FOXC1 and FOXC2 regulate growth plate chondrocyte maturation towards hypertrophy in the embryonic mouse limb skeleton.

The Forkhead box transcription factors FOXC1 and FOXC2 are expressed in condensing mesenchyme cells at the onset of endochondral ossification. We used the Prx1-cre mouse to ablate Foxc1 and Foxc2 in limb skeletal progenitor cells. Prx1-cre;Foxc1Δ/Δ;Foxc2Δ/Δ limbs were shorter than controls, with worsening phenotypes in distal structures.

and function in osteochondral progenitors for the progression through chondrocyte hypertrophy and mineralization of the primary ossification center.

The forkhead box transcription factor genes and are expressed in the condensing mesenchyme of the developing skeleton prior to the onset of chondrocyte differentiation. To determine the roles of these transcription factors in limb development we deleted both and in lateral plate mesoderm using the Prx1-cre mouse line. Resulting compound homozygous mice died shortly after birth with exencephaly, and malformations to this sternum and limb skeleton.

Assessment of Growth Plate Chondrocytes Proliferative Activity in Embryonic Endochondral Ossification via Ki-67 Immunofluorescence.

Cell proliferation is one of the key events that regulates organism development. In the limb, chondrocytes differentiate into a multi-layered cellular template called the growth plate. Chondrocyte proliferation is essential to provide the necessary cells that allow growth of a bone.

Loss of Foxc1 and Foxc2 function in chondroprogenitor cells disrupts endochondral ossification.

Endochondral ossification initiates the growth of the majority of the mammalian skeleton and is tightly controlled through gene regulatory networks. The forkhead box transcription factors Foxc1 and Foxc2 regulate aspects of osteoblast function in the formation of the skeleton, but their roles in chondrocytes to control endochondral ossification are less clear. Here, we demonstrate that Foxc1 expression is directly regulated by the activity of SRY (sex-determining region Y)-box 9, one of the earliest transcription factors to specify the chondrocyte lineage.

A Novel Locus Predicts Spermatogenic Recovery among Childhood Cancer Survivors Exposed to Alkylating Agents.

Exposure to high doses of alkylating agents is associated with increased risk of impaired spermatogenesis among nonirradiated male survivors of childhood cancer, but there is substantial variation in this risk. Here we conducted a genetic study for impaired spermatogenesis utilizing whole-genome sequencing data from 167 nonirradiated male childhood cancer survivors of European ancestry from the St. Jude Lifetime Cohort treated with cyclophosphamide equivalent dose (CED) ≥4,000 mg/m.

FOXC1 negatively regulates BMP-SMAD activity and Id1 expression during osteoblast differentiation.

Bone morphogenetic proteins regulate a diverse range of biological processes through their activation of SMAD1, SMAD5, or SMAD8 proteins that, in turn, regulate gene expression. These SMAD transcription factors achieve a layer of functional specificity in different cell types largely through actions with additional transcriptional regulatory molecules. In this study, we demonstrate that the forkhead box C1 (FOXC1) transcription factor can modulate bone morphogenetic protein (BMP) signaling to impair the expression of BMP4-responsive genes and prevent the efficient osteoblast differentiation.

Molecular analysis of NPAS3 functional domains and variants.

Background: NPAS3 encodes a transcription factor which has been associated with multiple human psychiatric and neurodevelopmental disorders. In mice, deletion of Npas3 was found to cause alterations in neurodevelopment, as well as a marked reduction in neurogenesis in the adult mouse hippocampus. This neurogenic deficit, alongside the reduction in cortical interneuron number, likely contributes to the behavioral and cognitive alterations observed in Npas3 knockout mice.

FOXC1 Regulates FGFR1 Isoform Switching to Promote Invasion Following TGFβ-Induced EMT.

Epithelial-to-mesenchymal transition (EMT) is an important physiologic process that drives tissue formation during development, but also contributes to disease pathogenesis, including fibrosis and cancer metastasis. Elevated expression of the transcription factor has been detected in several metastatic cancers that have undergone EMT. Therefore, mechanistic insight into the role of in the initiation of the EMT process was sought.

Muscle dysfunction caused by loss of Magel2 in a mouse model of Prader-Willi and Schaaf-Yang syndromes.

Prader-Willi syndrome is characterized by severe hypotonia in infancy, with decreased lean mass and increased fat mass in childhood followed by severe hyperphagia and consequent obesity. Scoliosis and other orthopaedic manifestations of hypotonia are common in children with Prader-Willi syndrome and cause significant morbidity. The relationships among hypotonia, reduced muscle mass and scoliosis have been difficult to establish.

Contribution of growth differentiation factor 6-dependent cell survival to early-onset retinal dystrophies.

Retinal dystrophies are predominantly caused by mutations affecting the visual phototransduction system and cilia, with few genes identified that function to maintain photoreceptor survival. We reasoned that growth factors involved with early embryonic retinal development would represent excellent candidates for such diseases. Here we show that mutations in the transforming growth factor-β (TGF-β) ligand Growth Differentiation Factor 6, which specifies the dorso-ventral retinal axis, contribute to Leber congenital amaurosis.

Initiation of early osteoblast differentiation events through the direct transcriptional regulation of Msx2 by FOXC1.

Hierarchal transcriptional regulatory networks function to control the correct spatiotemporal patterning of the mammalian skeletal system. One such factor, the forkhead box transcription factor FOXC1 is necessary for the correct formation of the axial and craniofacial skeleton. Previous studies have demonstrated that the frontal and parietal bones of the skull fail to develop in mice deficient for Foxc1.

PITX2 is involved in stress response in cultured human trabecular meshwork cells through regulation of SLC13A3.

