ABSTRACT
The expression of Neuritin-1 (NRN1), a neurotrophic factor crucial for neurodevelopment and synaptic plasticity, is enhanced by the Brain Derived Neurotrophic Factor (BDNF). Although the receptor of NRN1 remains unclear, it is suggested that NRN1's activation of the insulin receptor (IR) pathway promotes the transcription of the calcium voltage-gated channel subunit alpha1 C (CACNA1C). These three genes have been independently associated with schizophrenia (SZ) risk, symptomatology, and brain differences. However, research on how they synergistically modulate these phenotypes is scarce. We aimed to study whether the genetic epistasis between these genes affects the risk and clinical presentation of the disorder via its effect on brain structure. First, we tested the epistatic effect of NRN1 and BDNF or CACNA1C on (i) the risk for SZ, (ii) clinical symptoms severity and functionality (onset, PANSS, CGI and GAF), and (iii) brain cortical structure (thickness, surface area and volume measures estimated using FreeSurfer) in a sample of 86 SZ patients and 89 healthy subjects. Second, we explored whether those brain clusters influenced by epistatic effects mediate the clinical profiles. Although we did not find a direct epistatic impact on the risk, our data unveiled significant effects on the disorder's clinical presentation. Specifically, the NRN1-rs10484320 x BDNF-rs6265 interplay influenced PANSS general psychopathology, and the NRN1-rs4960155 x CACNA1C-rs1006737 interaction affected GAF scores. Moreover, several interactions between NRN1 SNPs and BDNF-rs6265 significantly influenced the surface area and cortical volume of the frontal, parietal, and temporal brain regions within patients. The NRN1-rs10484320 x BDNF-rs6265 epistasis in the left lateral orbitofrontal cortex fully mediated the effect on PANSS general psychopathology. Our study not only adds clinical significance to the well-described molecular relationship between NRN1 and BDNF but also underscores the utility of deconstructing SZ into biologically validated brain-imaging markers to explore their mediation role in the path from genetics to complex clinical manifestation.
Subject(s)
Brain-Derived Neurotrophic Factor , Calcium Channels, L-Type , Epistasis, Genetic , Schizophrenia , Humans , Brain-Derived Neurotrophic Factor/genetics , Schizophrenia/genetics , Schizophrenia/pathology , Female , Male , Adult , Calcium Channels, L-Type/genetics , Middle Aged , Brain/pathology , Polymorphism, Single Nucleotide , Neuropeptides/genetics , Neuropeptides/metabolism , Magnetic Resonance Imaging , Young Adult , GPI-Linked ProteinsABSTRACT
Alternative RNA splicing is an essential and dynamic process in neuronal differentiation and synapse maturation, and dysregulation of this process has been associated with neurodegenerative diseases. Recent studies have revealed the importance of RNA-binding proteins in the regulation of neuronal splicing programs. However, the molecular mechanisms involved in the control of these splicing regulators are still unclear. Here, we show that KIS, a kinase upregulated in the developmental brain, imposes a genome-wide alteration in exon usage during neuronal differentiation in mice. KIS contains a protein-recognition domain common to spliceosomal components and phosphorylates PTBP2, counteracting the role of this splicing factor in exon exclusion. At the molecular level, phosphorylation of unstructured domains within PTBP2 causes its dissociation from two co-regulators, Matrin3 and hnRNPM, and hinders the RNA-binding capability of the complex. Furthermore, KIS and PTBP2 display strong and opposing functional interactions in synaptic spine emergence and maturation. Taken together, our data uncover a post-translational control of splicing regulators that link transcriptional and alternative exon usage programs in neuronal development.
