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Miranda P, Mirisis AA, Kukushkin NV, Carew TJ. Pattern detection in the TGFβ cascade controls the induction of long-term synaptic plasticity. Proc Natl Acad Sci U S A 2023; 120:e2300595120. [PMID: 37748056 PMCID: PMC10556637 DOI: 10.1073/pnas.2300595120] [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: 01/13/2023] [Accepted: 08/11/2023] [Indexed: 09/27/2023] Open
Abstract
Transforming growth factor β (TGFβ) is required for long-term memory (LTM) for sensitization in Aplysia. When LTM is induced using a two-trial training protocol, TGFβ inhibition only blocks LTM when administrated at the second, not the first trial. Here, we show that TGFβ acts as a "repetition detector" during the induction of two-trial LTM. Secretion of the biologically inert TGFβ proligand must coincide with its proteolytic activation by the Bone morphogenetic protein-1 (BMP-1/Tolloid) metalloprotease, which occurs specifically during trial two of our two-trial training paradigm. This paradigm establishes long-term synaptic facilitation (LTF), the cellular correlate of LTM. BMP-1 application paired with a single serotonin (5HT) pulse induced LTF, whereas neither a single 5HT pulse nor BMP-1 alone effectively did so. On the other hand, inhibition of endogenous BMP-1 activity blocked the induction of two-trial LTF. These results suggest a unique role for TGFβ in the interaction of repeated trials: during learning, repeated stimuli engage separate steps of the TGFβ cascade that together are necessary for the induction of long-lasting memories.
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Affiliation(s)
- Paige Miranda
- Center for Neural Science, New York University, New York, NY10003
| | | | - Nikolay V. Kukushkin
- Center for Neural Science, New York University, New York, NY10003
- Liberal Studies, New York University, New York, NY10003
| | - Thomas J. Carew
- Center for Neural Science, New York University, New York, NY10003
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2
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Zha C, Sossin WS. The molecular diversity of plasticity mechanisms underlying memory: An evolutionary perspective. J Neurochem 2022; 163:444-460. [PMID: 36326567 DOI: 10.1111/jnc.15717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/29/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022]
Abstract
Experience triggers molecular cascades in organisms (learning) that lead to alterations (memory) to allow the organism to change its behavior based on experience. Understanding the molecular mechanisms underlying memory, particularly in the nervous system of animals, has been an exciting scientific challenge for neuroscience. We review what is known about forms of neuronal plasticity that underlie memory highlighting important issues in the field: (1) the importance of being able to measure how neurons are activated during learning to identify the form of plasticity that underlies memory, (2) the many distinct forms of plasticity important for memories that naturally decay both within and between organisms, and (3) unifying principles underlying the formation and maintenance of long-term memories. Overall, the diversity of molecular mechanisms underlying memories that naturally decay contrasts with more unified molecular mechanisms implicated in long-lasting changes. Despite many advances, important questions remain as to which mechanisms of neuronal plasticity underlie memory.
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Affiliation(s)
- Congyao Zha
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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3
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The evolution of synaptic and cognitive capacity: Insights from the nervous system transcriptome of Aplysia. Proc Natl Acad Sci U S A 2022; 119:e2122301119. [PMID: 35867761 PMCID: PMC9282427 DOI: 10.1073/pnas.2122301119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The gastropod mollusk Aplysia is an important model for cellular and molecular neurobiological studies, particularly for investigations of molecular mechanisms of learning and memory. We developed an optimized assembly pipeline to generate an improved Aplysia nervous system transcriptome. This improved transcriptome enabled us to explore the evolution of cognitive capacity at the molecular level. Were there evolutionary expansions of neuronal genes between this relatively simple gastropod Aplysia (20,000 neurons) and Octopus (500 million neurons), the invertebrate with the most elaborate neuronal circuitry and greatest behavioral complexity? Are the tremendous advances in cognitive power in vertebrates explained by expansion of the synaptic proteome that resulted from multiple rounds of whole genome duplication in this clade? Overall, the complement of genes linked to neuronal function is similar between Octopus and Aplysia. As expected, a number of synaptic scaffold proteins have more isoforms in humans than in Aplysia or Octopus. However, several scaffold families present in mollusks and other protostomes are absent in vertebrates, including the Fifes, Lev10s, SOLs, and a NETO family. Thus, whereas vertebrates have more scaffold isoforms from select families, invertebrates have additional scaffold protein families not found in vertebrates. This analysis provides insights into the evolution of the synaptic proteome. Both synaptic proteins and synaptic plasticity evolved gradually, yet the last deuterostome-protostome common ancestor already possessed an elaborate suite of genes associated with synaptic function, and critical for synaptic plasticity.
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Jin I, Kassabov S, Kandel ER, Hawkins RD. Possible novel features of synaptic regulation during long-term facilitation in Aplysia. ACTA ACUST UNITED AC 2021; 28:218-227. [PMID: 34131053 PMCID: PMC8212780 DOI: 10.1101/lm.053124.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 04/23/2021] [Indexed: 11/24/2022]
Abstract
Most studies of molecular mechanisms of synaptic plasticity have focused on the sequence of changes either at individual synapses or in the cell nucleus. However, studies of long-term facilitation at Aplysia sensory neuron–motor neuron synapses in isolated cell culture suggest two additional features of facilitation. First, that there is also regulation of the number of synaptic contacts between two neurons, which may occur at the level of cell pair-specific branch points in the neuronal arbor. Branch points contain many molecules that are involved in protein synthesis-dependent long-term facilitation including neurotrophins and the RNA binding protein CPEB. Second, the regulation involves homeostatic feedback and tends to keep the total number of contacts between two neurons at a fairly constant level both at rest and following facilitation. That raises the question of how facilitation and homeostasis can coexist. A possible answer is suggested by the findings that they both involve spontaneous transmission and postsynaptic Ca2+, which can have bidirectional effects similar to LTP and LTD in hippocampus. In addition, long-term facilitation can involve a change in the set point of homeostasis, which could be encoded by plasticity molecules such as CPEB and/or PKM. A computational model based on these ideas can qualitatively simulate the basic features of both facilitation and homeostasis of the number of contacts.
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Affiliation(s)
- Iksung Jin
- Department of Neuroscience, Columbia University, New York, New York 10032, USA
| | - Stefan Kassabov
- Department of Neuroscience, Columbia University, New York, New York 10032, USA
| | - Eric R Kandel
- Department of Neuroscience, Columbia University, New York, New York 10032, USA.,New York State Psychiatric Institute, New York, New York 10032, USA.,Howard Hughes Medical Institute, New York, New York 10032, USA
| | - Robert D Hawkins
- Department of Neuroscience, Columbia University, New York, New York 10032, USA.,New York State Psychiatric Institute, New York, New York 10032, USA
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5
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Gold AR, Glanzman DL. The central importance of nuclear mechanisms in the storage of memory. Biochem Biophys Res Commun 2021; 564:103-113. [PMID: 34020774 DOI: 10.1016/j.bbrc.2021.04.125] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 12/14/2022]
Abstract
The neurobiological nature of the memory trace (engram) remains controversial. The most widely accepted hypothesis at present is that long-term memory is stored as stable, learning-induced changes in synaptic connections. This hypothesis, the synaptic plasticity hypothesis of memory, is supported by extensive experimental data gathered from over 50 years of research. Nonetheless, there are important mnemonic phenomena that the synaptic plasticity hypothesis cannot, or cannot readily, account for. Furthermore, recent work indicates that epigenetic and genomic mechanisms play heretofore underappreciated roles in memory. Here, we critically assess the evidence that supports the synaptic plasticity hypothesis and discuss alternative non-synaptic, nuclear mechanisms of memory storage, including DNA methylation and retrotransposition. We argue that long-term encoding of memory is mediated by nuclear processes; synaptic plasticity, by contrast, represents a means of relatively temporary memory storage. In addition, we propose that memories are evaluated for their mnemonic significance during an initial period of synaptic storage; if assessed as sufficiently important, the memories then undergo nuclear encoding.
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Affiliation(s)
- Adam R Gold
- Behavioral Neuroscience Program, Department of Psychology, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
| | - David L Glanzman
- Department of Integrative Biology & Physiology, UCLA College, University of California, Los Angeles, Los Angeles, CA, 90095, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA, 90095, USA; Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
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6
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Nikitin VP, Solntseva SV, Kozyrev SA. Changes in Amnesia Parameters over Time after Long-Term Memory Disruption with Protein Kinase Mζ Inhibitor. Bull Exp Biol Med 2019; 167:711-715. [PMID: 31655990 DOI: 10.1007/s10517-019-04605-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Indexed: 11/29/2022]
Abstract
We studied the involvement of protein kinase Mζ (PKMζ) in the mechanisms of amnesia development within 10 days after disruption of conditioned food aversion memory with ZIP (a PKMζ inhibitor). Repeated training performed in 3 days after amnesia induction with ZIP, led to the formation of conditioned food aversion memory, but the number of combined presentations of food and reinforcer stimuli was lower than during the initial training. Repeated training performed in 10 days after amnesia induction also led to memory formation, but the number of combined presentations of the stimuli was similar to that during the initial training. It was hypothesized that at the early stages of ZIP-induced amnesia, residual memory trace can be restored and amplified during repeated training, which led to memory expression at the behavioral level. At the late stages of amnesia, this memory trace was completely erased and repeated training led to the formation of a new memory. Thus, PKMζ inhibition results in the relatively fast impairment of memory retrieval and induces long-term process of memory erasing.
