Signaling and distribution of NPR-Bi, the human splice form of the natriuretic peptide receptor type B
Jochen R. Hirsch,
Nikola Skutta, and
Eberhard Schlatter
Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, D-48149
Münster, Germany
Submitted 6 February 2003
; accepted in final form 21 April 2003
 |
ABSTRACT
|
---|
Recently, we described a splice variant of the human natriuretic peptide
receptor type B (NPR-Bi) in human proximal tubule cells [immortalized human
kidney epithelial cells (IHKE-1) that lacks a functional guanylate cyclase
domain (Hirsch JR, Meyer M, Mägert HJ, Forssmann WG, Mollerup S, Herter
P, Weber G, Cermak R, Ankorina-Stark I, Schlatter E, and Kruhøffer M.
J Am Soc Nephrol 10: 472480, 1999). Its signaling pathway does
not include cGMP, cAMP, or Ca2+ but leads to inhibition
of K+ channels. In patch-clamp experiments, effects of tyrosine
kinase receptor blockers on C-type natriuretic peptide (CNP)-mediated
depolarizations of membrane voltages (Vm) of IHKE-1 cells
were tested. The epidermal growth factor (EGF) receptor blocker genistein (10
µM) abolished the effect of CNP (0.2 ± 0.4 mV, n = 7), and
comparable results were obtained with 10 µM daidzein (n = 8).
Aminogenistein (10 µM, n = 5) and tyrphostin AG1295 (10 µM,
n = 5) had no significant effects. EGF (1 nM) hyperpolarized cells by
5.3 ± 0.8 mV (n = 5). This effect was completely
blocked by genistein or daidzein. The Cl channel blocker
NPPB (10 µM, n = 5) inhibited the EGF-mediated hyperpolarization.
mRNA expression of NPR-B and NPR-Bi shows reversed patterns along the human
nephron. NPR-B is highly expressed in glomeruli and proximal tubules, whereas
NPR-Bi shows strong signals in the distal nephron. Expression of NPR-Bi in the
cortical collecting duct was also confirmed with immunohistochemistry. In
other human tissues, NPR-Bi shows strongest expression in pancreas and lung,
whereas in the heart and liver NPR-B is the dominating receptor. In
conclusion, CNP inhibits an apical K+ channel in IHKE-1 cells
independently of cGMP and so far this effect can only be blocked by genistein
and daidzein. Tyrosine phosphorylation might be the missing link in the
signaling pathway of CNP/NPR-Bi.
C-type natriuretic peptide; signal transduction; tyrosine kinase; patch clamp analysis; proximal tubule; kidney
NATRIURETIC PEPTIDES ARE structurally related peptides that bind
to different receptors and display a variety of biological actions
(6,
16). Although quite a lot is
known about the actions of ANP and the related urodilatin that binds, similar
to BNP, to the natriuretic peptide receptor (NPR)-A (GC-A), little is known
about C-type natriuretic peptide (CNP)
(1,
11,
12). CNP, which is found in
the plasma and urine as a 53- and 22-amino acid ring-forming peptide, binds to
the NPR-B (GC-B) receptor, which leads to an increase in intracellular cGMP
(4). Recently, a splice variant
of the NPR-B receptor was detected and described as NPR-Bi. This receptor
carries a 71-bp insert on the mRNA level, leading to a frameshift and
truncated protein when translated
(8). Due to the generation of
an early stop codon, the receptor lacks a functional guanylate cyclase domain
and does not increase intracellular cGMP when activated by CNP
(8). cGMP-independent signaling
for natriuretic peptides has so far only been described for the NPR-C or
"clearance" receptor that can influence the adenylate cyclase
activity through G proteins (3,
13). We speculated that
tyrosine phosphorylation might be the signaling pathway for the NPR-Bi
receptor (7,
8).
It is known that phosphorylation processes regulate the activity of
guanylate cyclase receptors
(15). Recently, it could be
shown for the guanylate cyclase receptor GC-C, which is bound by guanylin and
uroguanylin, that not only serine/threonine-specific phosphorylation steps
regulate guanylate cyclase receptors but also tyrosine phosphorylation
(5).
