Na,K-ATPase pump in activated human lymphocytes: on the mechanisms of rapid and long-term increase in K influxes during the initiation of phytohemagglutinin-induced proliferation

Abstract

Functional expression of Na, K-ATPase pump as determined by ouabain-sensitive Rb influxes has been investigated in human peripheral blood lymphocytes, activated by phytohemagglutinin (PHA) from resting state to proliferation. It is found that a rapid twofold elevation of ouabain-sensitive Rb influx in response to PHA is followed by a long-term increase in pump activity, which precedes the DNA synthesis and is temporally related to the growth phase of mitogenic response. Unlike the early pump activation, the late enhanced pump activity is not the result of elevated cell Na content, it is inhibited by cycloheximide and requires new protein synthesis. Actinomycin D and alpha-amanitin, in doses, which suppress the PHA-induced increase in the RNA synthesis, do not abolish the elevated Rb influx until 20-24h of mitogenic activation and inhibit the late, growth-associated increase in Rb influx. It is concluded that (1) in mitogen-activated cells both short- and long-term control is involved in the enhanced pump activity, and (2) translational and transcriptional mechanisms may contribute to the long-term up-regulation of Na, K-ATPase pump during blast transformation of human lymphocytes.

Association of ATP1A1 and Dear Single-Nucleotide Polymorphism Haplotypes With Essential Hypertension

“…Coexpression of both hypertension susceptibility variants in cell types implicated in BP regulation, such as endothelium and renal tubular epithelium, suggest a unifying hypothesis that polygenic expression convergence of multiple hypertension susceptibility gene variants on the same cellular target acts as a pathogenic scaffold for polygenic hypertension mechanisms. Intuitively, altered ATP1A1 and Dear functions in endothelium could contribute, in combination, to endothelial dysfunction through a putative imbalance of endothelial repair to turnover, because ATP1A1 is implicated in cell proliferation 24,25 and Dear in angiogenesis, 9 the latter involving endothelial cell proliferation, migration, and survival. 26 Likewise, ATP1A1 and Dear in renal tubular epithelial cells could affect sodium homeostasis, because ET-1 decreases renal Na,KATPase activity.…”

Differential Transcription of Ion Transporters, NHE1, ATP1B1, NKCC1 in Human Peripheral Blood Lymphocytes Activated to Proliferation

“…The next day the cell suspension was made up to a concentration of (1.5-2)·10 6 cells/mL, placed in vials (10-20 mL/vial), and PHA-M (Calbiochem or Sigma) was added to a final concentration of 10-20 µg/mL. Thereafter, the lymphocyte cultures were incubated for 4, 8, 12, 24, or 48 h. To assess the degree of cell activation, parallel cultures of lymphocytes from the same donor were pulsed for 30 min with 3 [H]thymidine, 14 [C]leucine, and 3 [H]uridine at 37°C with 5% CO 2 , and radioactivity of cell TCA precipitates dissolved in 0.1 N NaOH was counted in a liquid scintillation counter as described previously [6][7][8].…”

Plasma Membrane Depolarization without Repolarization Is an Early Molecular Event in Anti-Fas-induced Apoptosis

“…The occurrence of complete cellular depolarization in the presence of ouabain alone without a major enhancement of degraded DNA suggests that increased PMP alone is not by itself a sufficient activator of apoptosis but rather is necessary for cell death. To substantiate these inhibitor studies, we examined the functional expression of the Na ϩ /K ϩ -ATPase during apoptosis using a well established ouabain-sensitive uptake of Rb ϩ assay (31)(32)(33). Total Rb ϩ uptake along with the Rb ϩ fraction that was ouabain-insensitive were measured in both control and anti-Fas-treated Jurkat cells (Fig.…”