Occurring once in every 2000 live births, craniosynostosis (CS) is the most frequent cranial birth defect. Although the genetic etiologies of syndromic CS cases are well defined, the genetic cause of Show more
Occurring once in every 2000 live births, craniosynostosis (CS) is the most frequent cranial birth defect. Although the genetic etiologies of syndromic CS cases are well defined, the genetic cause of most nonsyndromic cases remains unknown. The authors analyzed exome or RNA sequencing data from 876 children with nonsyndromic CS, including 291 case-parent trios and 585 additional probands. The authors also utilized the GeneMatcher platform and the Gabriella Miller Kids First genome sequencing project to identify additional CS patients with AXIN1 mutations. The authors describe 11 patients with nonsyndromic CS harboring rare, damaging mutations in AXIN1, an inhibitor of Wnt signaling. AXIN1 regulates signaling upstream of key mediators of osteoblast differentiation. Three of the 6 mutations identified in trios occurred de novo in the proband, while 3 were transmitted from unaffected parents. Patients with nonsyndromic CS were highly enriched for mutations in AXIN1 compared to both expectation (p = 0.0008) and exome sequencing data from > 76,000 healthy controls (p = 2.3 × 10-6), surpassing the thresholds for genome-wide significance. These findings describe the first phenotype associated with mutations in AXIN1, with mutations identified in approximately 1% of nonsyndromic CS cases. The results strengthen the existing link between Wnt signaling and maintenance of cranial suture patency and have implications for genetic testing in families with CS. Show less
In mouse models of atherosclerosis, normalization of hyperlipidemia promotes macrophage emigration and regression of atherosclerotic plaques in part by liver X receptor (LXR)-mediated induction of the Show more
In mouse models of atherosclerosis, normalization of hyperlipidemia promotes macrophage emigration and regression of atherosclerotic plaques in part by liver X receptor (LXR)-mediated induction of the chemokine receptor CCR7. Here we report that LXRα serine 198 (S198) phosphorylation modulates CCR7 expression. Low levels of S198 phosphorylation are observed in plaque macrophages in the regression environment where high levels of CCR7 expression are observed. Consistent with these findings, CCR7 gene expression in human and mouse macrophages cell lines is induced when LXRα at S198 is nonphosphorylated. In bone marrow-derived macrophages (BMDMs), we also observed induction of CCR7 by ligands that promote nonphosphorylated LXRα S198, and this was lost in LXR-deficient BMDMs. LXRα occupancy at the CCR7 promoter is enhanced and histone modifications associated with gene repression are reduced in RAW264.7 cells expressing nonphosphorylated LXRα (RAW-LXRα S198A) compared to RAW264.7 cells expressing wild-type (WT) phosphorylated LXRα (RAW-LXRα WT). Expression profiling of ligand-treated RAW-LXRα S198A cells compared to RAW-LXRα WT cells revealed induction of cell migratory and anti-inflammatory genes and repression of proinflammatory genes. Modeling of LXRα S198 in the nonphosphorylated and phosphorylated states identified phosphorylation-dependent conformational changes in the hinge region commensurate with the presence of sites for protein interaction. Therefore, gene transcription is regulated by LXRα S198 phosphorylation, including that of antiatherogenic genes such as CCR7. Show less