Protease activated receptor 2 (PAR2) also known as coagulation factor II (thrombin) receptor-like 1 (F2RL1) or G-protein coupled receptor 11 (GPR11) is a protein that in humans is encoded by the F2RL1 gene. PAR2 modulates inflammatory responses,[5] obesity,[6] metabolism,[7] cancers [8][9] and acts as a sensor for proteolytic enzymes generated during infection.[10] In humans, we can find PAR2 in the stratum granulosum layer of epidermal keratinocytes. Functional PAR2 is also expressed by several immune cells such as eosinophils, neutrophils, monocytes, macrophages, dendritic cells, mast cells and T cells.[11]
Gene[edit]
The F2RL1 gene contains two exons and is widely expressed in human tissues. The predicted protein sequence is 83% identical to the mouse receptor sequence.[12]
Mechanism of activation[edit]
Activation vs silencing of PAR
PAR2 is a member of the large family of 7-transmembrane receptors that couple to guanosine-nucleotide-binding proteins. PAR2 is also a member of the protease-activated receptor family. PAR2 is activated by several different endogenous and exogenous proteases. It is activated by proteolytic cleavage of its extracellular amino terminus between arginine and serine.[13] The newly exposed N-terminus serves as tethered activation ligand, which binds a conserved region on extracellular loop 2 (ECL2) and activates the receptor.[5] These receptors can also be activated non-protealytically, by exogenous peptide sequences that mimic the final amino acids of the tethered ligand,[14] or by other proteases at cleavage sites that are not related to signaling and that can make them then irresponsive to further protease exposure.[5] Trypsin is the major PAR2 cleaving protease that initiates inflammatory signaling. It was found that even thrombin in high concentrations is able to cleave PAR2.[15] Another PAR2 cleaving protease is tryptase, the main protease of mast cells, which by PAR2 proteolytic cleavage induces calcium signaling and proliferation.[16] PARs have been identified as substrates of kallikreins, which have been related to various inflammatory and tumorigenic processes. In case of PAR2, particularly speaking about kallikrein-4, -5, -6 a -14.[17] PAR2 is known to transactivate TLR4[18] and epidermal growth factor receptor[19] in diseases.
Function[edit]
There are many studies dealing with elucidation of PAR2 function in different cells and tissues.[20] In case of human airway and lung parenchyma PAR2 is responsible for increased fibroblasts proliferation[21] and elevation of IL‐6, IL‐8, PGE2 and Ca2+ levels.[22] In mice it participates on vasodilatation.[23] Together with PAR1 its deregulation is also involved in processes of cancer cells migration and differentiation.[24]
Agonists and antagonists[edit]
Potent and selective small molecule agonists and antagonists for PAR2 have been discovered.[25][26][27]
Functional selectivity occurs with PAR2, several proteases cleave PAR2 at distinct sites leading to biased signalling.[28] Synthetic small ligands also modulate biased signalling leading to different functional responses.[29]
So far, PAR2 has been co-crystallized with two different antagonist ligands,[30] while an agonist-bound state model of PAR2 (with the endogenous ligand SLIGKV) has been determined through mutagenesis and structure-based drug design.[31]
^Rattenholl A, Steinhoff M (September 2008). "Proteinase-activated receptor-2 in the skin: receptor expression, activation and function during health and disease". Drug News & Perspectives. 21 (7): 369–81. doi:10.1358/dnp.2008.21.7.1255294. PMID 19259550.
^Kawabata A, Kanke T, Yonezawa D, Ishiki T, Saka M, Kabeya M, et al. (June 2004). "Potent and metabolically stable agonists for protease-activated receptor-2: evaluation of activity in multiple assay systems in vitro and in vivo". The Journal of Pharmacology and Experimental Therapeutics. 309 (3): 1098–107. doi:10.1124/jpet.103.061010. PMID 14976227. S2CID 10806872.
^Bar-Shavit R, Maoz M, Kancharla A, Jaber M, Agranovich D, Grisaru-Granovsky S, Uziely B (2016). "Protease-activated receptors (PARs) in cancer". G Protein-Coupled Receptors - Signaling, Trafficking and Regulation. Methods in Cell Biology. Vol. 132. pp. 341–58. doi:10.1016/bs.mcb.2015.11.006. ISBN 9780128035955. PMID 26928551.
^Gardell LR, Ma JN, Seitzberg JG, Knapp AE, Schiffer HH, Tabatabaei A, et al. (December 2008). "Identification and characterization of novel small-molecule protease-activated receptor 2 agonists". The Journal of Pharmacology and Experimental Therapeutics. 327 (3): 799–808. doi:10.1124/jpet.108.142570. PMID 18768780. S2CID 3246903.