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Affiliation(s)
- V P Nikitin
- P. K. Anokhin Research Institute of Normal Physiology, Moscow, Russia.
| | - S V Solntseva
- P. K. Anokhin Research Institute of Normal Physiology, Moscow, Russia
| | - S A Kozyrev
- P. K. Anokhin Research Institute of Normal Physiology, Moscow, Russia
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7
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aPKC in neuronal differentiation, maturation and function. Neuronal Signal 2019; 3:NS20190019. [PMID: 32269838 PMCID: PMC7104321 DOI: 10.1042/ns20190019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 12/17/2022] Open
Abstract
The atypical Protein Kinase Cs (aPKCs)—PRKCI, PRKCZ and PKMζ—form a subfamily within the Protein Kinase C (PKC) family. These kinases are expressed in the nervous system, including during its development and in adulthood. One of the aPKCs, PKMζ, appears to be restricted to the nervous system. aPKCs are known to play a role in a variety of cellular responses such as proliferation, differentiation, polarity, migration, survival and key metabolic functions such as glucose uptake, that are critical for nervous system development and function. Therefore, these kinases have garnered a lot of interest in terms of their functional role in the nervous system. Here we review the expression and function of aPKCs in neural development and in neuronal maturation and function. Despite seemingly paradoxical findings with genetic deletion versus gene silencing approaches, we posit that aPKCs are likely candidates for regulating many important neurodevelopmental and neuronal functions, and may be associated with a number of human neuropsychiatric diseases.
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8
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Isoform Specificity of PKMs during Long-Term Facilitation in Aplysia Is Mediated through Stabilization by KIBRA. J Neurosci 2019; 39:8632-8644. [PMID: 31537706 DOI: 10.1523/jneurosci.0943-19.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/29/2019] [Accepted: 08/03/2019] [Indexed: 01/18/2023] Open
Abstract
Persistent activity of protein kinase M (PKM), the truncated form of protein kinase C (PKC), can maintain long-term changes in synaptic strength in many systems, including the hermaphrodite marine mollusk, Aplysia californica Moreover, different types of long-term facilitation (LTF) in cultured Aplysia sensorimotor synapses rely on the activities of different PKM isoforms in the presynaptic sensory neuron and postsynaptic motor neuron. When the atypical PKM isoform is required, the kidney and brain expressed adaptor protein (KIBRA) is also required. Here, we explore how this isoform specificity is established. We find that PKM overexpression in the motor neuron, but not the sensory neuron, is sufficient to increase synaptic strength and that this activity is not isoform-specific. KIBRA is not the rate-limiting step in facilitation since overexpression of KIBRA is neither sufficient to increase synaptic strength, nor to prolong a form of PKM-dependent intermediate synaptic facilitation. However, the isoform specificity of dominant-negative-PKMs to erase LTF is correlated with isoform-specific competition for stabilization by KIBRA. We identify a new conserved region of KIBRA. Different splice isoforms in this region stabilize different PKMs based on the isoform-specific sequence of an α-helix "handle" in the PKMs. Thus, specific stabilization of distinct PKMs by different isoforms of KIBRA can explain the isoform specificity of PKMs during LTF in Aplysia SIGNIFICANCE STATEMENT Long-lasting changes in synaptic plasticity associated with memory formation are maintained by persistent protein kinases. We have previously shown in the Aplysia sensorimotor model that distinct isoforms of persistently active protein kinase Cs (PKMs) maintain distinct forms of long-lasting synaptic changes, even when both forms are expressed in the same motor neuron. Here, we show that, while the effects of overexpression of PKMs are not isoform-specific, isoform specificity is defined by a "handle" helix in PKMs that confers stabilization by distinct splice forms in a previously undefined domain of the adaptor protein KIBRA. Thus, we define new regions in both KIBRA and PKMs that define the isoform specificity for maintaining synaptic strength in distinct facilitation paradigms.
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9
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Farah CA, Dunn TW, Hastings MH, Ferguson L, Gao C, Gong K, Sossin WS. A role for Numb in Protein kinase M (PKM)-mediated increase in surface AMPA receptors during facilitation in Aplysia. J Neurochem 2019; 150:366-384. [PMID: 31254393 DOI: 10.1111/jnc.14807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 06/25/2019] [Accepted: 06/26/2019] [Indexed: 12/15/2022]
Abstract
There is considerable evidence from both vertebrates and invertebrates that persistently active protein kinases maintain changes in synaptic strength that underlie memory. In the hermaphrodite marine mollusk, Aplysia californica, truncated forms of protein kinase C (PKC) termed protein kinase Ms have been implicated in both intermediate- and long-term facilitation, an increase in synaptic strength between sensory neurons and motor neurons thought to underlie behavioural sensitization in the animal. However, few substrates have been identified as candidates that could mediate this increase in synaptic strength. PKMs have been proposed to maintain synaptic strength through preventing endocytosis of AMPA receptors. Numb is a conserved regulator of endocytosis that is modulated by phosphorylation. We have identified and cloned Aplysia Numb (ApNumb). ApNumb contains three conserved PKC phosphorylation sites and PKMs generated from classical and atypical Aplysia PKCs can phosphorylate ApNumb in vitro and in cells. Over-expression of ApNumb that lacks the conserved PKC phosphorylation sites blocks increases in surface levels of a pHluorin-tagged Aplysia glutamate receptor measured using live imaging after intermediate- or long-term facilitation. Over-expression of this form of ApNumb did not block increases in synaptic strength seen during intermediate-term facilitation, but did block increases in synaptic strength seen during long-term facilitation. There was no effect of over-expression of this form of ApNumb on other putative Numb targets as measured using increases in calcium downstream of neurotrophins or agonists of metabotropic glutamate receptors. These results suggest that in Aplysia neurons, Numb specifically regulates AMPA receptor trafficking and is an attractive candidate for a target of PKMs in long-term maintenance of synaptic strength. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/. Open Science: This manuscript was awarded with the Open Materials Badge For more information see: https://cos.io/our-services/open-science-badges/.
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Affiliation(s)
- Carole A Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Tyler W Dunn
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Margaret H Hastings
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Larissa Ferguson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Cherry Gao
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Katrina Gong
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
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10
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Experiments with Snails Add to Our Knowledge about the Role of aPKC Subfamily Kinases in Learning. Int J Mol Sci 2019; 20:ijms20092117. [PMID: 31035721 PMCID: PMC6539039 DOI: 10.3390/ijms20092117] [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: 03/26/2019] [Revised: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 12/28/2022] Open
Abstract
Protein kinase Mζ is considered important for memory formation and maintenance in different species, including invertebrates. PKMζ participates in multiple molecular pathways in neurons, regulating translation initiation rate, AMPA receptors turnover, synaptic scaffolding assembly, and other processes. Here, for the first time, we established the sequence of mRNA encoding PKMζ homolog in land snail Helix lucorum. We annotated important features of this mRNA: domains, putative capping sites, translation starts, and splicing sites. We discovered that this mRNA has at least two isoforms, and one of them lacks sequence encoding C1 domain. C1 deletion may be unique for snail because it has not been previously found in other species. We performed behavioral experiments with snails, measured expression levels of identified isoforms, and confirmed that their expression correlates with one type of learning.
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11
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Histone acetylation determines transcription of atypical protein kinases in rat neurons. Sci Rep 2019; 9:4332. [PMID: 30867503 PMCID: PMC6416243 DOI: 10.1038/s41598-019-40823-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 02/11/2019] [Indexed: 01/19/2023] Open
Abstract
It is widely accepted that memory consolidation requires de-novo transcription of memory-related genes. Epigenetic modifications, particularly histone acetylation, may facilitate gene transcription, but their potential molecular targets are poorly characterized. In the current study, we addressed the question of epigenetic control of atypical protein kinases (aPKC) that are critically involved in memory consolidation and maintenance. We examined the patterns of expression of two aPKC genes (Prkci and Prkcz) in rat cultured cortical neurons treated with histone deacetylase inhibitors. Histone hyperacetylation in the promoter region of Prkci gene elicited direct activation of transcriptional machinery, resulting in increased production of PKCλ mRNA. In parallel, histone hyperacetylation in the upstream promoter of Prkcz gene led to appearance of the corresponding PKCζ transcripts that are almost absent in the brain in resting conditions. In contrast, histone hyperacetylation in the downstream promoter of Prkcz gene was accompanied by a decreased expression of the brain-specific PKMζ products. We showed that epigenetically-triggered differential expression of PKMζ and PKCζ mRNA depended on protein synthesis. Summarizing, our results suggest that genes, encoding memory-related aPKC, may represent the molecular targets for epigenetic regulation through posttranslational histone modifications.
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12
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Hastings MH, Qiu A, Zha C, Farah CA, Mahdid Y, Ferguson L, Sossin WS. The zinc fingers of the small optic lobes calpain bind polyubiquitin. J Neurochem 2018; 146:429-445. [PMID: 29808476 DOI: 10.1111/jnc.14473] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/09/2018] [Accepted: 05/22/2018] [Indexed: 12/27/2022]
Abstract
The small optic lobes (SOL) calpain is a highly conserved member of the calpain family expressed in the nervous system. A dominant negative form of the SOL calpain inhibited consolidation of one form of synaptic plasticity, non-associative facilitation, in sensory-motor neuronal cultures in Aplysia, presumably by inhibiting cleavage of protein kinase Cs (PKCs) into constitutively active protein kinase Ms (PKMs) (Hu et al. 2017a). SOL calpains have a conserved set of 5-6 N-terminal zinc fingers. Bioinformatic analysis suggests that these zinc fingers could bind to ubiquitin. In this study, we show that both the Aplysia and mouse SOL calpain (also known as Calpain 15) zinc fingers bind ubiquitinated proteins, and we confirm that Aplysia SOL binds poly- but not mono- or diubiquitin. No specific zinc finger is required for polyubiquitin binding. Neither polyubiquitin nor calcium was sufficient to induce purified Aplysia SOL calpain to autolyse or to cleave the atypical PKC to PKM in vitro. In Aplysia, over-expression of the atypical PKC in sensory neurons leads to an activity-dependent cleavage event and an increase in nuclear ubiquitin staining. Activity-dependent cleavage is partially blocked by a dominant negative SOL calpain, but not by a dominant negative classical calpain. The cleaved PKM was stabilized by the dominant negative classical calpain and destabilized by a dominant negative form of the PKM stabilizing protein KIdney/BRAin protein. These studies provide new insight into SOL calpain's function and regulation. Open Data: Materials are available on https://cos.io/our-services/open-science-badges/ https://osf.io/93n6m/.
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Affiliation(s)
- Margaret H Hastings
- Department of Psychology, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Alvin Qiu
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Congyao Zha
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Carole A Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Yacine Mahdid
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Larissa Ferguson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Wayne S Sossin
- Department of Psychology, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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13
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Hapak SM, Ghosh S, Rothlin CV. Axon Regeneration: Antagonistic Signaling Pairs in Neuronal Polarization. Trends Mol Med 2018; 24:615-629. [PMID: 29934283 DOI: 10.1016/j.molmed.2018.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 05/07/2018] [Accepted: 05/09/2018] [Indexed: 01/29/2023]
Abstract
Genome-wide screens, proteomics, and candidate-based approaches have identified numerous genes associated with neuronal regeneration following central nervous system (CNS) injury. Despite significant progress, functional recovery remains a challenge, even in model systems. Neuronal function depends on segregation of axonal versus dendritic domains. A key to functional recovery may lie in recapitulating the developmental signals that instruct axon specification and growth in adult neurons post-injury. Theoretically, binary activator-inhibitor elements operating as a Turing-like system within neurons can specify axonal versus dendritic domains and promote axon growth. We review here various molecules implicated in axon specification that function as signaling pairs driving neuronal polarization and axon growth.
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Affiliation(s)
- Sophie M Hapak
- Department of Medicine, School of Medicine, University of Minnesota, 401 East River Parkway, Minneapolis, MN 55455, USA
| | - Sourav Ghosh
- Department of Neurology, School of Medicine, Yale University, 300 George Street, New Haven, CT 06511, USA; Department of Pharmacology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, USA; Equal contribution.
| | - Carla V Rothlin
- Department of Pharmacology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, USA; Department of Immunobiology, School of Medicine, Yale University, 300 Cedar Street, New Haven, CT 06520, USA; Equal contribution.
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14
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Sossin WS. Memory Synapses Are Defined by Distinct Molecular Complexes: A Proposal. Front Synaptic Neurosci 2018; 10:5. [PMID: 29695960 PMCID: PMC5904272 DOI: 10.3389/fnsyn.2018.00005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/26/2018] [Indexed: 12/17/2022] Open
Abstract
Synapses are diverse in form and function. While there are strong evidential and theoretical reasons for believing that memories are stored at synapses, the concept of a specialized “memory synapse” is rarely discussed. Here, we review the evidence that memories are stored at the synapse and consider the opposing possibilities. We argue that if memories are stored in an active fashion at synapses, then these memory synapses must have distinct molecular complexes that distinguish them from other synapses. In particular, examples from Aplysia sensory-motor neuron synapses and synapses on defined engram neurons in rodent models are discussed. Specific hypotheses for molecular complexes that define memory synapses are presented, including persistently active kinases, transmitter receptor complexes and trans-synaptic adhesion proteins.
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Affiliation(s)
- Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
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15
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Abstract
Elucidating the molecular mechanisms that maintain long-term memory is a fundamental goal of neuroscience. Accumulating evidence suggests that persistent signaling by the atypical protein kinase C (PKC) isoform protein kinase Mζ (PKMζ) might maintain synaptic long-term potentiation (LTP) and long-term memory. However, the role of PKMζ has been challenged by genetic data from PKMζ-knockout mice showing intact LTP and long-term memory. Moreover, the PKMζ inhibitor peptide ζ inhibitory peptide (ZIP) reverses LTP and erases memory in both wild-type and knockout mice. Data from four papers using additional isoform-specific genetic approaches have helped to reconcile these conflicting findings. First, a PKMζ-antisense approach showed that LTP and long-term memory in PKMζ-knockout mice are mediated through a compensatory mechanism that depends on another ZIP-sensitive atypical isoform, PKCι/λ. Second, short hairpin RNAs decreasing the amounts of individual atypical isoforms without inducing compensation disrupted memory in different temporal phases. PKCι/λ knockdown disrupted short-term memory, whereas PKMζ knockdown specifically erased long-term memory. Third, conditional PKCι/λ knockout induced compensation by rapidly activating PKMζ to preserve short-term memory. Fourth, a dominant-negative approach in the model system Aplysia revealed that multiple PKCs form PKMs to sustain different types of long-term synaptic facilitation, with atypical PKM maintaining synaptic plasticity similar to LTP. Thus, under physiological conditions, PKMζ is the principal PKC isoform that maintains LTP and long-term memory. PKCι/λ can compensate for PKMζ, and because other isoforms could also maintain synaptic facilitation, there may be a hierarchy of compensatory mechanisms maintaining memory if PKMζ malfunctions.
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Affiliation(s)
- Todd Charlton Sacktor
- Departments of Physiology & Pharmacology, Anesthesiology, and Neurology, Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, NY 11203, USA.
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA 95615, USA.
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16
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Novel calpain families and novel mechanisms for calpain regulation in Aplysia. PLoS One 2017; 12:e0186646. [PMID: 29053733 PMCID: PMC5650170 DOI: 10.1371/journal.pone.0186646] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/04/2017] [Indexed: 11/19/2022] Open
Abstract
Calpains are a family of intracellular proteases defined by a conserved protease domain. In the marine mollusk Aplysia californica, calpains are important for the induction of long-term synaptic plasticity and memory, at least in part by cleaving protein kinase Cs (PKCs) into constitutively active kinases, termed protein kinase Ms (PKMs). We identify 14 genes encoding calpains in Aplysia using bioinformatics, including at least one member of each of the four major calpain families into which metazoan calpains are generally classified, as well as additional truncated and atypical calpains. Six classical calpains containing a penta-EF-hand (PEF) domain are present in Aplysia. Phylogenetic analysis determined that these six calpains come from three separate classical calpain families. One of the classical calpains in Aplysia, AplCCal1, has been implicated in plasticity. We identify three splice cassettes and an alternative transcriptional start site in AplCCal1. We characterize several of the possible isoforms of AplCCal1 in vitro, and demonstrate that AplCCal1 can cleave PKCs into PKMs in a calcium-dependent manner in vitro. We also find that AplCCal1 has a novel mechanism of auto-inactivation through N-terminal cleavage that is modulated through its alternative transcriptional start site.
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Abstract
Memory is an adaptation to particular temporal properties of past events, such as the frequency of occurrence of a stimulus or the coincidence of multiple stimuli. In neurons, this adaptation can be understood in terms of a hierarchical system of molecular and cellular time windows, which collectively retain information from the past. We propose that this system makes various timescales of past experience simultaneously available for future adjustment of behavior. More generally, we propose that the ability to detect and respond to temporally structured information underlies the nervous system's capacity to encode and store a memory at molecular, cellular, synaptic, and circuit levels.
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Affiliation(s)
| | - Thomas James Carew
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA.
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18
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Hu J, Ferguson L, Adler K, Farah CA, Hastings MH, Sossin WS, Schacher S. Selective Erasure of Distinct Forms of Long-Term Synaptic Plasticity Underlying Different Forms of Memory in the Same Postsynaptic Neuron. Curr Biol 2017. [PMID: 28648820 DOI: 10.1016/j.cub.2017.05.081] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Generalization of fear responses to non-threatening stimuli is a feature of anxiety disorders. It has been challenging to target maladaptive generalized memories without affecting adaptive memories. Synapse-specific long-term plasticity underlying memory involves the targeting of plasticity-related proteins (PRPs) to activated synapses. If distinct tags and PRPs are used for different forms of plasticity, one could selectively remove distinct forms of memory. Using a stimulation paradigm in which associative long-term facilitation (LTF) occurs at one input and non-associative LTF at another input to the same postsynaptic neuron in an Aplysia sensorimotor preparation, we found that each form of LTF is reversed by inhibiting distinct isoforms of protein kinase M (PKM), putative PRPs, in the postsynaptic neuron. A dominant-negative (dn) atypical PKM selectively reversed associative LTF, while a dn classical PKM selectively reversed non-associative LTF. Although both PKMs are formed from calpain-mediated cleavage of protein kinase C (PKC) isoforms, each form of LTF is sensitive to a distinct dn calpain expressed in the postsynaptic neuron. Associative LTF is blocked by dn classical calpain, whereas non-associative LTF is blocked by dn small optic lobe (SOL) calpain. Interfering with a putative synaptic tag, the adaptor protein KIBRA, which protects the atypical PKM from degradation, selectively erases associative LTF. Thus, the activity of distinct PRPs and tags in a postsynaptic neuron contribute to the maintenance of different forms of synaptic plasticity at separate inputs, allowing for selective reversal of synaptic plasticity and providing a cellular basis for developing therapeutic strategies for selectively reversing maladaptive memories.