Subject(s)
Alternative Splicing , Exons , Neurons , Polypyrimidine Tract-Binding Protein , Protein Serine-Threonine Kinases , Animals , Humans , Mice , Exons/genetics , Heterogeneous-Nuclear Ribonucleoproteins/metabolism , Heterogeneous-Nuclear Ribonucleoproteins/genetics , Nerve Tissue Proteins/metabolism , Nerve Tissue Proteins/genetics , Neurons/metabolism , Phosphorylation , Polypyrimidine Tract-Binding Protein/metabolism , Polypyrimidine Tract-Binding Protein/genetics , RNA-Binding Proteins/metabolism , RNA-Binding Proteins/genetics , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolismABSTRACT
Included in the neurotrophins family, the Neuritin 1 gene (NRN1) has emerged as an attractive candidate gene for schizophrenia (SZ) since it has been associated with the risk for the disorder and general cognitive performance. In this work, we aimed to further investigate the association of NRN1 with SZ by exploring its role on age at onset and its brain activity correlates. First, we developed two genetic association analyses using a family-based sample (80 early-onset (EO) trios (offspring onset ≤ 18 years) and 71 adult-onset (AO) trios) and an independent case-control sample (120 healthy subjects (HS), 87 EO and 138 AO patients). Second, we explored the effect of NRN1 on brain activity during a working memory task (N-back task; 39 HS, 39 EO and 39 AO; matched by age, sex and estimated IQ). Different haplotypes encompassing the same three Single Nucleotide Polymorphisms(SNPs, rs3763180-rs10484320-rs4960155) were associated with EO in the two samples (GCT, TCC and GTT). Besides, the GTT haplotype was associated with worse N-back task performance in EO and was linked to an inefficient dorsolateral prefrontal cortex activity in subjects with EO compared to HS. Our results show convergent evidence on the NRN1 association with EO both from genetic and neuroimaging approaches, highlighting the role of neurotrophins in the pathophysiology of SZ.
Subject(s)
GPI-Linked Proteins , Neuropeptides , Schizophrenia , Adult , GPI-Linked Proteins/genetics , Humans , Magnetic Resonance Imaging , Memory, Short-Term/physiology , Nerve Growth Factors/genetics , Neuroimaging , Neuropeptides/genetics , Polymorphism, Single Nucleotide , Prefrontal Cortex , Schizophrenia/diagnosis , Schizophrenia/geneticsABSTRACT
Synaptic plasticity involves structural modifications in dendritic spines that are modulated by local protein synthesis and actin remodeling. Here, we investigated the molecular mechanisms that connect synaptic stimulation to these processes. We found that the phosphorylation of isoform-specific sites in eEF1A2-an essential translation elongation factor in neurons-is a key modulator of structural plasticity in dendritic spines. Expression of a nonphosphorylatable eEF1A2 mutant stimulated mRNA translation but reduced actin dynamics and spine density. By contrast, a phosphomimetic eEF1A2 mutant exhibited decreased association with F-actin and was inactive as a translation elongation factor. Activation of metabotropic glutamate receptor signaling triggered transient dissociation of eEF1A2 from its regulatory guanine exchange factor (GEF) protein in dendritic spines in a phosphorylation-dependent manner. We propose that eEF1A2 establishes a cross-talk mechanism that coordinates translation and actin dynamics during spine remodeling.
Subject(s)
Actins , Dendritic Spines , Peptide Elongation Factor 1/metabolism , Protein Biosynthesis , Actin Cytoskeleton , Actins/genetics , Neuronal Plasticity , NeuronsABSTRACT
Stress granules (SGs) are conserved biomolecular condensates that originate in response to many stress conditions. These membraneless organelles contain nontranslating mRNAs and a diverse subproteome, but our knowledge of their regulation and functional relevance is still incipient. Here, we describe a mutual-inhibition interplay between SGs and Cdc28, the budding yeast Cdk. Among Cdc28 interactors acting as negative modulators of Start, we have identified Whi8, an RNA-binding protein that localizes to SGs and recruits the mRNA of CLN3, the most upstream G1 cyclin, for efficient translation inhibition and Cdk inactivation under stress. However, Whi8 also contributes to recruiting Cdc28 to SGs, where it acts to promote their dissolution. As predicted by a mutual-inhibition framework, the SG constitutes a bistable system that is modulated by Cdk. Since mammalian cells display a homologous mechanism, we propose that the opposing functions of specific mRNA-binding proteins and Cdk's subjugate SG dynamics to a conserved hysteretic switch.
