Frank-Kamenetsky Maria, Zhang Xiaoyan M, Bottega Steve, Guicherit Oivin, Wichterle Hynek, Dudek Henryk, Bumcrot David, Wang Frank Y, Jones Simon, Shulok Janine, Rubin Lee L, Porter Jeffery A
Curis, Inc., 61 Moulton Street, Cambridge, MA 02138, USA.
J Biol. 2002 Nov 6;1(2):10. doi: 10.1186/1475-4924-1-10.
The Hedgehog (Hh) signaling pathway is vital to animal development as it mediates the differentiation of multiple cell types during embryogenesis. In adults, Hh signaling can be activated to facilitate tissue maintenance and repair. Moreover, stimulation of the Hh pathway has shown therapeutic efficacy in models of neuropathy. The underlying mechanisms of Hh signal transduction remain obscure, however: little is known about the communication between the pathway suppressor Patched (Ptc), a multipass transmembrane protein that directly binds Hh, and the pathway activator Smoothened (Smo), a protein that is related to G-protein-coupled receptors and is capable of constitutive activation in the absence of Ptc.
We have identified and characterized a synthetic non-peptidyl small molecule, Hh-Ag, that acts as an agonist of the Hh pathway. This Hh agonist promotes cell-type-specific proliferation and concentration-dependent differentiation in vitro, while in utero it rescues aspects of the Hh-signaling defect in Sonic hedgehog-null, but not Smo-null, mouse embryos. Biochemical studies with Hh-Ag, the Hh-signaling antagonist cyclopamine, and a novel Hh-signaling inhibitor Cur61414, reveal that the action of all these compounds is independent of Hh-protein ligand and of the Hh receptor Ptc, as each binds directly to Smo.
Smo can have its activity modulated directly by synthetic small molecules. These studies raise the possibility that Hh signaling may be regulated by endogenous small molecules in vivo and provide potent compounds with which to test the therapeutic value of activating the Hh-signaling pathway in the treatment of traumatic and chronic degenerative conditions.
刺猬信号通路（Hh）对动物发育至关重要，因为它在胚胎发生过程中介导多种细胞类型的分化。在成体中，Hh信号可被激活以促进组织维持和修复。此外，刺激Hh通路已在神经病变模型中显示出治疗效果。然而，Hh信号转导的潜在机制仍不清楚：关于该通路的抑制因子Patched（Ptc）（一种直接结合Hh的多次跨膜蛋白）与通路激活因子Smoothened（Smo）（一种与G蛋白偶联受体相关且在没有Ptc时能够组成性激活的蛋白）之间的通讯了解甚少。
我们鉴定并表征了一种合成的非肽类小分子Hh-Ag，它作为Hh通路的激动剂。这种Hh激动剂在体外促进细胞类型特异性增殖和浓度依赖性分化，而在子宫内它可挽救音猬因子缺失但Smo不缺失的小鼠胚胎中Hh信号缺陷的某些方面。用Hh-Ag、Hh信号拮抗剂环杷明和一种新型Hh信号抑制剂Cur61414进行的生化研究表明，所有这些化合物的作用均独立于Hh蛋白配体和Hh受体Ptc，因为它们各自直接结合Smo。
Smo的活性可直接被合成小分子调节。这些研究提出了Hh信号可能在体内受内源性小分子调节的可能性，并提供了有效的化合物来测试激活Hh信号通路在治疗创伤性和慢性退行性疾病中的治疗价值。
