scholarly journals Parathyroid Hormone (PTH) decreases mRNA stability of the Type IIa Sodium‐Phosphate Cotransporter (NpT2a)

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Rebecca Murray ◽  
Nina Lesousky ◽  
Syed Jalal Khundmiri ◽  
Barbara Clark ◽  
Eleanor Lederer
Keyword(s):  
Parathyroid Hormone ◽  
Mrna Stability ◽  
Sodium Phosphate

scholarly journals Symptomatic Hypocalcemia due to Sodium Phosphate for Bowel Preparation following Minimally Invasive Parathyroidectomy

2011 ◽  
Vol 3 (2) ◽  
pp. 91-92
Author(s):  
Turkay Kirdak ◽  
Nusret Korun
Keyword(s):  
Parathyroid Hormone ◽  
Primary Hyperparathyroidism ◽  
Minimally Invasive ◽  
Serum Calcium ◽  
Bowel Preparation ◽  
Sodium Phosphate ◽  
Minimally Invasive Parathyroidectomy ◽  
Invasive Parathyroidectomy ◽  
Symptomatic Hypocalcemia ◽  
Carpopedal Spasm

ABSTRACT This paper presents a case on symptomatic hypocalcemia due to sodium phosphate use for bowel preparation following parathyroidectomy. Serum calcium and parathyroid hormone were in normal levels postoperatively. Two months following the operation, phosphosoda was administered for bowel preparation. Following bowel preparation severe carpopedal spasm developed. It can be speculated that sodium phosphate administration for bowel preparation may precipitate hypocalcemic tetany in the patients undergoing parathyroidectomy for primary hyperparathyroidism.

Acute regulation of parathyroid hormone by dietary phosphate

2005 ◽  
Vol 289 (4) ◽  
pp. E729-E734 ◽  
Author(s):  
Daniel R. Martin ◽  
Cynthia S. Ritter ◽  
Eduardo Slatopolsky ◽  
Alex J. Brown
Keyword(s):  
Renal Failure ◽  
Parathyroid Hormone ◽  
Sodium Phosphate ◽  
Total Plasma ◽  
Plasma Phosphate ◽  
Serum Parathyroid Hormone ◽  
Additional Signal ◽  
Dietary Phosphate ◽  
Single Meal

Secondary hyperparathyroidism in chronic renal failure is stimulated by dietary phosphate (Pi) loading and ameliorated by dietary Pi restriction. We investigated the rapidity of the response of serum parathyroid hormone (PTH) to changes in dietary Pi. When uremic rats adapted to a high Pi diet (HPD) were fed a single meal of low Pi diet (LPD), plasma PTH fell 80% within 2 h; plasma Pi fell 1 mg/dl with no change in plasma ionized Ca (ICa). When uremic rats on the HPD were gavaged with LPD, PTH fell 60% within 15 min; plasma Pi fell by 3.0 mg/dl with no change in total plasma Ca. However, HPD gavage increased PTH by 80% within 15 min with no change in plasma P or Ca, suggesting that the response may be independent of altered plasma Pi. Duodenal infusion of sodium Pi increased PTH twofold within 10 min, with no change in ICa but an increase in plasma Pi, whereas duodenal infusion of NaCl had no effect on any of these parameters. Intravenous infusion of sodium phosphate also increased PTH within 10 min with no change in plasma ICa; intravenous NaCl had no effect. Additionally, duodenal infusion of phosphonoformate, a nonabsorbable phosphate analog, increased PTH fourfold within 5 min, but did not change plasma P or ICa. These findings indicate that oral Pi increases PTH release in vivo more rapidly than previously reported; this response may be from both plasma phosphate and an additional signal arising from the gastrointestinal tract.

scholarly journals Cisandtransacting factors in the regulation of parathyroid hormone (PTH) mRNA stability by calcium and phosphate

FEBS Letters ◽  
2002 ◽  
Vol 529 (1) ◽  
pp. 60-64 ◽  
Author(s):  
Tally Naveh-Many ◽  
Osnat Bell ◽  
Justin Silver ◽  
Rachel Kilav
Keyword(s):  
Parathyroid Hormone ◽  
Mrna Stability

scholarly journals Epidermal growth factor-stimulated parathyroid hormone-related protein expression involves increased gene transcription and mRNA stability

1995 ◽  
Vol 307 (1) ◽  
pp. 159-167 ◽  
Author(s):  
J K Heath ◽  
J Southby ◽  
S Fukumoto ◽  
L M O'Keeffe ◽  
T J Martin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Parathyroid Hormone ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Gene Transcription ◽  
Mrna Stability ◽  
Specific Effect ◽  
Related Protein ◽  
Parathyroid Hormone Related Protein ◽  
Epidermal Growth

