Structural interactions of actin filaments and endoplasmic reticulum in honeybee photoreceptor cells

1992 ◽  
Vol 268 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Otto Baumann
Keyword(s):  
Endoplasmic Reticulum ◽  
Actin Filaments ◽  
Photoreceptor Cells ◽  
Structural Interactions

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 Myosin Motors and Not Actin Comets Are Mediators of the Actin-based Golgi-to-Endoplasmic Reticulum Protein Transport

2003 ◽  
Vol 14 (2) ◽  
pp. 445-459 ◽  
Author(s):  
Juan M. Durán ◽  
Ferran Valderrama ◽  
Susana Castel ◽  
Juana Magdalena ◽  
Mónica Tomás ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Light Chain ◽  
Shiga Toxin ◽  
Actin Filaments ◽  
Protein Transport ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii ◽  
Myosin Motors

We have previously reported that actin filaments are involved in protein transport from the Golgi complex to the endoplasmic reticulum. Herein, we examined whether myosin motors or actin comets mediate this transport. To address this issue we have used, on one hand, a combination of specific inhibitors such as 2,3-butanedione monoxime (BDM) and 1-[5-isoquinoline sulfonyl]-2-methyl piperazine (ML7), which inhibit myosin and the phosphorylation of myosin II by the myosin light chain kinase, respectively; and a mutant of the nonmuscle myosin II regulatory light chain, which cannot be phosphorylated (MRLC2AA). On the other hand, actin comet tails were induced by the overexpression of phosphatidylinositol phosphate 5-kinase. Cells treated with BDM/ML7 or those that express the MRLC2AA mutant revealed a significant reduction in the brefeldin A (BFA)-induced fusion of Golgi enzymes with the endoplasmic reticulum (ER). This delay was not caused by an alteration in the formation of the BFA-induced tubules from the Golgi complex. In addition, the Shiga toxin fragment B transport from the Golgi complex to the ER was also altered. This impairment in the retrograde protein transport was not due to depletion of intracellular calcium stores or to the activation of Rho kinase. Neither the reassembly of the Golgi complex after BFA removal nor VSV-G transport from ER to the Golgi was altered in cells treated with BDM/ML7 or expressing MRLC2AA. Finally, transport carriers containing Shiga toxin did not move into the cytosol at the tips of comet tails of polymerizing actin. Collectively, the results indicate that 1) myosin motors move to transport carriers from the Golgi complex to the ER along actin filaments; 2) nonmuscle myosin II mediates in this process; and 3) actin comets are not involved in retrograde transport.

scholarly journals Receptor-mediated Drp1 oligomerization on endoplasmic reticulum

2017 ◽  
Vol 216 (12) ◽  
pp. 4123-4139 ◽  
Author(s):  
Wei-Ke Ji ◽  
Rajarshi Chakrabarti ◽  
Xintao Fan ◽  
Lori Schoenfeld ◽  
Stefan Strack ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Actin Filaments ◽  
Mammalian Cells ◽  
Actin Polymerization ◽  
Mitochondrial Division ◽  
Multiple Factors ◽  
Guanosine Triphosphatase

Drp1 is a dynamin guanosine triphosphatase important for mitochondrial and peroxisomal division. Drp1 oligomerization and mitochondrial recruitment are regulated by multiple factors, including interaction with mitochondrial receptors such as Mff, MiD49, MiD51, and Fis. In addition, both endoplasmic reticulum (ER) and actin filaments play positive roles in mitochondrial division, but mechanisms for their roles are poorly defined. Here, we find that a population of Drp1 oligomers is associated with ER in mammalian cells and is distinct from mitochondrial or peroxisomal Drp1 populations. Subpopulations of Mff and Fis1, which are tail-anchored proteins, also localize to ER. Drp1 oligomers assemble on ER, from which they can transfer to mitochondria. Suppression of Mff or inhibition of actin polymerization through the formin INF2 significantly reduces all Drp1 oligomer populations (mitochondrial, peroxisomal, and ER bound) and mitochondrial division, whereas Mff targeting to ER has a stimulatory effect on division. Our results suggest that ER can function as a platform for Drp1 oligomerization, and that ER-associated Drp1 contributes to mitochondrial division.

scholarly journals The V-ATPase V1 subunit A1 is required for rhodopsin anterograde trafficking in Drosophila

2018 ◽  
Vol 29 (13) ◽  
pp. 1640-1651 ◽  
Author(s):  
Haifang Zhao ◽  
Jing Wang ◽  
Tao Wang
Keyword(s):  
Animal Model ◽  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Photoreceptor Cell ◽  
Photoreceptor Cells ◽  
Secretory Vesicle ◽  
Light Sensitivity ◽  
Model System ◽  
Genetic Screen ◽  
Reduced Light

