Abstract
The present study examined the effect of epidermal growth factor (EGF) on Na-Pi cotransport in a tubular epithelial cell line derived from the opossum kidney (OKP cells). EGF caused a time- and dose-dependent decrease in Na-Pi cotransport. The inhibition of Na-Pi cotransport by 10-8 M EGF was first demonstrable after 18 h with maximal effect seen at 24 h. EGF inhibited Na-Pi cotransport by decreasing the maximal velocity (10.8 ± 0.9 in control vs. 4.9 ± 0.8 nmol 32Pi·4 min-1·mg protein-1 in EGF, P < 0.001). Northern blot analysis indicated that EGF caused a significant decrease in NaPi-4 mRNA abundance. The abundance of NaPi-4 mRNA relative to β-actin and/or glyceraldehyde-3-phosphate dehydrogenase mRNA was decreased by twofold in OK cells treated with EGF for 4 h and threefold in OKP cells treated with EGF for 24 h. Thus the decrease in NaPi-4 mRNA abundance preceded the decrease in Na-Pi cotransport activity. Inhibition of transcription with actinomycin D and protein synthesis with cycloheximide prevented the inhibition of Na-Pi cotransport. Furthermore, inhibition of phospholipase C activity with U-73,122 also significantly blocked the inhibitory effect of EGF on Na-Pi cotransport. The results indicate that EGF-induced decrease in OKP Na-Pi cotransport is mediated through a decrease in NaPi-4 mRNA and activation of the phospholipase C signaling pathway.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Renal Fluid and Electrolyte Physiology |
| Volume | 268 |
| Issue number | 2 37-2 |
| State | Published - Feb 1995 |
| Externally published | Yes |
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Keywords
- Phospholipase C
- Sodium phosphate 4 messenger ribonucleic acid
- Transcription
- Translation
ASJC Scopus subject areas
- Physiology
- Agricultural and Biological Sciences(all)
Cite this
Epidermal growth factor inhibits Na-Pi cotransport and mRNA in OK cells. / Arar, Mazen Y; Baum, Michel; Biber, Jurg; Murer, Heini; Levi, Moshe.
In: American Journal of Physiology - Renal Fluid and Electrolyte Physiology, Vol. 268, No. 2 37-2, 02.1995.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Epidermal growth factor inhibits Na-Pi cotransport and mRNA in OK cells
AU - Arar, Mazen Y
AU - Baum, Michel
AU - Biber, Jurg
AU - Murer, Heini
AU - Levi, Moshe
PY - 1995/2
Y1 - 1995/2
N2 - The present study examined the effect of epidermal growth factor (EGF) on Na-Pi cotransport in a tubular epithelial cell line derived from the opossum kidney (OKP cells). EGF caused a time- and dose-dependent decrease in Na-Pi cotransport. The inhibition of Na-Pi cotransport by 10-8 M EGF was first demonstrable after 18 h with maximal effect seen at 24 h. EGF inhibited Na-Pi cotransport by decreasing the maximal velocity (10.8 ± 0.9 in control vs. 4.9 ± 0.8 nmol 32Pi·4 min-1·mg protein-1 in EGF, P < 0.001). Northern blot analysis indicated that EGF caused a significant decrease in NaPi-4 mRNA abundance. The abundance of NaPi-4 mRNA relative to β-actin and/or glyceraldehyde-3-phosphate dehydrogenase mRNA was decreased by twofold in OK cells treated with EGF for 4 h and threefold in OKP cells treated with EGF for 24 h. Thus the decrease in NaPi-4 mRNA abundance preceded the decrease in Na-Pi cotransport activity. Inhibition of transcription with actinomycin D and protein synthesis with cycloheximide prevented the inhibition of Na-Pi cotransport. Furthermore, inhibition of phospholipase C activity with U-73,122 also significantly blocked the inhibitory effect of EGF on Na-Pi cotransport. The results indicate that EGF-induced decrease in OKP Na-Pi cotransport is mediated through a decrease in NaPi-4 mRNA and activation of the phospholipase C signaling pathway.
AB - The present study examined the effect of epidermal growth factor (EGF) on Na-Pi cotransport in a tubular epithelial cell line derived from the opossum kidney (OKP cells). EGF caused a time- and dose-dependent decrease in Na-Pi cotransport. The inhibition of Na-Pi cotransport by 10-8 M EGF was first demonstrable after 18 h with maximal effect seen at 24 h. EGF inhibited Na-Pi cotransport by decreasing the maximal velocity (10.8 ± 0.9 in control vs. 4.9 ± 0.8 nmol 32Pi·4 min-1·mg protein-1 in EGF, P < 0.001). Northern blot analysis indicated that EGF caused a significant decrease in NaPi-4 mRNA abundance. The abundance of NaPi-4 mRNA relative to β-actin and/or glyceraldehyde-3-phosphate dehydrogenase mRNA was decreased by twofold in OK cells treated with EGF for 4 h and threefold in OKP cells treated with EGF for 24 h. Thus the decrease in NaPi-4 mRNA abundance preceded the decrease in Na-Pi cotransport activity. Inhibition of transcription with actinomycin D and protein synthesis with cycloheximide prevented the inhibition of Na-Pi cotransport. Furthermore, inhibition of phospholipase C activity with U-73,122 also significantly blocked the inhibitory effect of EGF on Na-Pi cotransport. The results indicate that EGF-induced decrease in OKP Na-Pi cotransport is mediated through a decrease in NaPi-4 mRNA and activation of the phospholipase C signaling pathway.
KW - Phospholipase C
KW - Sodium phosphate 4 messenger ribonucleic acid
KW - Transcription
KW - Translation
UR - http://www.scopus.com/inward/record.url?scp=0029159722&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029159722&partnerID=8YFLogxK
M3 - Article
C2 - 7864171
AN - SCOPUS:0029159722
VL - 268
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
SN - 0363-6127
IS - 2 37-2
ER -