Cell Growth & Differentiation, Vol 6, Issue 9 1171-1184, Copyright © 1995 by American Association of Cancer Research

ARTICLES

Inhibitors of the intracellular Ca(2+)-ATPase in cultured mouse keratinocytes reveal components of terminal differentiation that are regulated by distinct intracellular Ca2+ compartments

L Li, RW Tucker, H Hennings and SH Yuspa
Laboratory of Cellular Carcinogenesis and Tumor Promotion, National Cancer Institute, Bethesda, Maryland 20892, USA.

Differentiation of mammalian epidermis is associated with spatially and temporally coordinated changes in gene expression as cells migrate from the proliferative basal cell compartment through the nonproliferative spinous and granular cell layers where the terminal phase of maturation is completed. Previous studies have suggested that a gradient of Ca2+ in the epidermis in vivo and increased extracellular Ca2+ in vitro induce differentiation of mammalian epidermal keratinocytes. Chelation of intracellular free Ca2+ prevents this Ca(2+)-induced differentiation, but sites of action for intracellular Ca2+ remain undefined. In this study, thapsigargin (Tg) and cyclopiazonic acid (CPA), inhibitors of the endoplasmic reticulum Ca(2+)-ATPase, were used to evaluate the relative contribution of cytoplasmic and stored Ca2+ to Ca(2+)-induced terminal differentiation of cultured mouse keratinocytes. A sustained increase of both intracellular free Ca2+ (Cai) and ionomycin-sensitive Ca2+ stores is associated with Ca(2+)-induced keratinocyte terminal differentiation. Tg and CPA was used to change this coordinated regulation of free and stored Ca2+. In the absence of extracellular Ca2+, both Tg and CPA transiently increase Cai and deplete intracellular Ca2+ stores; while in the presence of extracellular Ca2+, Tg and CPA stimulate Ca2+ influx and cause a sustained increase in Cai while depleting stored Ca2+. In the presence of extracellular Ca2+, Tg (5 to 20 nM) and CPA (5 to 25 microM) inhibit Ca(2+)-induced morphological changes and stratification and prevent the suppression of DNA synthesis by Ca2+. Tg and CPA also inhibit the expression of mRNA and protein for specific epidermal spinous cell markers, keratins 1 (K1) and 10 (K10), prevent the redistribution of E-cadherin from a diffuse membranous pattern to concentration at cell-cell junctions, and inhibit the activation of a reporter gene regulated by a K1 enhancer element shown previously to be Ca2+ sensitive. These effects of Tg and CPA can be reversed by increasing the extracellular Ca2+ to levels that partially restore Ca2+ stores. In contrast, Tg and CPA enhance the expression of profilaggrin and loricrin mRNA and protein, markers of granular cell differentiation. These divergent actions of Tg and CPA on distinct components of the keratinocyte differentiation program suggest that adequate intracellular Ca2+ stores are important for the expression of spinous cell proteins and inhibition of DNA synthesis, while elevation of Cai stimulates the expression of markers of granular cell differentiation.

This article has been cited by other articles:

				C.-L. Tu, W. Chang, Z. Xie, and D. D. Bikle Inactivation of the Calcium Sensing Receptor Inhibits E-cadherin-mediated Cell-Cell Adhesion and Calcium-induced Differentiation in Human Epidermal Keratinocytes J. Biol. Chem., February 8, 2008; 283(6): 3519 - 3528. [Abstract] [Full Text] [PDF]

				K. Ridd, S.-D. Zhang, R. E. Edwards, R. Davies, P. Greaves, A. Wolfreys, A. G. Smith, and T. W. Gant Association of gene expression with sequential proliferation, differentiation and tumor formation in murine skin Carcinogenesis, August 1, 2006; 27(8): 1556 - 1566. [Abstract] [Full Text] [PDF]

				L. Foggia, I. Aronchik, K. Aberg, B. Brown, A. Hovnanian, and T. M. Mauro Activity of the hSPCA1 Golgi Ca2+ pump is essential for Ca2+-mediated Ca2+ response and cell viability in Darier disease J. Cell Sci., February 15, 2006; 119(4): 671 - 679. [Abstract] [Full Text] [PDF]

