Multiple effects of econazole on calcium signaling: depletion of thapsigargin-sensitive calcium store, activation of extracellular calcium influx, and inhibition of capacitative calcium entry

Dysregulation of calcium signaling has been causally implicated in brain aging and Alzheimer's disease. Mutations in the presenilin genes (PS1, PS2), the leading cause of autosomal dominant familial Alzheimer's disease (FAD), cause highly specific alterations in intracellular calcium signaling pathways that may contribute to the neurodegenerative and pathological lesions of the disease. To elucidate the cellular mechanisms underlying these disturbances, we studied calcium signaling in fibroblasts isolated from mutant PS1 knockin mice. Mutant PS1 knockin cells exhibited a marked potentiation in the amplitude of calcium transients evoked by agonist stimulation. These cells also showed significant impairments in capacitative calcium entry (CCE, also known as store-operated calcium entry), an important cellular signaling pathway wherein depletion of intracellular calcium stores triggers influx of extracellular calcium into the cytosol. Notably, deficits in CCE were evident after agonist stimulation, but not if intracellular calcium stores were completely depleted with thapsigargin. Treatment with ionomycin and thapsigargin revealed that calcium levels within the ER were significantly increased in mutant PS1 knockin cells. Collectively, our findings suggest that the overfilling of calcium stores represents the fundamental cellular defect underlying the alterations in calcium signaling conferred by presenilin mutations.

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Capacitative calcium entry

The Journal of Cell Biology ◽

10.1083/jcb.200503161 ◽

2005 ◽

Vol 169 (3) ◽

pp. 381-382 ◽

Cited By ~ 122

Author(s):

James W. Putney

Keyword(s):

Plasma Membrane ◽

Calcium Binding ◽

Cell Biology ◽

Essential Role ◽

Calcium Entry ◽

Calcium Stores ◽

Capacitative Calcium Entry ◽

Calcium Store ◽

Channel Regulation ◽

Calcium Channel Regulation

A long-standing mystery in the cell biology of calcium channel regulation is the nature of the signal linking intracellular calcium stores to plasma membrane capacitative calcium entry channels. An RNAi-based screen of selected Drosophila genes has revealed that a calcium-binding protein, stromal interaction molecule (STIM), plays an essential role in the activation of these channels and may be the long sought sensor of calcium store content.

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Capacitative calcium entry is colocalised with calcium release in Xenopus oocytes: Evidence against a highly diffusible calcium influx factor

Pflügers Archiv - European Journal of Physiology ◽

10.1007/s004240050135 ◽

1996 ◽

Vol 432 (2) ◽

pp. 286-292 ◽

Cited By ~ 50

Author(s):

Carl C. H. Petersen ◽

Michael J. Berridge

Keyword(s):

Xenopus Oocytes ◽

Calcium Release ◽

Calcium Influx ◽

Calcium Entry ◽

Capacitative Calcium Entry

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Effect of Elevated Glucose on Endothelin-Induced Store-Operated and Non-Store-Operated Calcium Influx in Renal Mesangial Cells

Journal of the American Society of Nephrology ◽

10.1681/asn.v1171225 ◽

2000 ◽

Vol 11 (7) ◽

pp. 1225-1235

Author(s):

LETA K. NUTT ◽

ROGER G. O'NEIL

Keyword(s):

Calcium Signaling ◽

High Glucose ◽

Mesangial Cells ◽

Calcium Influx ◽

Calcium Entry ◽

Calcium Signal ◽

Glomerular Mesangial Cells ◽

Glucose Levels ◽

Elevated Glucose ◽

Acute And Chronic Exposure

Abstract. Early diabetic nephropathy exhibits renal glomerular hyperfiltration and an increase in renal plasma flow. The hyperfiltration is a dysfunctional state that may arise from a hyperglycemic-induced hypocontractility of glomerular mesangial cells that may be associated with depressed Ca2+signaling events. The present study was designed to determine the effects of acute (minutes) and chronic (days) elevated glucose levels on endothelin-induced calcium signaling with a particular emphasis on the potential influence on stores and store-operated Ca2+influx (SOCI ; also called capacitative calcium entry) in glomerular mesangial cells. Primary cultures of rat mesangial cells were grown in either high (30 mM) or normal (5 mM) glucose-containing media and tested in the presence of either high (30 mM) or normal (5 mM) glucose levels. Intracellular calcium levels were monitored with the calcium-sensitive fluorophore fura-2 before and after treatment with either endothelin-1 (10 nM), to induce typical Ca2+signals, or the endoplasmic reticulum (ER) Ca-ATPase inhibitor thapsagargin (1 μM), to unload ER Ca2+stores. Both acute and chronic exposure to high glucose levels depressed the endothelin-induced calcium signal. However, neither release of Ca2+from stores nor SOCI were depressed by high glucose levels. In contrast, an endothelin-induced calcium entry pathway (likely receptor-operated calcium influx), separate from SOCI, was markedly depressed in the presence of both acute and chronic high glucose levels. The depressant effect of high glucose was rapidly (minutes) reversible upon returning to normal glucose levels. It is concluded that high glucose levels depress endothelin-induced calcium signaling in rat mesangial cells by inhibiting non-SOCI Ca2+entry pathways, namely the receptor-operated Ca2+influx pathway. The glucose-induced alterations in the receptor-operated calcium influx pathway may, in part, contribute to the depressed contractile state of glomerular cells during periods of hyperglycemia.

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Absence of blocking effects on cardiac slow calcium channels by the intracellular calcium antagonist 2-n-propyl-3-dimethylamino-5,6-methylenedioxyindene

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y82-117 ◽

1982 ◽

Vol 60 (6) ◽

pp. 841-849 ◽

Cited By ~ 10

Author(s):

Joseph J. Lynch ◽

Ralf G. Rahwan

Keyword(s):

Calcium Antagonist ◽

Calcium Channels ◽

Calcium Channel ◽

Calcium Influx ◽

Negative Inotropic Effect ◽

Calcium Entry ◽

Extracellular Calcium ◽

Myocardial Cells ◽

Inotropic Effects ◽

Site Of Action

Extensive pharmacological evidence supports the contention that 2-n-propyl-3-dimcthylamino-5,6-methylenedioxyindene hydrochloride (pr-MDI) is a calcium antagonist with a predominantly intracellular site of action. On the other hand, electrophysiological evidence points to a possible membrane slow inward calcium channel blocking property of this agent. To gain further insight as to the site of action of pr-MDI, the interactions between the negative inotropic action of this agent and the positive inotropic actions of excess extracellular calcium (which directly penetrates the myocardial cells through the slow calcium channels), isoproterenol (which indirectly augments calcium influx through the slow calcium channels), and ouabain (which enhances calcium influx through membrane calcium entry routes distinct from the slow calcium channels) were investigated in the isolated, electrically driven guinea pig left atrium. Although excess extracellular calcium, isoproterenol, and ouabain reversed the negative inotropic effect of pr-MDI, an analysis of the concentration–response relationships to all three positive inotropic agents in the presence and the absence of pr-MDI demonstrated that this agent did not significantly inhibit the contractile effects of calcium, isoproterenol, or ouabain, at pr-MDI concentrations which exhibit intrinsic negative inotropic effects. It is concluded that pr-MDI does not block the membrane slow inward calcium channel nor other presumptive membrane routes of calcium entry into myocardial cells at concentrations of 10−4 M or less. At very high concentrations (T × 10−4 M) some inhibition of slow channel calcium influx may occur.

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