The PKG1 specific phosphorylation substrate cysteine-rich protein 2 knockout decreases blood pressure and intimal hyperplasia

Introduction The cysteine-rich protein 2 has previously been suggested as a novel target of PKG1. Cysteine-rich proteins (CRP) are evolutionarily conserved proteins that define a subset of zinc-binding LIM domain proteins. This family of LIM domain proteins originally included three members (CRP1, CRP2/SLIM, CRP3/MLP). Previously, a new member of the CRP family was identified through a yeast two hybrid screen using PKG1 as bait. This protein was initially named CRP2. Subsequently, based on structural and sequence similarities, and because it is the product of a distinct gene and not an ortholog of CRP2/smLIM this new CRP2 was grouped into the CRP1, CRP2/SLIM, CRP3/MLP subset of LIM domain proteins and is also referred to as CRP4. CRP4 is expressed in laminas I and II of the mouse spinal cord and is colocalized with PKG1 and the dorsal root ganglion (DRG) marker proteins calcitonin gene-related peptide, isolectin B4 and peripherin. CRP4 is phosphorylated in a cGMP-dependent manner, and its expression increases in the spinal cord and in DRGs after noxious stimulation of a hindpaw. CRP4-/mice show increased nociceptive behavior in models of inflammatory hyperalgesia compared to wild-type mice. Intrathecal administration of cGMP analogs increases the nociceptive behavior in wild-type but not in CRP4-/mice, indicating that the presence of CRP4 is important for cGMP-mediated nociception. CRP4 has been suggested as a new effector of PKG1-mediated spinal nociceptive processing and point to an inhibitory role of CRP2 in the generation of inflammatory pain.