Protein-based direct reprogramming of fibroblasts to neuronal cells using 30Kc19 protein and transcription factor Ascl1.

Direct reprogramming of non-neural lineages to functional neurons holds great potential for neural development, neurological disease modeling, and regenerative medicine. Recent work has shown that single transcription factor Ascl1 can directly reprogram fibroblasts into neuronal cells under co-culture system with glial cells. It is confirmed that Ascl1 is the key driver in the reprogramming of induced neuronal cells (iNCs). However, most reprogramming methods use genetic materials and/or potentially mutagenic molecules to generate iNCs. Herein, we used 30Kc19 protein as a novel fusion partner of transcription factor Ascl1 to induce direct reprogramming of fibroblasts to neuronal cells. We demonstrated soluble expression and stability of Ascl1 protein was increased and maintained by co-expression with 30Kc19 protein, respectively. We confirmed that intracellular delivery of the fusion protein resulted in iNC generation. Protein-induced neuronal cells (p-iNCs) expressed neuronal protein markers (MAP2, Tuj1) and transcriptional genes (Ascl1, Brn2, and Myt1l). Protein-based direct reprogramming system eliminates the potential risk associated with the use of genetic materials. This method is anticipated to be useful for safe generation of patient-specific human neuronal cells for future applications in regenerative medicine.

Post-injury Nose-to-Brain Delivery of Activin A and SerpinB2 Reduces Brain Damage in a Mouse Stroke Model.

Synaptic NMDA receptors activating nuclear calcium-driven adaptogenomics control a potent body-own neuroprotective mechanism, referred to as acquired neuroprotection. Viral vector-mediated gene transfer in conjunction with stereotactic surgery has previously demonstrated the proficiency of several nuclear calcium-regulated genes to protect in vivo against brain damage caused by toxic extrasynaptic NMDA receptor signaling following seizures or stroke. Here we used noninvasive nose-to-brain administration of Activin A and SerpinB2, two secreted nuclear calcium-regulated neuroprotectants, for post-injury treatment of brain damage following middle cerebral artery occlusion (MCAO) in C57BL/6N mice. The observed reduction of the infarct volume was comparable to the protection obtained by intracerebroventricular injection of recombinant Activin A or SerpinB2 or by stereotactic delivery 3 weeks prior to the injury of a recombinant adeno-associated virus containing an expression cassette for the potent neuroprotective transcription factor Npas4. These results establish post-injury, nose-to-brain delivery of Activin A and SerpinB2 as effective and possibly clinically applicable treatments of acute and chronic neurodegenerative conditions.

Atoh1 gene therapy in the cochlea for hair cell regeneration.

INTRODUCTION: The sensory epithelium of the cochlea is a complex structure containing hair cells, supporting cells and auditory nerve endings, all of which degenerate after hearing loss in mammals. Biological approaches are being considered to preserve and restore the sensory epithelium after hearing loss. Of particular note is the ectopic expression of the Atoh1 gene, which has been shown to convert residual supporting cells into hair cells with restoration of function in some cases. AREAS COVERED: In this review, hair cell development, spontaneous regeneration and hair cell regeneration mediated by Atoh1 gene therapy in the cochlea are discussed. EXPERT OPINION: Gene therapy can be safely delivered locally to the inner ear and can be targeted to the sensory epithelium of the cochlea. Expression of the Atoh1 gene in supporting cells results in their transformation into cells with the appearance and function of immature hair cells but with the resulting loss of the original supporting cell. While the feasibility of Atoh1 gene therapy in the cochlea is largely dependent on the severity of the hearing loss, hearing restoration can be achieved in some situations. With further advances in Atoh1 gene therapy, hearing loss may not be as permanent as once thought.

In vivo delivery of Atoh1 gene to rat cochlea using a dendrimer-based nanocarrier.

