Abstract
Purpose:
To analyze transcriptomic alterations in mouse retina after long-term cigarette smoke exposure, which is a major modifiable risk factor for eye diseases such as age-related macular degeneration.
Methods:
25 C57BL/6 mice (10 weeks of age, male) were exposed to cigarette smoke for 4 hours a day and 5 days a week for 6 months. Another 25 mice were kept in a filtered air environment as controls. Total RNAs were extracted from tissues containing neuroretina-RPE. After ribosome RNA was depleted, sequencing libraries were constructed following the standard Illumina protocols and processed by Hiseq2500 sequencers. Differential gene expression was calculated by EdgeR, DESeq and BaySeq. The intersection of the 3 methods were taken and transformed into a list of the final differentially expressed features. Differentially expressed features were determined by cutoff adjusted P-values of 0.05 across all 3 methods. <br />
Results:
199 genes were differentially expressed by analysis of EdgeR, 23 genes by analysis of DEseq, and 39 genes by analysis of Bayseq respectively. However, only 11 genes including a few of non-coding transcripts were significantly and differentially expressed in the analyses of all three methods. Of the 11 genes, the most significant changes occurred in three histone genes, Hist1h2af, Hist1h4h and Hist2h2ac, which were increased 24.7 fold, 13.1 fold and 8.9 fold respectively.
Conclusions:
These results suggest that cigarette smoke exposure causes a dramatic increase in the expression of histones, which may result in disruptions in chromatin structures and cellular functions.