Lung epithelial Na channel subunits are differentially regulated during development and by steroids

1995 ◽  
Vol 269 (3) ◽  
pp. C805-C812 ◽  
Author(s):  
S. Tchepichev ◽  
J. Ueda ◽  
C. Canessa ◽  
B. C. Rossier ◽  
H. O'Brodovich
Keyword(s):  
Fetal Lung ◽  
Developmental Expression ◽  
Na Channel ◽  
Mrna Levels ◽  
Adult Rats ◽  
Pregnant Rats ◽  
Lung Epithelial ◽  
Normal Rat ◽  
Epithelial Na Channel

Because the alpha-subunit of the rat lung epithelial Na channel (rENaC) is not expressed until late fetal gestation, the developmental immaturity of alpha-rENaC may be involved in the premature fetal lung's inability to mount a Na-absorptive response to appropriate agonists. As previous work has shown that the beta- and gamma-rENaC subunits of the Na channel are required for maximal alpha-rENaC activity, we determined their developmental expression in the fetal lung. In addition, because thyroid and corticosteroid therapy can mature the in vivo fetal lamb lung's ability to transport Na, we wished to determine whether such treatment increased the expression of alpha-, beta-, and gamma-rENaC. Lungs were harvested from normal rat fetuses of 17 through 22 days gestation (term = 22 days), normal rat pups during the first week of life, and adult rats. Initial expression of alpha-rENaC was detected at 19 days gestation and progressively increased in utero. beta- and gamma-rENaC mRNA were not detected until 21 and 22 days gestation, and then only at very low levels. During the first week after birth, the levels of alpha-rENaC declined, whereas beta- and gamma-rENaC mRNA levels increased. This pre- and postnatal pattern of alpha-rENaC expression correlates with the endogenous glucocorticosteroid levels in the fetus and the rat pup's early postnatal corticosteroid resistance. Combined or separate treatment of pregnant rats (16 through 22 days gestational age) with thyroid-releasing hormone (TRH) and/or dexamethasone (Dex) for 48 h showed that Dex, but not TRH, could increase fetal lung alpha-rENaC mRNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the epithelial Na+ channel in the developing rat lung

1993 ◽  
Vol 265 (2) ◽  
pp. C491-C496 ◽  
Author(s):  
H. O'Brodovich ◽  
C. Canessa ◽  
J. Ueda ◽  
B. Rafii ◽  
B. C. Rossier ◽  
...  
Keyword(s):  
Primary Cultures ◽  
Alveolar Epithelium ◽  
Fetal Lung ◽  
Na Channel ◽  
Mrna Levels ◽  
Rat Lung ◽  
Na Transport ◽  
Pregnant Rats ◽  
Adult Rat ◽  
Epithelial Na Channel

The adult mature fetal, but not immature fetal, lung is capable of actively transporting Na+ from the alveolar space. The reason for the impaired Na+ transport in the immature lung is not known; however, the apical membrane Na+ channel is the rate-limiting step for epithelial Na+ transport. This study determined whether transcripts coding for the adult rat colonic epithelial Na+ channel (alpha rENaC) were present in the fetal and adult lung and whether they were developmentally regulated. Similarly sized alpha rENaC transcripts were identified in RNA isolated from fetal and adult whole rat lung, primary cultures of fetal and adult alveolar epithelium, and adult rat whole kidneys, suggesting that the lung alpha rENaC is a similar transcript to that found in the salt-deprived rat colonic epithelium. There were low mRNA levels in 17- to 18-day gestational age (GA) fetal lungs and epithelium (term GA = 22 days), but these levels increased markedly during the saccular stage of lung development (20 days GA) and remained high in adult lungs. The combined administration of thyroid-releasing hormone and dexamethasone to pregnant rats between 16 and 18 days GA induced the expression of lung alpha rENaC in their fetuses. We conclude that alpha rENaC is expressed in mature fetal and adult alveolar epithelium and that it is influenced by hormones known to alter maturation of the fetal lung.

