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Comparative Biochemistry and... 1991
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Hypertension (Dallas, Tex. : 1979) Oct 2014
Review
Topics: Animals; Blood Pressure; Humans; Immunoassay; Ouabain; Sodium-Potassium-Exchanging ATPase
PubMed: 25001271
DOI: 10.1161/HYPERTENSIONAHA.114.03919 -
The Clinical Investigator Sep 1994
Review
Topics: Cardiovascular Diseases; Humans; Ion Transport; Ouabain
PubMed: 7849453
DOI: 10.1007/BF00212996 -
Cell Communication and Signaling : CCS Oct 2023Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by an accumulation of immature leukemic myeloblasts initiating from leukemic stem...
BACKGROUND
Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by an accumulation of immature leukemic myeloblasts initiating from leukemic stem cells (LSCs)-the subpopulation that is also considered the root cause of chemotherapy resistance. Repurposing cardiac glycosides to treat cancers has gained increasing attention and supporting evidence, but how cardiac glycosides effectively target LSCs, e.g., whether it involves cell differentiation, remains largely unexplored.
METHODS
Digoxin, a user-designed digitoxigenin-α-L-rhamnoside (D6-MA), and ouabain were tested against various human AML-derived cells with different maturation phenotypes. Herein, we established two study models to specifically determine the effects of cardiac glycosides on LSC death and differentiation-one allowed change in dynamics of LSCs and leukemic progenitor cells (LPCs), while another maintained their undifferentiated status. Regulatory mechanisms underlying cardiac glycoside-induced cytotoxicity were investigated and linked to cell cycle distribution and apoptotic machinery.
RESULTS
Primitive AML cells containing CD34 LSCs/LPCs were very responsive to nanomolar concentrations of cardiac glycosides, with ouabain showing the greatest efficiency. Ouabain preferentially induces caspase-dependent apoptosis in LSCs, independent of its cell differentiation status, as evidenced by (i) the tremendous induction of apoptosis by ouabain in AML cells that acquired less than 15% differentiation and (ii) the higher rate of apoptosis in enriched LSCs than in LPCs. We sorted LSCs and LPCs according to their cell cycle distribution into G0/G1, S, and G2/M cells and revealed that G0/G1 cells in LSCs, which was its major subpopulation, were the top ouabain responders, indicating that the difference in ouabain sensitivity between LSCs and LPCs involved both distinct cell cycle distribution and intrinsic apoptosis regulatory mechanisms. Further, Mcl-1 and c-Myc, which were differentially expressed in LSCs and LPCs, were found to be the key apoptosis mediators that determined ouabain sensitivity in AML cells. Ouabain induces a more rapid loss of Mcl-1 and c-Myc in LSCs than in LPCs via the mechanisms that in part involve an inhibition of Mcl-1 protein synthesis and an induction of c-Myc degradation.
CONCLUSIONS
Our data provide new insight for repurposing cardiac glycosides for the treatment of relapsed/refractory AML through targeting LSCs via distinct cell cycle and apoptosis machinery. Video Abstract.
Topics: Humans; Cardiac Glycosides; Ouabain; Myeloid Cell Leukemia Sequence 1 Protein; Leukemia, Myeloid, Acute; Cell Differentiation; Stem Cells; Neoplastic Stem Cells; Apoptosis
PubMed: 37828578
DOI: 10.1186/s12964-023-01317-8 -
Neurochemical Research Mar 2022Ouabain is a classic NaKATPase ligand and it has been described to have neuroprotective effects on neurons and glial cells at nanomolar concentrations. In the present...
Ouabain-Na/K-ATPase Signaling Regulates Retinal Neuroinflammation and ROS Production Preventing Neuronal Death by an Autophagy-Dependent Mechanism Following Optic Nerve Axotomy In Vitro.