				L. Li, K. Sampat, N. Hu, J. Zakari, and S. H. Yuspa Protein Kinase C Negatively Regulates Akt Activity and Modifies UVC-induced Apoptosis in Mouse Keratinocytes J. Biol. Chem., February 10, 2006; 281(6): 3237 - 3243. [Abstract] [Full Text] [PDF]

				S. Balasubramanian, M. T. Sturniolo, G. R. Dubyak, and R. L. Eckert Human epidermal keratinocytes undergo (-)-epigallocatechin-3-gallate-dependent differentiation but not apoptosis Carcinogenesis, June 1, 2005; 26(6): 1100 - 1108. [Abstract] [Full Text] [PDF]

				S. Krisanaprakornkit, D. Jotikasthira, and B.A. Dale Intracellular Calcium in Signaling Human {beta}-Defensin-2 Expression in Oral Epithelial Cells J. Dent. Res., November 1, 2003; 82(11): 877 - 882. [Abstract] [Full Text] [PDF]

				Y.-S. Seong, C. Min, L. Li, J. Y. Yang, S.-Y. Kim, X. Cao, K. Kim, S. H. Yuspa, H.-H. Chung, and K. S. Lee Characterization of a Novel Cyclin-Dependent Kinase 1 Inhibitor, BMI-1026 Cancer Res., November 1, 2003; 63(21): 7384 - 7391. [Abstract] [Full Text] [PDF]

				Y. Katsu, D. B. Lubahn, and T. Iguchi Expression of a Novel C-Type Lectin in the Mouse Vagina Endocrinology, June 1, 2003; 144(6): 2597 - 2605. [Abstract] [Full Text] [PDF]

				W. Ahn, M. G. Lee, K. H. Kim, and S. Muallem Multiple Effects of SERCA2b Mutations Associated with Darier's Disease J. Biol. Chem., May 30, 2003; 278(23): 20795 - 20801. [Abstract] [Full Text] [PDF]

				A. Deucher, T. Efimova, and R. L. Eckert Calcium-dependent Involucrin Expression Is Inversely Regulated by Protein Kinase C (PKC)alpha and PKCdelta J. Biol. Chem., May 3, 2002; 277(19): 17032 - 17040. [Abstract] [Full Text] [PDF]

				H. Fan and P. A. Khavari Sonic Hedgehog Opposes Epithelial Cell Cycle Arrest J. Cell Biol., October 4, 1999; 147(1): 71 - 76. [Abstract] [Full Text] [PDF]

				Z. Nemes, L. N. Marekov, and P. M. Steinert Involucrin Cross-linking by Transglutaminase 1. BINDING TO MEMBRANES DIRECTS RESIDUE SPECIFICITY J. Biol. Chem., April 16, 1999; 274(16): 11013 - 11021. [Abstract] [Full Text] [PDF]

				D. S. Keeney, C. Skinner, J. B. Travers, J. H. Capdevila, L. B. Nanney, L. E. King Jr., and M. R. Waterman Differentiating Keratinocytes Express a Novel Cytochrome P450 Enzyme, CYP2B19, Having Arachidonate Monooxygenase Activity J. Biol. Chem., November 27, 1998; 273(48): 32071 - 32079. [Abstract] [Full Text] [PDF]

				L. H. Liu, G. P. Boivin, V. Prasad, M. Periasamy, and G. E. Shull Squamous Cell Tumors in Mice Heterozygous for a Null Allele of Atp2a2, Encoding the Sarco(endo)plasmic Reticulum Ca2+-ATPase Isoform 2 Ca2+ Pump J. Biol. Chem., July 13, 2001; 276(29): 26737 - 26740. [Abstract] [Full Text] [PDF]

				D. C. Ng, S. Shafaee, D. Lee, and D. D. Bikle Requirement of an AP-1 Site in the Calcium Response Region of the Involucrin Promoter J. Biol. Chem., July 28, 2000; 275(31): 24080 - 24088. [Abstract] [Full Text] [PDF]