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Affiliation(s)
- Jiangyuan Hu
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute, 1051 Riverside Drive, New York, NY 10032, USA.
| | - Larissa Ferguson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Kerry Adler
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute, 1051 Riverside Drive, New York, NY 10032, USA
| | - Carole A Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Margaret H Hastings
- Department of Psychology, McGill University, Montreal Neurological Institute, Montreal, QC H3A 1B1, Canada
| | - Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Department of Psychology, McGill University, Montreal Neurological Institute, Montreal, QC H3A 1B1, Canada
| | - Samuel Schacher
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute, 1051 Riverside Drive, New York, NY 10032, USA
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Borodinova AA, Zuzina AB, Balaban PM. Role of atypical protein kinases in maintenance of long-term memory and synaptic plasticity. BIOCHEMISTRY (MOSCOW) 2017; 82:243-256. [DOI: 10.1134/s0006297917030026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Hu J, Adler K, Farah CA, Hastings MH, Sossin WS, Schacher S. Cell-Specific PKM Isoforms Contribute to the Maintenance of Different Forms of Persistent Long-Term Synaptic Plasticity. J Neurosci 2017; 37:2746-2763. [PMID: 28179558 PMCID: PMC5354326 DOI: 10.1523/jneurosci.2805-16.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 12/28/2016] [Accepted: 01/31/2017] [Indexed: 11/21/2022] Open
Abstract
Multiple kinase activations contribute to long-term synaptic plasticity, a cellular mechanism mediating long-term memory. The sensorimotor synapse of Aplysia expresses different forms of long-term facilitation (LTF)-nonassociative and associative LTF-that require the timely activation of kinases, including protein kinase C (PKC). It is not known which PKC isoforms in the sensory neuron or motor neuron L7 are required to sustain each form of LTF. We show that different PKMs, the constitutively active isoforms of PKCs generated by calpain cleavage, in the sensory neuron and L7 are required to maintain each form of LTF. Different PKMs or calpain isoforms were blocked by overexpressing specific dominant-negative constructs in either presynaptic or postsynaptic neurons. Blocking either PKM Apl I in L7, or PKM Apl II or PKM Apl III in the sensory neuron 2 d after 5-hydroxytryptamine (5-HT) treatment reversed persistent nonassociative LTF. In contrast, blocking either PKM Apl II or PKM Apl III in L7, or PKM Apl II in the sensory neuron 2 d after paired stimuli reversed persistent associative LTF. Blocking either classical calpain or atypical small optic lobe (SOL) calpain 2 d after 5-HT treatment or paired stimuli did not disrupt the maintenance of persistent LTF. Soon after 5-HT treatment or paired stimuli, however, blocking classical calpain inhibited the expression of persistent associative LTF, while blocking SOL calpain inhibited the expression of persistent nonassociative LTF. Our data suggest that different stimuli activate different calpains that generate specific sets of PKMs in each neuron whose constitutive activities sustain long-term synaptic plasticity.SIGNIFICANCE STATEMENT Persistent synaptic plasticity contributes to the maintenance of long-term memory. Although various kinases such as protein kinase C (PKC) contribute to the expression of long-term plasticity, little is known about how constitutive activation of specific kinase isoforms sustains long-term plasticity. This study provides evidence that the cell-specific activities of different PKM isoforms generated from PKCs by calpain-mediated cleavage maintain two forms of persistent synaptic plasticity, which are the cellular analogs of two forms of long-term memory. Moreover, we found that the activation of specific calpains depends on the features of the stimuli evoking the different forms of synaptic plasticity. Given the recent controversy over the role of PKMζ maintaining memory, these findings are significant in identifying roles of multiple PKMs in the retention of memory.
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Affiliation(s)
- Jiangyuan Hu
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute, New York, New York 10032,
| | - Kerry Adler
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute, New York, New York 10032
| | - Carole Abi Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada, and
| | - Margaret H Hastings
- Department of Psychology, McGill University, Montreal Neurological Institute, Montreal, Quebec H3A 1B1, Canada
| | - Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada, and
- Department of Psychology, McGill University, Montreal Neurological Institute, Montreal, Quebec H3A 1B1, Canada
| | - Samuel Schacher
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute, New York, New York 10032
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Pearce K, Cai D, Roberts AC, Glanzman DL. Role of protein synthesis and DNA methylation in the consolidation and maintenance of long-term memory in Aplysia. eLife 2017; 6. [PMID: 28067617 PMCID: PMC5310836 DOI: 10.7554/elife.18299] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 01/07/2017] [Indexed: 12/13/2022] Open
Abstract
Previously, we reported that long-term memory (LTM) in Aplysia can be reinstated by truncated (partial) training following its disruption by reconsolidation blockade and inhibition of PKM (Chen et al., 2014). Here, we report that LTM can be induced by partial training after disruption of original consolidation by protein synthesis inhibition (PSI) begun shortly after training. But when PSI occurs during training, partial training cannot subsequently establish LTM. Furthermore, we find that inhibition of DNA methyltransferase (DNMT), whether during training or shortly afterwards, blocks consolidation of LTM and prevents its subsequent induction by truncated training; moreover, later inhibition of DNMT eliminates consolidated LTM. Thus, the consolidation of LTM depends on two functionally distinct phases of protein synthesis: an early phase that appears to prime LTM; and a later phase whose successful completion is necessary for the normal expression of LTM. Both the consolidation and maintenance of LTM depend on DNA methylation.
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Affiliation(s)
- Kaycey Pearce
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, United States
| | - Diancai Cai
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, United States
| | - Adam C Roberts
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, United States
| | - David L Glanzman
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, United States.,Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, United States.,Integrative Center for Learning and Memory, Brain Research Institute, UCLA, Los Angeles, United States
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22
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Farah CA, Rourke B, Shin U, Ferguson L, Luna MJ, Sossin WS. Investigating the Potential Signaling Pathways That Regulate Activation of the Novel PKC Downstream of Serotonin in Aplysia. PLoS One 2016; 11:e0168411. [PMID: 28002451 PMCID: PMC5176290 DOI: 10.1371/journal.pone.0168411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/29/2016] [Indexed: 02/02/2023] Open
Abstract
Activation of the novel PKC Apl II in sensory neurons by serotonin (5HT) underlies the ability of 5HT to reverse synaptic depression, but the pathway from 5HT to PKC Apl II activation remains unclear. Here we find no evidence for the Aplysia-specific B receptors, or for adenylate cyclase activation, to translocate fluorescently-tagged PKC Apl II. Using an anti-PKC Apl II antibody, we monitor translocation of endogenous PKC Apl II and determine the dose response for PKC Apl II translocation, both in isolated sensory neurons and sensory neurons coupled with motor neurons. Using this assay, we confirm an important role for tyrosine kinase activation in 5HT mediated PKC Apl II translocation, but rule out roles for intracellular tyrosine kinases, epidermal growth factor (EGF) receptors and Trk kinases in this response. A partial inhibition of translocation by a fibroblast growth factor (FGF)-receptor inhibitor led us to clone the Aplysia FGF receptor. Since a number of related receptors have been recently characterized, we use bioinformatics to define the relationship between these receptors and find a single FGF receptor orthologue in Aplysia. However, expression of the FGF receptor did not affect translocation or allow it in motor neurons where 5HT does not normally cause PKC Apl II translocation. These results suggest that additional receptor tyrosine kinases (RTKs) or other molecules must also be involved in translocation of PKC Apl II.
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Affiliation(s)
- Carole A. Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Bryan Rourke
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Unkyung Shin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Larissa Ferguson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - María José Luna
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Wayne S. Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
- * E-mail:
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23
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Farah CA, Hastings MH, Dunn TW, Gong K, Baker-Andresen D, Sossin WS. A PKM generated by calpain cleavage of a classical PKC is required for activity-dependent intermediate-term facilitation in the presynaptic sensory neuron of Aplysia. ACTA ACUST UNITED AC 2016; 24:1-13. [PMID: 27980071 PMCID: PMC5159657 DOI: 10.1101/lm.043745.116] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/12/2016] [Indexed: 01/24/2023]
Abstract
Atypical PKM, a persistently active form of atypical PKC, is proposed to be a molecular memory trace, but there have been few examinations of the role of PKMs generated from other PKCs. We demonstrate that inhibitors used to inhibit PKMs generated from atypical PKCs are also effective inhibitors of other PKMs. In contrast, we demonstrate that dominant-negative PKMs show isoform-specificity. A dominant-negative PKM from the classical PKC Apl I blocks activity-dependent intermediate-term facilitation (a-ITF) when expressed in the sensory neuron, while a dominant-negative PKM from the atypical PKC Apl III does not. Consistent with a specific role for PKM Apl I in activity-dependent facilitation, live imaging FRET-based cleavage assays reveal that activity leads to cleavage of the classical PKC Apl I, but not the atypical PKC Apl III in the sensory neuron varicosities of Aplysia. In contrast, massed intermediate facilitation (m-ITF) induced by 10 min of 5HT is sufficient for cleavage of the atypical PKC Apl III in the motor neuron. Interestingly, both cleavage of PKC Apl I in the sensory neuron during a-ITF and cleavage of PKC Apl III in the motor neuron during m-ITF are inhibited by a dominant-negative form of a penta-EF hand containing classical calpain cloned from Aplysia. Consistent with a role for PKMs in plasticity, this dominant-negative calpain also blocks both a-ITF when expressed in the sensory neuron and m-ITF when expressed in the motor neuron. This study broadens the role of PKMs in synaptic plasticity in two significant ways: (i) PKMs generated from multiple isoforms of PKC, including classical isoforms, maintain memory traces; (ii) PKMs play roles in the presynaptic neuron.
