Human adenovirus infection induces the overexpression of CLOCK protein in human lymphoblast cells

Circadian rhythms are biological processes that regulate metabolism, the immune system, hormones, behaviors, and other various biological processes in organisms. The molecular underpinning of circadian rhythms is a group of genes which regulate each other in transcription-translation feedback loops as an internal molecular clock in cells. Many factors can affect the circadian clock. Viruses, such as hepatitis virus, influenza virus, human immunodeficiency virus were reported to interplay with circadian rhythms in the host or cell level. Up to date, the relationship between viruses and circadian rhythms and its significance in biology, pharmacology and clinic are not entirely understood. We here report that human adenovirus infection could regulate circadian rhythms in cells. We found that human adenovirus infection induced protein overexpression of a core circadian gene CLOCK in human lymphoblast cells. The conditioned medium collected from the infected lymphoblast cell culture was able to infect other lymphoblast cell lines and induced CLOCK overexpression in them. In contrast to the previous studies that showed viral infections dampened the circadian oscillation, we found that the human adenovirus infection increased the amplitude of the circadian oscillation in U2OS cells. To our knowledge, this is the first time that adenovirus infection was found to regulate circadian rhythms in cells.