Key publications
Bourgognon J-M, Schiavon E, Salah-Uddin H, Skrzypiec AE, Attwood BK, Shah RS, Patel SG, Mucha M, John Challiss RA, Forsythe ID, et al (2013). Regulation of neuronal plasticity and fear by a dynamic change in PAR1-G protein coupling in the amygdala.
Mol Psychiatry,
18(10), 1136-1145.
Abstract:
Regulation of neuronal plasticity and fear by a dynamic change in PAR1-G protein coupling in the amygdala.
Fear memories are acquired through neuronal plasticity, an orchestrated sequence of events regulated at circuit and cellular levels. The conventional model of fear acquisition assumes unimodal (for example, excitatory or inhibitory) roles of modulatory receptors in controlling neuronal activity and learning. Contrary to this view, we show that protease-activated receptor-1 (PAR1) promotes contrasting neuronal responses depending on the emotional status of an animal by a dynamic shift between distinct G protein-coupling partners. In the basolateral amygdala of fear-naive mice PAR1 couples to Gαq/11 and Gαo proteins, while after fear conditioning coupling to Gαo increases. Concurrently, stimulation of PAR1 before conditioning enhanced, but afterwards it inhibited firing of basal amygdala neurons. An initial impairment of the long-term potentiation (LTP) in PAR1-deficient mice was transformed into an increase in LTP and enhancement of fear after conditioning. These effects correlated with more frequent 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid (AMPA) receptor-mediated miniature post synaptic events and increased neuronal excitability. Our findings point to experience-specific shifts in PAR1-G protein coupling in the amygdala as a novel mechanism regulating neuronal excitability and fear.
Abstract.
Author URL.
Mucha M, Skrzypiec AE, Schiavon E, Attwood BK, Kucerova E, Pawlak R (2011). Lipocalin-2 controls neuronal excitability and anxiety by regulating dendritic spine formation and maturation.
Proc Natl Acad Sci U S A,
108(45), 18436-18441.
Abstract:
Lipocalin-2 controls neuronal excitability and anxiety by regulating dendritic spine formation and maturation.
Psychological stress causes adaptive changes in the nervous system directed toward maintaining homoeostasis. These biochemical and structural mechanisms regulate animal behavior, and their malfunction may result in various forms of affective disorders. Here we found that the lipocalin-2 (Lcn2) gene, encoding a secreted protein of unknown neuronal function, was up-regulated in mouse hippocampus following psychological stress. Addition of lipocalin-2 to cultured hippocampal neurons reduced dendritic spine actin's mobility, caused retraction of mushroom spines, and inhibited spine maturation. These effects were further enhanced by inactivating iron-binding residues of Lcn-2, suggesting that they were facilitated by the iron-free form of Lcn-2. Concurrently, disruption of the Lcn2 gene in mice promoted stress-induced increase in spine density and caused an increase in the proportion of mushroom spines. The above changes correlated with higher excitability of CA1 principal neurons and with elevated stress-induced anxiety in Lcn-2(-/-) mice. Our study demonstrates that lipocalin-2 promotes stress-induced changes in spine morphology and function to regulate neuronal excitability and anxiety.
Abstract.
Author URL.
Attwood BK, Bourgognon J-M, Patel S, Mucha M, Schiavon E, Skrzypiec AE, Young KW, Shiosaka S, Korostynski M, Piechota M, et al (2011). Neuropsin cleaves EphB2 in the amygdala to control anxiety.
Nature,
473(7347), 372-375.
Abstract:
Neuropsin cleaves EphB2 in the amygdala to control anxiety.
