Interaction of the smooth endoplasmic reticulum and mitochondria

2006 ◽  
Vol 34 (3) ◽  
pp. 370-373 ◽  
Author(s):  
J.G. Goetz ◽  
I.R. Nabi
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Cytosolic Calcium ◽  
Functional Roles ◽  
Calcium Dependent ◽  
Motility Factor ◽  
Calcium Sequestration ◽  
Multiple Domains ◽  
The Relationship

The ER (endoplasmic reticulum) is composed of multiple domains including the nuclear envelope, ribosome-studded rough ER and the SER (smooth ER). The SER can also be functionally segregated into domains that regulate ER–Golgi traffic (transitional ER), ERAD (ER-associated degradation), sterol and lipid biosynthesis and calcium sequestration. The last two, as well as apoptosis, are critically regulated by the close association of the SER with mitochondria. Studies with AMFR (autocrine motility factor receptor) have defined an SER domain whose integrity and mitochondrial association can be modulated by ilimaquinone as well as by free cytosolic calcium levels in the normal physiological range. AMFR is an E3 ubiquitin ligase that targets its ligand directly to the SER via a caveolae/raft-dependent pathway. In the present review, we will address the relationship between the calcium-dependent morphology and mitochondrial association of the SER and its various functional roles in the cell.

scholarly journals Calcium Regulates the Association between Mitochondria and a Smooth Subdomain of the Endoplasmic Reticulum

2000 ◽  
Vol 150 (6) ◽  
pp. 1489-1498 ◽  
Author(s):  
Hui-Jun Wang ◽  
Ginette Guay ◽  
Liviu Pogan ◽  
Remy Sauvé ◽  
Ivan R. Nabi
Keyword(s):  
Confocal Microscopy ◽  
Mdck Cells ◽  
Close Association ◽  
Cytosolic Calcium ◽  
Free Calcium ◽  
Autocrine Motility Factor ◽  
Cytosolic Free Calcium ◽  
Motility Factor ◽  
Rat Liver Cytosol ◽  
Close Contacts

Association between the ER and mitochondria has long been observed, and the formation of close contacts between ER and mitochondria is necessary for the ER-mediated sequestration of cytosolic calcium by mitochondria. Autocrine motility factor receptor (AMF-R) is a marker for a smooth subdomain of the ER, shown here by confocal microscopy to be distinct from, yet closely associated with the calnexin- or calreticulin-labeled ER. By EM, smooth ER AMF-R tubules exhibit direct interactions with mitochondria, identifying them as a mitochondria-associated smooth ER subdomain. In digitonin-permeabilized MDCK cells, the addition of rat liver cytosol stimulates the dissociation of smooth ER and mitochondria under conditions of low calcium. Using BAPTA chelators of various affinities and CaEGTA buffers of defined free Ca2+ concentrations and quantitative confocal microscopy, we show that free calcium concentrations <100 nM favor dissociation, whereas those >1 μM favor close association between these two organelles. Therefore, we describe a cellular mechanism that facilitates the close association of this smooth ER subdomain and mitochondria when cytosolic free calcium rises above physiological levels.

scholarly journals Localization of Calcium in the Smooth Endoplasmic Reticulum of Rat Isolated Fat Cells

1974 ◽  
Vol 15 (1) ◽  
pp. 1-15
Author(s):  
C. N. HALES ◽  
J. P. LUZIO ◽  
J. A. CHANDLER ◽  
L. HERMAN
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Fat Cells ◽  
Fat Cell ◽  
Interconnected System ◽  
Sodium Magnesium ◽  
Lipid Mass ◽  
Lipolytic Hormones ◽  
Potassium Pyroantimonate

The cytoplasm of the rat isolated fat cell contains a highly organized, interconnected system of smooth endoplasmic reticulum having close association with the central lipid mass, mitochondria and cytoplasmic lipid droplets. Elements of smooth endoplasmic reticulum approach, but do not fuse with, the plasma membrane. When fat cells were treated with potassium pyroantimonate during fixation for electron microscopy a precipitate was produced inside the smooth endoplasmic reticulum. Analysis with an AEI-EMMA 4 analytical electron microscope showed that the precipitate contained calcium but not sodium, magnesium or manganese. It is possible that the smooth endoplasmic reticulum of fat cells may be structurally and functionally analogous to the sarcoplasmic reticulum in skeletal muscle, and that redistribution of calcium from a calcium store inside the smooth endoplasmic reticulum may be a consequence of the action of lipolytic hormones.

