Science CommuniCa 2+ tion Developing Scientific Literacy on Calcium: The Involvement of CRAC Currents in Human Health and Disease.

All human life starts with a calcium (Ca 2+ ) wave. This ion regulates a plethora of cellular functions ranging from fertilisation and birth to development and cell death. A sophisticated system is responsible for maintaining the essential, tight concentration of calcium within cells. Intricate components of this Ca 2+ network are store-operated calcium channels in the cells' membrane. The best-characterised store-operated channel is the Ca 2+ release-activated Ca 2+ (CRAC) channel. Currents through CRAC channels are critically dependent on the correct function of two proteins: STIM1 and Orai1. A disruption of the precise mechanism of Ca 2+ entry through CRAC channels can lead to defects and in turn to severe impacts on our health. Mutations in either STIM1 or Orai1 proteins can have consequences on our immune cells, the cardiac and nervous system, the hormonal balance, muscle function, and many more. There is solid evidence that altered Ca 2+ signalling through CRAC channels is involved in the hallmarks of cancer development: uncontrolled cell growth, resistance to cell death, migration, invasion, and metastasis. In this work we highlight the importance of Ca 2+ and its role in human health and disease with focus on CRAC channels.