Research On The Relationship Between Senescence And Expression Of RecQ Family DNA Helicase In Importent Organs Of Mice

Objective:To investigate the expression of RecQ family DNA helicase(RecQ1,BLM,WRN,RecQ4)in importent organs of neonatal mice,growing mice,mature stage mice and aging mice and the correlation between the expression of RecQ family DNA helicase and senescence.Methods:The aging mouse model was established by injecting D-gal for 49 consecutive days,the mouse's survival status was observed and the weighs were recorded once every 7 days,and after the time of modeling,the organ index of liver and spleen of mice was calculated,and the histological changes of thymus and spleen of mice were observed by H-E staining.The expression of senescence-related protein P16 in mice liver was detected by Western Blot method,and the SOD activity and MDA content in serum of mice were detected by xanthine oxidase method and TBA method respectively.Biological identification of aging mouse model was performed.The expression levels of RecQ family helicase(RecQ1,BLM,WRN,RecQ4)in the liver,spleen and bone marrow of the mice at four stages(neonatal,growth,maturation and aging)were detected by Western Blot and IHC-P(no bone marrow was detected in neonatal mice).Results:1.The survival status of mice in D-gal aging model group was poor,the increased body weight of the mice in aging model group was lower than that in control group,the organ index of liver and spleen and the activity of SOD in serum was decreased from(180.7 ± 2.93)U/ml to(105.3 ± 4.8)U/ml(P<0.01)and MDA content rose from(4.03 ± 0.74)nmol/ml to(13.3 ±0.31)nmol/ml(P<0.01)and liver P16 protein expression of the mice increased in the aging model group.The above data of the aging model group were statistically significant compared with those in the control group(P<0.05).The spleen H-E staining slice showed that the blurring,white pith and red pith boundary blurred in the spleen marginal region of the aging model group,and the thymus H-E staining showed that the thymus cortex and medullary boundary were blurred and the distribution of the glandular cells was sparse.The results indicated that aging mice model was successfully constructed.2.The RecQ 1 immunohistochemical staining sections of liver of mice in neonatal stage,growth stage,maturity stage,and aging stage was observed,obtaining the mean optical density value of(0.148±0.036),(0.105±0.004)(P<0.05 compared with neonatal mice),(0.094±0.004)(P<0.01 compared with neonatal mice),and(0.073±0.008)(P<0.01 compared with neonatal mice)respectively.The expression level of RecQ1 protein in the liver of mice in neonatal stage,growth stage,maturity stage,and aging stage displayed a tendency of gradual decrease.RecQ1 protein was positive and similar in the spleen of the four developmental stages.The mean optical density value of immunohistochemicalstaining sections was respectively(0.130 ? 0.004),(0.109±0.017)(P<0.05 compared with neonatal mice),(0.112±0.001)(P<0.05 compared with neonatal mice),and(0.102±0.021)(P<0.05 compared with neonatal mice).RecQ1 protein demonstrated a higher expression level in the bone marrow of the mice of growth stage and maturity stage,while the expression level was decreased slightly in the bone marrow of the aging mice.The mean optical density value of immunohistochemical staining sections was(0.127 ± 0.027),(0.130 ± 0.012)and(0.122±0.001)respectively.3.The mean optical density of the liver BLM immunohistochemical staining sections in mice of neonatal stage,growth stage,maturity stage and aging stage was(0.142 ± 0.020),(0.106 ± 0.011)(P<0.05 compared with neonatal mice),(0.073 ± 0.005)(P<0.01 compared with neonatal mice),and(0.019 ± 0.0001)(P<0.01 compared with neonatal mice)respectively.The mean optical density of the spleen BLM immunohistochemical staining sections in mice of the four developmental stages was(0.123 ± 0.015),(0.087 ± 0.008)(P<0.01 compared with neonatal mice),(0.028 ± 0.001)(P<0.01 compared with neonatal mice),and(0.016 ± 0.001)(P<0.01 compared with neonatal mice)respectively.The mean optical density of the bone marrow BLM immunohistochemical staining sections in mice of growth stage,maturity stage and aging stage was(0.117 ± 0.003),(0.059 ± 0.001)(P<0.01 compared with growth stagel mice),and(0.014 ± 0.001)(P<0.01 compared with growth stage mice)respectively.The expression level of BLM protein in mice liver,spleen and bone marrow was negatively correlated with the aging of mice.4.The expression level of WRN protein in liver and spleen of mice in the four developmental stages was as follows.The expression level of neonatal mice was similar to that of the growing mice,while that of the mice in the mature stage were slightly lower(P<0.05 compared with neonatal mice).The expression level of WRN protein in aging mice decreased sharply(P<0.01 compared with neonatal mice).The expression level of WRN protein in the bone marrow of the growing mice was higher,followed by the mice of maturity stage,and that of the aging mice significantly decreased.(P<0.01 compared with growing mice)5.The expression level of RecQ4 protein in the liver of mice in four developmental stages showed a gradual decline.In the spleen,the expression level of RecQ4 protein decreased dramatically in the aging mice(P<0.01 compared with neonatal mice).In terms of the Bone marrow,the RecQ4 protein expression was the highest in the growth-stage mice,and that of the aging mice were significantly reduced(P<0.01 compared with growing mice).Conclusion:The expression of RecQ family DNA helicase in importent organs of mice are declined along with the growth of mice.The expression level of RecQ helicase family may be associated with the progress of aging,RecQ helicase is expected to become a new therapeutic target for the study of aging-related diseases.