scholarly journals Dendritic actin delivery service

2018 ◽  
Vol 217 (10) ◽  
pp. 3325-3326
Author(s):  
Yun-Jin Pai ◽  
Adrian W. Moore
Keyword(s):  
Actin Cytoskeleton ◽  
Delivery Service ◽  
Cell Biol ◽  
Dendritic Branching ◽  
Branch Formation

The mechanisms by which the actin cytoskeleton regulates dendritic branching are not fully understood. Nithianandam and Chien (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201711136) discover actin blobs, new structures that mediate dynamic actin delivery within a growing dendrite arbor and that mark sites of future branch formation.

The actin cytoskeleton is required to elaborate and maintain spatial patterning during trichome cell morphogenesis in Arabidopsis thaliana

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5559-5568 ◽  
Author(s):  
J. Mathur ◽  
P. Spielhofer ◽  
B. Kost ◽  
N. Chua
Keyword(s):  
Arabidopsis Thaliana ◽  
Actin Cytoskeleton ◽  
Spatial Patterning ◽  
Actin Microfilaments ◽  
Cell Morphogenesis ◽  
Actin Organization ◽  
Cytoskeleton Organization ◽  
Branch Formation ◽  
Actin Cytoskeleton Organization ◽  
Trichome Cell

Arabidopsis thaliana trichomes provide an attractive model system to dissect molecular processes involved in the generation of shape and form in single cell morphogenesis in plants. We have used transgenic Arabidopsis plants carrying a GFP-talin chimeric gene to analyze the role of the actin cytoskeleton in trichome cell morphogenesis. We found that during trichome cell development the actin microfilaments assumed an increasing degree of complexity from fine filaments to thick, longitudinally stretched cables. Disruption of the F-actin cytoskeleton by actin antagonists produced distorted but branched trichomes which phenocopied trichomes of mutants belonging to the ‘distorted’ class. Subsequent analysis of the actin cytoskeleton in trichomes of the distorted mutants, alien, crooked, distorted1, gnarled, klunker and wurm uncovered actin organization defects in each case. Treatments of wild-type seedlings with microtubule-interacting drugs elicited a radically different trichome phenotype characterized by isotropic growth and a severe inhibition of branch formation; these trichomes did not show defects in actin cytoskeleton organization. A normal actin cytoskeleton was also observed in trichomes of the zwichel mutant which have reduced branching. ZWICHEL, which was previously shown to encode a kinesin-like protein is thought to be involved in microtubule-linked processes. Based on our results we propose that microtubules establish the spatial patterning of trichome branches whilst actin microfilaments elaborate and maintain the overall trichome pattern during development.

Dendrite Elongation and Dendritic Branching Are Affected Separately by Different Forms of Intrinsic Motoneuron Excitability

2008 ◽  
Vol 100 (5) ◽  
pp. 2525-2536 ◽  
Author(s):  
Carsten Duch ◽  
Fernando Vonhoff ◽  
Stefanie Ryglewski
Keyword(s):  
Potassium Channel ◽  
Genetic Model ◽  
Neurological Diseases ◽  
Dendritic Structure ◽  
Dominant Negative ◽  
Intrinsic Excitability ◽  
Dendritic Branch ◽  
Dendritic Branching ◽  
Branch Formation

Dendrites are the fundamental determinant of neuronal wiring. Consequently dendritic defects are associated with numerous neurological diseases and mental retardation. Neuronal activity can have profound effects on dendritic structure, but the mechanisms controlling distinct aspects of dendritic architecture are not fully understood. We use the Drosophila genetic model system to test the effects of altered intrinsic excitability on postembryonic dendritic architecture development. Targeted dominant negative knock-downs of potassium channel subunits allow for selectively increasing the intrinsic excitability of a selected subset of motoneurons, whereas targeted expression of a genetically modified noninactivating potassium channel decrease intrinsic excitability in vivo. Both manipulations cause significant dendritic overgrowth, but by different mechanisms. Increased excitability causes increased dendritic branch formation, whereas decreased excitability causes increased dendritic branch elongation. Therefore dendritic branching and branch elongation are controlled by separate mechanisms that can be addressed selectively in vivo by different manipulations of neuronal intrinsic excitability.

