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A.K. Samadi, R.J. Cenedella; Rapid Activation of ERK1/2 Mitogen-Activated Protein Kinase by Corticosterone in Bovine Lens Epithelial Cells . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3505.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Chronic glucocorticoid treatment will induce cataract in humans. Previous work in this laboratory indicated rapid Ca2+ influx in bovine lens epithelial cells induced by progesterone (Samadi A, et al., Pflugers Arch – Eur J Physiol (2002) 444:700-709). We are exploring the possibility that corticosterone can induce ERK1/2 MAP kinase signal transduction pathway. Methods: Bovine lens epithelial cells (BLEC) treated with varying concentration (10-11 – 10-7 M) of corticosterone. In addition, BLEC were treated with 100nM of corticosterone for varying amount of time. Activation of ERK1/2 was assayed using western blotting with specific antibodies. Blocking experiments using PD98059 and UO126 (specific inhibitors of MEK1 and ERK1/2 activation) were used to assess the role of corticosterone activation of ERK1/2 MAP kinase signaling. Results: Corticosterone can induce a rapid activation of ERK1/2 MAP kinase in BLEC. Similar results were obtained with progesterone, aldosterone and cortisol at 100nM concentrations. The maximal activation of ERK1/2 by corticosterone was at 10-9 M. Corticosterone induced the activation of ERK1/2 in 10 mins of culture, followed by decrease which persisted for 60 mins. Corticosterone induced activated ERK1/2 MAP kinase was inhibited in the presence of PD98059 and UO126. This indicates that corticosterone activates the ERK1/2 MAP kinase cascade. Conclusions: Corticosterone induces ERK1/2 MAP kinase activation in lens cells in dose response manner. The effect of corticosterone on lens may be directed through MP kinase signaling. Corticosterone might rapidly act via putative membrane receptor independent of cellular receptor. Since other steroid hormone induce a rapid ERK1/2 MAP kinase activation in lens cells, they may induce cellular activation through different membrane proteins.
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