Project description:Whole hearts from wild-type and Na,K-ATPase alpha 1 het. mice. Adult male, 8-16 weeks old on a 129/BSwiss background. Keywords: repeat sample
Project description:Familial hemiplegic migraine is an episodic neurological disorder characterized by transient sensory and motor symptoms and signs. Mutations of the ion pump alpha2-Na/K ATPase represent a key genetic cause of familial hemiplegic migraine, but the mechanisms by which alpha2-Na/K ATPase mutations lead to the migraine phenotype remain incompletely understood. Here, we unexpectedly find that mice in which alpha2-Na/K ATPase is conditionally deleted in astrocytes display episodic transient motor paralysis. Functional neuroimaging reveals that conditional knockout of alpha2-Na/K ATPase triggers spontaneous cortical spreading depression events that are associated with low voltage activity events upon EEG monitoring, which in turn correlate with transient motor impairment in these mice. Transcriptomic and metabolomic analyses show that loss of alpha2-Na/K ATPase alters metabolic gene expression in astrocytes in vivo with consequent elevation of serine and glycine in the brain. Strikingly, feeding alpha2-Na/K ATPase knockout mice a serine- and glycine-free diet reverses the phenotype of transient motor impairment. Together, our findings define a novel metabolic mechanism regulated by astrocytic alpha2-Na/K ATPase that triggers episodic transient motor paralysis in mice, laying the foundation for potential new treatment strategies for patients with familial hemiplegic migraine.
Project description:Exposure to hypoxia requires adaptive mechanisms for survival. During acute hypoxia, Na,K-ATPase endocytosis in alveolar epithelial cells (AEC) occurs via protein kinase C zeta (PKCζ) phosphorylation of α1- Na,K-ATPase independently of the hypoxia inducible factor (HIF). However, exaggerated Na,K-ATPase down-regulation leads to cell death. Here we report that during prolonged hypoxia plasma membrane Na,K-ATPase levels were maintained at ~50% of normoxic values due to HIF mediated regulation of HOIL-1L which targets PKCζ for degradation. Silencing HOIL-1L in the lung epithelium prevented PKCζ degradation causing Na,K-ATPase downregulation. Accordingly, HIF regulation of HOIL-1L targets the phosphorylated PKCζ for degradation and serves as an hypoxia-adaptive mechanism to stabilize the Na,K-ATPase avoiding significant lung injury.
Project description:The Na/K-ATPase is the specific receptor for cardiotonic steroids (CTS) such as ouabain and digoxin. At pharmacological concentrations used in the treatment of cardiac conditions, CTS inhibit the ion-pumping function of Na/K-ATPase. At much lower concentrations, in the range of those reported for endogenous CTS in the blood, they stimulate hypertrophic growth of cultured cardiac myocytes through initiation of a Na/K-ATPase-mediated and reactive oxygen species (ROS)-dependent signaling. To examine a possible effect of endogenous concentrations of CTS on cardiac structure and function in vivo, we compared mice expressing the naturally resistant Na/K-ATPase α1 and age-matched mice genetically engineered to express a mutated Na/K-ATPase α1 with high affinity for CTS. In this model, total cardiac Na/K-ATPase activity, α1, α2 and β1 protein content remained unchanged, and the cardiac Na/K-ATPase dose-response curve to ouabain shifted to the left as expected. In males aged 3–6 months, increased α1 sensitivity to CTS resulted in a significant increase of cardiac carbonylated protein content, suggesting that ROS production was elevated. A moderate but significant increase of about 15% of the heart-weight-to-tibia-length ratio, accompanied by an increase of myocyte cross-sectional area was detected. Echocardiographic analyses did not reveal any change in cardiac function, and there was no fibrosis or re-expression of the fetal gene program. RNA sequencing analysis indicated that pathways related to energy metabolism were upregulated, while those related to extracellular matrix organization were downregulated. Consistent with a functional role of the latter, an angiotensin-II challenge that triggered fibrosis in the α1r/rα2s/s mouse failed to do so in the α1s/sα2s/s. Taken together, these results are indicative of a link between circulating CTS, Na/K-ATPase α1, ROS, and physiological cardiac hypertrophy in mice under baseline laboratory conditions.
Project description:The cancer-killing activity of T cells is often compromised within tumors, allowing disease progression. We previously found that intratumoral elevations in extracellular K+ constrain T cell antitumor function. Despite the relevance of K+abundance for T cell antitumor function and the importance of ion gradients for cellular physiology broadly, our understanding of T cell K+ transporters remains rudimentary7,8. Here, we report that the Na+-K+-ATPase is required for T cell quiescence, memory formation, and antitumor activity. Deletion of Atp1a1, the catalytic alpha subunit of the Na+-K+-ATPase, in CD8+ T cells induced constitutive activity in TCR, Akt-mTOR, and MAPK/ Erk signaling pathways. This state of tonic signal transduction was reflected in the acquisition of co-inhibitory surface receptors and terminal differentiation in T cells following Atp1a1 deletion. Mechanistically, we found that the Na+-K+-ATPase functions to support ROS homeostasis as its disruption produced ROS accumulation and the addition of antioxidants prevented the accelerated differentiation and acquisition of co-inhibitory receptors in T cells lacking Atp1a1. The in vivo behavior of T cells lacking Atp1a1 was also consistent with tonic signal transduction and stimulation-induced terminal differentiation. T cells lacking Atp1a1 could not achieve proliferative burst or form memory following pathogen challenge or perform tumor destruction in a syngeneic model of orthotopic murine melanoma. These results highlight the fundamental but underappreciated importance of monovalent ion transporters in T cell biology and have translational implications for the ongoing development of immune checkpoint blockade and T cell transfer therapies (i.e. CAR, TCR, TIL).
