HIC2 regulates isoform switching during maturation of the cardiovascular system.

Physiological changes during embryonic development are associated with changes in the isoform expression of both myocyte sarcomeric proteins and of erythrocyte haemoglobins. Cell type-specific isoform expression of these genes also occurs. Although these changes appear to be coordinated, it is unclear how changes in these disparate cell types may be linked. The transcription factor Hic2 is required for normal cardiac development and the mutant is embryonic lethal. Hic2 embryos exhibit precocious expression of the definitive-lineage haemoglobin Hbb-bt in circulating primitive erythrocytes and of foetal isoforms of cardiomyocyte genes (creatine kinase, Ckm, and eukaryotic elongation factor Eef1a2) as well as ectopic cardiac expression of fast-twitch skeletal muscle troponin isoforms. We propose that HIC2 regulates a switching event within both the contractile machinery of cardiomyocytes and the oxygen carrying systems during the developmental period where demands on cardiac loading change rapidly

Restoring the Final Frontier: Exosomal MicroRNA and Cutaneous Wound Repair

Non-healing wounds present a major healthcare challenge associated with the ageing population, the rising incidence of diabetes and the obesity epidermic. Driven by the need to expand therapeutic options for the treatment of such wounds, a large body of evidence has emerged in recent years demonstrating that microRNAs (miRNAs) modulate various aspects of cutaneous wound healing through effects on diverse cell types, including keratinocytes, fibroblasts, endothelial cells and macrophages. However, clear translational pathways for non-invasive cutaneous delivery of miRNAs to facilitate wound repair have not yet been established. The recognition that miRNAs can be actively partitioned into extracellular vesicles (EVs)—exosomes, microvesicles and apoptotic bodies—has stimulated research into the regulation, function and translational exploitation of EV-derived miRNAs both as a novel mode of intercellular signalling and as a tool for miRNA transfer to cells for therapeutic purposes. In particular, because mesenchymal stem cells (MSCs) were found to support wound healing, there is much interest in the therapeutic potential of EVs, especially exosomes, derived from these cells. In this review, we survey some of the main mesenchymal stem cells (MSCs) for which exosomal miRNAs have been evaluated in the context of skin repair, including exosomes from adipose-derived MSCs, bone MSCs, amniotic MSCs and umbilical cord MSCs. Epithelial stem cell (EPSC)-derived exosomes are also considered, from keratinocytes and epidermal stem cells. The picture that emerges from studies on exosomes from various cell types reveal they share a limited set of exosomal miRNAs enhancing wound repair. We suggest a need for direct comparison of exosomal miRNA profiles from a range of MSCs and EPSCs. The ability of exogenous exosomal miRNAs to promote healing of chronic diabetic wounds also warrants further attention in order to more fully establish their therapeutic potential

Brn3a and Islet1 Act Epistatically to Regulate the Gene Expression Program of Sensory Differentiation

The combinatorial expression of transcription factors frequently marks cellular identity in the nervous system, yet how these factors interact to determine specific neuronal phenotypes is not well understood. Sensory neurons of the trigeminal ganglion (TG) and dorsal root ganglia (DRG) coexpress the homeodomain transcription factors Brn3a and Islet1, and past work has revealed partially overlapping programs of gene expression downstream of these factors. Here we examine sensory development in Brn3a/Islet1 double knock-out (DKO) mice. Sensory neurogenesis and the formation of the TG and DRG occur in DKO embryos, but the DRG are dorsally displaced, and the peripheral projections of the ganglia are markedly disturbed. Sensory neurons in DKO embryos show a profound loss of all early markers of sensory subtypes, including the Ntrk neurotrophin receptors, and the runt-family transcription factors Runx1 and Runx3. Examination of global gene expression in the E12.5 DRG of single and double mutant embryos shows that Brn3a and Islet1 are together required for nearly all aspects of sensory-specific gene expression, including several newly identified sensory markers. On a majority of targets, Brn3a and Islet1 exhibit negative epistasis, in which the effects of the individual knock-out alleles are less than additive in the DKO. Smaller subsets of targets exhibit positive epistasis, or are regulated exclusively by one factor. Brn3a/Islet1 double mutants also fail to developmentally repress neurogenic bHLH genes, and in vivo chromatin immunoprecipitation shows that Islet1 binds to a known Brn3a-regulated enhancer in the neurod4 gene, suggesting a mechanism of interaction between these genes

Are there foetal extracellular vesicles in maternal blood? Prospects for diagnostic biomarker discovery

