Open AccessQuantitation of fibroblast activation protein (FAP)‐specific protease activity in mouse, baboon and human fluids and organs
Author(s) -
Keane Fiona M.,
Yao Tsun-Wen,
Seelk Stefanie,
Gall Margaret G.,
Chowdhury Sumaiya,
Poplawski Sarah E.,
Lai Jack H.,
Li Youhua,
Wu Wengen,
Farrell Penny,
Vieira de Ribeiro Ana Julia,
Osborne Brenna,
Yu Denise M.T.,
Seth Devanshi,
Rahman Khairunnessa,
Haber Paul,
Topaloglu A. Kemal,
Wang Chuanmin,
Thomson Sally,
Hennessy Annemarie,
Prins John,
Twigg Stephen M.,
McLennan Susan V.,
McCaughan Geoffrey W.,
Bachovchin William W.,
Gorrell Mark D.
Publication year - 2014
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1016/j.fob.2013.12.001
Subject(s) - baboon , fibroblast activation protein, alpha , protease , microbiology and biotechnology , fibroblast , antibody , biology , chemistry , biochemistry , enzyme , immunology , genetics , in vitro , endocrinology , cancer
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.