Discussion On The Substance Essence Of Traditional Chinese Medicine From The Change Of Circadian Rhythm Of Cell Function

AimFive internal organs (five zang), is one of the central features of traditional Chinese Medicine, correspond to the five major organ systems in our bodies, including liver (gan), heart (xin), spleen (pi), lung(fei) and kidney (shen). In classical Chinese medicine, the system was not based on the physical objects of the "organs", but developed by considering person as a whole and described in details about the interrelationship between humans and the environment. In this study, we hypothesized that "five organ theory" may involved both organelle function and circadian function in each particular cell. To find out whether the hypothesis is reasonable, we analyzed the changes of oscillation genes’ expression in different organs over time and looked deeply to the common functions involved by these circadian genes in different tissues. Our main goal is to understand and depict "zang" with modern biological terms.MethodsRaw gene expression data was obtained from GEO database (GEO Accession GSE54652). Data was pre-process using biocLite package from R. Two analysis have been done to find out the relationship between functional change of oscillation genes across time and the description of "zang" in Chinese medicine. Firstly, we analyze the distribution of oscillating genes across 24 hours in different organ, and identified the transcriptional "rush hours" for each organ. Secondly, CT8, CT12, CT19 and CT22 are chosen as the time of observation (CT8, CT12,,CT19 and CT22 represent the functional peak of heart, lung, kidney and liver respectively in Chinese Medicine). Gene list from organs with more than 100 circadian genes transcriptional peaked at each selected time point are used for further analysis. Gene Ontology enrichment analysis is run using ClueGOv2.1.5 to find out functional overlap between different organs at each time pointResultsWe found that the transcriptional of oscillation genes in liver peaked at dawn, transcriptional of oscillation genes in lung peaked at dusk, whilst transcriptional of oscillation genes in kidney peaked at midnight. These organ-based circadian rhythm is in agreement with the understanding of Chinese Medicine. Furthermore, GO enrichment results showed that oscillation genes in different organ commonly involved post-translational modification at CT8; involved cells transportation at CT12; involved negative regulation of biosynthetic process and response to oxidative stress at CT19, involved regulation of cell cycle and peptidase activity at CT22.ConclusionCurrent results give us a clue that Five internal organs (Five Zang) in Chinese Medicine may comprise both physical organ itself and circadian rhythm of the body. Integrating systemic level-analysis of circadian rhythm to Chinese medicine research is feasible and may expand our perception on how our bodies work, from the view of macroscopic to microscopic.