Arcuate Na+,K+-ATPase senses systemic energy states and regulates feeding behavior through glucose-inhibited neurons.

Feeding is regulated by perception in the hypothalamus, particularly the first-order arcuate nucleus (ARC) neurons, of the body's energy state. However, the cellular device for converting energy states to the activity of critical neurons in ARC is less defined. We here show that Na(+),K(+)-ATPase (NKA) in ARC senses energy states to regulate feeding.

Antibody engineering and therapeutics, The Annual Meeting of the Antibody Society: December 8-12, 2013, Huntington Beach, CA.

The 24th Antibody Engineering & Therapeutics meeting brought together a broad range of participants who were updated on the latest advances in antibody research and development. Organized by IBC Life Sciences, the gathering is the annual meeting of The Antibody Society, which serves as the scientific sponsor. Preconference workshops on 3D modeling and delineation of clonal lineages were featured, and the conference included sessions on a wide variety of topics relevant to researchers, including systems biology; antibody deep sequencing and repertoires; the effects of antibody gene variation and usage on antibody response; directed evolution; knowledge-based design; antibodies in a complex environment; polyreactive antibodies and polyspecificity; the interface between antibody therapy and cellular immunity in cancer; antibodies in cardiometabolic medicine; antibody pharmacokinetics, distribution and off-target toxicity; optimizing antibody formats for immunotherapy; polyclonals, oligoclonals and bispecifics; antibody discovery platforms; and antibody-drug conjugates.

Concurrent impairment of (Na++K+)-ATPase activity in multi-organ of type-1 diabetic NOD mice.

Background: Type-1 diabetes causes serious complications. Detailed molecular pathways of type-1 diabetes-mediated organ dysfunction are not completely understood. Significantly depressed (Na(+)+K(+))-ATPase (NKA) activity has been found in erythrocytes, pancreatic β-cells, nerve cells, and muscle tissues of type-1 diabetic patients and rodent animal models.

Allosteric property of the (Na⁺+K⁺)-ATPase β₁ subunit.

(Na(+)+K(+))-ATPase (NKA) comprises two basic α and β subunits: The larger α subunit catalyzes the hydrolysis of ATP for active transport of Na(+) and K(+) ions across the plasma membrane; the smaller β subunit does not take part in the catalytic process of the enzyme. Little is known about allosteric regulation of the NKA β subunit. Here, we report a surprising finding that extracellular stimuli on the native β(1) subunit can generate a significant impact on the catalytic function of NKA.

Mechanistic distinction between activation and inhibition of (Na(+)+K(+))-ATPase-mediated Ca2+ influx in cardiomyocytes.

(Na(+)+K(+))-ATPase (NKA) mediates positive inotropy in the heart. Extensive studies have demonstrated that the reverse-mode Na(+)/Ca(2+)-exchanger (NCX) plays a critical role in increasing intracellular Ca(2+) concentration through the inhibition of NKA-induced positive inotropy by cardiac glycosides. Little is known about the nature of the NCX functional mode in the activation of NKA-induced positive inotropy.

Serine496 of β2 subunit of L-type Ca2+ channel participates in molecular crosstalk between activation of (Na++K+)-ATPase and the channel.

Activation of (Na++K+)-ATPase (NKA) regulates cardiac L-type Ca2+ channel (LTCC) function through molecular crosstalk. The mechanism underlying NKA-LTCC crosstalk remains poorly understood. We have previously shown that activation of NKA leads to phosphorylation of LTCC α1 Ser1928.

Activation of (Na+ + K+)-ATPase modulates cardiac L-type Ca2+ channel function.

Cellular Ca(2+) signaling underlies diverse vital biological processes, including muscle contractility, memory encoding, fertilization, cell survival, and cell death. Despite extensive studies, the fundamental control mechanisms that regulate intracellular Ca(2+) movement remain enigmatic. We have found recently that activation of the (Na(+)+K(+))-ATPase markedly potentiates intracellular Ca(2+) transients and contractility of rat heart cells.

Dual activity of the H1-H2 domain of the (Na(+)+K+)-ATPase.

