Résumé
AIM:To observe the neuritogenic actions of botulinum neurotoxin serotype A heavy chain ( BoNT/A HC) on cultured Neuro-2a cells and to investigate the related signaling mechanisms for the effect of BoNT /A HC. METHODS:Neuro-2a cells were treated with different doses of BoNT/A HC (0.01, 0.1, 1 and 10 nmol/L), and then the cells were harvested at 24 h, 48 h and 72 h of BoNT/A HC exposure for detecting the neurite length and the percen-tage of the cells with neuronal processes by immunofluorescence staining .The most efficient dose of BoNT/A HC was cho-sen for exposure to Neuro-2a cells as the above.Whole cell protein was harvested at different time points for detecting the protein levels of phosphorylated ERK 1/2 ( p-ERK1/2 ) and phosphorylated Akt ( p-Akt ) by Western blot .RESULTS:Low doses of BoNT/A HC stimulated the neurite outgrowth , and increased the percentage of the cells with neurites com-pared with the negative controls (P<0.05), especially in the group with 1 nmol/L of BoNT/A HC treatment.Meanwhile, the phosphorylation of ERK 1/2 and Akt was increased after treated with BoNT/A HC.There was an increasing tendency for the phosphorylation of ERK1/2 after the exposure of the cells to BoNT/A HC.The obvious increase in p-ERK1/2 was seen from 60 min to 5 h with 1 nmol/L of BoNT/A HC treatment ( P<0.05 ) , and the increased protein level of p-Akt was mainly observed at 15 min and 60 min ( P<0.05 ) .CONCLUSION: BoNT/A HC stimulates the neuritogenesis .The neuritogenic mechanism of BoNT/A HC on Neuro-2a cells might be realized by activation of the phosphorylation of ERK 1/2 and Akt.
Résumé
Calotropis procera (Ait.) R. Br (Asclepiadaceae) is a species widely used in traditional medicine for the treatment of various diseases such as sickle cell disease, asthma and cancer. In Burkina Faso, it enter in the composition of FACA® in combination with Zanthoxylum zanthoxyloides Lam (Rutaceae), drug used in sickle cell disease treatment. The objective of this study was to evaluate the in vitro cytotoxicity of aqueous extract of root barks of the plant on cell lines to increase the safe use of FACA®. MTT and Neutral Red assays performed on Caco-2 and Neuro-2a cell lines revealed that aqueous extract from root barks of Calotropis procera are cytotoxic on these cell lines. DNA fragmentation assay on Caco-2 cell showed DNA smearing reflecting a degradation of nuclear material that indicates a possible genotoxicity. Altogether, it comes out that the most sensitive cell line is the human colorectal carcinoma Caco-2 cells. Comparatively the active compounds of Calotropis procera do not affect the mice nervous system cells in the same dramatic extent. Our results strongly suggest that patients under treatment of FACA® must respect doses prescribed in order to avoid adverse side effects on the gastrointestinal tract.
Résumé
Objective To construct the lamino acid transporter 1 eukaryotic expression vector of C 57 mouse and to express the gene inNeuro-2atumor cells,and explore the effect of LAT1on proliferation and apoptosis of Neuro-2a cell. Methods The full-length LAT1 cDNA was synthesized by RT-PCR and cloned into pcDNA3.1vector to construct recombinant plasmid.The constructed pcDNA3.1-LAT1vector was verified by Enzyme digestion and sequencing and then transfected intomurine Neuro-2acellsby liposome.The transfected cells were selected with G418 and stably expressed strain was constructed .The expression of LAT1 was detected by RT-PCR and western blot .Proliferation was analyzed by MTT , cell cycle and apoptosis were detected by flow cytometric analysis .Results The full-length LAT1 cDNA was amplified successfully and pcDNA3.1-LAT1eukaryoticvector was constructed successfully .Enzyme digestion and sequencing confirmed the sequence was correct .Neuro-2acells were transfected and Stably expressed strain was constructed successfully.MTT showed that the group of transfected restructuring plasmid could significantly affect Neuro -2a cell proliferation more than the control groups ( P <0.05 ) .From the flowcytometric analysis , LAT1 could promote cell proliferation and inhibit Neuro-2a cell apoptosis.Conclusion LAT1 can express successfully inNeuro-2acells which were transfected with recombinantpcDNA3.1-LAT1plasmid.LAT1 in Neuro-2a cells can promote cell proliferation and inhibit the cell apoptosis which provides a basis for the study of LAT 1.That lays the foundation for studying biological effects of LAT 1.