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Farrell K, Auerbach A, Liu C, Martin K, Pareno M, Ray WK, Helm RF, Biase F, Jarome TJ. Sex-differences in proteasome-dependent K48-polyubiquitin signaling in the amygdala are developmentally regulated in rats. Biol Sex Differ 2023; 14:80. [PMID: 37950270 PMCID: PMC10638793 DOI: 10.1186/s13293-023-00566-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND Sex differences have been observed in several brain regions for the molecular mechanisms involved in baseline (resting) and memory-related processes. The ubiquitin proteasome system (UPS) is a major protein degradation pathway in cells. Sex differences have been observed in lysine-48 (K48)-polyubiquitination, the canonical degradation mark of the UPS, both at baseline and during fear memory formation within the amygdala. Here, we investigated when, how, and why these baseline sex differences arise and whether both sexes require the K48-polyubiquitin mark for memory formation in the amygdala. METHODS We used a combination of molecular, biochemical and proteomic approaches to examine global and protein-specific K48-polyubiquitination and DNA methylation levels at a major ubiquitin coding gene (Uba52) at baseline in the amygdala of male and female rats before and after puberty to determine if sex differences were developmentally regulated. We then used behavioral and genetic approaches to test the necessity of K48-polyubiquitination in the amygdala for fear memory formation. RESULTS We observed developmentally regulated baseline differences in Uba52 methylation and total K48-polyubiquitination, with sexual maturity altering levels specifically in female rats. K48-polyubiquitination at specific proteins changed across development in both male and female rats, but sex differences were present regardless of age. Lastly, we found that genetic inhibition of K48-polyubiquitination in the amygdala of female, but not male, rats impaired fear memory formation. CONCLUSIONS These results suggest that K48-polyubiquitination differentially targets proteins in the amygdala in a sex-specific manner regardless of age. However, sexual maturity is important in the developmental regulation of K48-polyubiquitination levels in female rats. Consistent with these data, K48-polyubiquitin signaling in the amygdala is selectively required to form fear memories in female rats. Together, these data indicate that sex-differences in baseline K48-polyubiquitination within the amygdala are developmentally regulated, which could have important implications for better understanding sex-differences in molecular mechanisms involved in processes relevant to anxiety-related disorders such as post-traumatic stress disorder (PTSD).
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Affiliation(s)
- Kayla Farrell
- School of Animal Sciences, Virginia Polytechnic Institute and State University, 175 West Campus Dr., 2150 Litton-Reaves Hall, Blacksburg, VA, 24061, USA
| | - Aubrey Auerbach
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Catherine Liu
- School of Animal Sciences, Virginia Polytechnic Institute and State University, 175 West Campus Dr., 2150 Litton-Reaves Hall, Blacksburg, VA, 24061, USA
| | - Kiley Martin
- School of Neuroscience, Virginia Polytechnic Institute and State University, 175 West Campus Dr., 2150 Litton-Reaves Hall, Blacksburg, VA, 24061, USA
| | - Myasia Pareno
- School of Animal Sciences, Virginia Polytechnic Institute and State University, 175 West Campus Dr., 2150 Litton-Reaves Hall, Blacksburg, VA, 24061, 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
| | - Fernando Biase
- School of Animal Sciences, Virginia Polytechnic Institute and State University, 175 West Campus Dr., 2150 Litton-Reaves Hall, Blacksburg, VA, 24061, USA
| | - Timothy J Jarome
- School of Animal Sciences, Virginia Polytechnic Institute and State University, 175 West Campus Dr., 2150 Litton-Reaves Hall, Blacksburg, VA, 24061, USA.
- School of Neuroscience, Virginia Polytechnic Institute and State University, 175 West Campus Dr., 2150 Litton-Reaves Hall, Blacksburg, VA, 24061, USA.
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2
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Patrick MB, Omar N, Werner CT, Mitra S, Jarome TJ. The ubiquitin-proteasome system and learning-dependent synaptic plasticity - A 10 year update. Neurosci Biobehav Rev 2023; 152:105280. [PMID: 37315660 PMCID: PMC11323321 DOI: 10.1016/j.neubiorev.2023.105280] [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] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 05/22/2023] [Accepted: 06/08/2023] [Indexed: 06/16/2023]
Abstract
Over 25 years ago, a seminal paper demonstrated that the ubiquitin-proteasome system (UPS) was involved in activity-dependent synaptic plasticity. Interest in this topic began to expand around 2008 following another seminal paper showing that UPS-mediated protein degradation controlled the "destabilization" of memories following retrieval, though we remained with only a basic understanding of how the UPS regulated activity- and learning-dependent synaptic plasticity. However, over the last 10 years there has been an explosion of papers on this topic that has significantly changed our understanding of how ubiquitin-proteasome signaling regulates synaptic plasticity and memory formation. Importantly, we now know that the UPS controls much more than protein degradation, is involved in plasticity underlying drugs of abuse and that there are significant sex differences in how ubiquitin-proteasome signaling is used for memory storage processes. Here, we aim to provide a critical 10-year update on the role of ubiquitin-proteasome signaling in synaptic plasticity and memory formation, including updated cellular models of how ubiquitin-proteasome activity could be regulating learning-dependent synaptic plasticity in the brain.
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Affiliation(s)
- Morgan B Patrick
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Nour Omar
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Craig T Werner
- Department of Pharmacology and Physiology, Oklahoma State University Center for Health Sciences, Tulsa, OK, USA; National Center for Wellness and Recovery, Oklahoma State University Center for Health Sciences, Tulsa, OK, USA.
| | - Swarup Mitra
- Department of Biomedical Sciences, Joan C Edwards School of Medicine, Marshall University, Huntington, WV, USA.
| | - Timothy J Jarome
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA; School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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3
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Fleischer AW, Frick KM. New perspectives on sex differences in learning and memory. Trends Endocrinol Metab 2023; 34:526-538. [PMID: 37500421 PMCID: PMC10617789 DOI: 10.1016/j.tem.2023.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/12/2023] [Accepted: 06/14/2023] [Indexed: 07/29/2023]
Abstract
Females have historically been disregarded in memory research, including the thousands of studies examining roles for the hippocampus, medial prefrontal cortex, and amygdala in learning and memory. Even when included, females are often judged based on male-centric behavioral and neurobiological standards, generating and perpetuating scientific stereotypes that females exhibit worse memories compared with males in domains such as spatial navigation and fear. Recent research challenges these dogmas by identifying sex-specific strategies in common memory tasks. Here, we discuss rodent data illustrating sex differences in spatial and fear memory, as well as the neural mechanisms underlying memory formation. The influence of sex steroid hormones in both sexes is discussed, as is the importance to basic and translational neuroscience of studying sex differences.
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Affiliation(s)
- Aaron W Fleischer
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Karyn M Frick
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
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4
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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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5
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Cozachenco D, Ribeiro FC, Ferreira ST. Defective proteostasis in Alzheimer's disease. Ageing Res Rev 2023; 85:101862. [PMID: 36693451 DOI: 10.1016/j.arr.2023.101862] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 01/11/2023] [Accepted: 01/20/2023] [Indexed: 01/22/2023]
Abstract
The homeostasis of cellular proteins, or proteostasis, is critical for neuronal function and for brain processes, including learning and memory. Increasing evidence indicates that defective proteostasis contributes to the progression of neurodegenerative disorders, including Alzheimer's disease (AD), the most prevalent form of dementia in the elderly. Proteostasis comprises a set of cellular mechanisms that control protein synthesis, folding, post-translational modification and degradation, all of which are deregulated in AD. Importantly, deregulation of proteostasis plays a key role in synapse dysfunction and in memory impairment, the major clinical manifestation of AD. Here, we discuss molecular pathways involved in protein synthesis and degradation that are altered in AD, and possible pharmacological approaches to correct these defects.
