If you recall the post #2, you will remember that communication between different cells of the body occur via signals that are released and captured by antennae docked on the top of the cell dome (the cell membrane). Initially I said that these signals are then translated into effects as a result of further talk within the cells themselves. So the consecutive transmission of signals (through ligands, remember) coming from the outside to the internal side of the cells is termed “signal transduction” or, more friendly, “signaling cascade”, as the information goes in a sort of “top to bottom” approach, falling from the top of the cell dome towards the grounds. Like a secret whisper that is transmitted from neighbour to neighbour, our signal is passed along by intermediators that we call generally “second messengers”. Biochemically we define a second messenger as a molecule that increases upon a stimulus above a steady state quantity for a short time, to further return to its initial concentration when the signal has been transmitted (imagine the waves generated by the movements of the oceans: each wave might well represent a signal transduction from the horizon to the shoreline). Thus we now understand that this fluctuation is the core of the transmitting system…and guess what, in the ancient Latin language a fluctus is indeed a wave!
No need to mention that we (islet biologists) are very interested in understanding what waves are generated upon the binding of a ligand to a receptor as they are the intracellular intermediators of the results we observe in terms of insulin secretion. Examples of second messengers involved in the release of the insulin granules (please allow me to explain this terminology successively) are represented by small ions (like calcium) as well as newly synthesised molecules such as ATP (the cellular currency) and one of its derivatives, cyclic AMP. Other players are generated from the enzymatic conversion of fats that are components of the cell dome. Nevertheless, it should not surprise you if we actually g monitor their fluctuation and their generation within the islets of Langerhans, and in particular the beta cells.
I think this post has become heavy enough for this round…so, keep following me in my future publishing to discover how we perform this particular kind of magic! (and indeed there’s going to be some colourful pyrotechnic arts too!)