TY - JOUR
T1 - Hormonally-regulated expression of voltage-operated Ca²⁺ channels in osteocytic (MLO-Y4) cells
AU - Gu, Yuchun
AU - Preston, MR
AU - Magnay, J
AU - El Haj, AJ
AU - Publicover, Stephen
PY - 2001/3/30
Y1 - 2001/3/30
N2 - Voltage operated calcium channels (VOCCs) are important in stimulus-response coupling in osteoblasts. We have investigated the expression of VOCCs in the mouse osteocyte cell line, MLO-Y4. Using the whole-cell patch clamp technique we were unable to detect any VOCC currents (n = 436) even in the presence of the L-type VOCC agonist Bay K 8644 (n = 350). Reverse transcription polymerase chain reaction (RT-PCR), using primers to detect alpha(1C), alpha(1D), and alpha(1G) VOCC subunits (all of which are expressed in primary osteoblasts), did not generate detectable products with mRNA from MLO-Y4 cells. However, after treatment with physiological levels of hormones, VOCC alpha(1) subunit mRNAs were detected in MLO-Y4 cells. PTH, 17beta-estradiol, and dexamethasone-treatment induced expression of L-type (alpha(1C), alpha(1D)) subunit transcripts. ATP-treatment induced expression of T-type (alpha(1G)) transcripts. Using whole-cell patch clamp we detected VOCC currents in 5-10% of cells after treatment. Current characteristics (L- or T-type) were consistent with the transcript expressed.
AB - Voltage operated calcium channels (VOCCs) are important in stimulus-response coupling in osteoblasts. We have investigated the expression of VOCCs in the mouse osteocyte cell line, MLO-Y4. Using the whole-cell patch clamp technique we were unable to detect any VOCC currents (n = 436) even in the presence of the L-type VOCC agonist Bay K 8644 (n = 350). Reverse transcription polymerase chain reaction (RT-PCR), using primers to detect alpha(1C), alpha(1D), and alpha(1G) VOCC subunits (all of which are expressed in primary osteoblasts), did not generate detectable products with mRNA from MLO-Y4 cells. However, after treatment with physiological levels of hormones, VOCC alpha(1) subunit mRNAs were detected in MLO-Y4 cells. PTH, 17beta-estradiol, and dexamethasone-treatment induced expression of L-type (alpha(1C), alpha(1D)) subunit transcripts. ATP-treatment induced expression of T-type (alpha(1G)) transcripts. Using whole-cell patch clamp we detected VOCC currents in 5-10% of cells after treatment. Current characteristics (L- or T-type) were consistent with the transcript expressed.
KW - oestradiol
KW - bone
KW - PTH
KW - deamethasone
KW - ATP
KW - osteocyte
KW - MLO-Y4
KW - voltage-operated Ca2+ channel
UR - http://www.scopus.com/inward/record.url?scp=0034806057&partnerID=8YFLogxK
U2 - 10.1006/bbrc.2001.4615
DO - 10.1006/bbrc.2001.4615
M3 - Article
C2 - 11401493
VL - 282
SP - 536
EP - 542
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -