A Tautomerase-Null Macrophage Migration-Inhibitory Factor (MIF) Gene Knock-In Mouse Model Reveals That Protein Interactions and Not Enzymatic Activity Mediate MIF-Dependent Growth Regulation
A Tautomerase-Null Macrophage Migration-Inhibitory Factor (MIF) Gene Knock-In Mouse Model Reveals That Protein Interactions and Not Enzymatic Activity Mediate MIF-Dependent Growth Regulation
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DOI：
10.1128/mcb.01907-08
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发表时间：
2009-04-01
影响因子：
5.3
通讯作者：
Bucala, Richard
中科院分区：
文献类型：
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作者：
Fingerle-Rowson, Guenter;Kaleswarapu, Dayananda Rao;Bucala, Richard
巨噬细胞移动抑制因子（MIF）是先天免疫的上游调节因子，也是炎症和癌症之间的潜在分子联系。MIF和某些互变异构酶之间的不寻常的结构同源性，包括保守的底物结合口袋和催化的N-末端脯氨酸（Pro 1），引发了对酶促反应是MIF生物学功能基础的猜测。为了解决MIF互变异构酶活性在体内的功能作用，我们建立了一个敲入小鼠，其中内源性mif基因被替换为编码互变异构酶无效的Pro 1-> Gly 1 MIF蛋白（P1 G-MIF）的基因。虽然P1 G-MIF完全无催化活性，但它与其细胞表面受体（CD 74）和细胞内结合蛋白JAB 1/CSN 5的结合保持显著的，尽管降低。P1 G-MIF敲入小鼠（mif（P1 G/P1 G））和源自这些小鼠的细胞在生长控制和肿瘤诱导的测定中显示介于野生型（mif（+/+））和完全MIF缺乏（mif（-/-））之间的表型。这些数据提供了遗传学证据表明，MIF的内在互变异构酶活性是该细胞因子的生长调节特性的基础，并支持N-末端区域在蛋白质-蛋白质相互作用中的作用。
Macrophage migration-inhibitory factor (MIF) is an upstream regulator of innate immunity and a potential molecular link between inflammation and cancer. The unusual structural homology between MIF and certain tautomerases, which includes both a conserved substrate-binding pocket and a catalytic N-terminal proline (Pro1), has fueled speculation that an enzymatic reaction underlies MIF's biologic function. To address the functional role of the MIF tautomerase activity in vivo, we created a knock-in mouse in which the endogenous mif gene was replaced by one encoding a tautomerase-null, Pro1 -> Gly1 MIF protein (P1G-MIF). While P1G-MIF is completely inactive catalytically, it maintains significant, albeit reduced, binding to its cell surface receptor (CD74) and to the intracellular binding protein JAB1/CSN5. P1G-MIF knock-in mice (mif(P1G/P1G)) and cells derived from these mice show a phenotype in assays of growth control and tumor induction that is intermediate between those of the wild type (mif(+/+)) and complete MIF deficiency (mif(-/-)). These data provide genetic evidence that MIF's intrinsic tautomerase activity is dispensable for this cytokine's growth-regulatory properties and support a role for the N-terminal region in protein-protein interactions.