Protein-tyrosine Phosphatase Reduces the Number of Apical Small Conductance K+ Channels in the Rat Cortical Collecting Duct

Wei, Yuan; Bloom, Peter; Gu, Ruimin; Wang, Wenhui

doi:10.1074/jbc.m000783200

Cited by 43 publications

(49 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Furthermore, we have shown that ROMK1 was a substrate of PTK and that tyrosine phosphorylation of ROMK increased during K depletion and decreased by high K intake (15). The role of PTK in regulating ROMK channel activity in the CCD is further established by the observation that inhibition of PTK increases (1), whereas inhibition of protein tyrosine phosphatase decreases (20), ROMK channel activity. The inhibitory effect of PTK on ROMK1 is the result of stimulation of the ROMK internalization.…”

Section: Fig 10mentioning

confidence: 79%

Superoxide Anions Are Involved in Mediating the Effect of Low K Intake on c-Src Expression and Renal K Secretion in the Cortical Collecting Duct

Babilonia

Wei

Sterling

et al. 2005

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

It is well known that K restriction suppresses renal K excretion (2). This is achieved, at least in part, by decreasing the apical K conductance in the cortical collecting duct (CCD) 1 and by stimulating K absorption in the outer medullary collecting duct (3, 4). However, the mechanism by which low K intake suppresses the apical K channels is not completely understood. We previously demonstrated that low K intake increased the expression of Src family protein tyrosine kinase (PTK) such as c-Src and c-Yes (1) and that inhibition of PTK increased the apical ROMK-like small conductance (SK) channels (1). This suggests that PTK is involved in mediating the effect of low K intake on the apical K channels and that increases in PTK activity and expression are important for suppression of renal K secretion during K depletion.Low K intake has been reported to increase the production of O 2. anion in rabbit carotid arteries (5). Moreover, it has beenshown that H 2 O 2 stimulates the phosphorylation of c-Jun in endothelial cells, an indication of activation of transcription factor (6). Therefore, it is possible that increases in O 2 . or related products induced by low K intake may be an upstream signal responsible for mediating the effect of low K intake on PTK expression and K secretion in the kidney. This hypothesis was tested in the present study by examining whether O 2 . and related products such as H 2 O 2 can mimic the effect of low K intake and stimulate the expression of PTK in the CCD. We also examined whether decreases in O 2 . and related products with tempol could attenuate the effect of low K intake on c-Src expression, ROMK channel activity, and renal K excretion. EXPERIMENTAL PROCEDURESAnimals-Sprague-Dawley rats (6 -8 weeks, either sex) were purchased from Taconic Farms (Germantown, NY). Rats were housed in metabolic cages for 7 days to study urinary K excretion. After 3 days of training in the cage, rats were divided into three groups: 1) control group in which animals were kept on a normal K (1.1%) diet and had a daily intraperitoneal injection of saline for 1 week; 2) the low K group in which rats were maintained on a K-deficient (KD) diet and received a daily intraperitoneal injection of saline for 7 days; and 3) the tempol-treated group in which rats were also fed with KD diet and had a daily intraperitoneal injection of tempol (15 mg/kg) for 1 week. Data regarding the 24-h food intake, body weight, and urine output were recorded. Urinary Na and K concentrations were measured by a flame photometer, and daily Na and K excretion were calculated as mEq/24 h. Animals were anesthetized with pentobarbital (60 mg/kg), and blood samples were drawn from the heart to measure the plasma K and Na concentrations. Rats were then killed, and the abdomens were opened to remove the kidneys.Tissue Preparation-The renal cortex and the outer medulla were separated under a dissecting microscope and suspended in radioimmune precipitation assay buffer solution (1:8 ratio, w/v) containing 1ϫ phosphate-buffered saline, 1% No...

show abstract

Section: Fig 10mentioning

confidence: 79%

Superoxide Anions Are Involved in Mediating the Effect of Low K Intake on c-Src Expression and Renal K Secretion in the Cortical Collecting Duct

Babilonia

Wei

Sterling

et al. 2005

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…Purified human CG (hCG CR-127, potency 14 900 IU/mg) was a gift from Dr Parlow, National Hormone and Pituitary Program, NIDDK, NIH (Bethesda, MD, USA). Stimulations were performed in the presence or absence of phenylarsine oxide (PAO), a cell-permeable PTP inhibitor (García Morales et al 1990, Wei et al 2000, added to the cells 10 min before the stimuli. Following the appropriate treatments, MA-10 cells were placed in an incubator at 36 C and 5% CO 2 for the time periods indicated in the Figure legends.…”

