(228) Polo-like Kinase 1 Modulates Vascular and Cavernosal Reactivity in Wild Type Mice

Abstract

Abstract Introduction Polo-like kinase 1 (Plk1) is a Ser/Thr protein kinase that plays a role in cell cycle regulation and is required for arterial structure organization. It has also been shown to be required for RhoA activation and vasoconstriction. We aimed to investigate whether Plk1 is involved in erectile dysfunction playing a role in the contraction of the pudendal artery (PA) and corpus cavernosum (CC). Objective We aimed to test the hypothesis that agonist-mediated contraction is dependent on activation of Plk1 in the PA and CC. Methods Male wild type mice were used in this study. The PA and the CC were isolated and mounted in a wire- and strip- myograph, respectively. In the PA, contractions were obtained by concentration-response curves to phenylephrine (PE), serotonin (5-HT), thromboxane A2 analogue U46619 and angiotensin II (Ang-II). In the CC, we performed concentration-response curves to PE, 5-HT and electrical field stimulation (EFS), and relaxation was tested by EFS as well. Concentration-response curve to the same agonist was repeated after incubation with Plk1 inhibitor Volasertib (100 nM). Contractions in the presence of Volasertib were calculated as percentage of the maximal contraction evoked by its respective agonist in control conditions, which was considered 100%. Expression of Plk1 was evaluated by western blot using a pool of resistance arteries in control conditions and after incubation with Ang-II, with or without the Plk1 inhibitor Volasertib. Curves to Ang-II were also repeated in the absence of any inhibitor to rule out tachyphylaxis to the peptide in the second curve. Relaxation is given as % of contraction induced by PE. Paired Student’s t-test was used for data analysis. Data are expressed as mean ± S.E.M of 3-5 mice. Results In the PA, Volasertib treatment did not affect the contraction induced by PE, 5-HT and U46619. On the other hand, the contraction induced by Ang-II was virtually abolished by Volasertib (100 nM) reaching a maximal response of only EMAX: 3.86 ± 0.97%. In the CC, the contractions induced by PE, 5-HT and electrical field stimulation were not affected by Plk1 inhibition (95 ± 6%, 99 ± 5% and 102 ± 0.4%, respectively). On the other hand, the relaxation induced by EFS 16 Hz (73 ± 3%) was significantly facilitated by Volasertib treatment (84 ± 2%). Protein expression of total Plk1 was not affected in the pool of arteries treated with Ang-II (100 nM) and/or Volasertib (100 nM). However, Ang-II incubation increased the phosphorylation of PLK1, which was inhibited when the arteries were incubated with Volasertib. Conclusions Our findings are the first to demonstrate that Plk1 plays a role in Ang-II-induced contraction of the PA and Volasertib treatment can improve relaxation in the CC of mice. More studies are necessary to elucidate the process of Plk1 activation and whether Plk1 plays a role in the development of sexual dysfunction in pathological conditions such as diabetes. Disclosure No