oncogenesis

Evolutionary strategy is based upon finding an environmental niche and exploiting it. Evolution is based upon change and the natural adaptations to it. Today, we are going to explore how some environmental triggers might open a “biochemical trap door.” Why is circadian biology critical? For evolution to work, a cell first must adapt to its environment. So the first thing any living cell would see in an earth day is a period of day and night. It also has to find food to make energy (ATP). In addition, it has to control its own cellular division. The epic battle for the cell is the circadian cycle has to “yoke” the metabolic cycle to its growth cycle. Most people know that the suprachiasmatic nucleus (SCN), is the circadian pacemaker that monitors this dance between darkness and light and the seasonal cold and hot temperatures in our environment. Evolution apparently agreed with this assessment, because we now know it to be true. What most people do not know is how leptin plays a massive role in regulating it. Research has revealed that leptin can induce expression of a neuropeptide gene called vasoactive intestinal peptide (VIP) through the VIP cytokine response element. VIP actually is what sets the circadian pacemaker to light. Leptin yokes metabolism and sleep to the light and dark cycle. When temperature becomes the dominant environmental trigger and not light cycles, leptin induces endothelial nitric oxide synthetase (eNOS), that shuts down the photic effects of VIP on the SCN. This means that leptin forces the SCN not to be able to use light any longer to yoke circadian cycles! Once temperature begins to yoke the circadian rhythms, some very special things happen to our biochemistry that normally does not occur in other environments. These are ancient epigenetic programs that are hardwired into the DNA of every descendant of a eutherian mammal. We are descended from these animals.