技术资料

Induced pluripotent stem cells (iPSCs) offer an unlimited resource of cells to be used for the study of underlying molecular biology of disease,therapeutic drug screening,and transplant-based regenerative medicine. However,methods for the directed differentiation of skeletal muscle for these purposes remain scarce and incomplete. Here,we present a novel,small molecule-based protocol for the generation of multinucleated skeletal myotubes using eight independent iPSC lines. Through combinatorial inhibition of phosphoinositide 3-kinase (PI3K) and glycogen synthase kinase 3β (GSK3β) with addition of bone morphogenic protein 4 (BMP4) and fibroblast growth factor 2 (FGF2),we report up to 64% conversion of iPSCs into the myogenic program by day 36 as indicated by MYOG+ cell populations. These cells began to exhibit spontaneous contractions as early as 34 days in vitro in the presence of a serum-free medium formulation. We used this protocol to obtain iPSC-derived muscle cells from frontotemporal dementia (FTD) patients harboring C9orf72 hexanucleotide repeat expansions (rGGGGCC),sporadic FTD,and unaffected controls. iPSCs derived from rGGGGCC carriers contained RNA foci but did not vary in differentiation efficiency when compared to unaffected controls nor display mislocalized TDP-43 after as many as 120 days in vitro. This study presents a rapid,efficient,and transgene-free method for generating multinucleated skeletal myotubes from iPSCs and a resource for further modeling the role of skeletal muscle in amyotrophic lateral sclerosis and other motor neuron diseases. SIGNIFICANCE Protocols to produce skeletal myotubes for disease modeling or therapy are scarce and incomplete. The present study efficiently generates functional skeletal myotubes from human induced pluripotent stem cells using a small molecule-based approach. Using this strategy,terminal myogenic induction of up to 64% in 36 days and spontaneously contractile myotubes within 34 days were achieved. Myotubes derived from patients carrying the C9orf72 repeat expansion show no change in differentiation efficiency and normal TDP-43 localization after as many as 120 days in vitro when compared to unaffected controls. This study provides an efficient,novel protocol for the generation of skeletal myotubes from human induced pluripotent stem cells that may serve as a valuable tool in drug discovery and modeling of musculoskeletal and neuromuscular diseases. View Publication

MicroRNA-10b (miR-10b) is a unique oncogenic miRNA that is highly expressed in all GBM subtypes,while absent in normal neuroglial cells of the brain. miR-10b inhibition strongly impairs proliferation and survival of cultured glioma cells,including glioma-initiating stem-like cells (GSC). Although several miR-10b targets have been identified previously,the common mechanism conferring the miR-10b-sustained viability of GSC is unknown. Here,we demonstrate that in heterogeneous GSC,miR-10b regulates cell cycle and alternative splicing,often through the non-canonical targeting via 5'UTRs of its target genes,including MBNL1-3,SART3,and RSRC1. We have further assessed the inhibition of miR-10b in intracranial human GSC-derived xenograft and murine GL261 allograft models in athymic and immunocompetent mice. Three delivery routes for the miR-10b antisense oligonucleotide inhibitors (ASO),direct intratumoral injections,continuous osmotic delivery,and systemic intravenous injections,have been explored. In all cases,the treatment with miR-10b ASO led to targets' derepression,and attenuated growth and progression of established intracranial GBM. No significant systemic toxicity was observed upon ASO administration by local or systemic routes. Our results indicate that miR-10b is a promising candidate for the development of targeted therapies against all GBM subtypes. View Publication

Mouse embryonic stem cells (ESCs) can differentiate into a wide range - and possibly all cell types in vitro,and thus provide an ideal platform to study systematically the action of transcription factors (TFs) in cell differentiation. Previously,we have generated and analyzed 137 TF-inducible mouse ESC lines. As an extension of this NIA Mouse ESC Bank we generated and characterized 48 additional mouse ESC lines,in which single TFs in each line could be induced in a doxycycline-controllable manner. Together,with the previous ESC lines,the bank now comprises 185 TF-manipulable ESC lines (>10% of all mouse TFs). Global gene expression (transcriptome) profiling revealed that the induction of individual TFs in mouse ESCs for 48 hours shifts their transcriptomes toward specific differentiation fates (e.g.,neural lineages by Myt1 Isl1,and St18; mesodermal lineages by Pitx1,Pitx2,Barhl2,and Lmx1a; white blood cells by Myb,Etv2,and Tbx6,and ovary by Pitx1,Pitx2,and Dmrtc2). These data also provide and lists of inferred target genes of each TF and possible functions of these TFs. The results demonstrate the utility of mouse ESC lines and their transcriptome data for understanding the mechanism of cell differentiation and the function of TFs. View Publication

