Neuronal SLC39A8 deficiency impairs cerebellar development by altering manganese homeostasis
Eun-Kyung Choi, Luisa Aring, Yujie Peng, Adele B. Correia, Andrew P. Lieberman, Shigeki Iwase, Young Ah Seo
Eun-Kyung Choi, Luisa Aring, Yujie Peng, Adele B. Correia, Andrew P. Lieberman, Shigeki Iwase, Young Ah Seo
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Research Article Genetics Neuroscience

Neuronal SLC39A8 deficiency impairs cerebellar development by altering manganese homeostasis

Abstract

Solute carrier family 39, member 8 (SLC39A8), is a transmembrane transporter that mediates the cellular uptake of zinc, iron, and manganese (Mn). Human genetic studies document the involvement of SLC39A8 in Mn homeostasis, brain development, and function. However, the role and pathophysiological mechanisms of SLC39A8 in the central nervous system remain elusive. We generated Slc39a8 neuron-specific knockout (Slc39a8-NSKO) mice to study SLC39A8 function in neurons. The Slc39a8-NSKO mice displayed markedly decreased Mn levels in the whole brain and brain regions, especially the cerebellum. Radiotracer studies using 54Mn revealed that Slc39a8-NSKO mice had impaired brain uptake of Mn. Slc39a8-NSKO cerebellums exhibited morphological defects and abnormal dendritic arborization of Purkinje cells. Reduced neurogenesis and increased apoptotic cell death occurred in the cerebellar external granular layer of Slc39a8-NSKO mice. Brain Mn deficiency in Slc39a8-NSKO mice was associated with motor dysfunction. Unbiased RNA-Seq analysis revealed downregulation of key pathways relevant to neurodevelopment and synaptic plasticity, including cAMP signaling pathway genes. We further demonstrated that Slc39a8 was required for the optimal transcriptional response to the cAMP-mediated signaling pathway. In summary, our study highlighted the essential roles of SLC39A8 in brain Mn uptake and cerebellum development and functions.

Authors

Eun-Kyung Choi, Luisa Aring, Yujie Peng, Adele B. Correia, Andrew P. Lieberman, Shigeki Iwase, Young Ah Seo

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Figure 3

Morphological defects, reduced neurogenesis, and accelerated apoptosis in Slc39a8-NSKO cerebellum.

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Morphological defects, reduced neurogenesis, and accelerated apoptosis i...
(A) H&E-stained sagittal sections of paraffin-embedded mouse brains from 4-week-old control and Slc39a8-NSKO mice. Numerals indicate the lobules, and the fissures between lobules VI and VII of cerebellums are outlined with red lines and indicated by red arrows. Scale bars: 1,000 μm. Upper original magnification, 2×, and lower original magnification, 10×. (B) Immunohistochemical staining of cerebellar Purkinje cells (PCs) with anti-calbindin antibody. PC morphologies of control and Slc39a8-NSKO mice at P14. EGL, external granule cell layer; ML, molecular layer; PCL, Purkinje cell layer; IGL, internal granule cell layer. Scale bars: 25 μm. (C) Numbers of PCs at P14. (D) BrdU staining on the cerebellar sections at P14. Scale bars: 100 μm. (E) The number of BrdU+ cells per unit size of sagittal sections from the entire cerebellum was quantified. (F) TUNEL staining on the cerebellar sections at P14. Scale bars: 200 μm. Insets original magnification, 20×. (G) Quantification of the number of TUNEL-positive cells per field of cerebellar folia. At least 9 sections from 3 animals per genotype were quantified for all panels. Data are presented as individual values and represent the mean ± SEM. * P < 0.05, ** P < 0.01, and *** P < 0.001.