Glucocorticoids upregulate tropoelastin expression during late stages of fetal lung development

1995 ◽  
Vol 268 (3) ◽  
pp. L491-L500 ◽  
Author(s):  
R. A. Pierce ◽  
W. I. Mariencheck ◽  
S. Sandefur ◽  
E. C. Crouch ◽  
W. C. Parks
Keyword(s):  
Lung Development ◽  
Matrix Protein ◽  
Fetal Lung ◽  
Extracellular Matrix Protein ◽  
Transferase Activity ◽  
Mrna Levels ◽  
Pregnant Rats ◽  
Fetal Lung Development ◽  
Chloramphenicol Acetyl Transferase Activity

The production of elastin, an essential extracellular matrix protein of terminal airway interstitium, occurs mostly during early development. Because glucocorticoids influence airway maturation, we studied the effect of dexamethasone (Dex) on tropoelastin expression during fetal lung development. Timed-pregnant rats were treated with Dex (1 mg/kg daily), and fetal lungs were collected 3 days later at 17, 19, and 21 days of gestation. Dex treatment resulted in about a threefold increase in tropoelastin mRNA levels at 19 days concomitant with accelerated airway development. By in situ hybridization, Dex treatment increased the number of tropoelastin-expressing cells and the level of tropoelastin mRNA per cell. In organ culture, Dex increased lung tropoelastin expression and augmented cortisol stimulation of tropoelastin expression. In fetal pulmonary artery smooth muscle cells, 10(-8) M Dex upregulated tropoelastin mRNA expression and increased tropoelastin promoter-chloramphenicol acetyl transferase activity in transient transfections. These data indicate that pharmacologically administered glucocorticoids transcriptionally upregulate fetal lung tropoelastin expression and suggest that steroid hormones may be important regulators of elastin production in vivo.

scholarly journals Feedback Inhibition of the epithelial Na+ channel (ENaC): in vitro vs. in vivo

2012 ◽  
Vol 26 (S1) ◽  
Author(s):  
Ankit Bharat Patel ◽  
Gustavo Frindt ◽  
Su Deng ◽  
Lawrence G. Palmer
Keyword(s):  
Feedback Inhibition ◽  
Na Channel ◽  
Epithelial Na Channel

Cellular distribution of insulin-like growth factor binding protein mRNAs and peptides during rat lung development

1997 ◽  
Vol 155 (2) ◽  
pp. 313-327 ◽  
Author(s):  
LD Wallen ◽  
W Myint ◽  
K Nygard ◽  
S Shimasaki ◽  
DR Clemmons ◽  
...  
Keyword(s):  
Airway Epithelium ◽  
Lung Development ◽  
Fetal Lung ◽  
Northern Analysis ◽  
Postnatal Life ◽  
Mrna Levels ◽  
Igf Binding Proteins ◽  
Paracrine Factors ◽  
Igfbp 3

A role for IGF binding proteins (IGFBPs) in lung development is suggested by the identification of IGFBPs in lung tissue and production of IGFBPs by fetal lung cells in culture. To characterize the expression of IGFBPs during lung development in the rat in vivo (16 days gestation through adulthood), the expression of IGFBP mRNAs (IGFBP-1 to IGFBP-6) was examined by Northern analysis and in situ hybridization, and IGFBP peptides (IGFBP-2, IGFBP-3, and IGFBP-5) were localized by immunohistochemistry. IGFBP-1 mRNA was not detectable. IGFBP-2 mRNA (1.8 kb) was expressed in both fetal and postnatal life with peak expression during the fetal pseudoglandular stage. IGFBP-2 mRNA was localized mainly to airway epithelium. IGFBP-3 mRNA (2.4 kb) was maximally expressed postnatally in the saccular stage of lung development; it was identified in airway epithelium and interstitium in the fetal lung, but predominantly in airway epithelium after birth. IGFBP-4 (2.6 kb) and IGFBP-5 (6.0 kb) mRNA levels were maximal after birth, from 3 to 21 days postnatal (saccular and alveolar stage). IGFBP-4 mRNA was localized primarily to the interstitium and blood vessels early in development, but was abundant in airway epithelium in the adult. IGFBP-5 mRNA was most abundant in the airway epithelium. IGFBP-3, IGFBP-4, IGFBP-5, and to a lesser extent IGFBP-6 were localized to the large cartilaginous airways in the adult. IGFBP-2, IGFBP-3, and IGFBP-5 peptides were distributed more widely than their respective mRNAs, with a temporal pattern of immunoreactivity following that of their mRNAs. Maximal staining was noted in airway epithelium for IGFBP-2 in the newborn, for IGFBP-3 in the saccular stage (newborn to 3 days postnatal), and for IGFBP-5 in the alveolar stage (5 to 21 days postnatal). Our studies demonstrate that IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-5 are synthesized and distributed in spatially and temporally different patterns in the developing lung. The widespread distribution of IGFBP immunoreactivity compared with their respective mRNAs suggests that IGFBPs are important paracrine factors in the regulation of IGF action in the developing lung.

