Thyroid hormone stimulates Na-K-ATPase activity and its plasma membrane insertion in rat alveolar epithelial cells

2003 ◽  
Vol 285 (3) ◽  
pp. L762-L772 ◽  
Author(s):  
Jianxun Lei ◽  
Sogol Nowbar ◽  
Cary N. Mariash ◽  
David H. Ingbar
Keyword(s):  
Plasma Membrane ◽  
Thyroid Hormone ◽  
Atpase Activity ◽  
Cell Lines ◽  
Surface Expression ◽  
Hydrolytic Activity ◽  
Alveolar Epithelial Cells ◽  
Cell Surface Expression ◽  
Alveolar Epithelial ◽  
Adult Rat

Na-K-ATPase protein is critical for maintaining cellular ion gradients and volume and for transepithelial ion transport in kidney and lung. Thyroid hormone, 3,3′,5-triiodo-l-thyronine (T3), given for 2 days to adult rats, increases alveolar fluid resorption by 65%, but the mechanism is undefined. We tested the hypothesis that T3 stimulates Na-K-ATPase in adult rat alveolar epithelial cells (AEC), including primary rat alveolar type II (ATII) cells, and determined mechanisms of the T3 effect on the Na-KATPase enzyme using two adult rat AEC cell lines (MP48 and RLE-6TN). T3 at 10-8 and 10-5 M increased significantly hydrolytic activity of Na-K-ATPase in primary ATII cells and both AEC cell lines. The increased activity was dose dependent in the cell lines (10-9-10-4 M) and was detected within 30 min and peaked at 6 h. Maximal increases in Na-K-ATPase activity were twofold in MP48 and RLE-6TN cells at pharmacological T3 of 10-5 and 10-4 M, respectively, but increases were statistically significant at physiological T3 as low as 10-9 M. This effect was T3 specific, because reverse T3 (3,3′,5′-triiodo-l-thyronine) at 10-9-10-4 M had no effect. The T3-induced increase in Na-K-ATPase hydrolytic activity was not blocked by actinomycin D. No significant change in mRNA and total cell protein levels of Na-K-ATPase were detected with 10-9-10-5 M T3 at 6 h. However, T3 increased cell surface expression of Na-K-ATPase α1- or β1-subunit proteins by 1.7- and 2-fold, respectively, and increases in Na-K-ATPase activity and cell surface expression were abolished by brefeldin A. These data indicate that T3 specifically stimulates Na-K-ATPase activity in adult rat AEC. The upregulation involves translocation of Na-K-ATPase to plasma membrane, not increased gene transcription. These results suggest a novel nontranscriptional mechanism for regulation of Na-K-ATPase by thyroid hormone.

Developmental acquisition of T3-sensitive Na-K-ATPase stimulation by rat alveolar epithelial cells

2007 ◽  
Vol 292 (1) ◽  
pp. L6-L14 ◽  
Author(s):  
Jianxun Lei ◽  
Christine H. Wendt ◽  
Daosheng Fan ◽  
Cary N. Mariash ◽  
David H. Ingbar
Keyword(s):  
Atpase Activity ◽  
Cell Line ◽  
Alveolar Epithelial Cell ◽  
Developmental Regulation ◽  
Fluid Secretion ◽  
Surface Expression ◽  
Alveolar Epithelial Cells ◽  
Cell Surface Expression ◽  
Alveolar Epithelial ◽  
Parallel Increase

Late in gestation, the developing air space epithelium switches from chloride and fluid secretion to sodium and fluid absorption. Absorption requires Na-K-ATPase acting in combination with apical sodium entry mechanisms. Hypothyroidism inhibits perinatal fluid resorption, and thyroid hormone [triiodothyronine (T3)] stimulates adult alveolar epithelial cell (AEC) Na-K-ATPase. This study explored the developmental regulation of Na-K-ATPase by T3 in fetal rat distal lung epithelial (FDLE) cells. T3 increased Na-K-ATPase activity in primary FDLE cells from gestational day 19 [both primary FDLE cells at embryonic day 19 (E19) and the cell line FD19 derived from FDLE cells at E19]. However, T3 did not increase the Na-K-ATPase activity in less mature FDLE cells, including primary E17 and E18 FDLE cells and the cell line FD18 (derived from FDLE cells at E18). Subsequent experiments assessed the T3 signal pathway to define whether it was similar in the late FDLE and adult AEC and to determine the site of the switch in responsiveness to T3. As in adult AEC, in the FD19 cell line, the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin blocked the T3-induced increase in Na-K-ATPase activity and plasma membrane quantity. T3 caused a parallel increase in phosphorylation of Akt at Ser473 in FDLE cells from E19, but not from E17 or E18. In the FD18 cell line, transient expression of a constitutively active mutant of the PI3K catalytic p110 subunit significantly augmented the Na-K-ATPase activity and the cell surface expression of Na-K-ATPase α1 protein. In conclusion, FDLE cells from E17 and E18 lacked T3-sensitive Na-K-ATPase activity but acquired this response at E19. The developmental stimulation of Na-K-ATPase by T3 in rat FDLE cells requires activation of PI3K, and the acquisition of T3 responsiveness may be at PI3K or upstream in the signaling pathway.

