Abstract
Ryanodine receptor subtype 1 (RyR1) has been primarily characterized in skeletal muscle but several studies have revealed its expression in smooth muscle. Here, we used Ryr1-null mice to investigate the role of this isoform in Ca2+ signaling in urinary bladder smooth muscle. We show that RyR1 is required for depolarization-induced Ca2+ sparks, whereas RyR2 and RyR3 are sufficient for spontaneous or caffeine-induced Ca2+ sparks. Immunostaining revealed specific subcellular localization of RyR1 in the superficial sarcoplasmic reticulum; by contrast, RyR2 and RyR3 are mainly expressed in the deep sarcoplasmic reticulum. Paradoxically, lack of depolarization-induced Ca2+ sparks in Ryr1-/ - myocytes was accompanied by an increased number of cells displaying spontaneous or depolarization-induced Ca2+ waves. Investigation of protein expression showed that FK506-binding protein (FKBP) 12 and FKBP12.6 (both of which are RyR-associated proteins) are downregulated in Ryr1-/- myocytes, whereas expression of RyR2 and RyR3 are unchanged. Moreover, treatment with rapamycin, which uncouples FKBPs from RyR, led to an increase of RyR-dependent Ca2+ signaling in wild-type urinary bladder myocytes but not in Ryr1-/- myocytes. In conclusion, although decreased amounts of FKBP increase Ca2+ signals in Ryr1-/- urinary bladder myocytes the depolarization-induced Ca2+ sparks are specifically lost, demonstrating that RyR1 is required for depolarization-induced Ca2+ sparks and suggesting that the intracellular localization of RyR1 fine-tunes Ca2+ signals in smooth muscle.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3784-3791 |
| Number of pages | 8 |
| Journal | Journal of Cell Science |
| Volume | 120 |
| Issue number | 21 |
| DOIs | |
| State | Published - Nov 1 2007 |
| Externally published | Yes |
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Keywords
- Ca sparks
- FK506-binding protein
- Ryanodine receptors
- Ryr1 mice
- Smooth muscle
ASJC Scopus subject areas
- Cell Biology
Cite this
RyR1-specific requirement for depolarization-induced Ca2+ sparks in urinary bladder smooth muscle. / Fritz, Nicolas; Morel, Jean Luc; Jeyakumar, Loice H.; Fleischer, Sidney; Allen, Paul D.; Mironneau, Jean; Macrez, Nathalie.
In: Journal of Cell Science, Vol. 120, No. 21, 01.11.2007, p. 3784-3791.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - RyR1-specific requirement for depolarization-induced Ca2+ sparks in urinary bladder smooth muscle
AU - Fritz, Nicolas
AU - Morel, Jean Luc
AU - Jeyakumar, Loice H.
AU - Fleischer, Sidney
AU - Allen, Paul D.
AU - Mironneau, Jean
AU - Macrez, Nathalie
PY - 2007/11/1
Y1 - 2007/11/1
N2 - Ryanodine receptor subtype 1 (RyR1) has been primarily characterized in skeletal muscle but several studies have revealed its expression in smooth muscle. Here, we used Ryr1-null mice to investigate the role of this isoform in Ca2+ signaling in urinary bladder smooth muscle. We show that RyR1 is required for depolarization-induced Ca2+ sparks, whereas RyR2 and RyR3 are sufficient for spontaneous or caffeine-induced Ca2+ sparks. Immunostaining revealed specific subcellular localization of RyR1 in the superficial sarcoplasmic reticulum; by contrast, RyR2 and RyR3 are mainly expressed in the deep sarcoplasmic reticulum. Paradoxically, lack of depolarization-induced Ca2+ sparks in Ryr1-/ - myocytes was accompanied by an increased number of cells displaying spontaneous or depolarization-induced Ca2+ waves. Investigation of protein expression showed that FK506-binding protein (FKBP) 12 and FKBP12.6 (both of which are RyR-associated proteins) are downregulated in Ryr1-/- myocytes, whereas expression of RyR2 and RyR3 are unchanged. Moreover, treatment with rapamycin, which uncouples FKBPs from RyR, led to an increase of RyR-dependent Ca2+ signaling in wild-type urinary bladder myocytes but not in Ryr1-/- myocytes. In conclusion, although decreased amounts of FKBP increase Ca2+ signals in Ryr1-/- urinary bladder myocytes the depolarization-induced Ca2+ sparks are specifically lost, demonstrating that RyR1 is required for depolarization-induced Ca2+ sparks and suggesting that the intracellular localization of RyR1 fine-tunes Ca2+ signals in smooth muscle.
AB - Ryanodine receptor subtype 1 (RyR1) has been primarily characterized in skeletal muscle but several studies have revealed its expression in smooth muscle. Here, we used Ryr1-null mice to investigate the role of this isoform in Ca2+ signaling in urinary bladder smooth muscle. We show that RyR1 is required for depolarization-induced Ca2+ sparks, whereas RyR2 and RyR3 are sufficient for spontaneous or caffeine-induced Ca2+ sparks. Immunostaining revealed specific subcellular localization of RyR1 in the superficial sarcoplasmic reticulum; by contrast, RyR2 and RyR3 are mainly expressed in the deep sarcoplasmic reticulum. Paradoxically, lack of depolarization-induced Ca2+ sparks in Ryr1-/ - myocytes was accompanied by an increased number of cells displaying spontaneous or depolarization-induced Ca2+ waves. Investigation of protein expression showed that FK506-binding protein (FKBP) 12 and FKBP12.6 (both of which are RyR-associated proteins) are downregulated in Ryr1-/- myocytes, whereas expression of RyR2 and RyR3 are unchanged. Moreover, treatment with rapamycin, which uncouples FKBPs from RyR, led to an increase of RyR-dependent Ca2+ signaling in wild-type urinary bladder myocytes but not in Ryr1-/- myocytes. In conclusion, although decreased amounts of FKBP increase Ca2+ signals in Ryr1-/- urinary bladder myocytes the depolarization-induced Ca2+ sparks are specifically lost, demonstrating that RyR1 is required for depolarization-induced Ca2+ sparks and suggesting that the intracellular localization of RyR1 fine-tunes Ca2+ signals in smooth muscle.
KW - Ca sparks
KW - FK506-binding protein
KW - Ryanodine receptors
KW - Ryr1 mice
KW - Smooth muscle
UR - http://www.scopus.com/inward/record.url?scp=36549006968&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=36549006968&partnerID=8YFLogxK
U2 - 10.1242/jcs.009415
DO - 10.1242/jcs.009415
M3 - Article
C2 - 17925380
AN - SCOPUS:36549006968
VL - 120
SP - 3784
EP - 3791
JO - Journal of Cell Science
JF - Journal of Cell Science
SN - 0021-9533
IS - 21
ER -