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Yang L, Ahammed MS, Wu P, Sternburg JO, Liu J, Wang X. Genetic blockade of the activation of 26S proteasomes by PKA is well tolerated by mice at baseline. AMERICAN JOURNAL OF CARDIOVASCULAR DISEASE 2024; 14:90-105. [PMID: 38764549 PMCID: PMC11101957 DOI: 10.62347/nswr6869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 02/17/2024] [Indexed: 05/21/2024]
Abstract
OBJECTIVE Proteasome activation by the cAMP-dependent protein kinase (PKA) was long suggested and recent studies using both cell cultures and genetically engineered mice have established that direct phosphorylation of RPN6/PSMD11 at Serine14 (pS14-RPN6) mediates the activation of 26S proteasomes by PKA. Genetic mimicry of pS14-RPN6 has been shown to be benign at baseline and capable of protecting against cardiac proteinopathy in mice. Here we report the results from a comprehensive baseline characterization of the Rpn6S14A mice (S14A), the first animal model of genetic blockade of the activation of 26S proteasomes by PKA. METHOD Wild type and homozygous S14A littermate mice were subjected to serial M-mode echocardiography at 1 through 7 months of age, to left ventricular (LV) catheterization via the carotid artery for assessment of LV mechanical performance, and to cardiac gravimetric analyses at 26 weeks of age. Mouse mortality and morbidity were monitored daily for up to one year. Males and females were studied in parallel. RESULTS Mice homozygous for S14A were viable and fertile and did not show discernible developmental abnormalities or increased mortality or morbidity compared with their Rpn6 wild type littermates by at least one year of age, the longest cohort observed thus far. Neither serial echocardiography nor hemodynamic assessments detected a remarkable difference in cardiac morphometry and function between S14A and wild type littermate mice. No cardiac gravimetric difference was observed. CONCLUSION The findings of the present study indicate that genetic blockade of the activation of 26S proteasomes by PKA is well tolerated by mice at baseline. Therefore, the S14A mouse provides a desirable genetic tool for further investigating the in vivo pathophysiological and pharmacological significance of pS14-RPN6.
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Affiliation(s)
- Liuqing Yang
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South DakotaVermillion, SD 57069, USA
| | - Md Salim Ahammed
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South DakotaVermillion, SD 57069, USA
| | - Penglong Wu
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South DakotaVermillion, SD 57069, USA
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, State Key Lab of Respiratory Disease, School of Basic Medical Sciences, Affiliated Cancer Hospital of Guangzhou Medical UniversityGuangzhou 511436, Guangdong, P. R. China
| | - Jack O Sternburg
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South DakotaVermillion, SD 57069, USA
| | - Jinbao Liu
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, State Key Lab of Respiratory Disease, School of Basic Medical Sciences, Affiliated Cancer Hospital of Guangzhou Medical UniversityGuangzhou 511436, Guangdong, P. R. China
| | - Xuejun Wang
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South DakotaVermillion, SD 57069, USA
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Farrell K, Auerbach A, Musaus M, Navabpour S, Liu C, Lin Y, Xie H, Jarome TJ. Phosphorylation of RPT6 Controls Its Ability to Bind DNA and Regulate Gene Expression in the Hippocampus of Male Rats during Memory Formation. J Neurosci 2024; 44:e1453232023. [PMID: 38124005 PMCID: PMC10860611 DOI: 10.1523/jneurosci.1453-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/31/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023] Open
Abstract
Memory formation requires coordinated control of gene expression, protein synthesis, and ubiquitin-proteasome system (UPS)-mediated protein degradation. The catalytic component of the UPS, the 26S proteasome, contains a 20S catalytic core surrounded by two 19S regulatory caps, and phosphorylation of the 19S cap regulatory subunit RPT6 at serine 120 (pRPT6-S120) has been widely implicated in controlling activity-dependent increases in proteasome activity. Recently, RPT6 was also shown to act outside the proteasome where it has a transcription factor-like role in the hippocampus during memory formation. However, little is known about the proteasome-independent function of "free" RPT6 in the brain or during memory formation and whether phosphorylation of S120 is required for this transcriptional control function. Here, we used RNA-sequencing along with novel genetic approaches and biochemical, molecular, and behavioral assays to test the hypothesis that pRPT6-S120 functions independently of the proteasome to bind DNA and regulate gene expression during memory formation. RNA-sequencing following siRNA-mediated knockdown of free RPT6 revealed 46 gene targets in the dorsal hippocampus of male rats following fear conditioning, where RPT6 was involved in transcriptional activation and repression. Through CRISPR-dCas9-mediated artificial placement of RPT6 at a target gene, we found that RPT6 DNA binding alone may be important for altering gene expression following learning. Further, CRISPR-dCas13-mediated conversion of S120 to glycine on RPT6 revealed that phosphorylation at S120 is necessary for RPT6 to bind DNA and properly regulate transcription during memory formation. Together, we reveal a novel function for phosphorylation of RPT6 in controlling gene transcription during memory formation.
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Affiliation(s)
- Kayla Farrell
- Departments of School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
| | - Aubrey Auerbach
- Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
| | - Shaghayegh Navabpour
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
| | - Catherine Liu
- Departments of School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
| | - Yu Lin
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg 24060, Virginia
| | - Hehuang Xie
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg 24060, Virginia
- Fralin Life Science Institute at Virginia Tech, Blacksburg 24060, Virginia
| | - Timothy J Jarome
- Departments of School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg 24060, Virginia
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Farrell K, Musaus M, Auerbach A, Navabpour S, Ray WK, Helm RF, Jarome TJ. Proteasome-independent K63 polyubiquitination selectively regulates ATP levels and proteasome activity during fear memory formation in the female amygdala. Mol Psychiatry 2023; 28:2594-2605. [PMID: 37198264 PMCID: PMC10615704 DOI: 10.1038/s41380-023-02112-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/26/2023] [Accepted: 05/05/2023] [Indexed: 05/19/2023]
Abstract
Females are more likely than males to develop post-traumatic stress disorder (PTSD). However, the neurobiological mechanisms responsible for these sex differences remain elusive. The ubiquitin proteasome system (UPS) is involved in fear memory formation and implicated in PTSD development. Despite this, proteasome-independent functions of the UPS have rarely been studied in the brain. Here, using a combination of molecular, biochemical, proteomic, behavioral, and novel genetic approaches, we investigated the role of proteasome-independent lysine-63 (K63)-polyubiquitination, the second most abundant ubiquitin modification in cells, in the amygdala during fear memory formation in male and female rats. Only females had increased levels of K63-polyubiquitination targeting in the amygdala following fear conditioning, which targeted proteins involved in ATP synthesis and proteasome function. CRISPR-dCas13b-mediated knockdown of K63-polyubiquitination in the amygdala via editing of the K63 codon in the major ubiquitin gene, Ubc, impaired fear memory in females, but not males, and caused a reduction in learning-related increases in ATP levels and proteasome activity in the female amygdala. These results suggest that proteasome-independent K63-polyubiquitination is selectively involved in fear memory formation in the female amygdala, where it is involved in the regulation of ATP synthesis and proteasome activity following learning. This indicates the first link between proteasome-independent and proteasome-dependent UPS functions in the brain during fear memory formation. Importantly, these data are congruent with reported sex differences in PTSD development and may contribute to our understanding of why females are more likely to develop PTSD than males.
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Affiliation(s)
- Kayla Farrell
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Aubrey Auerbach
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Shaghayegh Navabpour
- Translational Biology, Medicine and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | - W Keith Ray
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Richard F Helm
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Timothy J Jarome
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
- Translational Biology, Medicine and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, VA, USA.
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Yang L, Parajuli N, Wu P, Liu J, Wang X. Ser14-RPN6 Phosphorylation Mediates the Activation of 26S Proteasomes by cAMP and Protects against Cardiac Proteotoxic Stress in Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.05.535705. [PMID: 37066344 PMCID: PMC10104033 DOI: 10.1101/2023.04.05.535705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Background A better understanding of the regulation of proteasome activities can facilitate the search for new therapeutic strategies. A cell culture study shows that cAMP-dependent protein kinase (PKA) activates the 26S proteasome by phosphorylating Ser14 of RPN6 (pS14-RPN6), but this discovery and its physiological significance remain to be established in vivo . Methods Male and female mice with Ser14 of Rpn6 mutated to Ala (S14A) or Asp (S14D) to respectively block or mimic pS14-Rpn6 were created and used along with cells derived from them. cAMP/PKA were manipulated pharmacologically. Ubiquitin-proteasome system (UPS) functioning was evaluated with the GFPdgn reporter mouse and proteasomal activity assays. Impact of S14A and S14D on proteotoxicity was tested in mice and cardiomyocytes overexpressing the misfolded protein R120G-CryAB (R120G). Results PKA activation increased pS14-Rpn6 and 26S proteasome activities in wild-type (WT) but not S14A embryonic fibroblasts (MEFs), adult cardiomyocytes (AMCMs), and mouse hearts. Basal 26S proteasome activities were significantly greater in S14D myocardium and AMCMs than in WT counterparts. S14D::GFPdgn mice displayed significantly lower myocardial GFPdgn protein but not mRNA levels than GFPdgn mice. In R120G mice, a classic model of cardiac proteotoxicity, basal myocardial pS14-Rpn6 was significantly lower compared with non- transgenic littermates, which was not always associated with reduction of other phosphorylated PKA substrates. Cultured S14D neonatal cardiomyocytes displayed significantly faster proteasomal degradation of R120G than WT neonatal cardiomyocytes. Compared with R120G mice, S14D/S14D::R120G mice showed significantly greater myocardial proteasome activities, lower levels of total and K48-linked ubiquitin conjugates and of aberrant CryAB protein aggregates, less reactivation of fetal genes and cardiac hypertrophy, and delays in cardiac malfunction. Conclusions This study establishes in animals that pS14-Rpn6 mediates the activation of 26S proteasomes by PKA and that the reduced pS14-Rpn6 is a key pathogenic factor in cardiac proteinopathy, thereby identifies a new therapeutic target to reduce cardiac proteotoxicity.
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Ferrara NC, Kwapis JL, Trask S. Memory retrieval, reconsolidation, and extinction: Exploring the boundary conditions of post-conditioning cue exposure. Front Synaptic Neurosci 2023; 15:1146665. [PMID: 36937567 PMCID: PMC10017482 DOI: 10.3389/fnsyn.2023.1146665] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 02/17/2023] [Indexed: 03/06/2023] Open
Abstract
Following fear conditioning, behavior can be reduced by giving many CS-alone presentations in a process known as extinction or by presenting a few CS-alone presentations and interfering with subsequent memory reconsolidation. While the two share procedural similarities, both the behavioral outcomes and the neurobiological underpinnings are distinct. Here we review the neural and behavioral mechanisms that produce these separate behavioral reductions, as well as some factors that determine whether or not a retrieval-dependent reconsolidation process or an extinction process will be in effect.
