Context-dependent ciliary regulation of hedgehog pathway repression in tissue morphogenesis.
Context-dependent ciliary regulation of hedgehog pathway repression in tissue morphogenesis.
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DOI：
10.1371/journal.pgen.1011028
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发表时间：
2023-11
期刊：
影响因子：
4.5
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中科院分区：
文献类型：
--
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组织形态发生的一个基本问题是确定亚细胞信号如何调节组织的中尺度组织。初级纤毛是亚细胞内信号传递的典型细胞器。纤毛发出的信号如何协调组织结构--特别是纤毛产生的效应器在调节不同的形态表型结果中的作用--还没有被很好地理解。在Hedgehog途径中，双功能GLI转录因子同时产生GLI激活因子(GLI-A)和GLI抑制因子(GLI-R)。Gli-A/Gli-R的形成需要纤毛。然而，这些反调节效应器如何协调纤毛调节的形态发生途径尚不清楚。在这里，我们确定了由于在小鼠神经管和骨骼发育过程中缺乏Hedgehog途径抑制(去抑制)而产生的表型中GLI-A/GLI-R的需求。我们研究了GPCRGPR161和Ankyrin Repeat蛋白ANKMY2对Hedgehog通路的抑制作用，AnkMY2在GLI-R世代中通过纤毛引导cAMP/蛋白激酶-A信号传导。我们在GPR161和Ankmy2突变体之间进行了遗传上位性研究，并对刺猬途径转导蛋白Smoothened进行了Gli2/Gli3敲除、Gli3R敲入和敲除。我们还使用GPR161纤毛定位敲入突变体测试了纤毛产生的信号的作用，该突变体具有cAMP信号活性。我们发现纤毛依赖的去抑制表型有三种模式：仅缺乏GLI-R，仅过量形成GLI-A，或缺乏GLI-R或过度形成GLI-A的双重调节。这些模式大多是独立于Smoothed的。CAMP信号转导的非纤毛GPR161敲入概括了仅由于缺乏GLI-R而导致的GPR161功能丧失的组织表型。我们的结果显示了形态发生中复杂的组织特异性GLI效应器的要求，并指出了刺猬途径抑制中纤毛产生的组织特异性GLI-R阈值。总的来说，我们的研究为初级纤毛在不同组织中调节形态发生所产生的不同信号模式的合理化建立了一个概念性框架。初级纤毛是一个微小的细胞间隔，其功能类似于调节细胞信号的天线。纤毛和纤毛信号的缺陷会破坏组织结构。然而，纤毛产生的信号如何协调组织还不是很清楚。刺猬途径是一种依赖于纤毛的发育途径。在Hedgehog途径中，GLI转录因子产生互斥的激活物或抑制物。激活物和抑制物的形成都需要纤毛。然而，纤毛如何协调这些因素来调节组织结构还不清楚。在这里，我们研究了小鼠神经管和骨骼发育的缺陷，我们描述这些缺陷是由于刺猬通路缺乏纤毛抑制所致。通过研究纤毛产生的激活物或抑制物是否调节组织结果，我们揭示了纤毛输出最终协调组织的不同模式。这些模式可能是由于缺乏抑制子或过量激活剂，或由于缺乏抑制子或激活剂而产生的双重调控。缺乏纤毛特异性运输也主要是由于缺乏抑制物而调节组织的结果。总体而言，我们的研究揭示了初级纤毛组织组织结构的一般原理。
A fundamental problem in tissue morphogenesis is identifying how subcellular signaling regulates mesoscale organization of tissues. The primary cilium is a paradigmatic organelle for compartmentalized subcellular signaling. How signaling emanating from cilia orchestrates tissue organization—especially, the role of cilia-generated effectors in mediating diverse morpho-phenotypic outcomes—is not well understood. In the hedgehog pathway, bifunctional GLI transcription factors generate both GLI-activators (GLI-A) and GLI-repressors (GLI-R). The formation of GLI-A/GLI-R requires cilia. However, how these counterregulatory effectors coordinate cilia-regulated morphogenetic pathways is unclear. Here we determined GLI-A/GLI-R requirements in phenotypes arising from lack of hedgehog pathway repression (derepression) during mouse neural tube and skeletal development. We studied hedgehog pathway repression by the GPCR GPR161, and the ankyrin repeat protein ANKMY2 that direct cAMP/protein kinase-A signaling by cilia in GLI-R generation. We performed genetic epistasis between Gpr161 or Ankmy2 mutants, and Gli2/Gli3 knockouts, Gli3R knock-in and knockout of Smoothened, the hedgehog pathway transducer. We also tested the role of cilia-generated signaling using a Gpr161 ciliary localization knock-in mutant that is cAMP signaling competent. We found that the cilia-dependent derepression phenotypes arose in three modes: lack of GLI-R only, excess GLI-A formation only, or dual regulation of either lack of GLI-R or excess GLI-A formation. These modes were mostly independent of Smoothened. The cAMP signaling-competent non-ciliary Gpr161 knock-in recapitulated Gpr161 loss-of-function tissue phenotypes solely from lack of GLI-R only. Our results show complex tissue-specific GLI-effector requirements in morphogenesis and point to tissue-specific GLI-R thresholds generated by cilia in hedgehog pathway repression. Broadly, our study sets up a conceptual framework for rationalization of different modes of signaling generated by the primary cilium in mediating morphogenesis in diverse tissues. The primary cilium is a minute cellular compartment that functions like an antenna in regulating cellular signaling. Defects in cilia and ciliary signaling disrupts tissue organization. However, how signaling generated by the cilia orchestrates tissue organization is not well understood. The hedgehog pathway is a developmental pathway that is dependent on cilia. In the hedgehog pathway, the GLI transcription factors generate mutually exclusive activators or repressors. The formation of both activators and repressors requires cilia. However, how cilia coordinate these factors in regulating tissue organization is unclear. Here, we studied defects in neural tube and skeletal development in the mouse that we described to result from lack of the ciliary repression of the hedgehog pathway. By studying whether the cilia generated activators or repressors regulated the tissue outcomes, we uncovered distinct modes by which ciliary outputs finally coordinated tissue organization. These modes showed to be from lack of the repressor only, excess activator only, or from dual regulation by lack of the repressor or activator. Lack of cilium specific trafficking also predominantly regulated tissue outcomes from lack of repressor only. Overall, our study uncovers general principles by which primary cilia organize tissue architecture.
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