Protein Kinase C α Modulates the Ca2+ Influx Phase of the Ca2+ Response to 1α,25-Dihydroxy-Vitamin-D3 in Skeletal Muscle Cells
- 1 April 2001
- journal article
- research article
- Published by Georg Thieme Verlag KG in Hormone and Metabolic Research
- Vol. 33 (4) , 201-206
- https://doi.org/10.1055/s-2001-14950
Abstract
Treatment of chick skeletal muscle cells with 1α,25-dihydroxy-vitamin D3 [1α,25(OH)2D3] triggers a rapid and sustained increase in cytosolic Ca2+ ([Ca2+]i), which depends on Ca2+ mobilization from inner stores and extracellular Ca2+ entry. Fluorimetric analysis of changes in [Ca2+]i in Fura-2-loaded cells revealed that the hormone significantly stimulates the Ca2+ influx phase within the concentration range of 10-12 - 10-6 M, with maximal effects (3.5-fold increase) at 10-9 M 1α,25(OH)2D3. The effects of the sterol on the Ca2+ entry pathway were abolished by the PKC inhibitors bisindolylmaleimide and calphostin. We have recently shown that, in these cells, 1α,25(OH)2D3 activates and translocates PKC α to the membrane, suggesting that this isozyme accounts for PKC-dependent 1α,25(OH)2D3 modulation of Ca2+ entry. The role of PKC α was specifically addressed here using antisense technology. When the expression of PKC α was selectively knocked out by intranuclear microinjection of an antisense oligonucleotide against PKC α mRNA, the Ca2+ influx component of the response to 1α,25(OH)2D3 was markedly reduced (- 60 %). These results demonstrate that 1α,25(OH)2D3-induced activation of PKC α enhances extracellular Ca2+ entry partially contributing to maintainance of the sustained phase of the Ca2+ response to the sterol.Keywords
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