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Affiliation(s)
- Carole A Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Margaret H Hastings
- Department of Psychology, McGill University, Montreal Neurological Institute, Montreal, Quebec H3A 1B1, Canada
| | - Tyler W Dunn
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Katrina Gong
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Danay Baker-Andresen
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada .,Department of Psychology, McGill University, Montreal Neurological Institute, Montreal, Quebec H3A 1B1, Canada
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24
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Differential role of calpain-dependent protein cleavage in intermediate and long-term operant memory in Aplysia. Neurobiol Learn Mem 2016; 137:134-141. [PMID: 27913293 DOI: 10.1016/j.nlm.2016.11.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 01/06/2023]
Abstract
In addition to protein synthesis, protein degradation or protein cleavage may be necessary for intermediate (ITM) and long-term memory (LTM) to remove molecular constraints, facilitate persistent kinase activity and modulate synaptic plasticity. Calpains, a family of conserved calcium dependent cysteine proteases, modulate synaptic function through protein cleavage. We used the marine mollusk Aplysia californica to investigate the in vivo role of calpains during intermediate and long-term operant memory formation using the learning that food is inedible (LFI) paradigm. A single LFI training session, in which the animal associates a specific netted seaweed with the failure to swallow, generates short (30min), intermediate (4-6h) and long-term (24h) memory. Using the calpain inhibitors calpeptin and MDL-28170, we found that ITM requires calpain activity for induction and consolidation similar to the previously reported requirements for persistent protein kinase C activity in intermediate-term LFI memory. The induction of LTM also required calpain activity. In contrast to ITM, calpain activity was not necessary for the molecular consolidation of LTM. Surprisingly, six hours after LFI training we found that calpain activity was necessary for LTM, although this is a time at which neither persistent PKC activity nor protein synthesis is required for the maintenance of long-term LFI memory. These results demonstrate that calpains function in multiple roles in vivo during associative memory formation.
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25
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Different components of conditioned food aversion memory. Brain Res 2016; 1642:104-113. [DOI: 10.1016/j.brainres.2016.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/08/2016] [Accepted: 03/10/2016] [Indexed: 12/11/2022]
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26
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Ahmed SM, Macara IG. Mechanisms of polarity protein expression control. Curr Opin Cell Biol 2016; 42:38-45. [PMID: 27092866 DOI: 10.1016/j.ceb.2016.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/03/2016] [Accepted: 04/04/2016] [Indexed: 01/09/2023]
Abstract
Polarity is a universal feature of cells during division and often at other stages of the cell cycle or after post-mitotic differentiation. A conserved machinery, present in all animals, initiates and maintains polarity. Multi-cellular animals organize themselves with respect to the axes of symmetry of the organism through the process of planar cell polarity, but many tissues also express a cell-intrinsic form of polarity, for instance to segregate the apical and basolateral membranes of epithelial cells. Although the genes and proteins involved in apical-basal polarity have been known for many years, the regulation of their expression remains ill-defined. Maintenance of the correct expression levels is essential for normal cell lineage allocation, tissue morphogenesis and cell survival. Here we summarize what is known about the transcriptional and post-transcriptional regulation of polarity protein expression, and discuss areas that remain to be understood.
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Affiliation(s)
- Syed Mukhtar Ahmed
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
| | - Ian G Macara
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA.
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27
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Ierusalimsky VN, Borodinova AA, Balaban PM. Localization of the atypical protein kinase Cζ in the Nervous System of the terrestrial snail Helix. NEUROCHEM J+ 2015. [DOI: 10.1134/s1819712415040091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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28
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Balaban PM, Roshchin M, Timoshenko AK, Zuzina AB, Lemak M, Ierusalimsky VN, Aseyev NA, Malyshev AY. Homolog of protein kinase Mζ maintains context aversive memory and underlying long-term facilitation in terrestrial snail Helix. Front Cell Neurosci 2015; 9:222. [PMID: 26157359 PMCID: PMC4475826 DOI: 10.3389/fncel.2015.00222] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/26/2015] [Indexed: 11/25/2022] Open
Abstract
It has been shown that a variety of long-term memories in different regions of the brain and in different species are quickly erased by local inhibition of protein kinase Mζ (PKMζ), a persistently active protein kinase. Using antibodies to mammalian PKMζ, we describe in the present study the localization of immunoreactive molecules in the nervous system of the terrestrial snail Helix lucorum. Presence of a homolog of PKMζ was confirmed with transcriptomics. We have demonstrated in behavioral experiments that contextual fear memory disappeared under a blockade of PKMζ with a selective peptide blocker of PKMζ zeta inhibitory peptide (ZIP), but not with scrambled ZIP. If ZIP was combined with a “reminder” (20 min in noxious context), no impairment of the long-term contextual memory was observed. In electrophysiological experiments we investigated whether PKMζ takes part in the maintenance of long-term facilitation (LTF) in the neural circuit mediating tentacle withdrawal. LTF of excitatory synaptic inputs to premotor interneurons was induced by high-frequency nerve stimulation combined with serotonin bath applications and lasted at least 4 h. We found that bath application of 2 × 10−6 M ZIP at the 90th min after the tetanization reduced the EPSP amplitude to the non-tetanized EPSP values. Applications of the scrambled ZIP peptide at a similar time and concentration didn’t affect the EPSP amplitudes. In order to test whether effects of ZIP are specific to the synapses, we performed experiments with LTF of somatic membrane responses to local glutamate applications. It was shown earlier that serotonin application in such an “artificial synapse” condition elicits LTF of responses to glutamate. It was found that ZIP had no effect on LTF in these conditions, which may be explained by the very low concentration of PKMζ molecules in somata of these identified neurons, as evidenced by immunochemistry. Obtained results suggest that the Helix homolog of PKMζ might be involved in post-induction maintenance of long-term changes in the nervous system of the terrestrial snail.
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Affiliation(s)
- Pavel M Balaban
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia ; Biology Department, Lomonosov Moscow State University Moscow, Russia
| | - Matvey Roshchin
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia
| | - Alia Kh Timoshenko
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia
| | - Alena B Zuzina
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia ; Biology Department, Lomonosov Moscow State University Moscow, Russia
| | - Maria Lemak
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia
| | - Victor N Ierusalimsky
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia
| | - Nikolay A Aseyev
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia
| | - Aleksey Y Malyshev
- Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences Moscow, Russia
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Fiumara F, Rajasethupathy P, Antonov I, Kosmidis S, Sossin WS, Kandel ER. MicroRNA-22 Gates Long-Term Heterosynaptic Plasticity in Aplysia through Presynaptic Regulation of CPEB and Downstream Targets. Cell Rep 2015; 11:1866-75. [DOI: 10.1016/j.celrep.2015.05.034] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 03/12/2015] [Accepted: 05/19/2015] [Indexed: 12/12/2022] Open
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30
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Byrne JH, Hawkins RD. Nonassociative learning in invertebrates. Cold Spring Harb Perspect Biol 2015; 7:cshperspect.a021675. [PMID: 25722464 DOI: 10.1101/cshperspect.a021675] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The simplicity and tractability of the neural circuits mediating behaviors in invertebrates have facilitated the cellular/molecular dissection of neural mechanisms underlying learning. The review has a particular focus on the general principles that have emerged from analyses of an example of nonassociative learning, sensitization in the marine mollusk Aplysia. Learning and memory rely on multiple mechanisms of plasticity at multiple sites of the neuronal circuits, with the relative contribution to memory of the different sites varying as a function of the extent of training and time after training. The same intracellular signaling cascades that induce short-term modifications in synaptic transmission can also be used to induce long-term changes. Although short-term memory relies on covalent modifications of preexisting proteins, long-term memory also requires regulated gene transcription and translation. Maintenance of long-term cellular memory involves both intracellular and extracellular feedback loops, which sustain the regulation of gene expression and the modification of targeted molecules.