In this study, we demonstrate that CNP inhibits K+ conductance
independently of cGMP and that this effect can be blocked only by genistein
and daidzein but not by the structurally related aminogenistein or another
tyrosin kinase receptor blocker tyrphostin AG1295. Furthermore, we show the
expression pattern of NPR-Bi in human tissues, especially in various segments
of the human kidney.
 |
MATERIALS AND METHODS
|
---|
Cell culture. Immortalized human kidney epithelial (IHKE-1) cells
(derived from human embryonic kidneys) were cultured as described previously
(18). In short, IHKE-1 cells
(passages 162-188) were grown in 50-ml tissue culture flasks
(Greiner, Frickenhausen, Germany) in Dulbecco's modified Eagle's/F-12 medium
(1:1) containing 15 mM HEPES, pH 7.3, 1.6 nM EGF, 100 nM hydrocortisone, 83
µM transferrin/insulin, 29 nM Na2SeO3, 10 mM
NaHCO3, 20 mM L-glutamine, 1,000 U/l
penicillin/streptomycin, and 1% fetal calf serum. Cells were incubated at
37°C in an atmosphere of 5% CO2-95% air. After 7 days, the
confluent monolayers were trypsinized with Ca2+- and
Mg2+-free phosphate-buffered saline and 0.05%
trypsin-EDTA (Biochrom, Berlin, Germany). Cells grew polarized on glass
coverslips, with the apical surface facing upward.
Patch-clamp studies. Coverslips with confluent IHKE-1 monolayers
were mounted at the bottom of a perfusion chamber on an inverted microscope
(Axiovert 10, Zeiss, Oberkochen, Germany). The perfusion chamber was
continuously perfused at a rate of 1020 ml/min at 37°C with a
standard solution containing (in mM) 145 NaCl, 1.6
K2HPO4, 0.4 KH2PO4, 5
D-glucose, 1 MgCl2, and 1.3
Ca2+-gluconate, pH 7.4. Cells were rinsed for at least
20 min before the electrophysiological measurements.
Membrane voltages (Vm) were measured with the slow
whole cell patch-clamp technique. For this method, pipettes were filled with a
solution containing (in mM) 95 K+-gluconate, 30 KCl, 4.8
Na2HPO4, 1.2 NaH2PO4,5
D-glucose, 0.73 Ca2+-gluconate, 1 EGTA, 1.03
MgCl2, and 1 ATP, pH 7.2. To this solution 162 µM nystatin was
added before use. Patch pipettes had an input resistance of 2.512.5
M
. Vm was measured in the current clamp mode of a
patch-clamp amplifier (U. Fröbe, Physiologisches Institut,
Universität Freiburg, Germany) and recorded continuously on a pen
recorder (WeKaGraph WK-250R, WKK, Kaltbrunn, Switzerland).
RT-PCR analysis. Total RNA was isolated using the RNeasy-kit
(Qiagen, Hilden, Germany). Isolated total RNA was incubated with 10 U DNase I
(Promega, Heidelberg, Germany) at 37°C for 1 h to digest isolated traces
of genomic DNA. RNA and DNase I were then separated by an additional cleanup
step using a new RNeasy column. cDNA first-strand synthesis was performed in a
total reaction volume of 30 µl containing 5 µg total RNA, 10 nM dNTP-Mix
(Biometra, Göttingen, Germany), 1 nM p(dT)10 nucleotide primer
(Boehringer, Mannheim, Germany), and 200 U molony murine leukemia virus
reverse transcriptase (Promega). Of each cDNA first-strand reaction mixture,
was then subjected to a
50-µl PCR reaction in a UNO II thermo cycler (Biometra) using 20 pmol of
each primer and 1 U of Taq DNA polymerase (Qiagen). Reaction
conditions were as follows: 3 min at 94°C, 30 s at 59°C, and 1 min at
72°C, 1 cycle; 30 s at 94°C, 30 s at at the optimal annealing
temperature (OAT), and 1 min at 72°C, 30 cycles; and 30 s at 94°C, 30
s at OAT, and 10 min at 72°C, 1 cycle. PCR reaction products were analyzed
by agarose gel electrophoresis. Positive signals obtained from PCR experiments
were sequenced by SeqLab (Göttingen, Germany). The following PCR primers
were used (listed in 5'- to 3'-direction). The sequence is
followed by the expected fragment length for the respective sense and
antisense primer: NPR-Bi sense: GAC TCT CAC TCC AGC CCT AGT CTC, NPR-Bi
antisense: TTC AGC GCT TGA CCA TTA GAC TCC, fragment length: 169 bp, OAT =
60°C; NPR-B sense: GAG ACG ATT GGG GAT GCT TA, NPR-B antisense: TTC AGC
GCT TGA CCA TTA GAC TCC; fragment length: 277 bp, OAT = 60°C; GAPDH sense:
CTG CCC CCT CTG CTG ATG, GAPDH antisense: GTC CAC CAC CCT GTT GCT GT, fragment
length: 614 bp, OAT = 61°C.