Subject(s)
CDC28 Protein Kinase, S cerevisiae/metabolism , Cytoplasmic Granules/metabolism , Saccharomyces cerevisiae/metabolism , Stress, Physiological , Cell Cycle , Cyclins/metabolism , HeLa Cells , Humans , Intrinsically Disordered Proteins/chemistry , Intrinsically Disordered Proteins/metabolism , Models, Biological , Protein Binding , Protein Biosynthesis , RNA, Messenger/metabolism , Saccharomyces cerevisiae Proteins/metabolismABSTRACT
Regulation of mRNA localization is a conserved cellular process observed in many types of cells and organisms. Asymmetrical mRNA distribution plays a particularly important role in the nervous system, where local translation of localized mRNA represents a key mechanism in synaptic plasticity. CaMKIIα is a very abundant mRNA detected in neurites, consistent with its crucial role at glutamatergic synapses. Here, we report the presence of CaMKIIα mRNA isoforms that contain intron i16 in dendrites, RNA granules, and synaptoneurosomes from primary neurons and brain. This subpopulation of unspliced mRNA preferentially localizes to distal dendrites in a synaptic-activity-dependent manner. Staufen2, a well-established marker of RNA transport in dendrites, interacts with intron i16 sequences and enhances its distal dendritic localization, pointing to the existence of intron-mediated mechanisms in the molecular pathways that modulate dendritic transport and localization of synaptic mRNAs.
Subject(s)
Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism , Dendrites/metabolism , Nerve Tissue Proteins/metabolism , RNA, Messenger/metabolism , RNA-Binding Proteins/metabolism , Animals , Brain/cytology , Brain/metabolism , Calcium-Calmodulin-Dependent Protein Kinase Type 2/genetics , Cells, Cultured , Introns , Mice , Nerve Tissue Proteins/genetics , RNA, Messenger/genetics , RNA-Binding Proteins/genetics , Synapses/metabolismABSTRACT
A precise immune response is essential for cellular homeostasis and animal survival. The paramount importance of its control is reflected by the fact that its non-specific activation leads to inflammatory events that ultimately contribute to the appearance of many chronic diseases. However, the molecular mechanisms preventing non-specific activation and allowing a quick response upon signal activation are not yet fully understood. In this paper we uncover a new function of PHF8 blocking signal independent activation of immune gene promoters. Affinity purifications coupled with mass spectrometry analysis identified SIN3A and HDAC1 corepressors as new PHF8 interacting partners. Further molecular analysis demonstrated that prior to interferon gamma (IFNγ) stimulation, PHF8 is bound to a subset of IFNγ-responsive promoters. Through the association with HDAC1 and SIN3A, PHF8 keeps the promoters in a silent state, maintaining low levels of H4K20me1. Upon IFNγ treatment, PHF8 is phosphorylated by ERK2 and evicted from the promoters, correlating with an increase in H4K20me1 and transcriptional activation. Our data strongly indicate that in addition to its well-characterized function as a coactivator, PHF8 safeguards transcription to allow an accurate immune response.
Subject(s)
Histone Demethylases/metabolism , Interferon-gamma/pharmacology , Transcription Factors/metabolism , Transcriptional Activation , Cell Line , Chromatin/metabolism , Gene Silencing , Histone Deacetylase 1/metabolism , Humans , Mitogen-Activated Protein Kinase 1/metabolism , Promoter Regions, Genetic , Repressor Proteins/metabolism , Sin3 Histone Deacetylase and Corepressor ComplexABSTRACT
TCERG1 is a highly conserved human protein implicated in interactions with the transcriptional and splicing machinery that is associated with neurodegenerative disorders. Biochemical, neuropathological, and genetic evidence suggests an important role for TCERG1 in Huntington's disease (HD) pathogenesis. At present, the molecular mechanism underlying TCERG1-mediated neuronal effects is unknown. Here, we show that TCERG1 depletion led to widespread alterations in mRNA processing that affected different types of alternative transcriptional or splicing events, indicating that TCERG1 plays a broad role in the regulation of alternative splicing. We observed considerable changes in the transcription and alternative splicing patterns of genes involved in cytoskeleton dynamics and neurite outgrowth. Accordingly, TCERG1 depletion in the neuroblastoma SH-SY5Y cell line and primary mouse neurons affected morphogenesis and resulted in reduced dendritic outgrowth, with a major effect on dendrite ramification and branching complexity. These defects could be rescued by ectopic expression of TCERG1. Our results indicate that TCERG1 affects expression of multiple mRNAs involved in neuron projection development, whose misregulation may be involved in TCERG1-linked neurological disorders.
