scholarly journals A role of OCRL in clathrin-coated pit dynamics and uncoating revealed by studies of Lowe syndrome cells

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Ramiro Nández ◽  
Daniel M Balkin ◽  
Mirko Messa ◽  
Liang Liang ◽  
Summer Paradise ◽  
...  
Keyword(s):  
Late Stage ◽  
Actin Polymerization ◽  
Clinical Manifestations ◽  
Coated Vesicles ◽  
Lowe Syndrome ◽  
Syndrome Patient ◽  
Coated Pits ◽  
Intracellular Sorting ◽  
Endocytic Vesicles

Mutations in the inositol 5-phosphatase OCRL cause Lowe syndrome and Dent's disease. Although OCRL, a direct clathrin interactor, is recruited to late-stage clathrin-coated pits, clinical manifestations have been primarily attributed to intracellular sorting defects. Here we show that OCRL loss in Lowe syndrome patient fibroblasts impacts clathrin-mediated endocytosis and results in an endocytic defect. These cells exhibit an accumulation of clathrin-coated vesicles and an increase in U-shaped clathrin-coated pits, which may result from sequestration of coat components on uncoated vesicles. Endocytic vesicles that fail to lose their coat nucleate the majority of the numerous actin comets present in patient cells. SNX9, an adaptor that couples late-stage endocytic coated pits to actin polymerization and which we found to bind OCRL directly, remains associated with such vesicles. These results indicate that OCRL acts as an uncoating factor and that defects in clathrin-mediated endocytosis likely contribute to pathology in patients with OCRL mutations.

scholarly journals The Role of Dynamin and Its Binding Partners in Coated Pit Invagination and Scission

2001 ◽  
Vol 152 (2) ◽  
pp. 309-324 ◽  
Author(s):  
Elaine Hill ◽  
Jeroen van der Kaay ◽  
C. Peter Downes ◽  
Elizabeth Smythe
Keyword(s):  
Plasma Membrane ◽  
Sh3 Domain ◽  
Coated Vesicles ◽  
Coated Vesicle ◽  
Vesicle Formation ◽  
Coated Pits ◽  
Binding Partners ◽  
Late Stages

Plasma membrane clathrin-coated vesicles form after the directed assembly of clathrin and the adaptor complex, AP2, from the cytosol onto the membrane. In addition to these structural components, several other proteins have been implicated in clathrin-coated vesicle formation. These include the large molecular weight GTPase, dynamin, and several Src homology 3 (SH3) domain–containing proteins which bind to dynamin via interactions with its COOH-terminal proline/arginine-rich domain (PRD). To understand the mechanism of coated vesicle formation, it is essential to determine the hierarchy by which individual components are targeted to and act in coated pit assembly, invagination, and scission. To address the role of dynamin and its binding partners in the early stages of endocytosis, we have used well-established in vitro assays for the late stages of coated pit invagination and coated vesicle scission. Dynamin has previously been shown to have a role in scission of coated vesicles. We show that dynamin is also required for the late stages of invagination of clathrin-coated pits. Furthermore, dynamin must bind and hydrolyze GTP for its role in sequestering ligand into deeply invaginated coated pits. We also demonstrate that the SH3 domain of endophilin, which binds both synaptojanin and dynamin, inhibits both late stages of invagination and also scission in vitro. This inhibition results from a reduction in phosphoinositide 4,5-bisphosphate levels which causes dissociation of AP2, clathrin, and dynamin from the plasma membrane. The dramatic effects of the SH3 domain of endophilin led us to propose a model for the temporal order of addition of endophilin and its binding partner synaptojanin in the coated vesicle cycle.

scholarly journals Endocytic vesicles and surface invaginations in cultured vascular endothelium: a morphometric comparison.

1981 ◽  
Vol 29 (12) ◽  
pp. 1437-1441 ◽  
Author(s):  
P F Davies ◽  
L Kuczera
Keyword(s):  
Cell Surface ◽  
Vascular Endothelium ◽  
Ruthenium Red ◽  
Coated Vesicles ◽  
Membrane Glycoproteins ◽  
Coated Pits ◽  
Ruthenium Red Staining ◽  
Almost All ◽  
Endocytic Vesicles

Ruthenium red staining of plasma membrane glycoproteins of confluent cultured arterial endothelial cells revealed that the limiting membrane of many apparently discrete cytoplasmic vesicles was continuous with the plasmalemma. Surface invaginations accessible to ruthenium red appeared as vesicles when sectioned out of the plane of attachment to the cell surface, Morphometric analysis of ruthenium red-positive (RR+) and ruthenium red-negative vesicles (RR-) indicated that 47.2% of the total apparent vesicle population was RR+ and that those infoldings accounted for 19.6 +/- 1.4% of the cell surface in transverse sections. Whereas 14.9% of the true vesicles (ruthenium red-negative) were coated vesicles, only 1.1% of RR+ "vesicles" were coated pits. These studies show that although many deep infoldings of the cell surface may be misinterpreted as vesicles, almost all are uncoated. The existence of discrete coated vesicles (independent of coated pits) in vascular endothelium in vitro is readily apparent.

