Prokaryotic expression, purification of human LINGO-1(aa76-319) and preparation of its polyclonal antibody / 南方医科大学学报

<p><b>OBJECTIVE</b>To express and purify the fusion protein of extracellular domain of human Ig domain-containing, neurite outgrowth inhibitor (Nogo) receptor-interacting protein-1 (LINGO-1(aa76-319)) in prokaryotic cells and prepare the rabbit anti-LINGO-1 polyclonal antibody (pAb).</p><p><b>METHODS</b>The 732 bp DNA sequence of hLINGO-1(aa76-319) was obtained from pCMV-SPORT6 by PCR and inserted into pET30a(+) plasmid to construct the prokaryotic expression plasmid pET30a(+)-hLINGO-1(aa76-319), which was subsequently transformed into E.coli. The target fusion protein was expressed with IPTG induction and purified by Ni(2+)-NTA affinity chromatography column. The antiserum against hLINGO-1(aa76-319) was obtained from the rabbits immunized with hLINGO-1(aa76-319), and the titer of the pAb was determined using enzyme linked immunosorbent assay (ELISA) and its specificity identified using Western blotting.</p><p><b>RESULTS</b>The prokaryotic expression plasmid pET30a(+)-hLINGO-1(aa76-319) was constructed successfully. Efficient expression of the target fusion protein was achieved with IPTG induction at the optimal concentration of 0.4 mmol/L and culture temperature at 37 degrees celsius; for 2.5 h. The hLINGO-1(aa76-319) fusion protein was effectively expressed in E.coli as inclusion bodies, and the soluble protein was obtained through denaturation and refolding procedures, and the purified fusion protein showed a purity above 90%. The titer of the anti-hLINGO-1(aa76-319) pAb obtained by immunizing the rabbits with the purified protein reached 1:1.6x10(6), and Western blotting confirmed its good specificity.</p><p><b>CONCLUSION</b>The fusion protein hLINGO-1(aa76-319) with high purity has been obtained and the anti-hLINGO-1(aa76-319) pAb obtained shows a high titer and good specificity, which provide important experimental basis for further functional investigation of LINGO-1.</p>

Effect of superparamagnetic iron oxide labeling on neural stem cell survival and proliferation / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effect of superparamgnetic iron oxides (ferumoxides) on the survival and proliferation of neural stem cells (NSCs) and determine the optimal ferumoxides concentration for labeling.</p><p><b>METHODS</b>Bone marrow stromal cells (BMSCs) were obtained from rat femoral marrow and cultured in vitro to induce their differentiation into NSCs. Ferumoxides labeling of the NSCs was performed with different final concentrations of ferumoxides, and the labeling efficiency and viability of the labeled NSCs were evaluated by Prussian blue staining, MTT assay, flow cytometry and transmission electron microscope.</p><p><b>RESULTS</b>The NSCs could be effectively labeled with ferumoxides with a labeling efficiency of around 90%. Prussian blue staining showed numerous fine granules with blue staining in the cytoplasm of the labeled NSCs, and the intensity of the blue staining was in positive correlation with the ferumoxide concentration for labeling. Transmission electron microscopy of the labeled NSCs revealed the presence of numerous vesicles spreading in the cytoplasm and filled with electron-dense magnetic iron particles. The ferumoxides vesicles increased with the labeling concentration of ferumoxides, and at the final concentration exceeding 25 microg/ml, ferumoxides vesicles in the NSCs gave rise to conglomeration which hampered observation of the cellular ultrastructure by transmission electron microscope. The results of flow cytometry and MTT assay demonstrated that the cell viability, proliferation, differentiation and apoptosis of the labeled cells were affected by ferumoxides at the concentration above 25 microg/ml, but such effects could be minimal at lower concentrations.</p><p><b>CONCLUSION</b>Ferumoxides might be feasible for in vitro labeling of the NSCs with the optimal concentration of 25 microg/ml.</p>

Effect of N-acetyl-cysteine and depakine pretreatment on ferrous chloride-induced membrane potential and peroxidate changes in rat cortex neurons / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of N-acetyl-cysteine (NAC) and depakine (DP) on the changes of membrane potential and peroxidate in rat cortex neurons exposed to ferrous chloride (FeCl(2)).</p><p><b>METHODS</b>Cultured cortex neurons of newly born SD rats were randomly divided into control group (PBS group), model group (FeCl(2) group), NAC pretreatment group (NAC group), DP pretreatment group (DP group) and NAC+DP pretreatment group (NAC+DP group). In the latter three groups, NAC (0.08 mg/ml) and DP (0.1 mg/ml) were added in the cell culture 2 and 3 h before FeCl(2) (1 mmol/L) exposure, respectively. After exposure to FeCl(2), the membrane potential of the neurons was detected with fluorescent dye DiBAC4(3) (bis-(1,3-dibutylbarbituric acid) trimethine oxonol), and the peroxidate level with 2,7-dichlorofluorescin diacetate (H(2)DCF) by laser confocal scanning microscope (LCSM) and nuclear factor-KappaB (NF-KappaB) level with immunocytochemistry.</p><p><b>RESULTS</b>Compared with FeCl(2) group, the expression of NF-KappaB and peroxidate level in the neurons were decreased significantly in NAC and NAC+DP groups (P<0.01), but not in DP group (P>0.05). FeCl(2) depolarized the membrane potential and increased the expression of NF-KappaB in the neurons. Compared with FeCl(2) group, significant changes in the membrane potential were observed in DP and NAC+DP groups (P<0.01) but not in NAC or PBS group (P>0.05).</p><p><b>CONCLUSION</b>Both NAC and DP can protect the neurons from FeCl(2)-induced damage but through different pathways, and their combined use can significantly alleviate neuronal damages due to FeCl(2) exposure. Antioxidants such as NAC in combination with antiepileptic drugs may produce favorable effect in prevention and treatment of posttraumatic epilepsy.</p>