Concept: Progenitor cell
Harmine is the β-carboline alkaloid with the highest concentration in the psychotropic plant decoction Ayahuasca. In rodents, classical antidepressants reverse the symptoms of depression by stimulating neuronal proliferation. It has been shown that Ayahuasca presents antidepressant effects in patients with depressive disorder. In the present study, we investigated the effects of harmine in cell cultures containing human neural progenitor cells (hNPCs, 97% nestin-positive) derived from pluripotent stem cells. After 4 days of treatment, the pool of proliferating hNPCs increased by 71.5%. Harmine has been reported as a potent inhibitor of the dual specificity tyrosine-phosphorylation-regulated kinase (DYRK1A), which regulates cell proliferation and brain development. We tested the effect of analogs of harmine, an inhibitor of DYRK1A (INDY), and an irreversible selective inhibitor of monoamine oxidase (MAO) but not DYRK1A (pargyline). INDY but not pargyline induced proliferation of hNPCs similarly to harmine, suggesting that inhibition of DYRK1A is a possible mechanism to explain harmine effects upon the proliferation of hNPCs. Our findings show that harmine enhances proliferation of hNPCs and suggest that inhibition of DYRK1A may explain its effects upon proliferation in vitro and antidepressant effects in vivo.
During the development, tight regulation of the expansion of neural progenitor cells (NPCs) and their differentiation into neurons is crucial for normal cortical formation and function. In this study, we demonstrate that microRNA (miR)-128 regulates the proliferation and differentiation of NPCs by repressing pericentriolar material 1 (PCM1). Specifically, overexpression of miR-128 reduced NPC proliferation but promoted NPC differentiation into neurons both in vivo and in vitro. In contrast, the reduction of endogenous miR-128 elicited the opposite effects. Overexpression of miR-128 suppressed the translation of PCM1, and knockdown of endogenous PCM1 phenocopied the observed effects of miR-128 overexpression. Furthermore, concomitant overexpression of PCM1 and miR-128 in NPCs rescued the phenotype associated with miR-128 overexpression, enhancing neurogenesis but inhibiting proliferation, both in vitro and in utero. Taken together, these results demonstrate a novel mechanism by which miR-128 regulates the proliferation and differentiation of NPCs in the developing neocortex.
The use of induced pluripotent stem cells (iPSCs) has been postulated to be the most effective strategy for developing patient-specific respiratory epithelial cells, which may be valuable for lung-related cell therapy and lung tissue engineering. We generated a relatively homogeneous population of alveolar epithelial type II (AETII) and type I (AETI) cells from human iPSCs that had phenotypic properties similar to those of mature human AETII and AETI cells. We used these cells to explore whether lung tissue can be regenerated in vitro. Consistent with an AETII phenotype, we found that up to 97% of cells were positive for surfactant protein C, 95% for mucin-1, 93% for surfactant protein B, and 89% for the epithelial marker CD54. Additionally, exposing induced AETII to a Wnt/β-catenin inhibitor (IWR-1) changed the iPSC-AETII-like phenotype to a predominantly AETI-like phenotype. We found that of induced AET1 cells, more than 90% were positive for type I markers, T1α, and caveolin-1. Acellular lung matrices were prepared from whole rat or human adult lungs treated with decellularization reagents, followed by seeding these matrices with alveolar cells derived from human iPSCs. Under appropriate culture conditions, these progenitor cells adhered to and proliferated within the 3D lung tissue scaffold and displayed markers of differentiated pulmonary epithelium.
The generation of functional endodermal lineages, such as hepatocytes and pancreatic endocrine cells, from pluripotent stem cells (PSCs) remains a challenge. One strategy to enhance the purity, yield and maturity of endodermal derivatives is to expand endoderm committed stem or progenitor cell populations derived from PSCs before final differentiation. Recent studies have shown that this is in fact a viable option both for expanding pure populations of endodermal cells as well as for generating more mature derivative tissues, as highlighted in the case of pancreatic beta cells.
We examined the role of the orphan nuclear hormone receptor CoupTFI in mediating cortical development downstream of meningeal retinoic acid signaling. CoupTFI is a regulator of cortical development known to collaborate with retinoic acid (RA) signaling in other systems. To examine the interaction of CoupTFI and cortical RA signaling we utilized Foxc1-mutant mice in which defects in meningeal development lead to alterations in cortical development due to a reduction of RA signaling. By analyzing CoupTFI;Foxc1 double mutant mice we provide evidence that CoupTFI is required for RA rescue of the ventricular zone and the neurogenic phenotypes in Foxc1-mutants. We also found that overexpression of CoupTFI in Foxc1-mutants is sufficient to rescue the Foxc1-mutant cortical phenotype in part. These results suggest that CoupTFI collaborates with RA signaling to regulate both cortical ventricular zone progenitor cell behavior and cortical neurogenesis.