Prenatal diagnosis of congenital disease improves clinical outcomes; however, as many as 50% of congenital heart disease cases are missed by current ultrasound screening methods. This indicates a need for improved screening technology. Extracellular vesicles (EVs) have attracted enormous interest in recent years for their potential in diagnostics. EVs mediate endocrine signalling in health and disease and are known to regulate aspects of embryonic development. Here, we critically evaluate recent evidence suggesting that EVs released from the foetus are able to cross the placenta and enter the maternal circulation. Furthermore, EVs from the mother appear to be transported in the reverse direction, whilst the placenta itself acts as a source of EVs. Experimental work utilising rodent models employing either transgenically encoded reporters or application of fluorescent tracking dyes provide convincing evidence of foetal-maternal crosstalk. This is supported by clinical data demonstrating expression of placental-origin EVs in maternal blood, as well as limited evidence for the presence of foetal-origin EVs. Together, this work raises the possibility that foetal EVs present in maternal blood could be used for the diagnosis of congenital disease. We discuss the challenges faced by researchers in translating these basic science findings into a clinical non-invasive prenatal test

Direct Reprogramming of Cardiac Fibroblasts to Repair the Injured Heart

Coronary heart disease is a leading cause of mortality and morbidity. Those that survive acute myocardial infarction are at significant risk of subsequent heart failure due to fibrotic remodelling of the infarcted myocardium. By applying knowledge from the study of embryonic cardiovascular development, modern medicine offers hope for treatment of this condition through regeneration of the myocardium by direct reprogramming of fibrotic scar tissue. Here, we will review mechanisms of cell fate specification leading to the generation of cardiovascular cell types in the embryo and use this as a framework in which to understand direct reprogramming. Driving expression of a network of transcription factors, micro RNA or small molecule epigenetic modifiers can reverse epigenetic silencing, reverting differentiated cells to a state of induced pluripotency. The pluripotent state can be bypassed by direct reprogramming in which one differentiated cell type can be transdifferentiated into another. Transdifferentiating cardiac fibroblasts to cardiomyocytes requires a network of transcription factors similar to that observed in embryonic multipotent cardiac progenitors. There is some flexibility in the composition of this network. These studies raise the possibility that the failing heart could one day be regenerated by directly reprogramming cardiac fibroblasts within post-infarct scar tissue

The Functions of Long Non-Coding RNA during Embryonic Cardiovascular Development and Its Potential for Diagnosis and Treatment of Congenital Heart Disease

Congenital heart disease (CHD) arises due to errors during the embryonic development of the heart, a highly regulated process involving an interplay between cell-intrinsic transcription factor expression and intercellular signalling mediated by morphogens. Emerging evidence indicates that expression of these protein-coding genes is controlled by a plethora of previously unappreciated non-coding RNAs operating in complex feedback-control circuits. In this review, we consider the contribution of long non-coding RNA (lncRNA) to embryonic cardiovascular development before discussing applications to CHD diagnostics and therapeutics. We discuss the process of lineage restriction during cardiovascular progenitor cell differentiation, as well as the subsequent patterning of the cardiogenic progenitor fields, taking as an example the regulation of NODAL signalling in left-right patterning of the heart. lncRNA are a highly versatile group. Nuclear lncRNA can target specific genomic sequences and recruit chromatin remodelling complexes. Some nuclear lncRNA are transcribed from enhancers and regulate chromatin looping. Cytoplasmic lncRNA act as endogenous competitors for micro RNA, as well as binding and sequestering signalling proteins. We discuss features of lncRNA that limit their study by conventional methodology and suggest solutions to these problems

A Time to Heal: MicroRNA and Circadian Dynamics in Cutaneous Wound Repair

Many biological systems have evolved circadian rhythms based on the daily cycles of daylight and darkness on Earth. Such rhythms are synchronised or entrained to 24-hour cycles, predominantly by light, and disruption of the normal circadian rhythms has been linked to elevation of multiple health risks. The skin serves as a protective barrier to prevent microbial infection and maintain homeostasis of the underlying tissue and the whole organism. However, in chronic non-healing wounds such as diabetic foot ulcers, pressures sores, venous and arterial ulcers, a variety of factors conspire to prevent wound repair. On the other hand, keloids and hypertrophic scars arise from over-active repair mechanisms that fail to cease in a timely fashion, leading to excessive production of extracellular matrix components such as such as collagen. Recent years have seen huge increases in our understanding of the functions of microRNAs (miRNA) in wound repair. Concomitantly, there has been growing recognition of miRNA roles in circadian processes, either as regulators or targets of clock activity or direct responders to external circadian stimuli. In addition, miRNAs are now known to function as intercellular signalling mediators through extracellular vesicles. In this review, we explore the intersection of mechanisms by which circadian and miRNA responses interact with each other in relation to wound repair in the skin, using keratinocytes, macrophages and fibroblasts as exemplars. We highlight areas for further investigation to support the development of translational insights to support circadian medicine in the context of these cells