A minority of individuals experiencing traumatic events develop anxiety disorders. The reason for the lack of correspondence between the prevalence of exposure to psychological trauma and the development of anxiety is unknown. Extracellular proteolysis contributes to fear-associated responses by facilitating neuronal plasticity at the neuron-matrix interface. Here we show in mice that the serine protease neuropsin is critical for stress-related plasticity in the amygdala by regulating the dynamics of the EphB2-NMDA-receptor interaction, the expression of Fkbp5 and anxiety-like behaviour. Stress results in neuropsin-dependent cleavage of EphB2 in the amygdala causing dissociation of EphB2 from the NR1 subunit of the NMDA receptor and promoting membrane turnover of EphB2 receptors. Dynamic EphB2-NR1 interaction enhances NMDA receptor current, induces Fkbp5 gene expression and enhances behavioural signatures of anxiety. On stress, neuropsin-deficient mice do not show EphB2 cleavage and its dissociation from NR1 resulting in a static EphB2-NR1 interaction, attenuated induction of the Fkbp5 gene and low anxiety. The behavioural response to stress can be restored by intra-amygdala injection of neuropsin into neuropsin-deficient mice and disrupted by the injection of either anti-EphB2 antibodies or silencing the Fkbp5 gene in the amygdala of wild-type mice. Our findings establish a novel neuronal pathway linking stress-induced proteolysis of EphB2 in the amygdala to anxiety.
Abstract.
Author URL.
Skrzypiec AE, Maiya R, Chen Z, Pawlak R, Strickland S (2009). Plasmin-mediated degradation of laminin gamma-1 is critical for ethanol-induced neurodegeneration.
Biol Psychiatry,
66(8), 785-794.
Abstract:
Plasmin-mediated degradation of laminin gamma-1 is critical for ethanol-induced neurodegeneration.
BACKGROUND: Alcoholism may result in severe neurological deficits and cognitive impairments. Many of the central effects of ethanol (EtOH) can be explained by upregulation of N-methyl-D-aspartate (NMDA) and downregulation of gamma-aminobutyric acid (GABA) a receptors (GABAA) in response to long-term EtOH consumption. Abrupt ethanol withdrawal (EW) may result in neuronal hyperexcitability leading to hallucinations, seizures, neurodegeneration, and sometimes death. METHODS: Using a multidisciplinary approach in wild-type and genetically modified mice, we examined the contribution of the tissue plasminogen activator (tPA), plasminogen, and laminin to EW-induced cell death. RESULTS: Here we show that EW-induced neurodegeneration is mediated by the tPA/plasmin system. During EW, tPA is upregulated in the hippocampus and converts plasminogen to plasmin, which in turn degrades an extracellular matrix component laminin, leading to caspase-3-dependent cell death. Consequently, mice in which the tPA or plasminogen genes have been deleted do not show EW-induced laminin degradation, mitochondrial dysfunction, and neurodegeneration. Finally, we demonstrated that disruption of the hippocampal laminin gamma-1 renders the mice resistant to neurotoxic effects of EW. CONCLUSIONS: Our data identify laminin gamma-1 as a novel target to combat neurodegeneration.
Abstract.
Author URL.
Publications by year
2016
Hall MH, Magalska A, Malinowska M, Ruszczycki B, Czaban I, Patel S, Ambrożek-Latecka M, Zołocińska E, Broszkiewicz H, Parobczak K, et al (2016). Localization and regulation of PML bodies in the adult mouse brain.
Brain Struct Funct,
221(5), 2511-2525.
Abstract:
Localization and regulation of PML bodies in the adult mouse brain.
PML is a tumor suppressor protein involved in the pathogenesis of promyelocytic leukemia. In non-neuronal cells, PML is a principal component of characteristic nuclear bodies. In the brain, PML has been implicated in the control of embryonic neurogenesis, and in certain physiological and pathological phenomena in the adult brain. Yet, the cellular and subcellular localization of the PML protein in the brain, including its presence in the nuclear bodies, has not been investigated comprehensively. Because the formation of PML bodies appears to be a key aspect in the function of the PML protein, we investigated the presence of these structures and their anatomical distribution, throughout the adult mouse brain. We found that PML is broadly expressed across the gray matter, with the highest levels in the cerebral and cerebellar cortices. In the cerebral cortex PML is present exclusively in neurons, in which it forms well-defined nuclear inclusions containing SUMO-1, SUMO 2/3, but not Daxx. At the ultrastructural level, the appearance of neuronal PML bodies differs from the classic one, i.e. the solitary structure with more or less distinctive capsule. Rather, neuronal PML bodies have the form of small PML protein aggregates located in the close vicinity of chromatin threads. The number, size, and signal intensity of neuronal PML bodies are dynamically influenced by immobilization stress and seizures. Our study indicates that PML bodies are broadly involved in activity-dependent nuclear phenomena in adult neurons.
