Problems in cell signalling can be bad news
When messages between cells are blocked or scrambled, there are usually harmful results. Autoimmune diseases, in which our own immune cells attack body tissues, are partly caused by errors in identifying cells. In multiple sclerosis, misdirected T cells remove the electrically insulating sheath around neurons; tumours begin when cells ignore signals telling them not to replicate or when they misread signals to keep dividing. Teratomas (tumours that can contain hair, teeth and bone) arise from germ cells (sperm and eggs) that are triggered to begin dividing inside the body.
Some diseases affect cell–cell signalling directly. In Alzheimer’s disease, toxic clumps of a protein called amyloid appear in the brain. They build up from fragments of a precursor protein present at synapses, which is abnormally processed.
Another example is diabetes. In type 1 diabetes, sugar metabolism gets out of control because the cells that make the hormone insulin die off. In the more common type 2 diabetes, there is insulin in the circulation, but the cells that normally respond to it do not respond to the signal.Lead image:
Dr David Furness/Wellcome Images CC BY NC