作者: Stott, Jennifer B. ; Homer, Natalie Z. M. ; Isakson, Brant E. ; Baldwin, Samuel N. ; Albert, Anthony P. ; Greenwood, Iain A. ; Barrese, Vincenzo ; Andrew, Ruth ; Forrester, Elizabeth A.

Background and PurposeKcnq‐encoded KV7 channels (termed KV7.1–5) regulate vascular smooth muscle cell (VSMC) contractility at rest and as targets of receptor‐mediated responses. However, the current data are mostly derived from males. Considering the known effects of sex, the oestrous cycle and sex hormones on vascular reactivity, here we have characterised the molecular and functional properties of KV7 channels from renal and mesenteric arteries from female Wistar rats separated into di‐oestrus and met‐oestrus (F‐D/M) and pro‐oestrus and oestrus (F‐P/E).Experimental ApproachRT‐qPCR, immunocytochemistry, proximity ligation assay and wire myography were performed in renal and mesenteric arteries. Circulating sex hormone concentrations were determined by liquid chromatography–tandem mass spectrometry. Whole‐cell electrophysiology was undertaken on cells expressing KV7.4 channels in association with G‐protein‐coupled oestrogen receptor 1 (GPER1).Key ResultsThe KV7.2–5 activators S‐1 and ML213 and the pan‐KV7 inhibitor linopirdine were more effective in arteries from F‐D/M compared with F‐P/E animals. In VSMCs isolated from F‐P/E rats, exploratory evidence indicates reduced membrane abundance of KV7.4 but not KV7.1, KV7.5 and Kcne4 when compared with cells from F‐D/M. Plasma oestradiol was higher in F‐P/E compared with F‐D/M, and progesterone showed the converse pattern. Oestradiol/GPER1 agonist G‐1 diminished KV7.4 encoded currents and ML213 relaxations and reduced the membrane abundance of KV7.4 and interaction between KV7.4 and heat shock protein 90 (HSP90), in arteries from F‐D/M but not F‐P/E.Conclusions and ImplicationsGPER1 signalling decreased KV7.4 membrane abundance in conjunction with diminished interaction with HSP90, giving rise to a ‘pro‐contractile state’.

2018-06-01·Hypertension1区 · 医学

Angiotensin II Promotes K _V 7.4 Channels Degradation Through Reduced Interaction With HSP90 (Heat Shock Protein 90)

1区 · 医学

Article

作者: Greenwood, Iain A. ; Barrese, Vincenzo ; Jepps, Thomas A. ; Hobbs, Adrian J. ; Figueiredo, Hericka B. ; McNeish, Alister J. ; Aubdool, Aisah A. ; Stott, Jennifer B.

Voltage-gated K v 7.4 channels have been implicated in vascular smooth muscle cells’ activity because they modulate basal arterial contractility, mediate responses to endogenous vasorelaxants, and are downregulated in several arterial beds in different models of hypertension. Angiotensin II (Ang II) is a key player in hypertension that affects the expression of several classes of ion channels. In this study, we evaluated the effects of Ang II on the expression and function of vascular K v 7.4. Western blot and quantitative polymerase chain reaction revealed that in whole rat mesenteric artery, Ang II incubation for 1 to 7 hours decreased K v 7.4 protein expression without reducing transcript levels. Moreover, Ang II decreased XE991 (K v 7)–sensitive currents and attenuated membrane potential hyperpolarization and relaxation induced by the K v 7 activator ML213. Ang II also reduced K v 7.4 staining at the plasma membrane of vascular smooth muscle cells. Proteasome inhibition with MG132 prevented Ang II–induced decrease of K v 7.4 levels and counteracted the functional impairment of ML213-induced relaxation in myography experiments. Proximity ligation assays showed that Ang II impaired the interaction of K v 7.4 with the molecular chaperone HSP90 (heat shock protein 90), enhanced the interaction of K v 7.4 with the E3 ubiquitin ligase CHIP (C terminus of Hsp70-interacting protein), and increased K v 7.4 ubiquitination. Similar alterations were found in mesenteric vascular smooth muscle cells isolated from Ang II–infused mice. The effect of Ang II was emulated by 17-AAG (17-demethoxy-17-(2-propenylamino) geldanamycin) that inhibits HSP90 interactions with client proteins. These results show that Ang II downregulates K v 7.4 by altering protein stability through a decrease of its interaction with HSP90. This leads to the recruitment of CHIP and K v 7.4 ubiquitination and degradation via the proteasome.

Journal of Pain Research

Kv7 Channel Activators Flupirtine and ML213 Alleviate Neuropathic Pain Behavior in the Streptozotocin Rat Model of Diabetic Neuropathy

Article

作者: Djouhri, Laiche ; Zeidan, Asad ; Agouni, Abdelali ; Ahmed, Ashraf Ibrahim ; Mustafa, Ayman ; Al-Nuaimi, Salma

Background & ObjectiveChronic peripheral neuropathic pain (PNP) is a debilitating condition that is associated with many types of injury/diseases, including diabetes mellitus. Patients with longstanding diabetes develop diabetic PNP (DPNP), which is resilient to currently available drugs. The underlying molecular mechanisms of DPNP are still illusive, but K_v7 channels that have been implicated in the pathogenesis of various types of chronic pain are likely to be involved. Indeed, using the streptozotocin (STZ) rat model of DPNP, we have previously shown that K_v7 activation with their non-selective activator retigabine attenuated neuropathic pain behavior suggesting that these channels are implicated in DPNP pathogenesis. Here, we evaluated, in the same STZ model, whether the more potent and more selective K_v7 channel openers flupirtine and ML213 attenuate STZ-induced pain hypersensitivity.MethodsMale Sprague Dawley rats (250-300 g) were used. The STZ model involved a single injection of STZ (60 mg/kg, i.p.). Behavioral testing for mechanical and heat pain sensitivity was performed using a dynamic plantar aesthesiometer and Hargreaves analgesiometer, respectively.ResultsSTZ rats exhibited behavioral signs of mechanical and heat hypersensitivity as indicated by significant decreases in the mean paw withdrawal threshold (PWT) and mean paw withdrawal latency (PWL), respectively, at 35 days post-STZ treatment. Single injections of flupirtine (10 mg/kg, i.p.) and ML213 (5 mg/kg, i.p.) to STZ rats (35-days after STZ treatment) caused significant increases in the mean PWT, but not PWL, indicating attenuation of mechanical, but not heat hypersensitivity. Both flupirtine and ML213 were as effective as the positive control gabapentin (10/kg, i.p.), and their anti-allodynic effects were prevented by the K_v7 channel-specific blocker XE991 (3 mg/kg, i.p.).ConclusionThe findings suggest that K_v7 channels are involved in the mechanisms of mechanical but not heat hypersensitivity associated with DPNP, and that their activation may prove to be effective in alleviating DPNP symptoms.

100 项与 ML213 相关的药物交易

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