 1,000 Brazilian individuals. We looked for evidence of gene-gene interaction between IRF6 and TGFA by testing if markers associated with CL/P were overtransmitted together in the case-control Brazilian dataset and in the additional family datasets. Genotypes for an additional 142 case-parent trios from South America drawn from the Latin American Collaborative Study of Congenital Malformations (ECLAMC), 154 cases from Latvia, and 8,717 individuals from several cohorts were available for replication of tests for interaction. Tgfa and Irf6 expression at critical stages during palatogenesis was analyzed in wild type and Irf6 knockout mice. Markers in and near IRF6 and TGFA were associated with CL/P in the Brazilian cohort (p<10−6). IRF6 was also associated with cleft palate (CP) with impaction of permanent teeth (p<10−6). Statistical evidence of interaction between IRF6 and TGFA was found in all data sets (p = 0.013 for Brazilians; p = 0.046 for ECLAMC; p = 10−6 for Latvians, and p = 0.003 for the 8,717 individuals). Tgfa was not expressed in the palatal tissues of Irf6 knockout mice. IRF6 and TGFA contribute to subsets of CL/P with specific dental anomalies. Moreover, this potential IRF6-TGFA interaction may account for as much as 1% to 10% of CL/P cases. The Irf6-knockout model further supports the evidence of IRF6-TGFA interaction found in humans.

Spectrum of Dental Phenotypes in Nonsyndromic Orofacial Clefting

“…A genome-wide linkage study of families with clefting suggested genetic differences between those with and without dental anomalies (Vieira et al 2008b). Also, previous associations between cleft candidate genes/loci, including MSX1, PAX9, IRF6, ANKS6, ERBB2, ABAC4-ARHGAP29, 8q24, and 6q14, and specific patterns of dental anomalies in individuals with clefts (Vieira et al 2004;Modesto et al 2006;Vieira et al 2008a;Letra et al 2012;Yildirim et al 2012) support the hypothesis of a common genetic link between oral clefts and dental anomalies. However, they may also be partly explained by mechanical effects of the cleft and surgery if these variants affect cleft type and severity.…”

Molecular and bioenergetic differences between cells with African versus European inherited mitochondrial DNA haplogroups: Implications for population susceptibility to diseases

“…The CCR3 pathway is important in neovascularization and inflammation, with the CCR3 receptor (also known as eotaxin receptor) being expressed on eosinophils, airway epithelial cells, basophils, mast cells and T2 helper cells [71]. The CCR3 receptors can be found in the human choroidal neovascular membrane and various cancers [72–74]. In a mouse model, when CCR3 is blocked then choroidal neovascular is decreased [75].…”

“…TGF-alpha has been found in retina, neural tissues and tumors [71–73]. Abnormal interactions between TGF-alpha and the transcription factor IRF6 (interferon regulatory factor-6) are associated with tooth agenesis and cleft lip-palate development [74]. Vieira has suggested that TGF-alpha is a genetic modifier associated with developmental diseases [75].…”

Smad4-Irf6 genetic interaction and TGFβ-mediated IRF6 signaling cascade are crucial for palatal fusion in mice

“…Although heterozygous Irf6 mutant mice have normal palate formation, a combination of loss of Smad4 and inhibition of p38 MAPK only led to ~50% reduction of Irf6 expression and persistence of the MEE in ex vivo organ culture. This result suggests that there are other factors or signaling pathways that might regulate Irf6 expression in addition to SMAD4/p38 MAPK signaling pathways 1227 RESEARCH ARTICLE TGFβ-mediated Irf6 activity during palatogenesis (Ferretti et al, 2011;Letra et al, 2012). A recent study has shown that integration of IRF6 and the Notch ligand jagged 2 signaling is essential for controlling palatal adhesion and fusion during palatogenesis (Richardson et al, 2009).…”