Ouabain is a classic NaKATPase ligand and it has been described to have neuroprotective effects on neurons and glial cells at nanomolar concentrations. In the present work, the neuroprotective and immunomodulatory potential of ouabain was evaluated in neonatal rat retinal cells using an optic nerve axotomy model in vitro. After axotomy, cultured retinal cells were treated with ouabain (3 nM) at different periods. The levels of important inflammatory receptors in the retina such as TNFR1/2, TLR4, and CD14 were analyzed. We observed that TNFR1, TLR4, and CD14 were decreased in all tested periods (15 min, 45 min, 24 h, and 48 h). On the other hand, TNFR2 was increased after 24 h, suggesting an anti-inflammatory potential for ouabain. Moreover, we showed that ouabain also decreased Iba-1 (microglial marker) density. Subsequently, analyses of retrograde labeling of retinal ganglion cells (RGC) were performed after 48 h and showed that ouabain-induced RGC survival depends on autophagy. Using an autophagy inhibitor (3-methyladenine), we observed a complete blockage of the ouabain effect. Western blot analyses showed that ouabain increases the levels of autophagy proteins (LC3 and Beclin-1) coupled to p-CREB transcription factor and leads to autophagosome formation. Additionally, we found that the ratio of cleaved/pro-caspase-3 did not change after ouabain treatment; however, p-JNK density was enhanced. Also, ouabain decreased reactive oxygen species production immediately after axotomy. Taken together, our results suggest that ouabain controls neuroinflammation in the retina following optic nerve axotomy and promotes RGC neuroprotection through activation of the autophagy pathway.
Topics: Adenosine Triphosphatases; Animals; Autophagy; Axotomy; Cell Survival; Neuroinflammatory Diseases; Optic Nerve; Ouabain; Rats; Reactive Oxygen Species; Retina
PubMed: 34783975
DOI: 10.1007/s11064-021-03481-0 -
General Pharmacology Oct 19981. Ouabain or a related stereoisomer, termed endogenous ouabain, has been identified in adrenal cortex tissue and culture medium from adrenocortical cells. 2.... (Review)
Review
1. Ouabain or a related stereoisomer, termed endogenous ouabain, has been identified in adrenal cortex tissue and culture medium from adrenocortical cells. 2. Angiotensin II and adrenocorticotropin, the main activators of aldosterone secretion from adrenal glomerulosa cells appear to increase the production of this compound. 3. The purpose of this review is to briefly discuss recent available experimental evidence suggesting that endogenous ouabain is secreted by the zona glomerulosa of the adrenal gland.
Topics: Adrenal Cortex; Animals; Calcium-Transporting ATPases; Humans; Ouabain; Sodium-Calcium Exchanger; Zona Glomerulosa
PubMed: 9792206
DOI: 10.1016/s0306-3623(98)00021-4 -
Experimental and Clinical Endocrinology... 2000Ouabain has been isolated and identified as a constituent of human blood, bovine adrenal glands and hypothalamus. This water soluble inhibitor of the sodium pump... (Review)
Review
Ouabain has been isolated and identified as a constituent of human blood, bovine adrenal glands and hypothalamus. This water soluble inhibitor of the sodium pump (Na+/K+-ATPase) circulates in elevated concentrations in blood plasma of 50% of Caucasians with elevated blood pressure. It is released from adrenal cortical cells in tissue culture by angiotensin II. A ouabain antagonist, PST2238, lowers blood pressure in hypertensive rats. Hence, ouabain is most probably a new steroid hormone formed in adrenal glands and hypothalamus. Consistent therewith is the demonstration of a specific binding globulin for cardiac glycosides in blood plasma.
Topics: Adrenal Cortex; Adrenal Glands; Animals; Blood Pressure; Cattle; Hormones; Humans; Hypertension; Hypothalamus; Ouabain; Rats; White People
PubMed: 11083065
DOI: 10.1055/s-2000-8140 -
Cell and Tissue Research Sep 2021The sperm-derived oocyte activating factor, phospholipase C zeta (PLC ζ), is the only PLC isoform reported in cattle. The objectives were to (1) localize PLC ζ in...
