Study On The Age-related Changes In The Expression Of SIRT1and FoxO3a In Human Leukocyte

Background In the practice of forensic science, estimation of age is mainlybased on calculating osteal markers of bones and teeth with the model of forensicanthropology. This technology has been well developed with its acceptable error.However, the application of this method is confined in cases of missing bones andteeth. Researchers pay considerable attentions to the methods of age estimation basedon telomere shortening, mitochondrial DNA’s injury and DNA methylation. But forvarious reasons, these methods are difficult to be used in the practice of forensicscience. In recent years, with the development of geratology, there are growingevidences to prove that Sirtuin1(SIRT1) and Forkhead Box O3a (FoxO3a) playsignificant roles in cell senescence, which suggests that SIRT1and FoxO3aexpression may be associated with age. Therefore, by setting up a mathematicalmodel between the expression profile of SIRT1and FoxO3a and age, it has thepotential to be a new method to estimate age in the future.Objective To analyze the change trend of SIRT1and FoxO3a expression withage by detecting the mRNA expression levels of SIRT1and FoxO3a in different agesets, and lay the foundation to further establish the mathematical model between theabundance of their mRNA and age.Methods80peripheral blood samples of healthy individuals were collectedfrom Hubei Tongji Center for Medicolegal Expertise and divided into8groups:≤9years old,10to19years old,20to29years old,30to39years old,40to49years old,50to59years old,60to69years old and≥70years old groups, and10samples ineach group. After total RNA was extracted, the real-time polymerase chain reaction (RT-PCR) technique was used to quantitatively analyze mRNA expression of SIRT1and FOXO3a in human leukocyte. Data were analyzed by software SPSS.Results⑴There were no significant differences for the relative expressionlevel of mRNA of SIRT1among the younger than9years old,10to19years old,20to29years old,30to39years old,40to49years old and50to59years old groups (P＞0.05)while the relative expression level of mRNA of SIRT1in the60to69years old andover70years old groups were significantly higher than other groups (P＜0.01)，and thedifference between these two groups was also significant (P＜0.01). The expressionlevel of SIRT1mRNA in human leukocyte was positively correlated with age（r=0.708, P＜0.01），and the fitting curve was Y＝0.005X3－0.002X2－0.004(R2=0.884, P＜0.01）when the age group was used as independent variable and therelative expression level of SIRT1mRNA as variable；⑵There were no significantdifferences for the relative expression level of mRNA of FoxO3a between the youngerthan9years old and10to19years old groups, younger than9years old and20to29years old groups,10to19years old and20to29years old groups，20to29years oldand30to39years old groups，30to39years old and40to49years old groups (P＞0.05)while the differences between the other two groups were significant (P＜0.05). Theexpression level of FoxO3a mRNA in human leukocyte was positively correlated withage (r=0.841, P＜0.01), and the fitting curve was Y=0.001e0.418x(R2=0.935, P＜0.01)when the age group was used as independent variable and the relative expression levelof FoxO3a mRNA as variable.Conclusion⑴The expression level of the SIRT1mRNA in human leukocyteis very low when the age is less than60years old, but it increases significantly whenthe age is over60years old;⑵The expression level of FoxO3a mRNA in humanleukocyte increases with aging in healthy;⑶The FoxO3a mRNA in human leukocytecan be used as one of the indicators of the age estimation.