scholarly journals ABCA13 dysfunction associated with psychiatric disorders causes impaired cholesterol trafficking

2020 ◽  
pp. jbc.RA120.015997
Author(s):  
Mitsuhiro Nakato ◽  
Naoko Shiranaga ◽  
Maiko Tomioka ◽  
Hitomi Watanabe ◽  
Junko Kurisu ◽  
...  
Keyword(s):  
Psychiatric Disorders ◽  
Cortical Neurons ◽  
Atp Hydrolysis ◽  
Primary Cultures ◽  
Retrograde Transport ◽  
Terminal Region ◽  
Hek293 Cells ◽  
Cholesterol Trafficking ◽  
Abc Protein ◽  
Intracellular Vesicles

ATP-binding cassette subfamily A member 13 (ABCA13) is predicted to be the largest ABC protein, consisting of 5,058 amino acids and a long N-terminal region. Mutations in the ABCA13 gene were reported to increase the susceptibility to schizophrenia, bipolar disorder and major depression. However, little is known about the molecular functions of ABCA13 or how they associate with psychiatric disorders. Here, we examined the biochemical activity of ABCA13 using HEK293 cells transfected with mouse ABCA13. The expression of ABCA13 induced the internalization of cholesterol and gangliosides from the plasma membrane to intracellular vesicles. Cholesterol internalization by ABCA13 required the long N-terminal region and ATP hydrolysis. To examine the physiological roles of ABCA13, we generated Abca13 KO mice using CRISPR/Cas and found that these mice exhibited deficits of prepulse inhibition. Vesicular cholesterol accumulation and synaptic vesicle endocytosis were impaired in primary cultures of Abca13 KO cortical neurons. Furthermore, mutations in ABCA13 gene associated with psychiatric disorders disrupted the protein’s subcellular localization  and impaired cholesterol trafficking. These findings suggest that ABCA13 accelerates cholesterol internalization by endocytic retrograde transport in neurons and that loss-of-this function is associated with the pathophysiology of psychiatric disorders.

scholarly journals Analysis of the Structural Mechanism of ATP Inhibition at the AAA1 Subunit of Cytoplasmic Dynein-1 Using a Chemical “Toolkit”

2021 ◽  
Vol 22 (14) ◽  
pp. 7704
Author(s):  
Sayi’Mone Tati ◽  
Laleh Alisaraie
Keyword(s):  
Binding Affinity ◽  
Atp Hydrolysis ◽  
Critical Role ◽  
Motor Protein ◽  
Structural Data ◽  
Retrograde Transport ◽  
Cytoplasmic Dynein ◽  
Motor Domain ◽  
Conformational Search ◽  
Structural Mechanism

Dynein is a ~1.2 MDa cytoskeletal motor protein that carries organelles via retrograde transport in eukaryotic cells. The motor protein belongs to the ATPase family of proteins associated with diverse cellular activities and plays a critical role in transporting cargoes to the minus end of the microtubules. The motor domain of dynein possesses a hexameric head, where ATP hydrolysis occurs. The presented work analyzes the structure–activity relationship (SAR) of dynapyrazole A and B, as well as ciliobrevin A and D, in their various protonated states and their 46 analogues for their binding in the AAA1 subunit, the leading ATP hydrolytic site of the motor domain. This study exploits in silico methods to look at the analogues’ effects on the functionally essential subsites of the motor domain of dynein 1, since no similar experimental structural data are available. Ciliobrevin and its analogues bind to the ATP motifs of the AAA1, namely, the walker-A (W-A) or P-loop, the walker-B (W-B), and the sensor I and II. Ciliobrevin A shows a better binding affinity than its D analogue. Although the double bond in ciliobrevin A and D was expected to decrease the ligand potency, they show a better affinity to the AAA1 binding site than dynapyrazole A and B, lacking the bond. In addition, protonation of the nitrogen atom in ciliobrevin A and D, as well as dynapyrazole A and B, at the N9 site of ciliobrevin and the N7 of the latter increased their binding affinity. Exploring ciliobrevin A geometrical configuration suggests the E isomer has a superior binding profile over the Z due to binding at the critical ATP motifs. Utilizing the refined structure of the motor domain obtained through protein conformational search in this study exhibits that Arg1852 of the yeast cytoplasmic dynein could involve in the “glutamate switch” mechanism in cytoplasmic dynein 1 in lieu of the conserved Asn in AAA+ protein family.

scholarly journals The Bacterial Enzyme Cas13 Interferes with Neurite Outgrowth from Cultured Cortical Neurons

Toxins ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 262
Author(s):  
Qin-Wei Wu ◽  
Josef P. Kapfhammer
Keyword(s):  
Rna Editing ◽  
Cortical Neurons ◽  
High Efficiency ◽  
Primary Cultures ◽  
Cultured Neurons ◽  
Therapeutic Tool ◽  
Bacterial Enzyme ◽  
Rna Targeting ◽  
Cultured Cortical Neurons ◽  
New Generation

The CRISPR-Cas13 system based on a bacterial enzyme has been explored as a powerful new method for RNA manipulation. Due to the high efficiency and specificity of RNA editing/interference achieved by this system, it is currently being developed as a new therapeutic tool for the treatment of neurological and other diseases. However, the safety of this new generation of RNA therapies is still unclear. In this study, we constructed a vector expressing CRISPR-Cas13 under a constitutive neuron-specific promoter. CRISPR-Cas13 from Leptotrichia wadei was expressed in primary cultures of mouse cortical neurons. We found that the presence of CRISPR-Cas13 impedes the development of cultured neurons. These results show a neurotoxic action of Cas13 and call for more studies to test for and possibly mitigate the toxic effects of Cas13 enzymes in order to improve CRISPR-Cas13-based tools for RNA targeting.

