| First Author | Zhang J | Year | 2020 |
| Journal | Am J Physiol Cell Physiol | Volume | 319 |
| Issue | 6 | Pages | C1107-C1119 |
| PubMed ID | 32997514 | Mgi Jnum | J:302108 |
| Mgi Id | MGI:6501470 | Doi | 10.1152/ajpcell.00083.2020 |
| Citation | Zhang J, et al. (2020) Regulation of Na/K-ATPase expression by cholesterol: isoform specificity and the molecular mechanism. Am J Physiol Cell Physiol 319(6):C1107-C1119 |
| abstractText | We have reported that the reduction in plasma membrane cholesterol could decrease cellular Na/K-ATPase alpha1-expression through a Src-dependent pathway. However, it is unclear whether cholesterol could regulate other Na/K-ATPase alpha-isoforms and the molecular mechanisms of this regulation are not fully understood. Here we used cells expressing different Na/K-ATPase alpha isoforms and found that membrane cholesterol reduction by U18666A decreased expression of the alpha1-isoform but not the alpha2- or alpha3-isoform. Imaging analyses showed the cellular redistribution of alpha1 and alpha3 but not alpha2. Moreover, U18666A led to redistribution of alpha1 to late endosomes/lysosomes, while the proteasome inhibitor blocked alpha1-reduction by U18666A. These results suggest that the regulation of the Na/K-ATPase alpha-subunit by cholesterol is isoform specific and alpha1 is unique in this regulation through the endocytosis-proteasome pathway. Mechanistically, loss-of-Src binding mutation of A425P in alpha1 lost its capacity for regulation by cholesterol. Meanwhile, gain-of-Src binding mutations in alpha2 partially restored the regulation. Furthermore, through studies in caveolin-1 knockdown cells, as well as subcellular distribution studies in cell lines with different alpha-isoforms, we found that Na/K-ATPase, Src, and caveolin-1 worked together for the cholesterol regulation. Taken together, these new findings reveal that the putative Src-binding domain and the intact Na/K-ATPase/Src/caveolin-1 complex are indispensable for the isoform-specific regulation of Na/K-ATPase by cholesterol. |