Subject(s)
Cytoskeleton/metabolism , Neuroblastoma/metabolism , Neuronal Outgrowth/physiology , Neurons/metabolism , Transcriptional Elongation Factors/biosynthesis , Alternative Splicing/physiology , Animals , Cell Line, Tumor , Cells, Cultured , Cytoskeleton/genetics , Cytoskeleton/pathology , Female , HEK293 Cells , Humans , Male , Mice , Neuroblastoma/genetics , Neuroblastoma/pathology , Neurons/pathology , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Transcriptional Elongation Factors/deficiency , Transcriptional Elongation Factors/geneticsABSTRACT
Protein tagging is widely used in approaches ranging from affinity purification to fluorescence-based detection in live cells. However, an intrinsic limitation of tagging is that the native function of the protein may be compromised or even abolished by the presence of the tag. Here we describe and characterize a set of small, innocuous protein tags (inntags) that we anticipate will find application in a variety of biological techniques.
Subject(s)
Epitopes/analysis , Epitopes/chemistry , Fluorescent Antibody Technique/methods , Immunoprecipitation/methods , Proteins/analysis , Proteins/immunology , Animals , Antibodies, Monoclonal , Epitopes/genetics , Female , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , HEK293 Cells , Humans , Mice , Mice, Inbred BALB C , NIH 3T3 Cells , Protein Conformation , Protein Structure, Tertiary , Recombinant Proteins/genetics , Recombinant Proteins/metabolismABSTRACT
Local regulation of protein synthesis allows a neuron to rapidly alter the proteome in response to synaptic signals, an essential mechanism in synaptic plasticity that is altered in many neurological diseases. Synthesis of many synaptic proteins is under local control and much of this regulation occurs through structures termed RNA granules. KIS is a protein kinase that associates with stathmin, a modulator of the tubulin cytoskeleton. Furthermore, KIS is found in RNA granules and stimulates translation driven by the ß-actin 3'UTR in neurites. Here we explore the physiological and molecular mechanisms underlying the action of KIS on hippocampal synaptic plasticity in mice. KIS downregulation compromises spine development, alters actin dynamics, and reduces postsynaptic responsiveness. The absence of KIS results in a significant decrease of protein levels of PSD-95, a postsynaptic scaffolding protein, and the AMPAR subunits GluR1 and GluR2 in a CPEB3-dependent manner. Underlying its role in spine maturation, KIS is able to suppress the spine developmental defects caused by CPEB3 overexpression. Moreover, either by direct or indirect mechanisms, KIS counteracts the inhibitory activity of CPEB3 on the GluR2 3'UTR at both mRNA translation and polyadenylation levels. Our study provides insights into the mechanisms that mediate dendritic spine morphogenesis and functional synaptic maturation, and suggests KIS as a link regulating spine cytoskeleton and postsynaptic activity in memory formation.
Subject(s)
Dendritic Spines/metabolism , Intracellular Signaling Peptides and Proteins/physiology , Microtubules/physiology , Neuronal Plasticity/physiology , Protein Biosynthesis/physiology , Protein Serine-Threonine Kinases/physiology , Receptors, AMPA/biosynthesis , Animals , Hippocampus/cytology , Hippocampus/metabolism , Mice , Organ Culture TechniquesABSTRACT
Cells commit to a new cell cycle at Start by activation of the G1 Cdk-cyclin complex which, in turn, triggers a genome-wide transcriptional wave that executes the G1/S transition. In budding yeast, the Cdc28-Cln3 complex is regulated by an ER-retention mechanism that is important for proper cell size control. We have isolated small-cell-size CDC28 mutants showing impaired retention at the ER and premature accumulation of the Cln3 cyclin in the nucleus. The differential interactome of a quintuple Cdc28(wee) mutant pinpointed Whi7, a Whi5 paralog targeted by Cdc28 that associates to the ER in a phosphorylation-dependent manner. Our results demonstrate that the Cln3 cyclin and Whi7 act in a positive feedback loop to release the G1 Cdk-cyclin complex and trigger Start once a critical size has been reached, thus uncovering a key nonlinear mechanism at the earliest known events of cell-cycle entry.
