Cozza Giorgio, Zanin Sofia, Determann Renate, Ruzzene Maria, Kunick Conrad, Pinna Lorenzo A
Department of Biomedical Sciences, University of Padova, and CNR Institute of Neurosciences, Padova, Italy.
Technische Universität Braunschweig, Institut für Medizinische und Pharmazeutische Chemie, Braunschweig, Germany.
PLoS One. 2014 Feb 24;9(2):e89176. doi: 10.1371/journal.pone.0089176. eCollection 2014.
Homeodomain-interacting protein kinase 2 (HIPK2) is a Ser/Thr kinase controlling cell proliferation and survival, whose investigation has been hampered by the lack of specific inhibitors able to dissect its cellular functions. SB203580, a p38 MAP kinase inhibitor, has been used as a tool to inhibit HIPK2 in cells, but here we show that its efficacy as HIPK2 inhibitor is negligible (IC₅₀>40 µM). In contrast by altering the scaffold of the promiscuous CK2 inhibitor TBI a new class of HIPK2 inhibitors has been generated. One of these, TBID, displays toward HIPK2 unprecedented efficacy (IC₅₀ = 0.33 µM) and selectivity (Gini coefficient 0.592 out of a panel of 76 kinases). The two other members of the HIPK family, HIPK1 and HIPK3, are also inhibited by TBID albeit less efficiently than HIPK2. The mode of action of TBID is competitive with respect to ATP, consistent with modelling. We also provide evidence that TBID is cell permeable by showing that HIPK2 activity is reduced in cells treated with TBID, although with an IC₅₀ two orders of magnitude higher (about 50 µM) than in vitro.
同源结构域相互作用蛋白激酶2（HIPK2）是一种控制细胞增殖和存活的丝氨酸/苏氨酸激酶，对其研究因缺乏能够剖析其细胞功能的特异性抑制剂而受到阻碍。SB203580是一种p38丝裂原活化蛋白激酶抑制剂，已被用作在细胞中抑制HIPK2的工具，但我们在此表明，其作为HIPK2抑制剂的效力可忽略不计（IC₅₀>40 μM）。相比之下，通过改变混杂性蛋白激酶2抑制剂TBI的支架结构，已产生了一类新的HIPK2抑制剂。其中一种，即TBID，对HIPK2显示出前所未有的效力（IC₅₀ = 0.33 μM）和选择性（在一组76种激酶中吉尼系数为0.592）。HIPK家族的另外两个成员，HIPK1和HIPK3，也受到TBID的抑制，尽管效率低于HIPK2。TBID的作用方式在ATP方面具有竞争性，与模型一致。我们还通过表明在用TBID处理的细胞中HIPK2活性降低，提供了TBID可透过细胞的证据，尽管其IC₅₀比体外高两个数量级（约50 μM）。
