Regulation of endoplasmic reticulum-Ca-ATPase by glycolysis in eukaryotic cells.
This paper reviews work by our and other laboratories that explores the coupling between glycolysis and endoplasmic reticulum (ER)-Ca-ATPases in regulating Ca2+ homeostasis in several cell types. Changes in intracellular Ca2+ [(Ca2+]in) link interaction between hormones and cell surface receptors with the initiation of specific cellular functions. Thus, changes in [Ca2+]in mediate signal transduction mechanisms that modulate many physiological functions including cell growth, muscle cell contractility, and exocytosis in secretory cells. In most eukaryotic cells, total cellular Ca2+ is in the millimolar range, yet only a fraction (i.e., nanomolar) is free in the cytosol. Cells use both active and 'passive' mechanisms to maintain [Ca2+]in within a narrow range. Active mechanisms include plasma membrane and endoplasmic/sarcoplasmic reticulum (ER/SR)-Ca-ATPases, Ca2+ channels (inositol trisphosphate- and voltage-sensitive), and Na+/Ca2+ exchangers. 'Passive' mechanisms include Ca(2+)-binding proteins (e.g., calsequestrin, calmodulin, calreticulin). The relative contribution of active and 'passive' mechanisms to [Ca2+]in homeostasis in a given cell is not known. Ca2+ might move among several intracellular compartments, including the ER/SR, mitochondria, nucleus, Golgi apparatus, endosomes and lysosomes. The ubiquitous distribution of ER-Ca-ATPases in these intracellular organelles suggests a major role of this pump in Ca2+ homeostasis, but the importance of intracellular compartments to [Ca2+]in homeostasis is not well understood. Glucose has been suggested to have a role in regulating some of these ion transport processes. Thus, the increased cell metabolism that follows glucose stimulation is associated with altered [Ca2+]in homeostasis. The precise mechanisms by which glucose or its metabolites modulate [Ca2+]in homeostasis are unknown but might involve regulation of ER-Ca-ATPases.
Martínez-Zaguilán
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Department of Physiology, Texas Tech University Health Sciences Center, Lubbock 79430, USA.
Wesson
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D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D005057:Eukaryotic Cells / Q000201:enzymology*; D005947:Glucose / Q000502:physiology; D006019:Glycolysis; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D007211:Indoles / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007425:Intracellular Membranes / Q000378:metabolism; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D019284:Thapsigargin / Q000494:pharmacology
D007211:Indoles; D007328:Insulin; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D005947:Glucose; D002118:Calcium; C000543:cyclopiazonic acid