Novel Biological Substrates of Human Kallikrein 7 Identified through Degradomics

Abstract

Background:The physiological substrates of most kallikreins remain unknown. Results: Our degradomics approach combined with sequence analysis identified a number of novel substrates for KLK7. Conclusion: Proteolytic cleavage of midkine, CYR61, and tenascin-C govern the pathophysiological roles of KLK7. Significance: Our data provide further insights into the physiological roles of KLK7.

An unexpected switch in peptide binding mode: from simulation to substrate specificity

“…This data might be slightly biased by the cleavage of the predominantly tryptic propeptide substrates from the studies on the KLK activation cascades, with the consensus sequence R-IVGG (Yoon et al, 2007, 2009). Cleavage data of fluorogenic peptides confirms the previously reported high preference in P1 for Tyr over Phe, while Arg occurs in less than 10% of cleavages and Lys or Ala not at all, whereas the specificity of the other subsites on the non-prime and prime side seems relatively low (Yu et al, 2015). Cleavage entropies are a measure for the general specificity of a subsite and their combination (Fuchs et al, 2013).…”

“…Beyond the S1 pocket, specificity of KLK7 has been characterized for the non-prime region of the binding site that shows non-specific binding especially in case of S3 and S4 (Debela et al, 2006). Recently, proteomics and FRET-based approaches have been used to characterize the substrate specificity of KLK7 also in the prime side region (Oliveira et al, 2015; Yu, Prassas, Dimitromanolakis, & Diamandis, 2015). In addition to static binding site properties flexibility of adjacent loop regions, especially the 99-loop, has been described as crucial for enzymatic function of KLKs (Skala et al, 2014).…”

Ablation of kallikrein 7 (KLK7) in adipose tissue ameliorates metabolic consequences of high fat diet-induced obesity by counteracting adipose tissue inflammation in vivo

“…Yet, there is a growing number of potential peptide and protein targets that may suggest possible pathways affected by KLKs in general and KLK7 specifically (reviewed in [ 48 ]). With respect to the observed anti-inflammatory phenotype in AT of AT Klk7 − / − mice, various pro-inflammatory cytokines (IL-1β [ 49 ]), adipokines (chemerin [ 37 ], midkine [ 50 ]) or other proteins (TNC [ 50 ]) or proteases (MMP9 [ 51 ]) may be relevant and have been previously shown to be substrates of KLK7. IL-1β represents an insulin resistance-promoting adipokine with strong pro-inflammatory properties and AT expression is upregulated in HFD-induced obesity and insulin-resistant mouse models [ 52 ].…”

Integration of Two In-depth Quantitative Proteomics Approaches Determines the Kallikrein-related Peptidase 7 (KLK7) Degradome in Ovarian Cancer Cell Secretome

“…Notably, established KLK7 substrates, fibronectin 1 (FN1), desmoglein 2 (DSG2, (33) (Table II, supplemental Table S2). Notably, two established KLK7 substrates, MMP2 (34) and IGFBP3 (35) were cleaved in SKOV-3 cell CM, in the TAILS approach. Moreover, the two established substrates of KLK7 that were identified in the qPROTOMAP approach, DSG2 and FN1, were not detected to be cleaved by KLK7 in the TAILS approach where a 4-fold less concentration (1:200 of active site-titrated KLK7: CM w/w) of KLK7 was used compared with the qPROTOMAP approach (1:50 of active site-titrated KLK7: CM w/w).…”