scholarly journals Developmental Changes in the Distribution of the Endoplasmic Reticulum and Inositol 1,4,5-Trisphosphate Receptors and the Spatial Pattern of Ca2+ Release during Maturation of Hamster Oocytes

1995 ◽  
Vol 170 (2) ◽  
pp. 594-606 ◽  
Author(s):  
Koichi Shiraishi ◽  
Akiko Okada ◽  
Hideki Shirakawa ◽  
Setsuko Nakanishi ◽  
Katsuhiko Mikoshiba ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Spatial Pattern ◽  
Developmental Changes ◽  
Inositol 1,4,5 Trisphosphate

scholarly journals Inositol 1,4,5 trisphosphate releases calcium from specialized sites within Limulus photoreceptors

1987 ◽  
Vol 104 (4) ◽  
pp. 933-937 ◽  
Author(s):  
R Payne ◽  
A Fein
Keyword(s):  
Endoplasmic Reticulum ◽  
Injection Site ◽  
Intracellular Calcium ◽  
Subcellular Distribution ◽  
Smooth Endoplasmic Reticulum ◽  
Image Intensifier ◽  
Photoreceptor Cells ◽  
Calcium Stores ◽  
Inositol 1,4,5 Trisphosphate ◽  
Probable Site

We have investigated the subcellular distribution and identity of inositol trisphosphate (InsP3)-sensitive calcium stores in living Limulus ventral photoreceptor cells, where light and InsP3 are known to raise intracellular calcium. We injected ventral photoreceptor cells with the photoprotein aequorin and viewed its luminescence with an image intensifier. InsP3 only elicited detectable aequorin luminescence when injected into the light-sensitive rhabdomeral (R)-lobe where aequorin luminescence induced by light was also confined. Calcium stores released by light and InsP3 are therefore localized to the R-lobe. Within the R-lobe, InsP3-induced aequorin luminescence was further confined around the injection site, due to rapid dilution and/or degradation of injected InsP3. Prominent cisternae of smooth endoplasmic reticulum are uniquely localized within the cell beneath the microvillar surface of the R-lobe (Calman, B., and S. Chamberlain, 1982, J. Gen. Physiol., 80:839-862). These cisternae are the probable site of InsP3 action.

scholarly journals Bi-allelic variants in RNF170 are associated with hereditary spastic paraplegia

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Matias Wagner ◽  
Daniel P. S. Osborn ◽  
Ina Gehweiler ◽  
Maike Nagel ◽  
Ulrike Ulmer ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hereditary Spastic Paraplegia ◽  
Degradation Pathway ◽  
Therapeutic Interventions ◽  
Spastic Paraplegia ◽  
Ubiquitin E3 Ligase ◽  
Wide Range ◽  
Inositol 1,4,5 Trisphosphate ◽  
Cerebellar Ataxias ◽  
Trisphosphate Receptor

Abstract Alterations of Ca2+ homeostasis have been implicated in a wide range of neurodegenerative diseases. Ca2+ efflux from the endoplasmic reticulum into the cytoplasm is controlled by binding of inositol 1,4,5-trisphosphate to its receptor. Activated inositol 1,4,5-trisphosphate receptors are then rapidly degraded by the endoplasmic reticulum-associated degradation pathway. Mutations in genes encoding the neuronal isoform of the inositol 1,4,5-trisphosphate receptor (ITPR1) and genes involved in inositol 1,4,5-trisphosphate receptor degradation (ERLIN1, ERLIN2) are known to cause hereditary spastic paraplegia (HSP) and cerebellar ataxia. We provide evidence that mutations in the ubiquitin E3 ligase gene RNF170, which targets inositol 1,4,5-trisphosphate receptors for degradation, are the likely cause of autosomal recessive HSP in four unrelated families and functionally evaluate the consequences of mutations in patient fibroblasts, mutant SH-SY5Y cells and by gene knockdown in zebrafish. Our findings highlight inositol 1,4,5-trisphosphate signaling as a candidate key pathway for hereditary spastic paraplegias and cerebellar ataxias and thus prioritize this pathway for therapeutic interventions.

scholarly journals Cytosolic Phosphorylation of Calnexin Controls Intracellular Ca2+ Oscillations via an Interaction with Serca2b

2000 ◽  
Vol 149 (6) ◽  
pp. 1235-1248 ◽  
Author(s):  
H. Llewelyn Roderick ◽  
James D. Lechleiter ◽  
Patricia Camacho
Keyword(s):  
Endoplasmic Reticulum ◽  
Xenopus Oocytes ◽  
Transmembrane Protein ◽  
Calcium Atpase ◽  
Site Directed Mutagenesis ◽  
Serine Residue ◽  
Endoplasmic Reticulum Calcium ◽  
Inositol 1,4,5 Trisphosphate ◽  
Functional Inhibition ◽  
Cytosolic Domain

Calreticulin (CRT) and calnexin (CLNX) are lectin chaperones that participate in protein folding in the endoplasmic reticulum (ER). CRT is a soluble ER lumenal protein, whereas CLNX is a transmembrane protein with a cytosolic domain that contains two consensus motifs for protein kinase (PK) C/proline- directed kinase (PDK) phosphorylation. Using confocal Ca2+ imaging in Xenopus oocytes, we report here that coexpression of CLNX with sarco endoplasmic reticulum calcium ATPase (SERCA) 2b results in inhibition of intracellular Ca2+ oscillations, suggesting a functional inhibition of the pump. By site-directed mutagenesis, we demonstrate that this interaction is regulated by a COOH-terminal serine residue (S562) in CLNX. Furthermore, inositol 1,4,5-trisphosphate– mediated Ca2+ release results in a dephosphorylation of this residue. We also demonstrate by coimmunoprecipitation that CLNX physically interacts with the COOH terminus of SERCA2b and that after dephosphorylation treatment, this interaction is significantly reduced. Together, our results suggest that CRT is uniquely regulated by ER lumenal conditions, whereas CLNX is, in addition, regulated by the phosphorylation status of its cytosolic domain. The S562 residue in CLNX acts as a molecular switch that regulates the interaction of the chaperone with SERCA2b, thereby affecting Ca2+ signaling and controlling Ca2+-sensitive chaperone functions in the ER.

scholarly journals Actions of inositol phosphates on Ca2+ pools in guinea-pig hepatocytes

1984 ◽  
Vol 224 (3) ◽  
pp. 741-746 ◽  
Author(s):  
G M Burgess ◽  
R F Irvine ◽  
M J Berridge ◽  
J S McKinney ◽  
J W Putney
Keyword(s):  
Endoplasmic Reticulum ◽  
Guinea Pig ◽  
Inositol Phosphates ◽  
Second Messenger ◽  
Release Mechanism ◽  
Specific Receptor ◽  
Rapid Release ◽  
Inositol 1,4,5 Trisphosphate

In permeabilized hepatocytes, inositol 1,4,5-trisphosphate, inositol 2,4,5-trisphosphate and inositol 4,5-bisphosphate induced rapid release of Ca2+ from an ATP-dependent, non-mitochondrial vesicular pool, probably endoplasmic reticulum. The order of potency was inositol 1,4,5-trisphosphate greater than inositol 2,4,5-trisphosphate greater than inositol 4,5-bisphosphate. The Ca2+-releasing action of inositol 1,4,5-trisphosphate is not inhibited by high [Ca2+], nor is it dependent on [ATP] in the range of 50 microM-1.5 mM. These results suggest a role for inositol 1,4,5-trisphosphate as a second messenger in hormone-induced Ca2+ mobilisation, and that a specific receptor is involved in the Ca2+-release mechanism.

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