Immunocytochemistry. Kryo slices of a human kidney were blocked
for 15 min at room temperature with 1% blocking agent (Roche, Mannheim,
Germany). The primary polyclonal antibody against NPR-Bi (Immundiagnostik,
Bensheim, Germany) was incubated overnight at 4°C in a wet chamber. After
three washing steps in PBS, the secondary antibody (goat-anti-rabbit, Vector,
Burlingame, CA) was incubated for 45 min followed by three more washing steps
in PBS. The kryo slices were then incubated for 45 min in streptavidin, Alexa
Fluor 594 Conjugate (Mobitec, Göttingen, Germany) followed by five
washing steps in PBS. Finally, the slices were covered with mounting media
containing DAPI (Vector).
Biochemicals. Human CNP was kindly provided by Dr. Knut Adermann
(IPF Pharmaceuticals, Hannover, Germany). Genistein, daidzein, aminogenistein,
and tyrphostin AG1295 were supplied by Calbiochem (Bad Soden, Germany). All
other standard chemicals were supplied by Calbiochem, Sigma (Taufkirchen,
Germany) or Merck (Darmstadt, Germany).
Statistical analysis. Data are presented as means ± SE,
with the number of experiments given in brackets. For statistical analyses,
Student's paired and unpaired two-sided t-tests were used. For paired
comparisons, each effect was compared with its own averaged pre- and
postexperimental controls. A P value <0.05 was considered
significant and is indicated by an asterisk.
 |
RESULTS
|
---|
To verify if the cGMP-independent CNP-induced depolarization in the human
proximal tubulus cell line IHKE-1 is specifically blocked by genistein or
generally blocked by a variety of tyrosine kinase receptor blockers, we tested
the epidermal growth factor (EGF) receptor blocker genistein, its
"inactive" form daidzein, the structurally related aminogenistein
that is also an inhibitor of the p56lck tyrosine kinase, and the
PDGF receptor blocker tyrphostin AG1295. In 57 patch-clamp experiments, the
membrane voltage (Vm) of IHKE-1 cells was 42
± 1 mV. In seven paired experiments, CNP (10 nM) depolarized
Vm by 2.8 ± 0.4 mV. In the presence of genistein
(10 µM), the CNP-induced depolarization was abolished (0.2 ± 0.4
mV). After the washout of genistein, CNP depolarized Vm
again by 1.4 ± 0.4 mV (Fig.
1). As a negative control, we used daidzein, the inactive form of
genistein. To our surprise, daidzein (10 µM) reversed the CNP-induced
depolarization (n = 8). Aminogenistein (10 µM, n = 5) and
tyrphostin AG1295 (10 µM, n = 5) had no significant effect on the
CNP-induced depolarization (Fig.
1).

View larger version (22K):
[in this window]
[in a new window]
|
Fig. 1. Effects of genistein (n = 7), daidzein (n = 8),
aminogenistein (n = 5), and tyrphostin AG1295 (n = 5) on the
C-type natriuretic peptide (CNP)-mediated depolarization of membrane voltage
(Vm) of immortalized human kidney epithelial (IHKE-1)
cells. In paired experiments, CNP (10 nM) depolarized Vm
of IHKE-1 cells by 3 mV. This depolarization was inhibited by the
epidermal growth factor (EGF) receptor blocker genistein and its
"inactive" form, daidzein, but not by the structurally related
p56lck tyrosine kinase blocker aminogenistein or the PDGF receptor
blocker tyrphostin AG1295.*P < 0.05.
