Kallikrein in the Interstitial Space | 6 | Proteolysis in the Intersti

ABSTRACT

Kallikrein is a functional activity defined by the ability of kallikreins (kininogenases) to form kinins (vasoactive peptides) from kininogens. ¹ Early work defined two types of kallikrein, plasma kallikrein (KLK-B1) and tissue (glandular) kallikrein (KLK-1), which differed in distribution, size, and specificity. KLK-B1 (PK) is a plasma protein with a molecular weight of 80–90 kDa depending on the extent of glycosylation, while KLK-1 (TK) has a molecular weight of approximately 40 kDa. ² More recent work has identified KLK-1 as a member of a family described as kallikrein-like peptidases (KLKs; Table 6.1). ³ Both KLK-B1 and KLK-1 are synthesized as precursor or zymogen forms—prekallikrein in the case of KLK-B1 and prokallikrein in the case of KLK-1—which require activation for full activity (Figure 6.1). Table 6.1 Kallikrein-Related Peptidases in the Interstitial Space

Kailikrein-Reiated Peptidase ^a	Specificity	Potential Substrates in the Interstitium ^b	Refs.
KLK-1 (classical tissue or glandular kallikrein; primary sites of synthesis in pancreas, kidney, and salivary glands; wide tissue distribution ¹ ^, ² ^, ³ )	Cleavage of arginine–serine and methionine–lysine peptide bonds in kininogens; synthetic substrates include chromogenic arginine and lysine peptide nitroanilides ⁴ ^, ⁵	Kininogen, ⁶ ^, ⁷ VEGF, ⁸ MMP zymogen, ⁹ ^, ¹⁰ IGFBP, ¹¹ PAR, ¹² pro-KLK-2, ¹³ pro-KLK-4, ¹³ pro-KLK-5, ¹³ pro-KLK-6, ¹³ pro-KLK-12, ¹³ pro-KLK-14 ¹³	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
KLK-2 (human glandular kallikrein 1; exclusive in the prostate ¹ )	Strict specificity for arginine-containing peptide bonds ¹⁴	IGFBP-3, ¹⁵ fibronectin, ¹⁶ ^, ¹⁷ PSA, ¹⁶ ^, ¹⁸ semenogelin I, ¹⁷ semenogelin II, ¹⁷ uPA zymogen, ¹⁹ pro-KLK-2, ¹³ pro-KLK-4, ¹³ KLK-12, ¹³ KLK-14 ¹³	1, 14, 15, 16, 17, 18, 19
KLK-3 (prostate-specific antigen; exclusive in prostate ¹ ) ^c	Cleavage at tyrosine-, phenylalanine-, and leucine-containing peptide bonds (chymotryptic-like specificity) ²⁰ ^, ²¹	May have antiangiogenic activity, ²² ^, ²³ pro-KLK-2, ¹³ pro-KLK-4, ¹² pro-KLK-5, ¹³ pro-KLK-6, ¹³ pro-KLK-7, ¹³ pro-KLK-12, ¹³ pro-KLK-14 ¹³	1, 20, 21, 22, 23
KLK-4 (prostase; wide distribution, ¹ including prostate and enamel; ²⁴ ^, ²⁵ expressed in ovarian cancer ²⁴ ^, ²⁶ )	Preference for arginine-containing peptide bonds ²⁷ ^, ²⁸	PAR-1, ²⁹ prourokinase, ³⁰ ^, ³¹ pro-KLK-11, ³⁰ pro-KLK-3, ³¹ uPAR, ³² enamelin, ³³ , ^d amelogenin, ³⁴ metalloproteinase meprin β ³⁵	1, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
KLK-5 (human stratum corneum tryptic enzyme [SCTE]; found in skin and breast tissue; ¹ ^, ³⁶ ovarian cancer ³⁷ )	Preference for cleavage of arginine peptide bonds; also cleavage of lysine peptide bonds ³⁸	Profilaggrin, ³⁹ PAR-2, ⁴⁰ plasminogen, ⁴¹ human-adapted influenza virus, ⁴² metalloproteinase meprin a and β, ³⁵ pro-KLK-5, ¹³ pro-KLK-14 ¹³	1, 36, 37, 38, 39, 40, 41, 42
KLK-6 (protease M; found in brain, pancreas; ¹ ^, ⁴³ proposed biomarker for ovarian cancer, brain trauma ⁴⁴ ^, ⁴⁵ )	Preference for arginine peptide bonds; less for lysine in physiological substrates; broader specificity with peptide substrates ²⁷ ^, ²⁸	Autoactivation, ⁴⁶ ^, ⁴⁷ fibrinogen, ⁴⁷ collagen, ⁴⁷ ^, ⁴⁸ plasminogen, ⁴⁷ vitronectin, ⁴⁸ PAR-1, ⁴⁹ ^, ⁵⁰ PAR-2, ⁴⁹ pro-KLK-4, ¹³ pro-KLK-5 ¹³	1, 43, 44, 45, 46, 47, 48, 49, 50
KLK-7 (human stratum corneum chymotryptic enzyme [SCCE]; found in skin, esophagus, heart, pancreas ¹ ^, ⁵¹ ^, ⁵² )	Preference for tyrosine peptide bonds (chymotryptic-like specificity); ²⁷ ^, ²⁸ ^, ⁵³ activated by metalloproteinases meprin a or β ³⁵	Interleukin-1 β, ⁵⁴ E-cadherin, ⁵⁵ fibronectin, ⁵⁶ uPAR, ⁵⁷ desmoglein 2, ⁵⁸ pro-MMP-9, ⁵⁹ caspase 14, ⁶⁰ prochemerin, ⁶¹ pro-KLK-5 ¹³	1, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61