The role of the Lowe syndrome protein OCRL in the endocytic pathway

2015 ◽  
Vol 396 (12) ◽  
pp. 1293-1300 ◽  
Author(s):  
Shruti Sharma ◽  
Agnieszka Skowronek ◽  
Kai Sven Erdmann
Keyword(s):  
Genetic Disorders ◽  
Endocytic Pathway ◽  
Lowe Syndrome ◽  
Coated Pits ◽  
Golgi Network ◽  
Endocytic Compartments ◽  
Syndrome Protein

Abstract Mutations of the inositol-5-phosphatase OCRL cause Lowe syndrome and Dent-II disease. Both are rare genetic disorders characterized by renal defects. Lowe syndrome is furthermore characterized by defects of the eye (congenital cataracts) and nervous system (mental disabilities, hypotonia). OCRL has been localised to various endocytic compartments suggesting impairments in the endocytic pathway as possible disease mechanism. Recent evidence strongly supports this view and shows essential roles of OCRL at clathrin coated pits, transport of cargo from endosomes to the trans-Golgi network as well as recycling of receptors from endosomes to the plasma membrane. In particular in vitro and in vivo evidence demonstrates an important role of OCRL in recycling of megalin, a multi-ligand receptor crucial for reabsorption of nutrients in the proximal tubulus, a process severely impaired in Lowe syndrome patients. Thus defects in the endocytic pathway are likely to significantly contribute to the kidney phenotype in Lowe syndrome and Dent-II disease.

scholarly journals Filipin-cholesterol complexes form in uncoated vesicle membrane derived from coated vesicles during receptor-mediated endocytosis of low density lipoprotein.

1983 ◽  
Vol 96 (5) ◽  
pp. 1273-1278 ◽  
Author(s):  
D J McGookey ◽  
K Fagerberg ◽  
R G Anderson
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Coated Vesicles ◽  
Low Density ◽  
Vesicle Membrane ◽  
Electron Microscopic ◽  
Coated Pits ◽  
Receptor Mediated Endocytosis ◽  
Transport Vesicles ◽  
Endocytic Vesicles

Filipin has been widely used as an electron microscopic probe to detect 3-beta-hydroxysterols, principally cholesterol, in cellular membranes. When it complexes with sterol, it forms globular deposits that disrupt the planar organization of the membrane. Previous studies have shown that coated pits and coated vesicles, specialized membranes involved in receptor-mediated endocytosis, do not appear to bind filipin. This has led to the suggestion that these membranes are low in cholesterol compared with the remainder of the plasma membrane. Since coated endocytic vesicles become uncoated vesicles during the transport of internalized ligands to the lysosome, we have carried out studies to determine whether or not the membranes that surround these transport vesicles are unable to bind filipin and therefore, are also low in cholesterol. Cells were incubated with ferritin-conjugated ligands that bind to low density lipoprotein (LDL) receptors in coated pits. After allowing internalization of the conjugates, we fixed the cells in either the presence or absence of filipin. This permitted us to identify all of the vesicles involved in the transport of LDL to the lysosome and to determine whether the membranes of these vesicles were able to bind filipin. We found that, coordinate with the dissociation of the clathrin coat from the endocytic vesicles, the membranes became sensitive to the formation of filipin-sterol complexes. Furthermore, all of the uncoated endocytic vesicle membranes, as well as the lysosomal membranes, bound filipin. This suggests either that coated membrane contains normal cholesterol levels, which is not easily detected with filipin, or that cholesterol rapidly moves into endocytic vesicles after the clathrin coat dissociates from the membrane.

scholarly journals Molecules internalized by clathrin-independent endocytosis are delivered to endosomes containing transferrin receptors.

1993 ◽  
Vol 123 (1) ◽  
pp. 89-97 ◽  
Author(s):  
S H Hansen ◽  
K Sandvig ◽  
B van Deurs
Keyword(s):  
High Efficiency ◽  
De Novo ◽  
Coated Vesicles ◽  
Transferrin Receptors ◽  
Con A ◽  
Coated Pits ◽  
Late Endosomes ◽  
Endocytic Vesicles ◽  
Endocytic Compartments ◽  
K Depletion

