HspB5 protects mouse neural stem/progenitor cells from paraquat toxicity.

INTRODUCTION: HspB5 (αB-crystallin) is known to be involved in a variety of cellular functions, including, protection of cells from oxidative damage and inhibiting apoptosis. Neural stem/progenitor cells (NSPCs) have significant therapeutic value, especially in the NSC/NPC transplantation therapy. However, the viability of the transplanted NSPCs remains low because of various factors, including oxidative stress.

OBJECTIVE: The current investigation explored the possible role of HspB5 in the protection of mouse NSPCs ( m NSPCs) against paraquat-induced toxicity.

METHODS: The recombinant human HspB5 was expressed in E.coli and was purified using gel filtration and Ion-exchange chromatography. The biophysical characterization of HspB5 was carried out using DLS, CD, and Analytical Ultracentrifugation (SV); the chaperone activity of HspB5 was determined by alcohol dehydrogenase aggregation assay. We have subjected the mNSPCs to paraquat-induced oxidative stress and monitored the protective ability of HspB5 by MTT assay and Hoechst-PI staining. Furthermore, increase in the expression of the anti-apoptotic protein, procaspase-3 was monitored using western blotting.

RESULTS: The recombinant HspB5 was purified to its homogeneity and was characterized using various biophysical techniques. The externally added FITC-labeled HspB5 was found to be localized within the cytoplasm of m NSPCs. Our Immunocytochemistry results showed that the externally added FITC-labeled HspB5 not only entered the cells but also conferred cytoprotection against paraquat-induced toxicity. The protective events were monitored by a decrease in the PI-positive cells and an increase in the procaspase-3 expression through Immunocytochemistry and Western blotting respectively.

CONCLUSION: Our results clearly demonstrate that exogenously added recombinant human HspB5 enters the m NSPCs and confers protection against paraquat toxicity.