1
|
Guo L, Mann JR, Mauna JC, Copley KE, Wang H, Rubien JD, Odeh HM, Lin J, Lee BL, Ganser L, Robinson E, Kim KM, Murthy AC, Paul T, Portz B, Gleixner AM, Diaz Z, Carey JL, Smirnov A, Padilla G, Lavorando E, Espy C, Shang Y, Huang EJ, Chesi A, Fawzi NL, Myong S, Donnelly CJ, Shorter J. Defining RNA oligonucleotides that reverse deleterious phase transitions of RNA-binding proteins with prion-like domains. bioRxiv 2023:2023.09.04.555754. [PMID: 37732211 PMCID: PMC10508739 DOI: 10.1101/2023.09.04.555754] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
RNA-binding proteins with prion-like domains, such as FUS and TDP-43, condense into functional liquids, which can transform into pathological fibrils that underpin fatal neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). Here, we define short RNAs (24-48 nucleotides) that prevent FUS fibrillization by promoting liquid phases, and distinct short RNAs that prevent and, remarkably, reverse FUS condensation and fibrillization. These activities require interactions with multiple RNA-binding domains of FUS and are encoded by RNA sequence, length, and structure. Importantly, we define a short RNA that dissolves aberrant cytoplasmic FUS condensates, restores nuclear FUS, and mitigates FUS proteotoxicity in optogenetic models and human motor neurons. Another short RNA dissolves aberrant cytoplasmic TDP-43 condensates, restores nuclear TDP-43, and mitigates TDP-43 proteotoxicity. Since short RNAs can be effectively delivered to the human brain, these oligonucleotides could have therapeutic utility for ALS/FTD and related disorders.
Collapse
|
2
|
Gleixner AM, Verdone BM, Otte CG, Anderson EN, Ramesh N, Shapiro OR, Gale JR, Mauna JC, Mann JR, Copley KE, Daley EL, Ortega JA, Cicardi ME, Kiskinis E, Kofler J, Pandey UB, Trotti D, Donnelly CJ. NUP62 localizes to ALS/FTLD pathological assemblies and contributes to TDP-43 insolubility. Nat Commun 2022; 13:3380. [PMID: 35697676 PMCID: PMC9192689 DOI: 10.1038/s41467-022-31098-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 06/03/2022] [Indexed: 01/12/2023] Open
Abstract
A G4C2 hexanucleotide repeat expansion in the C9orf72 gene is the most common genetic cause of ALS and FTLD (C9-ALS/FTLD) with cytoplasmic TDP-43 inclusions observed in regions of neurodegeneration. The accumulation of repetitive RNAs and dipeptide repeat protein (DPR) are two proposed mechanisms of toxicity in C9-ALS/FTLD and linked to impaired nucleocytoplasmic transport. Nucleocytoplasmic transport is regulated by the phenylalanine-glycine nucleoporins (FG nups) that comprise the nuclear pore complex (NPC) permeability barrier. However, the relationship between FG nups and TDP-43 pathology remains elusive. Our studies show that nuclear depletion and cytoplasmic mislocalization of one FG nup, NUP62, is linked to TDP-43 mislocalization in C9-ALS/FTLD iPSC neurons. Poly-glycine arginine (GR) DPR accumulation initiates the formation of cytoplasmic RNA granules that recruit NUP62 and TDP-43. Cytoplasmic NUP62 and TDP-43 interactions promotes their insolubility and NUP62:TDP-43 inclusions are frequently found in C9orf72 ALS/FTLD as well as sporadic ALS/FTLD postmortem CNS tissue. Our findings indicate NUP62 cytoplasmic mislocalization contributes to TDP-43 proteinopathy in ALS/FTLD.
Collapse
Affiliation(s)
- Amanda M Gleixner
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
| | - Brandie Morris Verdone
- Department of Neuroscience, Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Charlton G Otte
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
- Physician Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Eric N Anderson
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Nandini Ramesh
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
| | - Olivia R Shapiro
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
| | - Jenna R Gale
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
| | - Jocelyn C Mauna
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
| | - Jacob R Mann
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Katie E Copley
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
| | - Elizabeth L Daley
- The Ken & Ruth Davee Department of Neurology, Northwestern University of Feinberg School of Medicine, Chicago, IL, USA
| | - Juan A Ortega
- The Ken & Ruth Davee Department of Neurology, Northwestern University of Feinberg School of Medicine, Chicago, IL, USA
| | - Maria Elena Cicardi
- Department of Neuroscience, Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Evangelos Kiskinis
- The Ken & Ruth Davee Department of Neurology, Northwestern University of Feinberg School of Medicine, Chicago, IL, USA
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Julia Kofler
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Udai B Pandey
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Davide Trotti
- Department of Neuroscience, Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Christopher J Donnelly
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA.
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
| |
Collapse
|
3
|
Mann JR, Gleixner AM, Mauna JC, Gomes E, DeChellis-Marks MR, Needham PG, Copley KE, Hurtle B, Portz B, Pyles NJ, Guo L, Calder CB, Wills ZP, Pandey UB, Kofler JK, Brodsky JL, Thathiah A, Shorter J, Donnelly CJ. RNA Binding Antagonizes Neurotoxic Phase Transitions of TDP-43. Neuron 2019; 102:321-338.e8. [PMID: 30826182 DOI: 10.1016/j.neuron.2019.01.048] [Citation(s) in RCA: 287] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 11/25/2018] [Accepted: 01/18/2019] [Indexed: 12/13/2022]
Abstract
TDP-43 proteinopathy is a pathological hallmark of amyotrophic lateral sclerosis and frontotemporal dementia where cytoplasmic TDP-43 inclusions are observed within degenerating regions of patient postmortem tissue. The mechanism by which TDP-43 aggregates has remained elusive due to technological limitations, which prevent the analysis of specific TDP-43 interactions in live cells. We present an optogenetic approach to reliably induce TDP-43 proteinopathy under spatiotemporal control. We show that the formation of pathologically relevant inclusions is driven by aberrant interactions between low-complexity domains of TDP-43 that are antagonized by RNA binding. Although stress granules are hypothesized to be a conduit for seeding TDP-43 proteinopathy, we demonstrate pathological inclusions outside these RNA-rich structures. Furthermore, we show that aberrant phase transitions of cytoplasmic TDP-43 are neurotoxic and that treatment with oligonucleotides composed of TDP-43 target sequences prevent inclusions and rescue neurotoxicity. Collectively, these studies provide insight into the mechanisms that underlie TDP-43 proteinopathy and present a potential avenue for therapeutic intervention.
Collapse
Affiliation(s)
- Jacob R Mann
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Amanda M Gleixner
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA
| | - Jocelyn C Mauna
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA
| | - Edward Gomes
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael R DeChellis-Marks
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Patrick G Needham
- Department of Biological Sciences, Kenneth P. Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Katie E Copley
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA
| | - Bryan Hurtle
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA
| | - Bede Portz
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Noah J Pyles
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA
| | - Lin Guo
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christopher B Calder
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA
| | - Zachary P Wills
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Udai B Pandey
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Julia K Kofler
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA; Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jeffrey L Brodsky
- Department of Biological Sciences, Kenneth P. Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA; Center for Protein Conformational Diseases, Kenneth P. Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Amantha Thathiah
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christopher J Donnelly
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA; Center for Protein Conformational Diseases, Kenneth P. Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA.
| |
Collapse
|
4
|
Kirschmann EKZ, Mauna JC, Willis CM, Foster RL, Chipman AM, Thiels E. Appetitive cue-evoked ERK signaling in the nucleus accumbens requires NMDA and D1 dopamine receptor activation and regulates CREB phosphorylation. ACTA ACUST UNITED AC 2014; 21:606-15. [PMID: 25322796 PMCID: PMC4201811 DOI: 10.1101/lm.035113.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Conditioned stimuli (CS) can modulate reward-seeking behavior. This modulatory effect can be maladaptive and has been implicated in excessive reward seeking and relapse to drug addiction. We previously demonstrated that exposure to an appetitive CS causes an increase in the activation of extracellular signal-regulated kinase (ERK) and cyclic-AMP response-element binding protein (CREB) in the nucleus accumbens (NAc) of rats, and that CS-evoked ERK activation is critical for CS control over reward seeking. To elucidate the mechanism that mediates CS-driven ERK activation in the NAc, we selectively blocked NMDA glutamate or D1 dopamine receptors in the NAc. To determine whether CS-driven ERK and CREB activation are linked, we selectively blocked ERK signaling in the NAc. We found that both NMDA and D1 receptors are critical for CS-driven ERK signaling in the NAc, and that this recruitment of the ERK cascade is responsible for increased CREB activation in the presence of the CS. Our findings suggest that activation of the NMDAR-D1R/ERK/CREB signal transduction pathway plays a critical role in the control of reward-seeking behavior by reward-predictive cues.
