Galanin and galanin receptors in embryonic stem cells: accidental or essential?

Galanin is a peptide consisting of 29 (mouse) or 30 (human) amino acids that was recently identified in undifferentiated mouse embryonic stem (ES) cells through transcriptome analyses. Galanin is known to have important modulatory roles in neuronal cells, but it is currently unclear what biological role, if any, galanin has in stem cells. Here we show that galanin transcripts represent a distinguishing molecular feature of embryonic stem cell lines and that all three galanin receptors subtypes are expressed in mouse ES cells (Gal-R2>Gal-R3≫Gal-R1). Based on cell culture data, galanin in a dose-dependent manner appears to regulate growth characteristics of ES cells, at least partially, through interactions with leukemia inhibitory factor (LIF), a cytokine implicated in the self-renewal process of ES cells. The regulation of ES cell growth can therefore be added to the list of biological processes regulated by this peptide.