A caveolin binding motif in Na/K-ATPase is required for stem cell differentiation and organogenesis in mammals and C. elegans

Abstract

Several signaling events have been recognized as essential for regulating cell lineage specification and organogenesis in animals. We find that the gain of an amino-terminal caveolin binding motif (CBM) in the α subunit of the Na/K–adenosine triphosphatase (ATPase) (NKA) is required for the early stages of organogenesis in both mice and Caenorhabditis elegans. The evolutionary gain of the CBM occurred at the same time as the acquisition of the binding sites for Na+/K+. Loss of this CBM does not affect cell lineage specification or the initiation of organogenesis, but arrests further organ development. Mechanistically, this CBM is essential for the dynamic operation of Wnt and the timely up-regulation of transcriptional factors during organogenesis. These results indicate that the NKA was evolved as a dual functional protein that works in concert with Wnt as a hitherto unrecognized common mechanism to enable stem cell differentiation and organogenesis in multicellular organisms within the animal kingdom.

Stress Signal Regulation by Na/K-ATPase As a New Approach to Promote Physiological Revascularization in a Mouse Model of Ischemic Retinopathy

“…A more recently appreciated function of α1 NKA is its enzymatic-independent receptor function through its interaction with membrane and cytosolic proteins such as Src, caveolin-1, PI3K, and EGFR. 24 , 38 , 59 – 62 Highly relevant in the context of the present study, the α1 NKA/Src receptor complex forms a ROS amplification loop (Na/K-ATPase oxidant loop, NKAL 63 ), perpetuated at least in part through H 2 O 2 -induced carbonylation of Pro222 and Thr224 on α1 NKA and subsequent activation of Src. 30 , 64 The central role of this ROS amplification mechanism in OIR was experimentally revealed by a significant reduction of retinal ROS stress when NKAL was blocked by pNaKtide (carbonyls content) ( Fig.…”

“…The total number of cells was assessed using 4′,6-diamidino-2-phenylindole (DAPI) counterstaining as we have previously described. 38 Of note, the BrdU kit is based on an immunohistochemical reaction that involves denaturation of DNA with nucleases to increase the sensitivity of BrdU immunological detection. As a result, DAPI counterstaining is generally weaker in BrdU-positive cells, as shown in Figure 1 .…”

“…Specifically, protein carbonylation was measured by ELISA (BioCell Protein Carbonyl Assay Kit; BioCell Corp., Auckland, New Zealand) according to the manufacturer's protocol. Determination of α1 NKA, HIF-1α, and VEGF by western blot was done following sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) and transfer onto nitrocellulose using 40 µg of retinal lysate, as modified from our previously reported protocol, 38 and the following antibodies: anti-NASE (Texas Tech University, Lubbock, TX, USA), anti-HIF-1α (sc-13515; Santa Cruz Biotechnology, Dallas, TX, USA), and anti-VEGFA antibody (ab46154, Abcam, Cambridge, UK). Alpha-tubulin was used to ensure uniform sample loading in all western blots.…”

Non-Alcoholic Fatty Liver Disease Progression to Non-Alcoholic Steatohepatitis-Related Primary Liver Cancer

“…The importance of this signaling mechanism has been demonstrated in the pathogenesis of the metabolic syndrome, as well as in aging and embryonic development (46,47). For instance, genetic deletion of a caveolin binding motif (CBM) at the α1-NKA resulted in a lethal embryonic phenotype in homozygous mice, despite normal NKA protein expression and ion pumping function (47). This observation indicates that α1-NKA-CAV-1 interaction is necessary for the proper execution of developmental signaling pathways.…”

Inverse agonism at the Na/K‐ATPase receptor reverses EMT in prostate cancer cells

“…Na/K-ATPase α1 (NKA), a transmembrane ion pump 5 and a fundamental signaling mechanism in cell proliferation and differentiation, [6][7][8][9] may be one such target. Indeed, NKA expression at the plasma membrane is an important determinant of epithelial apical-basal polarity and maintenance of cell-cell adhesion junctions, 10,11 a feature that is frequently lost in EMT.…”