scholarly journals CRMP4 and CRMP2 Interact to Coordinate Cytoskeleton Dynamics, Regulating Growth Cone Development and Axon Elongation

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Minghui Tan ◽  
Caihui Cha ◽  
Yongheng Ye ◽  
Jifeng Zhang ◽  
Sumei Li ◽  
...  
Keyword(s):  
Growth Cone ◽  
Promoting Effect ◽  
Interaction Domain ◽  
Axonal Elongation ◽  
Axon Elongation ◽  
Cellular Processes ◽  
Cytoskeletal Dynamics ◽  
Cone Development ◽  
Cytoskeleton Dynamics

Cytoskeleton dynamics are critical phenomena that underpin many fundamental cellular processes. Collapsin response mediator proteins (CRMPs) are highly expressed in the developing nervous system, mediating growth cone guidance, neuronal polarity, and axonal elongation. However, whether and how CRMPs associate with microtubules and actin coordinated cytoskeletal dynamics remain unknown. In this study, we demonstrated that CRMP2 and CRMP4 interacted with tubulin and actinin vitroand colocalized with the cytoskeleton in the transition-zone in developing growth cones. CRMP2 and CRMP4 also interacted with one another coordinately to promote growth cone development and axonal elongation. Genetic silencing of CRMP2 enhanced, whereas overexpression of CRMP2 suppressed, the inhibitory effects of CRMP4 knockdown on axonal development. In addition, knockdown of CRMP2 or overexpression of truncated CRMP2 reversed the promoting effect of CRMP4. With the overexpression of truncated CRMP2 or CRMP4 lacking the cytoskeleton interaction domain, the promoting effect of CRMP was suppressed. These data suggest a model in which CRMP2 and CRMP4 form complexes to bridge microtubules and actin and thus work cooperatively to regulate growth cone development and axonal elongation.

scholarly journals Nestin in immature embryonic neurons regulates axon growth cone morphology and Semaphorin3a sensitivity

2017 ◽  
Author(s):  
C.J. Bott ◽  
C. G. Johnson ◽  
C.C. Yap ◽  
N.D. Dwyer ◽  
K.A. Litwa ◽  
...  
Keyword(s):  
Growth Cone ◽  
Intermediate Filament ◽  
Cortical Neurons ◽  
Axon Growth ◽  
Neural Progenitors ◽  
Nestin Expression ◽  
Guidance Cue ◽  
Cytoskeletal Dynamics ◽  
Newborn Neurons

AbstractCorrect wiring in the neocortex requires that responses to an individual guidance cue vary among neurons in the same location, and within the same neuron over time. Nestin is an atypical intermediate filament expressed highly in neural progenitors and is thus used widely as a progenitor marker. Here we show a subpopulation of embryonic cortical neurons which transiently express nestin in their axons. Nestin expression is thus not restricted to neural progenitors but persists at lower levels in some newborn neurons for 2-3 days. We found that nestin-expressing neurons have smaller growth cones, suggesting that nestin affects cytoskeletal dynamics. Nestin, unlike other intermediate filament subtypes, regulates cdk5 kinase. Cdk5 activity is induced by the repulsive guidance cue Sema3a leading to growth cone collapse in vitro. Therefore, we tested whether nestin-expressing neurons showed altered responses to Sema3a. We find that nestin-expressing newborn neurons are more sensitive to Sema3a in a roscovitine-sensitive manner, whereas nestin knockdown results in lowered sensitivity to Sema3a. We propose that nestin functions in immature neurons to modulate cdk5 and thereby the Sema3a response. Thus, the transient expression of nestin could allow for temporal modulation of a neuron's response to Sema3a particularly during early axon guidance decisions.

scholarly journals Enhancement of Actin-depolymerizing Factor/Cofilin-dependent Actin Disassembly by Actin-interacting Protein 1 Is Required for Organized Actin Filament Assembly in the Caenorhabditis elegans Body Wall Muscle

2006 ◽  
Vol 17 (5) ◽  
pp. 2190-2199 ◽  
Author(s):  
Kurato Mohri ◽  
Kanako Ono ◽  
Robinson Yu ◽  
Sawako Yamashiro ◽  
Shoichiro Ono
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Muscle Cells ◽  
Actin Depolymerizing Factor ◽  
Interacting Protein ◽  
Cellular Processes ◽  
Cytoskeletal Dynamics ◽  
End Capping

Regulated disassembly of actin filaments is involved in several cellular processes that require dynamic rearrangement of the actin cytoskeleton. Actin-interacting protein (AIP) 1 specifically enhances disassembly of actin-depolymerizing factor (ADF)/cofilin-bound actin filaments. In vitro, AIP1 actively disassembles filaments, caps barbed ends, and binds to the side of filaments. However, how AIP1 functions in the cellular actin cytoskeletal dynamics is not understood. We compared biochemical and in vivo activities of mutant UNC-78 proteins and found that impaired activity of mutant UNC-78 proteins to enhance disassembly of ADF/cofilin-bound actin filaments is associated with inability to regulate striated organization of actin filaments in muscle cells. Six functionally important residues are present in the N-terminal β-propeller, whereas one residue is located in the C-terminal β-propeller, suggesting the presence of two separate sites for interaction with ADF/cofilin and actin. In vitro, these mutant UNC-78 proteins exhibited variable alterations in actin disassembly and/or barbed end-capping activities, suggesting that both activities are important for its in vivo function. These results indicate that the actin-regulating activity of AIP1 in cooperation with ADF/cofilin is essential for its in vivo function to regulate actin filament organization in muscle cells.

scholarly journals Microtubule polymer assembly and transport during axonal elongation.

1991 ◽  
Vol 115 (2) ◽  
pp. 365-379 ◽  
Author(s):  
S S Reinsch ◽  
T J Mitchison ◽  
M Kirschner
Keyword(s):  
Cell Body ◽  
Neural Tube ◽  
Growth Cone ◽  
Cell Stage ◽  
Axonal Elongation ◽  
Axon Elongation ◽  
Coherent Phase ◽  
Polymer Translocation ◽  
Characteristic Manner ◽  
Fluorescent Mark

As axons elongate, tubulin, which is synthesized in the cell body, must be transported and assembled into new structures in the axon. The mechanism of transport and the location of assembly are presently unknown. We report here on the use of tubulin tagged with a photoactivatable fluorescent group to investigate these issues. Photoactivatable tubulin, microinjected into frog embryos at the two-cell stage, is incorporated into microtubules in neurons obtained from explants of the neural tube. When activated by light, a fluorescent mark is made on the microtubules in the axon, and transport and turnover can be visualized directly. We find that microtubules are generated in or near the cell body and continually transported distally as a coherent phase of polymer during axon elongation. This vectorial polymer movement was observed at all levels on the axon, even in the absence of axonal elongation. Measurements of the rate of polymer translocation at various places in the axon suggest that new polymer is formed by intercalary assembly along the axon and assembly at the growth cone in addition to transport of polymer from the cell body. Finally, polymer movement near the growth cone appeared to respond in a characteristic manner to growth cone behavior, while polymer proximally in the axon moved more consistently. These results suggest that microtubule translocation is the principal means of tubulin transport and that translocation plays an important role in generating new axon structure at the growth cone.

scholarly journals The regulation of SIRT2 function by cyclin-dependent kinases affects cell motility

2008 ◽  
Vol 180 (5) ◽  
pp. 915-929 ◽  
Author(s):  
Ruwin Pandithage ◽  
Richard Lilischkis ◽  
Kai Harting ◽  
Alexandra Wolf ◽  
Britta Jedamzik ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Cell Cycle Progression ◽  
Cyclin E ◽  
Loss Of Function ◽  
Cyclin Dependent Kinases ◽  
Expression Arrays ◽  
Cellular Processes ◽  
Growth Cone Collapse ◽  
Cytoskeletal Dynamics

Cyclin-dependent kinases (Cdks) fulfill key functions in many cellular processes, including cell cycle progression and cytoskeletal dynamics. A limited number of Cdk substrates have been identified with few demonstrated to be regulated by Cdk-dependent phosphorylation. We identify on protein expression arrays novel cyclin E–Cdk2 substrates, including SIRT2, a member of the Sirtuin family of NAD+-dependent deacetylases that targets α-tubulin. We define Ser-331 as the site phosphorylated by cyclin E–Cdk2, cyclin A–Cdk2, and p35–Cdk5 both in vitro and in cells. Importantly, phosphorylation at Ser-331 inhibits the catalytic activity of SIRT2. Gain- and loss-of-function studies demonstrate that SIRT2 interfered with cell adhesion and cell migration. In postmitotic hippocampal neurons, neurite outgrowth and growth cone collapse are inhibited by SIRT2. The effects provoked by SIRT2, but not those of a nonphosphorylatable mutant, are antagonized by Cdk-dependent phosphorylation. Collectively, our findings identify a posttranslational mechanism that controls SIRT2 function, and they provide evidence for a novel regulatory circuitry involving Cdks, SIRT2, and microtubules.

scholarly journals Heimdallarchaea encodes profilin with eukaryotic-like actin regulation and polyproline binding

2020 ◽  
Author(s):  
Sabeen Survery ◽  
Fredrik Hurtig ◽  
Syed Razaul Haq ◽  
Ann-Christin Lindås ◽  
Celestine N. Chi
Keyword(s):  
Actin Polymerization ◽  
Eukaryotic Cell ◽  
Membrane Remodeling ◽  
Cellular Processes ◽  
Filament Assembly ◽  
Terminal Loop ◽  
Cellular Cytoskeleton ◽  
Cytoskeleton Dynamics

AbstractThe evolutionary events which led to the first eukaryotic cell are still controversial1-4. The Asgard genome encodes a variety of eukaryotic signature proteins previously unseen in prokaryotes. Functional and structural characterization of these proteins is beginning to shed light on the complexity and pedigree of the ancestral eukaryotic cell5,6. In eukaryotes, the key cytoskeletal protein actin is important for diverse cellular processes such as membrane remodeling and cell motility7. Dynamic polymerization of actin provides both structure and generates the force which drives motility and membrane remodeling. These processes demand rapid filament assembly and disassembly on microsecond timescales. In eukaryotes, a variety of highly adapted proteins including gelsolin, profilin, VASP, ARP2/3 and signaling molecules (Phosphatidylinositol-4,5-bisphosphate (PIP2)) are crucial for organizing cellular cytoskeleton dynamics. Amongst others, the Asgard genomes encode predicted putative profilin homologues that regulate eukaryotic actin polymerization in vitro5,8. Interestingly, Asgard profilins appear to be regulated by PIP2, but not by polyproline rich motifs which are important for recruitment of actin:profilin complexes in eukaryotes5,9. These findings indicate that the Asgard archaea may have possessed analogous membrane organization to present-day eukaryotes, but that polyproline-mediated profilin regulation may have emerge later in the eukaryotic lineage5. Here, we show that Heimdallarchaeota, a candidate phylum within the Asgard superphylum, encodes a putative profilin (heimProfilin) that interacts with PIP2 and is regulated by polyproline motifs, implicative of an origin predating the rise of the eukaryotes. Additionally, we provide evidence for a novel regulatory mechanism whereby an extended N-terminal loop abolishes PIP2 and polyproline interactions. Lastly, we provide the first evidence for actin polymerization of an Asgard actin homologue. In context, these findings provide further evidence for the existence of a complex cytoskeleton already in Last eukaryotic common ancestor (LECA).

scholarly journals ULTRASTRUCTURE AND FUNCTION OF GROWTH CONES AND AXONS OF CULTURED NERVE CELLS

1971 ◽  
Vol 49 (3) ◽  
pp. 614-635 ◽  
Author(s):  
Kenneth M. Yamada ◽  
Brian S. Spooner ◽  
Norman K. Wessells
Keyword(s):  
Growth Cone ◽  
Smooth Endoplasmic Reticulum ◽  
Growth Cones ◽  
Nerve Cells ◽  
Structural Basis ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Ultrastructural Alteration ◽  
Axon Elongation

Dorsal root ganglion nerve cells undergoing axon elongation in vitro have been analyzed ultrastructurally. The growth cone at the axonal tip contains smooth endoplasmic reticulum, vesicles, neurofilaments, occasional microtubules, and a network of 50-A in diameter microfilaments. The filamentous network fills the periphery of the growth cone and is the only structure found in microspikes. Elements of the network are oriented parallel to the axis of microspikes, but exhibit little orientation in the growth cone. Cytochalasin B causes rounding up of growth cones, retraction of microspikes, and cessation of axon elongation. The latter biological effect correlates with an ultrastructural alteration in the filamentous network of growth cones and microspikes. No other organelle appears to be affected by the drug. Removal of cytochalasin allows reinitiation of growth cone-microspike activity, and elongation begins anew. Such recovery will occur in the presence of the protein synthesis inhibitor cycloheximide, and in the absence of exogenous nerve growth factor. The neurofilaments and microtubules of axons are regularly spaced. Fine filaments indistinguishable from those in the growth cone interconnect neurofilaments, vesicles, microtubules, and plasma membrane. This filamentous network could provide the structural basis for the initiation of lateral microspikes and perhaps of collateral axons, besides playing a role in axonal transport.

Long noncoding RNA OIP5-AS1 overexpression promotes viability and inhibits high glucose-induced oxidative stress of cardiomyocytes by targeting microRNA-34a/SIRT1 axis in diabetic cardiomyopathy

2020 ◽  
Vol 21 ◽  
Author(s):  
Haiyun Sun ◽  
Chong Wang ◽  
Ying Zhou ◽  
Xingbo Cheng
Keyword(s):  
Oxidative Stress ◽  
Protein Expression ◽  
Diabetic Cardiomyopathy ◽  
High Glucose ◽  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Luciferase Reporter ◽  
H9c2 Cells ◽  
Promoting Effect

Objective: Diabetic cardiomyopathy (DCM) is an important complication of diabetes. This study was attempted to discover the effects of long noncoding RNA OIP5-AS1 (OIP5-AS1) on the viability and oxidative stress of cardiomyocyte in DCM. Methods: The expression of OIP5-AS1 and microRNA-34a (miR-34a) in DCM was detected by qRT-PCR. In vitro, DCM was simulated by high glucose (HG, 30 mM) treatment in H9c2 cells. The viability of HG (30 mM)-treated H9c2 cells was examined by MTT assay. The reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA) levels were used to evaluate the oxidative stress of HG (30 mM)-treated H9c2 cells. Dual-luciferase reporter assay was used to confirm the interactions among OIP5-AS1, miR-34a and SIRT1. Western blot was applied to analyze the protein expression of SIRT1. Results: The expression of OIP5-AS1 was down-regulated in DCM, but miR-34a was up-regulated. The functional experiment stated that OIP5-AS1 overexpression increased the viability and SOD level, while decreased the ROS and MDA levels in HG (30 mM)-treated H9c2 cells. The mechanical experiment confirmed that OIP5-AS1 and SIRT1 were both targeted by miR-34a with the complementary binding sites at 3′UTR. MiR-34a overexpression inhibited the protein expression of SIRT1. In the feedback experiments, miR-34a overexpression or SIRT1 inhibition weakened the promoting effect on viability, and mitigated the reduction effect on oxidative stress caused by OIP5-AS1 overexpression in HG (30 mM)-treated H9c2 cells. Conclusions: OIP5-AS1 overexpression enhanced viability and attenuated oxidative stress of cardiomyocyte via regulating miR-34a/SIRT1 axis in DCM, providing a new therapeutic target for DCM.

scholarly journals Cyr61 promotes Schwann cell proliferation and migration via αvβ3 integrin

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhenghui Cheng ◽  
Yawen Zhang ◽  
Yinchao Tian ◽  
Yuhan Chen ◽  
Fei Ding ◽  
...  
Keyword(s):  
Nerve Injury ◽  
Peripheral Nerves ◽  
Molecular Mechanisms ◽  
Αvβ3 Integrin ◽  
Promoting Effect ◽  
Ccn Family ◽  
And Migration ◽  
Proliferation And Migration

Abstract Background Schwann cells (SCs) play a crucial role in the repair of peripheral nerves. This is due to their ability to proliferate, migrate, and provide trophic support to axon regrowth. During peripheral nerve injury, SCs de-differentiate and reprogram to gain the ability to repair nerves. Cysteine-rich 61 (Cyr61/CCN1) is a member of the CCN family of matrix cell proteins and have been reported to be abundant in the secretome of repair mediating SCs. In this study we investigate the function of Cyr61 in SCs. Results We observed Cyr61 was expressed both in vivo and in vitro. The promoting effect of Cyr61 on SC proliferation and migration was through autocrine and paracrine mechanisms. SCs expressed αvβ3 integrin and the effect of Cyr61 on SC proliferation and migration could be blocked via αvβ3 integrin. Cyr61 could influence c-Jun protein expression in cultured SCs. Conclusions In this study, we found that Cyr61 promotes SC proliferation and migration via αvβ3 integrin and regulates c-Jun expression. Our study contributes to the understanding of cellular and molecular mechanisms underlying SC’s function during nerve injury, and thus, may facilitate the regeneration of peripheral nerves after injury.