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Affiliation(s)
- John H Byrne
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas 77030
| | - Robert D Hawkins
- Department of Neuroscience, Columbia University, New York, New York 10032 New York State Psychiatric Institute, New York, New York 10032
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31
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Moretti D, Del Bello B, Allavena G, Maellaro E. Calpains and cancer: Friends or enemies? Arch Biochem Biophys 2014; 564:26-36. [DOI: 10.1016/j.abb.2014.09.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 09/23/2014] [Accepted: 09/30/2014] [Indexed: 02/07/2023]
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32
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Deng Z, Lubinski AJ, Page TL. Zeta inhibitory peptide (ZIP) erases long-term memories in a cockroach. Neurobiol Learn Mem 2014; 118:89-95. [PMID: 25434819 DOI: 10.1016/j.nlm.2014.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/11/2014] [Accepted: 11/21/2014] [Indexed: 12/20/2022]
Abstract
Recent efforts to identify the molecules that are involved in the maintenance of long-term memories in mammals have focused attention on atypical isoforms of protein kinase C (PKC). Inhibition of these kinases by either the general PKC inhibitor, chelerythrine, or the more specific inhibitor, zeta inhibitory peptide (ZIP), can abolish both long-term potentiation in the hippocampus and as well as spatial, fear, appetitive, and sensorimotor memories. These inhibitors can also abolish long-term facilitation and long-term sensitization in the mollusk Aplysia californica. We have extended these results to an insect, the cockroach Leucophaea maderae. We show that systemic injections of either chelerythrine or ZIP erase long-term olfactory memories in the cockroach, but have no effect on memory acquisition during conditioning. We also show that inhibition of either protein kinase A (PKA) or protein synthesis can block memory acquisition but neither has an effect on the memory once it is formed. The results suggest that sustaining memories in insects requires the persistent activity of one or more isoforms of PKC and point to a strong evolutionary conservation of the molecular mechanisms that underlie the persistence of long-term memories in the central nervous system.
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Affiliation(s)
- Zhouheng Deng
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, United States
| | - Alexander J Lubinski
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, United States
| | - Terry L Page
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, United States.
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Chen S, Cai D, Pearce K, Sun PYW, Roberts AC, Glanzman DL. Reinstatement of long-term memory following erasure of its behavioral and synaptic expression in Aplysia. eLife 2014; 3:e03896. [PMID: 25402831 PMCID: PMC4270066 DOI: 10.7554/elife.03896] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 11/13/2014] [Indexed: 12/29/2022] Open
Abstract
Long-term memory (LTM) is believed to be stored in the brain as changes in synaptic connections. Here, we show that LTM storage and synaptic change can be dissociated. Cocultures of Aplysia sensory and motor neurons were trained with spaced pulses of serotonin, which induces long-term facilitation. Serotonin (5HT) triggered growth of new presynaptic varicosities, a synaptic mechanism of long-term sensitization. Following 5HT training, two antimnemonic treatments-reconsolidation blockade and inhibition of PKM--caused the number of presynaptic varicosities to revert to the original, pretraining value. Surprisingly, the final synaptic structure was not achieved by targeted retraction of the 5HT-induced varicosities but, rather, by an apparently arbitrary retraction of both 5HT-induced and original synapses. In addition, we find evidence that the LTM for sensitization persists covertly after its apparent elimination by the same antimnemonic treatments that erase learning-related synaptic growth. These results challenge the idea that stable synapses store long-term memories.
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Affiliation(s)
- Shanping Chen
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, United States
| | - Diancai Cai
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, United States
| | - Kaycey Pearce
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, United States
| | - Philip Y-W Sun
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, United States
| | - Adam C Roberts
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, United States
| | - David L Glanzman
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, United States
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, United States
- Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, United States
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Zhou L, Baxter DA, Byrne JH. Contribution of PKC to the maintenance of 5-HT-induced short-term facilitation at sensorimotor synapses of Aplysia. J Neurophysiol 2014; 112:1936-49. [PMID: 25031258 DOI: 10.1152/jn.00577.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aplysia sensorimotor synapses provide a useful model system for analyzing molecular processes that contribute to heterosynaptic plasticity. For example, previous studies demonstrated that multiple kinase cascades contribute to serotonin (5-HT)-induced short-term synaptic facilitation (STF), including protein kinase A (PKA) and protein kinase C (PKC). Moreover, the contribution of each kinase is believed to depend on the state of the synapse (e.g., depressed or nondepressed) and the time after application of 5-HT. Here, a previously unappreciated role for PKC-dependent processes was revealed to underlie the maintenance of STF at relatively nondepressed synapses. This PKC dependence was revealed when the synapse was stimulated repeatedly after application of 5-HT. The contributions of the PKA and PKC pathways were examined by blocking adenylyl cyclase-coupled 5-HT receptors with methiothepin and by blocking PKC with chelerythrine. STF was assessed 20 s after 5-HT application. The effects of PKC were consistent with enhanced mobilization of transmitter, as assessed by application of hypertonic sucrose solutions to measure the readily releasable pool of vesicles and recovery of the readily releasable pool after depletion. A computational model of transmitter release demonstrated that a PKC-dependent mobilization process was sufficient to explain the maintenance of STF at nondepressed synapses and the facilitation of depressed synapses.
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Affiliation(s)
- Lian Zhou
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas
| | - Douglas A Baxter
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas
| | - John H Byrne
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas
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PKCζ and PKMζ are overexpressed in TCF3-rearranged paediatric acute lymphoblastic leukaemia and are associated with increased thiopurine sensitivity. Leukemia 2014; 29:304-11. [PMID: 24990612 PMCID: PMC4320296 DOI: 10.1038/leu.2014.210] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 12/11/2022]
Abstract
Both tumour suppressor and oncogenic functions have been ascribed to the atypical zeta isoform of protein kinase C (PKCζ), whereas its constitutively active form PKMζ is almost exclusively expressed in the brain where it has a role in long-term memory. Using primers unique for either isoform, we found that both PKCζ and PKMζ were expressed in a subset of paediatric acute lymphoblastic leukaemia (ALL) cases carrying a TCF3 (E2A) chromosomal rearrangement. Combined PKCζ and PKMζ (PKC/Mζ) protein as well as phosphorylation levels were elevated in ALL cases, especially TCF3-rearranged precursor B-ALL cases, compared with normal bone marrow (P<0.01). Furthermore, high PKC/Mζ expression in primary ALL cells was associated with increased sensitivity to 6-thioguanine and 6-mercaptopurine (P<0.01), thiopurines used in ALL treatment. PKCζ is believed to stabilize mismatch-repair protein MSH2, facilitating thiopurine responsiveness in T-ALL. However, PKC/Mζ knockdown in a TCF3-rearranged cell line model decreased MSH2 expression but did not induce thiopurine resistance, indicative that the link between high PKC/Mζ levels and thiopurine sensitivity in paediatric precursor B-ALL is not directly causal. Collectively, our data indicate that thiopurine treatment may be effective, especially in paediatric TCF3-rearranged ALL and other patients with a high expression of PKC/Mζ.
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Rahn EJ, Guzman-Karlsson MC, David Sweatt J. Cellular, molecular, and epigenetic mechanisms in non-associative conditioning: implications for pain and memory. Neurobiol Learn Mem 2013; 105:133-50. [PMID: 23796633 DOI: 10.1016/j.nlm.2013.06.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 06/10/2013] [Accepted: 06/11/2013] [Indexed: 01/09/2023]
Abstract
Sensitization is a form of non-associative conditioning in which amplification of behavioral responses can occur following presentation of an aversive or noxious stimulus. Understanding the cellular and molecular underpinnings of sensitization has been an overarching theme spanning the field of learning and memory as well as that of pain research. In this review we examine how sensitization, both in the context of learning as well as pain processing, shares evolutionarily conserved behavioral, cellular/synaptic, and epigenetic mechanisms across phyla. First, we characterize the behavioral phenomenon of sensitization both in invertebrates and vertebrates. Particular emphasis is placed on long-term sensitization (LTS) of withdrawal reflexes in Aplysia following aversive stimulation or injury, although additional invertebrate models are also covered. In the context of vertebrates, sensitization of mammalian hyperarousal in a model of post-traumatic stress disorder (PTSD), as well as mammalian models of inflammatory and neuropathic pain is characterized. Second, we investigate the cellular and synaptic mechanisms underlying these behaviors. We focus our discussion on serotonin-mediated long-term facilitation (LTF) and axotomy-mediated long-term hyperexcitability (LTH) in reduced Aplysia systems, as well as mammalian spinal plasticity mechanisms of central sensitization. Third, we explore recent evidence implicating epigenetic mechanisms in learning- and pain-related sensitization. This review illustrates the fundamental and functional overlay of the learning and memory field with the pain field which argues for homologous persistent plasticity mechanisms in response to sensitizing stimuli or injury across phyla.
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Affiliation(s)
- Elizabeth J Rahn
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
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Abstract
Low-frequency depression (LFD) of transmitter release occurs at phasic synapses with stimulation at 0.2 Hz in both isolated crayfish (Procambarus clarkii) neuromuscular junction (NMJ) preparations and in intact animals. LFD is regulated by presynaptic activity of the Ca(2+)-dependent phosphatase calcineurin (Silverman-Gavrila and Charlton, 2009). Since the fast Ca(2+) chelator BAPTA-AM inhibits LFD but the slow chelator EGTA-AM does not, the Ca(2+) sensor for LFD may be close to a Ca(2+) source at active zones. Calcineurin can be activated by the Ca(2+)-activated protease calpain, and immunostaining showed that both proteins are present at nerve terminals. Three calpain inhibitors, calpain inhibitor I, MDL-28170, and PD150606, but not the control compound PD145305, inhibit LFD both in the intact animal as shown by electromyograms and by intracellular recordings at neuromuscular junctions. Analysis of mini-EPSPs indicated that these inhibitors had minimal postsynaptic effects. Proteolytic activity in CNS extract, detected by a fluorescent calpain substrate, was modulated by Ca(2+) and calpain inhibitors. Western blot analysis of CNS extract showed that proteolysis of calcineurin to a fragment consistent with the constitutively active form required Ca(2+) and was blocked by calpain inhibitors. Inhibition of LFD by calpain inhibition blocks the reduction in phosphoactin and the depolymerization of tubulin that normally occurs in LFD, probably by blocking the dephosphorylation of cytoskeletal proteins by calcineurin. In contrast, high-frequency depression does not involve protein phosphorylation- or calpain-dependent mechanisms. LFD may involve a specific pathway in which local Ca(2+) signaling activates presynaptic calpain and calcineurin at active zones and causes changes of tubulin cytoskeleton.
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Abstract
How can memories outlast the molecules from which they are made? Answers to this fundamental question have been slow coming but are now emerging. A novel kinase, an isoform of protein kinase C (PKC), PKMzeta, has been shown to be critical to the maintenance of some types of memory. Inhibiting the catalytic properties of this kinase can erase well-established memories without altering the ability of the erased synapse to be retrained. This article provides an overview of the literature linking PKMzeta to memory maintenance and identifies some of the controversial issues that surround the bold implications of the existing data. It concludes with a discussion of the future directions of this domain.
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Affiliation(s)
- David L Glanzman
- Department of Integrative Biology and Physiology, University of California Los Angeles, CA, 90095 USA ; Department of Neurobiology and the Brain Research Institute, David Geffen School of Medicine, University of California Los Angeles, CA, 90095 USA ; Integrative Center for Learning and Memory, University of California Los Angeles, CA, 90095 USA
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Abstract
A constitutively active kinase, known as protein kinase Mζ (PKMζ), is proposed to act as a long-lasting molecular memory trace. While PKMζ is formed in rodents through translation of a transcript initiating in an intron of the protein kinase Cζ (PKCζ) gene, this transcript does not exist in Aplysia californica despite the fact that inhibitors of PKMζ erase memory in Aplysia in a fashion similar to rodents. We have previously shown that, in Aplysia, the ortholog of PKCζ, PKC Apl III, is cleaved by calpain to form a PKM after overexpression of PKC Apl III. We now show that kinase activity is required for this cleavage. We further use a FRET reporter to measure cleavage of PKC Apl III into PKM Apl III in live neurons using a stimulus that induces plasticity. Our results show that a 10 min application of serotonin induces cleavage of PKC Apl III in motor neuron processes in a calpain- and protein synthesis-dependent manner, but does not induce cleavage of PKC Apl III in sensory neuron processes. Furthermore, a dominant-negative PKM Apl III expressed in the motor neuron blocked the late phase of intermediate-term facilitation in sensory-motor neuron cocultures induced by 10 min of serotonin. In summary, we provide evidence that PKC Apl III is cleaved into PKM Apl III during memory formation, that the requirements for cleavage are the same as the requirements for the plasticity, and that PKM in the motor neuron is required for intermediate-term facilitation.
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Roles of Protein Kinase C and Protein Kinase M in Aplysia Learning. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-12-415823-8.00018-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Sacktor TC. Memory maintenance by PKMζ--an evolutionary perspective. Mol Brain 2012; 5:31. [PMID: 22986281 PMCID: PMC3517905 DOI: 10.1186/1756-6606-5-31] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 08/29/2012] [Indexed: 11/20/2022] Open
Abstract
Long-term memory is believed to be maintained by persistent modifications of synaptic transmission within the neural circuits that mediate behavior. Thus, long-term potentiation (LTP) is widely studied as a potential physiological basis for the persistent enhancement of synaptic strength that might sustain memory. Whereas the molecular mechanisms that initially induce LTP have been extensively characterized, the mechanisms that persistently maintain the potentiation have not. Recently, however, a candidate molecular mechanism linking the maintenance of LTP and the storage of long-term memory has been identified. The persistent activity of the autonomously active, atypical protein kinase C (aPKC) isoform, PKMζ, is both necessary and sufficient for maintaining LTP. Furthermore, blocking PKMζ activity by pharmacological or dominant negative inhibitors disrupts previously stored long-term memories in a variety of neural circuits, including spatial and trace memories in the hippocampus, aversive memories in the basolateral amygdala, appetitive memories in the nucleus accumbens, habit memory in the dorsal lateral striatum, and elementary associations, extinction, and skilled sensorimotor memories in the neocortex. During LTP and memory formation, PKMζ is synthesized de novo as a constitutively active kinase. This molecular mechanism for memory storage is evolutionarily conserved. PKMζ formation through new protein synthesis likely originated in early vertebrates ~500 million years ago during the Cambrian period. Other mechanisms for forming persistently active PKM from aPKC are found in invertebrates, and inhibiting this atypical PKM disrupts long-term memory in the invertebrate model systems Drosophila melanogaster and Aplysia californica. Conversely, overexpressing PKMζ enhances memory in flies and rodents. PKMζ persistently enhances synaptic strength by maintaining increased numbers of AMPA receptors at postsynaptic sites, a mechanism that might have evolved from the general function of aPKC in trafficking membrane proteins to the apical compartment of polarized cells. This mechanism of memory may have had adaptive advantages because it is both stable and reversible, as demonstrated by the downregulation of experience-dependent, long-term increases in PKMζ after extinction and reconsolidation blockade that attenuate learned behavior. Thus, PKMζ, the “working end” of LTP, is a component of an evolutionarily conserved molecular mechanism for the persistent, yet flexible storage of long-term memory.
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Affiliation(s)
- Todd Charlton Sacktor
- The Robert F. Furchgott Center for Neural and Behavioral Science, Department of Physiology, State University of New York Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 10705, USA.
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Cai D, Pearce K, Chen S, Glanzman DL. Reconsolidation of long-term memory in Aplysia. Curr Biol 2012; 22:1783-8. [PMID: 22885063 DOI: 10.1016/j.cub.2012.07.038] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 06/15/2012] [Accepted: 07/16/2012] [Indexed: 10/28/2022]
Abstract
When an animal is reminded of a prior experience and shortly afterward treated with a protein synthesis inhibitor, the consolidated memory for the experience can be disrupted; by contrast, protein synthesis inhibition without prior reminding commonly does not disrupt long-term memory [1-3]. Such results imply that the reminding triggers reconsolidation of the memory. Here, we asked whether the behavioral and synaptic changes associated with the memory for long-term sensitization (LTS) of the siphon-withdrawal reflex in the marine snail Aplysia californica [4, 5] could undergo reconsolidation. In support of this idea, we found that when sensitized animals were given abbreviated reminder sensitization training 48-96 hr after the original sensitization training, followed by treatment with the protein synthesis inhibitor anisomycin, LTS was disrupted. We also found that long-term (≥ 24 hr) facilitation (LTF) [6], which can be induced in the monosynaptic connection between Aplysia sensory and motor neurons in dissociated cell culture by multiple spaced pulses of the endogenous facilitatory transmitter serotonin (5-HT) [7, 8], could be eliminated by treating the synapses with one reminder pulse of 5-HT, followed by anisomycin, at 48 hr after the original training. Our results provide a simple model system for understanding the synaptic basis of reconsolidation.
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Affiliation(s)
- Diancai Cai
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
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Wan Q, Jiang XY, Negroiu AM, Lu SG, McKay KS, Abrams TW. Protein kinase C acts as a molecular detector of firing patterns to mediate sensory gating in Aplysia. Nat Neurosci 2012; 15:1144-52. [PMID: 22772333 PMCID: PMC4228944 DOI: 10.1038/nn.3158] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 06/06/2012] [Indexed: 11/24/2022]
Abstract
Habituation of a behavioral response to a repetitive stimulus enables animals to ignore irrelevant stimuli and focus on behaviorally important events. In Aplysia, habituation is mediated by rapid depression of sensory synapses, which could leave an animal unresponsive to important repetitive stimuli, making it vulnerable to injury. We identified a form of plasticity that prevents synaptic depression depending on the precise stimulus strength. Burst-dependent protection from depression is initiated by trains of 2-4 action potentials and is distinct from previously described forms of synaptic enhancement. The blockade of depression is mediated by presynaptic Ca2+ influx and protein kinase C (PKC) and requires localization of PKC via a PDZ domain interaction with Aplysia PICK1. During protection from depression, PKC acts as a highly sensitive detector of the precise pattern of sensory neuron firing. Behaviorally, burst-dependent protection reduces habituation, enabling animals to maintain responsiveness to stimuli that are functionally important.