scholarly journals Hypoxia and β2-Agonists Regulate Cell Surface Expression of the Epithelial Sodium Channel in Native Alveolar Epithelial Cells

2002 ◽  
Vol 277 (49) ◽  
pp. 47318-47324 ◽  
Author(s):  
Carole Planès ◽  
Marcel Blot-Chabaud ◽  
Michael A. Matthay ◽  
Sylviane Couette ◽  
Tokujiro Uchida ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Surface ◽  
Sodium Channel ◽  
Epithelial Sodium Channel ◽  
Surface Expression ◽  
Alveolar Epithelial Cells ◽  
Cell Surface Expression ◽  
Alveolar Epithelial ◽  
Β2 Agonists

Src kinase integrates PI3K/Akt and MAPK/ERK1/2 pathways in T3-induced Na-K-ATPase activity in adult rat alveolar cells

2011 ◽  
Vol 301 (5) ◽  
pp. L765-L771 ◽  
Author(s):  
Jianxun Lei ◽  
David H. Ingbar
Keyword(s):  
Atpase Activity ◽  
Src Kinase ◽  
Alveolar Epithelial Cells ◽  
Alveolar Type ◽  
Akt Inhibitor ◽  
Alveolar Cells ◽  
Alveolar Epithelial ◽  
Adult Rat ◽  
Constitutively Active Mutants ◽  
Constitutively Active

We previously reported that the 3,5,3′-triiodo-l-thyronine (T3)-induced increase of Na-K-ATPase activity in rat alveolar epithelial cells (AECs) required activation of Src kinase, PI3K, and MAPK/ERK1/2. In the present study, we assessed the role of Akt in Na-K-ATPase activity and the interaction between the PI3K and MAPK in response to T3 by using MP48 cells, inhibitors, and constitutively active mutants in the MP48 (alveolar type II-like) cell line. The Akt inhibitor VIII blocked T3-induced increases in Na-K-ATPase activity and amount of plasma membrane Na-K-ATPase protein. The Akt inhibitor VIII also abolished the increase in Na-K-ATPase activity induced by constitutively active mutants of either Src kinase or PI3K. Moreover, constitutively active mutants of Akt increased Na-K-ATPase activity in the absence of T3. Thus activation of Akt was required for T3-induced Na-K-ATPase activity in AECs and is sufficient in the absence of T3. Inhibitors of Src kinase (PP1), PI3K (wortmannin), and ERK1/2 (U0126) all blocked the T3-induced Na-K-ATPase activity. PP1 blocked the activation of PI3K and also ERK1/2 by T3, whereas U0126 did not prevent T3 activation of Src kinase or PI3K activity. Wortmannin did not significantly alter T3-increased MAPK/ERK1/2 activity, suggesting that T3-activated PI3K/Akt and MAPK/ERK1/2 pathways acted downstream of the Src kinase. Furthermore, in the absence of T3, a constitutively active mutant of Src kinase increased activities of Na-K-ATPase, PI3K, and MAPK/ERK1/2. A constitutively active mutant of PI3K enhanced Na-K-ATPase activity but did not alter the MAPK/ERK1/2 activity significantly. In summary, in adult rat AECs T3-stimulated Src kinase activity can activate both PI3K/Akt and MAPK/ERK1/2, and activation of Akt is necessary for T3-induced Na-K-ATPase activity.

Modeling the effect of stretch and plasma membrane tension on Na+-K+-ATPase activity in alveolar epithelial cells

2007 ◽  
Vol 292 (1) ◽  
pp. L40-L53 ◽  
Author(s):  
Jacob L. Fisher ◽  
Susan S. Margulies
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Atpase Activity ◽  
Alveolar Epithelial Cells ◽  
Cyclic Stretch ◽  
Model Parameters ◽  
Membrane Tension ◽  
Membrane Area ◽  
Whole Cell ◽  
Alveolar Epithelial

