Publications by authors named "Christelle Golzio"

43 Publications

Regulation of autism-relevant behaviors by cerebellar-prefrontal cortical circuits.

Nat Neurosci 2020 09 13;23(9):1102-1110. Epub 2020 Jul 13.

Departments of Otolaryngology-Head and Neck Surgery, Neurology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.

Cerebellar dysfunction has been demonstrated in autism spectrum disorders (ASDs); however, the circuits underlying cerebellar contributions to ASD-relevant behaviors remain unknown. In this study, we demonstrated functional connectivity between the cerebellum and the medial prefrontal cortex (mPFC) in mice; showed that the mPFC mediates cerebellum-regulated social and repetitive/inflexible behaviors; and showed disruptions in connectivity between these regions in multiple mouse models of ASD-linked genes and in individuals with ASD. We delineated a circuit from cerebellar cortical areas Right crus 1 (Rcrus1) and posterior vermis through the cerebellar nuclei and ventromedial thalamus and culminating in the mPFC. Modulation of this circuit induced social deficits and repetitive behaviors, whereas activation of Purkinje cells (PCs) in Rcrus1 and posterior vermis improved social preference impairments and repetitive/inflexible behaviors, respectively, in male PC-Tsc1 mutant mice. These data raise the possibility that these circuits might provide neuromodulatory targets for the treatment of ASD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41593-020-0665-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7483861PMC
September 2020

Mutations in the KIF21B kinesin gene cause neurodevelopmental disorders through imbalanced canonical motor activity.

Nat Commun 2020 05 15;11(1):2441. Epub 2020 May 15.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.

KIF21B is a kinesin protein that promotes intracellular transport and controls microtubule dynamics. We report three missense variants and one duplication in KIF21B in individuals with neurodevelopmental disorders associated with brain malformations, including corpus callosum agenesis (ACC) and microcephaly. We demonstrate, in vivo, that the expression of KIF21B missense variants specifically recapitulates patients' neurodevelopmental abnormalities, including microcephaly and reduced intra- and inter-hemispheric connectivity. We establish that missense KIF21B variants impede neuronal migration through attenuation of kinesin autoinhibition leading to aberrant KIF21B motility activity. We also show that the ACC-related KIF21B variant independently perturbs axonal growth and ipsilateral axon branching through two distinct mechanisms, both leading to deregulation of canonical kinesin motor activity. The duplication introduces a premature termination codon leading to nonsense-mediated mRNA decay. Although we demonstrate that Kif21b haploinsufficiency leads to an impaired neuronal positioning, the duplication variant might not be pathogenic. Altogether, our data indicate that impaired KIF21B autoregulation and function play a critical role in the pathogenicity of human neurodevelopmental disorder.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-020-16294-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7229210PMC
May 2020

De Novo Frameshift Variants in the Neuronal Splicing Factor NOVA2 Result in a Common C-Terminal Extension and Cause a Severe Form of Neurodevelopmental Disorder.

Am J Hum Genet 2020 04 19;106(4):438-452. Epub 2020 Mar 19.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch 67400, France; Centre National de la Recherche Scientifique, UMR7104, Illkirch 67400, France; Institut National de la Santé et de la Recherche Médicale, U964, Illkirch 67400, France; Université de Strasbourg, Illkirch 67400, France; Laboratory of Genetic Diagnostic, Hôpitaux Universitaires de Strasbourg, Strasbourg 67000, France. Electronic address:

The neuro-oncological ventral antigen 2 (NOVA2) protein is a major factor regulating neuron-specific alternative splicing (AS), previously associated with an acquired neurologic condition, the paraneoplastic opsoclonus-myoclonus ataxia (POMA). We report here six individuals with de novo frameshift variants in NOVA2 affected with a severe neurodevelopmental disorder characterized by intellectual disability (ID), motor and speech delay, autistic features, hypotonia, feeding difficulties, spasticity or ataxic gait, and abnormal brain MRI. The six variants lead to the same reading frame, adding a common proline rich C-terminal part instead of the last KH RNA binding domain. We detected 41 genes differentially spliced after NOVA2 downregulation in human neural cells. The NOVA2 variant protein shows decreased ability to bind target RNA sequences and to regulate target AS events. It also fails to complement the effect on neurite outgrowth induced by NOVA2 downregulation in vitro and to rescue alterations of retinotectal axonal pathfinding induced by loss of NOVA2 ortholog in zebrafish. Our results suggest a partial loss-of-function mechanism rather than a full heterozygous loss-of-function, although a specific contribution of the novel C-terminal extension cannot be excluded.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2020.02.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7118572PMC
April 2020

A dominant vimentin variant causes a rare syndrome with premature aging.

Eur J Hum Genet 2020 09 17;28(9):1218-1230. Epub 2020 Feb 17.

Centre Hospitalier Universitaire de Nantes, Service de Génétique Médicale, 9 quai Moncousu, 44093, Nantes, France.

Progeroid syndromes are a group of rare genetic disorders, which mimic natural aging. Unraveling the molecular defects in such conditions could impact our understanding of age-related syndromes such as Alzheimer's or cardiovascular diseases. Here we report a de novo heterozygous missense variant in the intermediate filament vimentin (c.1160 T > C; p.(Leu387Pro)) causing a multisystem disorder associated with frontonasal dysostosis and premature aging in a 39-year-old individual. Human vimentin p.(Leu387Pro) expression in zebrafish perturbed body fat distribution, and craniofacial and peripheral nervous system development. In addition, studies in patient-derived and transfected cells revealed that the variant affects vimentin turnover and its ability to form filaments in the absence of wild-type vimentin. Vimentin p.(Leu387Pro) expression diminished the amount of peripilin and reduced lipid accumulation in differentiating adipocytes, recapitulating key patient's features in vivo and in vitro. Our data highlight the function of vimentin during development and suggest its contribution to natural aging.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41431-020-0583-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7609319PMC
September 2020

International meeting on Wolf-Hirschhorn syndrome: Update on the nosology and new insights on the pathogenic mechanisms for seizures and growth delay.