|
|
To verify the specificity of genistein and daidzein, both were tested on
their inhibitory effect of the EGF-mediated signaling pathway. In five paired
experiments, EGF (1 nM) hyperpolarized Vm by 5.3
± 0.8 mV (Fig. 2). In
the presence of genistein, this effect was fully inhibited to 1.2 ± 1.1
mV and after the washout of genistein also fully reversible (4.1
± 0.9 mV). Daidzein again mimicked the effect of genistein, clearly
showing that this substance is not inactive in the human proximal tubule cell
line IHKE-1 (Fig. 2). Although
the CNP-induced depolarization is due to the inhibition of a K+
channel
(79),
the EGF-induced hyperpolarization is due to the inhibition of a
Ca2+-dependent Cl channel since the
Cl channel blocker NPPB (10 µM) blocked the EGF effect on
Vm (Fig.
2). Other Cl channel blockers, such as DIDS and
SITS, and Na+ channel blockers, such as amiloride, had no
significant effect on the EGF-mediated hyperpolarization (data not shown). EGF
also did not interact with CNP as there was no significant effect of EGF on
the CNP-induced depolarization (2.6 ± 0.4 vs. 2.7 ± 0.6 mV,
n = 6). This demonstrates that EGF and CNP act through independent
pathways as shown in a simplified cell model in
Fig. 3.

View larger version (16K):
[in this window]
[in a new window]
|
Fig. 2. Effects of genistein (n = 5), daidzein (n = 5), and NPPB
(n = 5) on the EGF-mediated hyperpolarization of
Vm of IHKE-1 cells. In paired experiments, EGF (1 nM)
hyperpolarized Vm of IHKE-1 cells by 35 mV. This
hyperpolarization was inhibited by the EGF receptor blocker genistein and its
"inactive" form, daidzein, and the
Ca2+-dependent Cl channel blocker
NPPB. *P < 0.05.
|
|

View larger version (18K):
[in this window]
[in a new window]
|
Fig. 3. Simplified cell model of IHKE-1 cell. The basolateral membrane contains the
Na+-K+-ATPase that provides the driving force for the
Na+-driven transport systems of the luminal membrane. Furthermore,
a housekeeping K+ channel allows K+ recycling across the
basolateral membrane. The exit pathways for the substrates are left out. The
luminal membrane contains, besides the already mentioned
Na+-coupled transport systems, an hIK-like K+ channel
that is most likely responsible for the repolarization of these cells, thus
establishing the driving force for the Na+-coupled transport
systems. This Ba2+-inhibitable K+ channel is
inhibited by CNP cGMP independently through the NPR-Bi receptor. This
inhibition can be reversed by genistein. Genistein also blocks the
EGF-mediated inhibition of a Cl channel in the same
membrane. Because this Cl channel is not blocked by SITS or
DIDS but NPPB, it is most likely a Ca2+-dependent
intermediate-conductance outwardly rectifying Cl channel
(ICOR).
|
|
Because we were interested in the distribution of NPR-Bi and NPR-B in the
human kidney, we performed RT-PCR on isolated glomeruli and tubules to check
for their expression pattern along the nephron.
Figure 4 shows the interesting
result. Although NPR-B is mainly and strongly expressed in glomeruli and
proximal tubules, NPR-Bi is weakly expressed in proximal tubules, stronger in
thick ascending limbs, and predominantly expressed in collecting ducts.
Because the PCR was performed with the same mRNA/cDNA batches for NPR-B and
NPR-Bi and each sample had its own GAPDH control, the data can be seen
semi-quantitatively, meaning expression of NPR-B is increasing toward the
proximal part of the nephron, whereas that of NPR-Bi is increasing toward the
distal parts of the human nephron (Fig.
4). This result is also confirmed by immunocytochemistry, which
shows a clear signal of the antibody against NPR-Bi in the luminal membrane of
the collecting duct (Fig. 5).
