DNA replication initiates from multiple genomic locations called replication origins. In metazoa, DNA sequence elements involved in origin specification remain elusive. Here, we examine pluripotent, primary, differentiating, and immortalized human cells, and demonstrate that a class of origins, termed core origins, is shared by different cell types and host ~80% of all DNA replication initiation events in any cell population. We detect a shared G-rich DNA sequence signature that coincides with most core origins in both human and mouse genomes. Transcription and G-rich elements can independently associate with replication origin activity. Computational algorithms show that core origins can be predicted, based solely on DNA sequence patterns but not on consensus motifs. Our results demonstrate that, despite an attributed stochasticity, core origins are chosen from a limited pool of genomic regions. Immortalization through oncogenic gene expression, but not normal cellular differentiation, results in increased stochastic firing from heterochromatin and decreased origin density at TAD borders.

Erythro-myeloid progenitors (EMPs) were recently described to arise from the yolk sac endothelium, just prior to vascular remodeling, and are the source of adult/post-natal tissue resident macrophages. Questions remain, however, concerning whether EMPs differentiate directly from the endothelium or merely pass through. We provide the first evidence in vivo that EMPs can emerge directly from endothelial cells (ECs) and demonstrate a role for these cells in vascular development. We find that EMPs express most EC markers but late EMPs and EMP-derived cells do not take up acetylated low-density lipoprotein (AcLDL), as ECs do. When the endothelium is labelled with AcLDL before EMPs differentiate, EMPs and EMP-derived cells arise that are AcLDL+. If AcLDL is injected after the onset of EMP differentiation, however, the majority of EMP-derived cells are not double labelled. We find that cell division precedes entry of EMPs into circulation, and that blood flow facilitates the transition of EMPs from the endothelium into circulation in a nitric oxide-dependent manner. In gain-of-function studies, we inject the CSF1-Fc ligand in embryos and found that this increases the number of CSF1R+ cells, which localize to the venous plexus and significantly disrupt venous remodeling. This is the first study to definitively establish that EMPs arise from the endothelium in vivo and show a role for early myeloid cells in vascular development.

Background: BRIL is a bone-specific membrane protein that is involved in osteogenesis imperfecta type V. Results: Bril transcription is activated by Sp1, Sp3, OSX, and GLI2 and by CpG demethylation. Conclusion: Regulation of Bril involves trans-acting factors integrating at conserved promoter elements and epigenetic modifications. Significance: Identification of the mechanisms governing Bril transcription is important to understand its role in skeletal biology.

Objective- Vascular fusion represents an important mechanism of vessel enlargement during development; however, its significance in postnatal vessel enlargement is still unknown. During fusion, 2 adjoining vessels merge to share 1 larger lumen. The aim of this research was to identify the molecular mechanism responsible for vascular fusion. Approach and Results- We previously showed that both low shear stress and DAPT ( N-[ N-(3,5-difluorophenacetyl)-L-alanyl]- S-phenylglycine t-butyl ester) treatment in the embryo result in a hyperfused vascular plexus and that increasing shear stress levels could prevent DAPT-induced fusion. We, therefore, investigated vascular endothelial-cadherin (VEC) phosphorylation because this is a common downstream target of low shear stress and DAPT treatment. VEC phosphorylation increases after DAPT treatment and decreased shear stress. The increased phosphorylation occurred independent of the cleavage of the Notch intracellular domain. Increasing shear stress rescues hyperfusion by DAPT treatment by causing the association of the phosphatase vascular endothelial-protein tyrosine phosphatase with VEC, counteracting VEC phosphorylation. Finally, Src (proto-oncogene tyrosine-protein kinase Src) inhibition prevents VEC phosphorylation in endothelial cells and can rescue hyperfusion induced by low shear stress and DAPT treatment. Moesin, a VEC target that was previously reported to mediate endothelial cell rearrangement during lumenization, relocalizes to cell membranes in vascular beds undergoing hyperfusion. Conclusions- This study provides the first evidence that VEC phosphorylation, induced by DAPT treatment and low shear stress, is involved in the process of fusion during vascular remodeling.

While the surgical procedure of distraction osteogenesis (DO) is very successful in the treatment of orthopedic conditions, its major limitation of slow bone formation in the distracted gap has prompted numerous attempts to understand and accelerate this slow bone formation. Interestingly, WNT/FZD signaling has been identified as a critical pathway in mediating bone formation and regeneration but has not yet been studied in the context of DO. The objective of this study was to determine the spatial and temporal localization of endogenous WNT signaling proteins at various times of bone formation in a wild-type mouse model of DO. In this study, the DO protocol performed on mice consisted of three phases: latency (5 days), distraction (12 days), and consolidation (34 days). Our immunohistochemical findings of distracted bone specimens show an increased expression of WNT ligands (WNT4 and WNT10A), receptors (FZD1 and 2, LRP5 and 6), β-catenin, and pathway antagonizers (DKK1; CTBP1 and 2; sFRP1, 2, and 4) during the distraction phase, which were then down-regulated during consolidation. This is the first published report to show an activation of the WNT pathway in DO and could help identify WNT as a potential therapeutic target in accelerating bone regeneration during DO.