scholarly journals Regional distribution, developmental changes, and cellular localization of CNTF-mRNA and protein in the rat brain.

1991 ◽  
Vol 115 (2) ◽  
pp. 447-459 ◽  
Author(s):  
K A Stöckli ◽  
L E Lillien ◽  
M Näher-Noé ◽  
G Breitfeld ◽  
R A Hughes ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Olfactory Bulb ◽  
Cellular Localization ◽  
Time Course ◽  
Regional Distribution ◽  
Developmental Expression ◽  
Adult Rats

Ciliary neurotrophic factor (CNTF) is a potent survival molecule for a variety of embryonic neurons in culture. The developmental expression of CNTF occurs clearly after the time period of the physiological cell death of CNTF-responsive neurons. This, together with the sites of expression, excludes CNTF as a target-derived neuronal survival factor, at least in rodents. However, CNTF also participates in the induction of type 2 astrocyte differentiation in vitro. Here we demonstrate that the time course of the expression of CNTF-mRNA and protein in the rat optic nerve (as evaluated by quantitative Northern blot analysis and biological activity, respectively) is compatible with such a glial differentiation function of CNTF in vivo. We also show that the type 2 astrocyte-inducing activity previously demonstrated in optic nerve extract can be precipitated by an antiserum against CNTF. Immunohistochemical analysis of astrocytes in vitro and in vivo demonstrates that the expression of CNTF is confined to a subpopulation of type 1 astrocytes. The olfactory bulb of adult rats has comparably high levels of CNTF to the optic nerve, and here again, CNTF-immunoreactivity is localized in a subpopulation of astrocytes. However, the postnatal expression of CNTF in the olfactory bulb occurs later than in the optic nerve. In other brain regions both CNTF-mRNA and protein levels are much lower.

scholarly journals Heat shock and developmental regulation of the Drosophila melanogaster hsp83 gene.

1989 ◽  
Vol 9 (4) ◽  
pp. 1746-1753 ◽  
Author(s):  
H Xiao ◽  
J T Lis
Keyword(s):  
Drosophila Melanogaster ◽  
Heat Shock ◽  
Fusion Gene ◽  
Developmental Expression ◽  
Regulatory Sequence ◽  
Mrna Levels ◽  
Hsp70 Gene ◽  
High Level ◽  
Hsp83 Gene

In contrast to the hsp70 gene, whose expression is normally at a very low level and increases by more than 2 orders of magnitude during heat shock, the hsp83 gene in Drosophila melanogaster is expressed at high levels during normal development and increases only severalfold in response to heat shock. Developmental expression of the hsp83 gene consists of a high level of tissue-general, basal expression and a very high level of expression in ovaries. We identified regions upstream of the hsp83 gene that were required for its developmental and heat shock-induced expression by assaying beta-galactosidase activity and mRNA levels in transgenic animals containing a series of 5' deletion and insertion mutations of an hsp83-lacZ fusion gene. Deletion of sequences upstream of the overlapping array of a previously defined heat shock consensus (HSC) sequence eliminated both forms of developmental expression of the hsp83 gene. As a result, the hsp83 gene with this deletion mutation was regulated like that of the hsp70 gene. Moreover, an in vivo polymer competition assay revealed that the overlapping HSC sequences of the hsp83 gene and the nonoverlapping HSC sequences of the hsp70 gene had similar affinities for the factor required for heat induction of the two heat shock genes. We discuss the functional similarity of hsp70 and hsp83 heat shock regulation in terms of a revised view of the heat shock-regulatory sequence.