Collapse
Affiliation(s)
- Erin K Z Kirschmann
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Jocelyn C Mauna
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Cory M Willis
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Rebecca L Foster
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Amanda M Chipman
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Edda Thiels
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| |
Collapse
|
5
|
Anderson WD, Galván EJ, Mauna JC, Thiels E, Barrionuevo G. Properties and functional implications of I (h) in hippocampal area CA3 interneurons. Pflugers Arch 2011; 462:895-912. [PMID: 21938402 DOI: 10.1007/s00424-011-1025-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 08/24/2011] [Accepted: 08/29/2011] [Indexed: 12/26/2022]
Abstract
The present study examines the biophysical properties and functional implications of I (h) in hippocampal area CA3 interneurons with somata in strata radiatum and lacunosum-moleculare. Characterization studies showed a small maximum h-conductance (2.6 ± 0.3 nS, n = 11), shallow voltage dependence with a hyperpolarized half-maximal activation (V (1/2) = -91 mV), and kinetics characterized by double-exponential functions. The functional consequences of I (h) were examined with regard to temporal summation and impedance measurements. For temporal summation experiments, 5-pulse mossy fiber input trains were activated. Blocking I (h) with 50 μM ZD7288 resulted in an increase in temporal summation, suggesting that I (h) supports sensitivity of response amplitude to relative input timing. Impedance was assessed by applying sinusoidal current commands. From impedance measurements, we found that I (h) did not confer theta-band resonance, but flattened the impedance-frequency relations instead. Double immunolabeling for hyperpolarization-activated cyclic nucleotide-gated proteins and glutamate decarboxylase 67 suggests that all four subunits are present in GABAergic interneurons from the strata considered for electrophysiological studies. Finally, a model of I (h) was employed in computational analyses to confirm and elaborate upon the contributions of I (h) to impedance and temporal summation.
Collapse
Affiliation(s)
- Warren D Anderson
- Department of Neuroscience, University of Pittsburgh, A210 Langley Hall, Pittsburgh, PA 15260, USA
| | | | | | | | | |
Collapse
|
6
|
Mauna JC, Miyamae T, Pulli B, Thiels E. Protein phosphatases 1 and 2A are both required for long-term depression and associated dephosphorylation of cAMP response element binding protein in hippocampal area CA1 in vivo. Hippocampus 2010; 21:1093-104. [PMID: 20824729 DOI: 10.1002/hipo.20823] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2010] [Indexed: 01/24/2023]
Abstract
Evidence shows that the serine/threonine protein phosphatase 1 (PP1) plays a critical role in synaptic plasticity and memory. Little is known about the contribution of the serine/threonine phosphatase 1 (PP2A) to synaptic plasticity. Both protein phosphatases can target the transcription factor cAMP response element binding protein (CREB), whose phosphorylation at Ser133, we previously found, was downregulated during long-term depression (LTD) of glutamatergic transmission in area CA1 of the adult hippocampus in vivo. Other work from our group showed that the activity of PP2A, as well as that of PP1, is increased after LTD induction in area CA1 in vivo. We therefore investigated here whether both protein phosphatases are necessary for LTD in area CA1, and whether they both are involved in the LTD-associated modification of CREB. We found that inhibition of either PP1 or PP2A interferes with the establishment of LTD. Furthermore, inhibition of either enzyme alone abrogated the LTD-associated dephosphorylation of CREB. Interestingly, inhibition of PP1 disrupted CREB dephosphosphorylation rapidly after LTD-inducing stimulation, whereas inhibition of PP2A did not blunt the CREB modification until a later time point. Thus, both PP1 and PP2A regulate CREB during LTD in area CA1, although possibly through different signaling pathways. Our results demonstrate that PP2A, similar to PP1, plays an essential role in the molecular events that underlie LTD at glutamatergic synapses in hippocampal area CA1 in vivo. We propose that one of the mechanisms through which these protein phosphatases may contribute to the prolonged maintenance of LTD is through the regulation of CREB.
