ABSTRACT
Congenital heart defects can be caused by mutations in genes that guide cardiac lineage formation. Here, we show deletion of NKX2-5, a critical component of the cardiac gene regulatory network, in human embryonic stem cells (hESCs), results in impaired cardiomyogenesis, failure to activate VCAM1 and to downregulate the progenitor marker PDGFRα. Furthermore, NKX2-5 null cardiomyocytes have abnormal physiology, with asynchronous contractions and altered action potentials. Molecular profiling and genetic rescue experiments demonstrate that the bHLH protein HEY2 is a key mediator of NKX2-5 function during human cardiomyogenesis. These findings identify HEY2 as a novel component of the NKX2-5 cardiac transcriptional network, providing tangible evidence that hESC models can decipher the complex pathways that regulate early stage human heart development. These data provide a human context for the evaluation of pathogenic mutations in congenital heart disease.
Subject(s)
Basic Helix-Loop-Helix Transcription Factors/genetics , Gene Regulatory Networks , Homeobox Protein Nkx-2.5/genetics , Human Embryonic Stem Cells/metabolism , Myocytes, Cardiac/metabolism , Organogenesis/genetics , Repressor Proteins/genetics , Action Potentials/physiology , Basic Helix-Loop-Helix Transcription Factors/metabolism , Cell Differentiation , Cell Line , Gene Deletion , Gene Expression Regulation, Developmental , Homeobox Protein Nkx-2.5/deficiency , Human Embryonic Stem Cells/cytology , Humans , Myocardium/cytology , Myocardium/metabolism , Myocytes, Cardiac/cytology , Patch-Clamp Techniques , Receptor, Platelet-Derived Growth Factor alpha/genetics , Receptor, Platelet-Derived Growth Factor alpha/metabolism , Repressor Proteins/metabolism , Transcription, Genetic , Vascular Cell Adhesion Molecule-1/genetics , Vascular Cell Adhesion Molecule-1/metabolismABSTRACT
In the originally published version of this Article, incorrect references were cited on two occasions in the Results section. Under the subheading 'Ca2+ activity in single dendrites and somata of L5 neurons', the final sentence of the second paragraph incorrectly cited reference 29 instead of reference 31. Under the subheading 'Spiking of L5 cell bodies is not influenced by spindles', the first sentence cited reference 30 instead of reference 29. These errors have now been corrected in both the PDF and HTML versions of the Article.
ABSTRACT
How sleep influences brain plasticity is not known. In particular, why certain electroencephalographic (EEG) rhythms are linked to memory consolidation is poorly understood. Calcium activity in dendrites is known to be necessary for structural plasticity changes, but this has never been carefully examined during sleep. Here, we report that calcium activity in populations of neocortical dendrites is increased and synchronised during oscillations in the spindle range in naturally sleeping rodents. Remarkably, the same relationship is not found in cell bodies of the same neurons and throughout the cortical column. Spindles during sleep have been suggested to be important for brain development and plasticity. Our results provide evidence for a physiological link of spindles in the cortex specific to dendrites, the main site of synaptic plasticity.Different stages of sleep, marked by particular electroencephalographic (EEG) signatures, have been linked to memory consolidation, but underlying mechanisms are poorly understood. Here, the authors show that dendritic calcium synchronisation correlates with spindle-rich sleep phases.
Subject(s)
Brain Waves , Calcium/metabolism , Dendrites/metabolism , Neocortex/metabolism , Neuronal Plasticity , Neurons/metabolism , Sleep , Animals , Cerebral Cortex , Electroencephalography , Female , Memory Consolidation , RatsABSTRACT
BACKGROUND & AIMS: Cell therapy offers the potential to treat gastrointestinal motility disorders caused by diseased or absent enteric neurons. We examined whether neurons generated from transplanted enteric neural cells provide a functional innervation of bowel smooth muscle in mice. METHODS: Enteric neural cells expressing the light-sensitive ion channel, channelrhodopsin, were isolated from the fetal or postnatal mouse bowel and transplanted into the distal colon of 3- to 4-week-old wild-type recipient mice. Intracellular electrophysiological recordings of responses to light stimulation of the transplanted cells were made from colonic smooth muscle cells in recipient mice. Electrical stimulation of endogenous enteric neurons was used as a control. RESULTS: The axons of graft-derived neurons formed a plexus in the circular muscle layer. Selective stimulation of graft-derived cells by light resulted in excitatory and inhibitory junction potentials, the electrical events underlying contraction and relaxation, respectively, in colonic muscle cells. Graft-derived excitatory and inhibitory motor neurons released the same neurotransmitters as endogenous motor neurons-acetylcholine and a combination of adenosine triphosphate and nitric oxide, respectively. Graft-derived neurons also included interneurons that provided synaptic inputs to motor neurons, but the pharmacologic properties of interneurons varied with the age of the donors from which enteric neural cells were obtained. CONCLUSIONS: Enteric neural cells transplanted into the bowel give rise to multiple functional types of neurons that integrate and provide a functional innervation of the smooth muscle of the bowel wall. Circuits composed of both motor neurons and interneurons were established, but the age at which cells are isolated influences the neurotransmitter phenotype of interneurons that are generated.
Subject(s)
Colon/innervation , Muscle, Smooth/innervation , Neurons/physiology , Neurons/transplantation , Synaptic Potentials , Acetylcholine/metabolism , Adenosine Triphosphate/metabolism , Animals , Axons/physiology , Cell- and Tissue-Based Therapy , Channelrhodopsins , Electric Stimulation , Electrophysiological Phenomena , Enteric Nervous System/physiology , Interneurons/physiology , Mice , Mice, Inbred C57BL , Motor Neurons/physiology , Neurons/metabolism , Nitric Oxide/metabolism , Optogenetics , Photic StimulationABSTRACT
Voltage-gated sodium channels (VGSCs) are fundamentally important for the generation and coordinated transmission of action potentials throughout the nervous system. It is, therefore, unsurprising that they have been shown to play a central role in the genesis and alleviation of epilepsy. Genetic studies on patients with epilepsy have identified more than 700 mutations among the genes that encode for VGSCs attesting to their role in pathogenesis. Further, many common antiepileptic drugs act on VGSCs to suppress seizure activity. Here, we present an account of the role of VGSCs in epilepsy, both through their pathogenic dysfunction and as targets for pharmacotherapy.
