What is cellular communication and why is it critical to life? What does the ability to communicate imply? What happens when there is a failure to communicate in the cell? Or between an organism’s different cells? Or systems of cells? Or between organisms? These are some of the questions we will attempt to discuss.
First, what is cellular communication and how does it occur? As the term implies, cellular communication is the ability of cellular components, such as the endoplasmic reticulum, ribosomes, vesicles, tRNA, rRNA, mRNA, spindles, tubules, Golgi apparatus and so on, to talk to and understand each other. By using a simplistic analogy such as “talking”, we mean to say these structures carry on them or around them specific signaling molecules (proteins) that are designed as lock-and-key, in which the signaling molecule has a certain shape and configuration. The recipient and intended target of this protein has a matching configuration. This enables the recipient organelle to latch onto the intended incoming structure and receive the contents, or message. Oftentimes the signal itself will be an ion, such as calcium, sodium or potassium, which passes its electron down and continues the propagation of the signal into a cascade effect. Other times the signal is the energy molecule ATP, which also powers the signaling protein on its way to the recipient site. Once there, the ATP passes one phosphate to the recipient molecule and starts a cascade effect, powering the reaction all the way through until a “STOP” signal (another protein!) is received.
This method of cascading reactions powers many of the metabolic pathways in living systems. It allows a signal to be sent efficiently, without requiring large amounts of ATP, since it is faster and easier for the first ATP to simply pass one phosphate to a nearby waiting ADP molecule, which will continue the domino effect. This example of communication is performed at the speed of thought, itself another type of cellular communication. In effect, I think of the next thing I want to say, transfer that thought by electrical synapse down my spine to my arms and to each individual finger, to press on the appropriate letter at the appropriate time, by individually powering each finger’s retractor muscle with calcium ions, passed through special protein pores, that is then sent to and fires on each muscle fiber. The staggering complexity of it should not be quickly dismissed. This typing of the keyboard is not even an important task as far as keeping me alive. Think of the countless signals my heart receives, on time every time, to keep the muscle fibers of my heart contracting in the proper sequence through the four chambers of the heart, keeping my blood circulating throughout my body, even while I sleep. Such efficiency and exactness is humbling to contemplate.
Why is cellular communication critical to life? Simply because if the signaling proteins that escort the various transport vesicles throughout my body at any given time become distorted due to mutations, unbeknown to me, or due to toxic compounds, such as alcohol or other substances, complications arise immediately. No mutation has ever been shown to be beneficial to a protein that is already completely functional. In fact, once a protein has been properly assembled and folded, it cannot be improved upon. I say properly assembled and folded, because it is in these crucial steps that mutations almost always cause problems. A mutated hemoglobin protein causes insufficient oxygen carrying capacity, leading to anemia, for example. There are many others. The take-home message is that the body’s various systems require constant communication to and from the processing centers in the brain and spine. A misfolded chaperone protein, or leaky pore protein, or misshaped receptor protein or demyelinated axon can cause things to get out of control very quickly.
Another example of the importance of communication is found in the immune system. Recognizing self from non-self is no easy task, otherwise we would never get sick. The fact that most of us are not sick all the time is a testament to the efficiency and tenacity of our immune responses, whether they deal with histamines, viruses, or bacteria. The ability of the lymphatic system to be aware of invading outsiders and to dispatch the appropriate response team to the appropriate location depends completely on hundreds of thousands of signaling proteins, each one specialized according to its receptor. To entertain even for a moment that all of these proteins arose simply by blind luck or trial and error is an insult to a rational person. To think that even one pair of proteins, one to send and one to receive, arose separately by chance, by unguided and blind processes is a stretch; how much more the millions of proteins that are swarming through our bodies at any given time.
What does the ability to communicate imply? Simply put, intelligence. Life requires it, from the seemingly simplest prokaryote to the most complex eukaryote. Intelligence requires an outside cause, it is not inherent in carbon or nitrogen atoms. Life could not arise in a hundred billion years without communication, which is by necessity a requirement of any ordered and organized system, such as any cell. Without communication, there is no organization. Without communication, there is no ability to navigate an environment, no ability to find nutrition sources or protect from threats, no ability whatsoever to grow and divide, no adaptation, no interpretation of sensory input, no method to start any process that is required for life. Without communication, there can be no life. Or else, why are astronomers tuning the world’s largest telescopes skyward? To find signs of intelligent life. How exactly will they know they have found it? Communication, a signal of some kind. They would be beside themselves if such an event actually happened, yet they dismiss the ability of our own bodies to communicate in the fantastic ways described above, and would rather attribute it to chance or blind luck, rather than an intelligent Creator that has placed this longing and curiosity for the stars in us.