Am J Med Genet A 2020 01 25;182(1):257-267. Epub 2019 Nov 25.

S. Inmunología, HULP, Madrid, Spain.

"An International Meeting on Wolf-Hirschhorn Syndrome (WHS)" was held at The University Hospital La Paz in Madrid, Spain (October 13-14, 2017). One hundred and twenty-five people, including physicians, scientists and affected families, attended the meeting. Parent and patient advocates from the Spanish Association of WHS opened the meeting with a panel discussion to set the stage regarding their hopes and expectations for therapeutic advances. In keeping with the theme on therapeutic development, the sessions followed a progression from description of the phenotype and definition of therapeutic endpoints, to definition of genomic changes. These proceedings will review the major points of discussion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.61406DOI Listing
January 2020

Kctd13-deficient mice display short-term memory impairment and sex-dependent genetic interactions.

Hum Mol Genet 2019 05;28(9):1474-1486

Center for Human Disease Modeling and Department of Cell Biology, Duke University, Durham, NC, USA.

The 16p11.2 BP4-BP5 deletion and duplication syndromes are associated with a complex spectrum of neurodevelopmental phenotypes that includes developmental delay and autism spectrum disorder, with a reciprocal effect on head circumference, brain structure and body mass index. Mouse models of the 16p11.2 copy number variant have recapitulated some of the patient phenotypes, while studies in flies and zebrafish have uncovered several candidate contributory genes within the region, as well as complex genetic interactions. We evaluated one of these loci, KCTD13, by modeling haploinsufficiency and complete knockout in mice. In contrast to the zebrafish model, and in agreement with recent data, we found normal brain structure in heterozygous and homozygous mutants. However, recapitulating previously observed genetic interactions, we discovered sex-specific brain volumetric alterations in double heterozygous Kctd13xMvp and Kctd13xLat mice. Behavioral testing revealed a significant deficit in novel object recognition, novel location recognition and social transmission of food preference in Kctd13 mutants. These phenotypes were concomitant with a reduction in density of mature spines in the hippocampus, but potentially independent of RhoA abundance, which was unperturbed postnatally in our mutants. Furthermore, transcriptome analyses from cortex and hippocampus highlighted the dysregulation of pathways important in neurodevelopment, the most significant of which was synaptic formation. Together, these data suggest that KCTD13 contributes to the neurocognitive aspects of patients with the BP4-BP5 deletion, likely through genetic interactions with other loci.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/hmg/ddy436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6489413PMC
May 2019

Small molecule inhibition of RAS/MAPK signaling ameliorates developmental pathologies of Kabuki Syndrome.

Sci Rep 2018 Jul 17;8(1):10779. Epub 2018 Jul 17.

Center for Human Disease Modeling, Duke University School of Medicine, Durham, NC, 27701, USA.

Kabuki Syndrome (KS) is a rare disorder characterized by distinctive facial features, short stature, skeletal abnormalities, and neurodevelopmental deficits. Previously, we showed that loss of function of RAP1A, a RAF1 regulator, can activate the RAS/MAPK pathway and cause KS, an observation recapitulated in other genetic models of the disorder. These data suggested that suppression of this signaling cascade might be of therapeutic benefit for some features of KS. To pursue this possibility, we performed a focused small molecule screen of a series of RAS/MAPK pathway inhibitors, where we tested their ability to rescue disease-relevant phenotypes in a zebrafish model of the most common KS locus, kmt2d. Consistent with a pathway-driven screening paradigm, two of 27 compounds showed reproducible rescue of early developmental pathologies. Further analyses showed that one compound, desmethyl-Dabrafenib (dmDf), induced no overt pathologies in zebrafish embryos but could rescue MEK hyperactivation in vivo and, concomitantly, structural KS-relevant phenotypes in all KS zebrafish models (kmt2d, kmd6a and rap1). Mass spectrometry quantitation suggested that a 100 nM dose resulted in sub-nanomolar exposure of this inhibitor and was sufficient to rescue both mandibular and neurodevelopmental defects. Crucially, germline kmt2d mutants recapitulated the gastrulation movement defects, micrognathia and neurogenesis phenotypes of transient models; treatment with dmDf ameliorated all of them significantly. Taken together, our data reinforce a causal link between MEK hyperactivation and KS and suggest that chemical suppression of BRAF might be of potential clinical utility for some features of this disorder.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-28709-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050262PMC
July 2018

Pathogenic variants in E3 ubiquitin ligase RLIM/RNF12 lead to a syndromic X-linked intellectual disability and behavior disorder.

Mol Psychiatry 2019 11 4;24(11):1748-1768. Epub 2018 May 4.

South Australian Clinical Genetics Service, SA Pathology (at Women's and Children's Hospital), North Adelaide, SA, 5006, Australia.

