Chromodomain Helicase DNA-Binding Proteins in Stem Cells and Human Developmental Diseases

Dynamic regulation of gene expression is vital for proper cellular development and maintenance of differentiated states. Over the past 20 years, chromatin remodeling and epigenetic modifications of histones have emerged as key controllers of rapid reversible changes in gene expression. Mutations in genes encoding enzymes that modify chromatin have also been identified in a variety of human neurodevelopmental disorders, ranging from isolated intellectual disability and autism spectrum disorder to multiple congenital anomaly conditions that affect major organ systems and cause severe morbidity and mortality. In this study, we review recent evidence that chromodomain helicase DNA-binding (CHD) proteins regulate stem cell proliferation, fate, and differentiation in a wide variety of tissues and organs. We also highlight known roles of CHD proteins in human developmental diseases and present current unanswered questions about the pleiotropic effects of CHD protein complexes, their genetic targets, nucleosome sliding functions, and enzymatic effects in cells and tissues.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140206/1/scd.2014.0544.pd

Single Cell Transcriptomics Reveal Abnormalities in Neurosensory Patterning of the Chd7 Mutant Mouse Ear

The chromatin remodeling protein CHD7 is critical for proper formation of the mammalian inner ear. Humans with heterozygous pathogenic variants in CHD7 exhibit CHARGE syndrome, characterized by hearing loss and inner ear dysplasia, including abnormalities of the semicircular canals and Mondini malformations. Chd7Gt/+ heterozygous null mutant mice also exhibit dysplastic semicircular canals and hearing loss. Prior studies have demonstrated that reduced Chd7 dosage in the ear disrupts expression of genes involved in morphogenesis and neurogenesis, yet the relationships between these changes in gene expression and otic patterning are not well understood. Here, we sought to define roles for CHD7 in global regulation of gene expression and patterning in the developing mouse ear. Using single-cell multiplex qRT-PCR, we analyzed expression of 192 genes in FAC sorted cells from Pax2Cre;mT/mGFP wild type and Chd7Gt/+ mutant microdissected mouse otocysts. We found that Chd7 haploinsufficient otocysts exhibit a relative enrichment of cells adopting a neuroblast (vs. otic) transcriptional identity compared with wild type. Additionally, we uncovered disruptions in pro-sensory and pro-neurogenic gene expression with Chd7 loss, including genes encoding proteins that function in Notch signaling. Our results suggest that Chd7 is required for early cell fate decisions in the developing ear that involve highly specific aspects of otic patterning and differentiation

Whole exome resequencing reveals recessive mutations in TRAP1 in individuals with CAKUT and VACTERL association

Congenital abnormalities of the kidney and urinary tract (CAKUT) account for approximately half of children with chronic kidney disease and they are the most frequent cause of end-stage renal disease in children in the US. However, its genetic etiology remains mostly elusive. VACTERL association is a rare disorder that involves congenital abnormalities in multiple organs including the kidney and urinary tract in up to 60% of the cases. By homozygosity mapping and whole exome resequencing combined with high-throughput mutation analysis by array-based multiplex PCR and next-generation sequencing, we identified recessive mutations in the gene TNF receptor-associated protein 1 (TRAP1) in two families with isolated CAKUT and three families with VACTERL association. TRAP1 is a heat shock protein 90-related mitochondrial chaperone possibly involved in antiapoptotic and endoplasmic reticulum-stress signaling. Trap1 is expressed in renal epithelia of developing mouse kidney E13.5 and in the kidney of adult rats, most prominently in proximal tubules and in thick medullary ascending limbs of Henle’s loop. Thus, we identified mutations in TRAP1 as highly likely causing CAKUT or CAKUT in VACTERL association

The chromatin remodeling protein CHD7, mutated in CHARGE syndrome, is necessary for proper craniofacial and tracheal development

Background: Heterozygous mutations in the chromatin remodeling gene CHD7 cause CHARGE syndrome, a developmental disorder with variable craniofacial dysmorphisms and respiratory difficulties. The molecular etiologies of these malformations are not well understood. Homozygous Chd7 null mice die by E11, whereas Chd7 Gt/+ heterozygous null mice are a viable and excellent model of CHARGE. We explored skeletal phenotypes in Chd7 Gt/+ and Chd7 conditional knockout mice, using Foxg1‐Cre to delete Chd7 ( Foxg1 ‐CKO) in the developing eye, ear, nose, pharyngeal pouch, forebrain, and gut and Wnt1‐Cre ( Wnt1 ‐CKO) to delete Chd7 in migrating neural crest cells. Results: Foxg1 ‐CKO mice exhibited postnatal respiratory distress and death, dysplasia of the eye, concha, and frontal bone, hypoplastic maxillary shelves and nasal epithelia, and reduced tracheal rings. Wnt1‐ CKO mice exhibited frontal and occipital bone dysplasia, hypoplasia of the maxillary shelves and mandible, and cleft palate. In contrast, heterozygous Chd7 Gt/+ mice had apparently normal skeletal development. Conclusions: Conditional deletion of Chd7 in ectodermal and endodermal derivatives ( Foxg1‐Cre ) or migrating neural crest cells ( Wnt1‐Cre ) results in varied and more severe craniofacial defects than in Chd7 Gt/+ mice. These studies indicate that CHD7 has an important, dosage‐dependent role in development of several different craniofacial tissues. Developmental Dynamics 243:1055–1066, 2014 . © 2014 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists. Key findings: Chd7 is necessary in craniofacial ectodermal, endodermal, and neural crest cells. Loss of Chd7 in mice results in upper and lower respiratory tract anomalies which mimic human CHARGE syndrome. Chd7 is important for proper development of neural crest‐derived mesenchymal tissues contributing to bone and cartilage. Loss of Wnt1Cre‐mediated Chd7 in neural crest cells does not result in heart defects. Foxg1Cre‐mediated deletion of Chd7 leads to severe microphthalmia.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108278/1/dvdy24156.pd

