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Grzelak CA, Sigglekow ND, Tirnitz-Parker JEE, Hamson EJ, Warren A, Maneck B, Chen J, Patkunanathan B, Boland J, Cheng R, Shackel NA, Seth D, Bowen DG, Martelotto LG, Watkins DN, McCaughan GW. Widespread GLI expression but limited canonical hedgehog signaling restricted to the ductular reaction in human chronic liver disease. PLoS One 2017; 12:e0171480. [PMID: 28187190 PMCID: PMC5302813 DOI: 10.1371/journal.pone.0171480] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 01/20/2017] [Indexed: 12/13/2022] Open
Abstract
Canonical Hedgehog (Hh) signaling in vertebrate cells occurs following Smoothened activation/translocation into the primary cilia (Pc), followed by a GLI transcriptional response. Nonetheless, GLI activation can occur independently of the canonical Hh pathway. Using a murine model of liver injury, we previously identified the importance of canonical Hh signaling within the Pc+ liver progenitor cell (LPC) population and noted that SMO-independent, GLI-mediated signals were important in multiple Pc-ve GLI2+ intrahepatic populations. This study extends these observations to human liver tissue, and analyses the effect of GLI inhibition on LPC viability/gene expression. Human donor and cirrhotic liver tissue specimens were evaluated for SHH, GLI2 and Pc expression using immunofluorescence and qRT-PCR. Changes to viability and gene expression in LPCs in vitro were assessed following GLI inhibition. Identification of Pc (as a marker of canonical Hh signaling) in human cirrhosis was predominantly confined to the ductular reaction and LPCs. In contrast, GLI2 was expressed in multiple cell populations including Pc-ve endothelium, hepatocytes, and leukocytes. HSCs/myofibroblasts (>99%) expressed GLI2, with only 1.92% displaying Pc. In vitro GLI signals maintained proliferation/viability within LPCs and GLI inhibition affected the expression of genes related to stemness, hepatocyte/biliary differentiation and Hh/Wnt signaling. At least two mechanisms of GLI signaling (Pc/SMO-dependent and Pc/SMO-independent) mediate chronic liver disease pathogenesis. This may have significant ramifications for the choice of Hh inhibitor (anti-SMO or anti-GLI) suitable for clinical trials. We also postulate GLI delivers a pro-survival signal to LPCs whilst maintaining stemness.
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Affiliation(s)
| | | | | | - Elizabeth Jane Hamson
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
| | - Alessandra Warren
- Ageing and Alzheimers Institute, Centre for Education and Research on Ageing, University of Sydney, Concord Hospital, Sydney, New South Wales, Australia
- ANZAC Research Institute, University of Sydney, Concord Hospital, Sydney, New South Wales, Australia
| | - Bharvi Maneck
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
- A.W. Morrow Gastroenterology and Liver Centre, R.P.A.H., Camperdown, New South Wales, Australia
| | - Jinbiao Chen
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
| | | | - Jade Boland
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
| | - Robert Cheng
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
| | - Nicholas Adam Shackel
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
- A.W. Morrow Gastroenterology and Liver Centre, R.P.A.H., Camperdown, New South Wales, Australia
- Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia
| | - Devanshi Seth
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
| | - David Geoffrey Bowen
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
- A.W. Morrow Gastroenterology and Liver Centre, R.P.A.H., Camperdown, New South Wales, Australia
| | - Luciano Gastón Martelotto
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - D. Neil Watkins
- The Kinghorn Cancer Centre, Garvan Institute, Darlinghurst, New South Wales, Australia
| | - Geoffrey William McCaughan
- Liver Injury and Cancer, Centenary Institute, Camperdown, New South Wales, Australia
- A.W. Morrow Gastroenterology and Liver Centre, R.P.A.H., Camperdown, New South Wales, Australia
- Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia
- * E-mail:
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