丝氨酸羟甲基转移酶2在小鼠肝再生过程中的变化规律及作用

目的 探索丝氨酸羟甲基转移酶2(serine hydroxymethyl transferase 2,SHMT2)在小鼠肝再生过程中的表达规律,以及其对小鼠肝再生是否有促进作用.方法 SPF级C57BL/6小鼠120只分为肝切除组(2/3 PH)、假手术组(SHAM)、腺病毒干扰组(siSHMT2)及注射生理盐水对照组(Control),每组30只;肝切除组下设1、3、5、7、9d5个时相点,每个时相点6只.小鼠肝切除之后分别取1、3、5、7、9d的肝脏组织及血清,采用qPCR、Western blot和免疫组化检测SHMT2及其下游分子甘氨酸脱氢酶(glycine dehydrogenase,GLDC)的变化规律、血清中丙氨酸转氨酶(alanine transaminase,ALT)和谷草转氨酶(aspartate transaminase,AST)的浓度.取注射腺病毒干扰SHMT2第5天的肝脏组织,通过Westernblot和观察荧光强度,确定转染效果,并检测血浆中ALT和AST水平,免疫组化检测增殖细胞核抗原(proliferating cell nuclear antigen,PCNA).结果 SHMT2及其下游分子GLDC在小鼠肝再生的后第5、7天表达最高,qPCR检测结果显示,SHMT2第5天的表达量是第1天的1.63倍(P＜0.05).在干扰SHMT2之后,小鼠第5天再生肝脏的质量由(0.79±0.13)g降低至(0.63 ±0.ll)g(P ＜0.05),再生度由(36.37±2.21)％降低至(31.33±1.92)％,肝指数由(3.76±0.44)％降低至(3.13±0.29)％,并且肝功能指标ALT由(70.00±9.52) U/L升高至(154.15±16.49) U/L,AST由(140.09±32.85) U/L升高至(403.41±68.63) U/L(P＜0.05),PCNA阳性率从(53.6±2.3)％降低至(39.0±3.2)％(P＜0.05).结论 SHMT2在肝脏再生的后期高表达,促进残肝的再生,其机制可能与增强肝脏对缺血、缺氧的耐受,提高三磷酸腺苷水平有关.

Expression profile and function of serine hydroxymethyl transferase 2 during liver regeneration in mice

Objective To determine the expression profile of serine hydroxymethyl transferase 2 (SHMT2) during mouse liver regeneration and investigate whether it exerts promoting effect in the process.Methods A total of 120 SPF C57BL/6 mice were randomly assigned to 2/3 partial hepatectomy (2/3PH),sham operation,siSHMT2 and control groups (normal saline).The liver tissue and serum samples were collected at 1,3,5,7 and 9 d after the surgery with 6 mice in each time point.The expression profiles of SHMT2 and its downstream molecule glycine dehydrogenase (GLDC),and the serum levels of alanine transaminase (ALT) and aspartate transaminase (AST) were detected by qPCR,Western blotting and immunohistochemical assay respectively.The effect of siSHMT2 was determined by observing fluorescent signals,detecting the expression of SHMT2 and proliferating cell nuclear antigen (PCNA) and serum levels of ALT and AST.Results The expression levels of SHMT2 and GLDC reached highest in 5 and 7 d after operation,with the mRNA amount of SHMT2 increased by 1.63 times at day 5 than day 1 (P ＜ 0.05).When compared with the 2/3PH group,SHMT2 interference resulted in the lower liver weight at 5 d (0.63 ±0.11 vs 0.79 ±0.13 g,P ＜0.05),lower liver regeneration [(31.33 ± 1.92)％ vs (36.37 ±2.21) ％] and liver index [(3.13 ± 0.29) ％ vs (3.76 ± 0.44) ％],and decreased positive rate of PCNA [(39.0 ± 3.2) ％ vs (53.6 ± 2.3) ％,P ＜ O.05],while increased serum levels of AST (403.41 ± 68.63 vs 140.09 ± 32.85 U/L,P＜0.05) and ALT (154.15 ±16.49 vs 70.00 ±9.52 U/L,P＜0.05).Conclusion SHMT2 is highly expressed in the late stage of liver regeneration,and promotes liver regeneration,which might be through its enhancing liver tolerance to ischemia and hypoxia and promoting adenosine triphosphate level.