Homeostatic calcium fluxes, ER calcium release, SOCE, and calcium oscillations in cultured astrocytes are interlinked by a small calcium toolkit

To elucidate new functions of sphingosine (Sph), we demonstrate that the spontaneous elevation of intracellular Sph levels via caged Sph leads to a significant and transient calcium release from acidic stores that is independent of sphingosine 1-phosphate, extracellular and ER calcium levels. This photo-induced Sph-driven calcium release requires the two-pore channel 1 (TPC1) residing on endosomes and lysosomes. Further, uncaging of Sph leads to the translocation of the autophagy-relevant transcription factor EB (TFEB) to the nucleus specifically after lysosomal calcium release. We confirm that Sph accumulates in late endosomes and lysosomes of cells derived from Niemann-Pick disease type C (NPC) patients and demonstrate a greatly reduced calcium release upon Sph uncaging. We conclude that sphingosine is a positive regulator of calcium release from acidic stores and that understanding the interplay between Sph homeostasis, calcium signaling and autophagy will be crucial in developing new therapies for lipid storage disorders such as NPC.

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Involvement of c-Fos in signaling grp78 induction following ER calcium release

Oncogene ◽

10.1038/sj.onc.1203994 ◽

2000 ◽

Vol 19 (51) ◽

pp. 5936-5943 ◽

Cited By ~ 16

Author(s):

Huiling He ◽

Karen McColl ◽

Clark W Distelhorst

Keyword(s):

Calcium Release ◽

Er Calcium

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On the origin of rhythmic calcium transients in the ICC-MP of the mouse small intestine

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00077.2011 ◽

2011 ◽

Vol 301 (5) ◽

pp. G835-G845 ◽

Cited By ~ 28

Author(s):

Bobbi-Jo Lowie ◽

Xuan-Yu Wang ◽

Elizabeth J. White ◽

Jan D. Huizinga

Keyword(s):

Small Intestine ◽

Calcium Channel ◽

Calcium Release ◽

Imaging Study ◽

Cyclopiazonic Acid ◽

Calcium Oscillations ◽

Calcium Transients ◽

Pacemaker Activity ◽

Type I ◽

Endoplasmic Reticulum Calcium

Interstitial cells of Cajal associated with the myenteric plexus (ICC-MP) are pacemaker cells of the small intestine, producing the characteristic omnipresent electrical slow waves, which orchestrate peristaltic motor activity and are associated with rhythmic intracellular calcium oscillations. Our objective was to elucidate the origins of the calcium transients. We hypothesized that calcium oscillations in the ICC-MP are primarily regulated by the sarcoplasmic reticulum (SR) calcium release system. With the use of calcium imaging, study of the effect of T-type calcium channel blocker mibefradil revealed that T-type channels did not play a major role in generating the calcium transients. 2-Aminoethoxydiphenyl borate, an inositol 1,4,5 trisphosphate receptor (IP3R) inhibitor, and U73122, a phospholipase C inhibitor, both drastically decreased the frequency of calcium oscillations, suggesting a major role of IP3 and IP3-induced calcium release from the SR. Immunohistochemistry proved the expression of IP3R type I (IP3R-I), but not type II (IP3R-II) and type III (IP3R-III) in ICC-MP, indicating the involvement of the IP3R-I subtype in calcium release from the SR. Cyclopiazonic acid, a SR/endoplasmic reticulum calcium ATPase pump inhibitor, strongly reduced or abolished calcium oscillations. The Na-Ca exchanger (NCX) in reverse mode is likely involved in refilling the SR because the NCX inhibitor KB-R7943 markedly reduced the frequency of calcium oscillations. Immunohistochemistry revealed 100% colocalization of NCX and c-Kit in ICC-MP. Testing a mitochondrial NCX inhibitor, we were unable to show an essential role for mitochondria in regulating calcium oscillations in the ICC-MP. In summary, ongoing IP3 synthesis and IP3-induced calcium release from the SR, via the IP3R-I, are the major drivers of the calcium transients associated with ICC pacemaker activity. This suggests that a biochemical clock intrinsic to ICC determines the pacemaker frequency, which is likely directly linked to kinetics of the IP3-activated SR calcium channel and IP3 metabolism.

