A group led by Assistant Professor Ryota Nakazato and Professor Koji Ikegami at Hiroshima University discovered that the length of the "primary cilia" growing on cells expands and contracts on a 24-hour cycle.
Each cell has a single "hair" several microns long called a "primary cilia," which plays a role in maintaining normal cell function while changing its shape depending on the state of the cell and the external environment. ing.
In this study, we discovered through culture experiments with mouse fibroblasts that the length of primary cilia expands and contracts with an approximately 24-hour cycle.In fibroblasts, the synthesis and decomposition of proteins called ``clock genes,'' which generate the body's internal clock, occur on a roughly 24-hour cycle, forming a circadian rhythm.They discovered that the length of primary cilia is also controlled by clock genes, forming a circadian rhythm in which they lengthen and contract in about 24 hours.
When fibroblasts are injured on the skin, they migrate to the wound site and work to heal the wound by releasing collagen and other substances, but fibroblasts have long primary cilia, while fibroblasts have short primary cilia. It was also revealed that the migration speed to the wound site was slower than that of fibroblasts during this period.For example, it has been reported that burns sustained at night take longer to heal than those sustained during the day; the time of day the injury occurs affects how quickly the wound heals. Although a different phenomenon is known, the length of the primary cilia of fibroblasts, which differ between day and night, may be one of the causes of this phenomenon.
It has been found through mouse experiments that the length of primary cilia in neurons and glial cells that make up the brain is longer at night than during the day.This discovery has revealed a new relationship between primary cilia and the body's internal clock, suggesting that primary cilia play a role not only in wound healing, but also in various biological mechanisms with circadian rhythms, such as sleep, wakefulness, hormone secretion, and body temperature changes. It is possible that it is also involved.The results of this research are expected to lead to a new understanding of the body clock and the development of ``chronotherapy,'' which incorporates knowledge about the body clock into medical care.
Paper information:[EMBO Reports] Circadian oscillation in primary cilium length by clock genes regulate fibroblast cell migration