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Affiliation(s)
- Nicole C. Ferrara
- Discipline of Physiology and Biophysics, Rosalind Franklin University, North Chicago, IL, United States
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University, North Chicago, IL, United States
| | - Janine L. Kwapis
- Department of Biology, The Pennsylvania State University, University Park, PA, United States
| | - Sydney Trask
- Department of Psychological Sciences, Purdue University, West Lafayette, IN, United States
- Purdue Institute for Integrative Neuroscience, West Lafayette, IN, United States
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Buneeva OA, Kopylov AT, Medvedev AE. Proteasome Interactome and Its Role in the Mechanisms of Brain Plasticity. BIOCHEMISTRY (MOSCOW) 2023; 88:319-336. [PMID: 37076280 DOI: 10.1134/s0006297923030033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
Abstract
Abstract
Proteasomes are highly conserved multienzyme complexes responsible for proteolytic degradation of the short-lived, regulatory, misfolded, and damaged proteins. They play an important role in the processes of brain plasticity, and decrease in their function is accompanied by the development of neurodegenerative pathology. Studies performed in different laboratories both on cultured mammalian and human cells and on preparations of the rat and rabbit brain cortex revealed a large number of proteasome-associated proteins. Since the identified proteins belong to certain metabolic pathways, multiple enrichment of the proteasome fraction with these proteins indicates their important role in proteasome functioning. Extrapolation of the experimental data, obtained on various biological objects, to the human brain suggests that the proteasome-associated proteins account for at least 28% of the human brain proteome. The proteasome interactome of the brain contains a large number of proteins involved in the assembly of these supramolecular complexes, regulation of their functioning, and intracellular localization, which could be changed under different conditions (for example, during oxidative stress) or in different phases of the cell cycle. In the context of molecular functions of the Gene Ontology (GO) Pathways, the proteins of the proteasome interactome mediate cross-talk between components of more than 30 metabolic pathways annotated in terms of GO. The main result of these interactions is binding of adenine and guanine nucleotides, crucial for realization of the nucleotide-dependent functions of the 26S and 20S proteasomes. Since the development of neurodegenerative pathology is often associated with regioselective decrease in the functional activity of proteasomes, a positive therapeutic effect would be obviously provided by the factors increasing proteasomal activity. In any case, pharmacological regulation of the brain proteasomes seems to be realized through the changes in composition and/or activity of the proteins associated with proteasomes (deubiquitinase, PKA, CaMKIIα, etc.).
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Affiliation(s)
- Olga A Buneeva
- Institute of Biomedical Chemistry, Moscow, 119121, Russia
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7
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Sbardella D, Tundo GR, Mecchia A, Palumbo C, Atzori MG, Levati L, Boccaccini A, Caccuri AM, Cascio P, Lacal PM, Graziani G, Varano M, Coletta M, Parravano M. A novel and atypical NF-KB pro-inflammatory program regulated by a CamKII-proteasome axis is involved in the early activation of Muller glia by high glucose. Cell Biosci 2022; 12:108. [PMID: 35842713 PMCID: PMC9287993 DOI: 10.1186/s13578-022-00839-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 06/28/2022] [Indexed: 11/29/2022] Open
Abstract
Background Diabetic retinopathy (DR) is a microvascular complication of diabetes with a heavy impact on the quality of life of subjects and with a dramatic burden for health and economic systems on a global scale. Although the pathogenesis of DR is largely unknown, several preclinical data have pointed out to a main role of Muller glia (MG), a cell type which spans across the retina layers providing nourishment and support for Retina Ganglion Cells (RGCs), in sensing hyper-glycemia and in acquiring a pro-inflammatory polarization in response to this insult. Results By using a validated experimental model of DR in vitro, rMC1 cells challenged with high glucose, we uncovered the induction of an early (within minutes) and atypical Nuclear Factor-kB (NF-kB) signalling pathway regulated by a calcium-dependent calmodulin kinase II (CamKII)-proteasome axis. Phosphorylation of proteasome subunit Rpt6 (at Serine 120) by CamKII stimulated the accelerated turnover of IkBα (i.e., the natural inhibitor of p65-50 transcription factor), regardless of the phosphorylation at Serine 32 which labels canonical NF-kB signalling. This event allowed the p65-p50 heterodimer to migrate into the nucleus and to induce transcription of IL-8, Il-1β and MCP-1. Pharmacological inhibition of CamKII as well as proteasome inhibition stopped this pro-inflammatory program, whereas introduction of a Rpt6 phospho-dead mutant (Rpt6-S120A) stimulated a paradoxical effect on NF-kB probably through the activation of a compensatory mechanism which may involve phosphorylation of 20S α4 subunit. Conclusions This study introduces a novel pathway of MG activation by high glucose and casts some light on the biological relevance of proteasome post-translational modifications in modulating pathways regulated through targeted proteolysis. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-022-00839-x. High glucose quickly induces an atypical NF-kB pro-inflammatory program. CamKII phosphorylation of Rpt6 subunit of the proteasome stimulates IkBα turnover and p65-p50 release. Inhibition of either CamkII or proteasome blocks this pathway.
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Yang G, Dong Q, Yang H, Wang F, Chen L, Tang J, Huang G, Zhao Y. Changes Observed in Potential Key Candidate Genes of Peripheral Immunity Induced by Tai Chi among Patients with Parkinson's Disease. Genes (Basel) 2022; 13:genes13101863. [PMID: 36292747 PMCID: PMC9601924 DOI: 10.3390/genes13101863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/13/2022] [Accepted: 10/14/2022] [Indexed: 11/04/2022] Open
Abstract
Parkinson’s disease (PD) is a common progressive neurodegenerative disease characterized by motor dysfunction. Although the inhibition of inflammation by Tai Chi has been demonstrated to involve a peripheral cytokine response and may play an important role in improving the motor function of PD patients, the related specific molecular mechanisms of the peripheral immune response to Tai Chi are not fully understood. The microarray dataset ‘GSE124676’ for the peripheral immune response to Tai Chi of PD patients was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened and analyzed using weighted gene co-expression network analysis (WGCNA). A total of 136 DEGs were found in the PD patients after Tai Chi, suggesting an effect of Tai Chi on the peripheral immunity of PD patients. The DEGs are mainly involved in neutrophil activation, T-cell activation, and NOD-like receptor and IL-17 signaling pathways. Furthermore, six key candidate genes (FOS, FOSB, JUNB, ZFP36, CAMP and LCN2) that are involved in peripheral inflammation and the inhibition of inflammation induced by Tai Chi were observed. The results in the present study could be conducive to comprehensively understanding the molecular mechanism involved in the effect of Tai Chi on peripheral inflammation in PD patients and providing novel targets for future advanced research.
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Affiliation(s)
- Guang Yang
- Physical Education Department, Shanghai Jiao Tong University, Shanghai 200042, China
| | - Qun Dong
- Department of Bioinformatics and Biostatistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Huixin Yang
- Institute of Nation Traditional Sports, Harbin Sport University, Harbin 150006, China
| | - Fan Wang
- Institute of Nation Traditional Sports, Harbin Sport University, Harbin 150006, China
| | - Linwei Chen
- Institute of Nation Traditional Sports, Harbin Sport University, Harbin 150006, China
| | - Junze Tang
- Institute of Nation Traditional Sports, Harbin Sport University, Harbin 150006, China
| | - Guoyuan Huang
- Pott College of Science, Engineering and Education, University of Southern Indiana, Indiana, IN 47712, USA
- Correspondence: (G.H.); (Y.Z.)
| | - Ying Zhao
- Physical Education Department, Shanghai Jiao Tong University, Shanghai 200042, China
- Correspondence: (G.H.); (Y.Z.)
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Farrell K, Auerbach A, Musaus M, Jarome TJ. The epigenetic role of proteasome subunit RPT6 during memory formation in female rats. Learn Mem 2022; 29:256-264. [PMID: 36206393 PMCID: PMC9488026 DOI: 10.1101/lm.053498.121] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/10/2022] [Indexed: 11/24/2022]
Abstract
Reports of sex differences in the neurobiology of memory formation are becoming more prevalent. Despite this, much remains unknown about the role of sex in this process. We previously reported the first evidence of a novel epigenetic role for proteasome subunit RPT6 during memory formation in the hippocampus of male rodents whereby it associated with monoubiquitinated histone H2B (H2Bubi). Here, we used molecular, biochemical, and behavioral approaches to investigate whether RPT6 has a similar epigenetic role during memory formation in female rats. Following contextual fear conditioning, we found that RPT6 levels and DNA binding at regions coding for c-fos, the previously identified target of RPT6 in males, were unchanged in the hippocampus of females and that loss of RPT6 did not alter learning-induced increases in c-fos However, RPT6 was in complex with H2Bubi in the female hippocampus and this association increased with fear conditioning, suggesting that it could still retain an epigenetic function. Consistent with this, hippocampal siRNA-mediated knockdown of the RPT6-coding gene, Psmc5, impaired memory in females. These results suggest that while RPT6 does associate with epigenetic H2Bubi during memory formation in both males and females, it has sex-specific gene targets during the memory consolidation process.
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Affiliation(s)
- Kayla Farrell
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Aubrey Auerbach
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Timothy J Jarome
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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10
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Beamish SB, Gross KS, Anderson MM, Helmstetter FJ, Frick KM. Sex differences in training-induced activity of the ubiquitin proteasome system in the dorsal hippocampus and medial prefrontal cortex of male and female mice. Learn Mem 2022; 29:302-311. [PMID: 36206392 PMCID: PMC9488027 DOI: 10.1101/lm.053492.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 07/08/2022] [Indexed: 11/25/2022]
Abstract
The ubiquitin proteasome system (UPS) is a primary mechanism through which proteins are degraded in cells. UPS activity in the dorsal hippocampus (DH) is necessary for multiple types of memory, including object memory, in male rodents. However, sex differences in DH UPS activation after fear conditioning suggest that other forms of learning may also differentially regulate DH UPS activity in males and females. Here, we examined markers of UPS activity in the synaptic and cytoplasmic fractions of DH and medial prefrontal cortex (mPFC) tissue collected 1 h following object training. In males, training increased phosphorylation of proteasomal subunit Rpt6, 20S proteasome activity, and the amount of PSD-95 in the DH synaptic fraction, as well as proteasome activity in the mPFC synaptic fraction. In females, training did not affect measures of UPS or synaptic activity in the DH synaptic fraction or in either mPFC fraction but increased Rpt6 phosphorylation in the DH cytoplasmic fraction. Overall, training-induced UPS activity was greater in males than in females, greater in the DH than in the mPFC, and greater in synaptic fractions than in cytosol. These data suggest that object training drives sex-specific alterations in UPS activity across brain regions and subcellular compartments important for memory.
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Affiliation(s)
- Sarah B Beamish
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
| | - Kellie S Gross
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
| | - McKenna M Anderson
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
| | - Karyn M Frick
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
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11
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Beamish SB, Frick KM. A Putative Role for Ubiquitin-Proteasome Signaling in Estrogenic Memory Regulation. Front Behav Neurosci 2022; 15:807215. [PMID: 35145382 PMCID: PMC8821141 DOI: 10.3389/fnbeh.2021.807215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/20/2021] [Indexed: 12/31/2022] Open
Abstract
Sex steroid hormones such as 17β-estradiol (E2) are critical neuromodulators of hippocampal synaptic plasticity and hippocampus-dependent memory in both males and females. However, the mechanisms through which E2 regulates memory formation in both sexes remain unclear. Research to date suggests that E2 regulates hippocampus-dependent memory by activating numerous cell-signaling cascades to promote the synthesis of proteins that support structural changes at hippocampal synapses. However, this work has largely overlooked the equally important contributions of protein degradation mediated by the ubiquitin proteasome system (UPS) in remodeling the synapse. Despite being critically implicated in synaptic plasticity and successful formation of long-term memories, it remains unclear whether protein degradation mediated by the UPS is necessary for E2 to exert its beneficial effects on hippocampal plasticity and memory formation. The present article provides an overview of the receptor and signaling mechanisms so far identified as critical for regulating hippocampal E2 and UPS function in males and females, with a particular emphasis on the ways in which these mechanisms overlap to support structural integrity and protein composition of hippocampal synapses. We argue that the high degree of correspondence between E2 and UPS activity warrants additional study to examine the contributions of ubiquitin-mediated protein degradation in regulating the effects of sex steroid hormones on cognition.
