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Keane FM, Yao TW, Seelk S, Gall MG, Chowdhury S, Poplawski SE, Lai JH, Li Y, Wu W, Farrell P, Vieira de Ribeiro AJ, Osborne B, Yu DMT, Seth D, Rahman K, Haber P, Topaloglu AK, Wang C, Thomson S, Hennessy A, Prins J, Twigg SM, McLennan SV, McCaughan GW, Bachovchin WW, Gorrell MD. Quantitation of fibroblast activation protein (FAP)-specific protease activity in mouse, baboon and human fluids and organs. FEBS Open Bio 2013; 4:43-54. [PMID: 24371721 PMCID: PMC3871272 DOI: 10.1016/j.fob.2013.12.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 12/04/2013] [Accepted: 12/04/2013] [Indexed: 02/08/2023] Open
Abstract
The protease fibroblast activation protein (FAP) is a specific marker of activated mesenchymal cells in tumour stroma and fibrotic liver. A specific, reliable FAP enzyme assay has been lacking. FAP's unique and restricted cleavage of the post proline bond was exploited to generate a new specific substrate to quantify FAP enzyme activity. This sensitive assay detected no FAP activity in any tissue or fluid of FAP gene knockout mice, thus confirming assay specificity. Circulating FAP activity was ∼20- and 1.3-fold less in baboon than in mouse and human plasma, respectively. Serum and plasma contained comparable FAP activity. In mice, the highest levels of FAP activity were in uterus, pancreas, submaxillary gland and skin, whereas the lowest levels were in brain, prostate, leukocytes and testis. Baboon organs high in FAP activity included skin, epididymis, bladder, colon, adipose tissue, nerve and tongue. FAP activity was greatly elevated in tumours and associated lymph nodes and in fungal-infected skin of unhealthy baboons. FAP activity was 14- to 18-fold greater in cirrhotic than in non-diseased human liver, and circulating FAP activity was almost doubled in alcoholic cirrhosis. Parallel DPP4 measurements concorded with the literature, except for the novel finding of high DPP4 activity in bile. The new FAP enzyme assay is the first to be thoroughly characterised and shows that FAP activity is measurable in most organs and at high levels in some. This new assay is a robust tool for specific quantitation of FAP enzyme activity in both preclinical and clinical samples, particularly liver fibrosis. A novel synthetic fluorogenic substrate is proven to be FAP-specific. Mice have higher levels of circulating FAP activity compared to baboons or humans. No FAP activity was detected in urine or bile but bile contained high DPP4 activity. FAP activity is greatest in pancreas, uterus, salivary gland, skin and lymph node. FAP activity and protein is elevated in both serum and liver in human liver disease.
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Key Words
- ALD, alcoholic liver disease
- AMC, amino-4-methylcoumarin
- Biomarker
- DMSO, dimethyl sulfoxide
- DPP4, dipeptidyl peptidase 4
- Dipeptidyl peptidase
- EDTA, ethylene diamine tetra acetic acid
- FAP, fibroblast activation protein-α
- Fibroblast
- Fibrosis
- HCV, hepatitis C virus
- LDS, lithium dodecyl sulphate
- LN, lymph node
- Liver disease
- ND, non-diseased
- PBC, primary biliary cirrhosis
- PBMC, peripheral blood mononuclear cells
- PBS, phosphate-buffered saline
- PEP, prolyl endopeptidase
- PVDF, polyvinylidene fluoride
- Protease activity
- Protease substrates
- STLV, simian T-cell lymphotrophic virus
- gko, gene knock out
- het, heterozygous
- mAb, monoclonal antibody
- wt, wild type
- yrs, years
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Affiliation(s)
- Fiona M Keane
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | - Tsun-Wen Yao
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | | | - Margaret G Gall
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | - Sumaiya Chowdhury
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | - Sarah E Poplawski
- Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
| | - Jack H Lai
- Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
| | - Youhua Li
- Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
| | - Wengen Wu
- Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
| | - Penny Farrell
- Department of Renal Medicine, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Ana Julia Vieira de Ribeiro
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | - Brenna Osborne
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | - Denise M T Yu
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | - Devanshi Seth
- Centenary Institute, Camperdown, NSW, Australia ; Drug Health Services, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Khairunnessa Rahman
- Drug Health Services, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Paul Haber
- Sydney Medical School, University of Sydney, NSW, Australia ; Drug Health Services, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - A Kemal Topaloglu
- Pediatric Endocrinology, Faculty of Medicine, Cukurova University, Adana, Turkey
| | - Chuanmin Wang
- Sydney Medical School, University of Sydney, NSW, Australia ; Collaborative Transplantation Research Group, Bosch Institute, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Sally Thomson
- Sydney Medical School, University of Sydney, NSW, Australia ; Department of Renal Medicine, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Annemarie Hennessy
- Department of Renal Medicine, Royal Prince Alfred Hospital, Camperdown, NSW, Australia ; School of Medicine, University of Western Sydney, NSW, Australia
| | - John Prins
- Mater Medical Research Institute, University of Queensland, and Department of Endocrinology, Princess Alexandra Hospital, Brisbane, QLD, Australia
| | - Stephen M Twigg
- Sydney Medical School, University of Sydney, NSW, Australia ; Department of Endocrinology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Susan V McLennan
- Sydney Medical School, University of Sydney, NSW, Australia ; Department of Endocrinology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Geoffrey W McCaughan
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
| | - William W Bachovchin
- Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
| | - Mark D Gorrell
- Centenary Institute, Camperdown, NSW, Australia ; Sydney Medical School, University of Sydney, NSW, Australia
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