KLK-8 (neuropsin; found in brain, skin, breast ¹ ^, ⁶² ^– ⁶⁶ )	Preference for cleavage of arginine peptide bonds	PAR-1, ⁶⁷ ,^, ^e PAR-2, ⁶⁷ fibronectin, ⁶⁸ collagen IV, ⁶⁸ fibrinogen, ⁶⁸ HMWK, ⁶⁸ single-chain tPA, ⁶⁸ ephrin type-B receptor 2 (EphB2), ⁶⁹ meprin β ³⁵	1, 62, 63, 64, 65, 66, 67, 68, 69
KLK-9 (wide tissue distribution; ¹ ^, ⁷⁰ ^– ⁷² ovarian tumors, ⁷³ breast tumors ⁷⁴ )	Preference for arginine peptide bonds	pro-KLK-2, ¹³ ^, ⁷⁵ pro-KLK-4, ¹³ pro-KLK-5, ¹³ pro-KLK-11, ¹³ pro-KLK-12, ¹³ pro-KLK-13, ¹³ pro-KLK-14 ¹³	1, 70, 71, 72, 73, 74, 75
KLK-10 (normal epithelial cell–specific 1 [NES1]; serine protease; wide tissue distribution ¹ ^, ⁷⁶ ^– ⁸³ )	Preference for arginine peptide bonds; cleavage also at lysine peptide bonds	pro-KLK-14, ¹³ measurement of expression is based on immunohistochemistry or nucleic acid technology (RT-PCR) ^f	1, 76, 77, 78, 79, 80, 81, 82, 83
KLK-11 (hippostasin; trypsin-like serine protease [TLSP]; wide tissue distribution ¹ with various isoforms^– ⁸⁴ ^– ⁸⁷ )	Preference for arginine peptide bonds in physiological substrates; cleavage of methionine, lysine peptide bonds in combinatorial peptide library ²⁷	IGFBP-3, ⁸⁸ pro-KLK-4, ¹³ pro-KLK-5, ¹³ pro-KLK-12, ¹³ pro-KLK-14 ¹³	1, 84, 85, 86, 87, 88
KLK-12 (KLK-like 5; first identified by sequence analysis of the chromosomal region, encoding other members of the KLK family; may have isoforms showing wide tissue distribution ¹ ^, ⁸⁹ ^– ⁹² )	Tryptic-like specificity for cleavage of arginine and lysine peptide bonds ⁹³	pro-KLK-12, ⁹³ ^, ^g pro-KLK-11, ⁹³ CCN family of matricellular proteins, ⁹⁴ , ^h human-adapted influenza virus, ⁴³ membrane-bound platelet-derived growth factor B, ⁹⁵ HMWK ⁹⁶ ^, ⁱ	1, 89, 90, 91, 92, 93, 94, 95, 96
KLK-13 (KLK-L4) ¹ ^, ⁹² ^, ⁹⁷ ^– ¹⁰⁰	Specificity for the cleavage of arginine and lysine peptide bonds; ⁹⁷ activated by citrate, sulfate, and heparin ^j	Histatin C, ¹⁰¹ , ^k myelin basic proteins, ¹⁰¹ , ^k HMWK, ⁹⁹ ^, ^l ECM proteins; ¹⁰² , ^m also inhibited by several members of the serpin family ¹⁰³ ^, ¹⁰⁴ , ⁿ	1,92,97, 98, 99, 100, 101, 102, 103, 104
KLK-14 (KLK-L6; wide tissue distribution ¹ ^, ¹⁰⁵ ^, ¹⁰⁶ )	Specificity for the cleavage of arginine and lysine peptides bonds with preference for arginine peptide bonds; ¹⁰⁷ ^– ¹¹⁰ proenzyme form activated by KLK-5 ¹³ ^, ¹⁰⁵	PAR-2, ⁴¹ ^, ⁶⁵ ^, ¹⁰⁹ fibronectin, ¹⁰⁷ collagen I, ¹⁰⁷ collagen IV, ¹⁰⁷ fibrinogen, ¹⁰⁷ HMWK, ¹⁰⁷ IGFBP-3, ¹⁰⁷ pro-KLK-1, ¹¹¹ pro-KLK-3, ¹¹¹ pro-KLK-5, ¹¹² pro-KLK-11, ¹¹¹ latent TGF-β1, ¹¹³ complement factor C3 ¹¹⁴	1,105, 106, 107, 108, 109, 110, 111, 112, 113, 114
KLK-15 (prostin; prostinogen; ACO protease; hK15; found in prostate, colon, thyroid ¹ ^, ¹¹⁵ ^– ¹¹⁷ )	Preference for cleavage of arginine and lysine peptide bonds; ⁷⁵ ^, ¹¹⁵ ^, ¹¹⁷ presence of glutamic acid residue instead of aspartic acid residue at position 189 ¹¹⁵ in amino acid sequence may promote preference for cleavage at lysine peptide bonds ⁷⁵ ^, ¹¹⁹	pro-KLK-3 (pro-PSA), ¹¹⁵ ^, ¹¹⁷ pro-KLK-1, ¹¹⁷ pro-KLK-2, ¹¹⁷ pro-KLK-7, ¹¹⁷ pro-KLK-8, ¹¹⁷ pro-KLK-9, ¹¹⁷ pro-KLK-14, ¹¹⁷ pro-KLK-15 (autocatalytic activation) ¹¹⁷ ^, ¹¹⁸	1, 115, 116, 117, 118, 119
Plasma kallikrein (KLK-B1; formed from plasma prekallikrein [Fletcher factor]; primary site of synthesis in hepatocytes but found in a number of other tissues, including brain; ¹²⁰ ^, ¹²¹ increased expression in monocytes suggested as biomarker for CLL ¹²² )	Preference for arginine and lysine peptide bonds	Substrates include HMWK, ¹²³ , ^o pro-uPA, ¹²⁴ PK-120 glycoprotein, ¹²⁵ ECM proteins contained in astrocyte secretome ¹²⁶	120, 121, 122, 123, 124, 125, 126