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12
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Farrell K, Musaus M, Navabpour S, Martin K, Ray WK, Helm RF, Jarome TJ. Proteomic Analysis Reveals Sex-Specific Protein Degradation Targets in the Amygdala During Fear Memory Formation. Front Mol Neurosci 2021; 14:716284. [PMID: 34658783 PMCID: PMC8511838 DOI: 10.3389/fnmol.2021.716284] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/01/2021] [Indexed: 11/25/2022] Open
Abstract
Ubiquitin-proteasome mediated protein degradation has been widely implicated in fear memory formation in the amygdala. However, to date, the protein targets of the proteasome remain largely unknown, limiting our understanding of the functional significance for protein degradation in fear memory formation. Additionally, whether similar proteins are targeted by the proteasome between sexes has yet to be explored. Here, we combined a degradation-specific K48 Tandem Ubiquitin Binding Entity (TUBE) with liquid chromatography mass spectrometry (LC/MS) to identify the target substrates of the protein degradation process in the amygdala of male and female rats following contextual fear conditioning. We found that males (43) and females (77) differed in the total number of proteins that had significant changes in K48 polyubiquitin targeting in the amygdala following fear conditioning. Many of the identified proteins (106) had significantly reduced levels in the K48-purified samples 1 h after fear conditioning, suggesting active degradation of the substrate due to learning. Interestingly, only 3 proteins overlapped between sexes, suggesting that targets of the protein degradation process may be sex-specific. In females, many proteins with altered abundance in the K48-purified samples were involved in vesicle transport or are associated with microtubules. Conversely, in males, proteins involved in the cytoskeleton, ATP synthesis and cell signaling were found to have significantly altered abundance. Only 1 protein had an opposite directional change in abundance between sexes, LENG1, which was significantly enhanced in males while lower in females. This suggests a more rapid degradation of this protein in females during fear memory formation. Interestingly, GFAP, a critical component of astrocyte structure, was a target of K48 polyubiquitination in both males and females, indicating that protein degradation is likely occurring in astrocytes following fear conditioning. Western blot assays revealed reduced levels of these target substrates following fear conditioning in both sexes, confirming that the K48 polyubiquitin was targeting these proteins for degradation. Collectively, this study provides strong evidence that sex differences exist in the protein targets of the degradation process in the amygdala following fear conditioning and critical information regarding how ubiquitin-proteasome mediated protein degradation may contribute to fear memory formation in the brain.
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Affiliation(s)
- Kayla Farrell
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Shaghayegh Navabpour
- Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, United States
| | - Kiley Martin
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - W Keith Ray
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Richard F Helm
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Timothy J Jarome
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States.,School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States.,Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, United States
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13
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Martin K, Musaus M, Navabpour S, Gustin A, Ray WK, Helm RF, Jarome TJ. Females, but not males, require protein degradation in the hippocampus for contextual fear memory formation. ACTA ACUST UNITED AC 2021; 28:248-253. [PMID: 34266989 PMCID: PMC8284313 DOI: 10.1101/lm.053429.121] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/07/2021] [Indexed: 11/30/2022]
Abstract
Strong evidence supports a role for protein degradation in fear memory formation. However, these data have been largely done in only male animals. Here, we found that following contextual fear conditioning, females, but not males, had increased levels of proteasome activity and K48 polyubiquitin protein targeting in the dorsal hippocampus, the latter of which occurred at chaperones or RNA processing proteins. In vivo CRISPR–dCas9-mediated repression of protein degradation in the dorsal hippocampus impaired contextual fear memory in females, but not males. These results suggest a sex-specific role for protein degradation in the hippocampus during the consolidation of a contextual fear memory.
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Affiliation(s)
- Kiley Martin
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Shaghayegh Navabpour
- Fralin Biomedical Research Institute, Department of Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, Virginia 24016, USA
| | - Aspen Gustin
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - W Keith Ray
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Richard F Helm
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Timothy J Jarome
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.,Fralin Biomedical Research Institute, Department of Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, Virginia 24016, USA.,Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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14
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Musaus M, Farrell K, Navabpour S, Ray WK, Helm RF, Jarome TJ. Sex-Specific Linear Polyubiquitination Is a Critical Regulator of Contextual Fear Memory Formation. Front Behav Neurosci 2021; 15:709392. [PMID: 34305548 PMCID: PMC8298817 DOI: 10.3389/fnbeh.2021.709392] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 06/22/2021] [Indexed: 12/27/2022] Open
Abstract
Strong evidence supports that protein ubiquitination is a critical regulator of fear memory formation. However, as this work has focused on protein degradation, it is currently unknown whether polyubiquitin modifications that are independent of the proteasome are involved in learning-dependent synaptic plasticity. Here, we present the first evidence that atypical linear (M1) polyubiquitination, the only ubiquitin chain that does not occur at a lysine site and is largely independent of the proteasome, is critically involved in contextual fear memory formation in the amygdala in a sex-specific manner. Using immunoblot and unbiased proteomic analyses, we found that male (49) and female (14) rats both had increased levels of linear polyubiquitinated substrates following fear conditioning, though none of these protein targets overlapped between sexes. In males, target protein functions involved cell junction and axonal guidance signaling, while in females the primary target was Adiponectin A, a critical regulator of neuroinflammation, synaptic plasticity, and memory, suggesting sex-dependent functional roles for linear polyubiquitination during fear memory formation. Consistent with these increases, in vivo siRNA-mediated knockdown of Rnf31, an essential component of the linear polyubiquitin E3 complex LUBAC, in the amygdala impaired contextual fear memory in both sexes without affecting memory retrieval. Collectively, these results provide the first evidence that proteasome-independent linear polyubiquitination is a critical regulator of fear memory formation, expanding the potential roles of ubiquitin-signaling in learning-dependent synaptic plasticity. Importantly, our data identify a novel sex difference in the functional role of, but not a requirement for, linear polyubiquitination in fear memory formation.
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Affiliation(s)
- Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Kayla Farrell
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Shaghayegh Navabpour
- Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, United States
| | - W. Keith Ray
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Richard F. Helm
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Timothy J. Jarome
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
- Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, United States
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15
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T-Type Ca 2+ Enhancer SAK3 Activates CaMKII and Proteasome Activities in Lewy Body Dementia Mice Model. Int J Mol Sci 2021; 22:ijms22126185. [PMID: 34201181 PMCID: PMC8228122 DOI: 10.3390/ijms22126185] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/01/2021] [Accepted: 06/03/2021] [Indexed: 12/28/2022] Open
Abstract
Lewy bodies are pathological characteristics of Lewy body dementia (LBD) and are composed of α-synuclein (α-Syn), which is mostly degraded via the ubiquitin–proteasome system. More importantly, 26S proteasomal activity decreases in the brain of LBD patients. We recently introduced a T-type calcium channel enhancer SAK3 (ethyl-8-methyl-2,4-dioxo-2-(piperidin-1-yl)- 2H-spiro[cyclopentane-1,3-imidazo [1,2-a]pyridin]-2-ene-3-carboxylate) for Alzheimer’s disease therapeutics. SAK3 enhanced the proteasome activity via CaMKII activation in amyloid precursor protein knock-in mice, promoting the degradation of amyloid-β plaques to improve cognition. At this point, we addressed whether SAK3 promotes the degradation of misfolded α-Syn and the aggregates in α-Syn preformed fibril (PFF)-injected mice. The mice were injected with α-Syn PFF in the dorsal striatum, and SAK3 (0.5 or 1.0 mg/kg) was administered orally for three months, either immediately or during the last month after injection. SAK3 significantly inhibited the accumulation of fibrilized phosphorylated-α-Syn in the substantia nigra. Accordingly, SAK3 significantly recovered mesencephalic dopamine neurons from cell death. Decreased α-Syn accumulation was closely associated with increased proteasome activity. Elevated CaMKII/Rpt-6 signaling possibly mediates the enhanced proteasome activity after SAK3 administration in the cortex and hippocampus. CaMKII/Rpt-6 activation also accounted for improved memory and cognition in α-Syn PFF-injected mice. These findings indicate that CaMKII/Rpt-6-dependent proteasomal activation by SAK3 recovers from α-Syn pathology in LBD.
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16
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Lin B, Alganem K, O'Donovan SM, Jin Z, Naghavi F, Miller OA, Ortyl TC, Ruan YC, McCullumsmith RE, Du J. Activation of acid-sensing ion channels by carbon dioxide regulates amygdala synaptic protein degradation in memory reconsolidation. Mol Brain 2021; 14:78. [PMID: 33962650 PMCID: PMC8106190 DOI: 10.1186/s13041-021-00786-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 04/26/2021] [Indexed: 02/05/2023] Open
Abstract
Reconsolidation has been considered a process in which a consolidated memory is turned into a labile stage. Within the reconsolidation window, the labile memory can be either erased or strengthened. Manipulating acid-sensing ion channels (ASICs) in the amygdala via carbon dioxide (CO2) inhalation enhances memory retrieval and its lability within the reconsolidation window. Moreover, pairing CO2 inhalation with retrieval bears the reactivation of the memory trace and enhances the synaptic exchange of the calcium-impermeable AMPA receptors to calcium-permeable AMPA receptors. Our patch-clamp data suggest that the exchange of the AMPA receptors depends on the ubiquitin-proteasome system (UPS), via protein degradation. Ziram (50 µM), a ubiquitination inhibitor, reduces the turnover of the AMPA receptors. CO2 inhalation with retrieval boosts the ubiquitination without altering the proteasome activity. Several calcium-dependent kinases potentially involved in the CO2-inhalation regulated memory liability were identified using the Kinome assay. These results suggest that the UPS plays a key role in regulating the turnover of AMPA receptors during CO2 inhalation.
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Affiliation(s)
- Boren Lin
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, 38163, Memphis, TN, USA
- Department of Biological Sciences, The University of Toledo, 43606, Toledo, OH, USA
| | - Khaled Alganem
- Department of Neurosciences, The University of Toledo Medical Center, 43614, Toledo, OH, USA
| | - Sinead M O'Donovan
- Department of Neurosciences, The University of Toledo Medical Center, 43614, Toledo, OH, USA
| | - Zhen Jin
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, 38163, Memphis, TN, USA
| | - FarzanehSadat Naghavi
- Department of Neurosciences, The University of Toledo Medical Center, 43614, Toledo, OH, USA
| | - Olivia A Miller
- Department of Biological Sciences, The University of Toledo, 43606, Toledo, OH, USA
| | - Tyler C Ortyl
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, 38163, Memphis, TN, USA
| | - Ye Chun Ruan
- Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China
| | - Robert E McCullumsmith
- Department of Neurosciences, The University of Toledo Medical Center, 43614, Toledo, OH, USA
- Neurosciences Institute, ProMedica, OH, 43614, Toledo, USA
| | - Jianyang Du
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, 38163, Memphis, TN, USA.
- Neuroscience Institute, The University of Tennessee Health Science Center, 38163, Memphis, TN, USA.
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17
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Altered Phosphorylation of the Proteasome Subunit Rpt6 Has Minimal Impact on Synaptic Plasticity and Learning. eNeuro 2021; 8:ENEURO.0073-20.2021. [PMID: 33658307 PMCID: PMC8116113 DOI: 10.1523/eneuro.0073-20.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 01/13/2021] [Accepted: 01/27/2021] [Indexed: 11/21/2022] Open
Abstract
Dynamic control of protein degradation via the ubiquitin proteasome system (UPS) is thought to play a crucial role in neuronal function and synaptic plasticity. The proteasome subunit Rpt6, an AAA ATPase subunit of the 19S regulatory particle (RP), has emerged as an important site for regulation of 26S proteasome function in neurons. Phosphorylation of Rpt6 on serine 120 (S120) can stimulate the catalytic rate of substrate degradation by the 26S proteasome and this site is targeted by the plasticity-related kinase Ca2+/calmodulin-dependent kinase II (CaMKII), making it an attractive candidate for regulation of proteasome function in neurons. Several in vitro studies have shown that altered Rpt6 S120 phosphorylation can affect the structure and function of synapses. To evaluate the importance of Rpt6 S120 phosphorylation in vivo, we created two mouse models which feature mutations at S120 that block or mimic phosphorylation at this site. We find that peptidase and ATPase activities are upregulated in the phospho-mimetic mutant and downregulated in the phospho-dead mutant [S120 mutated to aspartic acid (S120D) or alanine (S120A), respectively]. Surprisingly, these mutations had no effect on basal synaptic transmission, long-term potentiation (LTP), and dendritic spine dynamics and density in the hippocampus. Furthermore, these mutants displayed no deficits in cued and contextual fear memory. Thus, in a mouse model that blocks or mimics phosphorylation at this site, either compensatory mechanisms negate these effects, or small variations in proteasome activity are not enough to induce significant changes in synaptic structure, plasticity, or behavior.
