Cyclic GMP-Dependent Regulation of Vascular Tone and Blood Pressure Involves Cysteine-Rich LIM-Only Protein 4 (CRP4).

Natalie Längst,Tanja Zeller,Melanie Cruz Santos,Matthias Sausbier,Robert Lukowski,Olga Schweigert,Julia Adler,Amelie Knauer,Peter Ruth,Felicia Kleusberg

doi:10.3390/ijms22189925

Abstract

The cysteine-rich LIM-only protein 4 (CRP4), a LIM-domain and zinc finger containing adapter protein, has been implicated as a downstream effector of the second messenger 3′,5′-cyclic guanosine monophosphate (cGMP) pathway in multiple cell types, including vascular smooth muscle cells (VSMCs). VSMCs and nitric oxide (NO)-induced cGMP signaling through cGMP-dependent protein kinase type I (cGKI) play fundamental roles in the physiological regulation of vascular tone and arterial blood pressure (BP). However, it remains unclear whether the vasorelaxant actions attributed to the NO/cGMP axis require CRP4. This study uses mice with a targeted deletion of the CRP4 gene (CRP4 KO) to elucidate whether cGMP-elevating agents, which are well known for their vasorelaxant properties, affect vessel tone, and thus, BP through CRP4. Cinaciguat, a NO- and heme-independent activator of the NO-sensitive (soluble) guanylyl cyclase (NO-GC) and NO-releasing agents, relaxed both CRP4-proficient and -deficient aortic ring segments pre-contracted with prostaglandin F2α. However, the magnitude of relaxation was slightly, but significantly, increased in vessels lacking CRP4. Accordingly, CRP4 KO mice presented with hypotonia at baseline, as well as a greater drop in systolic BP in response to the acute administration of cinaciguat, sodium nitroprusside, and carbachol. Mechanistically, loss of CRP4 in VSMCs reduced the Ca2+-sensitivity of the contractile apparatus, possibly involving regulatory proteins, such as myosin phosphatase targeting subunit 1 (MYPT1) and the regulatory light chain of myosin (RLC). In conclusion, the present findings confirm that the adapter protein CRP4 interacts with the NO-GC/cGMP/cGKI pathway in the vasculature. CRP4 seems to be part of a negative feedback loop that eventually fine-tunes the NO-GC/cGMP axis in VSMCs to increase myofilament Ca2+ desensitization and thereby the maximal vasorelaxant effects attained by (selected) cGMP-elevating agents.

Highlights

The vasculature is an integral part of the organism that maintains a proper blood flow, and the supply of the organs with oxygen and nutrients [1,2]
The observed cysteine-rich LIM-only protein 4 (CRP4) expression pattern largely overlapped with IF signals obtained for the cGMP-dependent protein kinase type I (cGKI) protein, which were enriched in the same layer of the vessel wall [67]
Overall levels of cGKI appeared to be lower in the CRP4-deficient aorta (Figure 1A), a finding that was confirmed by Western Blot analyses of protein lysates obtained from whole CRP4 WT and CRP4 KO

Summary

Introduction

The vasculature is an integral part of the organism that maintains a proper blood flow, and the supply of the organs with oxygen and nutrients [1,2]. Defects in vascular biology contribute to hypertension leading to cardiovascular diseases (CVD), such as stroke, peripheral artery disease, myocardial infarction, and heart failure [3,4]. The vascular tone is affected by the contractile status of vascular smooth muscle cells (VSMCs), representing the predominant cell type in the media layer of arteries. As well as impaired vasorelaxation, have been linked to the pathophysiology of hypertension [5,6]. In this context, nitric oxide (NO) plays a key role in the regulation of vascular tone. A decrease in NO bioavailability, due to endothelial dysfunction, and abnormal tension of vessels, is common to multiple diseases, including hypertension [7,8,9]

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