Hedgehog (Hh) proteins function as morphogenes and play critical roles in pattern formation and cell growth control. Aberrant Hh signaling causes diverse types of cancers. The G protein-coupled receptor (GPCR) family protein Smoothened (Smo) is required in both insects and mammals for transduction of the Hh signal. This project uses Drosophila as a simple and genetically tractable model system to explore the mechanisms of Smo regulation at the levels of transcription and post-translation. The long-term goal of our research is to elucidate how Hh signals are sensed and transmitted to control downstream biological events that ultimately govern cell growth and patterning. Many components in Hh pathway have been identified, how the Hh signal is transduced through Patched (Ptc) to Smo is still unclear. We have discovered that Smo undergoes phosphorylation that leads to Smo cell surface accumulation and signaling activity, that sumoylation induced by Hh promotes Smo activation, and that ubiquitination downregulates Smo cell surface accumulation by promoting Smo endocytosis. Results from our studies have suggested that, in response to Hh stimulation, multiple steps occur in Smo regulation. However, many questions persist regarding the mechanism controlling Smo protein expression and activation. To address these questions, we have recently discovered that Smo transcription is regulated in specific tissue, and that a non-canonical cholesterol biosynthesis pathway regulates Smo accumulation and activation. Our published findings and preliminary studies provide new tools and hypotheses for investigating the mechanisms of Smo signaling. In this project, our central hypothesis is that reciprocal regulation of lipolysis and Hh signaling allows Smo transcription to be upregulated by a specific transcription factor and Smo protein activity to be triggered by cholesterol. We will use a combination of genetic and biochemical approaches in three Specific Aims: 1) to determine how Hh promotes lipolysis by regulating the expression of lipolysis genes; 2) to delineate the transcriptional regulation of Smo by a novel transcription factor; 3) to investigate how endogenous cholesterol biosynthesis regulates Smo.

Public Health Relevance

HEALTH RELEVANCE Hedgehog (Hh) signaling is known for its role in directing processes such as cell growth, proliferation, and differentiation during embryogenesis. Mutations in Smoothened (Smo), a critical protein in the signal reception system, results in human diseases such as basal cell carcinoma and medulloblastoma. Investigation of how Hh and Smo regulates lipid metabolism and how Smo is regulated by metabolic molecules, the goal of this project, will provide insights into developmental problems and create novel concepts of Hh signaling in cancer, obesity, and metabolic diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM079684-10
Application #
9594592
Study Section
Development - 1 Study Section (DEV1)
Program Officer
Melillo, Amanda A
Project Start
2008-07-01
Project End
2020-08-31
Budget Start
2018-09-07
Budget End
2019-08-31
Support Year
10
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Kentucky
Department
Biochemistry
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40526
Jiang, Kai; Liu, Yajuan; Zhang, Jie et al. (2018) An intracellular activation of Smoothened that is independent of Hedgehog stimulation in Drosophila. J Cell Sci 131:
Wu, Yadi; Wang, Yu; Lin, Yiwei et al. (2017) Dub3 inhibition suppresses breast cancer invasion and metastasis by promoting Snail1 degradation. Nat Commun 8:14228
Liu, Yi; Zhang, Cuiping; Li, Zhenyu et al. (2017) Latexin Inactivation Enhances Survival and Long-Term Engraftment of Hematopoietic Stem Cells and Expands the Entire Hematopoietic System in Mice. Stem Cell Reports 8:991-1004
Zhang, Jie; Liu, Yajuan; Jiang, Kai et al. (2017) SUMO regulates the activity of Smoothened and Costal-2 in Drosophila Hedgehog signaling. Sci Rep 7:42749
Li, Tongchao; Fan, Junkai; Blanco-Sánchez, Bernardo et al. (2016) Ubr3, a Novel Modulator of Hh Signaling Affects the Degradation of Costal-2 and Kif7 through Poly-ubiquitination. PLoS Genet 12:e1006054
Jiang, Kai; Liu, Yajuan; Fan, Junkai et al. (2016) PI(4)P Promotes Phosphorylation and Conformational Change of Smoothened through Interaction with Its C-terminal Tail. PLoS Biol 14:e1002375
Li, Jing; Song, Jun; Zaytseva, Yekaterina Y et al. (2016) An obligatory role for neurotensin in high-fat-diet-induced obesity. Nature 533:411-5
Jiang, Kai; Jia, Jianhang (2015) Smoothened regulation in response to Hedgehog stimulation. Front Biol (Beijing) 10:475-486
Shi, Jiandang; Liu, Yajuan; Xu, Xuehe et al. (2015) Deubiquitinase USP47/UBP64E Regulates ?-Catenin Ubiquitination and Degradation and Plays a Positive Role in Wnt Signaling. Mol Cell Biol 35:3301-11
Jiang, Kai; Jia, Jianhang (2015) Analysis of Smoothened Phosphorylation and Activation in Cultured Cells and Wing Discs of Drosophila. Methods Mol Biol 1322:45-60

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