A qualitative study of the experiences and expectations of women receiving in-patient postnatal care in one English maternity unit

Background Studies consistently highlight in-patient postnatal care as the area of maternity care women are least satisfied with. As part of a quality improvement study to promote a continuum of care from the birthing room to discharge home from hospital, we explored women’s expectations and experiences of current inpatient care. Methods For this part of the study, qualitative data from semi-structured interviews were transcribed and analysed using content analyses to identify issues and concepts. Women were recruited from two postnatal wards in one large maternity unit in the South of England, with around 6,000 births a year. Results Twenty women, who had a vaginal or caesarean birth, were interviewed on the postnatal ward. Identified themes included; the impact of the ward environment; the impact of the attitude of staff; quality and level of support for breastfeeding; unmet information needs; and women’s low expectations of hospital based postnatal care. Findings informed revision to the content and planning of in-patient postnatal care, results of which will be reported elsewhere. Conclusions Women’s responses highlighted several areas where changes could be implemented. Staff should be aware that how they inter-act with women could make a difference to care as a positive or negative experience. The lack of support and inconsistent advice on breastfeeding highlights that units need to consider how individual staff communicate information to women. Units need to address how and when information on practical aspects of infant care is provided if women and their partners are to feel confident on the woman’s transfer home from hospital

A Requirement for Zic2 in the Regulation of Nodal Expression Underlies the Establishment of Left-Sided Identity

ZIC2 mutation is known to cause holoprosencephaly (HPE). A subset of ZIC2 HPE probands harbour cardiovascular and visceral anomalies suggestive of laterality defects. 3D-imaging of novel mouse Zic2 mutants uncovers, in addition to HPE, laterality defects in lungs, heart, vasculature and viscera. A strong bias towards right isomerism indicates a failure to establish left identity in the lateral plate mesoderm (LPM), a phenotype that cannot be explained simply by the defective ciliogenesis previously noted in Zic2 mutants. Gene expression analysis showed that the left-determining NODAL-dependent signalling cascade fails to be activated in the LPM, and that the expression of Nodal at the node, which normally triggers this event, is itself defective in these embryos. Analysis of ChiP-seq data, in vitro transcriptional assays and mutagenesis reveals a requirement for a low-affinity ZIC2 binding site for the activation of the Nodal enhancer HBE, which is normally active in node precursor cells. These data show that ZIC2 is required for correct Nodal expression at the node and suggest a model in which ZIC2 acts at different levels to establish LR asymmetry, promoting both the production of the signal that induces left side identity and the morphogenesis of the cilia that bias its distribution

Molecular Characterization of the Mouse Superior Lateral Parabrachial Nucleus through Expression of the Transcription Factor Runx1

The ability to precisely identify separate neuronal populations is essential to the understanding of the development and function of different brain structures. This necessity is particularly evident in regions such as the brainstem, where the anatomy is quite complex and little is known about the identity, origin, and function of a number of distinct nuclei due to the lack of specific cellular markers. In this regard, the gene encoding the transcription factor Runx1 has emerged as a specific marker of restricted neuronal populations in the murine central and peripheral nervous systems. The aim of this study was to precisely characterize the expression of Runx1 in the developing and postnatal mouse brainstem.Anatomical and immunohistochemical studies were used to characterize mouse Runx1 expression in the brainstem. It is shown here that Runx1 is expressed in a restricted population of neurons located in the dorsolateral rostral hindbrain. These neurons define a structure that is ventromedial to the dorsal nucleus of the lateral lemniscus, dorsocaudal to the medial paralemniscal nucleus and rostral to the cerebellum. Runx1 expression in these cells is first observed at approximately gestational day 12.5, persists into the adult brain, and is lost in knockout mice lacking the transcription factor Atoh1, an important regulator of the development of neuronal lineages of the rhombic lip. Runx1-expressing neurons in the rostral hindbrain produce cholecystokinin and also co-express members of the Groucho/Transducin-like Enhancer of split protein family.Based on the anatomical and molecular characteristics of the Runx1-expressing cells in the rostral hindbrain, we propose that Runx1 expression in this region of the mouse brain defines the superior lateral parabrachial nucleus