Epidermal growth factor (EGF) produced rapid and striking effects on parathyroid hormone-related protein (PTHrP) gene expression in the immortalized human keratinocyte cell line, HaCaT. Steady-state levels of PTHrP mRNA and secreted PTHrP were increased 10-fold by maximally effective concentrations of EGF. EGF increased both PTHrP gene transcription and PTHrP mRNA stability. Nuclear run-on assays demonstrated a 4-fold increase in transcriptional rate in EGF-stimulated cells while transient transfection analysis indicated that the action of EGF on transcription involved both the GC-rich promoter, P2, and the downstream TATA promoter, P3, but apparently not the upstream TATA promoter, P1. In experiments where EGF treatment produced more stable PTHrP transcripts, the half-life of c-fos mRNA was unaltered, suggesting a relatively specific effect of EGF. Moreover, only those species of PTHrP mRNA containing two of the alternative 3′ exons (exons VII and VIII) were stable, those containing exon IX were not. Reverse-transcription PCR demonstrated that EGF produced differential increases in the abundance of PTHrP mRNA species initiated by the three PTHrP promoters. The major effect was seen on the abundance of transcripts initiated by P1 and P2, with less marked regulation of P3-initiated transcripts. Thus EGF regulation of PTHrP gene expression in HaCaT cells is multifactorial and the combination of its actions at the 5′ and 3′ ends of the gene favours the accumulation of subpopulations of PTHrP mRNA containing exons I, VII and VIII.

scholarly journals Differential modulation of the molecular dynamics of the type IIa and IIc sodium phosphate cotransporters by parathyroid hormone

2011 ◽  
Vol 301 (4) ◽  
pp. C850-C861 ◽  
Author(s):  
Luca Lanzano ◽  
Tim Lei ◽  
Kayo Okamura ◽  
Hector Giral ◽  
Yupanqui Caldas ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Proximal Tubule ◽  
Sodium Phosphate ◽  
Time Course ◽  
Apical Membrane ◽  
Response Times ◽  
Complete Removal ◽  
Myosin Vi ◽  
The Difference ◽  
Renal Proximal Tubule Cells

The kidney is a key regulator of phosphate homeostasis. There are two predominant renal sodium phosphate cotransporters, NaPi2a and NaPi2c. Both are regulated by parathyroid hormone (PTH), which decreases the abundance of the NaPi cotransporters in the apical membrane of renal proximal tubule cells. The time course of PTH-induced removal of the two cotransporters from the apical membrane, however, is markedly different for NaPi2a compared with NaPi2c. In animals and in cell culture, PTH treatment results in almost complete removal of NaPi2a from the brush border (BB) within 1 h whereas for NaPi2c this process in not complete until 4 to 8 h after PTH treatment. The reason for this is poorly understood. We have previously shown that the unconventional myosin motor myosin VI is required for PTH-induced removal of NaPi2a from the proximal tubule BB. Here we demonstrate that myosin VI is also necessary for PTH-induced removal of NaPi2c from the apical membrane. In addition, we show that, while at baseline the two cotransporters have similar diffusion coefficients within the membrane, after PTH addition the diffusion coefficient for NaPi2a initially exceeds that for NaPi2c. Thus NaPi2c appears to remain “tethered” in the apical membrane for longer periods of time after PTH treatment, accounting, at least in part, for the difference in response times to PTH of NaPi2a versus NaPi2c.

scholarly journals Ezrin promotes functional expression and parathyroid hormone-mediated regulation of the sodium-phosphate cotransporter 2a in LLC-PK1 cells

2008 ◽  
Vol 294 (3) ◽  
pp. F667-F675 ◽  
Author(s):  
Matthew J. Mahon
Keyword(s):  
Parathyroid Hormone ◽  
Sodium Phosphate ◽  
Phosphate Uptake ◽  
Functional Expression ◽  
Dominant Negative ◽  
Early Passage ◽  
Membrane Expression ◽  
Activated State ◽  
Sodium Hydrogen Exchanger ◽  
Endocytic Vesicles

The sodium-phosphate cotransporter 2a (NPT2a) is the principal phosphate transporter expressed in the brush border of renal proximal tubules and is downregulated by parathyroid hormone (PTH) through an endocytic mechanism. Apical membrane expression of NPT2a is dependent on interactions with the sodium-hydrogen exchanger regulatory factor 1 (NHERF-1). An LLC-PK1 renal cell line stably expressing the PTH receptor (PTH1R) and NHERF-1, termed B28-N1, fails to functionally express NPT2a. In B28-N1 cells, NHERF-1 and NPT2a are inappropriately localized to the cytoplasm. Ezrin, in the activated state, is capable at linking NHERF-1-assembled complexes to the actin cytoskeleton. Early-passage LLC-PK1 cells stably transfected with either empty vector or wild-type ezrin express a comparable level of the active, T567 phosphorylated form of ezrin and are capable of functionally expressing NPT2a. Colocalization of the PTH1R, NPT2a, and ezrin exists and is prominently associated with actin-containing microvilli in apical domains of these cells. Upon PTH treatment, the PTH1R, NPT2a, NHERF-1, and ezrin colocalize to endocytic vesicles and NPT2a-dependent phosphate uptake is markedly inhibited. LLC-PK1 cells expressing the constitutively active ezrin (T567D) display enhanced NPT2a functional expression and PTH-mediated regulation of phosphate. Expression of a dominant-negative ezrin, consisting of the NH2-terminal half of the protein, markedly disrupts NPT2a-dependent phosphate uptake. PTH does not appear to alter ezrin phosphorylation at T567. Instead, PTH perhaps initiates NPT2a endocytosis by inducing reorganization of the actin-containing microvilli in a process that is blocked by the actin-stabilizing compound jasplakinolide.

Sign in / Sign up

Export Citation Format

Share Document