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18
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Dulka BN, Trask S, Helmstetter FJ. Age-Related Memory Impairment and Sex-Specific Alterations in Phosphorylation of the Rpt6 Proteasome Subunit and Polyubiquitination in the Basolateral Amygdala and Medial Prefrontal Cortex. Front Aging Neurosci 2021; 13:656944. [PMID: 33897408 PMCID: PMC8062735 DOI: 10.3389/fnagi.2021.656944] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/15/2021] [Indexed: 12/31/2022] Open
Abstract
Aging is marked by an accumulation of damaged and modified brain proteins, and the ubiquitin-proteasome system (UPS) is important for cellular protein degradation. Recent work has established a critical role for the UPS in memory and synaptic plasticity, but the role of the UPS in age-related cognitive decline remains poorly understood. We trained young, middle-aged, and aged male and female rats using trace fear conditioning (TFC) to investigate the effects of age and sex on memory. We then measured markers of UPS-related protein degradation (phosphorylation of the Rpt6 proteasome regulatory subunit and K48-linked polyubiquitination) using western blots. We found that aged males, but not aged females, showed behavioral deficits at memory retrieval. Aged males also displayed reduced phosphorylation of the Rpt6 proteasome subunit and accumulation of K48 in the basolateral amygdala, while aged females displayed a similar pattern in the medial prefrontal cortex. These findings suggest that markers of UPS function are differentially affected by age and sex in a brain region-dependent manner. Together these results provide an important step toward understanding the UPS and circuit-level differences in aging males and females.
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Affiliation(s)
- Brooke N Dulka
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Sydney Trask
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
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Devulapalli R, Jones N, Farrell K, Musaus M, Kugler H, McFadden T, Orsi SA, Martin K, Nelsen J, Navabpour S, O'Donnell M, McCoig E, Jarome TJ. Males and females differ in the regulation and engagement of, but not requirement for, protein degradation in the amygdala during fear memory formation. Neurobiol Learn Mem 2021; 180:107404. [PMID: 33609735 DOI: 10.1016/j.nlm.2021.107404] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 01/28/2021] [Accepted: 02/10/2021] [Indexed: 02/07/2023]
Abstract
Over the last decade, strong evidence has emerged that protein degradation mediated by the ubiquitin-proteasome system is critical for fear memory formation in the amygdala. However, this work has been done primarily in males, leaving unanswered questions about whether females also require protein degradation during fear memory formation. Here, we found that male and female rats differed in their engagement and regulation of, but not need for, protein degradation in the amygdala during fear memory formation. Male, but not female, rats had increased protein degradation in the nuclei of amygdala cells after fear conditioning. Conversely, females had elevated baseline levels of overall ubiquitin-proteasome activity in amygdala nuclei. Gene expression and DNA methylation analyses identified that females had increased baseline expression of the ubiquitin coding gene Uba52, which had increased DNA 5-hydroxymethylation (5hmc) in its promoter region, indicating a euchromatin state necessary for increased levels of ubiquitin in females. Consistent with this, persistent CRISPR-dCas9 mediated silencing of Uba52 and proteasome subunit Psmd14 in the amygdala reduced baseline protein degradation levels and impaired fear memory in male and female rats, while enhancing baseline protein degradation in the amygdala of both sexes promoted fear memory formation. These results suggest that while both males and females require protein degradation in the amygdala for fear memory formation, they differ in their baseline regulation and engagement of this process following learning. These results have important implications for understanding the etiology of sex-related differences in fear memory formation.
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Affiliation(s)
- Rishi Devulapalli
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Natalie Jones
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Kayla Farrell
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Hannah Kugler
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Taylor McFadden
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Sabrina A Orsi
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Kiley Martin
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Jacob Nelsen
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Shaghayegh Navabpour
- Fralin Biomedical Research Institute, Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | - Madison O'Donnell
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Emmarose McCoig
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Timothy J Jarome
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA; Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA; Fralin Biomedical Research Institute, Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA.
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Analysis of Differentially Expressed Genes in the Dentate Gyrus and Anterior Cingulate Cortex in a Mouse Model of Depression. BIOMED RESEARCH INTERNATIONAL 2021; 2021:5013565. [PMID: 33628784 PMCID: PMC7892236 DOI: 10.1155/2021/5013565] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/11/2020] [Accepted: 01/23/2021] [Indexed: 12/18/2022]
Abstract
Major depressive disorder (MDD) is a prevalent, chronic, and relapse-prone psychiatric disease. However, the intermediate molecules resulting from stress and neurological impairment in different brain regions are still unclear. To clarify the pathological changes in the dentate gyrus (DG) and anterior cingulate cortex (ACC) regions of the MDD brain, which are the most closely related to the disease, we investigated the published microarray profile dataset GSE84183 to identify unpredictable chronic mild stress- (UCMS-) induced differentially expressed genes (DEGs) in the DG and ACC regions. Based on the DEG data, functional annotation, protein-protein interaction, and transcription factor (TF) analyses were performed. In this study, 1071 DEGs (679 upregulated and 392 downregulated) and 410 DEGs (222 upregulated and 188 downregulated) were identified in DG and ACC, respectively. The pathways and GO terms enriched by the DEGs in the DG, such as cell adhesion, proteolysis, ion transport, transmembrane transport, chemical synaptic transmission, immune system processes, response to lipopolysaccharide, and nervous system development, may reveal the molecular mechanism of MDD. However, the DEGs in the ACC involved metabolic processes, proteolysis, visual learning, DNA methylation, innate immune responses, cell migration, and circadian rhythm. Sixteen hub genes in the DG (Fn1, Col1a1, Anxa1, Penk, Ptgs2, Cdh1, Timp1, Vim, Rpl30, Rps21, Dntt, Ptk2b, Jun, Avp, Slit1, and Sema5a) were identified. Eight hub genes in the ACC (Prkcg, Grin1, Syngap1, Rrp9, Grwd1, Pik3r1, Hnrnpc, and Prpf40a) were identified. In addition, eleven TFs (Chd2, Zmiz1, Myb, Etv4, Rela, Tcf4, Tcf12, Chd1, Mef2a, Ubtf, and Mxi1) were predicted to regulate more than two of these hub genes. The expression levels of ten randomly selected hub genes that were specifically differentially expressed in the MDD-like animal model were verified in the corresponding regions in the human brain. These hub genes and TFs may be regarded as potential targets for future MDD treatment strategies, thus aiding in the development of new therapeutic approaches to MDD.
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21
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Expanding the role of proteasome homeostasis in Parkinson's disease: beyond protein breakdown. Cell Death Dis 2021; 12:154. [PMID: 33542205 PMCID: PMC7862491 DOI: 10.1038/s41419-021-03441-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 02/06/2023]
Abstract
Proteasome is the principal hydrolytic machinery responsible for the great majority of protein degradation. The past three decades have testified prominent advances about proteasome involved in almost every aspect of biological processes. Nonetheless, inappropriate increase or decrease in proteasome function is regarded as a causative factor in several diseases. Proteasome abundance and proper assembly need to be precisely controlled. Indeed, various neurodegenerative diseases including Parkinson's disease (PD) share a common pathological feature, intracellular protein accumulation such as α-synuclein. Proteasome activation may effectively remove aggregates and prevent the neurodegeneration in PD, which provides a potential application for disease-modifying treatment. In this review, we build on the valuable discoveries related to different types of proteolysis by distinct forms of proteasome, and how its regulatory and catalytic particles promote protein elimination. Additionally, we summarize the emerging ideas on the proteasome homeostasis regulation by targeting transcriptional, translational, and post-translational levels. Given the imbalanced proteostasis in PD, the strategies for intensifying proteasomal degradation are advocated as a promising approach for PD clinical intervention.
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22
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Kim CH, Kim S, Kim SH, Roh J, Jin H, Song B. Role of densin-180 in mouse ventral hippocampal neurons in 24-hr retention of contextual fear conditioning. Brain Behav 2020; 10:e01891. [PMID: 33064361 PMCID: PMC7749528 DOI: 10.1002/brb3.1891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 09/01/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Densin-180 interacts with postsynaptic molecules including calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) but its function in learning and memory process has been unclear. METHODS To investigate a role of hippocampal densin-180 in contextual fear conditioning (CFC) learning and memory processes, knockdown (KD) of densin-180 in hippocampal subareas was applied. RESULTS First, ventral hippocampal (vHC) densin-180 KD impaired single-trial CFC (stCFC) memory one day later. stCFC caused freezing behaviors to reach the peak about one hour later in both control and KD mice, but then freezing was disappeared at 2 hr postshock in KD mice. Second, stCFC caused an immediate and transient reduction of vHC densin-180 in control mice, which was not observed in KD mice. Third, stCFC caused phosphorylated-T286 (p-T286) CaMKIIα to change similarly to densin-180, but p-T305 CaMKIIα was increased 1 hr later in control mice. In KD mice, these effects were gone. Moreover, both basal levels of p-T286 and p-T305 CaMKIIα were reduced without change in total CaMKIIα in KD mice. Fourth, we found double-trial CFC (dtCFC) memory acquisition and retrieval kinetics were different from those of stCFC in vHC KD mice. In addition, densin-180 in dorsal hippocampal area appeared to play its unique role during the very early retrieval period of both CFC memories. CONCLUSION This study shows that vHC densin-180 is necessary for stCFC memory formation and retrieval and suggests that both densin-180 and p-T305 CaMKIIα at 1 ~ 2 hr postshock are important for stCFC memory formation. We conclude that roles of hippocampal neuronal densin-180 in CFC are temporally dynamic and differential depending on the pattern of conditioning stimuli and its location along the dorsoventral axis of hippocampal formation.
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Affiliation(s)
- Chong-Hyun Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Seoyul Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Su-Hyun Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Jongtae Roh
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Harin Jin
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Bokyung Song
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
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Mishra S, Dunkerly-Eyring BL, Keceli G, Ranek MJ. Phosphorylation Modifications Regulating Cardiac Protein Quality Control Mechanisms. Front Physiol 2020; 11:593585. [PMID: 33281625 PMCID: PMC7689282 DOI: 10.3389/fphys.2020.593585] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 09/28/2020] [Indexed: 12/12/2022] Open
Abstract
Many forms of cardiac disease, including heart failure, present with inadequate protein quality control (PQC). Pathological conditions often involve impaired removal of terminally misfolded proteins. This results in the formation of large protein aggregates, which further reduce cellular viability and cardiac function. Cardiomyocytes have an intricately collaborative PQC system to minimize cellular proteotoxicity. Increased expression of chaperones or enhanced clearance of misfolded proteins either by the proteasome or lysosome has been demonstrated to attenuate disease pathogenesis, whereas reduced PQC exacerbates pathogenesis. Recent studies have revealed that phosphorylation of key proteins has a potent regulatory role, both promoting and hindering the PQC machinery. This review highlights the recent advances in phosphorylations regulating PQC, the impact in cardiac pathology, and the therapeutic opportunities presented by harnessing these modifications.
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Affiliation(s)
- Sumita Mishra
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Brittany L Dunkerly-Eyring
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Gizem Keceli
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Mark J Ranek
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Musaus M, Navabpour S, Jarome TJ. The diversity of linkage-specific polyubiquitin chains and their role in synaptic plasticity and memory formation. Neurobiol Learn Mem 2020; 174:107286. [PMID: 32745599 DOI: 10.1016/j.nlm.2020.107286] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/15/2020] [Accepted: 07/28/2020] [Indexed: 12/12/2022]
Abstract
Over the last 20 years, a number of studies have provided strong support for protein degradation mediated by the ubiquitin-proteasome system in synaptic plasticity and memory formation. In this system, target substrates become covalently modified by the small protein ubiquitin through a series of enzymatic reactions involving hundreds of different ligases. While some substrates will acquire only a single ubiquitin, most will be marked by multiple ubiquitin modifications, which link together at specific lysine sites or the N-terminal methionine on the previous ubiquitin to form a polyubiquitin chain. There are at least eight known linkage-specific polyubiquitin chains a target protein can acquire, many of which are independent of the proteasome, and these chains can be homogenous, mixed, or branched in nature, all of which result in different functional outcomes and fates for the target substrate. However, as the focus has remained on protein degradation, much remains unknown about the role of these diverse ubiquitin chains in the brain, particularly during activity- and learning-dependent synaptic plasticity. Here, we review the different types and functions of ubiquitin chains and summarize evidence suggesting a role for these diverse ubiquitin modifications in synaptic plasticity and memory formation. We conclude by discussing how technological limitations have limited our ability to identify and elucidate the role of different ubiquitin chains in the brain and speculate on the future directions and implications of understanding linkage-specific ubiquitin modifications in activity- and learning-dependent synaptic plasticity.
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Affiliation(s)
- Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Shaghayegh Navabpour
- Fralin Biomedical Research Institute, Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | - Timothy J Jarome
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA; Fralin Biomedical Research Institute, Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA; Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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25
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Dysregulation of protein degradation in the hippocampus is associated with impaired spatial memory during the development of obesity. Behav Brain Res 2020; 393:112787. [PMID: 32603798 DOI: 10.1016/j.bbr.2020.112787] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/26/2020] [Accepted: 06/21/2020] [Indexed: 01/09/2023]
Abstract
Studies have shown that long-term exposure to high fat and other obesogenic diets results in insulin resistance and altered blood brain barrier permeability, dysregulation of intracellular signaling mechanisms, changes in DNA methylation levels and gene expression, and increased oxidative stress and neuroinflammation in the hippocampus, all of which are associated with impaired spatial memory. The ubiquitin-proteasome system controls the majority of protein degradation in cells and is a critical regulator of synaptic plasticity and memory formation. Yet, whether protein degradation in the hippocampus becomes dysregulated following weight gain and is associated with obesity-induced memory impairments is unknown. Here, we used a high fat diet procedure in combination with behavioral and subcellular fractionation protocols and a variety of biochemical assays to determine if ubiquitin-proteasome activity becomes altered in the hippocampus during obesity development and whether this is associated with impaired spatial memory. We found that only 6 weeks of exposure to a high fat diet was sufficient to impair performance on an object location task in rats and resulted in dynamic dysregulation of ubiquitin-proteasome activity in the nucleus and cytoplasm of cells in the hippocampus. Furthermore, these changes in the protein degradation process extended into cortical regions also involved in spatial memory formation. Collectively, these results indicate that weight gain-induced memory impairments may be due to altered ubiquitin-proteasome signaling that occurs during the early stages of obesity development.
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26
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SAK3 Administration Improves Spine Abnormalities and Cognitive Deficits in App NL-G-F/NL-G-F Knock-in Mice by Increasing Proteasome Activity through CaMKII/Rpt6 Signaling. Int J Mol Sci 2020; 21:ijms21113833. [PMID: 32481611 PMCID: PMC7312612 DOI: 10.3390/ijms21113833] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/18/2020] [Accepted: 05/26/2020] [Indexed: 12/11/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia and is characterized by neuropathological hallmarks consisting of accumulation of extracellular amyloid-β (Aβ) plaques and intracellular neurofibrillary tangles (NFT). Recently, we have identified a new AD therapeutic candidate, ethyl-8'-methyl-2',4-dioxo-2-(piperidin-1-yl)-2'H-spiro[cyclopentane-1,3'-imidazo [1,2-a] pyridin]-2-ene-3-carboxylate (SAK3), which ameliorates the AD-like pathology in AppNL-F/NL-F knock-in mice. However, the detailed mechanism underlying the therapeutic effects of SAK3 remains unclear. In this study, we found that SAK3 administration improved the reduced proteasome activity through the activation of CaMKII/Rpt6 signaling in AppNL-F/NL-F knock-in (NL-G-F) mice. Moreover, spine abnormalities observed in NL-G-F mice were significantly reversed by SAK3 administration. Along with this, cognitive impairments found in NL-G-F mice were markedly ameliorated by SAK3. In summary, our data suggest that SAK3 administration increases the activity of the proteasome via activation of the CaMKII/Rpt6 signaling pathway, contributing to improvements in spine abnormalities and cognitive deficits in NL-G-F mice. Overall, our findings suggest that SAK3 might be a new attractive drug candidate, representing a new mechanism for the treatment of AD pathology.
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Molecular Mechanisms in Hippocampus Involved on Object Recognition Memory Consolidation and Reconsolidation. Neuroscience 2020; 435:112-123. [PMID: 32272151 DOI: 10.1016/j.neuroscience.2020.03.047] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 03/01/2020] [Accepted: 03/31/2020] [Indexed: 11/20/2022]
Abstract
Acquired information is stabilized into long-term memory through a process known as consolidation. Though, after consolidation, when stored information is retrieved they can be again susceptible, allowing modification, updating and strengthening and to be re-stabilized they need a new process referred to as memory reconsolidation. However, the molecular mechanisms of recognition memory consolidation and reconsolidation are not fully understood. Also, considering that the study of the link between synaptic proteins is key to understanding of memory processes, we investigated, in male Wistar rats, molecular mechanisms in the hippocampus involved on object recognition memory (ORM) consolidation and reconsolidation. We verified that the blockade of AMPA receptors (AMPAr) and L-VDCCs calcium channels impaired ORM consolidation and reconsolidation when administered into CA1 immediately after sample phase or reactivation phase and that these impairments were blocked by the administration of AMPAr agonist and of neurotrophin BDNF. Also, the blockade of CaMKII impaired ORM consolidation when administered 3 h after sample phase but had no effect on ORM reconsolidation and its effect was blocked by the administration of BDNF, but not of AMPAr agonist. So, this study provides new evidence of the molecular mechanisms involved on the consolidation and reconsolidation of ORM, demonstrating that AMPAr and L-VDCCs are necessary for the consolidation and reconsolidation of ORM while CaMKII is necessary only for the consolidation and also that there is a link between BDNF and AMPAr, L-VDCCs and CaMKII as well as a link between AMPAr and L-VDCCs on ORM consolidation and reconsolidation.
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28
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Dulka BN, Pullins SE, Cullen PK, Moyer JR, Helmstetter FJ. Age-related memory deficits are associated with changes in protein degradation in brain regions critical for trace fear conditioning. Neurobiol Aging 2020; 91:160-166. [PMID: 32280031 DOI: 10.1016/j.neurobiolaging.2020.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 01/23/2020] [Accepted: 03/02/2020] [Indexed: 12/25/2022]
Abstract
Brain aging is accompanied by an accumulation of damaged proteins, which results from deterioration of cellular quality control mechanisms and decreased protein degradation. The ubiquitin-proteasome system (UPS) is the primary proteolytic mechanism responsible for targeted degradation. Recent work has established a critical role of the UPS in memory and synaptic plasticity, but the role of the UPS in age-related cognitive decline remains poorly understood. Here, we measured markers of UPS function and related them to fear memory in rats. Our results show that age-related memory deficits are associated with reductions in phosphorylation of the Rpt6 proteasome regulatory subunit and corresponding increases in lysine-48 (K48)-linked ubiquitin tagging within the basolateral amygdala. Increases in K48 polyubiquitination were also observed in the medial prefrontal cortex and dorsal hippocampus. These data suggest that protein degradation is a critical component of age-related memory deficits. This extends our understanding of the relationship between the UPS, aging, and memory, which is an important step toward the prevention and treatment of deficits associated with normal cognitive aging and memory-related neurodegenerative diseases.
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Affiliation(s)
- Brooke N Dulka
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Shane E Pullins
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Patrick K Cullen
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - James R Moyer
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
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29
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CaMKII/proteasome/cytosolic calcium/cathepsin B axis was present in tryspin activation induced by nicardipine. Biosci Rep 2019; 39:BSR20190516. [PMID: 31221819 PMCID: PMC6603279 DOI: 10.1042/bsr20190516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 06/14/2019] [Accepted: 06/19/2019] [Indexed: 12/16/2022] Open
Abstract
Premature trypsinogen activation is the early event of acute pancreatitis. Therefore, the studies on the processes of trypsinogen activation induced by compounds are important to understand mechanism underly acute pancreatitis under various conditions. Calcium overload in the early stage of acute pancreatitis was previously found to cause intracellular trypsinogen activation; however, treatment of acute pancreatitis using calcium channel blockers did not produced consistent results. Proteasome activity that could be inhibited by some calcium channel blocker has recently been reported to affect the development of acute pancreatitis; however, the associated mechanism were not fully understood. Here, the roles of nicardipine were investigated in trypsinogen activation in pancreatic acinar cells. The results showed that nicardipine could increase cathepsin B activity that caused trypsinogen activation, but higher concentration of nicardipine or prolonged treatment had an opposite effect. The effects of short time treatment of nicardipine at low concentration were studied here. Proteasome inhibition was observed under nicardipine treatment that contributed to the up-regulation in cytosolic calcium. Increased cytosolic calcium from ER induced by nicardipine resulted in the release and activation of cathepsin B. Meanwhile, calcium chelator inhibited cathepsin B as well as trypsinogen activation. Consistently, proteasome activator protected acinar cells from injury induced by nicardipine. Moreover, proteasome inhibition caused by nicardipine depended on CaMKII. In conclusion, CaMKII down-regulation/proteasome inhibition/cytosolic calcium up-regulation/cathepsin B activation/trypsinogen activation axis was present in pancreatic acinar cells injury under nicardipine treatment.
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30
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Kors S, Geijtenbeek K, Reits E, Schipper-Krom S. Regulation of Proteasome Activity by (Post-)transcriptional Mechanisms. Front Mol Biosci 2019; 6:48. [PMID: 31380390 PMCID: PMC6646590 DOI: 10.3389/fmolb.2019.00048] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/11/2019] [Indexed: 12/23/2022] Open
Abstract
Intracellular protein synthesis, folding, and degradation are tightly controlled processes to ensure proper protein homeostasis. The proteasome is responsible for the degradation of the majority of intracellular proteins, which are often targeted for degradation via polyubiquitination. However, the degradation rate of proteins is also affected by the capacity of proteasomes to recognize and degrade these substrate proteins. This capacity is regulated by a variety of proteasome modulations including (1) changes in complex composition, (2) post-translational modifications, and (3) altered transcription of proteasomal subunits and activators. Various diseases are linked to proteasome modulation and altered proteasome function. A better understanding of these modulations may offer new perspectives for therapeutic intervention. Here we present an overview of these three proteasome modulating mechanisms to give better insight into the diversity of proteasomes.
