| First Author | Sinha RK | Year | 2018 |
| Journal | Blood | Volume | 131 |
| Issue | 11 | Pages | 1163-1171 |
| PubMed ID | 29343482 | Mgi Jnum | J:261560 |
| Mgi Id | MGI:6155834 | Doi | 10.1182/blood-2017-10-810895 |
| Citation | Sinha RK, et al. (2018) PAR1 biased signaling is required for activated protein C in vivo benefits in sepsis and stroke. Blood 131(11):1163-1171 |
| abstractText | Activated protein C (APC) cleaves protease-activated receptor 1 (PAR1) in vitro at R46 to initiate beneficial cell signaling; however, thrombin and APC can cleave at R41. To elucidate PAR1-dependent aspects of the pharmacologic in vivo mechanisms of APC, we generated C57BL/6 mouse strains carrying QQ41 or QQ46 point mutations in PAR1 (F2r gene). Using these strains, we determined whether or not recombinant murine signaling-selective APC mutants would reduce septic death or provide neuroprotection against ischemic stroke when mice carried PAR1-homozygous mutations that prevent cleavage at either R41 or R46. Intercrossing PAR1(+)/R46Q mice generated expected numbers of PAR1(+/+), PAR1(+)/R46Q, and R46Q/R46Q offspring whereas intercrossing PAR1(+)/R41Q mice gave decreased R41Q/R41Q homozygotes (resembling intercrossing PAR1(+)/PAR1-knockout mice). QQ41-PAR1 and QQ46-PAR1 brain endothelial cells showed the predicted retention or loss of cellular responses to thrombin receptor-activating peptide, thrombin, or APC for each PAR1 mutation. In sepsis studies, exogenous APC reduced mortality from 50% to 10% in Escherichia coli-induced pneumonia for wild-type (Wt) PAR1 and QQ41-PAR1 mice (P < .01) but had no benefit for QQ46-PAR1 mice. In transient distal middle cerebral artery occlusion stroke studies, exogenous APC significantly reduced infarct size, edema, and neuronal apoptosis for Wt mice and QQ41-PAR1 mice but had no detectable benefits for mice carrying QQ46-PAR1. In functional studies of forelimb-asymmetry and foot-fault tests at 24 hours after stroke induction, signaling-selective APC was beneficial for Wt and QQ41-PAR1 mice but not QQ46-PAR1 mice. These results support the concept that APC-induced, PAR1-dependent biased signaling following R46 cleavage is central to the in vivo benefits of APC. |
