The role of insulin-like growth factor in longevity.
Insulin-like growth factor and growth hormone (a regulator of circulating insulin-like growth factor) control growth and differentiation. Researchers from New York have identified gene variants responsible for longevity and suggest that lifespan can be modulated by components of insulin-like growth factor. Previous human studies reported on the role of insulin-like growth factor, however due to poor controls the results were difficult to interpret. To overcome this problem, researchers identified a unique cohort of individuals and their offspring who demonstrated exceptional longevity. All subjects were of Ashkenazi Jewish decent.
Researchers compared the levels of insulin-like growth factor in the offspring of centarians as plasma levels of the growth factor in centarians do not reflect their levels at a younger age. These levels were compared to a control group with no history of longevity so that alterations in the insulin-like growth factor signal pathway could be identified and considered for its role in exceptional longevity.
Female offspring showed 35% higher serum insulin-like growth factor levels compared with female controls, thus suggesting a gender specific alteration in the growth hormone/insulin-like growth hormone pathway. Researchers also established that higher insulin-like growth factor levels represent a compensatory response to reduce signalling and that this was linked to decreased height.
DNA from female centarians with heights below the mean for that population was then screened for any possible genetic variations in the IGF1 and IGFIR genes. There were no variations in the IGF1 gene. However the IGFIR gene demonstrated 20 sequence variations which were also previously unreported in the literature. Two non synonymous mutations and two synonymous mutations were reported as statistically significant. These mutations render the gene receptor slightly faulty so that insulin-like growth factor is faulty and the process of growth, development, maturation and ageing is slowed.
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|Publication:||Australian Journal of Medical Herbalism|
|Date:||Mar 22, 2008|
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