scholarly journals Broad Influence of Mutant Ataxin-3 on the Proteome of the Adult Brain, Young Neurons, and Axons Reveals Central Molecular Processes and Biomarkers in SCA3/MJD Using Knock-In Mouse Model

2021 ◽  
Vol 14 ◽  
Author(s):  
Kalina Wiatr ◽  
Łukasz Marczak ◽  
Jean-Baptiste Pérot ◽  
Emmanuel Brouillet ◽  
Julien Flament ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Disease Progression ◽  
Rna Binding ◽  
Brain Magnetic Resonance Imaging ◽  
Adult Brain ◽  
Spinocerebellar Ataxia Type ◽  
Cellular Transport ◽  
Cerebellar Neurons ◽  
Protein Synthesis Machinery ◽  
The Brain

Spinocerebellar ataxia type 3 (SCA3/MJD) is caused by CAG expansion mutation resulting in a long polyQ domain in mutant ataxin-3. The mutant protein is a special type of protease, deubiquitinase, which may indicate its prominent impact on the regulation of cellular proteins levels and activity. Yet, the global model picture of SCA3 disease progression on the protein level, molecular pathways in the brain, and neurons, is largely unknown. Here, we investigated the molecular SCA3 mechanism using an interdisciplinary research paradigm combining behavioral and molecular aspects of SCA3 in the knock-in ki91 model. We used the behavior, brain magnetic resonance imaging (MRI) and brain tissue examination to correlate the disease stages with brain proteomics, precise axonal proteomics, neuronal energy recordings, and labeling of vesicles. We have demonstrated that altered metabolic and mitochondrial proteins in the brain and the lack of weight gain in Ki91 SCA3/MJD mice is reflected by the failure of energy metabolism recorded in neonatal SCA3 cerebellar neurons. We have determined that further, during disease progression, proteins responsible for metabolism, cytoskeletal architecture, vesicular, and axonal transport are disturbed, revealing axons as one of the essential cell compartments in SCA3 pathogenesis. Therefore we focus on SCA3 pathogenesis in axonal and somatodendritic compartments revealing highly increased axonal localization of protein synthesis machinery, including ribosomes, translation factors, and RNA binding proteins, while the level of proteins responsible for cellular transport and mitochondria was decreased. We demonstrate the accumulation of axonal vesicles in neonatal SCA3 cerebellar neurons and increased phosphorylation of SMI-312 positive adult cerebellar axons, which indicate axonal dysfunction in SCA3. In summary, the SCA3 disease mechanism is based on the broad influence of mutant ataxin-3 on the neuronal proteome. Processes central in our SCA3 model include disturbed localization of proteins between axonal and somatodendritic compartment, early neuronal energy deficit, altered neuronal cytoskeletal structure, an overabundance of various components of protein synthesis machinery in axons.

scholarly journals Broad influence of mutant ataxin-3 on the proteome of the adult brain, young neurons, and axons reveals central molecular processes and biomarkers in SCA3/MJD using knock-in mouse model

2021 ◽  
Author(s):  
Kalina Wiatr ◽  
Łukasz Marczak ◽  
Jean-Baptiste Perot ◽  
Emmanuel Brouillet ◽  
Julien Flament ◽  
...  
Keyword(s):  
Disease Progression ◽  
Rna Binding ◽  
Adult Brain ◽  
Energy Deficit ◽  
Spinocerebellar Ataxia Type ◽  
Cellular Transport ◽  
Molecular Processes ◽  
Disease Mechanism ◽  
Cerebellar Neurons ◽  
The Brain

AbstractSpinocerebellar ataxia type 3 (SCA3/MJD) has a polyQ etiology but, the current knowledge on molecular processes and proteins involved in pathogenesis is not sufficient to fully determine the disease mechanism and find drug targets. Proteases and deubiquitinases, such as Ataxin-3, often have a profound impact on other proteins, yet the global model picture of SCA3 disease progression on the protein level, showing the most crucial proteins and pathways in the brain, and neurons, was not investigated previously. Here, we investigated molecular SCA3 mechanism using interdisciplinary research paradigm combining SCA3 knock-in model, behavior, MRI, brain proteomics, precise axonal proteomics, neuronal energy recordings, labeling of vesicles, and inclusions and focusing in axonal compartment. We have demonstrated that altered metabolic and mitochondrial proteins in the brain and the lack of weight gain in Ki91 SCA3/MJD mice is reflected by the failure of energy metabolism recorded in neonatal SCA3 cerebellar neurons. We have determined that further, during disease progression, proteins responsible for metabolism, cytoskeletal architecture, vesicular and axonal transport proteins are disturbed, revealing axons as one of the essential cell compartments in SCA3 pathogenesis. Therefore we focus on SCA3 pathogenesis in axonal and somatodendritic compartments revealing highly increased axonal localization of protein synthesis machinery, including ribosomes, translation factors, and RNA binding proteins, while the level of proteins responsible for cellular transport, and mitochondria was decreased. We demonstrate the accumulation of axonal vesicles in neonatal SCA3 cerebellar neurons and increased phosphorylation of SMI-312 positive adult cerebellar axons, which indicate axonal dysfunction in SCA3. In summary, the SCA3 disease mechanism is based on the broad influence of mutant ataxin-3 on the neuronal proteome. Processes central in our SCA3 model include disturbed localization of proteins between axonal and somatodendritic compartment, early neuronal energy deficit, altered neuronal cytoskeletal structure, an overabundance of protein synthetic machinery in axons.

scholarly journals Characterizing the nuclear and cytoplasmic transcriptomes in developing and mature human cortex uncovers new insight into psychiatric disease gene regulation

2019 ◽  
Author(s):  
Amanda J. Price ◽  
Taeyoung Hwang ◽  
Ran Tao ◽  
Emily E. Burke ◽  
Anandita Rajpurohi ◽  
...  
Keyword(s):  
Brain Development ◽  
Rna Binding ◽  
Regulation Of Gene Expression ◽  
Adult Brain ◽  
Developmental Expression ◽  
Psychiatric Disease ◽  
Nuclear Pore ◽  
Nuclear Retention ◽  
Gene Sets ◽  
The Brain

AbstractTranscriptome compartmentalization by the nuclear membrane provides both stochastic and functional buffering of transcript activity in the cytoplasm and has recently been implicated in neurodegenerative disease processes. Although many mechanisms regulating transcript compartmentalization are also prevalent in brain development, the extent to which subcellular localization differs as the brain matures has yet to be addressed. To characterize the nuclear and cytoplasmic transcriptomes during brain development, we sequenced both RNA fractions from homogenate prenatal and adult human postmortem cortex using PolyA+ and RiboZero library preparation methods. We find that while many genes are differentially expressed by fraction and developmental expression changes are similarly detectable in nuclear and cytoplasmic RNA, the compartmented transcriptomes become more distinct as the brain matures, perhaps reflecting increased utilization of nuclear retention as a regulatory strategy in adult brain. We examined potential mechanisms of this developmental divergence including alternative splicing, RNA editing, nuclear pore composition, RNA binding protein motif enrichment, and RNA secondary structure. Intron retention is associated with greater nuclear abundance in a subset of transcripts, as is enrichment for several splicing factor binding motifs. Finally, we examined disease association with fraction-regulated gene sets and found nuclear-enriched genes were also preferentially enriched in gene sets associated with neurodevelopmental psychiatric diseases. These results suggest that although gene-level expression is globally comparable between fractions, nuclear retention of transcripts may play an underappreciated role in developmental regulation of gene expression in brain, particularly in genes whose dysregulation is related to neuropsychiatric disorders.

Lessons from the Mouse Model

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. SCI-35-SCI-35
Author(s):  
Johanna M. Rommens ◽  
Marina E. Tourlakis ◽  
Holly Liu ◽  
Rikesh Gandhi ◽  
Peter R. Durie
Keyword(s):  
Protein Synthesis ◽  
Conflicts Of Interest ◽  
Perinatal Death ◽  
Fetal Liver ◽  
Ribosomal Subunit ◽  
Growth Impairment ◽  
Protein Synthesis Machinery ◽  
P53 Activation ◽  
Subunit Joining ◽  
The Brain

Abstract Shwachman-Diamond syndrome (SDS) is a member of the growing list of inherited diseases that result from mutations in genes that encode components of the protein synthesis machinery. Collectively referred to as ribosomopathies, these diseases have selective organ involvement and serious hematological issues with increased susceptibility to malignancy. SDS is caused by mutations in the highly conserved SBDS gene. Recent studies have implicated SBDS in facilitating ribosomal subunit joining for translation initiation. We study mouse models with disease-associated alleles to determine the consequences of loss of Sbds and gain insight into ribosomopathy phenotypes. Mice that are homozygous for a disease-associated allele (SbdsR126T/R126T) die at birth. Growth issues and developmental delay are evident in mid-to-late-stage embryos, and analysis of ribosome profiles indicate disturbed protein synthesis in all tissues examined. SDS-related pathologies in the fetal liver, bone, and brain are also observed. For example, flow cytometry analyses and culturing of fetal liver cells show growth impairment of myeloid lineage progenitors. Ossification is delayed in the developing phalanges. Poor proliferation is evident in early neurons and death due to apoptosis occurs in differentiating neurons, as early as E14.5. As with the brain, the fetal spleen also shows disproportionate growth restriction. These responses reflect varying underlying molecular pathways that hinge on p53 activation. Breeding to Trp53 (p53) deficient mice attenuates the SDS phenotypes but does not rescue the overall growth impairment or the perinatal death. Loss of Sbds leads to a range of organ responses, with engagement of stress pathways at different times and stages. As the severity of the organ pathology does not correlate directly with alteration of 80S or polysome component peak levels in ribosome profiles, we conclude that the organ phenotype reflects limitations in gene expression and timing of expression, or results from disturbed regulation that is specific to cell type and respective protein synthesis demand. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The biological significance of brain barrier mechanisms: help or hindrance in drug delivery to the central nervous system?

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 313 ◽  
Author(s):  
Norman R. Saunders ◽  
Mark D. Habgood ◽  
Kjeld Møllgård ◽  
Katarzyna M. Dziegielewska
Keyword(s):  
Blood Brain Barrier ◽  
Biological Significance ◽  
The Body ◽  
Adult Brain ◽  
Brain Barrier ◽  
Cellular Transport ◽  
Internal Environment ◽  
Blood Brain ◽  
Wide Range ◽  
The Brain

Barrier mechanisms in the brain are important for its normal functioning and development. Stability of the brain’s internal environment, particularly with respect to its ionic composition, is a prerequisite for the fundamental basis of its function, namely transmission of nerve impulses. In addition, the appropriate and controlled supply of a wide range of nutrients such as glucose, amino acids, monocarboxylates, and vitamins is also essential for normal development and function. These are all cellular functions across the interfaces that separate the brain from the rest of the internal environment of the body. An essential morphological component of all but one of the barriers is the presence of specialized intercellular tight junctions between the cells comprising the interface: endothelial cells in the blood-brain barrier itself, cells of the arachnoid membrane, choroid plexus epithelial cells, and tanycytes (specialized glial cells) in the circumventricular organs. In the ependyma lining the cerebral ventricles in the adult brain, the cells are joined by gap junctions, which are not restrictive for intercellular movement of molecules. But in the developing brain, the forerunners of these cells form the neuroepithelium, which restricts exchange of all but the smallest molecules between cerebrospinal fluid and brain interstitial fluid because of the presence of strap junctions between the cells. The intercellular junctions in all these interfaces are the physical basis for their barrier properties. In the blood-brain barrier proper, this is combined with a paucity of vesicular transport that is a characteristic of other vascular beds. Without such a diffusional restrain, the cellular transport mechanisms in the barrier interfaces would be ineffective. Superimposed on these physical structures are physiological mechanisms as the cells of the interfaces contain various metabolic transporters and efflux pumps, often ATP-binding cassette (ABC) transporters, that provide an important component of the barrier functions by either preventing entry of or expelling numerous molecules including toxins, drugs, and other xenobiotics.In this review, we summarize these influx and efflux mechanisms in normal developing and adult brain, as well as indicating their likely involvement in a wide range of neuropathologies.There have been extensive attempts to overcome the barrier mechanisms that prevent the entry of many drugs of therapeutic potential into the brain. We outline those that have been tried and discuss why they may so far have been largely unsuccessful. Currently, a promising approach appears to be focal, reversible disruption of the blood-brain barrier using focused ultrasound, but more work is required to evaluate the method before it can be tried in patients. Overall, our view is that much more fundamental knowledge of barrier mechanisms and development of new experimental methods will be required before drug targeting to the brain is likely to be a successful endeavor. In addition, such studies, if applied to brain pathologies such as stroke, trauma, or multiple sclerosis, will aid in defining the contribution of brain barrier pathology to these conditions, either causative or secondary.

scholarly journals An architectonic type principle in the development of laminar patterns of cortico-cortical connections

2021 ◽  
Author(s):  
Sarah F. Beul ◽  
Alexandros Goulas ◽  
Claus C. Hilgetag
Keyword(s):  
Structural Connectivity ◽  
Macaque Monkey ◽  
Brain Regions ◽  
Adult Brain ◽  
Mammalian Brain ◽  
Cortical Connections ◽  
Cortical Projections ◽  
Structural Connections ◽  
High Degree ◽  
The Brain

AbstractStructural connections between cortical areas form an intricate network with a high degree of specificity. Many aspects of this complex network organization in the adult mammalian cortex are captured by an architectonic type principle, which relates structural connections to the architectonic differentiation of brain regions. In particular, the laminar patterns of projection origins are a prominent feature of structural connections that varies in a graded manner with the relative architectonic differentiation of connected areas in the adult brain. Here we show that the architectonic type principle is already apparent for the laminar origins of cortico-cortical projections in the immature cortex of the macaque monkey. We find that prenatal and neonatal laminar patterns correlate with cortical architectonic differentiation, and that the relation of laminar patterns to architectonic differences between connected areas is not substantially altered by the complete loss of visual input. Moreover, we find that the degree of change in laminar patterns that projections undergo during development varies in proportion to the relative architectonic differentiation of the connected areas. Hence, it appears that initial biases in laminar projection patterns become progressively strengthened by later developmental processes. These findings suggest that early neurogenetic processes during the formation of the brain are sufficient to establish the characteristic laminar projection patterns. This conclusion is in line with previously suggested mechanistic explanations underlying the emergence of the architectonic type principle and provides further constraints for exploring the fundamental factors that shape structural connectivity in the mammalian brain.

scholarly journals Transmembrane receptor DCC associates with protein synthesis machinery and regulates translation

Cell ◽  
2021 ◽  
Vol 184 (9) ◽  
pp. 2520
Author(s):  
Joseph Tcherkezian ◽  
Perry A. Brittis ◽  
Franziska Thomas ◽  
Philippe P. Roux ◽  
John G. Flanagan
Keyword(s):  
Protein Synthesis ◽  
Protein Synthesis Machinery

scholarly journals Transfer of rhodamine-123 into the brain and cerebrospinal fluid of fetal, neonatal and adult rats

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Liam M. Koehn ◽  
Katarzyna M. Dziegielewska ◽  
Mark D. Habgood ◽  
Yifan Huang ◽  
Norman R. Saunders
Keyword(s):  
Cerebrospinal Fluid ◽  
Fetal Brain ◽  
Maternal Blood ◽  
Adult Brain ◽  
Rhodamine 123 ◽  
Patient Specific ◽  
Adult Rats ◽  
Blood Brain ◽  
The Brain ◽  
Brain Barriers

