From Aging: Why do old flies die?
As we get older we become more likely to get sick and, eventually, die. Although the underlying pathologies and major causes of death in elderly humans have been well documented, much less is known about the events leading to age-related death in the fruit fly Drosophila melanogaster- one of the premier model systems in aging research. What is the underlying pathology that limits the lifespan of a fly? […]
In this work, we show that all individuals show an altered control of intestinal permeability a few days prior to death regardless of chronological age. Interestingly, these same individuals also showed a striking increase in the expression of inflammatory markers (antimicrobial peptides, AMPs) as well as systemic metabolic defects, including impaired insulin/insulin-like growth factor signaling (IIS). […]
As well as highlighting an important link between intestinal aging and organismal aging, this work may be telling us something about the very nature of the aging process itself. Our findings support a model where aging is composed of two consecutive phases, a first phase characterized by a growing likelihood of displaying intestinal barrier failure/inflammation/systemic metabolic dysfunction followed by a second phase leading to death.
Interestingly, it looks like impaired insulin signaling (insulin resistance), is important in the deaths of fruit flies as well as humans.