Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The vacuolar H(+)-ATPase (V-ATPase) mediates ATP-driven H(+) transport across membranes. This pump is present at the apical membrane of kidney proximal tubule cells and intercalated cells. Defects in the V-ATPase and in proximal tubule function can cause renal tubular acidosis. We examined the role of protein kinase A (PKA) and AMP-activated protein kinase (AMPK) in the regulation of the V-ATPase in the proximal tubule as these two kinases coregulate the V-ATPase in the collecting duct. As the proximal tubule V-ATPases have different subunit compositions from other nephron segments, we postulated that V-ATPase regulation in the proximal tubule could differ from other kidney tubule segments. Immunofluorescence labeling of rat ex vivo kidney slices revealed that the V-ATPase was present in the proximal tubule both at the apical pole, colocalizing with the brush-border marker wheat germ agglutinin, and in the cytosol when slices were incubated in buffer alone. When slices were incubated with a cAMP analog and a phosphodiesterase inhibitor, the V-ATPase accumulated at the apical pole of S3 segment cells. These PKA activators also increased V-ATPase apical membrane expression as well as the rate of V-ATPase-dependent extracellular acidification in S3 cell monolayers relative to untreated cells. However, the AMPK activator AICAR decreased PKA-induced V-ATPase apical accumulation in proximal tubules of kidney slices and decreased V-ATPase activity in S3 cell monolayers. Our results suggest that in proximal tubule the V-ATPase subcellular localization and activity are acutely coregulated via PKA downstream of hormonal signals and via AMPK downstream of metabolic stress.
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PMID:Regulation of proximal tubule vacuolar H(+)-ATPase by PKA and AMP-activated protein kinase. 2455 31

Apremilast is a recently developed phosphodiesterase 4-inhibitory medication approved for use to treat psoriasis and psoriatic arthritis. We report a case of Fanconi syndrome and proximal renal tubular acidosis that was associated with this medication. Our patient was started on treatment with apremilast 2 weeks before his admission. On arrival, laboratory test results were significant for hypokalemia, hyperchloremic metabolic acidosis, low uric acid concentration, positive urine anion gap, and proteinuria, which resolved on discontinuation of the drug. Two months after the hospitalization, he was restarted on apremilast therapy; 17 days after resumption, the patient was admitted for similar laboratory values, which again improved when apremilast treatment was discontinued. After discharge, laboratory values remained normal without long-term electrolyte repletion. Proximal renal tubular acidosis (Fanconi syndrome) with quick correction of electrolyte concentrations on discontinuation of the drug was diagnosed. Our patient lacked evidence of other causes. Our patient fulfilled criteria associated with this disease and responded well off treatment with the offending agent. Literature review did not reveal prior cases associated with this medication.
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PMID:Proximal Renal Tubular Acidosis (Fanconi Syndrome) Induced by Apremilast: A Case Report. 2882 83