Gene therapy is a promising clinical solution to hearing loss. However suitable gene carriers for the auditory system are currently unavailable. Given the unique structure of the inner ear, the route of delivery and gene transfer efficiency are still not optimal at present. This study presented a non-viral delivery system of in vivo delivery of Atoh1 gene (a potentially therapeutic gene for hearing loss) to rat cochlea. We treated polyamidoamine (PAMAM) dendrimers by activating and modifying with Na-carboxymethyl-beta-cyclodextrins (CM-beta-CD) in sequence. A novel gene carrier (CM-beta-CD modified activated PAMAM dendrimers, CMAP) was then constructed. CMAP nanoparticles could bind pRK5-Atoh1-EGFP plasmids to form vector-DNA complexes (dendriplexes) with a mean particle size of 132 +/- 20 nm and zeta potential of 31 +/- 3 mV. These dendriplexes were locally applied on the round window membrane and delivered to the inner ear by passive gradient permeation. Results showed that the Atoh1 gene was successfully transferred into the cells as indicated by the green fluorescence detected in the inner ear. A relatively selective gene transfer with high efficiency was achieved in the auditory hair cells but not much in other cell types in the cochlea. Auditory brainstem response was determined seven days after inoculation, indicating good tolerance. This approach may provide a novel tool for inner ear gene therapy and initiate the applications of biomaterials to treat auditory disorders.

Intraventricularly injected Olig2-NSCs attenuate established relapsing-remitting EAE in mice.

In multiple sclerosis (MS), a chronic inflammatory relapsing demyelinating disease, failure to control or repair damage leads to progressive neurological dysfunction and neurodegeneration. Implantation of neural stem cells (NSCs) has been shown to promote repair and functional recovery in the acute experimental autoimmune encephalomyelitis (EAE) animal model for MS; the major therapeutic mechanism of these NSCs appeared to be immune regulation. In the present study, we examined the efficacy of intraventricularly injected NSCs in chronic relapsing experimental autoimmune encephalomyelitis (CREAE), the animal disease model that is widely accepted to mimic most closely recurrent inflammatory demyelination lesions as observed in relapsing-remitting MS. In addition, we assessed whether priming these NSCs to become oligodendrocyte precursor cells (OPCs) by transient overexpression of Olig2 would further promote functional recovery, for example, by contributing to actual remyelination. Upon injection at the onset of the acute phase or the relapse phase of CREAE, NSCs as well as Olig2-NSCs directly migrated toward active lesions in the spinal cord as visualized by in vivo bioluminescence and biofluorescence imaging, and once in the spinal cord, the majority of Olig2-NSCs, in contrast to NSCs, differentiated into OPCs. The survival of Olig2-NSCs was significantly higher than that of injected control NSCs, which remained undifferentiated. Nevertheless, both Olig2-NSCs and NSC significantly reduced the clinical signs of acute and relapsing disease and, in case of Olig2-NSCs, even completely abrogated relapsing disease when administered early after onset of acute disease. We provide the first evidence that NSCs and in particular NSC-derived OPCs (Olig2-NSCs) ameliorate established chronic relapsing EAE in mice. Our experimental data in established neurological disease in mice indicate that such therapy may be effective in relapsing-remitting MS preventing chronic progressive disease.

Interactions between HLH and bHLH factors modulate light-regulated plant development.

