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Parathormone sensitivity and responses to protein kinases in subclones of opossum kidney cells

Douglas M Silverstein1, Adrian Spitzer, Mario Barac-Nieto

  • 1Division of Nephrology, Department of Pediatrics, Health Sciences Center, Louisiana State University, New Orleans, 70118, USA. dsilve@lsuhsc.edu

Pediatric Nephrology (Berlin, Germany)
|April 19, 2005
PubMed

Insights

Parathyroid hormone (PTH) and protein kinase (PK) effectors differentially regulate sodium-dependent phosphate (Na-Pi) transport in opossum kidney (OK) cells. This study reveals functional heterogeneity in OK cell responses to these regulators.

Area of Science:

  • Nephrology
  • Cell Physiology
  • Molecular Biology

Background:

  • Parathyroid hormone (PTH) is known to inhibit renal sodium-dependent phosphate (Na-Pi) cotransport.
  • This inhibition involves protein kinases A (PKA) and C (PKC), and 20-hydroxyeicosatetraneoic acid (20-HETE).
  • Variability in reported effects suggests functional heterogeneity among opossum kidney (OK) cell subclones.

Purpose of the Study:

  • To investigate the effect of PTH and PK effectors on Na-Pi transport in distinct sets of OK cells.
  • To explore the functional heterogeneity of OK cells in response to Na-Pi transport regulators.

Main Methods:

  • Two separate groups of OK cells, derived from the same stock, were used.
  • Cells were treated with PTH, 20-HETE, TPA (a PKC activator), and staurosporine (a PKC inhibitor).
  • Sodium- and phosphate (Na-(32)Pi) transport was measured using radiolabeled phosphate uptake.

Main Results:

  • Group 1 OK cells showed inhibition of Na-Pi transport by 20-HETE, PTH, TPA, and Br-cAMP.
  • Group 2 OK cells exhibited increased Na-Pi transport with 20-HETE and TPA, while PTH had no significant effect.
  • PKC inhibition with staurosporine increased Na-Pi transport in Group 1, but slightly decreased it in Group 2, with simultaneous 20-HETE restoring baseline in both.

Conclusions:

  • OK cell subclones demonstrate markedly different responses to regulators of Na-Pi cotransport.
  • Functional heterogeneity exists within OK cell populations, impacting their response to hormonal and signaling pathways.
  • These findings highlight the importance of considering cell subclone variability in renal phosphate transport studies.

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