A recent study has suggested that fibroblasts can be converted into mouse-induced neural stem cells (miNSCs) through the expression of defined factors. However,successful generation of human iNSCs (hiNSCs) has proven challenging to achieve. Here,using microRNA (miRNA) expression profile analyses,we showed that let-7 microRNA has critical roles for the formation of PAX6/NESTIN-positive colonies from human adult fibroblasts and the proliferation and self-renewal of hiNSCs. HMGA2,a let-7-targeting gene,enables induction of hiNSCs that displayed morphological/molecular features and in vitro/in vivo differentiation potential similar to H9-derived NSCs. Interestingly,HMGA2 facilitated the efficient conversion of senescent somatic cells or blood CD34+ cells into hiNSCs through an interaction with SOX2,whereas other combinations or SOX2 alone showed a limited conversion ability. Taken together,these findings suggest that HMGA2/let-7 facilitates direct reprogramming toward hiNSCs in minimal conditions and maintains hiNSC self-renewal,providing a strategy for the clinical treatment of neurological diseases. View Publication

Abstract

Ideal tissue-engineered scaffold materials regulate proliferation,apoptosis and differentiation of cells seeded on them by regulating gene expression. In this study,aligned and randomly oriented collagen nanofiber scaffolds were prepared using electronic spinning technology. Their diameters and appearance reached the standards of tissue-engineered nanometer scaffolds. The nanofiber scaffolds were characterized by a high swelling ratio,high porosity and good mechanical properties. The proliferation of spinal cord-derived neural stem cells on novel nanofiber scaffolds was obviously enhanced. The proportions of cells in the S and G2/M phases noticeably increased. Moreover,the proliferation rate of neural stem cells on the aligned collagen nanofiber scaffolds was high. The expression levels of cyclin D1 and cyclin-dependent kinase 2 were increased. Bcl-2 expression was significantly increased,but Bax and caspase-3 gene expressions were obviously decreased. There was no significant difference in the differentiation of neural stem cells into neurons on aligned and randomly oriented collagen nanofiber scaffolds. These results indicate that novel nanofiber scaffolds could promote the proliferation of spinal cord-derived neural stem cells and inhibit apoptosis without inducing differentiation. Nanofiber scaffolds regulate apoptosis and proliferation in neural stem cells by altering gene expression.

Research Highlights

(1) Electronic spinning technology was used to obtain randomly oriented nanofiber membranes and aligned nanofiber membranes. The aligned and randomly oriented collagen nanometer scaffolds were shown to alter the biological behaviors of neural stem cells and induce changes in gene expression.

(2) The effects of the aligned nanofiber membranes on promoting neural stem cell proliferation and on inhibiting apoptosis of neural stem cells were better than those of the randomly oriented nanofiber membranes. Aligned and randomly oriented collagen nanometer scaffolds did not significantly induce apoptosis or differentiation in stem cells.

(3) Aligned and randomly oriented collagen nanometer scaffolds regulated the expression of apoptosis and cell cycle genes in neural stem cells.

