The Hedgehog (Hh) signal transduction pathway plays an essential role in patterning fields of cells during development, and is frequently activated in cancer. Inappropriate Hh signaling is causative in basal cell carcinoma, the most common cancer in humans, medulloblastoma, the most common malignant brain tumor in children, and rhabdomyosarcoma, where pathway activation correlates with poor prognosis. Hh has also been implicated in sporadic tumors of the lung, breast and prostate. Consequently, the Hh pathway has emerged as an attractive therapeutic target; specific inhibition of Hh signaling will likely have efficacy against these cancers without triggering the undesirable side effects associated with conventional chemotherapy. To design and employ Hh-specific therapies, a clear understanding of the regulatory mechanisms and signaling components controlling physiological Hh signal transduction is of paramount importance. Accordingly, the goals of this proposal are to dissect mechanistic events governing Hh pathway induction and to identify novel effectors facilitating downstream signaling. We will achieve these goals through molecular and functional analysis of Hh signal transduction using the fruit fly Drosophila melanogaster as our model system. Our studies primarily focus on elucidating the signaling mechanisms and downstream effectors of Smoothened, the critical signal transducer of the Hh pathway. Smoothened is a member of the G-protein coupled receptor (GPCR) superfamily. As such, this study includes three Specific Aims designed to better characterize Smoothened GPCR signaling activity: 1) To characterize the extracellular GPCR structural features that facilitate Hh- regulated Smoothened signaling, 2) To identify GPCR functional domains in Smoothened that govern signaling and 3) To map the G-protein effector network functioning downstream of Smoothened. The proposed studies will enhance our understanding of how the Hh signal is initiated and transduced, and may reveal novel therapeutic targets through identifying pressure points on Smoothened and within the Hh cascade.

Public Health Relevance

The Hedgehog (Hh) signal transduction pathway plays an essential role in patterning fields of cells during development, and is frequently activated in cancer. Inappropriate Hh signaling is causative in basal cell carcinoma, the most common cancer in humans, medulloblastoma, the most common malignant brain tumor in children, and rhabdomyosarcoma, where pathway activation correlates with poor prognosis. Hh has also been implicated in sporadic tumors of the lung, breast and prostate. Consequently, the Hh pathway has emerged as an attractive therapeutic target; specific inhibition of Hh signaling will likely have efficacy against these cancers without triggering the undesirable side effects associated with conventional chemotherapy. To design and employ Hh-specific therapies, a clear understanding of the regulatory mechanisms and signaling components controlling physiological Hh signal transduction is of paramount importance. Accordingly, the goals of this proposal are to dissect mechanistic events governing Hh pathway induction and to identify novel effectors facilitating downstream signaling. We will achieve these goals through molecular and functional analysis of Hh signal transduction using the fruit fly Drosophila melanogaster as our model system. The proposed studies will enhance our understanding of how the Hh signal is initiated and transduced, and may reveal novel therapeutic targets through identifying 'pressure points' within the Hh cascade.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
4R01GM101087-05
Application #
9060956
Study Section
Intercellular Interactions Study Section (ICI)
Program Officer
Dunsmore, Sarah
Project Start
2012-08-01
Project End
2017-04-30
Budget Start
2016-05-01
Budget End
2017-04-30
Support Year
5
Fiscal Year
2016
Total Cost
Indirect Cost
Name
St. Jude Children's Research Hospital
Department
Type
DUNS #
067717892
City
Memphis
State
TN
Country
United States
Zip Code
38105
Arensdorf, Angela M; Dillard, Miriam E; Menke, Jacob M et al. (2017) Sonic Hedgehog Activates Phospholipase A2 to Enhance Smoothened Ciliary Translocation. Cell Rep 19:2074-2087
Marzahn, Melissa R; Marada, Suresh; Lee, Jihun et al. (2016) Higher-order oligomerization promotes localization of SPOP to liquid nuclear speckles. EMBO J 35:1254-75
Marada, Suresh; Truong, Ashley; Ogden, Stacey K (2016) The small GTPase Rap1 is a modulator of Hedgehog signaling. Dev Biol 409:84-94
Marada, Suresh; Truong, Ashley; Ogden, Stacey K (2016) Dataset for phenotypic classification of genetic modifiers of smoothened and Hedgehog. Data Brief 7:485-9
Arensdorf, Angela M; Marada, Suresh; Ogden, Stacey K (2016) Smoothened Regulation: A Tale of Two Signals. Trends Pharmacol Sci 37:62-72
Ogden, Stacey K (2015) Genetic evidence for a Smoothened-G?(i) signaling axis in mammals. Sci Signal 8:fs16
Marada, Suresh; Navarro, Gemma; Truong, Ashley et al. (2015) Functional Divergence in the Role of N-Linked Glycosylation in Smoothened Signaling. PLoS Genet 11:e1005473
Marada, Suresh; Stewart, Daniel P; Bodeen, William J et al. (2013) The unfolded protein response selectively targets active smoothened mutants. Mol Cell Biol 33:2375-87
Rana, Rajashree; Carroll, Candace E; Lee, Ho-Jin et al. (2013) Structural insights into the role of the Smoothened cysteine-rich domain in Hedgehog signalling. Nat Commun 4:2965