Neuroprotective effects of vitexin by inhibition of NMDA receptors in primary cultures of mouse cerebral cortical neurons

2013 ◽  
Vol 386 (1-2) ◽  
pp. 251-258 ◽  
Author(s):  
Le Yang ◽  
Zhi-ming Yang ◽  
Nan Zhang ◽  
Zhen Tian ◽  
Shui-bing Liu ◽  
...  
Keyword(s):  
Nmda Receptors ◽  
Cortical Neurons ◽  
Primary Cultures ◽  
Neuroprotective Effects ◽  
Cerebral Cortical Neurons

Effects of deep hypothermia on nitric oxide-induced cytotoxicity in primary cultures of cortical neurons

2003 ◽  
Vol 72 (5) ◽  
pp. 613-621 ◽  
Author(s):  
Sriranganathan Varathan ◽  
Satoshi Shibuta ◽  
Vidya Varathan ◽  
Motohide Takemura ◽  
Norifumi Yonehara ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cortical Neurons ◽  
Primary Cultures ◽  
Deep Hypothermia

scholarly journals Structure of the ATP synthase from Mycobacterium smegmatis provides targets for treating tuberculosis

2021 ◽  
Vol 118 (47) ◽  
pp. e2111899118
Author(s):  
Martin G. Montgomery ◽  
Jessica Petri ◽  
Tobias E. Spikes ◽  
John E. Walker
Keyword(s):  
Atp Synthase ◽  
Mycobacterium Smegmatis ◽  
Atp Hydrolysis ◽  
Terminal Region ◽  
Catalytic Cycle ◽  
Α Subunit ◽  
Antitubercular Drugs ◽  
Safe Mechanism ◽  
Fail Safe ◽  
Α Subunits

The structure has been determined by electron cryomicroscopy of the adenosine triphosphate (ATP) synthase from Mycobacterium smegmatis. This analysis confirms features in a prior description of the structure of the enzyme, but it also describes other highly significant attributes not recognized before that are crucial for understanding the mechanism and regulation of the mycobacterial enzyme. First, we resolved not only the three main states in the catalytic cycle described before but also eight substates that portray structural and mechanistic changes occurring during a 360° catalytic cycle. Second, a mechanism of auto-inhibition of ATP hydrolysis involves not only the engagement of the C-terminal region of an α-subunit in a loop in the γ-subunit, as proposed before, but also a “fail-safe” mechanism involving the b′-subunit in the peripheral stalk that enhances engagement. A third unreported characteristic is that the fused bδ-subunit contains a duplicated domain in its N-terminal region where the two copies of the domain participate in similar modes of attachment of the two of three N-terminal regions of the α-subunits. The auto-inhibitory plus the associated “fail-safe” mechanisms and the modes of attachment of the α-subunits provide targets for development of innovative antitubercular drugs. The structure also provides support for an observation made in the bovine ATP synthase that the transmembrane proton-motive force that provides the energy to drive the rotary mechanism is delivered directly and tangentially to the rotor via a Grotthuss water chain in a polar L-shaped tunnel.

scholarly journals Peptide affinity analysis of proteins that bind to an unstructured NH2-terminal region of the osmoprotective transcription factor NFAT5

2016 ◽  
Vol 48 (4) ◽  
pp. 290-305 ◽  
Author(s):  
Jenna F. DuMond ◽  
Kevin Ramkissoon ◽  
Xue Zhang ◽  
Yuichiro Izumi ◽  
Xujing Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Terminal Region ◽  
Hek293 Cells ◽  
The Novel ◽  
Amino Acid Peptide ◽  
Intrinsically Disordered ◽  
Expression Of Genes ◽  
Nuclear Extracts ◽  
And Function ◽  
Peptide Affinity

