The Hedgehog (Hh) family of secreted signaling molecules plays an important role in cell fate specification, cell proliferation and differentiation. Dysfunction in Hh signaling results in abnormal embryonic development and several types of cancer in human;thus, understanding the molecular mechanisms of Hh signal transduction is of great significance for the prevention and remedy of the birth defects and cancers caused by aberrant Hh signaling. In mice, Gli2 and Gli3 zinc-finger-containing transcription factors are the primary mediators of Hh signaling. In the absence of a Hh signal, most full-length Gli3 protein (Gli3FL) is proteolytically processed to a transcriptional repressor (Gli3Rep). Gli3 processing requires C-terminal phosphorylation by protein kinase A (PKA), glycogen synthase kinase 3 (GSK3), and casein kinase 1 (CK1), and subsequent ubiquitination by SCFTrCP E3 ubiquitin ligase. Polyubiquitinated Gli3 is then processed by the proteasome. Gli3FL is predominantly localized in the cytoplasm and shuttles between the cytoplasm and nucleus, while Gli3Rep is exclusively found in the nucleus. Hh signaling counters Gli3 processing through an unknown mechanism and converts Gli3FL into an activator, Gli3Act, thus derepressing Hh target genes. The stability of Gli3, as well as Gli2, is also tightly controlled. To date, little is known at the molecular level about how Hh signaling regulates Gli3 processing, nuclear translocation, or Gli2 and Gli3 stability. Genetic and limited biochemical evidence indicates that Hh signaling regulates these molecular events through various effector molecules, though the connections between these effectors and Gli proteins are unknown. Many of these effectors are vertebrate specific, although some are conserved in Drosophila. Our objectives are to determine the role of these effectors in Hh signaling and the molecular mechanisms by which they regulate Gli2 and Gli3 function. Specifically, Aim 1 will understand the role of Dzip1 in the regulation of Gli3 function, Aim 2 will elucidate the molecular mechanism of Gli3 processing using intraflagellar transport (IFT) and Dynein gene mutants, and Aim 3 will understand the molecular basis of the Hh pathway activation in Sufu mutant. The completion of the proposed studies will significantly advance our understanding of the regulation and function of Gli3 protein in Hh signaling.

Public Health Relevance

The Hedgehog (Hh) family of secreted signaling proteins plays fundamental roles in cell fate specification and cell proliferation and differentiation. Loss of Hh signaling results in a wide range of birth defects, whereas aberrant activation of the Hh pathway causes several types of human cancer. Understanding the molecular mechanism of Hh signaling may provide insights into the design of therapeutic agents to modulate Hh pathway activity and therefore prevent or treat birth defects and cancers caused by misregulation of the Hh signaling activity.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA111673-08
Application #
8089450
Study Section
Development - 2 Study Section (DEV2)
Program Officer
Mietz, Judy
Project Start
2004-05-01
Project End
2014-05-31
Budget Start
2011-06-01
Budget End
2012-05-31
Support Year
8
Fiscal Year
2011
Total Cost
$295,380
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Genetics
Type
Schools of Medicine
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Wu, Chuanqing; Yang, Mei; Li, Juan et al. (2014) Talpid3-binding centrosomal protein Cep120 is required for centriole duplication and proliferation of cerebellar granule neuron progenitors. PLoS One 9:e107943
Wang, Chengbing; Low, Wee-Chuang; Liu, Aimin et al. (2013) Centrosomal protein DZIP1 regulates Hedgehog signaling by promoting cytoplasmic retention of transcription factor GLI3 and affecting ciliogenesis. J Biol Chem 288:29518-29
Cao, Ting; Wang, Chengbing; Yang, Mei et al. (2013) Mouse limbs expressing only the Gli3 repressor resemble those of Sonic hedgehog mutants. Dev Biol 379:221-8
Wilson, Sandra L; Wilson, John P; Wang, Chengbing et al. (2012) Primary cilia and Gli3 activity regulate cerebral cortical size. Dev Neurobiol 72:1196-212
Han, Lizhang; Pan, Yong; Wang, Baolin (2012) Small ubiquitin-like Modifier (SUMO) modification inhibits GLI2 protein transcriptional activity in vitro and in vivo. J Biol Chem 287:20483-9
Li, Juan; Wang, Chengbing; Pan, Yong et al. (2011) Increased proteolytic processing of full-length Gli2 transcription factor reduces the hedgehog pathway activity in vivo. Dev Dyn 240:766-74
Cui, Cheng; Chatterjee, Bishwanath; Francis, Deanne et al. (2011) Disruption of Mks1 localization to the mother centriole causes cilia defects and developmental malformations in Meckel-Gruber syndrome. Dis Model Mech 4:43-56
Wang, Chengbing; Pan, Yong; Wang, Baolin (2010) Suppressor of fused and Spop regulate the stability, processing and function of Gli2 and Gli3 full-length activators but not their repressors. Development 137:2001-9
Low, Wee-Chuang; Wang, Chengbing; Pan, Yong et al. (2008) The decoupling of Smoothened from Galphai proteins has little effect on Gli3 protein processing and Hedgehog-regulated chick neural tube patterning. Dev Biol 321:188-96
Wang, Chengbing; Ruther, Ulrich; Wang, Baolin (2007) The Shh-independent activator function of the full-length Gli3 protein and its role in vertebrate limb digit patterning. Dev Biol 305:460-9

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