| First Author | Kim DY | Year | 2011 |
| Journal | J Biol Chem | Volume | 286 |
| Issue | 10 | Pages | 8106-16 |
| PubMed ID | 21190943 | Mgi Jnum | J:170564 |
| Mgi Id | MGI:4946878 | Doi | 10.1074/jbc.M110.134692 |
| Citation | Kim DY, et al. (2011) Reduced sodium channel Na(v)1.1 levels in BACE1-null mice. J Biol Chem 286(10):8106-16 |
| abstractText | The Alzheimer BACE1 enzyme cleaves numerous substrates, with largely unknown physiological consequences. We have previously identified the contribution of elevated BACE1 activity to voltage-gated sodium channel Na(v)1.1 density and neuronal function. Here, we analyzed physiological changes in sodium channel metabolism in BACE1-null mice. Mechanistically, we first confirmed that endogenous BACE1 requires its substrate, the beta-subunit Na(v)beta(2), to regulate levels of the pore-forming alpha-subunit Na(v)1.1 in cultured primary neurons. Next, we analyzed sodium channel alpha-subunit levels in brains of BACE1-null mice at 1 and 3 months of age. At both ages, we found that Na(v)1.1 protein levels were significantly decreased in BACE1-null versus wild-type mouse brains, remaining unchanged in BACE1-heterozygous mouse brains. Interestingly, levels of Na(v)1.2 and Na(v)1.6 alpha-subunits also decreased in 1-month-old BACE1-null mice. In the hippocampus of BACE1-null mice, we found a robust 57% decrease of Na(v)1.1 levels. Next, we performed surface biotinylation studies in acutely dissociated hippocampal slices from BACE1-null mice. Hippocampal surface Na(v)1.1 levels were significantly decreased, but Na(v)1.2 surface levels were increased in BACE1-null mice perhaps as a compensatory mechanism for reduced surface Na(v)1.1. We also found that Na(v)beta(2) processing and Na(v)1.1 mRNA levels were significantly decreased in brains of BACE1-null mice. This suggests a mechanism consistent with BACE1 activity regulating mRNA levels of the alpha-subunit Na(v)1.1 via cleavage of cell-surface Na(v)beta(2). Together, our data show that endogenous BACE1 activity regulates total and surface levels of voltage-gated sodium channels in mouse brains. Both decreased Na(v)1.1 and elevated surface Na(v)1.2 may result in a seizure phenotype. Our data caution that therapeutic BACE1 activity inhibition in Alzheimer disease patients may affect Na(v)1 metabolism and alter neuronal membrane excitability in Alzheimer disease patients. |
