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Journal of Cell Science, Vol 110, Issue 16 1967-1977, Copyright © 1997 by Company of Biologists
JOURNAL ARTICLES |
AM Alteraifi and DV Zhelev
Department of Mechanical Engineering and Materials Science, and Center for Cellular and Biosurface Engineering, LSRC, Duke University, Durham, NC 27708-0300, USA.
The release of free cytosolic calcium is a secondary messenger for many cell functions. Here we study the coupling between the release of intracellular calcium and motility responses of the human neutrophil. Two groups of motility responses are studied: motility responses in the presence of adhesion, such as cell crawling and phagocytosis, and motility responses 'in suspension', such as pseudopod formation. The motility responses are stimulated by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP) and the release of calcium is monitored by measuring the fluorescence from fluo-3. fMLP induces a single release of free cytosolic calcium both in suspended cells and in crawling cells. Calcium release is a threshold process where the number of cells releasing calcium is dependent on the chemoattractant concentration while the amount of released calcium is not. For suspended cells the threshold fMLP concentration for calcium release is in the order of 10(-7) M, while for crawling cells it is in the order of 5x10(-9) M. The smaller value of the threshold fMLP concentration for crawling cells compared to that for suspended cells suggests that bound adhesion receptors are involved in the calcium release. The threshold fMLP concentration for suspended cells is also larger than the minimum fMLP concentration (in the order of 10(-10) M) for initiating pseudopod formation. So, there is a range of fMLP concentrations where pseudopod formation occurs without calcium release. To explore this relationship further, pseudopod extension and calcium release are stimulated many times in a single cell by using fMLP concentrations above the threshold. The result is that calcium release is desensitized by fMLP while pseudopod extension is not. All the results taken together suggest that the release of free cytosolic calcium and the rearrangement of the F-actin network during motility follow different signaling pathways.
This article has been cited by other articles:
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  D. V. Zhelev, A. M. Alteraifi, and D. Chodniewicz Controlled Pseudopod Extension of Human Neutrophils Stimulated with Different Chemoattractants Biophys. J., July 1, 2004; 87(1): 688 - 695. [Abstract] [Full Text] [PDF]
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 D. Chodniewicz, A. M. Alteraifi, and D. V. Zhelev Experimental Evidence for the Limiting Role of Enzymatic Reactions in Chemoattractant-induced Pseudopod Extension in Human Neutrophils J. Biol. Chem., June 4, 2004; 279(23): 24460 - 24466. [Abstract] [Full Text] [PDF]
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 D. Chodniewicz and D. V. Zhelev Novel pathways of F-actin polymerization in the human neutrophil Blood, September 15, 2003; 102(6): 2251 - 2258. [Abstract] [Full Text] [PDF]
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D. Chodniewicz and D. V. Zhelev Chemoattractant receptor-stimulated F-actin polymerization in the human neutrophil is signaled by 2 distinct pathways Blood, February 1, 2003; 101(3): 1181 - 1184. [Abstract] [Full Text] [PDF]
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 D Wu, C. Huang, and H Jiang Roles of phospholipid signaling in chemoattractant-induced responses J. Cell Sci., January 9, 2000; 113(17): 2935 - 2940. [Abstract] [PDF]
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B. Haribabu, D. V. Zhelev, B. C. Pridgen, R. M. Richardson, H. Ali, and R. Snyderman Chemoattractant Receptors Activate Distinct Pathways for Chemotaxis and Secretion. ROLE OF G-PROTEIN USAGE J. Biol. Chem., December 24, 1999; 274(52): 37087 - 37092. [Abstract] [Full Text] [PDF]
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 E. J. PETTIT Cytosolic Free Calcium and the Cytoskeleton in the Control of Leukocyte Chemotaxis Physiol Rev, October 1, 1998; 78(4): 949 - 967. [Abstract] [Full Text] [PDF]
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