Loss of SLC30A10 manganese transporter alters expression of neurotransmission genes and activates hypoxia-inducible factor signaling in mice
The essential metal manganese (Mn) induces neuromotor disease at elevated levels. The manganese efflux transporter SLC30A10 regulates brain Mn levels. Homozygous loss-of-function mutations in SLC30A10 induce hereditary Mn neurotoxicity in humans. Our prior characterization of Slc30a10 knockout mice recapitulated the high brain Mn levels and neuromotor deficits reported in humans. But, mechanisms of Mn-induced motor deficits due to SLC30A10 mutations or elevated Mn exposure are unclear. To gain insights into this issue, we characterized changes in gene expression in the basal ganglia, the main brain region targeted by Mn, of Slc30a10 knockout mice using unbiased transcriptomics. Compared with littermates, >1,000 genes were upregulated or downregulated in the basal ganglia sub-regions (i.e., caudate putamen, globus pallidus, and substantia nigra) of the knockouts. Pathway analyses revealed notable changes in genes regulating synaptic transmission and neurotransmitter function in the knockouts that may contribute to the motor phenotype. Expression changes in the knockouts were essentially normalized by a reduced Mn chow, establishing that changes were Mn-dependent. Upstream regulator analyses identified hypoxia-inducible factor (HIF) signaling, which we recently characterized to be a primary cellular response to elevated Mn, as a critical mediator of the transcriptomic changes in the basal ganglia of the knockout mice. HIF activation was also evident in the liver of the knockout mice. These results: (1) enhance understanding of the pathobiology of Mn-induced motor disease; (2) identify specific target genes/pathways for future mechanistic analyses; and (3) independently corroborate the importance of the HIF pathway in Mn homeostasis and toxicity. Overall design: To analyze Mn-induced gene expression changes that may influence motor function in an unbiased manner, we performed Tag-seq analyses in basal ganglia (Caudate Putament, Substantia Nigra, Globus Pallidus) and Liver tissue collected from ~1-month old littermate control or full-body Slc30a10 knockout mice fed regular rodent chow (~84 µg Mn/g chow)