One long term objective is to understand the biochemical and cellular mechanisms of the regulation of the sodium pump (Na,K-ATPase), which is the driving force for cerebrospinal fluid (CSF) secretion. The other is to understand how that regulation is coordinated with the unique morphological changes in the secretory epithelium. We have data that indicate that phosphorylation events at the apical membrane coordinate the regulation of Na,K-ATPase with the regulation of secretory cell morphology. CSF is produced by the choroid plexuses in the brain's ventricles, and it flows out through other structures. Clinically when the outflow pathways are blocked, hydrocephalus (infants) or intracranial hypertension (adults) results. There are endogenous mechanisms that reduce Na,K-ATPase activity in the choroid plexus that we will investigate, including thirst, vasopressin, serotonin, and carbachol. The proposed research has three complementary thrusts.
The first aim uses the tools of biochemistry, primary cultures, and genetic manipulation of cells to test the hypothesis that choroid plexus Na,K-ATPase is regulated by kinase-mediated phosphorylation of an accessory protein, phospholemman (FXYD1), with a change in the kinetics of the enzyme. Comparison of cultures from wild type and phospholemman knockout mice will allow direct and indirect effects to be separated.
The second aim uses the tools of microscopy and biochemistry to investigate whether the regulation entails redistribution from microvilli to a subapical compartment.
The third aim uses wild type, phospholemman knockout, and hydrocephalic mice to test the hypothesis that phospholemman is an obligatory link to regulation of both Na,K-ATPase and choroid cell activation state.
The aims test several hypotheses: 1) that there is concerted regulation of Na,K-ATPase and morphological change at the apical brush border through macromolecular complexes; 2) that the phospholemman knockout mouse has defective responses to physiological signals to inhibit Na,K-ATPase and change choroid cell morphology; and 3) that a mouse strain that develops hydrocephalus shows enhanced phospholemman phosphorylation, increased cell morphology changes, and reductions in Na,K-ATPase. Relevance: A better understanding of these basic mechanisms in the CSF-secreting organ is needed to facilitate new discoveries of ways to reduce CSF secretion, either to replace surgical shunts or to at least stabilize fragile infants prior to surgery. ? ?

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
Program Officer
Talley, Edmund M
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Massachusetts General Hospital
United States
Zip Code
Arystarkhova, Elena; Sweadner, Kathleen J (2016) Functional Studies of Na(+),K(+)-ATPase Using Transfected Cell Cultures. Methods Mol Biol 1377:321-32
Sweadner, Kathleen J (2016) Colorimetric Assays of Na,K-ATPase. Methods Mol Biol 1377:89-104
Arystarkhova, Elena (2016) Beneficial Renal and Pancreatic Phenotypes in a Mouse Deficient in FXYD2 Regulatory Subunit of Na,K-ATPase. Front Physiol 7:88
Arystarkhova, Elena; Liu, Yi B; Salazar, Cynthia et al. (2013) Hyperplasia of pancreatic beta cells and improved glucose tolerance in mice deficient in the FXYD2 subunit of Na,K-ATPase. J Biol Chem 288:7077-85
Brashear, Allison; Cook, Jared F; Hill, Deborah F et al. (2012) Psychiatric disorders in rapid-onset dystonia-parkinsonism. Neurology 79:1168-73
Barbano, Richard L; Hill, Deborah F; Snively, Beverly M et al. (2012) New triggers and non-motor findings in a family with rapid-onset dystonia-parkinsonism. Parkinsonism Relat Disord 18:737-41
Bibert, St├ęphanie; Liu, Chia-Chi; Figtree, Gemma A et al. (2011) FXYD proteins reverse inhibition of the Na+-K+ pump mediated by glutathionylation of its beta1 subunit. J Biol Chem 286:18562-72
Sweadner, Kathleen J; Pascoa, Jennifer L; Salazar, Cynthia A et al. (2011) Post-transcriptional control of Na,K-ATPase activity and cell growth by a splice variant of FXYD2 protein with modified mRNA. J Biol Chem 286:18290-300