Abstract.
Author URL.
Bradley SJ, Bourgognon J-M, Sanger HE, Verity N, Mogg AJ, White DJ, Butcher AJ, Moreno JA, Molloy C, Macedo-Hatch T, et al (2016). M1 muscarinic allosteric modulators slow prion neurodegeneration and restore memory loss.
Journal of Clinical Investigation,
127(2), 487-499.
Full text.
Harlalka GV, McEntagart ME, Gupta N, Skrzypiec AE, Mucha MW, Chioza BA, Simpson MA, Sreekantan-Nair A, Pereira A, Günther S, et al (2016). Novel Genetic, Clinical, and Pathomechanistic Insights into TFG-Associated Hereditary Spastic Paraplegia.
Hum Mutat,
37(11), 1157-1161.
Abstract:
Novel Genetic, Clinical, and Pathomechanistic Insights into TFG-Associated Hereditary Spastic Paraplegia.
Hereditary spastic paraplegias (HSPs) are genetically and clinically heterogeneous axonopathies primarily affecting upper motor neurons and, in complex forms, additional neurons. Here, we report two families with distinct recessive mutations in TFG, previously suggested to cause HSP based on findings in a single small family with complex HSP. The first carried a homozygous c.317G>A (p.R106H) variant and presented with pure HSP. The second carried the same homozygous c.316C>T (p.R106C) variant previously reported and displayed a similarly complex phenotype including optic atrophy. Haplotyping and bisulfate sequencing revealed evidence for a c.316C>T founder allele, as well as for a c.316_317 mutation hotspot. Expression of mutant TFG proteins in cultured neurons revealed mitochondrial fragmentation, the extent of which correlated with clinical severity. Our findings confirm the causal nature of bi-allelic TFG mutations for HSP, broaden the clinical and mutational spectra, and suggest mitochondrial impairment to represent a pathomechanistic link to other neurodegenerative conditions.
Abstract.
Author URL.
2014
Baple EL, Maroofian R, Chioza BA, Izadi M, Cross HE, Al-Turki S, Barwick K, Skrzypiec A, Pawlak R, Wagner K, et al (2014). Mutations in KPTN cause macrocephaly, neurodevelopmental delay, and seizures.
Am J Hum Genet,
94(1), 87-94.
Abstract:
Mutations in KPTN cause macrocephaly, neurodevelopmental delay, and seizures.
The proper development of neuronal circuits during neuromorphogenesis and neuronal-network formation is critically dependent on a coordinated and intricate series of molecular and cellular cues and responses. Although the cortical actin cytoskeleton is known to play a key role in neuromorphogenesis, relatively little is known about the specific molecules important for this process. Using linkage analysis and whole-exome sequencing on samples from families from the Amish community of Ohio, we have demonstrated that mutations in KPTN, encoding kaptin, cause a syndrome typified by macrocephaly, neurodevelopmental delay, and seizures. Our immunofluorescence analyses in primary neuronal cell cultures showed that endogenous and GFP-tagged kaptin associates with dynamic actin cytoskeletal structures and that this association is lost upon introduction of the identified mutations. Taken together, our studies have identified kaptin alterations responsible for macrocephaly and neurodevelopmental delay and define kaptin as a molecule crucial for normal human neuromorphogenesis.
Abstract.
Author URL.
Tsilibary E, Tzinia A, Radenovic L, Stamenkovic V, Lebitko T, Mucha M, Pawlak R, Frischknecht R, Kaczmarek L (2014). Neural ECM proteases in learning and synaptic plasticity.