(Na(+)+K(+))-ATPase is a target receptor of digitalis (cardiac glycoside) drugs. It has been demonstrated that the H1-H2 domain of the alpha-subunit of the (Na(+)+K(+))-ATPase is one of the digitalis drug interaction sites of the enzyme. Despite the extensive studies of the inhibitory effect of digitalis on the (Na(+)+K(+))-ATPase, the functional property of the H1-H2 domain of the enzyme and its role in regulating enzyme activity is not completely understood.

Activation of (Na+ + K+)-ATPase induces positive inotropy in intact mouse heart in vivo.

Objective: We have recently identified an activation site on (Na+ + K+)-ATPase and found that binding of antibody SSA412 to this specific site of the enzyme markedly augments (Na+ + K+)-ATPase catalytic activity. Demonstration of whether activation of (Na+ + K+)-ATPase affects heart function in animal in vivo was the object of this investigation.

Methods: Male wild-type CD-1 mouse and specific antibody SSA412 were used for the study.

Activation of (Na+ + K+)-ATPase.

Enzymes catalyze essential chemical reactions needed for living processes. (Na+ +K+)-ATPase (NKA) is one of the key enzymes that control intracellular ion homeostasis and regulate cardiac function. Little is known about activation of NKA and its biological impact.

Dual effects of copper-zinc superoxide dismutase.

Copper-zinc superoxide dismutase (CuZnSOD) specifically catalyzes the removal of superoxide radicals to protect cellular function against the generation of superoxide-dependent hydroxyl radicals ((.)OH). However, an unexpected observation reveals that denatured CuZnSOD (dCuZnSOD) itself induces (.

Evidence that the H1-H2 domain of alpha1 subunit of (Na++K+)-ATPase participates in the regulation of cardiac contraction.

(Na++K+)-ATPase (NKA) plays an important role in ion homeostasis and regulates cardiac contraction. To understand the molecular basis of its cardiac regulatory functions, we investigated whether the primary structure of the H1-H2 domain in alpha-1 (alpha1) subunit of the enzyme plays a role in myocardial contractile regulation. Here we show that site-specific binding to this 1 H1-H2 domain with a targeted antibody (SSA78) markedly augments intracellular Ca2+ transients and contraction of rat ventricular cardiomyocytes without inactivating NKA.

Nitric oxide protects cardiac sarcolemmal membrane enzyme function and ion active transport against ischemia-induced inactivation.

Nitric oxide (NO.) generated from nitric oxide synthase (NOS) isoforms bound to cellular membranes may serve to modulate oxidative stresses in cardiac muscle and thereby regulate the function of key membrane-associated enzymes. Ischemia is known to inhibit the function of sarcolemmal enzymes, including the (Na+ + K+)-ATPase, but it is unknown whether concomitant injury to sarcolemma (SL)-associated NOS isoforms may contribute to this process by reducing the availability of locally generated NO.

Lack of nitric oxide synthase depresses ion transporting enzyme function in cardiac muscle.

Nitric oxide (NO*) is produced endogenously from NOS isoforms bound to sarcolemmal (SL) and sarcoplasmic reticulum (SR) membranes. To investigate whether locally generated NO* directly affects the activity of enzymes mediating ion active transport, we studied whether knockout of selected NOS isoforms would affect the functions of cardiac SL (Na+ + K+)-ATPase and SR Ca2+-ATPase. Cardiac SL and SR vesicles containing either SL (Na+ + K+)-ATPase or SR Ca2+-ATPase were isolated from mice lacking either nNOS or eNOS, or both, and tested for enzyme activities.

Cell surface expression of a specific antigenic site on the catalytic subunit of (Na(+) + K(+))-ATPase.

Structural localization of a peptide region, KRQPRNPKTDKLVNE, in the catalytic subunit of (Na(+) + K(+))-ATPase was investigated using a specific antibody directed against this peptide in cultured African green monkey kidney CV-1 cells. Immunofluorescence staining of frozen cell sections shows that an anti-KRQPRNPKTDKLVNE antibody (SSA95) interacts with its antigenic site and binds to the extracellular side of the cell membrane. Indirect immunofluorescence and flow cytometric analyses confirmed the presence of this epitope on intact cell surfaces.