Synthesis and maturation of the light sensor, rhodopsin, are critical for the maintenance of light sensitivity and for photoreceptor homeostasis. In Drosophila, the main rhodopsin, Rh1, is synthesized in the endoplasmic reticulum and transported to the rhabdomere through the secretory pathway. In an unbiased genetic screen for factors involved in rhodopsin homeostasis, we identified mutations in vha68-1, which encodes the vacuolar proton-translocating ATPase (V-ATPase) catalytic subunit A isoform 1 of the V1 component. Loss of vha68-1 in photoreceptor cells disrupted post-Golgi anterograde trafficking of Rh1, reduced light sensitivity, increased secretory vesicle pH, and resulted in incomplete Rh1 deglycosylation. In addition, vha68-1 was required for activity-independent photoreceptor cell survival. Importantly, vha68-1 mutants exhibited phenotypes similar to those exhibited by mutations in the V0 component of V-ATPase, vha100-1. These data demonstrate that the V1 and V0 components of V-ATPase play key roles in post-Golgi trafficking of Rh1 and that Drosophila may represent an important animal model system for studying diseases associated with V-ATPase dysfunction.

Analysis of mitochondria, endoplasmic reticulum and actin filaments after PDT with AlPcS 4

2004 ◽  
Vol 18 (4) ◽  
pp. 207-212 ◽  
Author(s):  
A. C. Tedesco ◽  
G. Sousa ◽  
R. A. Z�ngaro ◽  
N. S. Silva ◽  
M. T. T. Pacheco ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Actin Filaments

Particles Seen in Fefeze-Fracture Preparattoks

1969 ◽  
Vol 27 ◽  
pp. 206-207
Author(s):  
Stanley Bullivant
Keyword(s):  
Endoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Nuclear Membrane ◽  
Actin Filaments ◽  
Carbon Coating ◽  
Freeze Fracture ◽  
Animal Tissues ◽  
Outer Nuclear Membrane ◽  
First Category ◽  
Electron Microscopical

A variety of animal tissues were examined by the simple freeze-fracture technique. An apparatus was used in which the Pt shadowing and carbon coating was carried out through aligned tunnels or apertures. Tn this way the previously fractured cold specimen is protected from contamination.Some particles seen in freeze-fracture replicas can be correlated with structures seen by other electron microscopical techniques. Into this first category fall the broken-off ends of myosin and actin filaments, (Figure 1), the broken-off ends of nucleohistone fibrils the particles seen between membranes in the close junction in cardiac muscle (Figure 2) and quantasomes in chloroplasts. The second group of particles are those found on membranes. An example of these is provided by the membrane faces seen in a fracture through the endoplasmic reticulum (Figure 3). The topology of the situation can be worked out using the outer nuclear membrane as a reference and counting off alternate cytoplasmic and cisternal spaces.

Gelsolin — evidence for a role in turnover of junction-related actin filaments in Sertoli cells

2002 ◽  
Vol 115 (3) ◽  
pp. 499-505 ◽  
Author(s):  
Julian A. Guttman ◽  
Paul Janmey ◽  
A. Wayne Vogl
Keyword(s):  
Endoplasmic Reticulum ◽  
Phospholipase C ◽  
Sertoli Cells ◽  
Actin Filaments ◽  
Synthetic Peptide ◽  
Inositol Triphosphate ◽  
Binding Region ◽  
Phosphoinositide Pathway ◽  
Hydrolysis Of ◽  
Adhesion Complex

The gelsolin-phosphoinositide pathway may be part of the normal mechanism by which Sertoli cells regulate sperm release and turnover of the blood-testis barrier. The intercellular adhesion complexes (ectoplasmic specializations)involved with these two processes are tripartite structures consisting of the plasma membrane, a layer of actin filaments and a cistern of endoplasmic reticulum. Gelsolin is concentrated in these adhesion complexes. In addition,phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and phosphoinositide-specific phospholipase C are found in the structures. Treatment of isolated spermatid/junction complexes with exogenous phosphoinositide-specific phospholipase C, or with a synthetic peptide consisting of the PtdIns(4,5)P2 binding region of gelsolin, results in the release of gelsolin and loss of actin from the adhesion complexes. We present a model for the disassembly of the actin layer of the adhesion complex that involves the hydrolysis of PtdIns(4,5)P2 resulting in the release of gelsolin within the plaque. Further, we speculate that the hydrolysis of PtdIns(4,5)P2 may result in a local Ca2+ surge via the action of inositol triphosphate on junctional endoplasmic reticulum. This Ca2+ surge would facilitate the actin severing function of gelsolin within the adhesion complex.

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