scholarly journals Hyperoside promotes pollen tube growth by regulating the depolymerization effect of actin-depolymerizing factor 1 on microfilaments in okra

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Biying Dong ◽  
Qing Yang ◽  
Zhihua Song ◽  
Lili Niu ◽  
Hongyan Cao ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Germination ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Actin Depolymerizing Factor ◽  
Specific Mechanism ◽  
Promoting Effect ◽  
New Research

AbstractMature pollen germinates rapidly on the stigma, extending its pollen tube to deliver sperm cells to the ovule for fertilization. The success of this process is an important factor that limits output. The flavonoid content increased significantly during pollen germination and pollen tube growth, which suggests it may play an important role in these processes. However, the specific mechanism of this involvement has been little researched. Our previous research found that hyperoside can prolong the flowering period of Abelmoschus esculentus (okra), but its specific mechanism is still unclear. Therefore, in this study, we focused on the effect of hyperoside in regulating the actin-depolymerizing factor (ADF), which further affects the germination and growth of pollen. We found that hyperoside can prolong the effective pollination period of okra by 2–3-fold and promote the growth of pollen tubes in the style. Then, we used Nicotiana benthamiana cells as a research system and found that hyperoside accelerates the depolymerization of intercellular microfilaments. Hyperoside can promote pollen germination and pollen tube elongation in vitro. Moreover, AeADF1 was identified out of all AeADF genes as being highly expressed in pollen tubes in response to hyperoside. In addition, hyperoside promoted AeADF1-mediated microfilament dissipation according to microfilament severing experiments in vitro. In the pollen tube, the gene expression of AeADF1 was reduced to 1/5 by oligonucleotide transfection. The decrease in the expression level of AeADF1 partially reduced the promoting effect of hyperoside on pollen germination and pollen tube growth. This research provides new research directions for flavonoids in reproductive development.

scholarly journals MYL6B drives the capabilities of proliferation, invasion, and migration in rectal adenocarcinoma through the EMT process

2020 ◽  
Vol 15 (1) ◽  
pp. 522-531
Author(s):  
Jin-Liang Li ◽  
Zai-Qiu Wang ◽  
Xiao-Li Sun
Keyword(s):  
Western Blot ◽  
Cell Apoptosis ◽  
Rectal Adenocarcinoma ◽  
Drug Application ◽  
Biological Significance ◽  
Expression Level ◽  
Cell Counting ◽  
Migration And Invasion ◽  
Promoting Effect

AbstractObjectiveThis study was designed to explore the biological significance of myosin light chain 6B (MYL6B) in rectal adenocarcinoma.MethodsProfiles on the Oncomine dataset, GEPIA website, and UALCAN-TCGA database were searched to assess the MYL6B expression level in rectal adenocarcinoma tissues and normal tissues. After MYL6B knockdown using siRNA strategy, cell counting kit-8 (CCK-8) and transwell assays were conducted to measure cell proliferation, migration and invasion, respectively. Flow cytometry analysis was conducted to assess cell apoptosis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blot were performed to detect the expression level of mRNAs and proteins.ResultsThe data showed that overexpression of MYL6B was observed in rectal adenocarcinoma tissues and correlated with a poor prognosis of patients. Functional in vitro experiments revealed that MYL6B knockdown could inhibit proliferation, migration, and invasion of rectal adenocarcinoma cells, while promote cell apoptosis. Moreover, western blot analysis suggested that increased expression of E-cadherin and decreased expression of N-cadherin and Vimentin were induced by si-MYL6B.ConclusionIn summary, this study elaborated on the promoting effect of MYL6B in rectal adenocarcinoma progression, thus providing novel insight for strategies of clinical diagnosis and drug application in the future clinical study.

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