Note: This table is a listing of human KLKs. The rat and mouse KLK family is somewhat more complex (see Lundwall, A., et al., Biol. Chem. 387, 637–641, 2006). The reader is directed to several recent reviews for additional information on this family of proteases (Rawlings, N.D. and Barrett, A.J., Introduction: Serine peptidases and their clans, in Handbook of Proteolytic Enzymes, 3rd edn., eds. N.D. Rawlings and G. Salvesen, Chapter 559, pp. 2491–2525, Academic Press/Elsevier, Amsterdam, the Netherlands, 2013; Clements, J.A., et al., The human tissue kallikrein and kallikrein-related peptidase family, in Handbook of Proteolytic Enzymes, 3rd edn., eds. N.D. Rawlings and G. Salvesen, Chapter 606, pp. 2809–2813, Academic Press/Elsevier, Amsterdam, the Netherlands, 2013). It is noted that there has only been direct measurement of KLK-1 and KLK-B1 in lymph, presumably derived from interstitial fluid. a

This is a compilation of the various human KLKs (Lundwall, A. and Brattsand, M., Kallikrein-related peptidases, Cell. Mol. Life. Sci. 65, 2019–2038, 2008; Clements, J.A., et al., The human tissue kallikrein and kallikrein-related peptidase family, in Handbook of Proteolytic Enzymes, Vol. 3., eds. N.D. Rawlings and G. Salvesen, Chapter 606, pp. 2747–2756, Elsevier/Academic Press, Amsterdam, the Netherlands, 2013) as well as KLK-B1 (Björkqvist, J., et al., Thromb. Haemost. 110, 399–407, 2013).

This is a listing of potential substrates for individual KLKs based on in vitro demonstration of cleavage(s). There is an absence of data supporting in vivo action. It should also be noted that the in vitro assays do not necessarily reflect the in vivo interstitial environment. For example, while hyaluronan is a major component of the interstitial space, we could not find any in vitro studies that included this anionic polymer, notwithstanding the several examples of an effect of polyvalent anions. A number of the cited studies suggest a cascade for the interaction of various kallikreins and prokallikreins, such as those proposed for blood coagulation and complement formation (Neurath, H. and Walsh, K.A., Proc. Nal. Acad. Sci. USA 73, 3825–3832, 1976). The formation of activation complexes that results in the removal of reactants from bulk solution to a local environment (e.g., Mann, K.G., et al., Annu. Rev. Biochem. 57, 915–956, 1988) greatly increases the catalytic efficiency of such processes. It is not unlikely that such complexes might function in the kallikrein cascades (Pampalakis, G. and Sotiropoulou, G., Biochim. Biophys. Acta 1776, 22–31, 2007). It is most likely that the physiological action of kallikrein(s) is at the local level in autocrine or paracrine action (Ma, J.X., et al., Exp. Eye Res. 63, 19–26, 1996).