RLIM, also known as RNF12, is an X-linked E3 ubiquitin ligase acting as a negative regulator of LIM-domain containing transcription factors and participates in X-chromosome inactivation (XCI) in mice. We report the genetic and clinical findings of 84 individuals from nine unrelated families, eight of whom who have pathogenic variants in RLIM (RING finger LIM domain-interacting protein). A total of 40 affected males have X-linked intellectual disability (XLID) and variable behavioral anomalies with or without congenital malformations. In contrast, 44 heterozygous female carriers have normal cognition and behavior, but eight showed mild physical features. All RLIM variants identified are missense changes co-segregating with the phenotype and predicted to affect protein function. Eight of the nine altered amino acids are conserved and lie either within a domain essential for binding interacting proteins or in the C-terminal RING finger catalytic domain. In vitro experiments revealed that these amino acid changes in the RLIM RING finger impaired RLIM ubiquitin ligase activity. In vivo experiments in rlim mutant zebrafish showed that wild type RLIM rescued the zebrafish rlim phenotype, whereas the patient-specific missense RLIM variants failed to rescue the phenotype and thus represent likely severe loss-of-function mutations. In summary, we identified a spectrum of RLIM missense variants causing syndromic XLID and affecting the ubiquitin ligase activity of RLIM, suggesting that enzymatic activity of RLIM is required for normal development, cognition and behavior.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41380-018-0065-xDOI Listing
November 2019

Endoglin interacts with VEGFR2 to promote angiogenesis.

FASEB J 2018 06 11;32(6):2934-2949. Epub 2018 Jan 11.

Division of Medical Oncology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.

Endoglin, a TGF-β coreceptor predominantly expressed in endothelial cells, plays an important role in vascular development and tumor-associated angiogenesis. However, the mechanism by which endoglin regulates angiogenesis, especially during tip cell formation, remains largely unknown. In this study, we report that endoglin promoted VEGF-induced tip cell formation. Mechanistically, endoglin interacted with VEGF receptor (VEGFR)-2 in a VEGF-dependent manner, which sustained VEGFR2 on the cell surface and prevented its degradation. Endoglin mutants deficient in the ability to interact with VEGFR2 failed to sustain VEGFR2 on the cell surface and to promote VEGF-induced tip cell formation. Further, an endoglin-targeting monoclonal antibody (mAb), TRC105, cooperated with a VEGF-A targeting mAb, bevacizumab, to inhibit VEGF signaling and tip cell formation in vitro and to inhibit tumor growth, metastasis, and tumor-associated angiogenesis in a murine tumor model. This study demonstrate a novel mechanism by which endoglin initiates and regulates VEGF-driven angiogenesis while providing a rationale for combining anti-VEGF and anti-endoglin therapy in patients with cancer.-Tian, H., Huang, J. J., Golzio, C., Gao, X., Hector-Greene, M., Katsanis, N., Blobe, G. C. Endoglin interacts with VEGFR2 to promote angiogenesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1096/fj.201700867RRDOI Listing
June 2018

The Immune Signaling Adaptor LAT Contributes to the Neuroanatomical Phenotype of 16p11.2 BP2-BP3 CNVs.

Am J Hum Genet 2017 Oct 28;101(4):564-577. Epub 2017 Sep 28.

Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland. Electronic address:

Copy-number changes in 16p11.2 contribute significantly to neuropsychiatric traits. Besides the 600 kb BP4-BP5 CNV found in 0.5%-1% of individuals with autism spectrum disorders and schizophrenia and whose rearrangement causes reciprocal defects in head size and body weight, a second distal 220 kb BP2-BP3 CNV is likewise a potent driver of neuropsychiatric, anatomical, and metabolic pathologies. These two CNVs are engaged in complex reciprocal chromatin looping, intimating a functional relationship between genes in these regions that might be relevant to pathomechanism. We assessed the drivers of the distal 16p11.2 duplication by overexpressing each of the nine encompassed genes in zebrafish. Only overexpression of LAT induced a reduction of brain proliferating cells and concomitant microcephaly. Consistently, suppression of the zebrafish ortholog induced an increase of proliferation and macrocephaly. These phenotypes were not unique to zebrafish; Lat knockout mice show brain volumetric changes. Consistent with the hypothesis that LAT dosage is relevant to the CNV pathology, we observed similar effects upon overexpression of CD247 and ZAP70, encoding members of the LAT signalosome. We also evaluated whether LAT was interacting with KCTD13, MVP, and MAPK3, major driver and modifiers of the proximal 16p11.2 600 kb BP4-BP5 syndromes, respectively. Co-injected embryos exhibited an increased microcephaly, suggesting the presence of genetic interaction. Correspondingly, carriers of 1.7 Mb BP1-BP5 rearrangements that encompass both the BP2-BP3 and BP4-BP5 loci showed more severe phenotypes. Taken together, our results suggest that LAT, besides its well-recognized function in T cell development, is a major contributor of the 16p11.2 220 kb BP2-BP3 CNV-associated neurodevelopmental phenotypes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2017.08.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5630231PMC
October 2017

Partial uniparental isodisomy of chromosome 16 unmasks a deleterious biallelic mutation in IFT140 that causes Mainzer-Saldino syndrome.

Hum Genomics 2017 07 19;11(1):16. Epub 2017 Jul 19.

Center for Human Disease Modeling, Duke University Medical Center, Durham, NC, 27701, USA.

Background: The ciliopathies represent an umbrella group of >50 clinical entities that share both clinical features and molecular etiology underscored by structural and functional defects of the primary cilium. Despite the advances in gene discovery, this group of entities continues to pose a diagnostic challenge, in part due to significant genetic and phenotypic heterogeneity and variability. We consulted a pediatric case from asymptomatic, non-consanguineous parents who presented as a suspected ciliopathy due to a constellation of retinal, renal, and skeletal findings.

Results: Although clinical panel sequencing of genes implicated in nephrotic syndromes yielded no likely causal mutation, an oligo-SNP microarray identified a ~20-Mb region of homozygosity, with no altered gene dosage, on chromosome 16p13. Intersection of the proband's phenotypes with known disease genes within the homozygous region yielded a single candidate, IFT140, encoding a retrograde intraflagellar transport protein implicated previously in several ciliopathies, including the phenotypically overlapping Mainzer-Saldino syndrome (MZSDS). Sanger sequencing yielded a maternally inherited homozygous c.634G>A; p.Gly212Arg mutation altering the exon 6 splice donor site. Functional studies in cells from the proband showed that the locus produced two transcripts: a majority message containing a mis-splicing event that caused a premature termination codon and a minority message homozygous for the p.Gly212Arg allele. Zebrafish in vivo complementation studies of the latter transcript demonstrated a loss of function effect. Finally, we conducted post-hoc trio-based whole exome sequencing studies to (a) test the possibility of other causal loci in the proband and (b) explain the Mendelian error of segregation for the IFT140 mutation. We show that the proband harbors a chromosome 16 maternal heterodisomy, with segmental isodisomy at 16p13, likely due to a meiosis I error in the maternal gamete.

