人和大鼠膀胱平滑肌细胞存在低水平的自噬

Autophagy at low level in human and rat bladder smooth muscle cells

目的探讨人和大鼠膀胱平滑肌细胞是否存在自噬，以阐明自噬在膀胱疾病中的作用。方法 雌性SD大鼠8只，2～3月龄，体质量200～230 g。人膀胱标本（n=4）来自于西南医院泌尿外科膀胱癌全切患者。HE染色观察膀胱肌层定位。透射电镜（TEM）用于人和大鼠膀胱平滑肌细胞自噬小体鉴定。免疫荧光双标用于人和大鼠微管相关蛋白1轻链3（LC3）和平滑肌肌动蛋白（α-SMA）共定位。Western blot和RT-PCR检测人和大鼠膀胱肌层组织LC3蛋白和mRNA表达。结果 TEM证实人和大鼠膀胱平滑肌细胞存在自噬小体。免疫荧光双标和Western blot证实人和大鼠膀胱平滑肌细胞存在自噬标记蛋白LC3的表达。RT-PCR证实人和大鼠膀胱平滑肌细胞存在自噬标记蛋白LC3 mRNA的表达。结论 人和大鼠膀胱平滑肌细胞存在自噬，这种低水平自噬可能在维持膀胱平滑肌细胞自身稳态中起到重要作用。

Objective To investigate whether there exists autophagy in the human and rat bladder smooth muscle cells in order to elucidate the role of autophagy in bladder diseases. Methods A total of 8 male SD rats at an age of 2 to 3 months, weighing 200 to 230 g were sacrificed for bladder tissue. Four samples of human bladder tissues were harvested from 4 patients of bladder cancer after radical cystectomy. HE staining was used to locate the bladder muscle layer. Transmission electron microscopy （TEM） was used for identification of autophagosome in the human and rat bladder smooth muscle cells. Co-location of human and rat microtubule-associated protein 1 light chain 3 （LC3） and α-smooth muscle actin （α-SMA） was detected with double-labeled immunofluorescent assay. The expression of LC3 at protein and mRNA levels was detected in human and rat bladder muscle layer by Western blotting and RT-PCR. Results TEM showed there existed autophagosomes in the human and rat bladder smooth muscle cells. Double-labeled immunofluorescent assay, Western blotting and RT-PCR confirmed the autophagy marker protein LC3 was expressed in the human and rat bladder smooth muscle cells. Conclusion The presence of autophagy in human and rat bladder smooth muscle cells at low level may play an important role in the maintenance of homeostasis in bladder smooth muscle cells.