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2161Redox-mediated PKA-RIalpha localisation to the lysosome inhibits myocardial calcium release and robustly reduces myocardial injury

European Heart Journal ◽

10.1093/eurheartj/ehz748.0091 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

J N Simon ◽

B Vrellaku ◽

S Monterisi ◽

S Chu ◽

N Rawlings ◽

...

Keyword(s):

Calcium Release ◽

Super Resolution ◽

Left Ventricular ◽

Calcium Oscillations ◽

Pore Channel ◽

Calcium Stores ◽

Channel Inhibition ◽

Anchoring Proteins ◽

Concomitant Reduction ◽

Novel Target

Abstract Background Kinase oxidation is a critical signalling mechanism through which changes in the intracellular redox state alter cardiac function. In the myocardium, type-1 protein kinase A (PKARIα) can be reversibly oxidised, forming interprotein disulphide bonds within the holoenzyme complex. However, the effect of PKARIα oxidation on downstream signalling in the heart, particularly under states of oxidative stress, remains unexplored. Purpose To determine the direct functional consequences of PKARIα oxidation in the heart and investigate their impact on ischaemia/reperfusion (I/R) injury. Methods and results Experiments using the AKAR3ev FRET biosensor in murine left ventricular (LV) myocytes and Fluorescence Recovery After Photobleaching (FRAP) of GFP-tagged wild-type (WT) and mutant RIα proteins expressed in RIα-null fibroblasts showed that PKARIα oxidation does not increase the kinases' catalytic activity, but enhances its binding to A-kinase anchoring proteins (AKAP; n=30–39/N=3, p<0.01). Super-resolution microscopy revealed localisation of oxidised PKARIα to lysosomes in WT myocytes, which was completely absent in “redox dead” Cys17Ser PKARIα knock-in mice (KI; panel A; n=38–41/N=3, p<0.01) and reduced when AKAP binding was prevented using the RIAD disruptor peptide (30.6±5.1% reduction; n=35–37/N=3, p<0.01). Displacement of PKARIα from lysosomes resulted in spontaneous sarcoplasmic reticulum calcium release and dramatic calcium oscillations in KI LV myocytes (panel B), which were preventable by ryanodine receptor blockade (1 mM tetracaine; n=14, p<0.01), acute depletion of endolysosomal calcium stores (100 nM bafilomycin; n=7; p<0.01), or lysosomal two-pore channel inhibition (5 μM Ned-19; n=9; p<0.05). I/R (secondary to cardiopulmonary bypass) was found to induce PKARIα oxidation in the myocardium of patients undergoing cardiac surgery (panel C; n=18, p<0.05). Absence of this response in KI mouse hearts resulted in 2-fold larger infarcts (p<0.01) and a concomitant reduction in LV contractile recovery (final LVDP of 55.9±8.6 vs 82.5±7.1 mmHg in WT; n=7–8, p<0.05), both which were prevented by addition of Ned-19 at the time of reperfusion (panel D; n=4, p<0.01). Conclusions Oxidised PKARIα acts as a potent inhibitor of intracellular calcium release in the heart through its redox-dependent interaction with the lysosome. In the setting of I/R, where PKARIα oxidation is induced, this regulatory mechanism is critical for protecting the heart from injury and offers a novel target for the design of cardioprotective therapeutics. Acknowledgement/Funding British Heart Foundation CH/12/3/29609, RG/16/12/32451; Garfield-Weston Foundation MPS/IVIMS-11/12-4032; Wellcome Trust Fellowship 0998981Z/12/Z

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Spatiotemporal dynamics of intracellular [Ca2+]i oscillations during the growth and meiotic maturation of mouse oocytes

Development ◽

10.1242/dev.120.12.3507 ◽

1994 ◽

Vol 120 (12) ◽

pp. 3507-3517 ◽

Cited By ~ 3

Author(s):

J. Carroll ◽

K. Swann ◽

D. Whittingham ◽

M. Whitaker

Keyword(s):

