| Objective: The aim of this study was to detect the m RNA and protein expression levels of ERCC1, XPF and XPG among different age groups in healthy ethnic Han Chinese individuals, and to analyze the correlation of the m RNA and protein expression levels with age, in order to find new molecular markers for forensic age estimation by establishing the mathematical model between the m RNA and protien expression levels and age.Methods: Peripheral blood samples were obtained from 150 unrelated healthy ethnic Han Chinese individuals, and were divided into 3 groups by their ages: group younger than 18 years old(50 cases),19 to 45 years old group(70 cases) and group over 46 years old(30 cases). Total RNA were extracted by Trizol, the plasma were centrifuged from the whole blood. Real-time quantitative reverse transcription polymerase chain reaction(RT-q PCR) was used to quantitatively analyze the m RNA relative expression levels of ERCC1, XPF and XPG in peripheral blood mononuclear cells(PBMCs). Enzyme linked immunosorbent assay(ELISA) was used to quantitatively analyze the protein expression levels of ERCC1,XPF and XPG in plasma. All statistical tests were analyzed by Spss13.0.Results:(1) The expression levels of ERCC1 and XPF in different age groups :There were no significant differences for the m RNA relative expression levels of ERCC1 and XPF in PBMCs between males and females(P>0.05). The m RNA relative expression levels of ERCC1 and XPF in PBMCs were respectively 1.6346±0.13681 and 1.7866±0.14652 in group younger than 18 between group younger than 18 years old and 19 to 45 years old or group over 46 years old(P<0.05), while no significant difference between 19 to 45 years old group and group over 46 years old(P>0.05). The XPG m RNA relative expression level in the group younger than 45 years old was negatively correlated with age(r=-0.811, P<0.01), but positive correlation was found between the XPG protein expression level and the age less than 45 years old(r=0.662,P<0.01). The fitting curve of the XPG m RNA relative expression level with age was Y=0.001x2- 0.1162 x + 3.4399(R2=0.7604,P<0.01), and the fitting curve of the XPG protein expression level with age was Y=7.5E-5x2 + 0.0005 x + 0.2017(R2=0.3364,P<0.01), when the age was used as independent variable and the m RNA or protein expression levels as variable. There were no significant differences for the XPG m RNA and protein expression levels between males and females(P>0.05).Conclusions:(1) The ERCC1, XPF and XPG m RNA relative expression in PBMCs and the protein expression in plasma were unrelated to gender.(2) The ERCC1 and XPF m RNA relative expression levels declined with the increase of age in PBMCs, however, the protein expression levels in plasma were unrelated to age.(3) The XPG m RNA relative expression level in PBMCs declined with the increase of age when less than 45 years old, while the protein expression level in plasma increased with age.(4) ERCC1,XPF and XPG genes can be used as new molecular markers for forensic age estimation. years old, 1.1104±0.09773 and 1.1058±0.11046 in 19 to 45 years old group,0.5073±0.07116 and 0.6694±0.0539 in group over 46 years old. Significant differences were found in the m RNA relative expression levels of ERCC1 and XPF between different age groups(group younger than 18 years old vs 19 to 45 years old group, 19 to 45 years old group vs group over 46 years old,group younger than 18 years old vs group over 46 years old)(P<0.05). The m RNA relative expression levels of ERCC1 and XPF were both negatively correlated with age. The correlation coefficient were-0.578 and-0.844, respectively. When the age was used as independent variable and the m RNA expression relative level as variable, the fitting curve of the ERCC1 m RNA relative expression level with age was Y=3.3E-5x2-0.0261 x +1.9175(R2=0.3244, P<0.01), and the fitting curve of the XPF m RNA relative expression level with age was Y=0.0003x2-0.0459x+ 2.0439(R2=0.729, P<0.01). There were no significant differences for the protein expression level of ERCC1 and XPF in plasma between different age groups or genders(P>0.05).(2) The XPG expression level in different age groups :The XPG m RNA relative expression levels in PBMCs were 2.3772±0.23548 in group younger than 18 years old, 1.1605±0.1355 in 19 to 45 years old group and 1.257±0.23284 in group over 46 years old,respectively. The XPG protein expression levels in plasma were 0.282±0.01213 in group younger than 18 years old, 0.4162±0.03275 in 19 to 45 years old group and 0.4646±0.06301 in group over 46 years old, respectively. There were significant differences for the m RNA and protein expression levels of XPG among different age groups, and significant differences were found in the m RNA and protein expression levels of XPG... |
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