Unraveling the Role of Long Noncoding RNAs in Pluripotent Stem Cell-Based Neuronal Commitment and Neurogenesis
01 Jan 2017-pp 43-59
TL;DR: To further understand the lncRNA-mediated regulation in stage-specific development of pluripotent stem cell-derived neurons and other brain cells, potential lnc RNA signatures implicative in brain development or dysregulation are identified using data mining and analyses.
Abstract: Adult neurogenesis is primarily directed by neural progenitor cells, which reside in the subventricular zone (SVZ) and subgranular zone (SGZ) of the brain. Unfolding transcriptional heterogeneity and complexity of various neurodevelopmental stages can probe new insights into neurogenesis and neurodevelopmental disorders. Recent findings have suggested that epigenetic regulatory mechanisms in neural differentiation involve long noncoding RNAs (lncRNAs) as a new genre of regulators. Although many studies have addressed the overall consequences of the noncoding RNome (noncoding RNA content) on the genome, lesser is known about their specific roles and consequences in adult neurogenesis, neurodevelopmental stages, and onset of neuropathology. Recent advances in induced pluripotent stem cell (iPSC)-based neurological disease modeling have shed light on new avenues to investigate neuronal development as well as molecular paradigms underlying onset of neurological impairments. However, due to limited availability of brain tissues and gap in the understanding of lncRNA biomarkers in neurodevelopment, the study of lncRNA in neurogenesis still exists at its infancy. To further understand the lncRNA-mediated regulation in stage-specific development of pluripotent stem cell-derived neurons and other brain cells, we identified potential lncRNA signatures implicative in brain development or dysregulation using data mining and analyses. They may be used in monitoring disease progression and may serve as potential targets for novel therapeutic approaches.
TL;DR: Surface-associated TRAP (thrombospondin-related anonymous protein) family proteins are conserved across the phylum of apicomplexan parasites, indicating that motor-binding TRAP family members function not just in parasite motility and cell invasion but also in membrane disruption and cell egress.
TL;DR: The Encyclopedia of DNA Elements project provides new insights into the organization and regulation of the authors' genes and genome, and is an expansive resource of functional annotations for biomedical research.
Abstract: The human genome encodes the blueprint of life, but the function of the vast majority of its nearly three billion bases is unknown. The Encyclopedia of DNA Elements (ENCODE) project has systematically mapped regions of transcription, transcription factor association, chromatin structure and histone modification. These data enabled us to assign biochemical functions for 80% of the genome, in particular outside of the well-studied protein-coding regions. Many discovered candidate regulatory elements are physically associated with one another and with expressed genes, providing new insights into the mechanisms of gene regulation. The newly identified elements also show a statistical correspondence to sequence variants linked to human disease, and can thereby guide interpretation of this variation. Overall, the project provides new insights into the organization and regulation of our genes and genome, and is an expansive resource of functional annotations for biomedical research.
TL;DR: This article showed that OCT4, SOX2, NANOG, and LIN28 factors are sufficient to reprogram human somatic cells to pluripotent stem cells that exhibit the essential characteristics of embryonic stem (ES) cells.
Abstract: Somatic cell nuclear transfer allows trans-acting factors present in the mammalian oocyte to reprogram somatic cell nuclei to an undifferentiated state. We show that four factors (OCT4, SOX2, NANOG, and LIN28) are sufficient to reprogram human somatic cells to pluripotent stem cells that exhibit the essential characteristics of embryonic stem (ES) cells. These induced pluripotent human stem cells have normal karyotypes, express telomerase activity, express cell surface markers and genes that characterize human ES cells, and maintain the developmental potential to differentiate into advanced derivatives of all three primary germ layers. Such induced pluripotent human cell lines should be useful in the production of new disease models and in drug development, as well as for applications in transplantation medicine, once technical limitations (for example, mutation through viral integration) are eliminated.
TL;DR: It is proposed that this epigenetic marking system represents a fundamental regulatory mechanism that has an impact on most, if not all, chromatin-templated processes, with far-reaching consequences for cell fate decisions and both normal and pathological development.
Abstract: Chromatin, the physiological template of all eukaryotic genetic information, is subject to a diverse array of posttranslational modifications that largely impinge on histone amino termini, thereby regulating access to the underlying DNA. Distinct histone amino-terminal modifications can generate synergistic or antagonistic interaction affinities for chromatin-associated proteins, which in turn dictate dynamic transitions between transcriptionally active or transcriptionally silent chromatin states. The combinatorial nature of histone amino-terminal modifications thus reveals a “histone code” that considerably extends the information potential of the genetic code. We propose that this epigenetic marking system represents a fundamental regulatory mechanism that has an impact on most, if not all, chromatin-templated processes, with far-reaching consequences for cell fate decisions and both normal and pathological development.
TL;DR: It is demonstrated that new neurons, as defined by these markers, are generated from dividing progenitor cells in the dentate gyrus of adult humans, indicating that the human hippocampus retains its ability to generate neurons throughout life.
Abstract: The genesis of new cells, including neurons, in the adult human brain has not yet been demonstrated. This study was undertaken to investigate whether neurogenesis occurs in the adult human brain, in regions previously identified as neurogenic in adult rodents and monkeys. Human brain tissue was obtained postmortem from patients who had been treated with the thymidine analog, bromodeoxyuridine (BrdU), that labels DNA during the S phase. Using immunofluorescent labeling for BrdU and for one of the neuronal markers, NeuN, calbindin or neuron specific enolase (NSE), we demonstrate that new neurons, as defined by these markers, are generated from dividing progenitor cells in the dentate gyrus of adult humans. Our results further indicate that the human hippocampus retains its ability to generate neurons throughout life.
TL;DR: Cells of the adult mouse striatum have the capacity to divide and differentiate into neurons and astrocytes.
Abstract: Neurogenesis in the mammalian central nervous system is believed to end in the period just after birth; in the mouse striatum no new neurons are produced after the first few days after birth. In this study, cells isolated from the striatum of the adult mouse brain were induced to proliferate in vitro by epidermal growth factor. The proliferating cells initially expressed nestin, an intermediate filament found in neuroepithelial stem cells, and subsequently developed the morphology and antigenic properties of neurons and astrocytes. Newly generated cells with neuronal morphology were immunoreactive for gamma-aminobutyric acid and substance P, two neurotransmitters of the adult striatum in vivo. Thus, cells of the adult mouse striatum have the capacity to divide and differentiate into neurons and astrocytes.