Purchase this article with an account.
S.H. Rah, S.J. Lee, D.R. Kim, I.N. Yoon; Characteristics of Cholinergic Receptor Expressed in Human Retinoblastoma . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3421.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: In the present study, we investigated to reveal the role of activation of muscarinic acetylcholine (mACh) receptors in human retinoblastoma Methods: We mearured possible cholinergic signaling in WERI–Rb–1 cells using Ca2+ imaging technique and Western blot analysis. Results: Acetylcholine produced marked and transient [Ca2+]i increases repeatedly in WERI–Rb–1 cells, and atropine (1 µM), a nonselective mAChR inhibitor, greatly suppressed these Ca2+ responses by 97.3±0.8% (n=92). The rapid [Ca2+]i rise by the application of ACh was similar even in the absence of extracellular calcium (n=57). And also, ACh–induced intracellular calcium responses were only attained to 11.5±2.9% (n=58) and 10.3±1.5% (n=62) of peak amplitude of the control after pre–incubation of U–73122 (1 µM), a PLC inhibitor, and thapsigargin (1 µM), an ER membrane Ca2+–ATPase blocker, respectively. 2–APB (20 µM), a membrane–permeable IP3 receptor antagonist, almost blocked the calcium transient. Transcripts encoding all mAChR subtypes (m1∼m5) were detected in WERI–Rb–1 cells. And also we identified M3 and M5 receptor proteins on the Western blot. ACh–induced [Ca2+]i rises were greatly attenuated by pre–treatment of M1 and M3 preferring antagonists. However, [Ca2+]i responses were robust or intact in the presence of M2/M4 preferring antagonists. Conclusions: Muscarinic activation by M3 and M5 receptors can cause IP3–dependent calcium mobilization from the internal stores of the undifferentiated retinoblastoma cells, which may play important roles in cell proliferation, differentiation, and cell death.
This PDF is available to Subscribers Only