Subject(s)
CDC28 Protein Kinase, S cerevisiae/metabolism , Cyclins/metabolism , Endoplasmic Reticulum/metabolism , G1 Phase/physiology , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/metabolism , CDC28 Protein Kinase, S cerevisiae/genetics , Cyclins/genetics , Endoplasmic Reticulum/genetics , Mutation , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/geneticsABSTRACT
Budding yeast cells are assumed to trigger Start and enter the cell cycle only after they attain a critical size set by external conditions. However, arguing against deterministic models of cell size control, cell volume at Start displays great individual variability even under constant conditions. Here we show that cell size at Start is robustly set at a single-cell level by the volume growth rate in G1, which explains the observed variability. We find that this growth-rate-dependent sizer is intimately hardwired into the Start network and the Ydj1 chaperone is key for setting cell size as a function of the individual growth rate. Mathematical modelling and experimental data indicate that a growth-rate-dependent sizer is sufficient to ensure size homeostasis and, as a remarkable advantage over a rigid sizer mechanism, it reduces noise in G1 length and provides an immediate solution for size adaptation to external conditions at a population level.
Subject(s)
Cell Cycle , Saccharomyces cerevisiae/cytology , Saccharomyces cerevisiae/growth & development , G1 Phase , HSP40 Heat-Shock Proteins/genetics , HSP40 Heat-Shock Proteins/metabolism , Homeostasis , Kinetics , Saccharomyces cerevisiae/chemistry , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolismABSTRACT
PHF8 is a histone demethylase associated with X-linked mental retardation. It has been described as a transcriptional co-activator involved in cell cycle progression, but its physiological role is still poorly understood. Here we show that PHF8 controls the expression of genes involved in cell adhesion and cytoskeleton organization such as RhoA, Rac1 and GSK3ß. A lack of PHF8 not only results in a cell cycle delay but also in a disorganized actin cytoskeleton and impaired cell adhesion. Our data demonstrate that PHF8 directly regulates the expression of these genes by demethylating H4K20me1 at promoters. Moreover, c-Myc transcription factor cooperates with PHF8 to regulate the analysed promoters. Further analysis in neurons shows that depletion of PHF8 results in down-regulation of cytoskeleton genes and leads to a deficient neurite outgrowth. Overall, our results suggest that the mental retardation phenotype associated with loss of function of PHF8 could be due to abnormal neuronal connections as a result of alterations in cytoskeleton function.
Subject(s)
Actin Cytoskeleton/ultrastructure , Gene Expression Regulation , Histone Demethylases/physiology , Transcription Factors/physiology , Transcription, Genetic , Animals , Cell Adhesion/genetics , Cell Line , Cells, Cultured , Down-Regulation , Glycogen Synthase Kinase 3/genetics , Glycogen Synthase Kinase 3 beta , HeLa Cells , Histone Demethylases/antagonists & inhibitors , Humans , Mice , Neurites/ultrastructure , Proto-Oncogene Proteins c-myc/metabolism , Transcription Factors/antagonists & inhibitors , alpha Catenin/genetics , rho GTP-Binding Proteins/genetics , rho GTP-Binding Proteins/metabolismABSTRACT
Nuclear accumulation of cyclin D1 because of altered trafficking or degradation is thought to contribute directly to neoplastic transformation and growth. Mechanisms of cyclin D1 localization in S phase have been studied in detail, but its control during exit from the cell cycle and quiescence is poorly understood. Here we report that translokin (Tlk), a microtubule-associated protein also termed Cep57, interacts with cyclin D1 and controls its nucleocytoplasmic distribution in quiescent cells. Tlk binds to regions of cyclin D1 also involved in binding to cyclin-dependent kinase 4 (Cdk4), and a fraction of cyclin D1 associates to the juxtanuclear Tlk network in the cell. Downregulation of Tlk levels results in undue nuclear accumulation of cyclin D1 and increased Cdk4-dependent phosphorylation of pRB under quiescence conditions. In turn, overexpression of Tlk prevents proper cyclin D1 accumulation in the nucleus of proliferating cells in an interaction-dependent manner, inhibits Cdk4-dependent phosphorylation of pRB and hinders cell cycle progression to S phase. We propose that the Tlk acts as a key negative regulator in the pathway that drives nuclear import of cyclin D1, thus contributing to prevent pRB inactivation and to maintain cellular quiescence.
