Relative expression of protease-activated receptor 1 (PAR-1) mRNA in rat Schwann cells remains stable following PAR-1 activation

Abstract

Protease-activated Receptor-1 (PAR-1) is a G protein-coupled receptor activated by the serine protease thrombin. Neurons and glial cells express PAR-1, and dysregulation of thrombin and/or PAR-1 is implicated in inflammatory disorders, neurodegenerative diseases, and spinal cord injury. We confirmed PAR-1 localization on rat Schwann cells using immunocytochemistry and confirmed gene expression with RT- qPCR (reverse transcription quantitative real-time PCR). We hypothesized that PAR-1 activation may involve a feedback mechanism, by which initial activation modulates PAR-1 mRNA levels, protein expression, and therefore future sensitivity of the cell to PAR-1 activation. Schwann cells were treated with 100 nM of the synthetic peptide SFLLRNP to activate PAR-1, and RT- qPCR was conducted for PAR-1 mRNA following incubations of 0, 4, 8, or 12 h. We demonstrate that PAR-1 mRNA levels are stable following PAR-1 activation in Schwann cells, indicating that other mechanisms may be responsible for the PAR-1 mRNA dysregulation observed in injury and disease. Our results also suggest that, in Schwann cells, there is no de novo synthesis of PAR-1 to replace internalized receptors in the period soon after (∼30 min after) extended periods of activation. Understanding the mechanisms underlying PAR-1 expression is essential since disruption of PAR-1 signaling in the nervous system can contribute to disease states.