Conclusions: Using clinical phenotyping combined with research-based genetic and functional studies, we have characterized a recurrent IFT140 mutation in the proband; together, these data are consistent with MZSDS. Additionally, we report a rare instance of a uniparental isodisomy unmasking a deleterious mutation to cause a ciliary disorder.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s40246-017-0111-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5517791PMC
July 2017

De Novo Disruption of the Proteasome Regulatory Subunit PSMD12 Causes a Syndromic Neurodevelopmental Disorder.

Am J Hum Genet 2017 Feb 26;100(2):352-363. Epub 2017 Jan 26.

Service de Génétique, CHU de Tours, 2 Boulevard Tonnellé, 37044 Tours, France; INSERM UMR U930, Faculté de Médecine, Université François Rabelais, 37044 Tours, France.

Degradation of proteins by the ubiquitin-proteasome system (UPS) is an essential biological process in the development of eukaryotic organisms. Dysregulation of this mechanism leads to numerous human neurodegenerative or neurodevelopmental disorders. Through a multi-center collaboration, we identified six de novo genomic deletions and four de novo point mutations involving PSMD12, encoding the non-ATPase subunit PSMD12 (aka RPN5) of the 19S regulator of 26S proteasome complex, in unrelated individuals with intellectual disability, congenital malformations, ophthalmologic anomalies, feeding difficulties, deafness, and subtle dysmorphic facial features. We observed reduced PSMD12 levels and an accumulation of ubiquitinated proteins without any impairment of proteasome catalytic activity. Our PSMD12 loss-of-function zebrafish CRISPR/Cas9 model exhibited microcephaly, decreased convolution of the renal tubules, and abnormal craniofacial morphology. Our data support the biological importance of PSMD12 as a scaffolding subunit in proteasome function during development and neurogenesis in particular; they enable the definition of a neurodevelopmental disorder due to PSMD12 variants, expanding the phenotypic spectrum of UPS-dependent disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2017.01.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5294671PMC
February 2017

Heterozygous Loss-of-Function SEC61A1 Mutations Cause Autosomal-Dominant Tubulo-Interstitial and Glomerulocystic Kidney Disease with Anemia.

Am J Hum Genet 2016 Jul;99(1):174-87

Section on Nephrology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA.

Autosomal-dominant tubulo-interstitial kidney disease (ADTKD) encompasses a group of disorders characterized by renal tubular and interstitial abnormalities, leading to slow progressive loss of kidney function requiring dialysis and kidney transplantation. Mutations in UMOD, MUC1, and REN are responsible for many, but not all, cases of ADTKD. We report on two families with ADTKD and congenital anemia accompanied by either intrauterine growth retardation or neutropenia. Ultrasound and kidney biopsy revealed small dysplastic kidneys with cysts and tubular atrophy with secondary glomerular sclerosis, respectively. Exclusion of known ADTKD genes coupled with linkage analysis, whole-exome sequencing, and targeted re-sequencing identified heterozygous missense variants in SEC61A1-c.553A>G (p.Thr185Ala) and c.200T>G (p.Val67Gly)-both affecting functionally important and conserved residues in SEC61. Both transiently expressed SEC6A1A variants are delocalized to the Golgi, a finding confirmed in a renal biopsy from an affected individual. Suppression or CRISPR-mediated deletions of sec61al2 in zebrafish embryos induced convolution defects of the pronephric tubules but not the pronephric ducts, consistent with the tubular atrophy observed in the affected individuals. Human mRNA encoding either of the two pathogenic alleles failed to rescue this phenotype as opposed to a complete rescue by human wild-type mRNA. Taken together, these findings provide a mechanism by which mutations in SEC61A1 lead to an autosomal-dominant syndromic form of progressive chronic kidney disease. We highlight protein translocation defects across the endoplasmic reticulum membrane, the principal role of the SEC61 complex, as a contributory pathogenic mechanism for ADTKD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2016.05.028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5005467PMC
July 2016

Mitochondrial Copy Number as a Biomarker for Autism?

Pediatrics 2016 04 31;137(4). Epub 2016 Mar 31.

Center for Human Disease Modeling, Duke University School of Medicine, Durham, North Carolina

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1542/peds.2016-0049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4811322PMC
April 2016

Phosphorylation of Threonine 794 on Tie1 by Rac1/PAK1 Reveals a Novel Angiogenesis Regulatory Pathway.

PLoS One 2015 5;10(10):e0139614. Epub 2015 Oct 5.

Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America; Department of Medicine, Division of Cardiology, Duke University Medical Center, Durham, North Carolina, United States of America; Duke University School of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America.