Subject(s)
Carrier Proteins/metabolism , Cell Cycle/physiology , Cell Nucleus/metabolism , Cyclin D1/metabolism , Fibroblasts/metabolism , Animals , Cell Cycle Proteins , Cells, Cultured , Cyclin-Dependent Kinase 4/metabolism , Fibroblasts/cytology , Humans , Mice , Mice, Knockout , Retinoblastoma Protein/metabolismABSTRACT
E47 is a basic helix-loop-helix transcription factor involved in neuronal differentiation and survival. We had previously shown that the basic helix-loop-helix protein E47 binds to E-box sequences within the promoter of the TrkB gene and activates its transcription. Proper expression of the TrkB receptor plays a key role in development and function of the vertebrate nervous system, and altered levels of TrkB have been associated with important human diseases. Here we show that E47 interacts with MLK2, a mixed lineage kinase (MLK) involved in JNK-mediated activation of programmed cell death. MLK2 enhances phosphorylation of the AD2 activation domain of E47 in vivo in a JNK-independent manner and phosphorylates in vitro defined serine and threonine residues within a loop-helix structure of AD2 that also contains a putative MLK docking site. Although these residues are essential for MLK2-mediated inactivation of E47, inhibition of MLKs by CEP11004 causes up-regulation of TrkB at a transcriptional level in cerebellar granule neurons and differentiating neuroblastoma cells. These findings allow us to propose a novel mechanism by which MLK regulates TrkB expression through phosphorylation of an activation domain of E47. This molecular link would explain why MLK inhibitors not only prevent activation of cell death processes but also enhance cell survival signaling as a key aspect of their neuroprotective potential.
Subject(s)
Gene Expression Regulation, Enzymologic , MAP Kinase Kinase Kinases/metabolism , Neurons/metabolism , Receptor, trkB/biosynthesis , TCF Transcription Factors/physiology , Animals , Cell Death , Cell Line, Tumor , Cell Survival , Dimerization , Humans , Mice , Phosphorylation , TCF Transcription Factors/metabolism , Transcription Factor 7-Like 1 Protein , Transcription, GeneticABSTRACT
In previous studies we have demonstrated that the active form of vitamin D (1,25(OH)(2)D(3)) increases vascular endothelial growth factor (VEGF) expression and release in vascular smooth muscle cells (VSMC) in vitro. However, the mechanism by which 1,25(OH)(2)D(3) increases VEGF production is currently unknown. In this work, we demonstrated binding of vitamin D receptor to two response elements in the VEGF promoter. We performed promoter transactivation analysis and we observed that, in 293T cells, VEGF promoter was activated after vitamin D treatment. Using site-directed mutagenesis we have shown that both response elements are important for VEGF promoter activity. Therefore, the increase in VEGF expression and secretion induced by 1,25(OH)(2)D(3) in VSMC in vitro could be explained by direct binding of the vitamin D receptor, as a transcription factor, to VEGF promoter. These results could explain part of the beneficial effects of vitamin D treatment in renal patients by a possible VEGF-mediated improvement of the endothelial dysfunction.
Subject(s)
Calcitriol/metabolism , Promoter Regions, Genetic , Receptors, Calcitriol/metabolism , Transcriptional Activation , Vascular Endothelial Growth Factor A/metabolism , Base Sequence , Cell Line , Genes, Reporter , Humans , Molecular Sequence Data , Mutagenesis, Site-Directed , Mutation , Transfection , Up-Regulation , Vascular Endothelial Growth Factor A/geneticsABSTRACT
The regulation of mRNA transport is a fundamental process for cytoplasmic sorting of transcripts and spatially controlled translational derepression once properly localized. There is growing evidence that translation is locally modulated as a result of specific synaptic inputs. However, the underlying molecular mechanisms that regulate this translational process are just emerging. We show that KIS, a serine/threonine kinase functionally related to microtubule dynamics and axon development, interacts with three proteins found in RNA granules: KIF3A, NonO, and eEF1A. KIS localizes to RNA granules and colocalizes with the KIF3A kinesin and the beta-actin mRNA in cultured cortical neurons. In addition, KIS is found associated with KIF3A and 10 RNP-transported mRNAs in brain extracts. The results of knockdown experiments indicate that KIS is required for normal neurite outgrowth. More important, the kinase activity of KIS stimulates 3' untranslated region-dependent local translation in neuritic projections. We propose that KIS is a component of the molecular device that modulates translation in RNA-transporting granules as a result of local signals.