Effects of the JNK inhibitor anthra[1,9-cd]pyrazol-6(2H)-one (SP-600125) on soluble guanylyl cyclase α1gene regulation and cGMP synthesis

2005 ◽  
Vol 289 (4) ◽  
pp. C778-C784 ◽  
Author(s):  
Joshua S. Krumenacker ◽  
Alexander Kots ◽  
Ferid Murad
Keyword(s):  
Pc12 Cells ◽  
Guanylyl Cyclase ◽  
Soluble Guanylyl Cyclase ◽  
Fetal Lung ◽  
Cell Types ◽  
Mrna Levels ◽  
Disease States ◽  
Jun Kinase ◽  
Constitutively Active

The decreased expression of the nitric oxide (NO) receptor, soluble guanylyl cyclase (sGC), occurs in response to multiple stimuli in vivo and in cell culture and correlates with various disease states such as hypertension, inflammation, and neurodegenerative disorders. The ability to understand and modulate sGC expression and cGMP levels in any of these conditions could be a valuable therapeutic tool. We demonstrate herein that the c-Jun NH2-terminal kinase JNK II inhibitor anthra[1,9- cd]pyrazol-6(2 H)-one (SP-600125) completely blocked the decreased expression of sGCα1-subunit mRNA by nerve growth factor (NGF) in PC12 cells. Inhibitors of the ERK and p38 MAPK pathways, PD-98059 and SB-203580, had no effect. SP-600125 also inhibited the NGF-mediated decrease in the expression of sGCα1protein as well as sGC activity in PC12 cells. Other experiments revealed that decreased sGCα1mRNA expression through a cAMP-mediated pathway, using forskolin, was not blocked by SP-600125. We also demonstrate that TNF-α/IL-1β stimulation of rat fetal lung (RFL-6) fibroblast cells resulted in sGCα1mRNA inhibition, which was blocked by SP-600125. Expression of a constitutively active JNKK2-JNK1 fusion protein in RFL-6 cells caused endogenous sGCα1mRNA levels to decrease, while a constitutively active ERK2 protein had no effect. Collectively, these data demonstrate that SP-600125 may influence the intracellular levels of the sGCα1-subunit in certain cell types and may implicate a role for c-Jun kinase in the regulation of sGCα1expression.

scholarly journals Ethanol Modulates the VR-1 Variant Amiloride-insensitive Salt Taste Receptor. I. Effect on TRC Volume and Na+ Flux

2005 ◽  
Vol 125 (6) ◽  
pp. 569-585 ◽  
Author(s):  
Vijay Lyall ◽  
Gerard L. Heck ◽  
Tam-Hao T. Phan ◽  
Shobha Mummalaneni ◽  
Shahbaz A. Malik ◽  
...  
Keyword(s):  
Taste Receptor ◽  
Na Channel ◽  
Mineral Salts ◽  
Tonic Component ◽  
Salt Taste ◽  
Vanilloid Receptor 1 ◽  
Intracellular Na Activity ◽  
Nerve Recordings ◽  
Epithelial Na Channel

The effect of ethanol on the amiloride- and benzamil (Bz)-insensitive salt taste receptor was investigated by the measurement of intracellular Na+ activity ([Na+]i) in polarized rat fungiform taste receptor cells (TRCs) using fluorescence imaging and by chorda tympani (CT) taste nerve recordings. CT responses were monitored during lingual stimulation with ethanol solutions containing NaCl or KCl. CT responses were recorded in the presence of Bz (a specific blocker of the epithelial Na+ channel [ENaC]) or the vanilloid receptor-1 (VR-1) antagonists capsazepine or SB-366791, which also block the Bz-insensitive salt taste receptor, a VR-1 variant. CT responses were recorded at 23°C or 42°C (a temperature at which the VR-1 variant salt taste receptor activity is maximally enhanced). In the absence of permeable cations, ethanol induced a transient decrease in TRC volume, and stimulating the tongue with ethanol solutions without added salt elicited only transient phasic CT responses that were insensitive to elevated temperature or SB-366791. Preshrinking TRCs in vivo with hypertonic mannitol (0.5 M) attenuated the magnitude of the phasic CT response, indicating that in the absence of mineral salts, transient phasic CT responses are related to the ethanol-induced osmotic shrinkage of TRCs. In the presence of mineral salts, ethanol increased the Bz-insensitive apical cation flux in TRCs without a change in cell volume, increased transepithelial electrical resistance across the tongue, and elicited CT responses that were similar to salt responses, consisting of both a transient phasic component and a sustained tonic component. Ethanol increased the Bz-insensitive NaCl CT response. This effect was further enhanced by elevating the temperature from 23°C to 42°C, and was blocked by SB-366791. We conclude that in the presence of mineral salts, ethanol modulates the Bz-insensitive VR-1 variant salt taste receptor.

