The pathways by which mild hypothermia inhibits neuronal apoptosis following ischemia/reperfusion injury

Several studies have demonstrated that mild hypothermia exhibits a neuroprotective role and it can inhibit endothelial cell apoptosis following ischemia/reperfusion injury by decreasing casp- ase-3 expression, It is hypothesized that mild hypothermia exhibits neuroprotective effects on neurons exposed to ischemia/reperfusion condition produced by oxygen-glucose deprivation. Mild hypothermia significantly reduced the number of apoptotic neurons, decreased the expres- sion of pro-apoptotic protein Bax and increased mitochondrial membrane potential, with the peak of anti-apoptotic effect appearing between 6 and 12 hours after the injury. These findings indicate that mild hypothermia inhibits neuronal apoptosis following ischemia/reperfusion injury by protecting the mitochondria and that the effective time window is 6-12 hours after ischemia/reperfusion injury.

Differentiation of GDNF and NT-3 Dual Gene-modified Rat Bone Marrow Mesenchymal Stem Cells into Enteric Neuron-like Cells

Bone marrow mesenchymal stem cells (BMSCs) have been shown to be multipotent cells that possess high self-replicating capacity.The purpose of our study was to investigate the feasibility of using enteric neuron-like cells obtained by in vitro induction and differentiated from rat BMSCs for the treatment of Hirschsprung’s disease (HD).Glial cell-derived neurotrophic factor (GDNF) and neurotrophin-3 (NT-3) are neurotrophic factors that play important roles in neuronal development,differentiation,survival and function.Meanwhile,GDNF mutations are a major cause of HD.In this study,BMSCs were transfected with eukaryotic expression plasmids co-expressing GDNF and NT-3,and the trans-fected cells displayed neuron-like changes after differentiation induced by fetal gut culture medium (FGCM).Immunofluorescence assay showed positive expression of the neuronal marker NSE and the enteric neuronal markers PGP9.5,VIP and nNOS.Reverse transcription-polymerase chain reaction (RT-PCR) revealed the expression of GDNF and NT-3 in transfected BMSCs.The present study indicates that genetically modified BMSCs coexpressing GDNF and NT-3 are able to differentiate into en-teric neuronal cells and express enteric nerve markers when induced by FGCM.This study provides an experimental basis for gene therapy to treat enteric nervous system-related disorders,such as HD.

Plasma membrane calcium ATPase 4b inhibits nitric oxide generation through calcium-induced dynamic interaction with neuronal nitric oxide synthase

The activation and deactivation of Ca^(2+)- and calmodulindependent neuronal nitric oxide synthase (nNOS) in the central nervous system must be tightly controlled to prevent excessive nitric oxide (NO) generation. Considering plasma membrane calcium ATPase (PMCA) is a key deactivator of nNOS, the present investigation aims to determine the key events involved in nNOS deactivation of by PMCA in living cells to maintain its cellular context. Using time-resolved Förster resonance energy transfer (FRET), we determined the occurrence of Ca^(2+)-induced protein-protein interactions between plasma membrane calcium ATPase 4b (PMCA4b) and nNOS in living cells. PMCA activation significantly decreased the intracellular Ca 2+ concentrations ([Ca^(2+)]_(i)), which deactivates nNOS and slowdowns NO synthesis. Under the basal [Ca^(2+)]_(i) caused by PMCA activation, no protein-protein interactions were observed between PMCA4b and nNOS. Furthermore, both the PDZ domain of nNOS and the PDZ-binding motif of PMCA4b were essential for the protein-protein interaction. The involvement of lipid raft microdomains on the activity of PMCA4b and nNOS was also investigated. Unlike other PMCA isoforms, PMCA4 was relatively more concentrated in the raft fractions. Disruption of lipid rafts altered the intracellular localization of PMCA4b and affected the interaction between PMCA4b and nNOS, which suggest that the unique lipid raft distribution of PMCA4 may be responsible for its regulation of nNOS activity. In summary, lipid rafts may act as platforms for the PMCA4b regulation of nNOS activity and the transient tethering of nNOS to PMCA4b is responsible for rapid nNOS deactivation.

Induced pluripotency and direct reprogramming:a new window for treatment of neurodegenerative diseases

Human embryonic stem cells(hESCs)are pluripotent cells that have the ability of unlimited self-renewal and can be differentiated into different cell lineages,includ-ing neural stem(NS)cells.Diverse regulatory signaling pathways of neural stem cells differentiation have been discovered,and this will be of great benefit to uncover the mechanisms of neuronal differentiation in vivo and in vitro.However,the limitations of hESCs resource along with the religious and ethical concerns impede the pro-gress of ESCs application.Therefore,the induced pluri-potent stem cells(iPSCs)via somatic cell reprogramming have opened up another new territory for regenerative medicine.iPSCs now can be derived from a number of lin-eages of cells,and are able to differentiate into certain cell types,including neurons.Patient-specifi c iPSCs are being used in human neurodegenerative disease modeling and drug screening.Furthermore,with the development of somatic direct reprogramming or lineage reprogramming technique,a more effective approach for regenerative medicine could become a complement for iPSCs.