scholarly journals Defects in Axonal Elongation and Neuronal Migration in Mice with Disrupted tau and map1b Genes

2000 ◽  
Vol 150 (5) ◽  
pp. 989-1000 ◽  
Author(s):  
Yosuke Takei ◽  
Junlin Teng ◽  
Akihiro Harada ◽  
Nobutaka Hirokawa
Keyword(s):  
Knockout Mice ◽  
Neuronal Migration ◽  
Hippocampal Neurons ◽  
Primary Cultures ◽  
Double Knockout ◽  
Microtubule Organization ◽  
Axonal Elongation ◽  
Microtubule Associated Proteins ◽  
Associated Proteins

Tau and MAP1B are the main members of neuronal microtubule-associated proteins (MAPs), the functions of which have remained obscure because of a putative functional redundancy (Harada, A., K. Oguchi, S. Okabe, J. Kuno, S. Terada, T. Ohshima, R. Sato-Yoshitake, Y. Takei, T. Noda, and N. Hirokawa. 1994. Nature. 369:488–491; Takei, Y., S. Kondo, A. Harada, S. Inomata, T. Noda, and N. Hirokawa. 1997. J. Cell Biol. 137:1615–1626). To unmask the role of these proteins, we generated double-knockout mice with disrupted tau and map1b genes and compared their phenotypes with those of single-knockout mice. In the analysis of mice with a genetic background of predominantly C57Bl/6J, a hypoplastic commissural axon tract and disorganized neuronal layering were observed in the brains of the tau+/+map1b−/− mice. These phenotypes are markedly more severe in tau−/−map1b−/− double mutants, indicating that tau and MAP1B act in a synergistic fashion. Primary cultures of hippocampal neurons from tau−/−map1b−/− mice showed inhibited axonal elongation. In these cells, a generation of new axons via bundling of microtubules at the neck of the growth cones appeared to be disturbed. Cultured cerebellar neurons from tau−/−map1b−/− mice showed delayed neuronal migration concomitant with suppressed neurite elongation. These findings indicate the cooperative functions of tau and MAP1B in vivo in axonal elongation and neuronal migration as regulators of microtubule organization.

scholarly journals Synergistic effects of MAP2 and MAP1B knockout in neuronal migration, dendritic outgrowth, and microtubule organization

2001 ◽  
Vol 155 (1) ◽  
pp. 65-76 ◽  
Author(s):  
Junlin Teng ◽  
Yosuke Takei ◽  
Akihiro Harada ◽  
Takao Nakata ◽  
Jianguo Chen ◽  
...  
Keyword(s):  
Neuronal Migration ◽  
Hippocampal Neurons ◽  
Synergistic Effects ◽  
Primary Cultures ◽  
Perinatal Period ◽  
Cortical Layer ◽  
Microtubule Organization ◽  
Dendritic Morphogenesis

MAP1B and MAP2 are major members of neuronal microtubule-associated proteins (MAPs). To gain insights into the function of MAP2 in vivo, we generated MAP2-deficient (map2−/−) mice. They developed without any apparent abnormalities, which indicates that MAP2 is dispensable in mouse survival. Because previous reports suggest a functional redundancy among MAPs, we next generated mice lacking both MAP2 and MAP1B to test their possible synergistic functions in vivo. Map2−/−map1b−/− mice died in their perinatal period. They showed not only fiber tract malformations but also disrupted cortical patterning caused by retarded neuronal migration. In spite of this, their cortical layer maintained an “inside-out” pattern. Detailed observation of primary cultures of hippocampal neurons from map2−/−map1b−/− mice revealed inhibited microtubule bundling and neurite elongation. In these neurons, synergistic effects caused by the loss of MAP2 and MAP1B were more apparent in dendrites than in axons. The spacing of microtubules was reduced significantly in map2−/−map1b−/− mice in vitro and in vivo. These results suggest that MAP2 and MAP1B have overlapping functions in neuronal migration and neurite outgrowth by organizing microtubules in developing neurons both for axonal and dendritic morphogenesis but more dominantly for dendritic morphogenesis.

scholarly journals NCAM2 Regulates Dendritic and Axonal Differentiation through the Cytoskeletal Proteins MAP2 and 14-3-3

2020 ◽  
Vol 30 (6) ◽  
pp. 3781-3799
Author(s):  
Antoni Parcerisas ◽  
Lluís Pujadas ◽  
Alba Ortega-Gascó ◽  
Bartomeu Perelló-Amorós ◽  
Ricardo Viais ◽  
...  
Keyword(s):  
Cell Biology ◽  
Hippocampal Neurons ◽  
Cytoskeletal Proteins ◽  
In Vivo Studies ◽  
Microtubule Associated Proteins ◽  
Neural Cell Adhesion ◽  
Aberrant Phenotype ◽  
Associated Proteins ◽  
And Migration

Abstract Neural cell adhesion molecule 2 (NCAM2) is involved in the development and plasticity of the olfactory system. Genetic data have implicated the NCAM2 gene in neurodevelopmental disorders including Down syndrome and autism, although its role in cortical development is unknown. Here, we show that while overexpression of NCAM2 in hippocampal neurons leads to minor alterations, its downregulation severely compromises dendritic architecture, leading to an aberrant phenotype including shorter dendritic trees, retraction of dendrites, and emergence of numerous somatic neurites. Further, our data reveal alterations in the axonal tree and deficits in neuronal polarization. In vivo studies confirm the phenotype and reveal an unexpected role for NCAM2 in cortical migration. Proteomic and cell biology experiments show that NCAM2 molecules exert their functions through a protein complex with the cytoskeletal-associated proteins MAP2 and 14-3-3γ and ζ. We provide evidence that NCAM2 depletion results in destabilization of the microtubular network and reduced MAP2 signal. Our results demonstrate a role for NCAM2 in dendritic formation and maintenance, and in neural polarization and migration, through interaction of NCAM2 with microtubule-associated proteins.

scholarly journals CCDC74A/B are K-fiber crosslinkers required for chromosomal alignment

BMC Biology ◽  
2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Haining Zhou ◽  
Tao Zheng ◽  
Tianning Wang ◽  
Qi Li ◽  
Fulin Wang ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Genetic Material ◽  
Fiber Formation ◽  
Microtubule Organization ◽  
Spindle Formation ◽  
Bipolar Spindle ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
Fiber Organization

Abstract Background Spindle microtubule organization, regulated by microtubule-associated proteins, is critical for cell division. Proper organization of kinetochore fiber (K-fiber), connecting spindle poles and kinetochores, is a prerequisite for precise chromosomal alignment and faithful genetic material transmission. However, the mechanisms of K-fiber organization and dynamic maintenance are still not fully understood. Results We reveal that two previously uncharacterized coiled-coil domain proteins CCDC74A and CCDC74B (CCDC74A/B) are spindle-localized proteins in mammalian cells. They bind directly to microtubules through two separate domains and bundle microtubules both in vivo and in vitro. These functions are required for K-fiber organization, bipolar spindle formation, and chromosomal alignment. Moreover, CCDC74A/B form homodimers in vivo, and their self-association activity is necessary for microtubule bundling and K-fiber formation. Conclusions We characterize CCDC74A and CCDC74B as microtubule-associated proteins that localize to spindles and are important K-fiber crosslinkers required for bipolar spindle formation and chromosome alignment.

scholarly journals Normal Hematopoiesis and Inflammatory Responses Despite Discrete Signaling Defects in Gα15 Knockout Mice

2000 ◽  
Vol 20 (3) ◽  
pp. 797-804 ◽  
Author(s):  
I. Davignon ◽  
M. D. Catalina ◽  
D. Smith ◽  
J. Montgomery ◽  
J. Swantek ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Inflammatory Responses ◽  
Trichinella Spiralis ◽  
Primary Cultures ◽  
Hematopoietic Cells ◽  
Embryonic Stem ◽  
Double Knockout ◽  
C5a Receptor ◽  
Α Subunits

ABSTRACT Gα15 activates phospholipase Cβ in response to the greatest variety of agonist-stimulated heptahelical receptors among the four Gq class G-protein α subunits expressed in mammals. Gα15 is primarily expressed in hematopoietic cells in fetal and adult mice. We disrupted the Gα15 gene by homologous recombination in embryonic stem cells to identify its biological functions. Surprisingly, hematopoiesis was normal in Gα15−/− mice, Gα15−/−Gαq−/− double-knockout mice (which express only Gα11 in most hematopoietic cells), and Gα11−/− mice, suggesting functional redundancy in Gq class signaling. Inflammatory challenges, including thioglycolate-induced peritonitis and infection with Trichinella spiralis, stimulated similar responses in Gα15−/− adults and wild-type siblings. Agonist-stimulated Ca2+ release from intracellular stores was assayed to identify signaling defects in primary cultures of thioglycolate-elicited macrophages isolated from Gα15−/− mice. C5a-stimulated phosphoinositide accumulation and Ca2+ release was significantly reduced in Gα15−/− macrophages. Ca2+ signaling was abolished only in mutant cells pretreated with pertussis toxin, suggesting that the C5a receptor couples to both Gα15 and Gαi in vivo. Signaling evoked by other receptors coupled by Gq class α subunits appeared normal in Gα15−/− macrophages. Despite discrete signaling defects, compensation by coexpressed Gq and/or Gi class α subunits may suppress abnormalities in Gα15-deficient mice.

scholarly journals Binding of microtubule-associated protein 1B to LIS1 affects the interaction between dynein and LIS1

2005 ◽  
Vol 389 (2) ◽  
pp. 333-341 ◽  
Author(s):  
Eva M. JiméNez-Mateos ◽  
Francisco Wandosell ◽  
Orly Reiner ◽  
Jesús Avila ◽  
Christian González-Billault
Keyword(s):  
Neuronal Migration ◽  
Hippocampal Neurons ◽  
Morphological Changes ◽  
Molecular Motor ◽  
Cytoskeletal Proteins ◽  
Actin Binding ◽  
Microtubule Associated Proteins ◽  
Neural Processes ◽  
Associated Proteins ◽  
Differential Binding

For neuronal migration to occur, the cell must undergo morphological changes that require modifications of the cytoskeleton. Several different MAPs (microtubule-associated proteins) or actin-binding proteins are proposed to be involved in the migration of neurons. Therefore we have specifically analysed how two members of the MAP family, MAP1B and LIS1 (lissencephaly-related protein 1), interact with one another and participate in neuronal migration. Our results indicate that, in hippocampal neurons, MAP1B and LIS1 co-localize, associate and interact with each another. The interaction between these two MAPs is regulated by the phosphorylation of MAP1B. Furthermore, this interaction interferes with the association between LIS1 and the microtubule-dependent molecular motor, dynein. Clearly, the differential binding of these cytoskeletal proteins could regulate the functions attributed to the LIS1–dynein complex, including those related to extension of the neural processes necessary for neuronal migration.

scholarly journals Stu2p binds tubulin and undergoes an open-to-closed conformational change

2006 ◽  
Vol 172 (7) ◽  
pp. 1009-1022 ◽  
Author(s):  
Jawdat Al-Bassam ◽  
Mark van Breugel ◽  
Stephen C. Harrison ◽  
Anthony Hyman
Keyword(s):  
Conformational Change ◽  
Conformational Transition ◽  
Budding Yeast ◽  
Microtubule Dynamics ◽  
Open Structure ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
The Common

Stu2p from budding yeast belongs to the conserved Dis1/XMAP215 family of microtubule-associated proteins (MAPs). The common feature of proteins in this family is the presence of HEAT repeat–containing TOG domains near the NH2 terminus. We have investigated the functions of the two TOG domains of Stu2p in vivo and in vitro. Our data suggest that Stu2p regulates microtubule dynamics through two separate activities. First, Stu2p binds to a single free tubulin heterodimer through its first TOG domain. A large conformational transition in homodimeric Stu2p from an open structure to a closed one accompanies the capture of a single free tubulin heterodimer. Second, Stu2p has the capacity to associate directly with microtubule ends, at least in part, through its second TOG domain. These two properties lead to the stabilization of microtubules in vivo, perhaps by the loading of tubulin dimers at microtubule ends. We suggest that this mechanism of microtubule regulation is a conserved feature of the Dis1/XMAP215 family of MAPs.

scholarly journals Marliolide Derivative Induces Melanosome Degradation via Nrf2/p62-Mediated Autophagy

2021 ◽  
Vol 22 (8) ◽  
pp. 3995
Author(s):  
Cheong-Yong Yun ◽  
Nahyun Choi ◽  
Jae Un Lee ◽  
Eun Jung Lee ◽  
Ji Young Kim ◽  
...  
Keyword(s):  
Related Factor ◽  
Melanin Pigmentation ◽  
Microtubule Associated Proteins ◽  
Melanocyte Stimulating Hormone ◽  
Associated Proteins ◽  
Autophagy Pathway ◽  
Nrf2 Activator ◽  
Promising Therapeutic Agent

