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Differential ERK1/2 Signaling and Hypertrophic Response to Endothelin-1 in Cardiomyocytes from SHR and Wistar-Kyoto Rats: A Potential Target for Combination Therapy of Hypertension

View Article: PubMed Central - PubMed

ABSTRACT

Extracellular signal regulated kinase½ (ERK1/2) signaling is critical to endothelin-1 (ET-1)-induced cardiomyocyte hypertrophy. This study was to investigate ERK1/2 signaling and hypertrophic response to ET-1 stimulation in cardiomyocytes (CMs) from spontaneous hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Primary neonatal SHR and WKY CMs were exposed to ET-1 for up to 24 hrs. Minimal basal ERK1/2 phosphorylation was present in WKY CMs, while a significant baseline ERK1/2 phosphorylation was observed in SHR CMs. ET-1 induced a time- and dose-dependent increase in ERK1/2 phosphorylation in both SHR and WKY CMs. However, ET-1-induced ERK1/2 activation occurred much earlier with significantly higher peak phosphorylation level, and stayed elevated for longer duration in SHR CMs than that in WKY CMs. ET-1-induced hypertrophic response was more prominent in SHR CMs than that in WKY CMs as reflected by increased cell surface area, intracellular actin density, and protein synthesis. Pre-treatment with ERK1/2 phosphorylation inhibitor PD98059 completely prevented ET-1-induced ERK1/2 phosphorylation and increases in cell surface area and protein synthesis in SHR and WKY CMs. The specific PI3 kinase inhibitor LY294002 blocked ET-1-induced Akt and ERK1/2 phosphorylation, and protein synthesis in CMs. These data indicated that ERK1/2 signaling was differentially enhanced in CMs, and was associated with increased cardiac hypertrophic response to ET-1 in SHR. ET-1-induced ERK1/2 activation and cardiac hypertrophy appeared to be mediated via PI3 kinase/Akt signaling in SHR and WKY. The differential ERK1/2 activation in SHR CMs by ET-1 might represent a potential target for combination therapy of hypertension.

No MeSH data available.


ERK1/2 activation was elevated in CMs from SHR at both baseline and in response to ET-1 stimulation. Primary neonatal SHR and WKY CMs were prepared, and exposed to different concentrations of ET-1 for up to 24 hrs. There was minimal basal ERK1/2 phosphorylation in CMs from WKY. In contrast, a significant level of basal ERK1/2 phosphorylation was observed in CMs from SHR. ET-1 induced a time- and dose-dependent increase in ERK1/2 phosphorylation in CMs from both SHR and WKY. However, ET-1-induced ERK1/2 phosphorylation occurred significantly earlier with higher maximal level of activation, and stayed elevated for longer time in CMs from SHR as compared with WKY. A representative Western blotting was shown in the top panel. The relative ERK1/2 phosphorylation in the cells from three independent experiments was summarized in the bottom panel.
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Figure 1: ERK1/2 activation was elevated in CMs from SHR at both baseline and in response to ET-1 stimulation. Primary neonatal SHR and WKY CMs were prepared, and exposed to different concentrations of ET-1 for up to 24 hrs. There was minimal basal ERK1/2 phosphorylation in CMs from WKY. In contrast, a significant level of basal ERK1/2 phosphorylation was observed in CMs from SHR. ET-1 induced a time- and dose-dependent increase in ERK1/2 phosphorylation in CMs from both SHR and WKY. However, ET-1-induced ERK1/2 phosphorylation occurred significantly earlier with higher maximal level of activation, and stayed elevated for longer time in CMs from SHR as compared with WKY. A representative Western blotting was shown in the top panel. The relative ERK1/2 phosphorylation in the cells from three independent experiments was summarized in the bottom panel.

Mentions: There was a low basal level of ERK1/2 phosphorylation in CMs from WKY rats as determined with Western blot (Fig. 1A). When exposed to ET-1, a time- and dose-dependent increase in ERK1/2 phosphorylation was observed in these cells. ERK1/2 phosphorylation reached its maximal level after 10 min incubation with ET-1. Exposure to ET-1 beyond 10 min or ET-1 concentration over 10 nM resulted in a rapid decline in ERK1/2 phosphorylation, and returned to baseline by 60 min (Fig. 1A & B). In contrast, a significant basal ERK1/2 phosphorylation was observed in CMs from SHR. When treated with ET-1, ERK1/2 phosphorylation increased rapidly, and reached its peak level by 5 min of ET-1 exposure. The elevated level of ERK1/2 activation dwindled slowly after 10 min, and remained at a high level after 60 min. The dose-response curve revealed that ERK1/2 activation started to occur at lower ET-1 dose in CMs from SHR as compared with the cells from WKY (Fig. 1B). The maximal level of ET-1-induced ERK1/2 activation in CMs from SHR was almost twice that in CMs from WKY. These results indicated that ET-1 induced an enhanced and sustained ERK1/2 phosphorylation in CMs from SHR compared to the ones from WKY.