Purpose: Mutations of the PITX2 gene cause Axenfeld-Rieger syndrome (ARS) and glaucoma. In this study, the authors investigated genes directly regulated by the PITX2 transcription factor to gain insight into the mechanisms underlying these disorders.

Methods: RNA from nonpigmented ciliary epithelium cells transfected with hormone-inducible PITX2 and activated by mifepristone was subjected to microarray analyses.

Severe molecular defects of a novel FOXC1 W152G mutation result in aniridia.

Purpose: FOXC1 mutations result in Axenfeld-Rieger syndrome, a disorder characterized by a broad spectrum of malformations of the anterior segment of the eye and an elevated risk for glaucoma. A novel FOXC1 W152G mutation was identified in a patient with aniridia. Molecular analysis was conducted to determine the functional consequences of the FOXC1 W152G mutation.

Human p32 is a novel FOXC1-interacting protein that regulates FOXC1 transcriptional activity in ocular cells.

Purpose: Mutations in the human forkhead box C1 gene (FOXC1) cause Axenfeld-Rieger (AR) malformations, often leading to glaucoma. Understanding the function of FOXC1 necessitates characterizing the proteins that interact with FOXC1. This study was undertaken to isolate FOXC1-interacting proteins and determine their effects on FOXC1.

FOXC1 is required for cell viability and resistance to oxidative stress in the eye through the transcriptional regulation of FOXO1A.

Mutations in the human FOXC1 transcription factor gene underlie Axenfeld-Rieger (AR) syndrome, a disorder characterized by anterior segment malformations in the eye and glaucoma. Through the use of an inducible FOXC1 protein, along with an intermediate protein synthesis blocker, we have determined direct targets of FOXC1 transcriptional regulation. FOXC1 regulates the expression of FOXO1A and binds to a conserved element in the FOXO1A promoter in vivo.

FGF19 is a target for FOXC1 regulation in ciliary body-derived cells.

The forkhead C1 (FOXC1) transcription factor is involved in the development and regulation of several organs, including the eye, where FOXC1 alterations cause iris, trabecular meshwork and corneal anomalies. Using nickel agarose chromatin enrichment with human anterior segment cells, we previously identified the fibroblast growth factor 19 (FGF19) locus as a gene potentially regulated by FOXC1. Here, we demonstrate that FGF19 is a direct target of FOXC1 in the eye.

Regulation of FOXC1 stability and transcriptional activity by an epidermal growth factor-activated mitogen-activated protein kinase signaling cascade.

Mutations in the FOXC1 transcription factor gene result in Axenfeld Rieger malformations, a disorder that affects the anterior segment of the eye, the teeth, and craniofacial structures. Individuals with this disorder possess an elevated risk for developing glaucoma. Previous work in our laboratory has indicated that FOXC1 transcriptional activity may be regulated by phosphorylation.

Functional interactions between FOXC1 and PITX2 underlie the sensitivity to FOXC1 gene dose in Axenfeld-Rieger syndrome and anterior segment dysgenesis.

Axenfeld-Rieger ocular dysgenesis is associated with mutations of the human PITX2 and FOXC1 genes, which encode transcription factors of the homeodomain and forkhead types, respectively. We have identified a functional link between FOXC1 and PITX2 which we propose underpins the similar Axenfeld-Rieger phenotype caused by mutations of these genes. FOXC1 and PITX2A physically interact, and this interaction requires crucial functional domains on both proteins: the C-terminal activation domain of FOXC1 and the homeodomain of PITX2.

The establishment of a predictive mutational model of the forkhead domain through the analyses of FOXC2 missense mutations identified in patients with hereditary lymphedema with distichiasis.

The FOX family of transcription factor genes is an evolutionary conserved, yet functionally diverse class of transcription factors that are important for regulation of energy homeostasis, development and oncogenesis. The proteins encoded by FOX genes are characterized by a conserved DNA-binding domain known as the forkhead domain (FHD). To date, disease-causing mutations have been identified in eight human FOX genes.

FOXC1 transcriptional regulatory activity is impaired by PBX1 in a filamin A-mediated manner.

FOXC1 mutations underlie Axenfeld-Rieger syndrome, an autosomal dominant disorder that is characterized by a spectrum of ocular and nonocular phenotypes and results in an increased susceptibility to glaucoma. Proteins interacting with FOXC1 were identified in human nonpigmented ciliary epithelial cells. Here we demonstrate that FOXC1 interacts with the actin-binding protein filamin A (FLNA).

Structural and functional analyses of disease-causing missense mutations in the forkhead domain of FOXC1.

Five missense mutations (P79L, P79T, I91S, I91T and R127H) within the forkhead DNA-binding domain of the FOXC1 transcription factor, identified in patients with Axenfeld-Rieger (AR) malformations, were studied to identify the effects of these mutations on FOXC1 structure and function. Molecular modeling and threading analyses predict that the I91S and T mutations may generate local disruptions to the structure of the forkhead domain while the R127H mutation alters the electrostatic charge of the DNA binding surface of the forkhead domain. The P79L and T mutations are not predicted to grossly perturb the structure of the forkhead domain.

FOXC1 transcriptional regulation is mediated by N- and C-terminal activation domains and contains a phosphorylated transcriptional inhibitory domain.

Mutations in the FOXC1 gene result in Axenfeld-Rieger malformations of the anterior segment of the eye and lead to an increased susceptibility of glaucoma. To understand how the FOXC1 protein may function in contributing to these malformations, we identified functional regions in FOXC1 required for nuclear localization and transcriptional regulation. Two regions in the FOXC1 forkhead domain, one rich in basic amino acid residues, and a second, highly conserved among all FOX proteins, were necessary for nuclear localization of the FOXC1 protein.