Abstract Background Adenosine triphosphate binding cassette transporters such as P-glycoprotein (PGP) play an important role in drug pharmacokinetics by actively effluxing their substrates at barrier interfaces, including the blood-brain, blood-cerebrospinal fluid (CSF) and placental barriers. For a molecule to access the brain during fetal stages it must bypass efflux transporters at both the placental barrier and brain barriers themselves. Following birth, placental protection is no longer present and brain barriers remain the major line of defense. Understanding developmental differences that exist in the transfer of PGP substrates into the brain is important for ensuring that medication regimes are safe and appropriate for all patients. Methods In the present study PGP substrate rhodamine-123 (R123) was injected intraperitoneally into E19 dams, postnatal (P4, P14) and adult rats. Naturally fluorescent properties of R123 were utilized to measure its concentration in blood-plasma, CSF and brain by spectrofluorimetry (Clariostar). Statistical differences in R123 transfer (concentration ratios between tissue and plasma ratios) were determined using Kruskal-Wallis tests with Dunn’s corrections. Results Following maternal injection the transfer of R123 across the E19 placenta from maternal blood to fetal blood was around 20 %. Of the R123 that reached fetal circulation 43 % transferred into brain and 38 % into CSF. The transfer of R123 from blood to brain and CSF was lower in postnatal pups and decreased with age (brain: 43 % at P4, 22 % at P14 and 9 % in adults; CSF: 8 % at P4, 8 % at P14 and 1 % in adults). Transfer from maternal blood across placental and brain barriers into fetal brain was approximately 9 %, similar to the transfer across adult blood-brain barriers (also 9 %). Following birth when placental protection was no longer present, transfer of R123 from blood into the newborn brain was significantly higher than into adult brain (3 fold, p < 0.05). Conclusions Administration of a PGP substrate to infant rats resulted in a higher transfer into the brain than equivalent doses at later stages of life or equivalent maternal doses during gestation. Toxicological testing of PGP substrate drugs should consider the possibility of these patient specific differences in safety analysis.

scholarly journals Functional Role of Tia1/Pub1 and Sup35 Prion Domains: Directing Protein Synthesis Machinery to the Tubulin Cytoskeleton

2014 ◽  
Vol 55 (2) ◽  
pp. 305-318 ◽  
Author(s):  
Xiang Li ◽  
Joseph B. Rayman ◽  
Eric R. Kandel ◽  
Irina L. Derkatch
Keyword(s):  
Protein Synthesis ◽  
Functional Role ◽  
Protein Synthesis Machinery

The novel guanylyl cyclase MsGC-I is strongly expressed in higher-order neuropils in the brain of Manduca sexta

2001 ◽  
Vol 204 (2) ◽  
pp. 305-314 ◽  
Author(s):  
A. Nighorn ◽  
P.J. Simpson ◽  
D.B. Morton
Keyword(s):  
Nervous System ◽  
Manduca Sexta ◽  
Guanylyl Cyclase ◽  
Higher Order ◽  
Adult Brain ◽  
Central Complex ◽  
Amino Acid Residues ◽  
Order Processing ◽  
Guanylyl Cyclases ◽  
The Brain

Guanylyl cyclases are usually characterized as being either soluble (sGCs) or receptor (rGCs). We have recently cloned a novel guanylyl cyclase, MsGC-I, from the developing nervous system of the hawkmoth Manduca sexta that cannot be classified as either an sGC or an rGC. MsGC-I shows highest sequence identity with receptor guanylyl cyclases throughout its catalytic and dimerization domains, but does not contain the ligand-binding, transmembrane or kinase-like domains characteristic of receptor guanylyl cyclases. In addition, MsGC-I contains a C-terminal extension of 149 amino acid residues. In this paper, we report the expression of MsGC-I in the adult. Northern blots show that it is expressed preferentially in the nervous system, with high levels in the pharate adult brain and antennae. In the antennae, immunohistochemical analyses show that it is expressed in the cell bodies and dendrites, but not axons, of olfactory receptor neurons. In the brain, it is expressed in a variety of sensory neuropils including the antennal and optic lobes. It is also expressed in structures involved in higher-order processing including the mushroom bodies and central complex. This complicated expression pattern suggests that this novel guanylyl cyclase plays an important role in mediating cyclic GMP levels in the nervous system of Manduca sexta.

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