scholarly journals Recent advances in branching mechanisms underlying neuronal morphogenesis

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1779 ◽  
Author(s):  
Shalini Menon ◽  
Stephanie Gupton
Keyword(s):  
Intracellular Signaling ◽  
Synapse Formation ◽  
Neuronal Morphogenesis ◽  
Effector Cells ◽  
Signaling Mechanisms ◽  
Recent Advances ◽  
Dendritic Branching ◽  
Branch Formation ◽  
Cytoskeletal Dynamics ◽  
To Receive

Proper neuronal wiring is central to all bodily functions, sensory perception, cognition, memory, and learning. Establishment of a functional neuronal circuit is a highly regulated and dynamic process involving axonal and dendritic branching and navigation toward appropriate targets and connection partners. This intricate circuitry includes axo-dendritic synapse formation, synaptic connections formed with effector cells, and extensive dendritic arborization that function to receive and transmit mechanical and chemical sensory inputs. Such complexity is primarily achieved by extensive axonal and dendritic branch formation and pruning. Fundamental to neuronal branching are cytoskeletal dynamics and plasma membrane expansion, both of which are regulated via numerous extracellular and intracellular signaling mechanisms and molecules. This review focuses on recent advances in understanding the biology of neuronal branching.

scholarly journals Rotating for elongation: Fat2 whips for the race

2016 ◽  
Vol 212 (5) ◽  
pp. 487-489 ◽  
Author(s):  
Tomke Stürner ◽  
Gaia Tavosanis
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Cell Shape ◽  
Collective Cell Migration ◽  
Cell Biol ◽  
Regulatory Complex ◽  
And Migration ◽  
Cadherin Superfamily

Dynamic rearrangements of the actin cytoskeleton are crucial for cell shape and migration. In this issue, Squarr et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201508081) show that the cadherin superfamily protein Fat2 regulates actin-rich protrusions driving collective cell migration during Drosophila melanogaster egg morphogenesis through its interaction with the WAVE regulatory complex.

scholarly journals Regulating polarity by directing traffic: Cdc42 prevents adherens junctions from Crumblin' aPart

2008 ◽  
Vol 183 (6) ◽  
pp. 971-974 ◽  
Author(s):  
Mara C. Duncan ◽  
Mark Peifer
Keyword(s):  
Cell Adhesion ◽  
Actin Cytoskeleton ◽  
Cell Polarity ◽  
Adherens Junctions ◽  
Vesicular Trafficking ◽  
Cell Junction ◽  
Par Proteins ◽  
Cell Biol ◽  
Embryonic Morphogenesis ◽  
Junction Proteins

The GTPase Cdc42 was among the original genes identified with roles in cell polarity, and interest in its cellular roles from yeast to humans remains high. Cdc42 is a well-known regulator of the actin cytoskeleton, but also plays important roles in vesicular trafficking. In this issue, Harris and Tepass (Harris, K.P, and U. Tepass. 2008. J. Cell. Biol. 183:1129–1143) provide new insights into how Cdc42 and Par proteins work together to modulate cell adhesion and polarity during embryonic morphogenesis by regulating the traffic of key cell junction proteins.

scholarly journals Iqg1p, a Yeast Homologue of the Mammalian IQGAPs, Mediates Cdc42p Effects on the Actin Cytoskeleton

1998 ◽  
Vol 142 (2) ◽  
pp. 443-455 ◽  
Author(s):  
Mahasin A. Osman ◽  
Richard A. Cerione
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Shape ◽  
Temperature Sensitive ◽  
Cellular Functions ◽  
Multinucleated Cells ◽  
Cell Biol ◽  
Pheromone Signaling ◽  
Regulatory Effects ◽  
Mutant Cells ◽  
Two Hybrid

The Rho-type GTPase Cdc42p has been implicated in diverse cellular functions including cell shape, cell motility, and cytokinesis, all of which involve the reorganization of the actin cytoskeleton. Targets of Cdc42p that interface the actin cytoskeleton are likely candidates for mediating cellular activities. In this report, we identify and characterize a yeast homologue for the mammalian IQGAP, a cytoskeletal target for Cdc42p. The yeast IQGAP homologue, designated Iqg1p, displays a two-hybrid interaction with activated Cdc42p and coimmunoprecipitates with actin filaments. Deletion of IQG1 results in a temperature-sensitive lethality and causes aberrant morphologies including elongated and round multinucleated cells. This together with its localization at the mother–bud neck, suggest that Iqg1p promotes budding and cytokinesis. At restrictive temperatures, the vacuoles of the mutant cells enlarge and vesicles accumulate in the bud. Interestingly, Iqg1p shows two-hybrid interactions with the ankyrin repeat–containing protein, Akr1p (Kao, L.-R., J. Peterson, J. Ruiru, L. Bender, and A. Bender. 1996. Mol. Cell. Biol. 16:168–178), which inhibits pheromone signaling and appears to promote cytokinesis and/or trafficking. We also show two-hybrid interactions between Iqg1p and Afr1p, a septin-binding protein involved in projection formation (Konopka, J.B., C. DeMattei, and C. Davis. 1995. Mol. Cell. Biol. 15:723–730). We propose that Iqg1p acts as a scaffold to recruit and localize a protein complex involved in actin-based cellular functions and thus mediates the regulatory effects of Cdc42p on the actin cytoskeleton.

scholarly journals Mutations altering the mitochondrial-cytoplasmic distribution of Mod5p implicate the actin cytoskeleton and mRNA 3' ends and/or protein synthesis in mitochondrial delivery.

1995 ◽  
Vol 15 (12) ◽  
pp. 6884-6894 ◽  
Author(s):  
T Zoladek ◽  
G Vaduva ◽  
L A Hunter ◽  
M Boguta ◽  
B D Go ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Actin Cytoskeleton ◽  
Selection Strategy ◽  
Cell Fractionation ◽  
Gene Products ◽  
Protein Distribution ◽  
Cytoskeleton Organization ◽  
Molecular Approaches ◽  
Apply Genetic ◽  
Cell Biol

The Saccharomyces cerevisiae MOD5 gene encodes proteins that function in three subcellular locations: mitochondria, the cytoplasm, and nuclei (M. Boguta, L.A. Hunter, W.-C. Shen, E. C. Gillman, N. C. Martin, and A. K. Hopper, Mol. Cell. Biol. 14:2298-2306, 1994; E. C. Gillman, L. B. Slusher, N. C. Martin, and A. K. Hopper, Mol. Cell. Biol. 11:2382-2390, 1991). A mutant allele of MOD5 encoding a protein (Mod5p-I,KR6) located predominantly in mitochondria was constructed. Mutants defective in delivering Mod5p-I,KR6 to mitochondria were sought by selecting cells with increased cytosolic activity of this protein. Twenty-five mutants defining four complementation groups, mdp1, mdp2, mdp3, and mdp4, were found. They are unable to respire at 34 degrees C or to grow on glucose medium at 38 degrees C. Cell fractionation studies showed that mdp1, mdp2, and mdp3 mutants have an altered mitochondrial-cytoplasmic distribution of Mod5p. mdp2 can be suppressed by ACT1, the actin-encoding gene. The actin cytoskeleton organization is also aberrant in mdp2 cells. MDP2 is the same as VRP1 (S. F. H. Donnelly, M. J. Picklington, D. Pallotta, and E. Orr, Mol. Microbiol. 10:585-596, 1993). MDP3 is identical to PAN1, which encodes a protein that interacts with mRNA 3' ends and affects initiation of protein synthesis (A. B. Sachs and J. A. Deardoff, Cell 70:961-973, 1992). These results implicate the actin cytoskeleton and mRNA 3' ends and/or protein synthesis as being as important for protein distribution in S. cerevisiae as they are for distribution of cytosolic proteins in higher eukaryotes. This provides the potential to apply genetic and molecular approaches to study gene products and mechanisms involved in this type of protein distribution. The selection strategy also offers a new approach for identifying gene products involved in the distribution of proteins to their subscellular destinations.