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Affiliation(s)
- Qin Wan
- Department of Pharmacology, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201-1559
| | - Xue-Ying Jiang
- Department of Pharmacology, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201-1559
| | - Andreea M. Negroiu
- Department of Pharmacology, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201-1559
| | - Shao-Gang Lu
- Department of Pharmacology, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201-1559
| | - Kimberly S. McKay
- Program in Neuroscience, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201-1559
| | - Thomas W. Abrams
- Department of Pharmacology, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201-1559
- Program in Neuroscience, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201-1559
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Massed training-induced intermediate-term operant memory in aplysia requires protein synthesis and multiple persistent kinase cascades. J Neurosci 2012; 32:4581-91. [PMID: 22457504 DOI: 10.1523/jneurosci.6264-11.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The Aplysia feeding system with its high degree of plasticity and well characterized neuronal circuitry is well suited for investigations of memory formation. We used an operant paradigm, learning that food is inedible (LFI), to investigate the signaling pathways underlying intermediate-term memory (ITM) in Aplysia. During a single massed training session, the animal associates a specific seaweed with the failure to swallow, generating short-term (30 min) and long-term (24 h) memory. We investigated whether the same training protocol induced the formation of ITM. We found that massed LFI training resulted in temporally distinct protein synthesis-dependent memory evident 4-6 h after training. Through in vivo experiments, we determined that the formation of ITM required protein kinase A, protein kinase C, and MAPK. Moreover, the maintenance of ITM required PKA, PKM Apl III, and MAPK because inhibition of any of these kinases after training or before testing blocked the expression of memory. In contrast, additional experiments determined that the maintenance of long-term memory appeared independent of PKM Apl III. Using Western blotting, we found that sustained MAPK phosphorylation was dependent upon protein synthesis, but not PKA or PKC activity. Thus, massed training-induced intermediate-term operant memory requires protein synthesis as well as persistent or sustained kinase signaling for PKA, PKC, and MAPK. While short-, intermediate-, and long-term memory are induced by the same training protocol, considerable differences exist in both the combination and timing of signaling cascades that induce the formation and maintenance of these temporally distinct memories.
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Mapping Molecular Memory: Navigating the Cellular Pathways of Learning. Cell Mol Neurobiol 2012; 32:919-41. [DOI: 10.1007/s10571-012-9836-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 03/21/2012] [Indexed: 01/25/2023]
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Persistent long-term synaptic plasticity requires activation of a new signaling pathway by additional stimuli. J Neurosci 2011; 31:8841-50. [PMID: 21677168 DOI: 10.1523/jneurosci.1358-11.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Most memories are strengthened by additional stimuli, but it is unclear how additional stimulation or training reinforces long-term memory. To address this we examined whether long-term facilitation (LTF) of Aplysia sensorimotor synapses in cell culture-a cellular correlate of long-term sensitization of defensive withdrawal reflexes in Aplysia californica-can be prolonged by additional stimulation. We found that 1 d treatment with serotonin (5-HT; five brief applications at 20 min intervals) produced LTF lasting ∼3 d, whereas 2 d of such 5-HT treatments induced a persistent LTF lasting >7 d. Incubation with the protein synthesis inhibitor rapamycin during the second set of 5-HT treatments abolished all facilitation, and synapse strength returned prematurely to baseline. Persistent LTF required more persistent elevation in the expression of the neurotrophin-like peptide sensorin and its secretion. Activation of protein kinase C (PKC) during the second day of 5-HT treatments, not required for LTF or changes in sensorin expression during the first set of 5-HT treatments, is critical for persistent LTF and replaces phosphoinositide 3 kinase (PI3K) activity in mediating the increase in sensorin expression. In contrast, activations of PKC during the first day of 5-HT treatments and PI3K during the second day of 5-HT treatments are unnecessary for persistent LTF or the increases in sensorin expression. Thus, additional stimuli make preexisting plasticity labile as they recruit a new signaling cascade to regulate the synthesis of a neurotrophin-like peptide required for persistent alterations in synaptic efficacy.
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Abstract
How the brain maintains long-term memories is one of the major outstanding questions in modern neuroscience. Evidence from mammalian studies indicates that activity of a protein kinase C (PKC) isoform, protein kinase Mζ (PKMζ), plays a critical role in the maintenance of long-term memory. But the range of memories whose persistence depends on PKMζ, and the mechanisms that underlie the effect of PKMζ on long-term memory, remain obscure. Recently, a PKM isoform, known as PKM Apl III, was cloned from the nervous system of Aplysia. Here, we tested whether PKM Apl III plays a critical role in long-term memory maintenance in Aplysia. Intrahemocoel injections of the pseudosubstrate inhibitory peptide ZIP (ζ inhibitory peptide) or the PKC inhibitor chelerythrine erased the memory for long-term sensitization (LTS) of the siphon-withdrawal reflex (SWR) as late as 7 d after training. In addition, both PKM inhibitors disrupted the maintenance of long-term (≥ 24 h) facilitation (LTF) of the sensorimotor synapse, a form of synaptic plasticity previously shown to mediate LTS of the SWR. Together with previous results (Bougie et al., 2009), our results support the idea that long-term memory in Aplysia is maintained via a positive-feedback loop involving PKM Apl III-dependent protein phosphorylation. The present data extend the known role of PKM in memory maintenance to a simple and well studied type of long-term learning. Furthermore, the demonstration that PKM activity underlies the persistence of LTF of the Aplysia sensorimotor synapse, a form of synaptic plasticity amenable to rigorous cellular and molecular analyses, should facilitate efforts to understand how PKM activity maintains memory.
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GPS-CCD: a novel computational program for the prediction of calpain cleavage sites. PLoS One 2011; 6:e19001. [PMID: 21533053 PMCID: PMC3080405 DOI: 10.1371/journal.pone.0019001] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 03/21/2011] [Indexed: 11/19/2022] Open
Abstract
As one of the most essential post-translational modifications (PTMs) of proteins, proteolysis, especially calpain-mediated cleavage, plays an important role in many biological processes, including cell death/apoptosis, cytoskeletal remodeling, and the cell cycle. Experimental identification of calpain targets with bona fide cleavage sites is fundamental for dissecting the molecular mechanisms and biological roles of calpain cleavage. In contrast to time-consuming and labor-intensive experimental approaches, computational prediction of calpain cleavage sites might more cheaply and readily provide useful information for further experimental investigation. In this work, we constructed a novel software package of GPS-CCD (Calpain Cleavage Detector) for the prediction of calpain cleavage sites, with an accuracy of 89.98%, sensitivity of 60.87% and specificity of 90.07%. With this software, we annotated potential calpain cleavage sites for hundreds of calpain substrates, for which the exact cleavage sites had not been previously determined. In this regard, GPS-CCD 1.0 is considered to be a useful tool for experimentalists. The online service and local packages of GPS-CCD 1.0 were implemented in JAVA and are freely available at: http://ccd.biocuckoo.org/.
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Cortesio CL, Boateng LR, Piazza TM, Bennin DA, Huttenlocher A. Calpain-mediated proteolysis of paxillin negatively regulates focal adhesion dynamics and cell migration. J Biol Chem 2011; 286:9998-10006. [PMID: 21270128 DOI: 10.1074/jbc.m110.187294] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The dynamic turnover of integrin-mediated adhesions is important for cell migration. Paxillin is an adaptor protein that localizes to focal adhesions and has been implicated in cell motility. We previously reported that calpain-mediated proteolysis of talin1 and focal adhesion kinase mediates adhesion disassembly in motile cells. To determine whether calpain-mediated paxillin proteolysis regulates focal adhesion dynamics and cell motility, we mapped the preferred calpain proteolytic site in paxillin. The cleavage site is between the paxillin LD1 and LD2 motifs and generates a C-terminal fragment that is similar in size to the alternative product paxillin delta. The calpain-generated proteolytic fragment, like paxillin delta, functions as a paxillin antagonist and impairs focal adhesion disassembly and migration. We generated mutant paxillin with a point mutation (S95G) that renders it partially resistant to calpain proteolysis. Paxillin-deficient cells that express paxillin S95G display increased turnover of zyxin-containing adhesions using time-lapse microscopy and also show increased migration. Moreover, cancer-associated somatic mutations in paxillin are common in the N-terminal region between the LD1 and LD2 motifs and confer partial calpain resistance. Taken together, these findings suggest a novel role for calpain-mediated proteolysis of paxillin as a negative regulator of focal adhesion dynamics and migration that may function to limit cancer cell invasion.
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Affiliation(s)
- Christa L Cortesio
- Department of Biomolecular Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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50
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Jin I, Kandel ER, Hawkins RD. Whereas short-term facilitation is presynaptic, intermediate-term facilitation involves both presynaptic and postsynaptic protein kinases and protein synthesis. Learn Mem 2011; 18:96-102. [PMID: 21245210 DOI: 10.1101/lm.1949711] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Whereas short-term plasticity involves covalent modifications that are generally restricted to either presynaptic or postsynaptic structures, long-term plasticity involves the growth of new synapses, which by its nature involves both pre- and postsynaptic alterations. In addition, an intermediate-term stage of plasticity has been identified that might form a bridge between short- and long-term plasticity. Consistent with that idea, although short-term term behavioral sensitization in Aplysia involves presynaptic mechanisms, intermediate-term sensitization involves both pre- and postsynaptic mechanisms. However, it has not been known whether that is also true of facilitation in vitro, where a more detailed analysis of the mechanisms involved in the different stages and their interrelations is feasible. To address those questions, we have examined pre- and postsynaptic mechanisms of short- and intermediate-term facilitation at Aplysia sensory-motor neuron synapses in isolated cell culture. Whereas short-term facilitation by 1-min 5-HT involves presynaptic PKA and CamKII, intermediate-term facilitation by 10-min 5-HT involves presynaptic PKC and postsynaptic Ca(2+) and CamKII, as well as both pre- and postsynaptic protein synthesis. These results support the idea that the intermediate-term stage is the first to involve both pre- and postsynaptic molecular mechanisms, which could in turn serve as some of the initial steps in a cascade leading to synaptic growth during long-term plasticity.
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Affiliation(s)
- Iksung Jin
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
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