The endothelial receptor tyrosine kinase (RTK) Tie1 was discovered over 20 years ago, yet its precise function and mode of action remain enigmatic. To shed light on Tie1's role in endothelial cell biology, we investigated a potential threonine phosphorylation site within the juxtamembrane domain of Tie1. Expression of a non-phosphorylatable mutant of this site (T794A) in zebrafish (Danio rerio) significantly disrupted vascular development, resulting in fish with stunted and poorly branched intersomitic vessels. Similarly, T794A-expressing human umbilical vein endothelial cells formed significantly shorter tubes with fewer branches in three-dimensional Matrigel cultures. However, mutation of T794 did not alter Tie1 or Tie2 tyrosine phosphorylation or downstream signaling in any detectable way, suggesting that T794 phosphorylation may regulate a Tie1 function independent of its RTK properties. Although T794 is within a consensus Akt phosphorylation site, we were unable to identify a physiological activator of Akt that could induce T794 phosphorylation, suggesting that Akt is not the physiological Tie1-T794 kinase. However, the small GTPase Ras-related C3 botulinum toxin substrate 1 (Rac1), which is required for angiogenesis and capillary morphogenesis, was found to associate with phospho-T794 but not the non-phosphorylatable T794A mutant. Pharmacological activation of Rac1 induced downstream activation of p21-activated kinase (PAK1) and T794 phosphorylation in vitro, and inhibition of PAK1 abrogated T794 phosphorylation. Our results provide the first demonstration of a signaling pathway mediated by Tie1 in endothelial cells, and they suggest that a novel feedback loop involving Rac1/PAK1 mediated phosphorylation of Tie1 on T794 is required for proper angiogenesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139614PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4593579PMC
June 2016

Identification of cis-suppression of human disease mutations by comparative genomics.

Nature 2015 Aug 29;524(7564):225-9. Epub 2015 Jun 29.

Center for Human Disease Modeling, Duke University, Durham, North Carolina 27701, USA.

Patterns of amino acid conservation have served as a tool for understanding protein evolution. The same principles have also found broad application in human genomics, driven by the need to interpret the pathogenic potential of variants in patients. Here we performed a systematic comparative genomics analysis of human disease-causing missense variants. We found that an appreciable fraction of disease-causing alleles are fixed in the genomes of other species, suggesting a role for genomic context. We developed a model of genetic interactions that predicts most of these to be simple pairwise compensations. Functional testing of this model on two known human disease genes revealed discrete cis amino acid residues that, although benign on their own, could rescue the human mutations in vivo. This approach was also applied to ab initio gene discovery to support the identification of a de novo disease driver in BTG2 that is subject to protective cis-modification in more than 50 species. Finally, on the basis of our data and models, we developed a computational tool to predict candidate residues subject to compensation. Taken together, our data highlight the importance of cis-genomic context as a contributor to protein evolution; they provide an insight into the complexity of allele effect on phenotype; and they are likely to assist methods for predicting allele pathogenicity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/nature14497DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537371PMC
August 2015

Rbm8a haploinsufficiency disrupts embryonic cortical development resulting in microcephaly.

J Neurosci 2015 May;35(18):7003-18

Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710, Department of Cell Biology, Department of Neurobiology, and Duke Institute for Brain Sciences, Duke University Medical Center, Durham, North Carolina 27710

The cerebral cortex is built during embryonic neurogenesis, a period when excitatory neurons are generated from progenitors. Defects in neurogenesis can cause acute neurodevelopmental disorders, such as microcephaly (reduced brain size). Altered dosage of the 1q21.1 locus has been implicated in the etiology of neurodevelopmental phenotypes; however, the role of 1q21.1 genes in neurogenesis has remained elusive. Here, we show that haploinsufficiency for Rbm8a, an exon junction complex (EJC) component within 1q21.1, causes severe microcephaly and defective neurogenesis in the mouse. At the onset of neurogenesis, Rbm8a regulates radial glia proliferation and prevents premature neuronal differentiation. Reduced Rbm8a levels result in subsequent apoptosis of neurons, and to a lesser extent, radial glia. Hence, compared to control, Rbm8a-haploinsufficient brains have fewer progenitors and neurons, resulting in defective cortical lamination. To determine whether reciprocal dosage change of Rbm8a alters embryonic neurogenesis, we overexpressed human RBM8A in two animal models. Using in utero electroporation of mouse neocortices as well as zebrafish models, we find RBM8A overexpression does not significantly perturb progenitor number or head size. Our findings demonstrate that Rbm8a is an essential neurogenesis regulator, and add to a growing literature highlighting roles for EJC components in cortical development and neurodevelopmental pathology. Our results indicate that disruption of RBM8A may contribute to neurodevelopmental phenotypes associated with proximal 1q21.1 microdeletions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.0018-15.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420776PMC
May 2015

A Potential Contributory Role for Ciliary Dysfunction in the 16p11.2 600 kb BP4-BP5 Pathology.

Am J Hum Genet 2015 May 30;96(5):784-96. Epub 2015 Apr 30.

Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland. Electronic address:

The 16p11.2 600 kb copy-number variants (CNVs) are associated with mirror phenotypes on BMI, head circumference, and brain volume and represent frequent genetic lesions in autism spectrum disorders (ASDs) and schizophrenia. Here we interrogated the transcriptome of individuals carrying reciprocal 16p11.2 CNVs. Transcript perturbations correlated with clinical endophenotypes and were enriched for genes associated with ASDs, abnormalities of head size, and ciliopathies. Ciliary gene expression was also perturbed in orthologous mouse models, raising the possibility that ciliary dysfunction contributes to 16p11.2 pathologies. In support of this hypothesis, we found structural ciliary defects in the CA1 hippocampal region of 16p11.2 duplication mice. Moreover, by using an established zebrafish model, we show genetic interaction between KCTD13, a key driver of the mirrored neuroanatomical phenotypes of the 16p11.2 CNV, and ciliopathy-associated genes. Overexpression of BBS7 rescues head size and neuroanatomical defects of kctd13 morphants, whereas suppression or overexpression of CEP290 rescues phenotypes induced by KCTD13 under- or overexpression, respectively. Our data suggest that dysregulation of ciliopathy genes contributes to the clinical phenotypes of these CNVs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2015.04.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4570289PMC
May 2015

Mutations in the endothelin receptor type A cause mandibulofacial dysostosis with alopecia.