A quantitative morphological study of the pineal organ in the goldfish, Carassius auratus

1981 ◽  
Vol 59 (7) ◽  
pp. 1312-1325 ◽  
Author(s):  
John A. McNulty
Keyword(s):  
Endoplasmic Reticulum ◽  
Pineal Organ ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Photoreceptor Cells ◽  
Nerve Fibers ◽  
Substantial Part ◽  
Electron Microscopic ◽  
Goldfish Carassius Auratus ◽  
Supportive Cells

Stereological techniques applied to a light and electron microscopic study of the pineal organ of the goldfish indicated that photoreceptor and supportive cells were comparable in their number and cell volume and that approximately 500 nerve cells were present in the pineal end vesicle. There were approximately 310 nerve fibers descending the distal part of the pineal tract. Quantitative analysis of organelles in photoreceptor cells revealed that the endoplasmic reticulum and Golgi bodies, in the vicinity of which were situated both clear and dense-cored vesicles, formed a substantial part of the cytoplasmic volume. Other new observations reported for this species include a close association between mitochondria and parts of the smooth endoplasmic reticulum, a characteristic feature of photoreceptor cells, and the presence of subsurface cisternae formed from profiles of endoplasmic reticulum. Moreover, specialized contacts were found between both photoreceptor and supportive cells. Some of these ultrastructural features are similar to those reported in the secretory pinealocytes of mammals. These findings suggest that (1) the pineal organ in this species has a high degree of photosensitivity as evidenced by the large number of photoreceptor cells related to each nerve cell, and (2) photoreceptor cells are metabolically active possibly having functions other than photoreception.

scholarly journals Localization of Autocrine Motility Factor Receptor to Caveolae and Clathrin-independent Internalization of Its Ligand to Smooth Endoplasmic Reticulum

1998 ◽  
Vol 9 (7) ◽  
pp. 1773-1786 ◽  
Author(s):  
Naciba Benlimame ◽  
Phuong U. Le ◽  
Ivan R. Nabi
Keyword(s):  
Endoplasmic Reticulum ◽  
Confocal Microscopy ◽  
Cell Surface ◽  
Smooth Endoplasmic Reticulum ◽  
Fluid Phase ◽  
Cell Surface Receptor ◽  
Tubular Structures ◽  
Autocrine Motility Factor ◽  
Motility Factor ◽  
3T3 Fibroblasts

Autocrine motility factor receptor (AMF-R) is a cell surface receptor that is also localized to a smooth subdomain of the endoplasmic reticulum, the AMF-R tubule. By postembedding immunoelectron microscopy, AMF-R concentrates within smooth plasmalemmal vesicles or caveolae in both NIH-3T3 fibroblasts and HeLa cells. By confocal microscopy, cell surface AMF-R labeled by the addition of anti-AMF-R antibody to viable cells at 4°C exhibits partial colocalization with caveolin, confirming the localization of cell surface AMF-R to caveolae. Labeling of cell surface AMF-R by either anti-AMF-R antibody or biotinylated AMF (bAMF) exhibits extensive colocalization and after a pulse of 1–2 h at 37°C, bAMF accumulates in densely labeled perinuclear structures as well as fainter tubular structures that colocalize with AMF-R tubules. After a subsequent 2- to 4-h chase, bAMF is localized predominantly to AMF-R tubules. Cytoplasmic acidification, blocking clathrin-mediated endocytosis, results in the essentially exclusive distribution of internalized bAMF to AMF-R tubules. By confocal microscopy, the tubular structures labeled by internalized bAMF show complete colocalization with AMF-R tubules. bAMF internalized in the presence of a 10-fold excess of unlabeled AMF labels perinuclear punctate structures, which are therefore the product of fluid phase endocytosis, but does not label AMF-R tubules, demonstrating that bAMF targeting to AMF-R tubules occurs via a receptor-mediated pathway. By electron microscopy, bAMF internalized for 10 min is located to cell surface caveolae and after 30 min is present within smooth and rough endoplasmic reticulum tubules. AMF-R is therefore internalized via a receptor-mediated clathrin-independent pathway to smooth ER. The steady state localization of AMF-R to caveolae implicates these cell surface invaginations in AMF-R endocytosis.

scholarly journals Sorcin is an early marker of neurodegeneration, Ca2+ dysregulation and endoplasmic reticulum stress associated to neurodegenerative diseases

2020 ◽  
Vol 11 (10) ◽  
Author(s):  
Ilaria Genovese ◽  
Flavia Giamogante ◽  
Lucia Barazzuol ◽  
Theo Battista ◽  
Annarita Fiorillo ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Neurodegenerative Diseases ◽  
Calcium Binding ◽  
Cytosolic Calcium ◽  
Sigma 1 Receptor ◽  
Calcium Dependent ◽  
Early Marker ◽  
Sigma 1 ◽  
Stress Dependent ◽  
Er Calcium

