Affect of Socs2 loss-of-function on liver regeneration

SOCS2 Ensures Metabolic Function and Mass Restoration During Liver Regeneration - SOCS2 plays distinct and contrasting roles during liver regeneration. Early after injury, SOCS2 expression increases and limits the rate of regeneration, preserving metabolic activity. Surprisingly, at later times, the role of SOCS2 reverses to promote liver regeneration by stimulating GH release from the pituitary via effects on serum levels of insulin-like growth factor 1. Loss of SOCS2 promotes GH signaling by increasing growth hormone receptor levels and driving phosphorylation of proteins in the GH pathway, establishing a state of hyper-responsiveness to GH. These findings suggest a single protein can play contrasting roles at different times after liver injury and modulation of GH signaling achieves an optimal rate of liver regeneration to balance metabolic and restorative needs. To further understand the mechanism by which SOCS2 increases early liver regeneration, we performed microarray analysis of Socs2-null mice wildtype mice at 24 and 36 hours after hepatectomy. C57BL/6 mice where used as wildtype controls. Socs2-null animals were maintained on a C57BL/6 background. Both wildtype and Socs2-null adult mice were subjected to 2/3 hepatectomy and liver tissue isolated at 24 hours and 36 hours post hepatectomy. Time zero was without hepatectomy in age-matched mice for each genotype. Total RNA isolated from collected liver tissues was pooled for three animals at each time point and two biological replicates (3 pooled liver RNAs each) were labeled for array analysis. This results in a total of 12 microarrays.

细胞因子信号抑制因子2（SOCS2）在肝脏再生过程中保障代谢功能与肝质量恢复——SOCS2在肝脏再生过程中发挥着截然不同且相互对立的作用。损伤早期，SOCS2的表达水平上调，可抑制肝脏再生速率，同时维持代谢活性。令人意外的是，在损伤后期，SOCS2的作用发生逆转：它可通过影响血清胰岛素样生长因子1（insulin-like growth factor 1, IGF-1）水平，促进垂体释放生长激素（Growth Hormone, GH），进而推动肝脏再生。SOCS2缺失会通过上调生长激素受体水平、激活生长激素通路中蛋白质的磷酸化，增强生长激素信号转导，使机体对生长激素产生高反应性状态。上述研究结果表明，单一蛋白质可在肝损伤后的不同阶段发挥对立的作用，而通过调控生长激素信号转导，可实现肝脏再生的最优速率，以平衡代谢与组织修复的需求。为进一步阐明SOCS2促进早期肝脏再生的分子机制，我们对肝切除术后24小时及36小时的Socs2基因敲除（Socs2-null）小鼠与野生型小鼠开展了基因芯片（microarray）分析。实验以C57BL/6小鼠作为野生型对照，Socs2基因敲除小鼠均为C57BL/6遗传背景。将成年野生型与Socs2基因敲除小鼠实施2/3肝切除术（hepatectomy），并分别于术后24小时、36小时采集肝组织样本。针对每个基因型，均设置同龄且未实施肝切除术的小鼠作为0小时对照组。从收集的肝组织中提取总RNA，每个时间点取3只小鼠的总RNA进行混合，共设置2组生物学重复（每组重复包含3份混合后的肝组织总RNA），随后对所有样本进行标记以用于基因芯片分析。本实验共计完成12张基因芯片的检测。