Signal transduction phosphoinositide cascade

MacKenzie, R. S., Melan, M. A., Passey, D. K. Witt-Enderby, P. A. (2002). Dual coupling of MTi and MT2 melatonin receptors to cyclic AMP and phosphoinositide signal transduction cascades and their regulation following melatonin exposure. Biochem. Pharmacol. 63, 587-95. 

Another class of receptors mediate intracellular responses through Ca2+ mobilisation. A specific class of phospholipids, the phosophoinositides play an important role in signal transduction from receptors at the plasma membrane. The cellular responses that use phosphoinositide hydrolysis and Ca2+ mobilisation are diverse, they include general metabolism, secretion, contraction, phototransduction and proliferation. An imbalance of the second messenger system in the proliferation cascade may be responsible for normal cells becoming cancerous. 

A bit further in the transduction cascade, the U.V. activation of caged IP3 electroporated in protoplasts triggered a peak of [Ca " ] and a full PAL activation. All these results point to the involvement, in response to pectic signals, of a phosphoinositide transduction pathway similar to the one existing in animal cells. 

Very recent efforts to further evaluate the functional implications of phosphoinositol signaling in vertebrate chemosensory transduction have led to the discovery that not only the phosphoinositol breakdown pathway catalyzed by phospholipase C, but also membrane phosphoinositols themselves involving phosphoinositide-3-kinase may play a functional role in the transduction process. It was found that 3-phosphoinositides signaling in concert with the canonical phosphoinositide turnover pathway modulate the cyclic nucleotide signaling cascade downstream of the receptor. The data suggest that 3-phosphoinositide, the primary product of PI3K activity, attenuates the cyclic nucleotide-dependent excitation of olfactory neurons (Spehr et al., 2002). 

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