KLK-3 is better known as PSA, a diagnostic/prognostic biomarker for prostate cancer (Garg, V., et al., Expert Rev. Pharmacoecon. Outcomes Res. 13, 327–342, 2013).

Only genetic evidence is available to support the importance of KLK-4 in humans; there are data on the processing of 32 kDa enamelin by KLK-4 (Yamakoshi, Y., et al., Eur. J. Oral Sci. 114[Suppl. 1], 45–51, 2006).

PAR-1 on HEK cells is disarmed by KLK-8. Disarming refers to proteolysis of PAR-1, preventing its ability to activate following the cleavage of a specific peptide bond. The receptor can still be activated by a peptide but cannot be activated by a specific protease (see Dulon, S., et al., Am. J. Respir. Cell Mol. Biol. 28, 339–346, 2003).

The presence of inhibitors in biological fluids might frustrate the measurement of KLKs (Oikonomopoulou, K., et al., Biol. Chem. 391, 381–390, 2010).

KLK-12 undergoes autoactivation, as also seen with blood coagulation factor VII (Pedersen, A.H., et al., Biochemistry 28, 9331–9336, 1989). A factor VII–activating protease (FSAP) that binds hyaluronan has been described (Yamamichi, S., et al., Biochem. Biophys. Res. Commun. 489, 483–488, 2011). It should be noted that there is a recent study suggesting that FSAP does not activate factor VII (Stavenuiter, F., et al., J. Thromb. Haemost. 10, 859–866, 2012). The issue here is that the action of KLKs most likely occurs within the interstitial space, of which hyaluronan is a major component (Section 6.1). Thrombin also activates pro-KLK-12 (Yoon, H., et al., Protein Sci. 17, 1998–2007, 2008).

The CCN family of proteins (CYR61; CTGF; NOV; Chen, C.C. and Lau, L.F., Functions and mechanisms of action of CCN matricellular proteins, Int. J. Biochem. Cell Biol. 41, 771–783, 2009) are matricellular proteins. Matricellular proteins are ECM proteins that may be involved in a variety of processes, including wound healing (Jun, J.I. and Lau, L.F., Taking aim at the extracellular matrix: CCN proteins as emerging therapeutic targets, Nat. Rev. Drug Discov. 10, 945–963, 2011). Cleavage of the CCN membrane proteins may influence the binding of various peptide growth factors.

While there is facile cleavage of HMWK at the carboxyl-terminal end of the kinin sequence, liberation of kinin activity is poor because of poor cleavage at the amino-terminal end of the kinin sequence.

Peptidase activity measured with a FRET peptide substrate (e.g., George, J., et al., Evaluation of an imaging platform during the development of a FRET protease assay, J. Biomol. Screen. 8, 72–80, 2003).

Histatin C and myelin basic proteins were the only “protein” substrates evaluated in this study. The use of a matrix-bound peptide library as substrates for KLK-13 demonstrated cleavage of sequences consistent with a number of other proteins as potential substrates.

HMWK was demonstrated to be a substrate for KLK-13, but there is only limited formation of kinin. See footnote j.

Degradation of several ECM proteins by KLK-13 was evaluated by electrophoresis/Western blot. Rapid degradation of laminin was observed; degradation of collagen I, collagen II, collagen III, and fibronectin was also observed but less striking.

Inhibition of KLK-13 was observed with α₂-antiplasmin, α₂-macroglobulin, α₁-antichymotrypin, protein C inhibitor, PAI-1, antithrombin, kallistatin, and C1-INH.

See Section 6.2 for a more extensive discussion of KLK-B1 in the interstitial space.

Figure 6.1 Activation and actions of plasma and tissue kallikreins. Shown here are the canonical mechanisms for the activation of plasma prekallikrein and tissue prokallikrein and suggested substrates within the interstitial space. The point here is that these two enzymes occur in their precursor or zymogen forms, which require activation for full expression of activity. This requirement for activation provides one of the more significant control mechanisms. Plasma prekallikrein is activated by factor XIIa in plasma, while a physiological activator of tissue prokallikrein remains to be identified. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315374307/eafc876c-1c18-4a14-bc4b-9d9665df6318/content/fig6_1_B.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>