Am J Hum Genet 2015 Apr 12;96(4):519-31. Epub 2015 Mar 12.

INSERM UMR 1163, Institut Imagine, Paris 75015, France; Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Paris 75015, France; Service de Génétique, Hôpital Necker-Enfants Malades, AP-HP, Paris 75015, France.

The endothelin receptor type A (EDNRA) signaling pathway is essential for the establishment of mandibular identity during development of the first pharyngeal arch. We report four unrelated individuals with the syndrome mandibulofacial dysostosis with alopecia (MFDA) who have de novo missense variants in EDNRA. Three of the four individuals have the same substitution, p.Tyr129Phe. Tyr129 is known to determine the selective affinity of EDNRA for endothelin 1 (EDN1), its major physiological ligand, and the p.Tyr129Phe variant increases the affinity of the receptor for EDN3, its non-preferred ligand, by two orders of magnitude. The fourth individual has a somatic mosaic substitution, p.Glu303Lys, and was previously described as having Johnson-McMillin syndrome. The zygomatic arch of individuals with MFDA resembles that of mice in which EDNRA is ectopically activated in the maxillary prominence, resulting in a maxillary to mandibular transformation, suggesting that the p.Tyr129Phe variant causes an EDNRA gain of function in the developing upper jaw. Our in vitro and in vivo assays suggested complex, context-dependent effects of the EDNRA variants on downstream signaling. Our findings highlight the importance of finely tuned regulation of EDNRA signaling during human craniofacial development and suggest that modification of endothelin receptor-ligand specificity was a key step in the evolution of vertebrate jaws.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2015.01.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4385188PMC
April 2015

CLPB mutations cause 3-methylglutaconic aciduria, progressive brain atrophy, intellectual disability, congenital neutropenia, cataracts, movement disorder.

Am J Hum Genet 2015 Feb 15;96(2):245-57. Epub 2015 Jan 15.

Institute of Neurogenetics, University of Lübeck, 23562 Lübeck, Germany.

We studied a group of individuals with elevated urinary excretion of 3-methylglutaconic acid, neutropenia that can develop into leukemia, a neurological phenotype ranging from nonprogressive intellectual disability to a prenatal encephalopathy with progressive brain atrophy, movement disorder, cataracts, and early death. Exome sequencing of two unrelated individuals and subsequent Sanger sequencing of 16 individuals with an overlapping phenotype identified a total of 14 rare, predicted deleterious alleles in CLPB in 14 individuals from 9 unrelated families. CLPB encodes caseinolytic peptidase B homolog ClpB, a member of the AAA+ protein family. To evaluate the relevance of CLPB in the pathogenesis of this syndrome, we developed a zebrafish model and an in vitro assay to measure ATPase activity. Suppression of clpb in zebrafish embryos induced a central nervous system phenotype that was consistent with cerebellar and cerebral atrophy that could be rescued by wild-type, but not mutant, human CLPB mRNA. Consistent with these data, the loss-of-function effect of one of the identified variants (c.1222A>G [p.Arg408Gly]) was supported further by in vitro evidence with the mutant peptides abolishing ATPase function. Additionally, we show that CLPB interacts biochemically with ATP2A2, known to be involved in apoptotic processes in severe congenital neutropenia (SCN) 3 (Kostmann disease [caused by HAX1 mutations]). Taken together, mutations in CLPB define a syndrome with intellectual disability, congenital neutropenia, progressive brain atrophy, movement disorder, cataracts, and 3-methylglutaconic aciduria.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2014.12.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4320260PMC
February 2015

A novel ribosomopathy caused by dysfunction of RPL10 disrupts neurodevelopment and causes X-linked microcephaly in humans.

Genetics 2014 Oct;198(2):723-33

Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina 27710

Neurodevelopmental defects in humans represent a clinically heterogeneous group of disorders. Here, we report the genetic and functional dissection of a multigenerational pedigree with an X-linked syndromic disorder hallmarked by microcephaly, growth retardation, and seizures. Using an X-linked intellectual disability (XLID) next-generation sequencing diagnostic panel, we identified a novel missense mutation in the gene encoding 60S ribosomal protein L10 (RPL10), a locus associated previously with autism spectrum disorders (ASD); the p.K78E change segregated with disease under an X-linked recessive paradigm while, consistent with causality, carrier females exhibited skewed X inactivation. To examine the functional consequences of the p.K78E change, we modeled RPL10 dysfunction in zebrafish. We show that endogenous rpl10 expression is augmented in anterior structures, and that suppression decreases head size in developing morphant embryos, concomitant with reduced bulk translation and increased apoptosis in the brain. Subsequently, using in vivo complementation, we demonstrate that p.K78E is a loss-of-function variant. Together, our findings suggest that a mutation within the conserved N-terminal end of RPL10, a protein in close proximity to the peptidyl transferase active site of the 60S ribosomal subunit, causes severe defects in brain formation and function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1534/genetics.114.168211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4196623PMC
October 2014

CHD8 regulates neurodevelopmental pathways associated with autism spectrum disorder in neural progenitors.

Proc Natl Acad Sci U S A 2014 Oct 7;111(42):E4468-77. Epub 2014 Oct 7.

