The roles of Ptch1 and Disp1 in the formation of the Shh gradient

描述(申请人提供)：Sonic Hedgehog(Shh)是一种信号分子，经过翻译后修饰，导致蛋白质增加两个亲脂部分，使其与强制性膜相关。尽管有这些修改，但在发育过程中，在干细胞的缝隙中，在肿瘤中，Shh向细胞发出信号，通常距离合成地点几个细胞直径。Shh的分泌和邻近细胞对Shh的摄取分别需要Disp1和Ptc1两个相关分子。假设Shh的运输涉及Disp1和Ptc1的重复和互补作用，产生和吸收含有Shh的复合体(脂蛋白颗粒或外切体)，从而在产生Shh活性梯度的同时介导长距离运输。三个中心观察支持这一假说，没有Disp1的I/细胞不分泌Shh，II/ptch1需要周围细胞摄取Shh，而III/没有Disp1的组织运输Shh的能力较差。Ptch1和Disp1是质子驱动的三聚体逆向转运蛋白大家族的成员，第一个目的是测试Shh的平面转胞是否需要ptch1和Disp1功能。在目标2中，讨论了运输的根尖基极以及反应，以使基侧运输与初级纤毛的顶端定位相协调。目标3和4涉及Shh的行程，以及假定的质子驱动的ptch1和Disp1泵活动在Shh的运输中的作用，以及相关的Smoothed的重新定位。

DESCRIPTION (provided by applicant): Sonic Hedgehog (Shh) is a signaling molecule that undergoes post-translational modifications resulting in the addition two lipophilic moieties to the protein, rendering it obligatory membrane associated. Despite these modifications, during development, in stem cell niches, and in tumors Shh signals to cells often several cell diameters away from the sites of synthesis. Two related molecules, Disp1 and Ptc1, are required for the secretion of Shh and its uptake in neighboring cells respectively. It is hypothesized that transport of Shh involves the reiterated and complementary actions of Disp1 and Ptc1 generating and absorbing Shh containing complexes (either lipoprotein particles or exosomes) thus mediating long-range transport while generating a Shh activity gradient. Three central observations support this hypothesis, i/ cells without Disp1 do not secrete Shh, ii/ Ptch1 in surrounding cells is required for the uptake of Shh and iii/ tissues without Disp1 are less able to transport Shh. Ptch1 and Disp1 are members of a large family of trimeric, proton driven antiporters, and in the first aim it is tested if Ptch1 and Disp1 function is required for planar transcytosis of Shh. In aim 2 the apicobasal polarity of the transport as well as the response is addressed, to reconcile basolateral transport with the apical localization of the primary cilium. Aims 3 and 4 address the Shh itinerary as well as the role of the putative proton driven pump activity of Ptch1 and Disp1 in the transport of Shh, and the associated relocation of Smoothened.