Project description:Recent genetic evidence implicates the serine/threonine kinase cyclin G-associated kinase (GAK) as a Parkinson’s disease risk. However, its role in neuronal function and many downstream effectors remain unclear. Employing a chemical genetics method, we show here that the sodium potassium pump (Na+/K+-ATPase) is a GAK target in the brain. We further show that GAK modulates Na+/K+-ATPase at a novel site affecting both pump localization and function. Whole-cell patch clamp recordings from CA1 pyramidal cells in GAK conditional knockout mice show a larger change in resting membrane potential when exposed to the Na+/K+-ATPase blocker, ouabain, indicating altered Na+/K+-ATPase function in GAK knockouts. Additionally, we show that GAK-deficient neurons have enlarged dendritic spines and we identify the spine associated protein Sipa1L1 (or SPAR) as a GAK target, which may contribute to this effect. Our results reveal novel functions of GAK in neurons.
Project description:Background. Mutations in ATP1A2 gene encoding the Na,K-ATPase α2 isoform is associated with familial hemiplegic migraine type 2 (FHM2). Migraine with aura is a known risk factor for heart disease. The Na,K-ATPase is important for cardiac function but its role for heart disease remains unknown. We hypothesized that ATP1A2 is a susceptibility gene for heart disease and aimed to assess the underlying disease mechanism. Methods and Results. Mice heterozygous for the FHM2-associated G301R mutation in the Atp1a2 gene (α2+/G301R mice) and matching wild type (WT) controls were compared. Reduced expression of the Na,K-ATPase α2 isoform and increased expression of the α1 isoform was observed in hearts from α2+/G301R mice (Western blot). Left ventricular dilation and reduced ejection fraction was shown in hearts from 8-month-old α2+/G301R mice (cardiac magnetic resonance imaging) and this was associated with reduced nocturnal blood pressure (radiotelemetry). Cardiac function and blood pressure of 3-month-old α2+/G301R mice were similar to WT mice. Amplified Na,K-ATPase-dependent Src/Ras/Erk1/2 signaling was observed in hearts from 8-month-old α2+/G301R mice and this was associated with mitochondrial uncoupling (respirometry), increased oxidative stress (malonedialdehyde measurements), and a heart failure-associated metabolic shift (hyperpolarized magnetic resonance). Mitochondrial membrane potential was similar between the groups (JC-1 dye assay). Proteomics of heart tissue further suggested amplified Src/Ras/Erk1/2 signaling and increased oxidative stress and provided the molecular basis for systolic dysfunction in 8-month-old α2+/G301R mice. Conclusions. Our findings suggest that ATP1A2 mutation leads to disturbed cardiac metabolism and reduced cardiac function mediated via Na,K-ATPase-dependent ROS signaling through the Src/Ras/Erk1/2 pathway.
Project description:Background: Acute respiratory distress syndrome (ARDS) is characterized by refractory hypoxemia caused by accumulation of pulmonary fluid, which is related to inflammatory cell infiltration, impaired tight junction of pulmonary epithelium and impaired Na, K-ATPase function, especially Na, K-ATPase α1 subunit. Up until now, the pathogenic mechanism at the level of protein during lipopolysaccharide- (LPS-) induced ARDS remains unclear. Methods: Using an unbiased, discovery and quantitative proteomic approach, we discovered the differentially expressed proteins binding to Na, K-ATPase α1 between LPS-A549 cells and Control-A549 cells. These Na, K-ATPase α1 interacting proteins were screened by co-immunoprecipitation (Co-IP) technology. Among them, some of the differentially expressed proteins with significant performance were identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The protein interaction network was constructed by the related Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Several differentially expressed proteins were validated by Western blot. Results: Of identified 1598 proteins, 89 were differentially expressed proteins between LPS-A549 cells and Control-A549 cells. Intriguingly, protein-protein interaction network showed that there were 244 significantly enriched co-expression among 60 proteins in the group control-A549. while the group LPS-A549 showed 43 significant enriched interactions among 29 proteins. The related GO and KEGG analysis found evident phenomena of ubiquitination and deubiquitination, as well as the pathways related to autophagy. Among proteins with rich abundance, there were several intriguing ones, including the deubiquitinase (OTUB1), the tight junction protein zonula occludens-1 (ZO-1), the scaffold protein in CUL4B-RING ubiquitin ligase (CRL4B) complexes (CUL4B) and the autophagy-related protein sequestosome-1 (SQSTM1). Conclusions: In conclusion, our proteomic approach revealed targets related to the occurrence and development of ARDS, being the first study to investigate significant differences in Na, K-ATPase α1 interacting proteins between LPS-induced ARDS cell model and control-A549 cell. These proteins may help the clinical diagnosis and facilitate the personalized treatment of ARDS.