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The role of epigenetic regulators in the control of adult neurogenesis is largely undefined. We show that the histone demethylase enzyme Kdm5b (Jarid1b) negatively regulates neurogenesis from adult subventricular zone (SVZ) neural stem cells (NSCs) in culture. shRNA-mediated depletion of Kdm5b in proliferating adult NSCs decreased proliferation rates and reduced neurosphere formation in culture. When transferred to differentiation culture conditions,Kdm5b-depleted adult NSCs migrated from neurospheres with increased velocity. Whole-genome expression screening revealed widespread transcriptional changes with Kdm5b depletion,notably the up-regulation of reelin (Reln),the inhibition of steroid biosynthetic pathway component genes and the activation of genes with intracellular transport functions in cultured adult NSCs. Kdm5b depletion increased extracellular reelin concentration in the culture medium and increased phosphorylation of the downstream reelin signaling target Disabled-1 (Dab1). Sequestration of extracellular reelin with CR-50 reelin-blocking antibodies suppressed the increase in migratory velocity of Kdm5b-depleted adult NSCs. Chromatin immunoprecipitation revealed that Kdm5b is present at the proximal promoter of Reln,and H3K4me3 methylation was increased at this locus with Kdm5b depletion in differentiating adult NSCs. Combined the data suggest Kdm5b negatively regulates neurogenesis and represses Reln in neural stem cells from the adult SVZ. View Publication

We examined the interaction between OSU-03012 (also called AR-12) with phosphodiesterase 5 (PDE5) inhibitors to determine the role of the chaperone glucose-regulated protein (GRP78)/BiP/HSPA5 in the cellular response. Sildenafil (Viagra) interacted in a greater than additive fashion with OSU-03012 to kill stem-like GBM cells. Treatment of cells with OSU-03012/sildenafil: abolished the expression of multiple oncogenic growth factor receptors and plasma membrane drug efflux pumps and caused a rapid degradation of GRP78 and other HSP70 and HSP90 family chaperone proteins. Decreased expression of plasma membrane receptors and drug efflux pumps was dependent upon enhanced PERK-eIF2α-ATF4-CHOP signaling and was blocked by GRP78 over-expression. In vivo OSU-03012/sildenafil was more efficacious than treatment with celecoxib and sildenafil at killing tumor cells without damaging normal tissues and in parallel reduced expression of ABCB1 and ABCG2 in the normal brain. The combination of OSU-03012/sildenafil synergized with low concentrations of sorafenib to kill tumor cells,and with lapatinib to kill ERBB1 over-expressing tumor cells. In multiplex assays on plasma and human tumor tissue from an OSU-03012/sildenafil treated mouse,we noted a profound reduction in uPA signaling and identified FGF and JAK1/2 as response biomarkers for potentially suppressing the killing response. Inhibition of FGFR signaling and to a lesser extent JAK1/2 signaling profoundly enhanced OSU-03012/sildenafil lethality. View Publication

Increasing evidence suggests that cellular stress may underlie mood disorders such as bipolar disorder and major depression,particularly as lithium and its targets can protect against neuronal cell death. Here we describe N-methyl-D-aspartate (NMDA)-induced filamentous actin reorganization (NIFAR) as a useful in-vitro model for studying acute neurocellular stress and investigating the effects of mood stabilizers. Brief incubation of cultured neurons with NMDA (50 µM,5 min) induces marked reorganization of F-actin within the somatodendritic domain of a majority of neurons. During NIFAR,F-actin is rapidly depleted from dendritic spines and aberrantly aggregates within the dendrite shaft. The widely used mood stabilizer lithium chloride prevented NIFAR in a time-dependent and dose-dependent manner,consistent with its known efficacy in treating bipolar disorder. Inhibitors of the lithium target glycogen synthase kinase 3 and its upstream activator phosphoinositide-3-kinase also prevented NIFAR. The antidepressant compounds imipramine and fluoxetine also attenuated NIFAR. These findings have potential relevance to neuropsychiatric diseases characterized by excessive glutamate receptor activity and synaptotoxicity. We propose that protection of the dendritic actin cytoskeleton may be a common mechanism shared by various mood stabilizers. View Publication

A current model posits that cofilin-dependent actin severing negatively impacts dendritic spine volume. Studies suggested that increased cofilin activity underlies activity-dependent spine shrinkage,and that reduced cofilin activity induces activity-dependent spine growth. We suggest instead that both types of structural plasticity correlate with decreased cofilin activity. However,the mechanism of inhibition determines the outcome for spine morphology. RNAi in rat hippocampal cultures demonstrates that cofilin is essential for normal spine maintenance. Cofilin-F-actin binding and filament barbed-end production decrease during the early phase of activity-dependent spine shrinkage; cofilin concentration also decreases. Inhibition of the cathepsin B/L family of proteases prevents both cofilin loss and spine shrinkage. Conversely,during activity-dependent spine growth,LIM kinase stimulates cofilin phosphorylation,which activates phospholipase D-1 to promote actin polymerization. These results implicate novel molecular mechanisms and prompt a revision of the current model for how cofilin functions in activity-dependent structural plasticity. View Publication