Molecular Neurogenetics Unit and Psychiatric and Neurodevelopmental Genetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA 02114; Departments of Neurology and Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142

Truncating mutations of chromodomain helicase DNA-binding protein 8 (CHD8), and of many other genes with diverse functions, are strong-effect risk factors for autism spectrum disorder (ASD), suggesting multiple mechanisms of pathogenesis. We explored the transcriptional networks that CHD8 regulates in neural progenitor cells (NPCs) by reducing its expression and then integrating transcriptome sequencing (RNA sequencing) with genome-wide CHD8 binding (ChIP sequencing). Suppressing CHD8 to levels comparable with the loss of a single allele caused altered expression of 1,756 genes, 64.9% of which were up-regulated. CHD8 showed widespread binding to chromatin, with 7,324 replicated sites that marked 5,658 genes. Integration of these data suggests that a limited array of direct regulatory effects of CHD8 produced a much larger network of secondary expression changes. Genes indirectly down-regulated (i.e., without CHD8-binding sites) reflect pathways involved in brain development, including synapse formation, neuron differentiation, cell adhesion, and axon guidance, whereas CHD8-bound genes are strongly associated with chromatin modification and transcriptional regulation. Genes associated with ASD were strongly enriched among indirectly down-regulated loci (P < 10(-8)) and CHD8-bound genes (P = 0.0043), which align with previously identified coexpression modules during fetal development. We also find an intriguing enrichment of cancer-related gene sets among CHD8-bound genes (P < 10(-10)). In vivo suppression of chd8 in zebrafish produced macrocephaly comparable to that of humans with inactivating mutations. These data indicate that heterozygous disruption of CHD8 precipitates a network of gene-expression changes involved in neurodevelopmental pathways in which many ASD-associated genes may converge on shared mechanisms of pathogenesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1405266111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210312PMC
October 2014

Disruptive CHD8 mutations define a subtype of autism early in development.

Cell 2014 Jul 3;158(2):263-276. Epub 2014 Jul 3.

Peninsula Clinical Genetics Service, Exeter EX1 2ED, UK.

Autism spectrum disorder (ASD) is a heterogeneous disease in which efforts to define subtypes behaviorally have met with limited success. Hypothesizing that genetically based subtype identification may prove more productive, we resequenced the ASD-associated gene CHD8 in 3,730 children with developmental delay or ASD. We identified a total of 15 independent mutations; no truncating events were identified in 8,792 controls, including 2,289 unaffected siblings. In addition to a high likelihood of an ASD diagnosis among patients bearing CHD8 mutations, characteristics enriched in this group included macrocephaly, distinct faces, and gastrointestinal complaints. chd8 disruption in zebrafish recapitulates features of the human phenotype, including increased head size as a result of expansion of the forebrain/midbrain and impairment of gastrointestinal motility due to a reduction in postmitotic enteric neurons. Our findings indicate that CHD8 disruptions define a distinct ASD subtype and reveal unexpected comorbidities between brain development and enteric innervation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cell.2014.06.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4136921PMC
July 2014

Novel bone morphogenetic protein signaling through Smad2 and Smad3 to regulate cancer progression and development.

FASEB J 2014 Mar 5;28(3):1248-67. Epub 2013 Dec 5.

1Duke University Medical Center, 450 Research Drive, LSRC B354, Box 91004, Durham, NC 27708, USA.

The bone morphogenetic protein (BMP) signaling pathways have important roles in embryonic development and cellular homeostasis, with aberrant BMP signaling resulting in a broad spectrum of human disease. We report that BMPs unexpectedly signal through the canonical transforming growth factor β (TGF-β)-responsive Smad2 and Smad3. BMP-induced Smad2/3 signaling occurs preferentially in embryonic cells and transformed cells. BMPs signal to Smad2/3 by stimulating complex formation between the BMP-binding TGF-β superfamily receptors, activin receptor-like kinase (ALK)3/6, and the Smad2/3 phosphorylating receptors ALK5/7. BMP signaling through Smad2 mediates, in part, dorsoventral axis patterning in zebrafish embryos, whereas BMP signaling through Smad3 facilitates cancer cell invasion. Consistent with increased BMP-mediated Smad2/3 signaling during cancer progression, Smad1/5 and Smad 2/3 signaling converge in human cancer specimens. Thus, the signaling mechanisms used by BMPs and TGF-β superfamily receptors are broader than previously appreciated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1096/fj.13-239178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3929667PMC
March 2014

SCRIB and PUF60 are primary drivers of the multisystemic phenotypes of the 8q24.3 copy-number variant.

Am J Hum Genet 2013 Nov 17;93(5):798-811. Epub 2013 Oct 17.

Division of Endocrinology, Boston Children's Hospital, Boston, MA 02115, USA; Program in Medical and Population Genetics, Broad Institute, Cambridge, MA 02115, USA.

Copy-number variants (CNVs) represent a significant interpretative challenge, given that each CNV typically affects the dosage of multiple genes. Here we report on five individuals with coloboma, microcephaly, developmental delay, short stature, and craniofacial, cardiac, and renal defects who harbor overlapping microdeletions on 8q24.3. Fine mapping localized a commonly deleted 78 kb region that contains three genes: SCRIB, NRBP2, and PUF60. In vivo dissection of the CNV showed discrete contributions of the planar cell polarity effector SCRIB and the splicing factor PUF60 to the syndromic phenotype, and the combinatorial suppression of both genes exacerbated some, but not all, phenotypic components. Consistent with these findings, we identified an individual with microcephaly, short stature, intellectual disability, and heart defects with a de novo c.505C>T variant leading to a p.His169Tyr change in PUF60. Functional testing of this allele in vivo and in vitro showed that the mutation perturbs the relative dosage of two PUF60 isoforms and, subsequently, the splicing efficiency of downstream PUF60 targets. These data inform the functions of two genes not associated previously with human genetic disease and demonstrate how CNVs can exhibit complex genetic architecture, with the phenotype being the amalgam of both discrete dosage dysfunction of single transcripts and also of binary genetic interactions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2013.09.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3824129PMC
November 2013

In vivo modeling of the morbid human genome using Danio rerio.

J Vis Exp 2013 Aug 24(78):e50338. Epub 2013 Aug 24.

Center for Human Disease Modeling, Department of Cell Biology, Duke University Medical Center, USA.

