Publications by authors named "Rajatsubhra Biswas"

Fibroblast growth factor-23 (FGF-23) inhibits sodium-dependent phosphate transport in brush border membrane vesicles derived from hormone-treated kidney slices of the mouse and in mouse proximal tubule cells by processes involving mitogen-activated protein kinase (MAPK) but not protein kinase A (PKA) or protein kinase C (PKC). By contrast, phosphate transport in brush border membrane vesicles and proximal tubule cells from sodium-hydrogen exchanger regulatory factor-1 (NHERF-1)-null mice were resistant to the inhibitory effect of FGF-23 (10(-9) m). Infection of NHERF-1-null proximal tubule cells with wild-type adenovirus-GFP-NHERF-1 increased basal phosphate transport and restored the inhibitory effect of FGF-23.

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The current experiments explore the role of dopamine in facilitating the acute increase in renal phosphate excretion in response to a high-phosphate diet. Compared with a low-phosphate (0.1%) diet for 24 h, mice fed a high-phosphate (1.

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Article Synopsis
  • Eukaryotic cells utilize a specialized organization of signaling components to respond to hormones and growth factors, involving the formation of multiprotein complexes.
  • The PDZ domain is the most prevalent protein interaction domain in eukaryotes, with over 500 identified, and PDZ-containing proteins like NHERF play crucial roles in cell function regulation.
  • This review emphasizes NHERF-1's role as a prototypical PDZ protein, particularly its involvement in phosphate transport and the development of certain types of kidney stones (nephrolithiasis).
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Article Synopsis
  • The phosphorylation of NHERF-1, particularly at Ser(77) and Thr(95), is crucial for regulating how the kidneys handle phosphate in response to hormones like parathyroid hormone (PTH) and dopamine.
  • Mutating Thr(95) to alanine impairs the phosphorylation of Ser(77), leading to a loss of hormonal inhibition on phosphate transport, while the presence of active NHERF-1 restores this inhibition.
  • The study highlights that phosphorylation of Thr(95) is essential for the subsequent phosphorylation of Ser(77), which ultimately decreases phosphate transport by allowing NHERF-1 to detach from the phosphate transporter Npt2a.
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Dopamine inhibited phosphate transport in isolated renal brush border membrane vesicles and in cultured renal proximal tubule cells from wild-type but not from NHERF-1 null mice. Co-immunoprecipitation experiments established that NHERF-1 associated with D1-like receptors. In wild-type mice, dopamine stimulated cAMP accumulation and protein kinase C (PKC) activity in renal proximal tubule cells, an effect that was abolished by SCH-23390, a D1-like receptor antagonist.

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Article Synopsis
  • The experiments investigated how phosphate transport in cultured mouse proximal tubule cells is influenced by parathyroid hormone (PTH), dopamine, and various signaling molecules.
  • Both PTH and dopamine were found to decrease phosphate transport by over 30%, with the effect of PTH being dependent on protein kinase C (PKC) activation, while dopamine's effect involved both PKC and protein kinase A (PKA) pathways.
  • The study concluded that there are distinct signaling mechanisms for PTH and dopamine in regulating phosphate transport, and that MAPK activation does not play a critical role in this inhibition.
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There is increasing evidence that mammalian urinary tract epithelial cells utilize membrane channels and transporters to transport solutes across their apical (luminal) and basalateral membranes to modify solute concentrations in both cell and urine. This study investigates the expression, localization, and regulation of the ROMK (K(ir) 1.1) potassium channels in rat and dog ureter and bladder tissues.

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