Calcium-channel activation and matrix protein upregulation in bone cells in response to mechanical strain

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Calcium-channel activation and matrix protein upregulation in bone cells in response to mechanical strain. / Walker, L M; Publicover, S J; Preston, M R; Said Ahmed, M A; El Haj, A J.

In: Journal of Cellular Biochemistry, Vol. 79, No. 4, 14.09.2000, p. 648-61.

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@article{ee1fe3e4cc064f5a9e473ad36812f798,
title = "Calcium-channel activation and matrix protein upregulation in bone cells in response to mechanical strain",
abstract = "Femur-derived osteoblasts cultured from rat femora were loaded with Fluo-3 using the AM ester. A quantifiable stretch was applied and [Ca(2+)]i levels monitored by analysis of fluorescent images obtained using an inverted microscope and laser scanning confocal imaging system. Application of a single pulse of tensile strain via an expandable membrane resulted in immediate increase in [Ca(2+)]i in a proportion of the cells, followed by a slow and steady decrease to prestimulation levels. Application of parathyroid hormone (10(-6) M) prior to mechanical stimulation potentiated the load-induced elevation of [Ca(2+)]i. Mechanically stimulating osteoblasts in Ca(2+)-free media or in the presence of either nifedipine (10 microM; L-type Ca(2+)-channel blocker) or thapsigargin (1 microM; depletes intracellular Ca(2+) stores) reduced strain-induced increases in [Ca(2+) ]i. Furthermore, strain-induced increases in [Ca(2+)]i were enhanced in the presence of Bayer K 8644 (500 nm), an agonist of L-type calcium channels. The effects of mechanical strain with and without inhibitors and agonists are described on the total cell population and on single cell responses. Application of strain and strain in the presence of the calcium-channel agonist Bay K 8644 to periosteal-derived osteoblasts increased levels of the extracellular matrix proteins osteopontin and osteocalcin within 24 h postload. This mechanically induced increase in osteopontin and osteocalcin was inhibited by the addition of the calcium-channel antagonist, nifedipine. Our results suggest an important role for L-type calcium channels and a thapsigargin-sensitive component in early mechanical strain transduction pathways in osteoblasts.",
keywords = "Sialoglycoproteins, Animals, Calcium, Osteocalcin, Parathyroid Hormone, Calcium Channels, Rats, Osteoblasts, Thapsigargin, Cells, Cultured, Stress, Mechanical, Osteopontin, Bone Matrix",
author = "Walker, {L M} and Publicover, {S J} and Preston, {M R} and {Said Ahmed}, {M A} and {El Haj}, {A J}",
note = "Copyright 2000 Wiley-Liss, Inc.",
year = "2000",
month = sep,
day = "14",
language = "English",
volume = "79",
pages = "648--61",
journal = "Journal of Cellular Biochemistry",
issn = "0730-2312",
publisher = "Wiley",
number = "4",

}

RIS

TY - JOUR

T1 - Calcium-channel activation and matrix protein upregulation in bone cells in response to mechanical strain

AU - Walker, L M

AU - Publicover, S J

AU - Preston, M R

AU - Said Ahmed, M A

AU - El Haj, A J

N1 - Copyright 2000 Wiley-Liss, Inc.

PY - 2000/9/14

Y1 - 2000/9/14

N2 - Femur-derived osteoblasts cultured from rat femora were loaded with Fluo-3 using the AM ester. A quantifiable stretch was applied and [Ca(2+)]i levels monitored by analysis of fluorescent images obtained using an inverted microscope and laser scanning confocal imaging system. Application of a single pulse of tensile strain via an expandable membrane resulted in immediate increase in [Ca(2+)]i in a proportion of the cells, followed by a slow and steady decrease to prestimulation levels. Application of parathyroid hormone (10(-6) M) prior to mechanical stimulation potentiated the load-induced elevation of [Ca(2+)]i. Mechanically stimulating osteoblasts in Ca(2+)-free media or in the presence of either nifedipine (10 microM; L-type Ca(2+)-channel blocker) or thapsigargin (1 microM; depletes intracellular Ca(2+) stores) reduced strain-induced increases in [Ca(2+) ]i. Furthermore, strain-induced increases in [Ca(2+)]i were enhanced in the presence of Bayer K 8644 (500 nm), an agonist of L-type calcium channels. The effects of mechanical strain with and without inhibitors and agonists are described on the total cell population and on single cell responses. Application of strain and strain in the presence of the calcium-channel agonist Bay K 8644 to periosteal-derived osteoblasts increased levels of the extracellular matrix proteins osteopontin and osteocalcin within 24 h postload. This mechanically induced increase in osteopontin and osteocalcin was inhibited by the addition of the calcium-channel antagonist, nifedipine. Our results suggest an important role for L-type calcium channels and a thapsigargin-sensitive component in early mechanical strain transduction pathways in osteoblasts.

AB - Femur-derived osteoblasts cultured from rat femora were loaded with Fluo-3 using the AM ester. A quantifiable stretch was applied and [Ca(2+)]i levels monitored by analysis of fluorescent images obtained using an inverted microscope and laser scanning confocal imaging system. Application of a single pulse of tensile strain via an expandable membrane resulted in immediate increase in [Ca(2+)]i in a proportion of the cells, followed by a slow and steady decrease to prestimulation levels. Application of parathyroid hormone (10(-6) M) prior to mechanical stimulation potentiated the load-induced elevation of [Ca(2+)]i. Mechanically stimulating osteoblasts in Ca(2+)-free media or in the presence of either nifedipine (10 microM; L-type Ca(2+)-channel blocker) or thapsigargin (1 microM; depletes intracellular Ca(2+) stores) reduced strain-induced increases in [Ca(2+) ]i. Furthermore, strain-induced increases in [Ca(2+)]i were enhanced in the presence of Bayer K 8644 (500 nm), an agonist of L-type calcium channels. The effects of mechanical strain with and without inhibitors and agonists are described on the total cell population and on single cell responses. Application of strain and strain in the presence of the calcium-channel agonist Bay K 8644 to periosteal-derived osteoblasts increased levels of the extracellular matrix proteins osteopontin and osteocalcin within 24 h postload. This mechanically induced increase in osteopontin and osteocalcin was inhibited by the addition of the calcium-channel antagonist, nifedipine. Our results suggest an important role for L-type calcium channels and a thapsigargin-sensitive component in early mechanical strain transduction pathways in osteoblasts.

KW - Sialoglycoproteins

KW - Animals

KW - Calcium

KW - Osteocalcin

KW - Parathyroid Hormone

KW - Calcium Channels

KW - Rats

KW - Osteoblasts

KW - Thapsigargin

KW - Cells, Cultured

KW - Stress, Mechanical

KW - Osteopontin

KW - Bone Matrix

M3 - Article

C2 - 10996855

VL - 79

SP - 648

EP - 661

JO - Journal of Cellular Biochemistry

JF - Journal of Cellular Biochemistry

SN - 0730-2312

IS - 4

ER -