BACKGROUND Transplantation of enteric neural stem cells (ENSC) holds promise as a potential therapy for enteric neuropathies,including Hirschsprung disease. Delivery of transplantable cells via laparotomy has been described,but we propose a novel,minimally invasive endoscopic method of cell delivery. METHODS Enteric neural stem cells for transplantation were cultured from dissociated gut of postnatal donor mice. Twelve recipient mice,including Ednrb(-/-) mice with distal colonic aganglionosis,underwent colonoscopic injection of ENSC under direct vision using a 30-gauge Hamilton needle passed through a rigid cystoureteroscope. Cell engraftment,survival,and neuroglial differentiation were studied 1-4 weeks after the procedure. KEY RESULTS All recipient mice tolerated the procedure without complications and survived to sacrifice. Transplanted cells were found within the colonic wall in 9 of 12 recipient mice with differentiation into enteric neurons and glia. CONCLUSIONS & INFERENCES Endoscopic injection of ENSC is a safe and reliable method for cell delivery,and can be used to deliver a large number of cells to a specific area of disease. This minimally invasive endoscopic approach may prove beneficial to future human applications of cell therapy for neurointestinal disease. View Publication

BACKGROUND In glioblastoma (GBM),Id1 serves as a functional marker for self-renewing cancer stem-like cells. We investigated the mechanism by which cyclooxygenase-2 (Cox-2)-derived prostaglandin E2 (PGE2) induces Id1 and increases GBM self-renewal and radiation resistance. METHODS Mouse and human GBM cells were stimulated with dimethyl-PGE2 (dmPGE2),a stabilized form of PGE2,to test for Id1 induction. To elucidate the signal transduction pathway governing the increase in Id1,a combination of short interfering RNA knockdown and small molecule inhibitors and activators of PGE2 signaling were used. Western blotting,quantitative real-time (qRT)-PCR,and chromatin immunoprecipitation assays were employed. Sphere formation and radiation resistance were measured in cultured primary cells. Immunohistochemical analyses were carried out to evaluate the Cox-2-Id1 axis in experimental GBM. RESULTS In GBM cells,dmPGE2 stimulates the EP4 receptor leading to activation of ERK1/2 MAPK. This leads,in turn,to upregulation of the early growth response1 (Egr1) transcription factor and enhanced Id1 expression. Activation of this pathway increases self-renewal capacity and resistance to radiation-induced DNA damage,which are dependent on Id1. CONCLUSIONS In GBM,Cox-2-derived PGE2 induces Id1 via EP4-dependent activation of MAPK signaling and the Egr1 transcription factor. PGE2-mediated induction of Id1 is required for optimal tumor cell self-renewal and radiation resistance. Collectively,these findings identify Id1 as a key mediator of PGE2-dependent modulation of radiation response and lend insight into the mechanisms underlying radiation resistance in GBM patients. View Publication

Although neural stem cells (NSCs) sustain continuous neurogenesis throughout the adult lifespan of mammals,they progressively exhibit proliferation defects that contribute to a sharp reduction in subventricular neurogenesis during aging. However,little is known regarding the early age-related events in neurogenic niches. Using a fluorescence-activated cell sorting technique that allows for the prospective purification of the main neurogenic populations from the subventricular zone (SVZ),we demonstrated an early decline in adult neurogenesis with a dramatic loss of progenitor cells in 4 month-old young adult mice. Whereas the activated and quiescent NSC pools remained stable up to 12 months,the proliferative status of activated NSCs was already altered by 6 months,with an overall extension of the cell cycle resulting from a specific lengthening of G1. Whole genome analysis of activated NSCs from 2- and 6-month-old mice further revealed distinct transcriptomic and molecular signatures,as well as a modulation of the TGFβ signalling pathway. Our microarray study constitutes a cogent identification of new molecular players and signalling pathways regulating adult neurogenesis and its early modifications. View Publication