Abstract Dysregulation of calcium signaling is emerging as a key feature in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD), and targeting this process may be therapeutically beneficial. Under this perspective, it is important to study proteins that regulate calcium homeostasis in the cell. Sorcin is one of the most expressed calcium-binding proteins in the human brain; its overexpression increases endoplasmic reticulum (ER) calcium concentration and decreases ER stress in the heart and in other cellular types. Sorcin has been hypothesized to be involved in neurodegenerative diseases, since it may counteract the increased cytosolic calcium levels associated with neurodegeneration. In the present work, we show that Sorcin expression levels are strongly increased in cellular, animal, and human models of AD, PD, and HD, vs. normal cells. Sorcin partially colocalizes with RyRs in neurons and microglia cells; functional experiments with microsomes containing high amounts of RyR2 and RyR3, respectively, show that Sorcin is able to regulate these ER calcium channels. The molecular basis of the interaction of Sorcin with RyR2 and RyR3 is demonstrated by SPR. Sorcin also interacts with other ER proteins as SERCA2 and Sigma-1 receptor in a calcium-dependent fashion. We also show that Sorcin regulates ER calcium transients: Sorcin increases the velocity of ER calcium uptake (increasing SERCA activity). The data presented here demonstrate that Sorcin may represent both a novel early marker of neurodegenerative diseases and a response to cellular stress dependent on neurodegeneration.

Regulation of cholecystokinin secretion by ATP-sensitive potassium channels

1994 ◽  
Vol 267 (4) ◽  
pp. G595-G600 ◽  
Author(s):  
A. W. Mangel ◽  
V. Prpic ◽  
N. D. Snow ◽  
S. Basavappa ◽  
L. J. Hurst ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Potassium Channel ◽  
Intestinal Secretion ◽  
Cytosolic Calcium ◽  
Channel Activity ◽  
Calcium Dependent ◽  
Relationship Of ◽  
The Relationship ◽  
Potassium Channel Activity ◽  
Cck Release

The relationship of potassium channel activity to the secretion of cholecystokinin (CCK) was evaluated in STC-1 cells, an intestinal CCK-secreting cell line. Patch-clamp and 86Rb efflux studies showed that an ATP-sensitive potassium channel was endogenously expressed in STC-1 cells. Furthermore, channels are present in sufficient number to significantly modulate whole cell potassium permeability after either channel activation or closure with diazoxide (100 microM) or disopyramide (200 microM), respectively. Inhibition of channel activity with glucose (5-20 mM) was found to depolarize the plasma membrane, increase cytosolic calcium levels, and stimulate CCK release. Glucose-mediated release of CCK, as well as the increase in cytosolic calcium, was inhibited by the calcium channel blocker diltiazem (10 microM). It is concluded that intestinal secretion of CCK may be tonically controlled by activity of basally active ATP-sensitive potassium channels, and after inhibition of channel activity, calcium-dependent CCK secretion is stimulated.

scholarly journals Smooth Endoplasmic Reticulum Clusters in Oocytes From Patients Who Received Intracytoplasmic Sperm Injections Negatively Affect Blastocyst Quality and Speed of Blastocyst Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Xue Wang ◽  
YaLing Xiao ◽  
ZhengYi Sun ◽  
JingRan Zhen ◽  
Qi Yu
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Multiple Logistic Regression Analysis ◽  
Fertilization Rate ◽  
Multiple Logistic Regression ◽  
Blastocyst Development ◽  
Significant Difference ◽  
Blastocyst Quality ◽  
Blastocyst Rate ◽  
The Relationship

Findings regarding the relationship between smooth endoplasmic reticulum clusters (SERCs) in oocytes and blastocyst development have been conflicting. In this study, the effects of SERCs on blastocyst quality and the speed of blastocyst development were evaluated. Patients who received intracytoplasmic sperm injections (ICSI) at our reproductive center from 2016 to 2020 were retrospectively analyzed. SERC (+) oocytes (n = 217) and SERC (–) oocytes (n = 822), as well as SERC (+) cycles (n = 146) and SERC (–) cycles (n = 1,951) were compared. There was no significant difference in embryological, clinical, and neonatal outcomes between the SERC (+) and SERC (–) cycles. The fertilization rate (73.9%), good quality blastocyst rate (26.7%) and the speed of blastocyst development (44.4%) were significantly lower (P < 0.05) in SERC (+) oocytes than in unaffected counterparts (86.2%, 44.1% and 63.4%, respectively). Furthermore, the proportion of blastocysts with trophectoderm (TE) grade C was significantly higher in the SERC (+) oocyte group than in the SERC (–) oocyte group (73.3 vs. 55.9%, P < 0.05). After adjusting for age, years of infertility, endometriosis, stimulation protocols (GnRHa), and male infertility, multiple logistic regression analysis revealed that the presence of SERCs in the oocytes significantly affected the speed of blastocyst development (odds ratio, 2.812; 95% CI, 1.257–6.292; P = 0.012). These findings suggest that the presence of SERCs in oocytes may negatively affect blastocyst quality and the speed of blastocyst development.

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