Fetal lung epithelial cells contain two populations of amiloride-sensitive Na+ channels

1993 ◽  
Vol 264 (4) ◽  
pp. L357-L364 ◽  
Author(s):  
S. Matalon ◽  
M. L. Bauer ◽  
D. J. Benos ◽  
T. R. Kleyman ◽  
C. Lin ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Fetal Lung ◽  
Lung Epithelial Cells ◽  
Na Channel ◽  
Na Transport ◽  
Plasma Membrane Vesicles ◽  
Binding Studies ◽  
Channel Protein ◽  
Lung Epithelial

Active Na+ transport by the alveolar epithelium plays a major role in reabsorption of the fetal lung fluid after birth. We characterized the biochemical and physiological characteristics of Na+ conductive pathways in distal fetal lung epithelial (FLE) cells isolated from 20-day-old rat fetuses. We demonstrated that a polyclonal antibody to Na+ channel protein (NaAb) binds to the plasma membranes of FLE cells. In Western blot studies, this NaAb and an anti-idiotypic monoclonal antibody to the amiloride-binding subunit of the Na+ channel protein recognized 150- and 90-kDa polypeptides in plasma membrane vesicles of FLE. 22Na+ flux measurements across plasma membrane vesicles of FLE revealed the existence of electrogenic Na+ transport, which was twice as high as the corresponding adult value. One hundred micromolars of amiloride, benzamil, and 5-(N-ethyl-N-isopropyl)-2'-4'-amiloride inhibited 30, 40, and 70% of the electrogenic Na+ transport across plasma membrane vesicles of FLE cells, respectively. The half-maximum inhibition of electrogenic Na+ transport by these substances occurred between 0.3 and 1 microM. [3H]benzamil equilibrium binding studies in membrane vesicles of FLE cells revealed the existence of two binding sites that had dissociation constant values of 19 and 1,525 nM, respectively. These data indicate the presence of both high- and low-amiloride affinity Na+ conductive pathways (channels) in FLE cells.

Recovery of rat type II cell surfactant components during primary cell culture

2002 ◽  
Vol 282 (2) ◽  
pp. L267-L276 ◽  
Author(s):  
Sandra R. Bates ◽  
Linda W. Gonzales ◽  
Jian-Qin Tao ◽  
Peter Rueckert ◽  
Philip L. Ballard ◽  
...  
Keyword(s):  
Cell Culture ◽  
Protein Content ◽  
Culture System ◽  
Fetal Lung ◽  
Hormone Treatment ◽  
Type Ii Cells ◽  
Mrna Levels ◽  
Type Ii ◽  
Adult Rats ◽  
Adult Type

A culture system designed to maintain the differentiated characteristics of rat type II cells based on protocols used for human fetal lung pneumocytes was investigated. Type II cells were isolated either from adult rats with elastase (adult type II cells) or from young rats (4–11 days postnatal) with collagenase and trypsin (young type II cells) and were incubated with dexamethasone (Dex, 10 nM) and cAMP (0.1 mM). By day 4 of culture with hormone treatment, the mRNA levels in adult type II cells were less than 3% of day 0 values, whereas surfactant protein (SP)-A protein content was 26%. However, young type II cells maintained lamellar bodies and microvilli and secreted phospholipid in response to ATP. SP-A, -B, and -C mRNA levels were elevated to 159, 350, and 39%, respectively, of day 0 values with a synergistic response to Dex and cAMP, whereas SP-A protein content rose to 119%. Surfactant mRNA and protein did not recover in cells cultured without hormones. This cell culture system restored surfactant components in rat type II cells.

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