The chromatin remodeling protein CHD7, mutated in CHARGE syndrome, is necessary for proper craniofacial and tracheal development

Background: Heterozygous mutations in the chromatin remodeling gene CHD7 cause CHARGE syndrome, a developmental disorder with variable craniofacial dysmorphisms and respiratory difficulties. The molecular etiologies of these malformations are not well understood. Homozygous Chd7 null mice die by E11, whereas Chd7 Gt/+ heterozygous null mice are a viable and excellent model of CHARGE. We explored skeletal phenotypes in Chd7 Gt/+ and Chd7 conditional knockout mice, using Foxg1‐Cre to delete Chd7 ( Foxg1 ‐CKO) in the developing eye, ear, nose, pharyngeal pouch, forebrain, and gut and Wnt1‐Cre ( Wnt1 ‐CKO) to delete Chd7 in migrating neural crest cells. Results: Foxg1 ‐CKO mice exhibited postnatal respiratory distress and death, dysplasia of the eye, concha, and frontal bone, hypoplastic maxillary shelves and nasal epithelia, and reduced tracheal rings. Wnt1‐ CKO mice exhibited frontal and occipital bone dysplasia, hypoplasia of the maxillary shelves and mandible, and cleft palate. In contrast, heterozygous Chd7 Gt/+ mice had apparently normal skeletal development. Conclusions: Conditional deletion of Chd7 in ectodermal and endodermal derivatives ( Foxg1‐Cre ) or migrating neural crest cells ( Wnt1‐Cre ) results in varied and more severe craniofacial defects than in Chd7 Gt/+ mice. These studies indicate that CHD7 has an important, dosage‐dependent role in development of several different craniofacial tissues. Developmental Dynamics 243:1055–1066, 2014 . © 2014 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists. Key findings: Chd7 is necessary in craniofacial ectodermal, endodermal, and neural crest cells. Loss of Chd7 in mice results in upper and lower respiratory tract anomalies which mimic human CHARGE syndrome. Chd7 is important for proper development of neural crest‐derived mesenchymal tissues contributing to bone and cartilage. Loss of Wnt1Cre‐mediated Chd7 in neural crest cells does not result in heart defects. Foxg1Cre‐mediated deletion of Chd7 leads to severe microphthalmia.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108278/1/dvdy24156.pd

Duplication 2p25 in a Child with Clinical Features of CHARGE Syndrome

CHARGE syndrome is a dominant disorder characterized by ocular colobomata, heart defects, choanal atresia, retardation of growth and development, genital hypoplasia, and ear abnormalities including deafness and vestibular disorders. The majority of individuals with CHARGE have pathogenic variants in the gene encoding CHD7, a chromatin remodeling protein. Here, we present a 15-year-old girl with clinical features of CHARGE syndrome and a de novo 6.5Mb gain of genomic material at 2p25.3-p25.2. The duplicated region contained 24 genes, including the early and broadly expressed transcription factor gene SOX11. Analysis of 28 other patients with CHARGE showed no SOX11 copy number changes or pathogenic sequence variants. To our knowledge, this child's chromosomal abnormality is unique and represents the first co-occurrence of duplication 2p25 and clinical features of CHARGE syndrome. We compare our patient's phenotype to ten previously published patients with isolated terminal duplication 2p, and elaborate on the clinical diagnosis of CHARGE in the context of atypical genetic findings. (C) 2016 Wiley Periodicals, Inc

The effect of hemorrhage control adjuncts on outcome in severe pelvic fracture: A multi-institutional study

Hemodynamically unstable patients with severe pelvic fracture are a significant challenge to trauma surgeons and have high mortality. Significant variability across institutions in hemorrhage control adjuncts used to quell pelvic bleeding has been demonstrated. However, the effect of these methods on time to definitive bleeding control, type of resuscitation given, and outcomes remains unknown. We sought to elucidate those effects. This was a multicenter retrospective review of severe pelvic fracture patients in shock between 2011 and 2016. Shock was defined as systolic blood pressure less than 90 mm Hg, heart rate greater than 120 beats per minute, or base deficit less than -5. Definitive bleeding control was defined as time to surgical control in the operating room or embolization by interventional radiology. Significance level was at p less than 0.05. A total of 279 severe pelvic fracture patients with shock on admission from 12 trauma centers were included. The cohort was primarily male (62%) with median (interquartile range) age of 40 years (28-54 years), Injury Severity Score of 38 (29-50), and Glasgow Coma Scale score of 13 (3-15). Overall mortality was 32%. The most common adjunct used was pelvic binder (50%) followed by no adjunct (30.5%); least common was resuscitative balloon occlusion of the aorta (REBOA) (2.5%). Preperitoneal packing alone and REBOA alone/with other adjunct(s) resulted in the fastest times to operating room/interventional radiology but also had the highest blood utilization and mortality rates. Resuscitative balloon occlusion of the aorta was most often used along with pelvic binder (6 of 13; 46%). Marked variation in management of severe pelvic fracture patients in shock indicates the need for a standardized approach to maximize outcomes and minimize transfusion requirements. The use of preperitoneal packing and/or REBOA yielded fastest times to definitive bleeding control. However, REBOA continues to be infrequently used. Future prospective analysis of this combination needs further validation in patients with severe pelvic hemorrhage. Therapeutic study, level IV