Prog Brain Res,
214, 135-157.
Abstract:
Neural ECM proteases in learning and synaptic plasticity.
Recent studies implicate extracellular proteases in synaptic plasticity, learning, and memory. The data are especially strong for such serine proteases as thrombin, tissue plasminogen activator, neurotrypsin, and neuropsin as well as matrix metalloproteinases, MMP-9 in particular. The role of those enzymes in the aforementioned phenomena is supported by the experimental results on the expression patterns (at the gene expression and protein and enzymatic activity levels) and functional studies, including knockout mice, specific inhibitors, etc. Counterintuitively, the studies have shown that the extracellular proteolysis is not responsible mainly for an overall degradation of the extracellular matrix (ECM) and loosening perisynaptic structures, but rather allows for releasing signaling molecules from the ECM, transsynaptic proteins, and latent form of growth factors. Notably, there are also indications implying those enzymes in the major neuropsychiatric disorders, probably by contributing to synaptic aberrations underlying such diseases as schizophrenia, bipolar, autism spectrum disorders, and drug addiction.
Abstract.
Author URL.
2013
Bourgognon J-M, Schiavon E, Salah-Uddin H, Skrzypiec AE, Attwood BK, Shah RS, Patel SG, Mucha M, John Challiss RA, Forsythe ID, et al (2013). Regulation of neuronal plasticity and fear by a dynamic change in PAR1-G protein coupling in the amygdala.
Mol Psychiatry,
18(10), 1136-1145.
Abstract:
Regulation of neuronal plasticity and fear by a dynamic change in PAR1-G protein coupling in the amygdala.
Fear memories are acquired through neuronal plasticity, an orchestrated sequence of events regulated at circuit and cellular levels. The conventional model of fear acquisition assumes unimodal (for example, excitatory or inhibitory) roles of modulatory receptors in controlling neuronal activity and learning. Contrary to this view, we show that protease-activated receptor-1 (PAR1) promotes contrasting neuronal responses depending on the emotional status of an animal by a dynamic shift between distinct G protein-coupling partners. In the basolateral amygdala of fear-naive mice PAR1 couples to Gαq/11 and Gαo proteins, while after fear conditioning coupling to Gαo increases. Concurrently, stimulation of PAR1 before conditioning enhanced, but afterwards it inhibited firing of basal amygdala neurons. An initial impairment of the long-term potentiation (LTP) in PAR1-deficient mice was transformed into an increase in LTP and enhancement of fear after conditioning. These effects correlated with more frequent 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid (AMPA) receptor-mediated miniature post synaptic events and increased neuronal excitability. Our findings point to experience-specific shifts in PAR1-G protein coupling in the amygdala as a novel mechanism regulating neuronal excitability and fear.
Abstract.
Author URL.
Skrzypiec AE, Shah RS, Schiavon E, Baker E, Skene N, Pawlak R, Mucha M (2013). Stress-induced lipocalin-2 controls dendritic spine formation and neuronal activity in the amygdala.
PLoS One,
8(4).
Abstract:
Stress-induced lipocalin-2 controls dendritic spine formation and neuronal activity in the amygdala.
Behavioural adaptation to psychological stress is dependent on neuronal plasticity and dysfunction at this cellular level may underlie the pathogenesis of affective disorders such as depression and post-traumatic stress disorder. Taking advantage of genome-wide microarray assay, we performed detailed studies of stress-affected transcripts in the amygdala - an area which forms part of the innate fear circuit in mammals. Having previously demonstrated the role of lipocalin-2 (Lcn-2) in promoting stress-induced changes in dendritic spine morphology/function and neuronal excitability in the mouse hippocampus, we show here that the Lcn-2 gene is one of the most highly upregulated transcripts detected by microarray analysis in the amygdala after acute restraint-induced psychological stress. This is associated with increased Lcn-2 protein synthesis, which is found on immunohistochemistry to be predominantly localised to neurons. Stress-naïve Lcn-2(-/-) mice show a higher spine density in the basolateral amygdala and a 2-fold higher rate of neuronal firing rate compared to wild-type mice. Unlike their wild-type counterparts, Lcn-2(-/-) mice did not show an increase in dendritic spine density in response to stress but did show a distinct pattern of spine morphology. Thus, amygdala-specific neuronal responses to Lcn-2 may represent a mechanism for behavioural adaptation to psychological stress.