Differential ERK1/2 Signaling and Hypertrophic Response to Endothelin-1 in Cardiomyocytes from SHR and Wistar-Kyoto Rats: A Potential Target for Combination Therapy of Hypertension
ERK1/2 activation was elevated in CMs from SHR at both baseline and in response to ET-1 stimulation. Primary neonatal SHR and WKY CMs were prepared, and exposed to different concentrations of ET-1 for up to 24 hrs. There was minimal basal ERK1/2 phosphorylation in CMs from WKY. In contrast, a significant level of basal ERK1/2 phosphorylation was observed in CMs from SHR. ET-1 induced a time- and dose-dependent increase in ERK1/2 phosphorylation in CMs from both SHR and WKY. However, ET-1-induced ERK1/2 phosphorylation occurred significantly earlier with higher maximal level of activation, and stayed elevated for longer time in CMs from SHR as compared with WKY. A representative Western blotting was shown in the top panel. The relative ERK1/2 phosphorylation in the cells from three independent experiments was summarized in the bottom panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4997939&req=5

Figure 1: ERK1/2 activation was elevated in CMs from SHR at both baseline and in response to ET-1 stimulation. Primary neonatal SHR and WKY CMs were prepared, and exposed to different concentrations of ET-1 for up to 24 hrs. There was minimal basal ERK1/2 phosphorylation in CMs from WKY. In contrast, a significant level of basal ERK1/2 phosphorylation was observed in CMs from SHR. ET-1 induced a time- and dose-dependent increase in ERK1/2 phosphorylation in CMs from both SHR and WKY. However, ET-1-induced ERK1/2 phosphorylation occurred significantly earlier with higher maximal level of activation, and stayed elevated for longer time in CMs from SHR as compared with WKY. A representative Western blotting was shown in the top panel. The relative ERK1/2 phosphorylation in the cells from three independent experiments was summarized in the bottom panel.
Mentions: There was a low basal level of ERK1/2 phosphorylation in CMs from WKY rats as determined with Western blot (Fig. 1A). When exposed to ET-1, a time- and dose-dependent increase in ERK1/2 phosphorylation was observed in these cells. ERK1/2 phosphorylation reached its maximal level after 10 min incubation with ET-1. Exposure to ET-1 beyond 10 min or ET-1 concentration over 10 nM resulted in a rapid decline in ERK1/2 phosphorylation, and returned to baseline by 60 min (Fig. 1A & B). In contrast, a significant basal ERK1/2 phosphorylation was observed in CMs from SHR. When treated with ET-1, ERK1/2 phosphorylation increased rapidly, and reached its peak level by 5 min of ET-1 exposure. The elevated level of ERK1/2 activation dwindled slowly after 10 min, and remained at a high level after 60 min. The dose-response curve revealed that ERK1/2 activation started to occur at lower ET-1 dose in CMs from SHR as compared with the cells from WKY (Fig. 1B). The maximal level of ET-1-induced ERK1/2 activation in CMs from SHR was almost twice that in CMs from WKY. These results indicated that ET-1 induced an enhanced and sustained ERK1/2 phosphorylation in CMs from SHR compared to the ones from WKY.

View Article: PubMed Central - PubMed

ABSTRACT

Extracellular signal regulated kinase½ (ERK1/2) signaling is critical to endothelin-1 (ET-1)-induced cardiomyocyte hypertrophy. This study was to investigate ERK1/2 signaling and hypertrophic response to ET-1 stimulation in cardiomyocytes (CMs) from spontaneous hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Primary neonatal SHR and WKY CMs were exposed to ET-1 for up to 24 hrs. Minimal basal ERK1/2 phosphorylation was present in WKY CMs, while a significant baseline ERK1/2 phosphorylation was observed in SHR CMs. ET-1 induced a time- and dose-dependent increase in ERK1/2 phosphorylation in both SHR and WKY CMs. However, ET-1-induced ERK1/2 activation occurred much earlier with significantly higher peak phosphorylation level, and stayed elevated for longer duration in SHR CMs than that in WKY CMs. ET-1-induced hypertrophic response was more prominent in SHR CMs than that in WKY CMs as reflected by increased cell surface area, intracellular actin density, and protein synthesis. Pre-treatment with ERK1/2 phosphorylation inhibitor PD98059 completely prevented ET-1-induced ERK1/2 phosphorylation and increases in cell surface area and protein synthesis in SHR and WKY CMs. The specific PI3 kinase inhibitor LY294002 blocked ET-1-induced Akt and ERK1/2 phosphorylation, and protein synthesis in CMs. These data indicated that ERK1/2 signaling was differentially enhanced in CMs, and was associated with increased cardiac hypertrophic response to ET-1 in SHR. ET-1-induced ERK1/2 activation and cardiac hypertrophy appeared to be mediated via PI3 kinase/Akt signaling in SHR and WKY. The differential ERK1/2 activation in SHR CMs by ET-1 might represent a potential target for combination therapy of hypertension.

No MeSH data available.