scholarly journals Fission Yeast Aip3p (spAip3p) Is Required for an Alternative Actin-directed Polarity Program

2001 ◽  
Vol 12 (5) ◽  
pp. 1275-1291 ◽  
Author(s):  
Hui Jin ◽  
David C. Amberg
Keyword(s):  
Actin Cytoskeleton ◽  
Fission Yeast ◽  
Cell Polarity ◽  
Secretory Pathway ◽  
Budding Yeast ◽  
Microtubule Cytoskeleton ◽  
Interacting Protein ◽  
Sequencing Project ◽  
Polarized Cell Growth ◽  
Branch Formation

Aip3p is an actin-interacting protein that regulates cell polarity in budding yeast. The Schizosaccharomyces pombe-sequencing project recently led to the identification of a homologue of Aip3p that we have named spAip3p. Our results confirm that spAip3p is a true functional homologue of Aip3p. When expressed in budding yeast, spAip3p localizes similarly to Aip3p during the cell cycle and complements the cell polarity defects of anaip3Δ strain. Two-hybrid analysis shows that spAip3p interacts with actin similarly to Aip3p. In fission yeast, spAip3p localizes to both cell ends during interphase and later organizes into two rings at the site of cytokinesis. spAip3p localization to cell ends is dependent on microtubule cytoskeleton, its localization to the cell middle is dependent on actin cytoskeleton, and both patterns of localization require an operative secretory pathway. Overexpression of spAip3p disrupts the actin cytoskeleton and cell polarity, leading to morphologically aberrant cells. Fission yeast, which normally rely on the microtubule cytoskeleton to establish their polarity axis, can use the actin cytoskeleton in the absence of microtubule function to establish a new polarity axis, leading to the formation of branched cells. spAip3p localizes to, and is required for, branch formation, confirming its role in actin-directed polarized cell growth in bothSchizosaccharomyces pombe and Saccharomyces cerevisiae.

scholarly journals Opposing Roles for Actin in Cdc42p Polarization

2005 ◽  
Vol 16 (3) ◽  
pp. 1296-1304 ◽  
Author(s):  
Javier E. Irazoqui ◽  
Audrey S. Howell ◽  
Chandra L. Theesfeld ◽  
Daniel J. Lew
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Polarity ◽  
Budding Yeast ◽  
Cortical Actin ◽  
Independent Manner ◽  
Actin Depolymerization ◽  
Cell Biol ◽  
Actin Cables ◽  
Unexpected Difference

In animal and fungal cells, the monomeric GTPase Cdc42p is a key regulator of cell polarity that itself exhibits a polarized distribution in asymmetric cells. Previous work showed that in budding yeast, Cdc42p polarization is unaffected by depolymerization of the actin cytoskeleton (Ayscough et al., J. Cell Biol. 137, 399–416, 1997). Surprisingly, we now report that unlike complete actin depolymerization, partial actin depolymerization leads to the dispersal of Cdc42p from the polarization site in unbudded cells. We provide evidence that dispersal is due to endocytosis associated with cortical actin patches and that actin cables are required to counteract the dispersal and maintain Cdc42p polarity. Thus, although Cdc42p is initially polarized in an actin-independent manner, maintaining that polarity may involve a reinforcing feedback between Cdc42p and polarized actin cables to counteract the dispersing effects of actin-dependent endocytosis. In addition, we report that once a bud has formed, polarized Cdc42p becomes more resistant to dispersal, revealing an unexpected difference between unbudded and budded cells in the organization of the polarization site.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

Sign in / Sign up

Export Citation Format

Share Document