What characteristics do cells exhibit when telomeres get shorter, just before cells reach senescence?
The expression of many cellular proteins changes. For example, in fibroblasts there are increases in the synthesis of proteases such as procollagenase, plasminogen activator, and stromelysin, while there are decreases in the synthesis of procollagen and tissue inhibitors of metalloproteases. It is thought that these changes may contribute to some of the age-related changes that occur for example in skin. It might take only 1- 5% of the fibroblasts in the dermis (which underlies the epidermis) to change protein expression to change the whole structure of skin. All of your cells do NOT have to get old in order to get wrinkled skin or for injuries not to heal as quickly. Sun protected epidermal keratinocytes of the skin is actually younger than sun damaged skin. In many instances sun damaged skin cells not only accumulate mutations but also have fewer proliferations left than the sun protected skin cells. The more sun damage to the skin, the more cell turn-over, and the more rapidly the t