Collapse
Affiliation(s)
- Jocelyn C Mauna
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
| | | | | | | |
Collapse
|
7
|
Lazo OM, Mauna JC, Pissani CA, Inestrosa NC, Bronfman FC. Axotomy-induced neurotrophic withdrawal causes the loss of phenotypic differentiation and downregulation of NGF signalling, but not death of septal cholinergic neurons. Mol Neurodegener 2010; 5:5. [PMID: 20205865 PMCID: PMC2826326 DOI: 10.1186/1750-1326-5-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 01/19/2010] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Septal cholinergic neurons account for most of the cholinergic innervations of the hippocampus, playing a key role in the regulation of hippocampal synaptic activity. Disruption of the septo-hippocampal pathway by an experimental transection of the fimbria-fornix drastically reduces the target-derived trophic support received by cholinergic septal neurons, mainly nerve growth factor (NGF) from the hippocampus. Axotomy of cholinergic neurons induces a reduction in the number of neurons positive for cholinergic markers in the medial septum. In several studies, the reduction of cholinergic markers has been interpreted as analogous to the neurodegeneration of cholinergic cells, ruling out the possibility that neurons lose their cholinergic phenotype without dying. Understanding the mechanism of cholinergic neurodegeneration after axotomy is relevant, since this paradigm has been extensively explored as an animal model of the cholinergic impairment observed in neuropathologies such as Alzheimer's disease.The principal aim of this study was to evaluate, using modern quantitative confocal microscopy, neurodegenerative changes in septal cholinergic neurons after axotomy and to assess their response to delayed infusion of NGF in rats. RESULTS We found that there is a slow reduction of cholinergic cells labeled by ChAT and p75 after axotomy. However, this phenomenon is not accompanied by neurodegenerative changes or by a decrease in total neuronal number in the medial septum. Although the remaining axotomized-neurons appear healthy, they are unable to respond to delayed NGF infusion. CONCLUSIONS Our results demonstrate that at 3 weeks, axotomized cholinergic neurons lose their cholinergic phenotype without dying and down-regulate their NGF-receptors, precluding the possibility of a response to NGF. Therefore, the physiological role of NGF in the adult septal cholinergic system is to support phenotypic differentiation and not survival of neurons. This evidence raises questions about the relationship between transcriptional regulation of the cholinergic phenotype by retrograde-derived trophic signaling and the transcriptional changes experienced when retrograde transport is impaired due to neuropathological conditions.
Collapse
Affiliation(s)
- Oscar M Lazo
- Department of Physiology, Neurobiology Unit, Center of Ageing and Regeneration (CARE), Nucleus Millennium in Regenerative Biology (MINREB), Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile, Alameda 340, CP 8331010, Santiago, Chile
| | - Jocelyn C Mauna
- Department of Physiology, Neurobiology Unit, Center of Ageing and Regeneration (CARE), Nucleus Millennium in Regenerative Biology (MINREB), Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile, Alameda 340, CP 8331010, Santiago, Chile
- Current address: Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Claudia A Pissani
- Department of Physiology, Neurobiology Unit, Center of Ageing and Regeneration (CARE), Nucleus Millennium in Regenerative Biology (MINREB), Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile, Alameda 340, CP 8331010, Santiago, Chile
| | - Nibaldo C Inestrosa
- Department of Cellular Biology, Center of Ageing and Regeneration (CARE), Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile, Alameda 340, CP 8331010, Santiago, Chile
| | - Francisca C Bronfman
- Department of Physiology, Neurobiology Unit, Center of Ageing and Regeneration (CARE), Nucleus Millennium in Regenerative Biology (MINREB), Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile, Alameda 340, CP 8331010, Santiago, Chile
| |
Collapse
|
8
|
Shiflett MW, Mauna JC, Chipman AM, Peet E, Thiels E. Appetitive Pavlovian conditioned stimuli increase CREB phosphorylation in the nucleus accumbens. Neurobiol Learn Mem 2009; 92:451-4. [PMID: 19248836 DOI: 10.1016/j.nlm.2009.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 02/17/2009] [Accepted: 02/17/2009] [Indexed: 12/27/2022]
Abstract
The transcription factor cAMP response element-binding protein (CREB) in the nucleus accumbens (NAc) has been shown to regulate an animal's behavioral responsiveness to emotionally salient stimuli, and an increase in CREB phosphorylation in the NAc has been observed during exposure to rewarding stimuli, such as drugs of abuse. Here we show that CREB phosphorylation increases in the NAc also during exposure to cues that an animal has associated with delivery of natural rewards. Adult male Sprague-Dawley rats (rattus norvegicus) were trained to associate an auditory stimulus with delivery of food pellets, and CREB phosphorylation was examined in the striatum following training. We found that repeated tone-food pairings resulted in an increase in CREB phosphorylation in the NAc but not in the adjacent dorsal striatum or in the NAc 3h after the final training session. We further found that the cue itself, as opposed to the food pellets, the training context, or tone-food pairings, was sufficient to increase CREB phosphorylation in the NAc. These results suggest that the processing of primary rewarding stimuli and of environmental cues that predict them triggers similar accumbal signaling mechanisms.
Collapse
Affiliation(s)
- Michael W Shiflett
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | | | | | | | | |
Collapse
|