The sperm-derived oocyte activating factor, phospholipase C zeta (PLC ζ), is the only PLC isoform reported in cattle. The objectives were to (1) localize PLC ζ in fresh and capacitated bovine sperm and (2) investigate the activation of PLC ζ during bull sperm capacitation and contributions of PLC activity to this process. We confirmed interaction of testis-specific isoform of Na/K-ATPase (ATP1A4) with PLC ζ (immunolocalization and immunoprecipitation) and tyrosine phosphorylation (immunoprecipitation) of PLC ζ (a post-translational protein modification commonly involved in activation of PLC in somatic cells) during capacitation. Furthermore, incubation of sperm under capacitating conditions upregulated PLC-mediated hyperactivated motility, tyrosine phosphoprotein content, acrosome reaction, and F-actin formation (flow cytometry), implying that PLC activity is enhanced during capacitation and contributing to these capacitation processes. In conclusion, we inferred that PLC ζ is activated during capacitation by tyrosine phosphorylation through a mechanism involving ATP1A4, contributing to capacitation-associated biochemical events.
Topics: Animals; Cattle; Male; Ouabain; Sperm Capacitation; Type C Phospholipases
PubMed: 33885964
DOI: 10.1007/s00441-021-03455-2 -
Theriogenology Mar 2019The endogenous steroid hormone ouabain induces capacitation of bull sperm acting through its receptor Na/K-ATPase on the sperm plasma membrane. Progesterone (P4) is...
The endogenous steroid hormone ouabain induces capacitation of bull sperm acting through its receptor Na/K-ATPase on the sperm plasma membrane. Progesterone (P4) is believed to act through the sperm membrane P4 receptor (mPR) to induce non-genomic signalling leading to capacitation and/or acrosome reaction (AR) in the sperm of some species, but the exact nature of this receptor molecule on bull sperm is not known. In amphibian oocytes, P4 acts through the low-affinity ouabain binding site on Na/K-ATPase to induce signalling highly reminiscent of ouabain's signalling that initiates capacitation. This study hypothesized that ouabain and P4 interact agonistically or antagonistically to induce bull sperm capacitation. Sperm were incubated with 0, 12.5, 25, 50 and 100 μM ouabain, P4 or ouabain + P4 (12.5, 25 and 50 μM each) under capacitating conditions, and capacitation was assessed microscopically looking at the acrosome status of sperm and as the amount of protein tyrosine phosphorylation (Tyr-P). Both steroids stimulated Tyr-P of certain sperm proteins, but ouabain caused tyrosine phosphorylation of more proteins than P4 and stimulated significantly more overall Tyr-P (P < 0.05). Ouabain also was the only steroid to stimulate significant microscopically-evident AR. When sperm were co-incubated with the two steroids, P4 partially inhibited ouabain-induced Tyr-P and AR. These results suggest that P4 and ouabain may both interact with Na/K-ATPase, but ouabain is the more effective hormone. Ouabain may, therefore, be the primary physiological inducer of bovine capacitation.
Topics: Animals; Cattle; Male; Ouabain; Phosphorylation; Progesterone; Sperm Capacitation; Tyrosine
PubMed: 30572274
DOI: 10.1016/j.theriogenology.2018.12.003 -
Kidney International Jun 1996Substantial evidence implicates impaired renal excretion of sodium as the major culprit in the pathogenesis of hypertension. The key question is: How does the impairment... (Review)
Review
Substantial evidence implicates impaired renal excretion of sodium as the major culprit in the pathogenesis of hypertension. The key question is: How does the impairment of Na+ excretion lead to increased peripheral vascular resistance and elevation of the blood pressure? Here we describe the evidence that elevated levels of a recently-discovered adrenal cortical hormone, endogenous ouabain, plays a central role in this process. This hormone inhibits the Na+ pump and raises intracellular Na+. Then, as a result of Na/Ca exchange, cytosolic Ca2+ and, more importantly, intracellular stores of Ca2+, are increased in vascular smooth muscle (VSM), vasomotor neurons, and endothelial cells, as well as in many other types of cells. Consequently, these cells become hyper-responsive because the cytosolic Ca2+ transients induced by cell activation are enhanced. The synergy of augmented sympathetic neuron transmitter release and augmented VSM cell responsiveness may account for the increased arterial tone and peripheral vascular resistance that is the hallmark of hypertension.
Topics: Animals; Hypertension; Ouabain
PubMed: 8743490
DOI: 10.1038/ki.1996.260