The ancient roots of calcium signalling evolutionary tree

Abstract

Molecular cascades of calcium homeostasis and signalling (Ca(2+) pumps, channels, cation exchangers, and Ca(2+)-binding proteins) emerged in prokaryotes and further developed at the unicellular stage of eukaryote evolution. With progressive evolution, mechanisms of signalling became diversified reflecting multiplication and specialisation of Ca(2+)-regulated cellular activities. Recent genomic analysis of organisms from different systematic positions, combined with proteomic and functional probing invigorated expansion in our understanding of the evolution of Ca(2+) signalling. Particularly impressive is the consistent role of Ca(2+)-ATPases/pumps, calmodulin and calcineurin from very early stages of eukaryotic evolution, although with interspecies differences. Deviations in Ca(2+) handling and signalling are observed between vertebrates and flowering plants as well as between protists at the basis of the two systematic categories, Unikonta (for example choanoflagellates) and Bikonta (for example ciliates). Only the B-subunit of calcineurin, for instance, is maintained to regulate highly diversified protein kinases for stress defence in flowering plants, whereas the complete dimeric protein, in vertebrates up to humans, regulates gene transcription, immune-defence and plasticity of the brain. Calmodulin is similarly maintained throughout evolution, but in plants a calmoldulin-like domain is integrated into protein kinase molecules. The eukaryotic cell has inherited and invented many mechanisms to exploit the advantages of signalling by Ca(2+), and there is considerable overall similarity in basic processes of Ca(2+) regulation and signalling during evolution, although some details may vary.

Astroglial calcium signalling in Alzheimer's disease

“…Calcium ions are the most ubiquitous and evolutionary ancient intracellular second messenger that controls various vital cellular functions and regulate physiological responses in virtually every living organism [36][37][38][39][40] [45][46][47]), transient receptor potential (TRP) channels [48,49] and sodium calcium exchanger (NCX), operating in the reverse mode [50]. The TRPC-containing channels [51] also contribute to the store-operated Ca 2+ entry initiated by the depletion of the ER store of releasable Ca 2+ [52,53].…”

Conflict and cooperation in eukaryogenesis: implications for the timing of endosymbiosis and the evolution of sex

“…Primitive calcium signalling employed to depolarize proto-mitochondrial membranes early in eukaryogenesis could be one such example. Indeed, multiple components of eukaryotic calcium signalling pathways derive from bacterial ancestors [28,29] including the recently identified homologue of the mitochondrial calcium uniporter in several bacterial species [30].…”

Calcium and ATP control multiple vital functions

“…As a result, the cytosol of the most primitive cellular ancestors contained exceedingly low levels of cytosolic free Ca 2þ . When the Ca 2þ concentration in the ocean started to increase (due to acidification and washout of Ca 2þ from the rocks) the development of a system controlling Ca 2þ movements across the cellular membrane became of vital importance, and provided evolutionary pressure for emergence of cellular Ca 2þ homeostatic and Ca 2þ -based signalling systems [1,2]. This rapid increase in the environmental [Ca 2þ ] instigated an explosive evolution of eukaryotes and then of multicellular life forms [3].…”