scholarly journals Expression of Kir2.1 Inward Rectifying Potassium Channels in Optic Nerve Glia: Evidence for Heteromeric Association with Kir4.1 and Kir5.1

Neuroglia ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 176-187 ◽  
Author(s):  
Csilla Brasko ◽  
Arthur Butt
Keyword(s):  
Optic Nerve ◽  
Potential Role ◽  
Large Family ◽  
Knock Out ◽  
Kir Channels ◽  
Spatial Buffering ◽  
Knock Out Mice ◽  
Sites Of Action ◽  
The Brain ◽  
Heteromeric Association

Inward rectifying potassium (Kir) channels comprise a large family with diverse biophysical properties. A predominant feature of central nervous system (CNS) glia is their expression of Kir4.1, which as homomers are weakly rectifying channels, but form strongly rectifying channels as heteromers with Kir2.1. However, the extent of Kir2.1 expression and their association with Kir4.1 in glia throughout the CNS is unclear. We have examined this in astrocytes and oligodendrocytes of the mouse optic nerve, a typical CNS white matter tract. Western blot and immunocytochemistry demonstrates that optic nerve astrocytes and oligodendrocytes express Kir2.1 and that it co-localises with Kir4.1. Co-immunoprecipitation analysis provided further evidence that Kir2.1 associate with Kir4.1 and, moreover, Kir2.1 expression was significantly reduced in optic nerves and brains from Kir4.1 knock-out mice. In addition, optic nerve glia express Kir5.1, which may associate with Kir2.1 to form silent channels. Immunocytochemical and co-immunoprecipitation analyses indicate that Kir2.1 associate with Kir5.1 in optic nerve glia, but not in the brain. The results provide evidence that astrocytes and oligodendrocytes may express heteromeric Kir2.1/Kir4.1 and Kir2.1/Kir5.1 channels, together with homomeric Kir2.1 and Kir4.1 channels. In astrocytes, expression of multiple Kir channels is the biophysical substrate for the uptake and redistribution of K+ released during neuronal electrical activity known as ‘potassium spatial buffering’. Our findings suggest a similar potential role for the diverse Kir channels expressed by oligodendrocytes, which by way of their myelin sheaths are intimately associated with the sites of action potential propagation and axonal K+ release.

Levels of d-serine in the brain and peripheral organs of serine racemase (Srr) knock-out mice

2011 ◽  
Vol 59 (6) ◽  
pp. 853-859 ◽  
Author(s):  
Mao Horio ◽  
Mami Kohno ◽  
Yuko Fujita ◽  
Tamaki Ishima ◽  
Ran Inoue ◽  
...  
Keyword(s):  
Serine Racemase ◽  
Knock Out ◽  
Peripheral Organs ◽  
Knock Out Mice ◽  
The Brain

scholarly journals The Neomycin Resistance Cassette in the Targeted Allele of Shank3B Knock-Out Mice Has Potential Off-Target Effects to Produce an Unusual Shank3 Isoform

2021 ◽  
Vol 13 ◽  
Author(s):  
Chunmei Jin ◽  
Hyojin Kang ◽  
Taesun Yoo ◽  
Jae Ryun Ryu ◽  
Ye-Eun Yoo ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Full Length ◽  
Chromosome 15 ◽  
Compensatory Response ◽  
Knock Out ◽  
Expression Levels ◽  
Knock Out Mice ◽  
Neomycin Resistance ◽  
The Brain ◽  
Target Effects

Variants of the SH3 and multiple ankyrin repeat domains 3 (SHANK3), which encodes postsynaptic scaffolds, are associated with brain disorders. The targeted alleles in a few Shank3 knock-out (KO) lines contain a neomycin resistance (Neo) cassette, which may perturb the normal expression of neighboring genes; however, this has not been investigated in detail. We previously reported an unexpected increase in the mRNA expression of Shank3 exons 1–12 in the brains of Shank3B KO mice generated by replacing Shank3 exons 13–16 with the Neo cassette. In this study, we confirmed that the increased Shank3 mRNA in Shank3B KO brains produced an unusual ∼60 kDa Shank3 isoform (Shank3-N), which did not properly localize to the synaptic compartment. Functionally, Shank3-N overexpression altered the dendritic spine morphology in cultured neurons. Importantly, Shank3-N expression in Shank3B KO mice was not a compensatory response to a reduction of full-length Shank3 because expression was still detected in the brain after normalizing the level of full-length Shank3. Moreover, in another Shank3 KO line (Shank3 gKO) with a similar Shank3 exonal deletion as that in Shank3B KO mice but without a Neo cassette, the mRNA expression levels of Shank3 exons 1–12 were lower than those of wild-type mice and Shank3-N was not detected in the brain. In addition, the expression levels of genes neighboring Shank3 on chromosome 15 were altered in the striatum of Shank3B KO but not Shank3 gKO mice. These results suggest that the Neo cassette has potential off-target effects in Shank3B KO mice.