Due to the interesting reversed distribution pattern of NPR-B and NPR-Bi in
the nephron, we performed RT-PCR with different human tissue samples to
monitor the distribution of the two human receptors in other tissues. Two
signals of NPR-Bi clearly stuck out compared with NPR-B. The expression in
lung and pancreas was dominated by NPR-Bi
(Fig. 6). NPR-B expression was
strongest in the heart and liver. Keeping in mind that lung, pancreas, and
colon are the three tissues mostly affected in cystic fibrosis, we also
performed PCR experiments with human colon tissues, confirming that both
receptors are equally well expressed (data not shown).

View larger version (38K):
[in this window]
[in a new window]
|
Fig. 4. mRNA expression patterns of natriuretic peptide receptor (NPR)-Bi and NPR-B
in the human nephron amplified by RT-PCR. The intensity of the NPR-Bi signal
increases toward the distal part of the human nephron, being strongest in the
collecting duct, whereas the intensity of the NPR-B signals showed the
opposite distribution, being strongest in the glomeruli. As a positive
control, GAPDH was amplified for each segment (displayed is only one sample
because the intensities of the GAPDH signal did not vary). As negative
controls, all tests were performed in parallel with either no cDNA or no
Taq-polymerase.
|
|

View larger version (76K):
[in this window]
[in a new window]
|
Fig. 5. Immunocytochemistry using a polyclonal antibody against NPR-Bi in human
kidney slices. A positive signal (red staining) could only be obtained in the
luminal membrane of cortical collecting duct cells, confirming the result
found by RT-PCR. In addition, cell nuclei are stained blue (DAPI).
|
|

View larger version (54K):
[in this window]
[in a new window]
|
Fig. 6. mRNA expression patterns of NPR-Bi and NPR-B in different human tissues
amplified by RT-PCR. Although both receptors are equally well expressed in the
heart, brain, placenta, and liver tissue, expression of NPR-Bi is clearly
dominant in the lung and pancreas.
|
|
 |
DISCUSSION
|
---|
CNP is known to bind the natriuretic peptide B (NPR-B/GC-B) receptor and
increase intracellular cGMP. It is known to display biological actions in the
cardiorenal system, bronchial tree and pulmonary vasculature, and the
endocrine, gastrointestinal, and neuronal systems
(4). Recently, it was shown
that CNP can also act independently of cGMP by inhibiting a
Ca2+-dependent, intermediate-conductance, hIK1-like
K+ channel in human IHKE-1 cells derived from the human renal
proximal tubule (8). Besides
the well-known NPR-B receptor, a splice variant (NPR-Bi) was found that is the
dominant pathway for CNP in these cells. The NPR-Bi receptor lacks a
functional guanylate cyclase domain, thus inhibiting the hIK1-like
K+ channel cGMP independently. Furthermore, we were able to show
that neither Ca2+ nor cAMP played any role in the
regulation of this K+ conductance
(8). Due to the structure of
the receptor and a recent report that demonstrated a key role for tyrosine
phosphorylation in the activity of the related GC-C receptor
(5), we tested various tyrosine
kinase blockers. From these inhibitors, only genistein, a known inhibitor of
the EGF receptor (2), and its
inactive form, daidzein, were able to block the CNP-induced depolarization of
membrane voltage. Neither the structurally related aminogenistein nor the PDGF
receptor blocker tyrphostin AG1295 had any significant effects. Although
genistein and daidzein also blocked the EGF-mediated hyperpolarization, they
displayed no direct effect on the hIK1-like K+ channel itself
(8). A direct interaction
independent of tyrosine phosphorylation had been reported for some
K+ channels, a Cl channel, and the
Na+-2Cl-K+ cotransporter
(14,
19,
20). In IHKE-1 cells, daidzein
was also not an inactive substance but acted like genistein. So far, these two
substances are the only blockers capable of inhibiting the CNP-mediated
signaling through NPR-Bi, which is most likely related to tyrosine
phosphorylation. The hIK1-like K+ channel apparently plays an
important role in these human proximal tubule cells because it can be blocked
by ANP, BNP, and urodilatin cGMP dependently through NPR-A/GC-A
(9), by CNP cGMP independently
through NPR-Bi (8), and by
guanylin, uroguanylin, and STa cGMP dependently through GC-C
(17). Furthermore, cGMP
inhibits this K+ channel directly from the extracellular as well as
the intracellular surface (10)
as displayed in Fig. 7. The
diverse expression pattern of NPR-B and NPR-Bi in the human nephron clearly
indicates different tasks for CNP through these receptors. The
cGMP-independent pathway seems to play an important role in the human
collecting duct, where NPR-B is not expressed at all and NPR-Bi showed its
strongest signal on the mRNA and protein level. When the mRNA expression
pattern of NPR-Bi in various human tissues is viewed, it is striking that
signals from lung and pancreas stick out. The fact that NPR-Bi and NPR-B are
also strongly expressed in the human colon indicates a role for NPR-Bi in
cystic fibrosis-related tissues. Regulation of hIK1 in the basolateral
membrane of lung or colon cells by tyrosine phosphorylation might be a key
element in the regulation of Cl secretion in these cells.