Here, we present methods for the development of assays to query potentially clinically significant nonsynonymous changes using in vivo complementation in zebrafish. Zebrafish (Danio rerio) are a useful animal system due to their experimental tractability; embryos are transparent to enable facile viewing, undergo rapid development ex vivo, and can be genetically manipulated. These aspects have allowed for significant advances in the analysis of embryogenesis, molecular processes, and morphogenetic signaling. Taken together, the advantages of this vertebrate model make zebrafish highly amenable to modeling the developmental defects in pediatric disease, and in some cases, adult-onset disorders. Because the zebrafish genome is highly conserved with that of humans (~70% orthologous), it is possible to recapitulate human disease states in zebrafish. This is accomplished either through the injection of mutant human mRNA to induce dominant negative or gain of function alleles, or utilization of morpholino (MO) antisense oligonucleotides to suppress genes to mimic loss of function variants. Through complementation of MO-induced phenotypes with capped human mRNA, our approach enables the interpretation of the deleterious effect of mutations on human protein sequence based on the ability of mutant mRNA to rescue a measurable, physiologically relevant phenotype. Modeling of the human disease alleles occurs through microinjection of zebrafish embryos with MO and/or human mRNA at the 1-4 cell stage, and phenotyping up to seven days post fertilization (dpf). This general strategy can be extended to a wide range of disease phenotypes, as demonstrated in the following protocol. We present our established models for morphogenetic signaling, craniofacial, cardiac, vascular integrity, renal function, and skeletal muscle disorder phenotypes, as well as others.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3791/50338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856313PMC
August 2013

Genetic architecture of reciprocal CNVs.

Curr Opin Genet Dev 2013 Jun 5;23(3):240-8. Epub 2013 Jun 5.

Center for Human Disease Modeling, Duke University, Durham 27710, USA.

Copy number variants (CNVs) represent a frequent type of lesion in human genetic disorders that typically affects numerous genes simultaneously. This has raised the challenge of understanding which genes within a CNV drive clinical phenotypes. Although CNVs can arise by multiple mechanisms, a subset is driven by local genomic architecture permissive to recombination events that can lead to both deletions and duplications. Phenotypic analyses of patients with such reciprocal CNVs have revealed instances in which the phenotype is either identical or mirrored; strikingly, molecular studies have shown that such phenotypes are often driven by reciprocal dosage defects of the same transcript. Here we explore how these observations can help the dissection of CNVs and inform the genetic architecture of CNV-induced disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.gde.2013.04.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3740179PMC
June 2013

Exonic deletions in AUTS2 cause a syndromic form of intellectual disability and suggest a critical role for the C terminus.

Am J Hum Genet 2013 Feb 17;92(2):210-20. Epub 2013 Jan 17.

Department of Clinical Genetics, VU University Medical Center, Amsterdam 1007 MB, The Netherlands.

Genomic rearrangements involving AUTS2 (7q11.22) are associated with autism and intellectual disability (ID), although evidence for causality is limited. By combining the results of diagnostic testing of 49,684 individuals, we identified 24 microdeletions that affect at least one exon of AUTS2, as well as one translocation and one inversion each with a breakpoint within the AUTS2 locus. Comparison of 17 well-characterized individuals enabled identification of a variable syndromic phenotype including ID, autism, short stature, microcephaly, cerebral palsy, and facial dysmorphisms. The dysmorphic features were more pronounced in persons with 3'AUTS2 deletions. This part of the gene is shown to encode a C-terminal isoform (with an alternative transcription start site) expressed in the human brain. Consistent with our genetic data, suppression of auts2 in zebrafish embryos caused microcephaly that could be rescued by either the full-length or the C-terminal isoform of AUTS2. Our observations demonstrate a causal role of AUTS2 in neurocognitive disorders, establish a hitherto unappreciated syndromic phenotype at this locus, and show how transcriptional complexity can underpin human pathology. The zebrafish model provides a valuable tool for investigating the etiology of AUTS2 syndrome and facilitating gene-function analysis in the future.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2012.12.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3567268PMC
February 2013

Endoglin mediates fibronectin/α5β1 integrin and TGF-β pathway crosstalk in endothelial cells.

EMBO J 2012 Oct 31;31(19):3885-900. Epub 2012 Aug 31.

Division of Medical Oncology, Department of Medicine, Duke University Medical Center, Durham, NC, USA.

Both the transforming growth factor β (TGF-β) and integrin signalling pathways have well-established roles in angiogenesis. However, how these pathways integrate to regulate angiogenesis is unknown. Here, we show that the extracellular matrix component, fibronectin, and its cellular receptor, α5β1 integrin, specifically increase TGF-β1- and BMP-9-induced Smad1/5/8 phosphorylation via the TGF-β superfamily receptors endoglin and activin-like kinase-1 (ALK1). Fibronectin and α5β1 integrin increase Smad1/5/8 signalling by promoting endoglin/ALK1 cell surface complex formation. In a reciprocal manner, TGF-β1 activates α5β1 integrin and downstream signalling to focal adhesion kinase (FAK) in an endoglin-dependent manner. α5β1 integrin and endoglin form a complex on the cell surface and co-internalize, with their internalization regulating α5β1 integrin activation and signalling. Functionally, endoglin-mediated fibronectin/α5β1 integrin and TGF-β pathway crosstalk alter the responses of endothelial cells to TGF-β1, switching TGF-β1 from a promoter to a suppressor of migration, inhibiting TGF-β1-mediated apoptosis to promote capillary stability, and partially mediating developmental angiogenesis in vivo. These studies provide a novel mechanism for the regulation of TGF-β superfamily signalling and endothelial function through crosstalk with integrin signalling pathways.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/emboj.2012.246DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463850PMC
October 2012
-->