NFAT5 is an osmoregulated transcription factor that particularly increases expression of genes involved in protection against hypertonicity. Transcription factors often contain unstructured regions that bind co-regulatory proteins that are crucial for their function. The NH2-terminal region of NFAT5 contains regions predicted to be intrinsically disordered. We used peptide aptamer-based affinity chromatography coupled with mass spectrometry to identify protein preys pulled down by one or more overlapping 20 amino acid peptide baits within a predicted NH2-terminal unstructured region of NFAT5. We identify a total of 467 unique protein preys that associate with at least one NH2-terminal peptide bait from NFAT5 in either cytoplasmic or nuclear extracts from HEK293 cells treated with elevated, normal, or reduced NaCl concentrations. Different sets of proteins are pulled down from nuclear vs. cytoplasmic extracts. We used GeneCards to ascertain known functions of the protein preys. The protein preys include many that were previously known, but also many novel ones. Consideration of the novel ones suggests many aspects of NFAT5 regulation, interaction and function that were not previously appreciated, for example, hypertonicity inhibits NFAT5 by sumoylating it and the NFAT5 protein preys include components of the CHTOP complex that desumoylate proteins, an action that should contribute to activation of NFAT5.

scholarly journals Excitotoxic glutamate causes neuronal insulin resistance by inhibiting insulin receptor/Akt/mTOR pathway

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Igor Pomytkin ◽  
Irina Krasil’nikova ◽  
Zanda Bakaeva ◽  
Alexander Surin ◽  
Vsevolod Pinelis
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Cortical Neurons ◽  
Glycogen Synthase ◽  
Primary Cultures ◽  
Biological Response ◽  
Mtor Pathway ◽  
Serine Phosphorylation ◽  
Glutamate Excitotoxicity ◽  
Neuronal Insulin Resistance

Abstract Aim An impaired biological response to insulin in the brain, known as central insulin resistance, was identified during stroke and traumatic brain injury, for which glutamate excitotoxicity is a common pathogenic factor. The exact molecular link between excitotoxicity and central insulin resistance remains unclear. To explore this issue, the present study aimed to investigate the effects of glutamate-evoked increases in intracellular free Ca2+ concentrations [Ca2+]i and mitochondrial depolarisations, two key factors associated with excitotoxicity, on the insulin-induced activation of the insulin receptor (IR) and components of the Akt/ mammalian target of rapamycin (mTOR) pathway in primary cultures of rat cortical neurons. Methods Changes in [Ca2+]i and mitochondrial inner membrane potentials (ΔΨm) were monitored in rat cultured cortical neurons, using the fluorescent indicators Fura-FF and Rhodamine 123, respectively. The levels of active, phosphorylated signalling molecules associated with the IR/Akt/mTOR pathway were measured with the multiplex fluorescent immunoassay. Results When significant mitochondrial depolarisations occurred due to glutamate-evoked massive influxes of Ca2+ into the cells, insulin induced 48% less activation of the IR (assessed by IR tyrosine phosphorylation, pY1150/1151), 72% less activation of Akt (assessed by Akt serine phosphorylation, pS473), 44% less activation of mTOR (assessed by mTOR pS2448), and 38% less inhibition of glycogen synthase kinase β (GSK3β) (assessed by GSK3β pS9) compared with respective controls. These results suggested that excitotoxic glutamate inhibits signalling via the IR/Akt/mTOR pathway at multiple levels, including the IR, resulting in the development of acute neuronal insulin resistance within minutes, as an early pathological event associated with excitotoxicity.

scholarly journals Analysis of Multiquantal Transmitter Release From Single Cultured Cortical Neuron Terminals

1999 ◽  
Vol 81 (4) ◽  
pp. 1810-1817 ◽  
Author(s):  
Oliver Prange ◽  
Timothy H. Murphy
Keyword(s):  
Cortical Neuron ◽  
Cortical Neurons ◽  
Transmitter Release ◽  
Primary Cultures ◽  
Three Dimensional ◽  
Variable Number ◽  
Release Process ◽  
Release Probability ◽  
Synaptic Terminals ◽  
Neuron Terminals

Analysis of multiquantal transmitter release from single cultured cortical neuron terminals. Application of single synapse recording methods indicates that the amplitude of postsynaptic responses of single CNS synapses can vary greatly among repeated stimuli. To determine whether this observation could be attributed to synapses releasing a variable number of transmitter quanta, we assessed the prevalence of multiquantal transmitter release in primary cultures of cortical neurons with the action potential (AP)-dependent presynaptic turnover of the styryl dye FM1–43 ( Betz and Bewick 1992 , 1993 ; Betz et al. 1996 ). It was assumed that if a high proportion of vesicles within a terminal were loaded with FM1–43 the amount of dye released per stimulus would be proportional to the number of quanta released and/or the probability of release at a terminal. To rule out differences in the amount of release (between terminals) caused by release probability or incomplete loading of terminals, conditions were chosen to maximize both release probability and terminal loading. Three-dimensional reconstruction of terminals was employed to ensure that bouton fluorescence was accurately measured. Analysis of the relationship between the loading of terminals and release indicated that presumed larger terminals (>FM1–43 uptake) release a greater amount of dye per stimulus than smaller terminals, suggesting multiquantal release. The distribution of release amounts across terminals was significantly skewed toward higher values, with 13–17% of synaptic terminals apparently releasing multiple quanta per AP. In conclusion, our data suggest that most synaptic terminals release a relatively constant amount of transmitter per stimulus; however, a subset of terminals releases amounts of FM1–43 that are greater than that expected from a unimodal release process.

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