Further investigations are needed to clarify the role of NPR-Bi and its
interaction with hIK1 and CFTR in human cell types such as Calu-3 (lung), T84
(colon), and CF-PAC (pancreas).

View larger version (21K):
[in this window]
[in a new window]
|
Fig. 7. Simplified cell model of IHKE-1 cell demonstrating the different
cGMP-dependent and -independent pathways used by natriuretic peptides to block
the hIK-like K+ channel of the apical membrane. The basolateral
membrane contains the Na+-K+-ATPase that provides the
driving force for the Na+-driven transport systems of the apical
membrane. Furthermore, a housekeeping K+ channel in the basolateral
membrane provides the stoichiometry. The exit pathways for the substrates are
left out. The luminal membrane contains, besides the already mentioned
Na+-coupled transport systems, an hIK-like K+ channel
that is most likely responsible for the repolarization of these cells, thus
establishing the driving force for the Na+-coupled transport
systems. This K+ channel is blocked directly by cGMP generated by
ANP, BNP, or urodilatin through the NPR-A/GC-A receptor, by guanylin,
uroguanylin, or STa through the GC-C receptor. Extracellular cGMP also
inhibits this K+ channel. cGMP is released into the tubular lumen
either by glomerular cells or by a newly described pump in proximal tubule
cells. CNP blocks this K+ channel cGMP independently through NPR-Bi
most likely by tyrosine phosphorylation, which can be blocked by
genistein.
|
|
 |
DISCLOSURES
|
---|
This work was supported by the Deutsche Forschungsgemeinschaft (Schl
277/55 to 56 and 111).
 |
ACKNOWLEDGMENTS
|
---|
The authors gratefully acknowledge the expert technical assistance of M.
Eich, U. Kleffner, U. Siegel, and H. Stegemann.
 |
FOOTNOTES
|
---|
Address for reprint requests and other correspondence: E. Schlatter,
Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, Domagkstr.
3a, D-48149 Münster, Germany (E-mail:
eberhard.schlatter{at}uni-muenster.de).
The costs of publication of this article were defrayed in part by the
payment of page charges. The article must therefore be hereby marked
``advertisement'' in accordance with 18 U.S.C. Section 1734 solely to
indicate this fact.
 |
REFERENCES
|
---|
- Abdulla HM.
The natriuretic peptides: universal volume controllers. Med
Hypotheses 56:
451453, 2001.[ISI][Medline]
- Akiyama T,
Ishida J, Nakagawa S, Ogawara H, Watanabe S, Itoh N, Shibuya M, and Fukami
Y. Genistein, a specific inhibitor of tyrosine-specific protein kinases.
J Biol Chem 262:
55925595, 1987.[Abstract/Free Full Text]
- Anand-Srivastava M, Sehl PD, and Lowe DG. Cytoplasmic domain of
natriuretic peptide receptor-C inhibits adenylyl cyclase. Involvement of a
pertussis toxin-sensitive G protein. J Biol Chem
271: 1932419329,
1996.[Abstract/Free Full Text]
- Barr CS, Rhodes
P, and Struthers AD. C-type natriuretic peptide.