Section: Conditions For Incubation Of Ma-10 Cells With Ptp Inhibitorsmentioning

confidence: 99%

Protein tyrosine phosphatases are involved in LH/chorionic gonadotropin and 8Br-cAMP regulation of steroidogenesis and StAR protein levels in MA-10 Leydig cells

Paz

Maciel²,

Maloberti³

et al. 2002

Journal of Endocrinology

View full text Add to dashboard Cite

The LH signal transduction pathway features the activation of protein tyrosine phosphatases (PTPs) as one of the components of a cascade that includes other well characterized events such as cAMP-dependent protein kinase A (PKA) activation. Moreover, the action of PTPs is required to increase the rate-limiting step in steroid biosynthesis, namely the cAMP-regulated transfer of cholesterol to the inner mitochondrial membrane. Since both PKA activity and steroidogenic acute regulatory (StAR) protein induction are obligatory steps in this transfer of cholesterol, the present study was performed to investigate the role of PTPs in the regulation of PKA activity and StAR expression in response to LH/chorionic gonadotropin (CG) and 8Br-cAMP in MA-10 cells. While the exposure of MA-10 cells to the PTP inhibitor, phenylarsine oxide (PAO), did not modify PKA activity, it partially inhibited the effect of human CG and cAMP analog on StAR protein levels. Time-course studies demonstrated that PAO inhibited cAMP induction of StAR protein and mRNA. At 30 min, the effect on cAMPstimulated StAR protein levels was a 35% inhibition, progressing to up to 90% inhibition at 120 min of stimulation. The maximal inhibitory effect on cAMP-induced StAR mRNA level was obtained at 60 min (85%). In summary, these results demonstrate that inhibition of PTP activity affected both StAR protein and mRNA synthesis and suggest that the activity of hormone-regulated PTPs is a requirement in the LH signaling cascade that results in the up-regulation of StAR protein and, subsequently, increased steroid synthesis.

show abstract

“…We previously demonstrated that low K intake decreases the apical small-conductance K (SK) channel activity (6). The effect of low K intake on the SK channels is mediated by a protein tyrosine kinase (PTK)-dependent pathway (7,8) because inhibition of PTK increases the SK channel activity in the CCD (9,10). Moreover, we have shown that low K intake increases superoxide levels which mediate the effect of low K intake on PTK expression (6) and that suppression of superoxide production with tempol diminishes the effect of low K intake on c-Src expression (6).…”

mentioning

confidence: 99%

Mitogen-Activated Protein Kinases Inhibit the ROMK (Kir 1.1)-Like Small Conductance K Channels in the Cortical Collecting Duct

Babilonia

Wang

et al. 2006

Journal of the American Society of Nephrology

View full text Add to dashboard Cite

It was demonstrated previously that low dietary potassium (K) intake stimulates Src family protein tyrosine kinase (PTK) expression via a superoxide-dependent signaling. This study explored the role of mitogen-activated protein kinase (MAPK) in mediating the effect of superoxide anions on PTK expression and ROMK (Kir 1.1) channel activity. Western blot analysis demonstrated that low K intake significantly increased the phosphorylation of P38 MAPK (P38) and extracellular signalregulated kinase (ERK) but had no effect on phosphorylation of c-JUN N-terminus kinase in renal cortex and outer medulla.

show abstract

Protein-tyrosine Phosphatase Reduces the Number of Apical Small Conductance K+ Channels in the Rat Cortical Collecting Duct

Cited by 43 publications

References 35 publications

Superoxide Anions Are Involved in Mediating the Effect of Low K Intake on c-Src Expression and Renal K Secretion in the Cortical Collecting Duct

Superoxide Anions Are Involved in Mediating the Effect of Low K Intake on c-Src Expression and Renal K Secretion in the Cortical Collecting Duct

Protein tyrosine phosphatases are involved in LH/chorionic gonadotropin and 8Br-cAMP regulation of steroidogenesis and StAR protein levels in MA-10 Leydig cells

Mitogen-Activated Protein Kinases Inhibit the ROMK (Kir 1.1)-Like Small Conductance K Channels in the Cortical Collecting Duct

Contact Info

Product

Resources

About