Overexpression of Na+/Mg2+ exchanger SLC41A1 attenuates pro-survival signaling

Abstract

The Na+/Mg2+ exchanger SLC41A1 (A1), a key component of intracellular Mg homeostasis (IMH), is the major cellular Mg2+ efflux system, and its overexpression decreases [Mg2+]intracellular. IMH plays an important role in the regulation of many cellular processes, including cellular signaling. However, whether the overexpression of A1 and the consequent drop of [Mg2+]i impact on intracellular signaling is unknown.To examine the latter, we utilized dynamic mass redistribution (DMR) assay, PathScan® RTK signaling antibody (PRSA) array, confirmatory Western blot (WB) analyses of phosphorylation of kinases selected by PRSA, and mag-fura 2-assisted fast filter spectrometry (FFS).We demonstrate here that the overexpression of A1 quantitatively and qualitatively changes the DMR signal evoked by the application of PAR-1-selective activating peptide and/or by changing [Mg2+]extracellular in HEK293 cells. PRSA profiling of the phosphorylation of important signaling nodes followed by confirmatory WB has revealed that, in HEK293 cells, A1 overexpression significantly attenuates the phosphorylation of Akt/PKB on Thr308 and/or Ser473 and of Erk1/2 on Thr202/Tyr204 in the presence of 0 or 1 mM (physiological) Mg2+ in the bath solution. The latter is also true for SH-SY5Y and HeLa cells. Overexpression of A1 in HEK293 cells significantly lowers [Mg2+]i in the presence of [Mg2+]e = 0 or 1 mM. This correlates with the observed attenuation of prosurvival Akt/PKB – Erk1/2 signaling in these cells.Thus, A1 expression status and [Mg2+]e (and consequently also [Mg2+]i) modulate the complex physiological fingerprint of the cell and influence the activity of kinases involved in anti-apoptotic and, hence, pro-survival events in cells.

Comprehensive analysis of PM20D1 QTL in Alzheimer’s disease

“…4c), but instead proved to be detrimental per se (Fig. 4d), which is reminiscent of a previous report in which SLC41A1 overexpression was shown to reduce cell survival in multiple cell lines [21]. Counterintuitively, the AD-risk haplotype [11] is associated with lower levels of SLC41A1 expression, together with PM20D1, which seems to indicate (See figure on previous page.)…”

“…On the contrary, both the overexpression and the depletion of SLC41A1 have been found to be detrimental. SLC41A1 overexpression reduced cell survival in multiple cell lines [21], while morpholino-mediated depletion induced severe developmental abnormalities in zebrafish [24], which suggests the need of well-controlled levels of SLC41A1. Interestingly, both PM20D1 and SLC41A1 are expressed by astrocytes [25] and might therefore be indirectly associated with increased levels of gliosis in AD [17,26].…”

Carbonate Apatite Nanoparticles-Facilitated Intracellular Delivery of siRNA(s) Targeting Calcium Ion Channels Efficiently Kills Breast Cancer Cells

“…TRPC6 was found to be overexpressed in mRNA and protein levels in breast carcinoma specimens in comparison to normal breast tissue, indicating its potential role in breast carcinogenesis [ 31 ], whereas TRPM7 regulates proliferation, migration, invasion, and metastasis of breast cancer cells depending on the stimulation of their ion channels and kinase domains [ 32 , 33 ] and TRPM8 is involved in the initiation and progression of tumors with its aberrant expression found in varieties of tumors including breast adenocarcinoma [ 34 ]. The Na + /Mg 2+ exchanger SLC41A1 (A1) is the major cellular Mg 2+ efflux system, which, when overexpressed, decreases intracellular Mg 2+ and influences the activity of kinases of anti-apoptotic and pro-survival pathways [ 35 ]. ORAI1 and ORAI3 are plasma membrane-embedded calcium channels having roles in cellular calcium homeostasis by allowing Ca 2+ to enter and refill the sarcoplasmic/endoplasmic reticulum Ca 2+ stores [ 36 ].…”

Magnesium, Oxidative Stress, Inflammation, and Cardiovascular Disease

“…Presented in Figure 1 are the effects of Mg deficiency on mitochondria. Intracellular Mg deficiency has been shown to disrupt mitochondrial function by altering coupled respiration [ 50 , 89 , 90 ], increasing mitochondrial ROS production [ 1 , 82 , 110 ], suppressing the antioxidant defense system (such as superoxide dismutase (SOD), catalase, glutathione, and Parkinsonism associated deglycase PARK7/DJ-1) [ 105 , 111 , 112 , 113 , 114 ], inducing mitochondrial Ca overload via the mitochondrial Ca uniporter [ 1 , 54 , 115 ], attenuating pro-survival signaling [ 116 , 117 , 118 ], and promoting opening of mitochondrial ATP-sensitive potassium (K) channel [ 119 ], inner membrane anion channel [ 120 ] and mitochondrial permeability transition pore (PTP) [ 121 ]. The effects result in depolarization of the mitochondrial membrane potential (ΔΨ m ) [ 54 ].…”