Disruption of SATB2 or its long-range cis-regulation by SOX9 causes a syndromic form of Pierre Robin sequence

Abstract

Heterozygous loss-of-function (LOF) mutations in the gene encoding the DNA-binding protein, SATB2, result in micrognathia and cleft palate in both humans and mice. In three unrelated individuals, we show that translocation breakpoints (BPs) up to 896 kb 3′ of SATB2 polyadenylation site cause a phenotype which is indistinguishable from that caused by SATB2 LOF mutations. This syndrome comprises long nose, small mouth, micrognathia, cleft palate, arachnodactyly and intellectual disability. These BPs map to a gene desert between PLCL1 and SATB2. We identified three putative cis-regulatory elements (CRE1–3) using a comparative genomic approach each of which would be placed in trans relative to SATB2 by all three BPs. CRE1–3 each bind p300 and mono-methylated H3K4 consistent with enhancer function. In silico analysis suggested that CRE1–3 contain one or more conserved SOX9-binding sites, and this binding was confirmed using chromatin immunoprecipitation on cells derived from mouse embryonic pharyngeal arch. Interphase bacterial artificial chromosome fluorescence in situ hybridization measurements in embryonic craniofacial tissues showed that the orthologous region in mice exhibits Satb2 expression-dependent chromatin decondensation consistent with Satb2 being a target gene of CRE1–3. To assess their in vivo function, we made multiple stable reporter transgenic lines for each enhancer in zebrafish. CRE2 was shown to drive SATB2-like expression in the embryonic craniofacial region. This expression could be eliminated by mutating the SOX9-binding site of CRE2. These observations suggest that SATB2 and SOX9 may be acting together via complex cis-regulation to coordinate the growth of the developing jaw.

Chromatin Decondensation and T Cell Hyperresponsiveness in Diabetes-Associated Hyperglycemia

“…Histone acteyltransferases such as p300 are activated through some of these pathways, including p38 MAPK, and in turn are linked to chromatin decondensation (36–40). We found that treating unstimulated T cells from HG mice with SB203580 (p38 inhibitor) reduced the proportion of cells with decondensed chromatin to approximately the level present in control mice, indicating a role for p38 MAPK in this process.…”

Bone health and SATB2‐associated syndrome

“…In humans, skeletal abnormalities such as pectus excavatum, scoliosis, tibial bowing, and kyphosis have been reported on a few occasions . Additional individuals with SAS have been reported to have osteomalacia, osteopenia or osteoporosis suggesting a higher frequency of poor bone health outcomes in SAS . While biochemical blood markers of bone activity have not been systematically evaluated in patients with SAS to determine their value in screening for potential abnormalities of bone mineralization, alkaline phosphatase levels have been found to be elevated in at least 2 individuals .…”

Zebrafish models of orofacial clefts

“…SATB2 enhancer function was evaluated by testing each of these candidate CREs by transgenic reporter assay and generating stable lines. In a stable reporter line, CRE2 recapitulated the endogenous zebrafish satb2 expression domain within the ethmoid plate (Rainger et al, ). The activity of CRE2 was shown to be dependent on the SOX9 transcription factor (Rainger et al, ).…”