Composition and molecular architecture of the sonic hedgehog morphogen
Abstract/Contents
- Abstract
- The Hedgehog signaling pathway performs essential and diverse roles in embryonic development and adult tissue homeostasis throughout the animal kingdom. Hedgehog proteins are secreted morphogens that emanate from localized pools of cells, generating a concentration gradient that communicates positional information to the cells within the tissue. A distinctive feature of Hedgehog proteins is covalent modification with a N-terminal palmitate and a C-terminal cholesterol, which strongly tether Hedgehog to cell membranes and modulate its distribution in tissues. Despite this hydrophobic character, Hedgehog proteins mobilize from expressing cells and travel far from their source to act directly upon distant responding cells. Although evidence exists for multiple mechanisms of Hedgehog mobilization, the actual physical form of the Hedgehog morphogen, as it is packaged and deployed in tissues, remains unknown. Studies in zebrafish have revealed a secreted factor, Scube2, that functions non-cell-autonomously to enable Hedgehog signaling. This led to the discovery that the mouse Scube2 protein can drive release of fully-lipidated Sonic Hedgehog from cell membranes in a soluble form that is potent in signaling assays. In this study, we have taken advantage of Scube2 activity to investigate the physical form of the active Shh morphogen. The signaling activity of this Scube2-released ShhNp is associated predominantly with a large, but discrete, protein complex approximately 250-300 kilodaltons in size. Further analysis suggests that this consists largely of a Scube2:Shh complex, although fully-lipidated Shh could also be present in other forms. Exracellular matrix glycans, such as heparan sulfate, contribute to the assembly and release of soluble, high molecular weight form of Shh by Scube2, and a heparin chain of 16 units suffices to potentiate Scube2-mediated release of ShhNp. This defined system has allowed us to produce large quantities of active morphogen for analysis, thus enabling us to begin addressing questions about the composition, stoichiomentry, and molecular architecture of the active morphogen.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2014 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Saunders, Adam Michael |
|---|---|
| Associated with | Stanford University, Department of Developmental Biology. |
| Primary advisor | Beachy, Philip Arden |
| Thesis advisor | Beachy, Philip Arden |
| Thesis advisor | Nusse, Roel, 1950- |
| Thesis advisor | Shapiro, Lucy |
| Thesis advisor | Villeneuve, Anne, 1959- |
| Advisor | Nusse, Roel, 1950- |
| Advisor | Shapiro, Lucy |
| Advisor | Villeneuve, Anne, 1959- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Adam Michael Saunders. |
|---|---|
| Note | Submitted to the Department of Developmental Biology. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2014. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2014 by Adam Michael Saunders
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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