TGF‐β Signaling Regulates SLC8A3 Expression and Oxidative Stress in Mouse Developing Dopaminergic Neurons

Abstract

Calcium homeostasis is a cellular process required for proper cell function and survival, and maintained by the coordinated action of several transporters, among them members of the NCX family, such as SLC8A3, the isoform 3 of the Na+/Ca2+ exchanger (NCX3). Transforming growth factor beta (TGF‐β) signaling belongs to signaling cascades defining development and survival of several neuronal groups and known to regulate several channels and transporters. We have generated a conditional knockout mouse with cell‐type specific deletion of TGF‐β signalling from Engrailed 1 (En1) expressing cells, i.e. in cells derived from rhombomere r1. Subsequently, we have investigated regulation of SLC8A3, and elucidated the underlying molecular mechanisms. The results show that SLC8A3 expression is significantly downregulated in developing dopaminergic and serotonergic neurons from mutant mice and that low SLC8A3 abundance prevents the expression of the anti‐apoptotic Bcl‐xL. We also show that TGF‐β signaling regulates SLC8A3 expression via the canonical (Smad‐dependent) and MAPK signaling pathways and chromatin immunoprecipitation has revealed that TGF‐β signaling directly regulates transcription of Slc8a3 through binding of Smad4 to the Slc8a3 promoter. Moreover, expression of the lipid peroxidation markers malondialdehyde (MDA) and 4‐hydroxynonenal (4HNE) was upregulated in dopaminergic neurons lacking TGF‐β signaling. These results suggest that TGF‐β signaling regulates SLC8A3 expression in developing dopaminergic and serotonergic neurons thereby preventing oxidative stress.Support or Funding InformationDeutsche Forschungsgemeinschaft (DFG) [Kr1477/10‐3]