SLC41A1 is essential for magnesium homeostasis in vivo

Abstract

Solute carrier family 41 member A1 (SLC41A1) has been suggested to mediate magnesium (Mg 2+ ) transport by several in vitro studies. However, the physiological function of SLC41A1 remains to be elucidated. In this study, cellular Mg 2+ transport assays combined with zebrafish slc41a1 knockdown experiments were performed to disclose SLC41A1 function and its physiological relevance. The gene slc41a1 is ubiquitously expressed in zebrafish tissues and is regulated by water and dietary Mg 2+ availability. Knockdown of slc41a1 in zebrafish larvae grown in a Mg 2+ -free medium resulted in a unique phenotype characterized by a decrease in zebrafish Mg content. This decrease shows that SLC41A1 is required to maintain Mg 2+ balance and its dysfunction results in renal Mg 2+ wasting in zebrafish larvae. Importantly, the Mg content of the larvae is rescued when mouse SLC41A1 is expressed in slc41a1 -knockdown zebrafish. Conversely, expression of mammalian SLC41A1-p.Asp262Ala, harboring a mutation in the ion-conducting SLC41A1 pore, did not reverse the renal Mg 2+ wasting. 25 Mg 2+ transport assays in human embryonic kidney 293 (HEK293) cells overexpressing SLC41A1 demonstrated that SLC41A1 mediates cellular Mg 2+ extrusion independently of sodium (Na + ). In contrast, SLC41A1-p.Asp262Ala expressing HEK293 cells displayed similar Mg 2+ extrusion activities than control (mock) cells. In polarized Madin-Darby canine kidney cells, SLC41A1 localized to the basolateral cell membrane. Our results demonstrate that SLC41A1 facilitates renal Mg 2+ reabsorption in the zebrafish model. Furthermore, our data suggest that SLC41A1 mediates both Mg 2+ uptake and extrusion. Electronic supplementary material The online version of this article (10.1007/s00424-018-2234-9) contains supplementary material, which is available to authorized users.

Tubular flow activates magnesium transport in the distal convoluted tubule

“…TRPM7‐mediated Mg 2+ reabsorption is postulated to be regulated by the cyclin and CBS domain divalent metal cation transport mediator 2 (CNNM2) (13). Basolateral extrusion of Mg 2+ is mediated by the solute carrier family 41 member 1 (14). Transcellular Mg 2+ reabsorption in DCT is essential for the maintenance of Mg 2+ homeostasis because DCT is the last nephron segment regulating urinary Mg 2+ excretion and thus fine‐tuning urinary Mg 2+ excretion (15, 16).…”

“…TRPM7-mediated Mg 2+ reabsorption is postulated to be regulated by the cyclin and CBS domain divalent metal cation transport mediator 2 (CNNM2) (13). Basolateral extrusion of Mg 2+ is mediated by the solute carrier family 41 member 1 (14). Transcellular Mg 2+ reabsorption in DCT is essential for the maintenance of Mg 2+ homeostasis because DCT is the last nephron segment regulating urinary ABBREVIATIONS: 2-APB, 2-aminoethyl diphenyl borinate; CD, collecting duct; CNT, connecting tubule; CRISPR/Cas9, clustered regularly interspaced short palindromic repeat; DCT, distal convoluted tubule; FSS, fluid shear stress; PKD, polycystic kidney disease; PT, proximal tubule; qPCR, quantitative PCR; sgRNA, single guide RNA; TRPM, transient receptor potential cation channel subfamily melastatin; WT, wild type Mg 2+ excretion and thus fine-tuning urinary Mg 2+ excretion (15,16).…”

Rearing medium dictates variability across replicates in untreated and arsenic challenged zebrafish larvae

“…Another possibility is that embryo medium provides an essential component, such as Ca 2+ or Mg 2+ , which may provide an important supplement for hepatocellular function. Indeed, hypomagnesemia results in many disorders, including fatigue, seizures and muscle cramps [40]. Zebrafish primarily obtain their intake of magnesium from absorption through the water [40].…”

“…Indeed, hypomagnesemia results in many disorders, including fatigue, seizures and muscle cramps [40]. Zebrafish primarily obtain their intake of magnesium from absorption through the water [40]. Additionally, other studies have shown that zebrafish larvae body length are positively correlated with bioavailability of calcium and magnesium in the rearing medium [41].…”

“…Finally, it is possible that egg water could increase iAs susceptibility because of its debilitating effect on other organs. Studies have shown the importance of pathways involved in magnesium uptake in renal maintenance [40]. Another important mineral, calcium is required in bone formation, cardiac and kidney function [42].…”