scholarly journals Neuron-specific cTag-CLIP reveals cell-specific diversity of functional RNA regulation in the brain

2018 ◽  
Author(s):  
Yuhki Saito ◽  
Yuan Yuan ◽  
Ilana Zucker-Scharff ◽  
John J. Fak ◽  
Yoko Tajima ◽  
...  
Keyword(s):  
Motor Coordination ◽  
Rna Binding ◽  
Synapse Formation ◽  
Rna Binding Proteins ◽  
Cell Types ◽  
Knock Out ◽  
Knock Out Mice ◽  
Cerebellar Purkinje Cells ◽  
The Brain

SUMMARYRNA-binding proteins (RBPs) regulate genetic diversity, but the degree to which they do so in individual cell-types in vivo is unknown. We employed NOVA2 cTag-CLIP to generate functional RBP-RNA maps from single neuronal populations in the mouse brain. Combining cell-type specific data from Nova2-cTag and Nova2 conditional knock-out mice revealed differential NOVA2 regulatory actions (e.g. alternative splicing) on the same transcripts in different neurons, including in cerebellar Purkinje cells, where NOVA2 acts as an essential factor for proper motor coordination and synapse formation. This also led to the discovery of a mechanism by which NOVA2 action leads to different outcomes in different cells on the same transcripts: NOVA2 is able to regulate retained introns, which subsequently serve as scaffolds for another trans-acting splicing factor, PTBP2. Our results describe differential roles and mechanisms by which RBPs mediate RNA diversity in different neurons and consequent functional outcomes within the brain.

scholarly journals Proteomic Identification of Novel Substrates of a Protein Isoaspartyl Methyltransferase Repair Enzyme

2006 ◽  
Vol 281 (43) ◽  
pp. 32619-32629 ◽  
Author(s):  
Vasanthy Vigneswara ◽  
Jonathan D. Lowenson ◽  
Claire D. Powell ◽  
Matthew Thakur ◽  
Kevin Bailey ◽  
...  
Keyword(s):  
Repair Enzyme ◽  
Knock Out ◽  
Methyl Donor ◽  
Brain Extracts ◽  
Knock Out Mice ◽  
First Time ◽  
The Brain ◽  
Phosphatidylethanolamine Binding Protein ◽  
Mammalian Protein

We report the use of a proteomic strategy to identify hitherto unknown substrates for mammalian protein l-isoaspartate O-methyltransferase. This methyltransferase initiates the repair of isoaspartyl residues in aged or stress-damaged proteins in vivo. Tissues from mice lacking the methyltransferase (Pcmt1-/-) accumulate more isoaspartyl residues than their wild-type littermates, with the most “damaged” residues arising in the brain. To identify the proteins containing these residues, brain homogenates from Pcmt1-/- mice were methylated by exogenous repair enzyme and the radiolabeled methyl donor S-adenosyl-[methyl-3H]methionine. Methylated proteins in the homogenates were resolved by both one-dimensional and two-dimensional electrophoresis, and methyltransferase substrates were identified by their increased radiolabeling when isolated from Pcmt1-/- animals compared with Pcmt1+/+ littermates. Mass spectrometric analyses of these isolated brain proteins reveal for the first time that microtubule-associated protein-2, calreticulin, clathrin light chains a and b, ubiquitin carboxyl-terminal hydrolase L1, phosphatidylethanolamine-binding protein, stathmin, β-synuclein, and α-synuclein, are all substrates for the l-isoaspartate methyltransferase in vivo. Our methodology for methyltransferase substrate identification was further supplemented by demonstrating that one of these methyltransferase targets, microtubule-associated protein-2, could be radiolabeled within Pcmt1-/- brain extracts using radioactive methyl donor and exogenous methyltransferase enzyme and then specifically immunoprecipitated with microtubule-associated protein-2 antibodies to recover co-localized protein with radioactivity. We comment on the functional significance of accumulation of relatively high levels of isoaspartate within these methyltransferase targets in the context of the histological and phenotypical changes associated with the methyltransferase knock-out mice.