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Affiliation(s)
- Danielle Cozachenco
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
| | - Felipe C Ribeiro
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
| | - Sergio T Ferreira
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
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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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Gustin A, Navabpour S, Farrell K, Martin K, DuVall J, Keith Ray W, Helm RF, Jarome TJ. Protein SUMOylation is a sex-specific regulator of fear memory formation in the amygdala. Behav Brain Res 2022; 430:113928. [PMID: 35597476 PMCID: PMC10431910 DOI: 10.1016/j.bbr.2022.113928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/11/2022] [Accepted: 05/12/2022] [Indexed: 11/25/2022]
Abstract
Strong evidence has implicated ubiquitin signaling in the process of fear memory formation. While less abundant than ubiquitination, evidence suggests that protein SUMOylation may also be involved in fear memory formation in neurons. However, the importance of amygdala protein SUMOylation in fear memory formation has never been directly examined. Furthermore, while recent evidence indicates that males and females differ significantly in the requirement for ubiquitin signaling during fear memory formation, whether sex differences also exist in the importance of protein SUMOylation to this process remains unknown. Here we found that males and females differ in the requirement for protein SUMOylation in the amygdala during fear memory formation. Western blot analysis revealed that while females had higher resting levels of SUMOylation, both sexes showed global increases following fear conditioning. However, SUMOylation-specific proteomic analysis revealed that only females have increased targeting of individual proteins by SUMOylation following fear conditioning, some of which were heat shock proteins. This suggests that protein SUMOylation is more robustly engaged in the amygdala of females following fear conditioning. In vivo siRNA mediated knockdown of Ube2i, the coding gene for the essential E2 ligase for SUMOylation conjugation, in the amygdala impaired fear memory in males without any effect in females. Importantly, higher siRNA concentrations than what was needed to impair memory in males reduced Ube2i levels in the amygdala of females but resulted in an increase in SUMOylation levels, suggesting a compensatory effect in females that was not observed in males. Collectively, these data reveal a novel, sex-specific role for protein SUMOylation in the amygdala during fear memory formation and expand our understanding of how ubiquitin-like signaling regulates memory formation.
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Affiliation(s)
- Aspen Gustin
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Shaghayegh Navabpour
- Fralin Biomedical Research Institute, Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | - Kayla Farrell
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Kiley Martin
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Jessica DuVall
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, 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
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA; Fralin Biomedical Research Institute, Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA; School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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8
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Sun Y, Zhao J, Song X, Sun Z, Zhang R, Zhong J, Huang X, Dong Y, Yu Q, Dong F, Li Z, Fan L, Wang M, Peng C, Wang F. Effects of marginal zinc deficiency on learning and memory ability after birth. Food Funct 2022; 13:7204-7214. [PMID: 35713090 DOI: 10.1039/d2fo01074g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Zinc deficiency during pregnancy and severe zinc deficiency after birth both impaired learning and memory ability, but the effects of marginal zinc deficiency (MZD) after birth on learning and memory are unclear. In the first experiment, 4-week-old male rats were randomly divided into three groups: the marginal zinc-deficient group (MZG, 10 mg kg-1, 1/3 RNI), normal zinc group (NZG, 30 mg kg-1, RNI), and paired zinc group (PZG, 30 mg kg-1). After a 4-week feeding period, the brain weight, brain coefficient, and serum zinc concentration were measured, and hippocampal proteomics analysis was performed. In the second experiment, 4-week-old male rats were fed the same diet for 8 weeks. In addition to the previously mentioned indicators, the Morris water maze results, brain pathology, post-translational modifications (PTMs) of hippocampal proteins, and the concentrations of indicators known to be related to learning and memory were analyzed. In both experiments, compared with those of the NZG, the food intake, body weight and serum zinc of the MZG were significantly decreased, and the brain weight was unchanged, but the brain coefficient was increased. Two hippocampal proteomics analyses and PTM screening showed that MZD did not change the expression and PTM of proteins. The brain pathology, learning, memory and the concentrations of indicators known to be related to learning and memory were not changed by MZD. Our study confirmed that marginal zinc deficiency (10 mg kg-1, 1/3 RNI) had no effect on the learning and memory abilities of rats after birth.
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Affiliation(s)
- Yongzhi Sun
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Jiali Zhao
- Yiwu Maternity and Children Hospital, Yiwu, Zhejiang, China
| | - Xinyu Song
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Zhaohui Sun
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Rui Zhang
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Jiayi Zhong
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Xiaocai Huang
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Yingran Dong
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Qingli Yu
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Feng Dong
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Zixiang Li
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Lina Fan
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Maoqing Wang
- National Key Disciplines of Nutrition and Food Hygiene, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin 150081, China.
| | - Chenghai Peng
- Department of Cardiology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, 150081, China.
| | - Fan Wang
- Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, China.
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9
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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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