Peptides 17:
12431251, 1996.[ISI][Medline]
- Bhandari R,
Mathew R, Vijayachandra K, and Visweswariah SS. Tyrosine phosphorylation
of the human guanylyl cyclase C receptor. J Biosci
25: 339346,
2000.[ISI][Medline]
- Brenner BM,
Ballermann BJ, Gunning ME, and Zeidel ML. Diverse biological actions of
atrial natriuretic peptide. Physiol Rev
70: 665699,
1990.[Free Full Text]
- Hirsch JR.
Renal K+-transport regulated by cGMP. In: Recent
Research Developments in Physiology, edited by Pandalai SG.
Trivandrum, India: Research Signpost, 2003.
- Hirsch JR,
Meyer M, Mägert HJ, Forssmann WG, Mollerup S, Herter P, Weber G, Cermak
R, Ankorina-Stark I, Schlatter E, and Kruhøffer M. cGMP-dependent
and independent inhibition of a K+ conductance by natriuretic
peptides. Molecular and functional studies in human proximal tubule cells.
J Am Soc Nephrol 10:
472480, 1999.[Abstract/Free Full Text]
- Hirsch JR,
Weber G, Kleta I, and Schlatter E. A novel cGMP-regulated K+
channel in immortalised human kidney epithelial cells (IHKE-1). J
Physiol 519.3:
645655, 1999.[Abstract/Free Full Text]
- Hirsch JR,
Weber G, Kleta I, and Schlatter E. cGMP serves as an extracellular
regulator of a Ca2+-dependent K+ channel in
immortalized human proximal tubule cells. Cell Physiol
Biochem 11:
7782, 2000.[ISI][Medline]
- Levin ER,
Gardner DG, and Samson WK. Mechanisms of disease. Natriuretic peptides.
N Engl J Med 339:
321328, 1998.[Free Full Text]
- Meyer M and
Forssmann WG. Renal actions of atrial natriuretic peptide. In:
Contemporary Endocrinology: Natriuretic Peptides in Health and
Disease, edited by Samson WK and Levin ER. Totowa, NJ: Humana,
1997, p. 147170.
- Murthy KS, Teng
BQ, Zhou H, Jin JG, Grider JR, and Makhlouf GM.
Gi-1/Gi-2-dependent signaling by single-transmembrane
natriuretic peptide clearance receptor. Am J Physiol Gastrointest
Liver Physiol 278:
G974G980, 2000.[Abstract/Free Full Text]
- Niisato N, Ito
Y, and Marunaka Y. Activation of Cl channel and
Na+/K+/2Cl cotransporter in renal
epithelial A6 cells by flavonoids: genistein, daidzein, and apigenin.
Biochem Biophys Res Commun 254:
368371, 1999.[ISI][Medline]
- Potter LR and
Hunter T. Activation of protein kinase C stimulates the dephosphorylation
of natriuretic peptide receptor-B at a single serine residue. A possible
mechanism of heterologous desensitization. J Biol Chem
275: 3109931106,
2000.[Abstract/Free Full Text]
- Rosenzweig A and Seidman CE. Atrial natriuretic factor and related hormones.
Annu Rev Biochem 60:
229255, 1991.[ISI][Medline]
- Sindic A,
Basoglu C, Cerci A, Hirsch JR, Potthast R, Kuhn M, Ghanekar Y, Visweswariah
SS, and Schlatter E. Guanylin, uroguanylin and heat-stable enterotoxin
activate guanylate cyclase C and/or a Pertussis toxin-sensitive G protein in
human proximal tubule cells. J Biol Chem
277: 1775817764,
2002.[Abstract/Free Full Text]
- Tveito G,
Hansteen IL, Dalen H, and Haugen A. Immortalization of normal human kidney
epithelial cells by Nickel(II). Cancer Res
49: 18291835,
1989.[Abstract]
- Washizuka T,
Horie M, Obayashi K, and Sasayama S. Genistein inhibits slow component
delayed-rectifier K currents via a tyrosine kinase-independent pathway.
J Mol Cell Cardiol 30:
25772590, 1998.[ISI][Medline]
- Zhang ZH and
Wang Q. Modulation of a cloned human A-type voltage-gated potassium
channel (hKv1.4) by the protein tyrosine kinase inhibitor genistein.
Pflügers Arch 440:
784792, 2000.[ISI][Medline]
Copyright © 2003 by the American Physiological Society.