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Affiliation(s)
- Suzan Kors
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Karlijne Geijtenbeek
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Eric Reits
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Sabine Schipper-Krom
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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31
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Adelöf J, Andersson M, Porritt M, Petersen A, Zetterberg M, Wiseman J, Hernebring M. PA28αβ overexpression enhances learning and memory of female mice without inducing 20S proteasome activity. BMC Neurosci 2018; 19:70. [PMID: 30400847 PMCID: PMC6218978 DOI: 10.1186/s12868-018-0468-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 10/27/2018] [Indexed: 11/16/2022] Open
Abstract
Background The proteasome system plays an important role in synaptic plasticity. Induction and maintenance of long term potentiation is directly dependent on selective targeting of proteins for proteasomal degradation. The 20S proteasome activator PA28αβ activates hydrolysis of small nonubiquitinated peptides and possesses protective functions upon oxidative stress and proteinopathy. The effect of PA28αβ activity on behavior and memory function is, however, not known. We generated a mouse model that overexpresses PA28α (PA28αOE) to understand PA28αβ function during healthy adult homeostasis via assessment of physiological and behavioral profiles, focusing on female mice. Results PA28α and PA28β protein levels were markedly increased in all PA28αOE tissues analyzed. PA28αOE displayed reduced depressive-like behavior in the forced swim test and improved memory/learning function assessed by intersession habituation in activity box and shuttle box passive avoidance test, with no significant differences in anxiety or general locomotor activity. Nor were there any differences found when compared to WT for body composition or immuno-profile. The cognitive effects of PA28αOE were female specific, but could not be explained by alterations in estrogen serum levels or hippocampal regulation of estrogen receptor β. Further, there were no differences in hippocampal protein expression of neuronal or synaptic markers between PA28αOE and WT. Biochemical analysis of hippocampal extracts demonstrated that PA28α overexpression did not increase PA28–20S peptidase activity or decrease K48-polyubiquitin levels. Instead, PA28αOE exhibited elevated efficiency in preventing aggregation in the hippocampus. Conclusions This study reveals, for the first time, a connection between PA28αβ and neuronal function. We found that PA28α overexpressing female mice displayed reduced depressive-like behavior and enhanced learning and memory. Since the positive effects of PA28α overexpression arose without an activation of 20S proteasome capacity, they are likely independent of PA28αβ’s role as a 20S proteasome activator and instead depend on a recognized chaperone-like function. These findings suggest that proteostasis in synaptic plasticity is more diverse than previously reported, and demonstrates a novel function of PA28αβ in the brain. Electronic supplementary material The online version of this article (10.1186/s12868-018-0468-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Julia Adelöf
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.,IMED Biotech Unit, Discovery Biology, Discovery Sciences, AstraZeneca, Gothenburg, Sweden
| | - My Andersson
- Department of Clinical Sciences, Epilepsy Centre, Lund University, Lund, Sweden
| | - Michelle Porritt
- IMED Biotech Unit, Discovery Biology, Discovery Sciences, AstraZeneca, Gothenburg, Sweden
| | - Anne Petersen
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Madeleine Zetterberg
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - John Wiseman
- IMED Biotech Unit, Discovery Biology, Discovery Sciences, AstraZeneca, Gothenburg, Sweden
| | - Malin Hernebring
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden. .,IMED Biotech Unit, Discovery Biology, Discovery Sciences, AstraZeneca, Gothenburg, Sweden.
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32
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Morozov AV, Karpov VL. Biological consequences of structural and functional proteasome diversity. Heliyon 2018; 4:e00894. [PMID: 30417153 PMCID: PMC6218844 DOI: 10.1016/j.heliyon.2018.e00894] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/25/2018] [Accepted: 10/24/2018] [Indexed: 12/21/2022] Open
Abstract
Cell homeostasis and regulation of metabolic pathways are ensured by synthesis, proper folding and efficient degradation of a vast amount of proteins. Ubiquitin-proteasome system (UPS) degrades most intracellular proteins and thus, participates in regulation of cellular metabolism. Within the UPS, proteasomes are the elements that perform substrate cleavage. However, the proteasomes in the organism are diverse. Structurally different proteasomes are present not only in different types of cells, but also in a single cell. The reason for proteasome heterogeneity is not fully understood. This review briefly encompasses mammalian proteasome structure and function, and discusses biological relevance of proteasome diversity for a range of important cellular functions including internal and external signaling.
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Affiliation(s)
- Alexey V Morozov
- W.A. Engelhardt Institute of Molecular Biology, RAS, 119991, Moscow, Russia
| | - Vadim L Karpov
- W.A. Engelhardt Institute of Molecular Biology, RAS, 119991, Moscow, Russia
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33
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Vigil FA, Giese KP. Calcium/calmodulin-dependent kinase II and memory destabilization: a new role in memory maintenance. J Neurochem 2018; 147:12-23. [PMID: 29704430 PMCID: PMC6221169 DOI: 10.1111/jnc.14454] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/28/2018] [Accepted: 04/17/2018] [Indexed: 02/03/2023]
Abstract
In this review, we discuss the poorly explored role of calcium/calmodulin-dependent protein kinase II (CaMKII) in memory maintenance, and its influence on memory destabilization. After a brief review on CaMKII and memory destabilization, we present critical pieces of evidence suggesting that CaMKII activity increases retrieval-induced memory destabilization. We then proceed to propose two potential molecular pathways to explain the association between CaMKII activation and increased memory destabilization. This review will pinpoint gaps in our knowledge and discuss some 'controversial' observations, establishing the basis for new experiments on the role of CaMKII in memory reconsolidation. The role of CaMKII in memory destabilization is of great clinical relevance. Still, because of the lack of scientific literature on the subject, more basic science research is necessary to pursue this pathway as a clinical tool.
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Affiliation(s)
- Fabio Antonio Vigil
- Department of Cell and Integrative PhysiologyThe University of Texas Health San Antonio8403, Floyd Curl DriveSan AntonioTX 78229USA
| | - Karl Peter Giese
- Department of Basic and Clinical NeuroscienceKing's College London125 Coldharbour LaneLondonSE5 9NUUK
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34
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Effects of CREB1 gene silencing on cognitive dysfunction by mediating PKA-CREB signaling pathway in mice with vascular dementia. Mol Med 2018; 24:18. [PMID: 30134805 PMCID: PMC6016877 DOI: 10.1186/s10020-018-0020-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 04/20/2018] [Indexed: 12/22/2022] Open
Abstract
Background As a form of dementia primarily affecting the elderly, vascular dementia (VD) is characterized by changes in the supply of blood to the brain, resulting in cognitive impairment. The aim of the present study was to explore the effects involved with cyclic adenosine monophosphate (cAMP) response element-binding (CREB)1 gene silencing on cognitive dysfunction through meditation of the protein kinase A (PKA)-CREB signaling pathway in mice with VD. Methods Both the Morris water maze test and the step down test were applied to assess the cognitive function of the mice with VD. Immunohistochemical and TUNEL staining techniques were employed to evaluate the positive expression rates of the protein CREB1 and Cleaved Caspase-3, as well as neuronal apoptosis among hippocampal tissues in a respective manner. Flow cytometry was applied to determine the proliferation index and apoptosis rate of the hippocampal cells among each group. Reverse transcription quantitative polymerase chain reaction and Western blot analysis methods were applied to detect the expressions of cAMP, PKA and CREB in hippocampal cells. Results Compared with the normal group, all the other groups exhibited impaired cognitive function, reduced cell numbers in the CAI area, positive expressions of CREB1 as well as positive optical density (OD) values. Furthermore, increased Cleaved Caspase-3 positive expression, OD value, proliferation index, apoptosis rate of hippocampal cells and neurons, were observed in the other groups when compared with the normal group, as well as lower expressions of cAMP, PKA and CREB1 and p-CREB1 (the shCREB1–1, H89 and shCREB1–1 + H89 groups < the VD group). Conclusion The key findings of the present study demonstrated that CREB1 gene silencing results in aggravated VD that occurs as a result of inhibiting the PKA-CREB signaling pathway, thus exasperating cognitive dysfunction.
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35
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Alghamdi A, Vallortigara J, Howlett DR, Broadstock M, Hortobágyi T, Ballard C, Thomas AJ, O'Brien JT, Aarsland D, Attems J, Francis PT, Whitfield DR. Reduction of RPT6/S8 (a Proteasome Component) and Proteasome Activity in the Cortex is Associated with Cognitive Impairment in Lewy Body Dementia. J Alzheimers Dis 2018; 57:373-386. [PMID: 28269775 PMCID: PMC5438478 DOI: 10.3233/jad-160946] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Lewy body dementia is the second most common neurodegenerative dementia and is pathologically characterized by α-synuclein positive cytoplasmic inclusions, with varying amounts of amyloid-β (Aβ) and hyperphosphorylated tau (tau) aggregates in addition to synaptic loss. A dysfunctional ubiquitin proteasome system (UPS), the major proteolytic pathway responsible for the clearance of short lived proteins, may be a mediating factor of disease progression and of the development of α-synuclein aggregates. In the present study, protein expression of a key component of the UPS, the RPT6 subunit of the 19S regulatory complex was determined. Furthermore, the main proteolytic-like (chymotrypsin- and PGPH-) activities have also been analyzed. The middle frontal (Brodmann, BA9), inferior parietal (BA40), and anterior cingulate (BA24) gyrus' cortex were selected as regions of interest from Parkinson's disease dementia (PDD, n = 31), dementia with Lewy bodies (DLB, n = 44), Alzheimer's disease (AD, n = 16), and control (n = 24) brains. Clinical and pathological data available included the MMSE score. DLB, PDD, and AD were characterized by significant reductions of RPT6 (one-way ANOVA, p < 0.001; Bonferroni post hoc test) in prefrontal cortex and parietal cortex compared with controls. Strong associations were observed between RPT6 levels in prefrontal, parietal cortex, and anterior cingulate gyrus and cognitive impairment (p = 0.001, p = 0.001, and p = 0.008, respectively). These findings highlight the involvement of the UPS in Lewy body dementia and indicate that targeting the UPS may have the potential to slow down or reduce the progression of cognitive impairment in DLB and PDD.
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Affiliation(s)
- Amani Alghamdi
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK.,Department of Biochemistry, King Saud University, College of Science, Riyadh, Saudi Arabia
| | - Julie Vallortigara
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - David R Howlett
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - Martin Broadstock
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - Tibor Hortobágyi
- Department of Neuropathology, Institute of Pathology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Clive Ballard
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK.,University of Exeter Medical School, University of Exeter, Devon, UK
| | - Alan J Thomas
- NIHR Biomedical Research Centre for Mental Health, South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, UK
| | | | - Dag Aarsland
- Department of Neurobiology, Ward Sciences and Society, Karolinska Institute, Stockholm Sweden.,Centre for Age-Related Medicine, Stavanger University Hospital, Stavanger, Norway
| | - Johannes Attems
- Institute of Neuroscience and Newcastle University Institute for Ageing, Campus for Ageing and Vitality, UK
| | - Paul T Francis
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - David R Whitfield
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
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36
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Myeku N, Duff KE. Targeting the 26S Proteasome To Protect Against Proteotoxic Diseases. Trends Mol Med 2017; 24:18-29. [PMID: 29233753 DOI: 10.1016/j.molmed.2017.11.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/21/2017] [Accepted: 11/21/2017] [Indexed: 12/16/2022]
Abstract
Aggregates of misfolded proteins can compromise the function of the 26S proteasome complex, leaving neurons susceptible to accelerated and impaired protein homeostasis, thereby contributing to the pathogenesis of neurodegeneration. Strategies aimed at enhancing the function of the 26S proteasome via phosphorylation of key subunit epitopes have been effective in reducing protein aggregates in mouse models of disease. We discuss how phosphodiesterase (PDE) inhibitors and G protein-coupled receptor (GPCR)-targeted drugs might be considered as candidate therapeutics, acting on second messenger signal transduction. The range of candidates might address the need for region-, cell-, or even cellular compartment-specific modulation. Given the array of clinical and experimental drugs targeting cAMP/cGMP signaling, we propose that proteasome activators targeting secondary messengers might be exploited as novel agents for the treatment or prevention of some neurodegenerative diseases.
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Affiliation(s)
- Natura Myeku
- Department of Pathology and Cell Biology, The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
| | - Karen E Duff
- Department of Pathology and Cell Biology, The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, NY, USA.
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Cullen PK, Ferrara NC, Pullins SE, Helmstetter FJ. Context memory formation requires activity-dependent protein degradation in the hippocampus. ACTA ACUST UNITED AC 2017; 24:589-596. [PMID: 29038220 PMCID: PMC5647928 DOI: 10.1101/lm.045443.117] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 08/09/2017] [Indexed: 01/10/2023]
Abstract
Numerous studies have indicated that the consolidation of contextual fear memories supported by an aversive outcome like footshock requires de novo protein synthesis as well as protein degradation mediated by the ubiquitin-proteasome system (UPS). Context memory formed in the absence of an aversive stimulus by simple exposure to a novel environment requires de novo protein synthesis in both the dorsal (dHPC) and ventral (vHPC) hippocampus. However, the role of UPS-mediated protein degradation in the consolidation of context memory in the absence of a strong aversive stimulus has not been investigated. In the present study, we used the context preexposure facilitation effect (CPFE) procedure, which allows for the dissociation of context learning from context-shock learning, to investigate the role of activity-dependent protein degradation in the dHPC and vHPC during the formation of a context memory. We report that blocking protein degradation with the proteasome inhibitor clasto-lactacystin β-lactone (βLac) or blocking protein synthesis with anisomycin (ANI) immediately after context preexposure significantly impaired context memory formation. Additionally, we examined 20S proteasome activity at different time points following context exposure and saw that the activity of proteasomes in the dHPC increases immediately after stimulus exposure while the vHPC exhibits a biphasic pattern of proteolytic activity. Taken together, these data suggest that the requirement of increased proteolysis during memory consolidation is not driven by processes triggered by the strong aversive outcome (i.e., shock) normally used to support fear conditioning.