Gintonin is a novel ginseng-derived lysophosphatidic acid (LPA) receptor ligand. Oral administration of gintonin ameliorates learning and memory dysfunctions in Alzheimer’s disease (AD) animal models. The brain cholinergic system plays a key role in cognitive functions. The brains of AD patients show a reduction in acetylcholine concentration caused by cholinergic system impairments. However, little is known about the role of LPA in the cholinergic system. In this study, we used gintonin to investigate the effect of LPA receptor activation on the cholinergic system in vitro and in vivo using wild-type and AD animal models. Gintonin induced [Ca2+]i transient in cultured mouse hippocampal neural progenitor cells (NPCs). Gintonin-mediated [Ca2+]i transients were linked to stimulation of acetylcholine release through LPA receptor activation. Oral administration of gintonin-enriched fraction (25, 50, or 100 mg/kg, 3 weeks) significantly attenuated scopolamine-induced memory impairment. Oral administration of gintonin (25 or 50 mg/kg, 2 weeks) also significantly attenuated amyloid-β protein (Aβ)-induced cholinergic dysfunctions, such as decreased acetylcholine concentration, decreased choline acetyltransferase (ChAT) activity and immunoreactivity, and increased acetylcholine esterase (AChE) activity. In a transgenic AD mouse model, long-term oral administration of gintonin (25 or 50 mg/kg, 3 months) also attenuated ADrelated cholinergic impairments. In this study, we showed that activation of G protein-coupled LPA receptors by gintonin is coupled to the regulation of cholinergic functions. Furthermore, this study showed that gintonin could be a novel agent for the restoration of cholinergic system damages due to Aβ and could be utilized for AD prevention or therapy.
The generation of functional skeletal muscle tissues from human pluripotent stem cells (hPSCs) has not been reported. Here, we derive induced myogenic progenitor cells (iMPCs) via transient overexpression of Pax7 in paraxial mesoderm cells differentiated from hPSCs. In 2D culture, iMPCs readily differentiate into spontaneously contracting multinucleated myotubes and a pool of satellite-like cells endogenously expressing Pax7. Under optimized 3D culture conditions, iMPCs derived from multiple hPSC lines reproducibly form functional skeletal muscle tissues (iSKM bundles) containing aligned multi-nucleated myotubes that exhibit positive force-frequency relationship and robust calcium transients in response to electrical or acetylcholine stimulation. During 1-month culture, the iSKM bundles undergo increased structural and molecular maturation, hypertrophy, and force generation. When implanted into dorsal window chamber or hindlimb muscle in immunocompromised mice, the iSKM bundles survive, progressively vascularize, and maintain functionality. iSKM bundles hold promise as a microphysiological platform for human muscle disease modeling and drug development.
The suspected link between infection by Zika virus (ZIKV), a re-emerging flavivirus, and microcephaly is an urgent global health concern. The direct target cells of ZIKV in the developing human fetus are not clear. Here we show that a strain of the ZIKV, MR766, serially passaged in monkey and mosquito cells efficiently infects human neural progenitor cells (hNPCs) derived from induced pluripotent stem cells. Infected hNPCs further release infectious ZIKV particles. Importantly, ZIKV infection increases cell death and dysregulates cell-cycle progression, resulting in attenuated hNPC growth. Global gene expression analysis of infected hNPCs reveals transcriptional dysregulation, notably of cell-cycle-related pathways. Our results identify hNPCs as a direct ZIKV target. In addition, we establish a tractable experimental model system to investigate the impact and mechanism of ZIKV on human brain development and provide a platform to screen therapeutic compounds.
Autism spectrum disorders (ASD) are common, complex and heterogeneous neurodevelopmental disorders. Cellular and molecular mechanisms responsible for ASD pathogenesis have been proposed based on genetic studies, brain pathology and imaging, but a major impediment to testing ASD hypotheses is the lack of human cell models. Here, we reprogrammed fibroblasts to generate induced pluripotent stem cells, neural progenitor cells (NPCs) and neurons from ASD individuals with early brain overgrowth and non-ASD controls with normal brain size. ASD-derived NPCs display increased cell proliferation because of dysregulation of a β-catenin/BRN2 transcriptional cascade. ASD-derived neurons display abnormal neurogenesis and reduced synaptogenesis leading to functional defects in neuronal networks. Interestingly, defects in neuronal networks could be rescued by insulin growth factor 1 (IGF-1), a drug that is currently in clinical trials for ASD. This work demonstrates that selection of ASD subjects based on endophenotypes unraveled biologically relevant pathway disruption and revealed a potential cellular mechanism for the therapeutic effect of IGF-1.Molecular Psychiatry advance online publication, 5 July 2016; doi:10.1038/mp.2016.95.
Many antidepressants stimulate adult hippocampal neurogenesis, but the mechanisms by which they increase neurogenesis and modulate behavior are incompletely understood. Here we show that hippocampal bone morphogenetic protein (BMP) signaling is modulated by antidepressant treatment, and that the changes in BMP signaling mediate effects of antidepressant treatment on neural progenitor cell proliferation and behavior. Treatment with the selective serotonin reuptake inhibitor fluoxetine suppressed BMP signaling in the adult mouse hippocampus both by decreasing levels of BMP4 ligand and increasing production of the BMP inhibitor noggin. Increasing BMP signaling in the hippocampus via viral overexpression of BMP4 blocked the effects of fluoxetine on proliferation in the dentate gyrus and on depressive behavior. Conversely, inhibiting BMP signaling via viral overexpression of noggin in the hippocampus or infusion of noggin into the ventricles exerted antidepressant and anxiolytic activity along with an increase in hippocampal neurogenesis. Similarly, conditional genetic deletion of the type II BMP receptor in Ascl1-expressing cells promoted neurogenesis and reduced anxiety- and depression-like behaviors, suggesting that neural progenitor cells contribute to the effects of BMP signaling on affective behavior. These observations indicate that BMP signaling in the hippocampus regulates depressive behavior, and that decreasing BMP signaling may be required for the effects of some antidepressants. Thus BMP signaling is a new and powerful potential target for the treatment of depression.Molecular Psychiatry advance online publication, 4 October 2016; doi:10.1038/mp.2016.160.