Phytochromes (Phy) and phytochrome-interacting factor (PIF) transcription factors constitute a major signaling module that controls plant development in response to red and far-red light. A low red:far-red ratio is interpreted as shading by neighbor plants and induces cell elongation-a phenomenon called shade-avoidance syndrome (SAS). PAR1 and its closest homolog PAR2 are negative regulators of SAS; they belong to the HLH transcription factor family that lacks a typical basic domain required for DNA binding, and they are believed to regulate gene expressions through DNA binding transcription factors that are yet to be identified. Here, we show that light signal stabilizes PAR1 protein and PAR1 interacts with PIF4 and inhibits PIF4-mediated gene activation. DNA pull-down and chromatin immunoprecipitation (ChIP) assays showed that PAR1 inhibits PIF4 DNA binding in vitro and in vivo. Transgenic plants overexpressing PAR1 (PAR1OX) are insensitive to gibberellin (GA) or high temperature in hypocotyl elongation, similarly to the pifq mutant. In addition to PIF4, PAR1 also interacts with PRE1, a HLH transcription factor activated by brassinosteroid (BR) and GA. Overexpression of PRE1 largely suppressed the dwarf phenotype of PAR1OX. These results indicate that PAR1-PRE1 and PAR1-PIF4 heterodimers form a complex HLH/bHLH network regulating cell elongation and plant development in response to light and hormones.

Silencing of miR20a is crucial for Ngn1-mediated neuroprotection in injured spinal cord.

MicroRNAs (miRNAs) compose a relatively new discipline in biomedical research, and many physiological processes in disease have been associated with changes in miRNA expression. Several studies report that miRNAs participate in biological processes such as the control of secondary injury in several disease models. Recently, we identified novel miRNAs that were abnormally up-regulated in a traumatic spinal cord injury (SCI). In the current study, we focused on miR20a, which causes continuing motor neuron degeneration when overexpressed in SCI lesions. Blocking miR20a in SCI animals led to neural cell survival and eventual neurogenesis with rescued expression of the key target gene, neurogenin 1 (Ngn1). Infusion of siNgn1 resulted in functional deficit in the hindlimbs caused by aggressive secondary injury and actively enhanced the inflammation involved in secondary injury progression. The events involving miR20a underlie motor neuron and myelin destruction and pathophysiology and ultimately block regeneration in injured spinal cords. Inhibition of miR20a expression effectively induced definitive motor neuron survival and neurogenesis, and SCI animals showed improved functional deficit. In this study, we showed that abnormal expression of miR20a induces secondary injury, which suggests that miR20a could be a potential target for therapeutic intervention following SCI.

Hydrodynamics-based transfection of the combination of betacellulin and neurogenic differentiation 1 DNA ameliorates hyperglycemia in mice with streptozotocin-induced diabetes.

BACKGROUND: The biohazards caused by the viral delivery of pancreatic transcription factors, including neurogenic differentiation 1 (Neurod1) and Betacellulin (Btc), to the murine liver limit application of this procedure in reversing diabetes. We aimed to evaluate the feasibility of hydrodynamics-based transfection (HBT) with Neurod1 and Btc in improving hyperglycemia. METHODS: Murine hepatocellular carcinoma (Hepa1-6) cells were transfected with the combination of Neurod1-expressing plasmid, pcDNA3.1/V5-His A (pcDNA)-Neurod1, and Btc-expressing plasmid, pcDNA3.1/V5-His A (pcDNA)-Btc. Hepatic delivery of a combination of pcDNA-Neurod1 and pcDNA-Btc (experimental group) or pcDNA (control group) to mice with streptozocin-induced diabetes was achieved by HBT. The sequential serum glucose and alanine aminotransferase (ALT) levels were assessed. RESULTS: On day 3 after transfection, the transfection efficiencies of pcDNA-Btc and pcDNA-Neurod1 in the Hepa1-6 cells were 20% and 8%, respectively; respective values in the mouse livers were 30% and 10%. At 1 week after HBT, aside from hepatic expression of insulin, the experimental mice had a significantly lower sugar level (8-14 days after HBT, P values ranged from 0.034 to <0.001) than the control mice; the difference remained for 1 week but diminished afterward. The ALT levels and the body weight change were not different between the two groups. No mortality was noted in both groups. CONCLUSIONS: The hypoglycemic effect of Neurod1 and Btc delivered by HBT was transient and associated with negligible complications. In studies on the short-term hypoglycemic effects of Neurod1 and Btc in vivo, HBT is a potential alternative to viral delivery of Neurod1 and Btc to the murine liver.