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Affiliation(s)
- Patrick K Cullen
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
| | - Nicole C Ferrara
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
| | - Shane E Pullins
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
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Regulating protein breakdown through proteasome phosphorylation. Biochem J 2017; 474:3355-3371. [PMID: 28947610 DOI: 10.1042/bcj20160809] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/28/2017] [Accepted: 08/30/2017] [Indexed: 12/31/2022]
Abstract
The ubiquitin proteasome system degrades the great majority of proteins in mammalian cells. Countless studies have described how ubiquitination promotes the selective degradation of different cell proteins. However, there is a small but the growing literature that protein half-lives can also be regulated by post-translational modifications of the 26S proteasome. The present study reviews the ability of several kinases to alter proteasome function through subunit phosphorylation. For example, PKA (protein kinase A) and DYRK2 (dual-specificity tyrosine-regulated kinase 2) stimulate the proteasome's ability to degrade ubiquitinated proteins, peptides, and adenosine triphosphate, while one kinase, ASK1 (apoptosis signal-regulating kinase 1), inhibits proteasome function during apoptosis. Proteasome phosphorylation is likely to be important in regulating protein degradation because it occurs downstream from many hormones and neurotransmitters, in conditions that raise cyclic adenosine monophosphate or cyclic guanosine monophosphate levels, after calcium influx following synaptic depolarization, and during phases of the cell cycle. Beyond its physiological importance, pharmacological manipulation of proteasome phosphorylation has the potential to combat various diseases. Inhibitors of phosphodiesterases by activating PKA or PKG (protein kinase G) can stimulate proteasomal degradation of misfolded proteins that cause neurodegenerative or myocardial diseases and even reduce the associated pathology in mouse models. These observations are promising since in many proteotoxic diseases, aggregation-prone proteins impair proteasome function, and disrupt protein homeostasis. Conversely, preventing subunit phosphorylation by DYRK2 slows cell cycle progression and tumor growth. However, further research is essential to determine how phosphorylation of different subunits by these (or other) kinases alters the properties of this complex molecular machine and thus influence protein degradation rates.
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Guo X, Huang X, Chen MJ. Reversible phosphorylation of the 26S proteasome. Protein Cell 2017; 8:255-272. [PMID: 28258412 PMCID: PMC5359188 DOI: 10.1007/s13238-017-0382-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/26/2017] [Indexed: 01/09/2023] Open
Abstract
The 26S proteasome at the center of the ubiquitin-proteasome system (UPS) is essential for virtually all cellular processes of eukaryotes. A common misconception about the proteasome is that, once made, it remains as a static and uniform complex with spontaneous and constitutive activity for protein degradation. Recent discoveries have provided compelling evidence to support the exact opposite insomuch as the 26S proteasome undergoes dynamic and reversible phosphorylation under a variety of physiopathological conditions. In this review, we summarize the history and current understanding of proteasome phosphorylation, and advocate the idea of targeting proteasome kinases/phosphatases as a new strategy for clinical interventions of several human diseases.
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Affiliation(s)
- Xing Guo
- The Life Sciences Institute of Zhejiang University, Hangzhou, 310058, China.
| | - Xiuliang Huang
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Mark J Chen
- Department of Bioinformatics and Computational Biology, Genentech Inc., South San Francisco, CA, 94080, USA
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40
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Subnormothermic Perfusion in the Isolated Rat Liver Preserves the Antioxidant Glutathione and Enhances the Function of the Ubiquitin Proteasome System. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:9324692. [PMID: 27800122 PMCID: PMC5075307 DOI: 10.1155/2016/9324692] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/09/2016] [Accepted: 09/15/2016] [Indexed: 12/18/2022]
Abstract
The reduction of oxidative stress is suggested to be one of the main mechanisms to explain the benefits of subnormothermic perfusion against ischemic liver damage. In this study we investigated the early cellular mechanisms induced in isolated rat livers after 15 min perfusion at temperatures ranging from normothermia (37°C) to subnormothermia (26°C and 22°C). Subnormothermic perfusion was found to maintain hepatic viability. Perfusion at 22°C raised reduced glutathione levels and the activity of glutathione reductase; however, lipid and protein oxidation still occurred as determined by malondialdehyde, 4-hydroxynonenal-protein adducts, and advanced oxidation protein products. In livers perfused at 22°C the lysosomal and ubiquitin proteasome system (UPS) were both activated. The 26S chymotrypsin-like (β5) proteasome activity was significantly increased in the 26°C (46%) and 22°C (42%) groups. The increased proteasome activity may be due to increased Rpt6 Ser120 phosphorylation, which is known to enhance 26S proteasome activity. Together, our results indicate that the early events produced by subnormothermic perfusion in the liver can induce oxidative stress concomitantly with antioxidant glutathione preservation and enhanced function of the lysosomal and UPS systems. Thus, a brief hypothermia could trigger antioxidant mechanisms and may be functioning as a preconditioning stimulus.
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41
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Mayor T, Sharon M, Glickman MH. Tuning the proteasome to brighten the end of the journey. Am J Physiol Cell Physiol 2016; 311:C793-C804. [PMID: 27605452 DOI: 10.1152/ajpcell.00198.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/04/2016] [Indexed: 02/07/2023]
Abstract
Degradation by the proteasome is the fate for a large portion of cellular proteins, and it plays a major role in maintaining protein homeostasis, as well as in regulating many cellular processes like cell cycle progression. A decrease in proteasome activity has been linked to aging and several age-related neurodegenerative pathologies and highlights the importance of the ubiquitin proteasome system regulation. While the proteasome has been traditionally viewed as a constitutive element of proteolysis, major studies have highlighted how different regulatory mechanisms can impact its activity. Importantly, alterations of proteasomal activity may have major impacts for its function and in therapeutics. On one hand, increasing proteasome activity could be beneficial to prevent the age-related downfall of protein homeostasis, whereas inhibiting or reducing its activity can prevent the proliferation of cancer cells.
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Affiliation(s)
- Thibault Mayor
- Department of Biochemistry and Molecular Biology, Michael Smith Laboratories, University of British Columbia, Vancouver, Canada;
| | - Michal Sharon
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel; and
| | - Michael H Glickman
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
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42
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Hegde AN. Proteolysis, synaptic plasticity and memory. Neurobiol Learn Mem 2016; 138:98-110. [PMID: 27614141 DOI: 10.1016/j.nlm.2016.09.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 08/25/2016] [Accepted: 09/05/2016] [Indexed: 12/30/2022]
Abstract
Protein degradation has many critical functions in the nervous system such as refinement of synaptic connections during development and synaptic plasticity and memory in the adult organisms. A major cellular machinery of proteolysis is the ubiquitin-proteasome pathway (UPP). The UPP precisely regulates proteolysis by covalently attaching ubiquitin, a small protein, to substrates through sequential enzymatic reactions and the proteins marked with the ubiquitin tag are degraded by complex containing many subunits called the proteasome. Research over the years has shown a role for the UPP in regulating presynaptic and postsynaptic proteins critical for neurotransmission and synaptic plasticity. Studies have also revealed a role for the UPP in various forms of memory. Mechanistic investigations suggest that the function of the UPP in neurons is not homogenous and is subject to local regulation in different neuronal sub-compartments. In both invertebrate and vertebrate model systems, local roles have been found for enzymes that attach ubiquitin to substrate proteins as well as for enzymes that remove ubiquitin from substrates. The proteasome also has disparate functions in different parts of the neuron. In addition to the UPP, proteolysis by the lysosome and autophagy play a role in synaptic plasticity and memory. This review details the functions of proteolysis in synaptic plasticity and summarizes the findings on the connection between proteolysis and memory mainly focusing on the UPP including its local roles.
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Affiliation(s)
- Ashok N Hegde
- Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, GA 31061, USA.
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43
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CaMKII regulates proteasome phosphorylation and activity and promotes memory destabilization following retrieval. Neurobiol Learn Mem 2016; 128:103-9. [PMID: 26779588 DOI: 10.1016/j.nlm.2016.01.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/30/2015] [Accepted: 01/05/2016] [Indexed: 01/04/2023]
Abstract
Numerous studies have suggested that memories "destabilize" and require de novo protein synthesis in order to reconsolidate following retrieval, but very little is known about how this destabilization process is regulated. Recently, ubiquitin-proteasome mediated protein degradation has been identified as a critical regulator of memory trace destabilization following retrieval, though the specific mechanisms controlling retrieval-induced changes in ubiquitin-proteasome activity remain equivocal. Here, we found that proteasome activity is increased in the amygdala in a CaMKII-dependent manner following the retrieval of a contextual fear memory. We show that in vitro inhibition of CaMKII reversed retrieval-induced increases in proteasome activity. Additionally, in vivo pharmacological blockade of CaMKII abolished increases in proteolytic activity and activity related regulatory phosphorylation in the amygdala following retrieval, suggesting that CaMKII was "upstream" of protein degradation during the memory reconsolidation process. Consistent with this, while inhibiting CaMKII in the amygdala did not impair memory following retrieval, it completely attenuated the memory impairments that resulted from post-retrieval protein synthesis blockade. Collectively, these results suggest that CaMKII controls the initiation of the memory reconsolidation process through regulation of the proteasome.
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44
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Werner CT, Milovanovic M, Christian DT, Loweth JA, Wolf ME. Response of the Ubiquitin-Proteasome System to Memory Retrieval After Extended-Access Cocaine or Saline Self-Administration. Neuropsychopharmacology 2015; 40:3006-14. [PMID: 26044907 PMCID: PMC4864635 DOI: 10.1038/npp.2015.156] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 05/08/2015] [Accepted: 05/26/2015] [Indexed: 01/24/2023]
Abstract
The ubiquitin-proteasome system (UPS) has been implicated in the retrieval-induced destabilization of cocaine- and fear-related memories in Pavlovian paradigms. However, nothing is known about its role in memory retrieval after self-administration of cocaine, an operant paradigm, or how the length of withdrawal from cocaine may influence retrieval mechanisms. Here, we examined UPS activity after an extended-access cocaine self-administration regimen that leads to withdrawal-dependent incubation of cue-induced cocaine craving. Controls self-administered saline. In initial experiments, memory retrieval was elicited via a cue-induced seeking/retrieval test on withdrawal day (WD) 50-60, when craving has incubated. We found that retrieval of cocaine- and saline-associated memories produced similar increases in polyubiquitinated proteins in the nucleus accumbens (NAc), compared with rats that did not undergo a seeking/retrieval test. Measures of proteasome catalytic activity confirmed similar activation of the UPS after retrieval of saline and cocaine memories. However, in a subsequent experiment in which testing was conducted on WD1, proteasome activity in the NAc was greater after retrieval of cocaine memory than saline memory. Analysis of other brain regions confirmed that effects of cocaine memory retrieval on proteasome activity, relative to saline memory retrieval, depend on withdrawal time. These results, combined with prior studies, suggest that the relationship between UPS activity and memory retrieval depends on training paradigm, brain region, and time elapsed between training and retrieval. The observation that mechanisms underlying cocaine memory retrieval change depending on the age of the memory has implications for development of memory destabilization therapies for cue-induced relapse in cocaine addicts.
