scholarly journals Click-xylosides overcome neurotoxic effects of reactive astrocytes and promote neuronal growth in a cell culture model of brain injury

2018 ◽  
Author(s):  
Swarup Vimal ◽  
Balagurunathan Kuberan
Keyword(s):  
Brain Injury ◽  
Hippocampal Neurons ◽  
Critical Role ◽  
Scar Tissue ◽  
Reactive Astrocyte ◽  
Neuronal Growth ◽  
Molecular Approaches ◽  
A Cell ◽  
Excessive Secretion

AbstractAstrocytes, upon activation in response to brain injury, play a critical role in protecting neurons by limiting inflammation through the excessive secretion of many soluble factors, such as, chondroitin sulfate proteoglycans (CSPGs). Unfortunately, excessive CSPGs paradoxically prohibit neuronal recovery and growth, and eventually constitute a scar tissue. Many studies have attempted to overcome this barrier through various molecular approaches including the removal of inhibitory CSPGs by applying chondroitinase enzymes. In this study, we examined whether click-xylosides, which serve as primers of glycosaminoglycan (GAG) biosynthesis, can compete with endogenous inhibitory CSPGs for GAG assembly by serving as decoy molecules and thereby potentially reverse reactive astrocyte mediated neuronal growth inhibition. We investigated the axonal growth of hippocampal neurons in the presence of xyloside treated and untreated reactive astrocyte-conditioned media as a model recapitulating brain injury. Click-xylosides were found to interfere with the GAG biosynthetic machinery in astrocytes and reduced the amount of secreted inhibitory CSPGs by competing with endogenous assembly sites. The extent of underglycosylation was directly related to the outgrowth of hippocampal neurons. Overall, this study suggests that click-xylosides are promising therapeutic agents to treat CNS injuries and warrants further in vivo investigations.

scholarly journals Cophosphorylation of amphiphysin I and dynamin I by Cdk5 regulates clathrin-mediated endocytosis of synaptic vesicles

2003 ◽  
Vol 163 (4) ◽  
pp. 813-824 ◽  
Author(s):  
Kazuhito Tomizawa ◽  
Satoshi Sunada ◽  
Yun-Fei Lu ◽  
Yoshiya Oda ◽  
Masahiro Kinuta ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Critical Role ◽  
Ring Formation ◽  
Free System ◽  
Rich Domain ◽  
A Cell ◽  
Dynamin I ◽  
Deficient Mice

It has been thought that clathrin-mediated endocytosis is regulated by phosphorylation and dephosphorylation of many endocytic proteins, including amphiphysin I and dynamin I. Here, we show that Cdk5/p35-dependent cophosphorylation of amphiphysin I and dynamin I plays a critical role in such processes. Cdk5 inhibitors enhanced the electric stimulation–induced endocytosis in hippocampal neurons, and the endocytosis was also enhanced in the neurons of p35-deficient mice. Cdk5 phosphorylated the proline-rich domain of both amphiphysin I and dynamin I in vitro and in vivo. Cdk5-dependent phosphorylation of amphiphysin I inhibited the association with β-adaptin. Furthermore, the phosphorylation of dynamin I blocked its binding to amphiphysin I. The phosphorylation of each protein reduced the copolymerization into a ring formation in a cell-free system. Moreover, the phosphorylation of both proteins completely disrupted the copolymerization into a ring formation. Finally, phosphorylation of both proteins was undetectable in p35-deficient mice.

scholarly journals A cell type-selective apoptosis-inducing small molecule for the treatment of brain cancer

2019 ◽  
Vol 116 (13) ◽  
pp. 6435-6440 ◽  
Author(s):  
Natasha C. Lucki ◽  
Genaro R. Villa ◽  
Naja Vergani ◽  
Michael J. Bollong ◽  
Brittney A. Beyer ◽  
...  
Keyword(s):  
Small Molecule ◽  
Brain Cancer ◽  
Critical Role ◽  
Tumor Formation ◽  
Tumor Xenograft ◽  
Drug Candidate ◽  
Cell Type ◽  
Caspase 1 ◽  
A Cell

Glioblastoma multiforme (GBM; grade IV astrocytoma) is the most prevalent and aggressive form of primary brain cancer. A subpopulation of multipotent cells termed GBM cancer stem cells (CSCs) play a critical role in tumor initiation, tumor maintenance, metastasis, drug resistance, and recurrence following surgery. Here we report the identification of a small molecule, termed RIPGBM, from a cell-based chemical screen that selectively induces apoptosis in multiple primary patient-derived GBM CSC cultures. The cell type-dependent selectivity of this compound appears to arise at least in part from redox-dependent formation of a proapoptotic derivative, termed cRIPGBM, in GBM CSCs. cRIPGBM induces caspase 1-dependent apoptosis by binding to receptor-interacting protein kinase 2 (RIPK2) and acting as a molecular switch, which reduces the formation of a prosurvival RIPK2/TAK1 complex and increases the formation of a proapoptotic RIPK2/caspase 1 complex. In an orthotopic intracranial GBM CSC tumor xenograft mouse model, RIPGBM was found to significantly suppress tumor formation in vivo. Our chemical genetics-based approach has identified a drug candidate and a potential drug target that provide an approach to the development of treatments for this devastating disease.

scholarly journals The Protein Dendrite Arborization and Synapse Maturation 1 (Dasm-1) Is Dispensable for Dendrite Arborization

2008 ◽  
Vol 28 (8) ◽  
pp. 2782-2791 ◽  
Author(s):  
Archana Mishra ◽  
Boris Knerr ◽  
Sónia Paixão ◽  
Edgar R. Kramer ◽  
Rüdiger Klein
Keyword(s):  
Hippocampal Neurons ◽  
Critical Role ◽  
Dendritic Tree ◽  
Dendrite Growth ◽  
Immunoglobulin Superfamily ◽  
Genetic Ablation ◽  
Neuronal Connections ◽  
Synapse Maturation

ABSTRACT The development of a highly branched dendritic tree is essential for the establishment of functional neuronal connections. The evolutionarily conserved immunoglobulin superfamily member, the protein dendrite arborization and synapse maturation 1 (Dasm-1) is thought to play a critical role in dendrite formation of dissociated hippocampal neurons. RNA interference-mediated Dasm-1 knockdown was previously shown to impair dendrite, but not axonal, outgrowth and branching (S. H. Shi, D. N. Cox, D. Wang, L. Y. Jan, and Y. N. Jan, Proc. Natl. Acad. Sci. USA 101:13341-13345, 2004). Here, we report the generation and analysis of Dasm-1 null mice. We find that genetic ablation of Dasm-1 does not interfere with hippocampal dendrite growth and branching in vitro and in vivo. Moreover, the absence of Dasm-1 does not affect the modulation of dendritic outgrowth induced by brain-derived neurotrophic factor. Importantly, the previously observed impairment in dendrite growth after Dasm-1 knockdown is also observed when the Dasm-1 knockdown is performed in cultured hippocampal neurons from Dasm-1 null mice. These findings indicate that the dendrite arborization phenotype was caused by off-target effects and that Dasm-1 is dispensable for hippocampal dendrite arborization.

scholarly journals The ATF6β-calreticulin axis promotes neuronal survival under endoplasmic reticulum stress and excitotoxicity

2021 ◽  
Author(s):  
Dinh Thi Nguyen ◽  
Thuong Manh Le ◽  
Tsuyoshi Hattori ◽  
Mika Takarada-Iemata ◽  
Hiroshi Ishii ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Hippocampal Neurons ◽  
Neuronal Survival ◽  
Binding Capacity ◽  
Critical Role ◽  
Er Stress Response ◽  
The Central Nervous System ◽  
The Brain

AbstractWhile ATF6α plays a central role in the endoplasmic reticulum (ER) stress response, the function of ATF6β is largely unknown. Here, we demonstrate that ATF6β is highly expressed in the hippocampus of the brain, and specifically regulates the expression of calreticulin, a molecular chaperone in the ER with a high Ca2+-binding capacity. Calreticulin expression was reduced to ~50% in the central nervous system of Atf6b−/− mice, and restored by ATF6β. Analysis using cultured hippocampal neurons revealed that ATF6β deficiency reduced Ca2+ stores in the ER and enhanced ER stress-induced death, which was rescued by ATF6β, calreticulin, Ca2+-modulating reagents such as BAPTA-AM and 2-APB, and ER stress inhibitor salubrinal. In vivo, kainate-induced neuronal death was enhanced in hippocampi of Atf6b−/− and Calr+/− mice, and restored by 2-APB and salubrinal. These results suggest that the ATF6β-calreticulin axis plays a critical role in the neuronal survival by improving Ca2+ homeostasis under ER stress.

scholarly journals Hypoxic mitophagy regulates mitochondrial quality and platelet activation and determines severity of I/R heart injury

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Weilin Zhang ◽  
He Ren ◽  
Chunling Xu ◽  
Chongzhuo Zhu ◽  
Hao Wu ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Ischemia Reperfusion ◽  
Critical Role ◽  
Acute Ischemia ◽  
Dependent Manner ◽  
Genetic Ablation ◽  
A Cell ◽  
Novel Strategy

Mitochondrial dysfunction underlies many prevalent diseases including heart disease arising from acute ischemia/reperfusion (I/R) injury. Here, we demonstrate that mitophagy, which selectively removes damaged or unwanted mitochondria, regulated mitochondrial quality and quantity in vivo. Hypoxia induced extensive mitochondrial degradation in a FUNDC1-dependent manner in platelets, and this was blocked by in vivo administration of a cell-penetrating peptide encompassing the LIR motif of FUNDC1 only in wild-type mice. Genetic ablation of Fundc1 impaired mitochondrial quality and increased mitochondrial mass in platelets and rendered the platelets insensitive to hypoxia and the peptide. Moreover, hypoxic mitophagy in platelets protected the heart from worsening of I/R injury. This represents a new mechanism of the hypoxic preconditioning effect which reduces I/R injury. Our results demonstrate a critical role of mitophagy in mitochondrial quality control and platelet activation, and suggest that manipulation of mitophagy by hypoxia or pharmacological approaches may be a novel strategy for cardioprotection.

scholarly journals Enhanced angiogenesis by the hyaluronic acid hydrogels immobilized with a VEGF mimetic peptide in a traumatic brain injury model in rats

2019 ◽  
Vol 6 (6) ◽  
pp. 325-334 ◽  
Author(s):  
Jiaju Lu ◽  
Fengyi Guan ◽  
Fuzhai Cui ◽  
Xiaodan Sun ◽  
Lingyun Zhao ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Brain Injury ◽  
Three Dimensional ◽  
Scar Tissue ◽  
Mimetic Peptide ◽  
Injury Model ◽  
Scaffold Structure ◽  
Neurovascular Niche

Abstract Angiogenesis plays an important role in brain injury repair, which contributes to the reconstruction of regenerative neurovascular niche for promoting axonal regeneration in the lesion area. As a major component of developing brain extracellular matrix, hyaluronic acid (HA) has attracted more attention as a supporting matrix for brain repair. In the present study, HA-KLT hydrogel was developed via modifying HA with a VEGF mimetic peptide of KLT (KLTWQELYQLKYKGI). The characterization of the hydrogel shows that it could provide a porous, three-dimensional scaffold structure, which has a large specific surface area available for cell adhesion and interaction. Compared with the unmodified HA hydrogel, the HA-KLT hydrogel could effectively promote the attachment, spreading and proliferation of endothelial cells in vitro. Furthermore, the pro-angiogenic ability of hydrogels in vivo was evaluated by implanting them into the lesion cavities in the injured rat brain. Our results showed that the hydrogels could form a permissive interface with the host tissues at 4 weeks after implantation. Moreover, they could efficiently inhibit the formation of glial scars at the injured sites. The HA-KLT hydrogel could significantly increase the expression of endoglin/CD105 and promote the formation of blood vessels, suggesting that HA-KLT hydrogel promoted angiogenesis in vivo. Collectively, the HA-KLT hydrogel has the potential to repair brain defects by promoting angiogenesis and inhibiting the formation of glial-derived scar tissue.

scholarly journals Cdc7-mediated phosphorylation of Cse4 regulates high fidelity chromosome segregation in budding yeast

2021 ◽  
pp. mbc.E21-06-0323
Author(s):  
Prashant K. Mishra ◽  
Henry Wood ◽  
John Stanton ◽  
Wei-Chun Au ◽  
Jessica R. Eisenstatt ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Critical Role ◽  
High Fidelity ◽  
Dependent Manner ◽  
Growth Defects ◽  
A Cell ◽  
Cdc7 Kinase ◽  
Cycle Dependent

Faithful chromosome segregation maintains chromosomal stability as errors in this process contribute to chromosomal instability (CIN) which has been observed in many diseases including cancer. Epigenetic regulation of kinetochore proteins such as Cse4 (CENP-A in humans) plays a critical role in high fidelity chromosome segregation. Here we show that Cse4 is a substrate of evolutionarily conserved Cdc7 kinase, and that Cdc7-mediated phosphorylation of Cse4 prevents CIN. We determined that Cdc7 phosphorylates Cse4 in vitro and interacts with Cse4 in vivo in a cell cycle dependent manner. Cdc7 is required for kinetochore integrity as reduced levels of CEN-associated Cse4, a faster exchange of Cse4 at the metaphase kinetochores and defects in chromosome segregation are observed in a cdc7-7 strain. Phosphorylation of Cse4 by Cdc7 is important for cell survival as constitutive association of a kinase dead variant of Cdc7 ( cdc7-kd) with Cse4 at the kinetochore leads to growth defects. Moreover, phosphodeficient mutations of Cse4 for consensus Cdc7 target sites contribute to CIN phenotype. In summary, our results have defined a role for Cdc7-mediated phosphorylation of Cse4 in faithful chromosome segregation.

scholarly journals Non-REM sleep facilitates consolidation of contextual fear memory through temporal coding among hippocampal neurons

2020 ◽  
Author(s):  
Quinton M. Skilling ◽  
Brittany C. Clawson ◽  
Bolaji Eniwaye ◽  
James Shaver ◽  
Nicolette Ognjanovski ◽  
...  
Keyword(s):  
Memory Consolidation ◽  
Hippocampal Neurons ◽  
Critical Role ◽  
Nrem Sleep ◽  
Spike Timing ◽  
Temporal Coding ◽  
Network Activity ◽  
Prior Learning ◽  
Information Encoding

SummarySleep plays a critical role in memory consolidation, although the exact mechanisms mediating this process are unknown. Combining computational and in vivo experimental approaches, we test the hypothesis that reduced cholinergic input to the hippocampus during non-rapid eye movement (NREM) sleep generates stable spike timing relationships between neurons. We find that the order of firing among neurons during a period of NREM sleep reflects their relative firing rates during prior wake, and changes as a function of prior learning. We show that learning-dependent pattern formation (e.g. “replay”) in the hippocampus during NREM, together with spike timing dependent plasticity (STDP), restructures network activity in a manner similar to that observed in brain circuits across periods of sleep. This suggests that sleep actively promotes memory consolidation by switching the network from rate-based to firing phase-based information encoding.

scholarly journals NF-κB-Dependent Assembly of an Enhanceosome-Like Complex on the Promoter Region of Apoptosis Inhibitor Bfl-1/A1

2003 ◽  
Vol 23 (8) ◽  
pp. 2749-2761 ◽  
Author(s):  
Leonard C. Edelstein ◽  
Lynn Lagos ◽  
Matthew Simmons ◽  
Hemamalini Tirumalai ◽  
Céline Gélinas
Keyword(s):  
Transcription Factors ◽  
T Cell Activation ◽  
Promoter Region ◽  
Cell Activation ◽  
Critical Role ◽  
Gene Activation ◽  
Regulatory Region ◽  
A Cell ◽  
Basal Transcription Factors

ABSTRACT Expression of the prosurvival Bcl-2 homologue Bfl-1/A1 is induced by NF-κB-activating stimuli, while B and T cells from c-rel knockout mice show an absolute defect in bfl-1/a1 gene activation. Here, we demonstrate NF-κB-dependent assembly of an enhanceosome-like complex on the promoter region of bfl-1. Binding of NF-κB subunit c-Rel to DNA nucleated the concerted binding of transcription factors AP-1 and C/EBPβ to the 5′-regulatory region of bfl-1. Optimal stability of the complex was dependent on proper orientation and phasing of the NF-κB site. Chromatin immunoprecipitation analyses demonstrated that T-cell activation triggers in vivo binding of endogenous c-Rel, c-Jun, C/EBPβ, and HMG-IC to the bfl-1 regulatory region, coincident with selective recruitment of coactivators TAFII250 and p300, SWI/SNF chromatin remodeling factor component BRG-1, and basal transcription factors TATA-binding protein (TBP) and TFIIB, as well as hyperacetylation of histones H3 and H4. These results highlight a critical role for NF-κB in bfl-1 transcription and point to the need for a complex and precise regulatory network to control bfl-1 expression. To our knowledge, this is the first demonstration of enhanceosome-mediated regulation of a cell death inhibitor.

scholarly journals Astrocytic Sonic Hedgehog Alleviates Intracerebral Hemorrhagic Brain Injury via Modulation of Blood-Brain Barrier Integrity

2020 ◽  
Vol 14 ◽  
Author(s):  
Gebeili Xing ◽  
Tianman Zhao ◽  
Xiyue Zhang ◽  
He Li ◽  
Xiuping Li ◽  
...  
Keyword(s):  
Brain Injury ◽  
Signaling Pathway ◽  
Blood Brain Barrier ◽  
Sonic Hedgehog ◽  
Critical Role ◽  
Brain Barrier ◽  
Shh Signaling ◽  
Blood Brain

Background: Intracerebral hemorrhage (ICH) is a fatal subtype of stroke that lacks effective therapy. Blood-brain barrier (BBB) damage is a hallmark of ICH-induced brain injury that leads to edema formation, leukocytes infiltration, influx of blood components into the perihematomal (PHE) region, and eventually brain injury. Astrocytes are essential for the formation and maintenance of the BBB by providing secreted molecules that contribute to the association between these cells. Sonic hedgehog (SHH) derived from astrocytes promotes the maturity and integrity of the BBB by upregulating tight junctions (TJs) in brain capillary endothelial cells (ECs). However, the effect of SHH on BBB in ICH has not been investigated.Methods: Cyclopamine (CYC) is a potent, selective inhibitor that specifically blocks the SHH signaling pathway. Here, we used pharmacological inhibitions (CYC and its derivatives) to determine a critical role of the SHH signaling pathway in promoting BBB integrity after ICH by mechanisms of regulating the TJ proteins in vivo and in vitro.Results: The expression of astrocytic SHH was upregulated in mouse brains after ICH. Compared with the vehicle-treated group, inhibition of the SHH signaling pathway with CYC and its derivatives treatments aggravated neurological function deficits, brain edema, hematoma volume, and BBB impairment by downregulating TJs in ECs through the SHH-Gli-1 axis in vivo and in vitro.Conclusions: SHH signaling pathway at the level of the BBB provides a barrier-promoting effect, suggesting that the SHH signaling pathway may function as a potential therapeutic target for restoring BBB function in ICH.

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