We have previously demonstrated that the preendosomal compartment in addition to clathrin-coated vesicles, comprises distinct nonclathrin coated endocytic vesicles mediating clathrin-independent endocytosis (Hansen, S. H., K. Sandvig, and B. van Deurs. 1991. J. Cell Biol. 113:731-741). Using K+ depletion in HEp-2 cells to block clathrin-dependent but not clathrin-independent endocytosis, we have now traced the intracellular routing of these nonclathrin coated vesicles to see whether molecules internalized by clathrin-independent endocytosis are delivered to a unique compartment or whether they reach the same early and late endosomes as encountered by molecules internalized with high efficiency through clathrin-coated pits and vesicles. We find that Con A-gold internalized by clathrin-independent endocytosis is delivered to endosomes containing transferrin receptors. After incubation of K(+)-depleted cells with Con A-gold for 15 min, approximately 75% of Con A-gold in endosomes is colocalized with transferrin receptors. Endosomes containing only Con A-gold may be accounted for either by depletion of existing endosomes for transferrin receptors or by de novo generation of endosomes. Cationized gold and BSA-gold internalized in K(+)-depleted cells are also delivered to endosomes containing transferrin receptors. h-lamp-1-enriched compartments are only reached occasionally within 30 min in K(+)-depleted as well as in control cells. Thus, preendosomal vesicles generated by clathrin-independent endocytosis do not fuse to any marked degree with late endocytic compartments. These data show that in HEp-2 cells, molecules endocytosed without clathrin are delivered to the same endosomes as reached by transferrin receptors internalized through clathrin-coated pits.

scholarly journals Receptor-mediated endocytosis of insulin: role of microvilli, coated pits, and coated vesicles.

1982 ◽  
Vol 79 (24) ◽  
pp. 7788-7791 ◽  
Author(s):  
J. Y. Fan ◽  
J. L. Carpentier ◽  
P. Gorden ◽  
E. Van Obberghen ◽  
N. M. Blackett ◽  
...  
Keyword(s):  
Coated Vesicles ◽  
Coated Pits ◽  
Receptor Mediated Endocytosis

Modern methods of treating rosacea

2019 ◽  
Vol 1 (7) ◽  
pp. 65-71
Author(s):  
O. A. Egorova ◽  
K. A. Novikov
Keyword(s):  
Clinical Manifestations ◽  
Treatment Method ◽  
Current Data ◽  
Trigger Factors ◽  
Laser Technology ◽  
Individual Approach ◽  
Modern Methods ◽  
Methods Of Treatment ◽  
Choice Of Therapy

Presented current data on the etiology of rosacea, the main aspects of pathogenesis, clinical forms of the disease. Reflects trigger factors leading to rosacea, as well as complicating its course. Modern methods of treatment are described, including the use of new safe preparations of ivermectin and brimonidine, providing a good, lasting effect of clinical manifestations of rosacea. The role of laser technology, actively occupying a leading place in the choice of physiotherapeutic treatment method, is noted. The need for an individual approach in the choice of therapy for each patient with rosacea is emphasized.

Papillon-Lefevre Syndrome: Challenge for Periodontal Management

2019 ◽  
Vol 3 (2) ◽  
pp. 84-86
Author(s):  
Krishna Prasad Lamichhane ◽  
Shaili Pradhan ◽  
Ranjita Shreshta Gorkhali ◽  
Pramod Kumar Koirala
Keyword(s):  
Significant Role ◽  
Autosomal Recessive ◽  
Clinical Manifestations ◽  
Autosomal Recessive Disorder ◽  
Genetic Mutations ◽  
Rare Autosomal Recessive Disorder ◽  
Diagnosis And Management ◽  
Periodontal Destruction ◽  
Palmoplantar Keratosis

Papillon-Lefèvre syndrome (PLS) is a rare autosomal recessive disorder associated with rapidly progressing periodontitis leading to premature loss of deciduous and permanent dentition and diffuse palmoplantar keratosis. Immunologic alterations, genetic mutations, and role of bacteria are some aetiologic factors. Patients present with early periodontal destruction, so periodontists play a significant role in diagnosis and management. This paper reports a case of Papillon- Lefevre syndrome with its clinical manifestations and challenges for periodontal management which was diagnosed in dental department.

Disseminated intravascular coagulation syndrome

2020 ◽  
pp. 22-40
Author(s):  
A. Kulikov
Keyword(s):  
Clinical Practice ◽  
Disseminated Intravascular Coagulation ◽  
Blood Cells ◽  
Physical State ◽  
Clinical Manifestations ◽  
Vascular Wall ◽  
Stages Of Development ◽  
Intravascular Coagulation ◽  
Hemostatic Disorder

Presented material reveals main links in the pathogenesis of hemostatic disorder. In particular, attention is paid to the role of the lungs, liver and other organs in the development of this process. Role of vascular wall and blood cells in regulation of the physical state of blood is described in detail. The most frequent factors leading to hypercoagulation are indicated. Difference between hypercoagulation and thrombophilia is shown. The latter is found in clinical practice quite often, but at the same time, it is poorly diagnosed. Such a terrible complication of hemostatic disorder as disseminated intravascular coagulation is described. Its classification, stages of development, clinical manifestations are offered to the readers.

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