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Affiliation(s)
- Craig T Werner
- Department of Neuroscience, Chicago Medical School at Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Mike Milovanovic
- Department of Neuroscience, Chicago Medical School at Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Daniel T Christian
- Department of Neuroscience, Chicago Medical School at Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Jessica A Loweth
- Department of Neuroscience, Chicago Medical School at Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Marina E Wolf
- Department of Neuroscience, Chicago Medical School at Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA,Department of Neuroscience, Chicago Medical School at Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA, Tel: +847 578 8659, Fax: +847 578 8515, E-mail
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45
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Jarome TJ, Ferrara NC, Kwapis JL, Helmstetter FJ. Contextual Information Drives the Reconsolidation-Dependent Updating of Retrieved Fear Memories. Neuropsychopharmacology 2015; 40:3044-52. [PMID: 26062788 PMCID: PMC4864640 DOI: 10.1038/npp.2015.161] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 05/12/2015] [Accepted: 06/04/2015] [Indexed: 12/15/2022]
Abstract
Stored memories enter a temporary state of vulnerability following retrieval known as 'reconsolidation', a process that can allow memories to be modified to incorporate new information. Although reconsolidation has become an attractive target for treatment of memories related to traumatic past experiences, we still do not know what new information triggers the updating of retrieved memories. Here, we used biochemical markers of synaptic plasticity in combination with a novel behavioral procedure to determine what was learned during memory reconsolidation under normal retrieval conditions. We eliminated new information during retrieval by manipulating animals' training experience and measured changes in proteasome activity and GluR2 expression in the amygdala, two established markers of fear memory lability and reconsolidation. We found that eliminating new contextual information during the retrieval of memories for predictable and unpredictable fear associations prevented changes in proteasome activity and glutamate receptor expression in the amygdala, indicating that this new information drives the reconsolidation of both predictable and unpredictable fear associations on retrieval. Consistent with this, eliminating new contextual information prior to retrieval prevented the memory-impairing effects of protein synthesis inhibitors following retrieval. These results indicate that under normal conditions, reconsolidation updates memories by incorporating new contextual information into the memory trace. Collectively, these results suggest that controlling contextual information present during retrieval may be a useful strategy for improving reconsolidation-based treatments of traumatic memories associated with anxiety disorders such as post-traumatic stress disorder.
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Affiliation(s)
- Timothy J Jarome
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Nicole C Ferrara
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Janine L Kwapis
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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46
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Furini CRG, Myskiw JDC, Schmidt BE, Zinn CG, Peixoto PB, Pereira LD, Izquierdo I. The relationship between protein synthesis and protein degradation in object recognition memory. Behav Brain Res 2015. [PMID: 26200717 DOI: 10.1016/j.bbr.2015.07.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
For decades there has been a consensus that de novo protein synthesis is necessary for long-term memory. A second round of protein synthesis has been described for both extinction and reconsolidation following an unreinforced test session. Recently, it was shown that consolidation and reconsolidation depend not only on protein synthesis but also on protein degradation by the ubiquitin-proteasome system (UPS), a major mechanism responsible for protein turnover. However, the involvement of UPS on consolidation and reconsolidation of object recognition memory remains unknown. Here we investigate in the CA1 region of the dorsal hippocampus the involvement of UPS-mediated protein degradation in consolidation and reconsolidation of object recognition memory. Animals with infusion cannulae stereotaxically implanted in the CA1 region of the dorsal hippocampus, were exposed to an object recognition task. The UPS inhibitor β-Lactacystin did not affect the consolidation and the reconsolidation of object recognition memory at doses known to affect other forms of memory (inhibitory avoidance, spatial learning in a water maze) while the protein synthesis inhibitor anisomycin impaired the consolidation and the reconsolidation of the object recognition memory. However, β-Lactacystin was able to reverse the impairment caused by anisomycin on the reconsolidation process in the CA1 region of the hippocampus. Therefore, it is possible to postulate a direct link between protein degradation and protein synthesis during the reconsolidation of the object recognition memory.
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Affiliation(s)
- Cristiane R G Furini
- National Institute of Translational Neuroscience (INNT), National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd Floor, 90610-000 Porto Alegre, RS, Brazil
| | - Jociane de C Myskiw
- National Institute of Translational Neuroscience (INNT), National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd Floor, 90610-000 Porto Alegre, RS, Brazil
| | - Bianca E Schmidt
- National Institute of Translational Neuroscience (INNT), National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd Floor, 90610-000 Porto Alegre, RS, Brazil
| | - Carolina G Zinn
- National Institute of Translational Neuroscience (INNT), National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd Floor, 90610-000 Porto Alegre, RS, Brazil
| | - Patricia B Peixoto
- National Institute of Translational Neuroscience (INNT), National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd Floor, 90610-000 Porto Alegre, RS, Brazil
| | - Luiza D Pereira
- National Institute of Translational Neuroscience (INNT), National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd Floor, 90610-000 Porto Alegre, RS, Brazil
| | - Ivan Izquierdo
- National Institute of Translational Neuroscience (INNT), National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd Floor, 90610-000 Porto Alegre, RS, Brazil.
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47
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Jarome TJ, Lubin FD. Epigenetic mechanisms of memory formation and reconsolidation. Neurobiol Learn Mem 2014; 115:116-27. [PMID: 25130533 PMCID: PMC4250295 DOI: 10.1016/j.nlm.2014.08.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 08/02/2014] [Accepted: 08/05/2014] [Indexed: 10/24/2022]
Abstract
Memory consolidation involves transcriptional control of genes in neurons to stabilize a newly formed memory. Following retrieval, a once consolidated memory destabilizes and again requires gene transcription changes in order to restabilize, a process referred to as reconsolidation. Understanding the molecular mechanisms of gene transcription during the consolidation and reconsolidation processes could provide crucial insights into normal memory formation and memory dysfunction associated with psychiatric disorders. In the past decade, modifications of epigenetic markers such as DNA methylation and posttranslational modifications of histone proteins have emerged as critical transcriptional regulators of gene expression during initial memory formation and after retrieval. In light of the rapidly growing literature in this exciting area of research, we here examine the most recent and latest evidence demonstrating how memory acquisition and retrieval trigger epigenetic changes during the consolidation and reconsolidation phases to impact behavior. In particular we focus on the reconsolidation process, where we discuss the already identified epigenetic regulators of gene transcription during memory reconsolidation, while exploring other potential epigenetic modifications that may also be involved, and expand on how these epigenetic modifications may be precisely and temporally controlled by important signaling cascades critical to the reconsolidation process. Finally, we explore the possibility that epigenetic mechanisms may serve to regulate a system or circuit level reconsolidation process and may be involved in retrieval-dependent memory updating. Hence, we propose that epigenetic mechanisms coordinate changes in neuronal gene transcription, not only during the initial memory consolidation phase, but are triggered by retrieval to regulate molecular and cellular processes during memory reconsolidation.
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Affiliation(s)
- Timothy J Jarome
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Farah D Lubin
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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48
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Eisenhardt D. Molecular mechanisms underlying formation of long-term reward memories and extinction memories in the honeybee (Apis mellifera). ACTA ACUST UNITED AC 2014; 21:534-42. [PMID: 25225299 PMCID: PMC4175491 DOI: 10.1101/lm.033118.113] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The honeybee (Apis mellifera) has long served as an invertebrate model organism for reward learning and memory research. Its capacity for learning and memory formation is rooted in the ecological need to efficiently collect nectar and pollen during summer to ensure survival of the hive during winter. Foraging bees learn to associate a flower's characteristic features with a reward in a way that resembles olfactory appetitive classical conditioning, a learning paradigm that is used to study mechanisms underlying learning and memory formation in the honeybee. Due to a plethora of studies on appetitive classical conditioning and phenomena related to it, the honeybee is one of the best characterized invertebrate model organisms from a learning psychological point of view. Moreover, classical conditioning and associated behavioral phenomena are surprisingly similar in honeybees and vertebrates, suggesting a convergence of underlying neuronal processes, including the molecular mechanisms that contribute to them. Here I review current thinking on the molecular mechanisms underlying long-term memory (LTM) formation in honeybees following classical conditioning and extinction, demonstrating that an in-depth analysis of the molecular mechanisms of classical conditioning in honeybees might add to our understanding of associative learning in honeybees and vertebrates.
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Affiliation(s)
- Dorothea Eisenhardt
- Department of Biology, Chemistry, Pharmacy, Institute of Biology, Neurobiology, Freie Universität Berlin, 14195 Berlin, Germany
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49
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Phosphorylation regulates mycobacterial proteasome. J Microbiol 2014; 52:743-54. [PMID: 25224505 DOI: 10.1007/s12275-014-4416-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 07/22/2014] [Accepted: 07/23/2014] [Indexed: 12/31/2022]
Abstract
Mycobacterium tuberculosis possesses a proteasome system that is required for the microbe to resist elimination by the host immune system. Despite the importance of the proteasome in the pathogenesis of tuberculosis, the molecular mechanisms by which proteasome activity is controlled remain largely unknown. Here, we demonstrate that the α-subunit (PrcA) of the M. tuberculosis proteasome is phosphorylated by the PknB kinase at three threonine residues (T84, T202, and T178) in a sequential manner. Furthermore, the proteasome with phosphorylated PrcA enhances the degradation of Ino1, a known proteasomal substrate, suggesting that PknB regulates the proteolytic activity of the proteasome. Previous studies showed that depletion of the proteasome and the proteasome-associated proteins decreases resistance to reactive nitrogen intermediates (RNIs) but increases resistance to hydrogen peroxide (H2O2). Here we show that PknA phosphorylation of unprocessed proteasome β-subunit (pre-PrcB) and α-subunit reduces the assembly of the proteasome complex and thereby enhances the mycobacterial resistance to H2O2 and that H2O2 stress diminishes the formation of the proteasome complex in a PknA-dependent manner. These findings indicate that phosphorylation of the M. tuberculosis proteasome not only modulates proteolytic activity of the proteasome, but also affects the proteasome complex formation contributing to the survival of M. tuberculosis under oxidative stress conditions.
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50
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Jarome TJ, Helmstetter FJ. Protein degradation and protein synthesis in long-term memory formation. Front Mol Neurosci 2014; 7:61. [PMID: 25018696 PMCID: PMC4072070 DOI: 10.3389/fnmol.2014.00061] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 06/09/2014] [Indexed: 11/19/2022] Open
Abstract
Long-term memory (LTM) formation requires transient changes in the activity of intracellular signaling cascades that are thought to regulate new gene transcription and de novo protein synthesis in the brain. Consistent with this, protein synthesis inhibitors impair LTM for a variety of behavioral tasks when infused into the brain around the time of training or following memory retrieval, suggesting that protein synthesis is a critical step in LTM storage in the brain. However, evidence suggests that protein degradation mediated by the ubiquitin-proteasome system (UPS) may also be a critical regulator of LTM formation and stability following retrieval. This requirement for increased protein degradation has been shown in the same brain regions in which protein synthesis is required for LTM storage. Additionally, increases in the phosphorylation of proteins involved in translational control parallel increases in protein polyubiquitination and the increased demand for protein degradation is regulated by intracellular signaling molecules thought to regulate protein synthesis during LTM formation. In some cases inhibiting proteasome activity can rescue memory impairments that result from pharmacological blockade of protein synthesis, suggesting that protein degradation may control the requirement for protein synthesis during the memory storage process. Results such as these suggest that protein degradation and synthesis are both critical for LTM formation and may interact to properly “consolidate” and store memories in the brain. Here, we review the evidence implicating protein synthesis and degradation in LTM storage and highlight the areas of overlap between these two opposing processes. We also discuss evidence suggesting these two processes may interact to properly form and store memories. LTM storage likely requires a coordinated regulation between protein degradation and synthesis at multiple sites in the mammalian brain.
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Affiliation(s)
- Timothy J Jarome
- Department of Neurobiology, University of Alabama at Birmingham Birmingham, AL, USA ; Department of Psychology, University of Wisconsin-Milwaukee Milwaukee, WI, USA
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee Milwaukee, WI, USA
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