While a number of whole cell mechanical models have been proposed, few, if any, have focused on the relationship among plasma membrane tension, plasma membrane unfolding, and plasma membrane expansion and relaxation via lipid insertion. The goal of this communication is to develop such a model to better understand how plasma membrane tension, which we propose stimulates Na+-K+-ATPase activity but possibly also causes cell injury, may be generated in alveolar epithelial cells during mechanical ventilation. Assuming basic relationships between plasma membrane unfolding and tension and lipid insertion as the result of tension, we have captured plasma membrane mechanical responses observed in alveolar epithelial cells: fast deformation during fast cyclic stretch, slower, time-dependent deformation via lipid insertion during tonic stretch, and cell recovery after release from stretch. The model estimates plasma membrane tension and predicts Na+-K+-ATPase activation for a specified cell deformation time course. Model parameters were fit to plasma membrane tension, whole cell capacitance, and plasma membrane area data collected from the literature for osmotically swollen and shrunken cells. Predictions of membrane tension and stretch-stimulated Na+-K+-ATPase activity were validated with measurements from previous studies. As a proof of concept, we demonstrate experimentally that tonic stretch and consequent plasma membrane recruitment can be exploited to condition cells against subsequent cyclic stretch and hence mitigate stretch-induced responses, including stretch-induced cell death and stretch-induced modulation of Na+-K+-ATPase activity. Finally, the model was exercised to evaluate plasma membrane tension and potential Na+-K+-ATPase stimulation for an assortment of traditional and novel ventilation techniques.

scholarly journals Analysis of Na+,K+-ATPase Motion and Incorporation into the Plasma Membrane in Response to G Protein–coupled Receptor Signals in Living Cells

2003 ◽  
Vol 14 (3) ◽  
pp. 1149-1157 ◽  
Author(s):  
Alejandro M. Bertorello ◽  
Yulia Komarova ◽  
Kristen Smith ◽  
Ingo B. Leibiger ◽  
Riad Efendiev ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Fluorescent Protein ◽  
Alveolar Epithelial Cells ◽  
Alveolar Cells ◽  
Α Subunit ◽  
Alveolar Epithelial ◽  
Major Mechanism ◽  
Directional Movement ◽  
Green Fluorescent

Dopamine (DA) increases Na+,K+-ATPase activity in lung alveolar epithelial cells. This effect is associated with an increase in Na+,K+-ATPase molecules within the plasma membrane ( Ridge et al., 2002 ). Analysis of Na+,K+-ATPase motion was performed in real-time in alveolar cells stably expressing Na+,K+-ATPase molecules carrying a fluorescent tag (green fluorescent protein) in the α-subunit. The data demonstrate a distinct (random walk) pattern of basal movement of Na+,K+-ATPase–containing vesicles in nontreated cells. DA increased the directional movement (by 3.5 fold) of the vesicles and an increase in their velocity (by 25%) that consequently promoted the incorporation of vesicles into the plasma membrane. The movement of Na+,K+-ATPase–containing vesicles and incorporation into the plasma membrane were microtubule dependent, and disruption of this network perturbed vesicle motion toward the plasma membrane and prevented the increase in the Na+,K+-ATPase activity induced by DA. Thus, recruitment of new Na+,K+-ATPase molecules into the plasma membrane appears to be a major mechanism by which dopamine increases total cell Na+,K+-ATPase activity.

scholarly journals Isolation of Chinese hamster ovary cell lines temperature conditional for the cell-surface expression of integral membrane glycoproteins.

1989 ◽  
Vol 108 (2) ◽  
pp. 339-353 ◽  
Author(s):  
J Hearing ◽  
E Hunter ◽  
L Rodgers ◽  
M J Gething ◽  
J Sambrook
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Cell Lines ◽  
Chinese Hamster Ovary ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Surface Expression ◽  
Ovary Cell ◽  
Cell Surface Expression ◽  
Membrane Glycoproteins

A procedure is described to select mutants of Chinese hamster ovary cells that are conditionally defective for the cell-surface expression of integral membrane glycoproteins, including the hemagglutinin (HA) of influenza virus. Using a combination of cell sorting and biochemical screening, seven cell lines were obtained that express more cell-surface HA at 32 degrees C than at 39 degrees C. The production of infectious vesicular stomatitis virus, whose growth requires insertion of an integral membrane protein into the plasma membrane, was also temperature conditional in the majority of these mutant cell lines. Five of the lines synthesized apparently normally core-glycosylated HA at the elevated temperature but the protein was neither displayed on the cell surface nor accumulated intracellularly. In these cell lines, little or no terminally glycosylated HA molecules were observed after synthesis at 39 degrees C. By contrast, the core glycosylation of HA and several other integral membrane proteins was abnormal in the remaining two cell lines at both permissive and restrictive temperatures, due to a lesion in a cellular gene(s) that affects the formation of and/or the addition of mannose-rich oligosaccharide chains to newly synthesized polypeptides. Although HA was transported to the plasma membrane at both 32 and 39 degrees C, it did not accumulate on the cell surface at the higher temperature, apparently because of an increased rate of degradation.

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