Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tuebingen, 72076 Tuebingen, Germany.
Cardiovascular Systems Medicine and Molecular Translation, University Center of Cardiovascular Science, University Heart & Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.
Int J Mol Sci. 2021 Sep 14;22(18):9925. doi: 10.3390/ijms22189925.
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 Ca-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 Ca desensitization and thereby the maximal vasorelaxant effects attained by (selected) cGMP-elevating agents.
富含半胱氨酸的 LIM 仅蛋白 4（CRP4）是一种 LIM 结构域和锌指结合衔接蛋白，作为第二信使 3'，5'-环鸟苷单磷酸（cGMP）途径在多种细胞类型中的下游效应子，包括血管平滑肌细胞（VSMCs）。VSMCs 和一氧化氮（NO）诱导的 cGMP 信号通过 cGMP 依赖性蛋白激酶 I 型（cGKI）发挥基本作用，调节血管张力和动脉血压（BP）的生理调节。然而，尚不清楚归因于 NO/cGMP 轴的血管舒张作用是否需要 CRP4。本研究使用靶向 CRP4 基因缺失的小鼠（CRP4 KO）来阐明 cGMP 升高剂是否通过 CRP4 影响血管张力，从而影响血管紧张度和 BP。西那卡塞是一种非 NO 和血红素依赖性的 NO 敏感（可溶性）鸟苷酸环化酶（NO-GC）激活剂和 NO 释放剂，可松弛前列腺素 F2α 预收缩的 CRP4 阳性和阴性的主动脉环段。然而，在缺乏 CRP4 的血管中，松弛的幅度略有但显著增加。因此，CRP4 KO 小鼠在基础状态下表现出低张力，并且在急性给予西那卡塞、硝普钠和卡巴胆碱时，收缩压下降幅度更大。从机制上讲，VSMCs 中 CRP4 的缺失降低了收缩装置的 Ca 敏感性，这可能涉及调节蛋白，如肌球蛋白磷酸酶靶向亚基 1（MYPT1）和肌球蛋白调节轻链（RLC）。总之，本研究结果证实，衔接蛋白 CRP4 与血管中的 NO-GC/cGMP/cGKI 途径相互作用。CRP4 似乎是一种负反馈回路的一部分，该回路最终可微调 VSMCs 中的 NO-GC/cGMP 轴，以增加肌球蛋白丝 Ca 脱敏，从而增加（选定的）cGMP 升高剂达到的最大血管舒张作用。