Nuclear factor erythroid 2-related factor 2 (Nrf2), which is linked to autophagy regulation and melanogenesis regulation, is activated by marliolide. In this study, we investigated the effect of a marliolide derivative on melanosome degradation through the autophagy pathway. The effect of the marliolide derivative on melanosome degradation was investigated in α-melanocyte stimulating hormone (α-MSH)-treated melanocytes, melanosome-incorporated keratinocyte, and ultraviolet (UV)B-exposed HRM-2 mice (melanin-possessing hairless mice). The marliolide derivative, 5-methyl-3-tetradecylidene-dihydro-furan-2-one (DMF02), decreased melanin pigmentation by melanosome degradation in α-MSH-treated melanocytes and melanosome-incorporated keratinocytes, evidenced by premelanosome protein (PMEL) expression, but did not affect melanogenesis-associated proteins. The UVB-induced hyperpigmentation in HRM-2 mice was also reduced by a topical application of DMF02. DMF02 activated Nrf2 and induced autophagy in vivo, evidenced by decreased PMEL in microtubule-associated proteins 1A/1B light chain 3B (LC3)-II-expressed areas. DMF02 also induced melanosome degradation via autophagy in vitro, and DMF02-induced melanosome degradation was recovered by chloroquine (CQ), which is a lysosomal inhibitor. In addition, Nrf2 silencing by siRNA attenuated the DMF02-induced melanosome degradation via the suppression of p62. DMF02 induced melanosome degradation in melanocytes and keratinocytes by regulating autophagy via Nrf2-p62 activation. Therefore, Nrf2 activator could be a promising therapeutic agent for reducing hyperpigmentation.

scholarly journals The Impact of Oxytocin on Neurite Outgrowth and Synaptic Proteins in Magel2-Deficient Mice

2020 ◽  
Author(s):  
Alexandra Reichova ◽  
Fabienne Schaller ◽  
Stanislava Bukatova ◽  
Zuzana Bacova ◽  
Françoise Muscatelli ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Hippocampal Neurons ◽  
Synapse Formation ◽  
Primary Cultures ◽  
Synaptic Proteins ◽  
Neuronal Maturation ◽  
Glutamatergic Synapses ◽  
Associated Proteins ◽  
The Impact ◽  
Deficient Mice

AbstractOxytocin contributes to the regulation of cytoskeletal and synaptic proteins and could therefore affect the mechanisms of neurodevelopmental disorders, including autism. Both the Prader-Willi syndrome and Schaaf-Yang syndrome exhibit autistic symptoms involving the MAGEL2 gene. Magel2-deficient mice show a deficit in social behavior that is rescued following postnatal administration of oxytocin. Here, in Magel2-deficient mice, we showed that the neurite outgrowth of primary cultures of immature hippocampal neurons is reduced. Treatment with oxytocin, but not retinoic acid, reversed this abnormality. In the hippocampus of Magel2-deficient pups, we further demonstrated that several transcripts of neurite outgrowth-associated proteins, synaptic vesicle proteins, and cell-adhesion molecules are decreased. In the juvenile stage, when neurons are mature, normalization or even overexpression of most of these markers was observed, suggesting a delay in the neuronal maturation of Magel2-deficient pups. Moreover, we found reduced transcripts of the excitatory postsynaptic marker, Psd95 in the hippocampus and we observed a decrease of PSD95/VGLUT2 colocalization in the hippocampal CA1 and CA3 regions in Magel2-deficient mice, indicating a defect in glutamatergic synapses. Postnatal administration of oxytocin upregulated postsynaptic transcripts in pups; however, it did not restore the level of markers of glutamatergic synapses in Magel2-deficient mice. Overall, Magel2 deficiency leads to abnormal neurite outgrowth and reduced glutamatergic synapses during development, suggesting abnormal neuronal maturation. Oxytocin stimulates the expression of numerous genes involved in neurite outgrowth and synapse formation in early development stages. Postnatal oxytocin administration has a strong effect in development that should be considered for certain neuropsychiatric conditions in infancy.

scholarly journals Prodigiosin-Emerged PI3K/Beclin-1-Independent Pathway Elicits Autophagic Cell Death in Doxorubicin-Sensitive and -Resistant Lung Cancer