^Barry GD, Suen JY, Le GT, Cotterell A, Reid RC, Fairlie DP (October 2010). "Novel agonists and antagonists for human protease activated receptor 2". Journal of Medicinal Chemistry. 53 (20): 7428–40. doi:10.1021/jm100984y. PMID 20873792.
Kunzelmann K, Schreiber R, König J, Mall M (2003). "Ion transport induced by proteinase-activated receptors (PAR2) in colon and airways". Cell Biochemistry and Biophysics. 36 (2–3): 209–14. doi:10.1385/CBB:36:2-3:209. PMID 12139406. S2CID 5801308.
Kawabata A (July 2002). "PAR-2: structure, function and relevance to human diseases of the gastric mucosa". Expert Reviews in Molecular Medicine. 4 (16): 1–17. doi:10.1017/S1462399402004799. PMID 14585156. S2CID 1485391.
Guyonnet Dupérat V, Jacquelin B, Boisseau P, Arveiler B, Nurden AT (July 1998). "Protease-activated receptor genes are clustered on 5q13". Blood. 92 (1): 25–31. doi:10.1182/blood.V92.1.25.413k41_25_31. PMID 9639495.
Steinhoff M, Corvera CU, Thoma MS, Kong W, McAlpine BE, Caughey GH, et al. (August 1999). "Proteinase-activated receptor-2 in human skin: tissue distribution and activation of keratinocytes by mast cell tryptase". Experimental Dermatology. 8 (4): 282–94. doi:10.1111/j.1600-0625.1999.tb00383.x. PMID 10439226. S2CID 8071759.
Loew D, Perrault C, Morales M, Moog S, Ravanat C, Schuhler S, et al. (September 2000). "Proteolysis of the exodomain of recombinant protease-activated receptors: prediction of receptor activation or inactivation by MALDI mass spectrometry". Biochemistry. 39 (35): 10812–22. doi:10.1021/bi0003341. PMID 10978167.
Knight DA, Lim S, Scaffidi AK, Roche N, Chung KF, Stewart GA, Thompson PJ (November 2001). "Protease-activated receptors in human airways: upregulation of PAR-2 in respiratory epithelium from patients with asthma". The Journal of Allergy and Clinical Immunology. 108 (5): 797–803. doi:10.1067/mai.2001.119025. PMID 11692107.
"Protease-Activated Receptors: PAR2". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2016-03-03. Retrieved 2008-12-09.
v
t
e
Cell surface receptor: G protein-coupled receptors
Class A: Rhodopsin-like
Neurotransmitter
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α1 (A
B
D)
α2 (A
B
C)
β1
β2
β3
Purinergic
Adenosine (A1
A2A
A2B
A3)
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2
4
5
6
8
9
10
11
12
13
14)
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(all but 5-HT3) 5-HT1 (A
B
D
E
F)
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B
C)
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5A
6
7)
Other
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55
119))
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2
3
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5
6)
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5
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2
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2
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D
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F
G
X1
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2
3
4
5)
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2)
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2)
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2
3
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5)
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2
3)
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2)
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Taste, bitter
TAS2R
1
3
4
5
7
8
9
10
13
14
16
19
20
30
31
38
39
40
41
42
43
45
46
50
60
Vomeronasal receptor type 1
Orphan
GPR (1
3
4
6
12
15
17
18
19
20
21
22
23
25
26
27
31
32
33
34
35
37
39
42
44
45
50
52
55
61
62
63
65
68
75
78
81
82
83
84
85
87
88
92
101
103
109A
109B
119
120
132
135
137B
139
141
142
146
148
149
150
151
152
153
160
161
162
171
173
174
176
177
182
183)
Other
Adrenomedullin
Olfactory
Opsin (3
4
5
1LW
1MW
1SW
RGR
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Protease-activated (1
2
3
4)
SREB (1
2
3)
Class B: Secretin-like
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ADGRB
Brain-specific angiogenesis inhibitor
1
2
3
ADGRC
Cadherin
1
2
3
ADGRE
EMR
1
2
3
CD97
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1
2
3
4
5
6
7
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1
2
3
ELTD1
Orphan
GPR (56
64
97
98
110
111
112
113
114
115
116
123
124
125
126
128
133
143
144
155
157)
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3
Vomeronasal receptor, type 2
Other
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2)
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2
3
4
5
6
7
8))
GPRC6A
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158
179)
RAIG (1
2
3
4)
Class F: Frizzled & Smoothened
Frizzled
Frizzled (1
2
3
4
5
6
7
8
9
10)
Smoothened
Smoothened
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
This article is licensed under CC BY-SA 3.0. Original source: https://en.wikipedia.org/wiki/Protease-activated receptor 2 Status: article is cached