New method shows how light inhibits cell growth

Without light life cannot exist on our planet, since light energy can be converted into essential chemical energy in different organisms. But light can also cause cell damage and cell death. Therefore, organisms exposed to light have developed systems to protect themselves from its toxic effects.

“It is well known that photosynthetic organisms, such as plants, have different systems for limiting light absorption to keep the light from becoming too intense and thereby toxic. What we are interested in is understanding the mechanisms non-photosynthetic organisms use to protect themselves against visible light,” says Anders Blomberg, professor of functional genomics at the University of Gothenburg.

Visible light can also cause damage​

It is well known that ultraviolet light, which we cannot see (wavelengths less than 400 nanometres), causes serious damage to DNA. But it is unclear how and why visible light (wavelengths in the 400–700 nm spectrum) damages living organisms.

In a study published in BMC Biology the researchers show that a novel method can be used to determine in what way and why visible light inhibits cell growth.

“We used this method to understand how baker's yeast, a common model for human cells that is easy and problem-free to use in experiments, ethically speaking, protects itself from the toxic effects of light and what genes are necessary in this defence,” says Mikael Molin, associate professor at the Division of Systems and Synthetic Biology.

Earlier studies in Mikael Molin’s research group have identified a specific mechanism by which yeast cells register the levels of light, even though they, as many other cells and organisms, do not have conventional light receptors.

“Most humans, animals and plants adjust their activities depending on the daily shifts in light and darkness. Disturbances in circadian rhythms can increase the risks for both cancer and premature aging”, says Mikael Molin.

Fundamental defence mechanism discovered​

With the novel method the researchers found that a special signalling mechanism, called cAMP dependent protein kinase, is central for the ability of cells to sense and protect themselves from damage caused by visible light.

“Nearly all cell types, including most types of human cells, signal using this protein kinase, and this knowledge can thus help us understand how light affects many different life forms. This is an incredibly important insight,” says Jonas Warringer, researcher at the University of Gothenburg.

Read the study in BMC Biology: Protein kinase A controls yeast growth in visible light​