2018 ◽  
Vol 7 (10) ◽  
pp. 321 ◽  
Author(s):  
Wei-Jun Chiu ◽  
Shian-Ren Lin ◽  
Yu-Hsin Chen ◽  
May-Jwan Tsai ◽  
Max Leong ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cell Death ◽  
Mammalian Target Of Rapamycin ◽  
Underlying Mechanism ◽  
Beclin 1 ◽  
Class Iii ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
Anti Tumor Activity

Prodigiosin (PG) belongs to a family of prodiginines isolated from gram-negative bacteria. It is a water insoluble red pigment and a potent proapoptotic compound. This study elucidates the anti-tumor activity and underlying mechanism of PG in doxorubicin-sensitive (Dox-S) and doxorubicin-resistant (Dox-R) lung cancer cells. The cytotoxicity and cell death characteristics of PG in two cells were measured by MTT assay, cell cycle analysis, and apoptosis/autophagic marker analysis. Then, the potential mechanism of PG-induced cell death was evaluated through the phosphatidylinositol-4,5-bisphosphate 3-kinase-p85/Protein kinase B /mammalian target of rapamycin (PI3K-p85/Akt/mTOR) and Beclin-1/phosphatidylinositol-4,5-bisphosphate 3-kinase-Class III (Beclin-1/PI3K-Class III) signaling. Finally, in vivo efficacy was examined by intratracheal inoculation and treatment. There was similar cytotoxicity with PG in both Dox-S and Dox-R cells, where the half maximal inhibitory concentrations (IC50) were all in 10 μM. Based on a non-significant increase in the sub-G1 phase with an increase of microtubule-associated proteins 1A/1B light chain 3B-phosphatidylethanolamine conjugate (LC3-II), the cell death of both cells was categorized to achieve autophagy. Interestingly, an increase in cleaved-poly ADP ribose polymerase (cleaved-PARP) also showed the existence of an apoptosis-sensitive subpopulation. In both Dox-S and Dox-R cells, PI3K-p85/Akt/mTOR signaling pathways were reduced, which inhibited autophagy initiation. However, Beclin-1/PI3K-Class III downregulation implicated non-canonical autophagy pathways were involved in PG-induced autophagy. At completion of the PG regimen, tumors accumulated in the mice trachea and were attenuated by PG treatment, which indicated the efficacy of PG for both Dox-S and Dox-R lung cancer. All the above results concluded that PG is a potential chemotherapeutic agent for lung cancer regimens regardless of doxorubicin resistance.

Modulation of microtubule dynamic instability in vivo by brain microtubule associated proteins

1995 ◽  
Vol 108 (4) ◽  
pp. 1679-1689 ◽  
Author(s):  
R. Dhamodharan ◽  
P. Wadsworth
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Instability ◽  
Average Rate ◽  
Stable Maps ◽  
Microtubule Dynamic ◽  
Unit Distance ◽  
Microtubule Associated Proteins ◽  
Heat Stable ◽  
Associated Proteins

Heat-stable brain microtubule associated proteins (MAPs) and purified microtubule associated protein 2 (MAP-2) were microinjected into cultured BSC-1 cells which had been previously injected with rhodamine-labeled tubulin. The dynamic instability behavior of individual microtubules was then examined using low-light-level fluorescence microscopy and quantitative microtubule tracking methods. Both MAP preparations suppressed microtubule dynamics in vivo, by reducing the average rate and extent of both growing and shortening events. The average duration of growing events was not affected. When measured as events/unit time, heat-stable MAPs and MAP-2 did not significantly alter the frequency of rescue; the frequency of catastrophe was decreased approximately two-fold by heat-stable MAPs and MAP-2. When transition frequencies were calculated as events/unit distance, both MAP preparations increased the frequency of rescue, without altering the frequency of catastrophe. The percentage of total time spent in the phases of growth, shrink and pause was determined. Both MAP-2 and heat-stable MAPs decreased the percentage of time spent shortening, increased the percentage of time spent paused, and had no effect on percentage of time spent growing. Heat-stable MAPs increased the average pause duration, decreased the average number of events per minute per microtubule and increased the probability that a paused microtubule would switch to growing rather than shortening. The results demonstrate that addition of MAPs to living cells reduces the dynamic behavior of individual microtubules primarily by suppressing the magnitude of dynamic events and increasing the time spent in pause, where no change in the microtubule length can be detected. The results further suggest that the expression of MAPs directly contributes to cell type-specific microtubule dynamic behavior.

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