Spatial Organization ◽

Calcium Release ◽

Calcium Oscillations ◽

Meiotic Maturation ◽

Similar Proportion ◽

Calcium Waves ◽

Apparent Difference ◽

Immature Oocytes ◽

Mouse Oocytes

Calcium oscillations occur during meiotic maturation of mouse oocytes. They also trigger activation at fertilization. We have monitored [Ca2+]i in oocytes at different stages of growth and maturation to examine how the calcium release mechanisms alter during oogenesis. Spontaneous calcium oscillations occur every 2–3 minutes in the majority of fully grown (but immature) mouse oocytes released from antral follicles and resuming meiosis. The oscillations last for 2–4 hours after release from the follicle and take the form of global synchronous [Ca2+]i increases throughout the cell. Rapid image acquisition or cooling the bath temperature from 28 degrees C to 16 degrees C did not reveal any wave-like spatial heterogeneity in the [Ca2+]i signal. Calcium appears to reach highest levels in the germinal vesicle but this apparent difference of [Ca2+] in nucleus and cytoplasm is an artifact of dye loading. Smaller, growing immature oocytes are less competent: about 40% are able to resume meiosis and a similar proportion of these oocytes show spontaneous calcium oscillations. [Ca2+]i transients are not seen in oocytes that do not resume meiosis spontaneously in vitro. Nonetheless, these oocytes are capable of [Ca2+]i oscillations since they show them in response to the addition of carbachol or thimerosal. To examine how the properties of calcium release change during meiotic maturation, a calcium-releasing factor from sperm was microinjected into fully grown immature and mature oocytes. The sperm-factor-induced oscillations were about two-fold larger and longer in mature oocytes compared to immature oocytes. Calcium waves travelling at 40–60 microns/second were generated in mature oocytes, but not in immature oocytes. In some mature oocytes, successive calcium waves had different sites of origin. The modifications in the size and spatial organization of calcium transients during oocyte maturation may be a necessary prerequisite for normal fertilization.

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NF-κB activated by ER calcium release inhibits Aβ-mediated expression of CHOP protein: Enhancement by AD-linked mutant presenilin 1

Experimental Neurology ◽

10.1016/j.expneurol.2007.04.009 ◽

2007 ◽

Vol 208 (2) ◽

pp. 169-176 ◽

Cited By ~ 22

Author(s):

Jason Schapansky ◽

Kelly Olson ◽

Randy Van Der Ploeg ◽

Gordon Glazner

Keyword(s):

Calcium Release ◽

Presenilin 1 ◽

Er Calcium

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Laser backscatter studies of intracellular Ca2+ oscillations in isolated hearts

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1989.257.2.h665 ◽

1989 ◽

Vol 257 (2) ◽

pp. H665-H673 ◽

Cited By ~ 2

Author(s):

M. D. Stern ◽

H. F. Weisman ◽

D. G. Renlund ◽

G. Gerstenblith ◽

O. Hano ◽

...

Keyword(s):

Intracellular Calcium ◽

Calcium Release ◽

Scattered Light ◽

Calcium Oscillations ◽

Extracellular Potassium ◽

Base Line ◽

Measured Intensity ◽

Isolated Hearts ◽

Rat Hearts ◽

Intensity Fluctuations

We measured intensity fluctuations of 633 nm laser light backscattered from the epicardial surface of isolated, perfused rat and rabbit hearts. Scattered light intensity fluctuations (SLIF) were detected from verapamil-arrested rat hearts. The frequency of SLIF was increased by maneuvers that raise intracellular calcium. SLIF were abolished by removal of extracellular calcium with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and by blockade of sarcoplasmic reticulum calcium release by ryanodine. SLIF were not accompanied by any surface electro-cardiogram and were not abolished by 144 mM extracellular potassium. SLIF were absent in rabbit hearts under base-line conditions but could be provoked by calcium loading using zero potassium and ouabain. We conclude that backscatter SLIF monitor the microscopic motion caused by intracellular calcium oscillations in the intact heart. We measured SLIF from rat hearts during 60 min of global ischemia at 30 degrees C, followed by reflow. Ischemia reduced SLIF frequency to zero within 30 min. Reflow caused an overshoot of SLIF frequency to as much as five times control, suggesting that reflow causes major calcium overload of cells that are at least transiently viable.

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