Subject(s)
Cytoplasmic Granules/enzymology , Intracellular Signaling Peptides and Proteins/metabolism , Protein Biosynthesis , Protein Serine-Threonine Kinases/metabolism , RNA/metabolism , 3' Untranslated Regions/metabolism , Actins/genetics , Actins/metabolism , Animals , Cell Line , Cerebral Cortex/cytology , Cerebral Cortex/enzymology , Gene Expression Regulation , Humans , Kinesins/metabolism , Mice , Neurites/enzymology , Neurons/cytology , Neurons/enzymology , Protein Binding , Protein Transport , RNA Transport , RNA, Messenger/genetics , RNA, Messenger/metabolism , Ribonucleoproteins/metabolism , Tissue ExtractsABSTRACT
G1 cyclin Cln3 plays a key role in linking cell growth and proliferation in budding yeast. It is generally assumed that Cln3, which is present throughout G1, accumulates passively in the nucleus until a threshold is reached to trigger cell cycle entry. We show here that Cln3 is retained bound to the ER in early G1 cells. ER retention requires binding of Cln3 to the cyclin-dependent kinase Cdc28, a fraction of which also associates to the ER. Cln3 contains a chaperone-regulatory Ji domain that counteracts Ydj1, a J chaperone essential for ER release and nuclear accumulation of Cln3 in late G1. Finally, Ydj1 is limiting for release of Cln3 and timely entry into the cell cycle. As protein synthesis and ribosome assembly rates compromise chaperone availability, we hypothesize that Ydj1 transmits growth capacity information to the cell cycle for setting efficient size/ploidy ratios.
Subject(s)
Cyclins/metabolism , HSP40 Heat-Shock Proteins/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Adenosine Triphosphatases/genetics , Adenosine Triphosphatases/metabolism , Amino Acid Sequence , Cell Cycle , Cell Nucleus/metabolism , Cyclins/chemistry , Cyclins/genetics , Endoplasmic Reticulum/metabolism , G1 Phase , HSP40 Heat-Shock Proteins/genetics , HSP70 Heat-Shock Proteins/genetics , HSP70 Heat-Shock Proteins/metabolism , Models, Molecular , Molecular Sequence Data , Ploidies , Protein Structure, Tertiary , Saccharomyces cerevisiae/cytology , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/chemistry , Saccharomyces cerevisiae Proteins/genetics , Sequence Homology, Amino AcidABSTRACT
Estamos aun lejos de conocer todos los aspectos que rodean a la problemática del dolor en el paciente anciano. La demencia, se está convirtiendo en un síndrome geriátrico cada vez más frecuente dado el progresivo aumento de la supervivencia tanto de la población general como de los enfermos. En las diferentes etapas de la misma demencia las necesidades sociosanitarias son también cambiantes. El dolor en estos pacientes es a menudo un aspecto mal evaluado e infratratado. Las personas con demencia que están institucionalizadas o que ingresan en Hospitales de agudos para tratamiento médico o quirúrgico presentan un alto riesgo de infradetección e infratratamiento o tratamiento subóptimo del dolor. De su evaluación cuidados a puede resultar el mantenimiento o incluso la mejora de algunas de las capacidades preservadas. La evaluación del dolor en el paciente con demencia obliga a una observación minuciosa y a valorar dimensiones relacionadas con la conducta frente a diversas situaciones así como a una utilización juiciosa de los instrumentos de evaluación (AU)
No disponible
Subject(s)
Humans , Dementia/complications , Pain/diagnosis , Pain/drug therapy , Geriatric Assessment/methods , BioethicsABSTRACT
Fas apoptosis inhibitory molecule (FAIM) is a protein identified as an antagonist of Fas-induced cell death. We show that FAIM overexpression fails to rescue neurons from trophic factor deprivation, but exerts a marked neurite growth-promoting action in different neuronal systems. Whereas FAIM overexpression greatly enhanced neurite outgrowth from PC12 cells and sympathetic neurons grown with nerve growth factor (NGF), reduction of endogenous FAIM levels by RNAi decreased neurite outgrowth in these cells. FAIM overexpression promoted NF-kappa B activation, and blocking this activation by using a super-repressor I kappa B alpha or by carrying out experiments using cortical neurons from mice that lack the p65 NF-kappa B subunit prevented FAIM-induced neurite outgrowth. The effect of FAIM on neurite outgrowth was also blocked by inhibition of the Ras-ERK pathway. Finally, we show that FAIM interacts with both Trk and p75 neurotrophin receptor NGF receptors in a ligand-dependent manner. These results reveal a new function of FAIM in promoting neurite outgrowth by a mechanism involving activation of the Ras-ERK pathway and NF-kappa B.