Altered regulation of the 5-HT system in the brain of MAO-A knock-out mice

2002 ◽  
Vol 15 (5) ◽  
pp. 841-851 ◽  
Author(s):  
A. Evrard ◽  
I. Malagié ◽  
A.-M. Laporte ◽  
C. Boni ◽  
N. Hanoun ◽  
...  
Keyword(s):  
Knock Out ◽  
Mao A ◽  
Altered Regulation ◽  
Knock Out Mice ◽  
The Brain

scholarly journals Calpain-1 and Calpain-2 in the Brain: New Evidence for a Critical Role of Calpain-2 in Neuronal Death

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2698
Author(s):  
Yubin Wang ◽  
Yan Liu ◽  
Xiaoning Bi ◽  
Michel Baudry
Keyword(s):  
Synaptic Plasticity ◽  
Critical Role ◽  
Protein Targets ◽  
Knock Out ◽  
Regulatory Pathways ◽  
Calcium Dependent ◽  
Binding Domains ◽  
Calpain 2 ◽  
Knock Out Mice ◽  
The Brain

Calpains are a family of soluble calcium-dependent proteases that are involved in multiple regulatory pathways. Our laboratory has focused on the understanding of the functions of two ubiquitous calpain isoforms, calpain-1 and calpain-2, in the brain. Results obtained over the last 30 years led to the remarkable conclusion that these two calpain isoforms exhibit opposite functions in the brain. Calpain-1 activation is required for certain forms of synaptic plasticity and corresponding types of learning and memory, while calpain-2 activation limits the extent of plasticity and learning. Calpain-1 is neuroprotective both during postnatal development and in adulthood, while calpain-2 is neurodegenerative. Several key protein targets participating in these opposite functions have been identified and linked to known pathways involved in synaptic plasticity and neuroprotection/neurodegeneration. We have proposed the hypothesis that the existence of different PDZ (PSD-95, DLG and ZO-1) binding domains in the C-terminal of calpain-1 and calpain-2 is responsible for their association with different signaling pathways and thereby their different functions. Results with calpain-2 knock-out mice or with mice treated with a selective calpain-2 inhibitor indicate that calpain-2 is a potential therapeutic target in various forms of neurodegeneration, including traumatic brain injury and repeated concussions.

scholarly journals Analysis of SUMO1-conjugation at synapses

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
James A Daniel ◽  
Benjamin H Cooper ◽  
Jorma J Palvimo ◽  
Fu-Ping Zhang ◽  
Nils Brose ◽  
...  
Keyword(s):  
Synaptic Proteins ◽  
Wild Type ◽  
Knock Out ◽  
Reporter Mouse ◽  
Neuronal Synapses ◽  
Published Evidence ◽  
Knock Out Mice ◽  
The Brain ◽  
Experimental Strategies ◽  
Genetic Mouse Models

SUMO1-conjugation of proteins at neuronal synapses is considered to be a major post-translational regulatory process in nerve cell and synapse function, but the published evidence for SUMO1-conjugation at synapses is contradictory. We employed multiple genetic mouse models for stringently controlled biochemical and immunostaining analyses of synaptic SUMO1-conjugation. By using a knock-in reporter mouse line expressing tagged SUMO1, we could not detect SUMO1-conjugation of seven previously proposed synaptic SUMO1-targets in the brain. Further, immunostaining of cultured neurons from wild-type and SUMO1 knock-out mice showed that anti-SUMO1 immunolabelling at synapses is non-specific. Our findings indicate that SUMO1-conjugation of synaptic proteins does not occur or is extremely rare and hence not detectable using current methodology. Based on our data, we discuss a set of experimental strategies and minimal consensus criteria for the validation of SUMOylation that can be applied to any SUMOylation substrate and SUMO isoform.

scholarly journals The structure of Neurexin 1α (n1α) and its role as synaptic organizer

Bionatura ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 883-886
Author(s):  
Marjorie Zambonino ◽  
Pamela Pereira
Keyword(s):  
Protein Complexes ◽  
Autism Spectrum ◽  
Knock Out ◽  
Adhesion Protein ◽  
Neuropsychiatric Diseases ◽  
Transmission Of Information ◽  
Complex Protein ◽  
Spectrum Disorders ◽  
Knock Out Mice ◽  
The Brain

α - and b-neurexins (NRXNs) are transmembrane adhesion protein complexes localized in presynaptic membranes into neurons and interact with the postsynaptic neuroligins (NLGNs). Our findings indicate that the neurexin 1α (n1α) is a synaptic organizer that directs postsynaptic development in neurons, evidenced in GABAergic neurons and trials with Knock-out Mice. Also, the interactions between hypervariable surfaces of n1α and ligands (neurexophilin, a-dystroglycan, and GABAA) promotes a proper protein-binding recognition, and consequently, a better synaptic adhesion. There is a direct relationship between mental disorders and the n1α assemblage because NRXN1 gene encodes for n1α proteins which are involved in the transmission of information into the brain. For this reason, damage in this complex-protein or some neurexin gene variations causes pathological abnormalities and neuropsychiatric diseases such as schizophrenia, autism spectrum disorders, and intellectual disabilities.

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