In addition to their role in protein degradation and digestion, proteases can also function as hormone-like signaling molecules that regulate vital patho-physiological processes, including inflammation, hemostasis, pain, and repair mechanisms. Certain proteases can signal to cells by cleaving protease-activated receptors (PARs), a family of four G protein-coupled receptors. PARs are expressed by almost all cell types, control important physiological and disease-relevant processes, and are an emerging therapeutic target for major diseases. Most information about PAR activation and function derives from studies of a few proteases, for example thrombin in the case of PAR1, PAR3, and PAR4, and trypsin in the case of PAR2 and PAR4. These proteases cleave PARs at established sites with the extracellular N-terminal domains, and expose tethered ligands that stabilize conformations of the cleaved receptors that activate the canonical pathways of G protein- and/or β-arrestin-dependent signaling. However, a growing number of proteases have been identified that cleave PARs at divergent sites to activate distinct patterns of receptor signaling and trafficking. The capacity of these proteases to trigger distinct signaling pathways is referred to as biased signaling, and can lead to unique patho-physiological outcomes. Given that a different repertoire of proteases are activated in various patho-physiological conditions that may activate PARs by different mechanisms, signaling bias may account for the divergent actions of proteases and PARs. Moreover, therapies that target disease-relevant biased signaling pathways may be more effective and selective approaches for the treatment of protease- and PAR-driven diseases. Thus, rather than mediating the actions of a few proteases, PARs may integrate the biological actions of a wide spectrum of proteases in different patho-physiological conditions.

Background: Proteases trigger inflammation and pain by cleaving protease-activated receptors (PARs) at defined sites. Results: Cathepsin S (Cat-S) cleaved PAR 2 at a unique site E 56 2T 57 , leading to G␣s-mediated cAMP accumulation and TRPV4-dependent inflammation and pain. Conclusion: Cat-S is a biased agonist of PAR 2 -and TRPV4-dependent inflammation and pain. Significance: PARs integrate responses to diverse proteases.

Background: Circulating natriuretic peptide concentrations are increased in cats with myocardial dysfunction. Hypothesis: Serum N-terminal fragment of proatrial natriuretic peptide (NT-proANP) and NT-probrain natriuretic peptide (proBNP) concentrations may predict the presence of heart disease (HD) and congestive heart failure (CHF). A positive relationship is also predicted among natriuretic peptide (NP) concentrations, a noninvasive estimate of left ventricular filling pressure (E/E a ), and an echocardiographic measure of left atrial (LA) size (LA/aortic diameter [Ao]).Methods: Serum NP concentrations were measured in 28 healthy control and 50 study cats using sandwich enzyme immunoassays. The study group comprised cats, with HD but no CHF (HD À CHF, n 5 17) and cats with CHF (HD 1 CHF, n 5 33). The relationship among NP concentrations, LA size, and E/E a was examined. The ability of NP to distinguish control from study cats, and HD À CHF from HD 1 CHF cats, was explored using receiver operator curve analysis.Results: NP concentrations were significantly lower in control than in study cats (P 5 .0001). The NT-proBNP concentrations were positively correlated with LA/Ao ratio (r 5 0.34; P 5 .02) and with E/E a ratio (r 5 0.68; P o .05). An NT-proBNP concentration of 49 fmol/mL gave a sensitivity and specificity of 100 and 89.3%, respectively, for correctly distinguishing 96.2% of control from study cats. Pairwise comparisons of the areas under the curve identified a statistically significant difference (P 5 .011) between NT-proANP and NT-proBNP to distinguish control from study cats. NT-proANP and NT-proBNP concentrations were significantly higher in HD 1 CHF cats than in HD À CHF cats (P 5 .0023 and .0001, respectively).Conclusions: Serum concentrations of NT-proANP and particularly NT-proBNP were different in healthy control cats, asymptomatic cats with HD, and cats with CHF, suggesting that measurement of NP concentrations may prove clinically useful as an initial screening test for cats with suspected cardiac disease.

PAGE 27220:The N-terminal amino acid sequence of PAR2 in Fig. 1A is not correct because a repeat of an amino acid sequence (11-16, GAAILL) was accidentally inserted into positions 17-22. The correct sequence is shown in the revised Fig. 1A. This correction does not affect the results or conclusions of this work.

A BSTRACTAntagonists of the kappa opioid receptor were initially investigated as pharmacological tools that would reverse the effects of kappa opioid receptor agonists. In the years following the discovery of the fi rst selective kappa opioid antagonists, much information about their chemistry and pharmacology has been elicited and their potential therapeutic uses have been investigated. The review presents the current chemistry, ligand-based structure activity relationships, and pharmacology of the known nonpeptidic selective kappa opioid receptor antagonists. This manuscript endeavors to provide the reader with a useful reference of the investigations made to defi ne the structure-activity relationships and pharmacology of selective kappa opioid receptor antagonists and their potential uses as pharmacological tools and as therapeutic agents in the treatment of disease states.