α-突触核蛋白A30P突变对小鼠海马齿状回神经发生的影响

Eeffects of A30Pα-synuclein mutation on dentate gyrus neurogenesis in mouse hippocampus

α-突触核蛋白(α-synuclein,SNCA)A30P点突变是帕金森病(Parkinson disease,PD)的主要标志之一。已知PD的发生发展与大脑海马齿状回(dentate gyrus,DG)的神经紊乱有密切关系,但尚不清楚该突变对成体DG神经发生有何直接影响。本研究以C57BL/6正常小鼠(C57BL)、内源性SNCA敲除鼠(SNCA-/-)、SNCA-/-+人SNCA A30P突变基因敲入鼠(A30P SNCA-/-)为实验动物(每组4只),经灌流固定、冰冻切片和免疫荧光组织化学染色,观察分析其DG形态学变化及磷酸化组蛋白3(PH3,增殖标记)、双皮质素(Dcx,神经母细胞标记)、Sox2(干细胞标记)阳性细胞数。结果显示,各组小鼠DG的形态、大小及细胞密度等无明显差异;与C57BL小鼠相比,SNCA-/-和A30P SNCA-/-组小鼠DG中PH3+和Dcx+细胞数量显著减少,而Sox2+细胞数无明显差异。以上结果表明,内源性SNCA的正常表达是DG神经发生所必需的,SNCA-/-和A30P SNCA-/-均能显著减弱或抑制小鼠DG细胞增殖、分化等神经发生活动,但有关其详细分子机制仍需后续进一步研究。

Alpha-synuclein(SNCA)A30 P point mutation is one of the main hallmarks of Parkinson disease(PD).It is known that the occurrence and development of PD are closely related to the disorder of the dentate gyrus(DG)neurogenesis in adult hippocampus.However,it is still unclear what is the direct influence of SNCA A30 P mutation on the DG neurogenesis.In this study,normal C57 BL/6(C57 BL)mice,endogenous SNCA gene knockout(SNCA-/-)mice and SNCA-/-+human SNCA A30 P knockin(A30 P SNCA-/-)mice were used as the experimental animals(n=4 in each type).Mouse brains were carefully dissected and the coronal frozen sections of the hippocampus were created after perfusion fixation.The DG morphology and the positive cells of phosphohistone 3(PH3,proliferation marker),doublecortin(Dcx,neuroblast marker)and Sox2(stem cell marker)were observed and analyzed.The results showed that no gross difference was observed for the morphology,size as well as the cell densities in the DG among three groups.Compared with C57 BL/6 mice,PH3+cells and Dcx+cells in SNCA-/-and A30 P SNCA-/-mice decreased significantly,while no statistical differences of Sox2+cell numbers was observed.These results suggested that the normal expression of endogenous SNCA is necessary for the DG neurogenesis,both SNCA-/-and A30 P SNCA-/-can decrease or inhibit the neurogenic activities such as the proliferation and differentiation in the DG of mouse hippocampus.However,the detailed molecular mechanisms behind this still needs to be further explored in next step.