BRIL (bone-restricted IFITM-like), is a short transmembrane protein expressed almost exclusively in osteoblasts. Although much is known about its bone-restricted gene expression pattern and protein biochemical and topological features, little information is available for BRIL physiological function. Two autosomal dominant forms of osteogenesis imperfecta (OI) are caused by distinct, but recurrent mutations in the BRIL gene. Yet, the underlying mechanisms by which those mutations lead to OI are still poorly understood. A previous report indicated that BRIL knockout (KO) mice had bone deformities, shortened long bones, and reproductive problems. Here we generated and systematically analyzed the skeletal phenotype of a new global Bril KO/LacZ knockin mouse model. KO mice reproduced and thrived normally up to 12 month of age. The skeletal phenotype of KO and WT littermates was assessed at embryonic (E13.5 to E18.5) and postnatal (2 days, 3 weeks, 3 months and 8 months) time-points. Embryos from E13.5 through to E18.5 showed significant X-Gal staining in all skeletal elements without any apparent patterning anomalies. Although bone deformities were never observed at any postnatal ages, minor and transient differences were noted in terms of bone length and static uCT parameters, but not systematically across all ages and genders. These changes, however, were not accompanied by significant alteration in bone material properties as assessed by a 3-point bending test. In addition, no changes were detected in circulating serum markers of bone turnover (P1NP, CTX-I, and osteocalcin). Gene expression monitoring also revealed no major impact of the loss of BRIL. Further, when mice were challenged with a surgically-induced fracture in tibia, bones repaired equally well in the KO mice as compared to WT. Finally, we showed that BRIL C-terminus is not a bona fide binding site for calcium. In conclusion, our in depth analysis suggest that skeletal patterning, bone mass accrual and remodeling in mice proceeded independent of BRIL.

Background: In preschool-aged children with, or at elevated risk for, developmental disabilities, challenges and needs arise from vulnerabilities linked to critical and newly emerging cognitive, speech, motor, behavioral, and social skills. For families, this can be a stressful period as they witness the gradual unfolding of their child's differences and await to receive care. Nationally and internationally, service delivery models during this critical period are not standardized nor are they nimble or sufficient enough, leading to long wait times, service gaps and duplications. Given these struggles, there is a need to examine whether “health coaching”, a structured educational program that is deliverable by different and more accessible means, can be effective in empowering families, by delivering information, providing social supports, and decreasing the demands on the overwhelmed health and developmental services. The primary objective is to evaluate the feasibility and the effectiveness of a coaching intervention (in comparison to usual and locally available care), for parents of children with emerging developmental delays. Method/Design: A multi-centered pragmatic randomized controlled trial design will be used. Families will be recruited from a representative sample of those awaiting publicly-funded regional child health services for children with developmental delays in four Canadian provinces. The target sample size is 392 families with children aged 1.5 to 4.5 years at recruitment date. Families will be randomly assigned to receive either the BRIGHT Coaching intervention (coach supported, hardcopy and online self-managed educational resources: 14 sessions, 2 sessions every 4 weeks for 6–9 months) or usual care that is locally available. In addition to the feasibility and acceptability measures, outcomes related to family empowerment, parental satisfaction and efficacy with caregiver competency will be evaluated at baseline, post-treatment (8 months), and follow-up (12 months). Discussion: This manuscript presents the background information, design, description of the interventions and of the protocol for the randomized controlled trial on the effectiveness of BRIGHT Coaching intervention for families of children with emerging developmental delays. Trial Registration: ClinicalTrials.gov , U.S. National Library of Medicine, National Institutes of Health #NCT03880383, 03/15/2019. Retrospectively registered.

Children with musculoskeletal conditions experience muscle weakness, difficulty walking and limitations in physical activities. Standard treatment includes physiotherapy, casting, and surgery. The use of botulinum toxins appears as a promising treatment on its own, but usually as an adjunct to other treatment modalities and as an alternative to surgery. The objectives were to establish the evidence on the effectiveness, safety and functional outcome of BTX-A in children with musculoskeletal conditions. A literature search using five electronic databases identified 24 studies that met our inclusion criteria. Two randomized clinical trials were included; most studies were case studies with small sample sizes and no control group. Improvements in gait pattern, function, range of motion, reduction of co-contractions, and avoidance of surgical procedures were found following BTX-A injections. Adverse events were not reported in 10 studies, minor adverse events were reported in 13 children and there were no severe adverse events. Additional doses appear safe. BTX-A is a promising treatment adjunct in improving functional outcomes in children with musculoskeletal conditions. Future studies including larger samples, longer follow-up periods and a comparison group are required to provide evidence on the effectiveness and safety of this drug in children with musculoskeletal conditions.