Teneurin C-Terminal Associated Peptides (TCAPs): Evolutionary Origins and the Role of TCAP-1 on Calcium Flux in Astrocyte Monocultures and in Astrocytes Co-Cultured with Neuron

Teneurin C-terminal associated peptides (TCAPs) are a family of 40--41 amino acid peptides located at the C-terminus of each of the four teneurin type II transmembrane proteins. The teneurin-TCAP system is ancient and likely arose as a result of a horizontal gene transfer event. TCAPs share sequence similarity to the Secretin superfamily, a less evolutionarily ancient family that includes corticotropin-releasing factor (CRF). The phylogenetic position of TCAP places it as a putative ancestor of the Secretin superfamily. Calcium ion signaling is integral to all living organisms and astrocytes are integral to the development of the central nervous system in chordates. It is likely that TCAP played a role in these mechanisms. TCAP-1 stimulated calcium signaling in astrocyte monocultures but not in astrocytes co-cultured with neurons. This effect is mediated, in part, by the glutamatergic system. Therefore, the ancient peptide TCAP-1 plays a role in regulating calcium flux in astrocytes.