Magt1, or magnesium transporter 1, is a subunit of the oligosaccharide protein complex with thiol-disulfide oxidoreductase activity, playing a crucial role in the process of N-glycosylation [1,2,3,5,6]. It is also involved in maintaining magnesium homeostasis, which is essential for over 600 enzymatic reactions in the human body, including energy metabolism and protein synthesis [4]. Additionally, magnesium and Magt1 are key molecular players for T cell-mediated immune responses [2].

In Magt1-deficient mice (Magt1 -/y), accelerated occlusive arterial thrombus formation, shortened bleeding time, and profound brain damage upon focal cerebral ischemia were observed. These defects were due to increased calcium influx and enhanced second-wave mediator release, reinforcing platelet reactivity and aggregation responses. Supplementation of MgCl2 or pharmacological blockade of TRPC6 channel normalized the aggregation responses of Magt1 -/y platelets. GPVI activation of Magt1 -/y platelets led to hyperphosphorylation of Syk, LAT, and PLCγ2, while the PKC-regulated inhibitory loop was impaired. Haploinsufficiency of TRPC6 in Magt1 -/y mice could normalize GPVI signaling, platelet aggregation, and thrombus formation in vivo, suggesting a functional link between Magt1 and TRPC6. Thus, Magt1 deficiency could be a potential risk factor for arterial thrombosis and stroke [1]. In XMEN disease patients with Magt1 deficiency, severe platelet dysfunction and impaired platelet glycoprotein N-glycosylation were found, with abnormal platelet morphology, impaired platelet aggregation, integrin activation, calcium mobilization, and protein kinase C activity. These defects were corrected after hematopoietic stem cell transplantation [3].

In conclusion, Magt1 is essential for N-glycosylation, magnesium homeostasis, and T cell-mediated immune responses. Research using Magt1-deficient mouse models has revealed its role in platelet function, arterial thrombosis, and stroke, as well as in XMEN-associated platelet dysfunction. Understanding Magt1's functions provides insights into the mechanisms of these disease conditions, potentially guiding future therapeutic strategies.

References:

1. Gotru, Sanjeev Kiran, Mammadova-Bach, Elmina, Sogkas, Georgios, Gudermann, Thomas, Braun, Attila. 2023. MAGT1 Deficiency Dysregulates Platelet Cation Homeostasis and Accelerates Arterial Thrombosis and Ischemic Stroke in Mice. In Arteriosclerosis, thrombosis, and vascular biology, 43, 1494-1509. doi:10.1161/ATVBAHA.122.318115. https://pubmed.ncbi.nlm.nih.gov/37381987/

2. Trapani, Valentina, Shomer, Naomi, Rajcan-Separovic, Evica. . The role of MAGT1 in genetic syndromes. In Magnesium research, 28, 46-55. doi:. https://pubmed.ncbi.nlm.nih.gov/26422833/

3. Kauskot, Alexandre, Mallebranche, Coralie, Bruneel, Arnaud, Miot, Charline, Adam, Frédéric. 2023. MAGT1 deficiency in XMEN disease is associated with severe platelet dysfunction and impaired platelet glycoprotein N-glycosylation. In Journal of thrombosis and haemostasis : JTH, 21, 3268-3278. doi:10.1016/j.jtha.2023.05.007. https://pubmed.ncbi.nlm.nih.gov/37207862/

4. de Baaij, Jeroen H F, Hoenderop, Joost G J, Bindels, René J M. . Magnesium in man: implications for health and disease. In Physiological reviews, 95, 1-46. doi:10.1152/physrev.00012.2014. https://pubmed.ncbi.nlm.nih.gov/25540137/

5. Golloshi, Klevi, Mitchell, William, Kumar, Deepak, Castellino, Sharon M, Chandrakasan, Shanmuganathan. 2024. HLH and Recurrent EBV Lymphoma as the presenting manifestation of MAGT1 Deficiency: A Systematic Review of the Expanding Disease Spectrum. In Journal of clinical immunology, 44, 153. doi:10.1007/s10875-024-01749-y. https://pubmed.ncbi.nlm.nih.gov/38896122/

6. Blommaert, Eline, Cherepanova, Natalia A, Staels, Frederik, Foulquier, François, Matthijs, Gert. 2022. Lack of NKG2D in MAGT1-deficient patients is caused by hypoglycosylation. In Human genetics, 141, 1279-1286. doi:10.1007/s00439-021-02400-1. https://pubmed.ncbi.nlm.nih.gov/35182234/