Protease‐activated receptor subtype expression in developing eye and adult retina of the rat after optic nerve crush

Abstract

Protease-activated receptors (PARs), 7-transmembrane domain G protein-coupled receptors, are involved in tissue degeneration and repair upon injury. We demonstrate the expression of all four PAR subtypes in the postnatal eye and in retina of the adult rat by reverse transcription-polymerase chain reaction (RT-PCR). PAR-1 is regulated developmentally in the eye, with a decrease from P1, P9, to P16, whereas levels for PAR-2, PAR-3, and PAR-4 remain unchanged throughout. In the retina of the adult rat, PAR-1 is highly expressed, whereas PAR-2 and PAR-3 are moderately expressed, compared to low PAR-4 expression. To elucidate possible roles of PARs after trauma, we carried out semiquantitative RT-PCR analysis of expression of all 4 PAR subtypes, beginning 6 hr after partial optic nerve crush (ONC) in the adult rat until 3 weeks after the mild trauma. Levels of PAR mRNA for all four subtypes were upregulated as early as 6 hr after unilateral ONC, except PAR-3, which showed a delayed upregulation. PAR-1, PAR-3, and PAR-4 mRNA levels returned to almost basal levels at 3 weeks post-crush, whereas PAR-2 mRNA level was still high by the end of 3 weeks after crush. Although the lesion was unilateral, PAR mRNA expression in the contralateral, uninjured side was affected to levels almost comparable to those in the injured side. Previous studies have shown an increase in thrombin levels at the site of injury, retinal ganglion cell degeneration by necrosis and apoptosis, and PAR activation as consequences of nerve crush. PAR upregulation because of nerve crush in the mild trauma model could act as an effector of early cell death. Eventual return of receptor mRNA to basal levels is consistent with neuroprotection.

Contributions of Protease-Activated Receptors PAR1 and PAR4 to Thrombin-Induced GPIIbIIIa Activation in Human Platelets

“…Finally, reversibility is a requisite for developing positron emission tomography tracers. PAR4 expression has been demonstrated to be dynamic and reflective of various pathologic conditions (Rohatgi et al, 2003;Henrich-Noack et al, 2006;Dabek et al, 2009;Zhang et al, 2014a,b;Yu et al, 2015) and, therefore, has the potential for developing into a biomarker. The last example presented in this article (example 6, VU0806526) represents a route forward to developing additional specific PAR4 antagonists that can be fully outcompeted by higher concentrations of thrombin.…”

Thrombin enhances the barrier function of rat microvascular endothelium in a PAR-1-dependent manner

“…One microgram of total RNA and the Qiagen OneStep RT-PCR kit were used for the RT-PCR reactions with specific primers. The primers used for these reactions are shown in Table 1 (38). PAR-1 and PAR-3 were amplified with 30 cycles (94°C for 30 s, 50°C for 30 s, 72°C for 60 s), PAR-2 was amplified with 30 cycles (94°C for 30 s, 54°C for 30 s, 72°C for 60 s), and PAR-4 was amplified with 30 cycles (94°C for 30 s, 59°C for 30 s, 72°C for 30 s).…”

“…To begin characterizing the vascular segment-specific responses of thrombin on pulmonary endothelial cells, we first compared the effect of rat thrombin (Sigma, St. Louis, MO) on the barrier function of rat PMVEC and PAEC in vitro ( The primers listed are as described by Rohatgi et al (38). The run conditions are provided in MATERIALS AND METHODS.…”

Oroxylin A promotes retinal ganglion cell survival in a rat optic nerve crush model

“…The optic nerve crush model can imitate the optic nerve damage and is commonly used to study neurodegenerative process in the optic nerve and retina and to screen the potential neuroprotective reagents for acute optic neuropathies. Optic nerve crush constitute a primary axonal injury which directly disrupts the axolemma, resulting in sodium and calcium influx and the activation of protease progressing to neuronal death [9–12]. Crush injury induced macrophage and microglia accumulation at the site of the insult.…”