Abstract.
Author URL.
Full text.
2012
Attwood BK, Patel S, Pawlak R (2012). Ephs and ephrins: emerging therapeutic targets in neuropathology.
Int J Biochem Cell Biol,
44(4), 578-581.
Abstract:
Ephs and ephrins: emerging therapeutic targets in neuropathology.
Eph receptors have been the subject of intense research since their discovery. Their widespread pattern of expression, involvement in a variety of important cellular phenomena and unique mode of action have stimulated interest in their role in health and disease across biological and medical domains. However, the function of Ephs in nervous system development and plasticity remains the best characterised. Recent advances suggest that Ephs play an important role in the development of brain pathologies. This review focuses on their basic structure and function and discusses the latest research on their role in neurological diseases.
Abstract.
Author URL.
McGeachie AB, Skrzypiec AE, Cingolani LA, Letellier M, Pawlak R, Goda Y (2012). β3 integrin is dispensable for conditioned fear and hebbian forms of plasticity in the hippocampus.
Eur J Neurosci,
36(4), 2461-2469.
Abstract:
β3 integrin is dispensable for conditioned fear and hebbian forms of plasticity in the hippocampus.
Integrins play key roles in the developing and mature nervous system, from promoting neuronal process outgrowth to facilitating synaptic plasticity. Recently, in hippocampal pyramidal neurons, β3 integrin (ITGβ3) was shown to stabilise synaptic AMPA receptors (AMPARs) and to be required for homeostatic scaling of AMPARs elicited by chronic activity suppression. To probe the physiological function for ITGβ3-dependent processes in the brain, we examined whether the loss of ITGβ3 affected fear-related behaviours in mice. ITGβ3-knockout (KO) mice showed normal conditioned fear responses that were similar to those of control wild-type mice. However, anxiety-like behaviour appeared substantially compromised and could be reversed to control levels by lentivirus-mediated re-expression of ITGβ3 bilaterally in the ventral hippocampus. In hippocampal slices, the loss of ITGβ3 activity did not compromise hebbian forms of plasticity--neither acute pharmacological disruption of ITGβ3 ligand interactions nor genetic deletion of ITGβ3 altered long-term potentiation (LTP) or long-term depression (LTD). Moreover, we did not detect any changes in short-term synaptic plasticity upon loss of ITGβ3 activity. In contrast, acutely disrupting ITGβ1-ligand interactions or genetic deletion of ITGβ1 selectively interfered with LTP stabilisation whereas LTD remained unaltered. These findings indicate a lack of requirement for ITGβ3 in the two robust forms of hippocampal long-term synaptic plasticity, LTP and LTD, and suggest differential roles for ITGβ1 and ITGβ3 in supporting hippocampal circuit functions.
Abstract.
Author URL.
2011
Mucha M, Skrzypiec AE, Schiavon E, Attwood BK, Kucerova E, Pawlak R (2011). Lipocalin-2 controls neuronal excitability and anxiety by regulating dendritic spine formation and maturation.
Proc Natl Acad Sci U S A,
108(45), 18436-18441.
Abstract:
Lipocalin-2 controls neuronal excitability and anxiety by regulating dendritic spine formation and maturation.
Psychological stress causes adaptive changes in the nervous system directed toward maintaining homoeostasis. These biochemical and structural mechanisms regulate animal behavior, and their malfunction may result in various forms of affective disorders. Here we found that the lipocalin-2 (Lcn2) gene, encoding a secreted protein of unknown neuronal function, was up-regulated in mouse hippocampus following psychological stress. Addition of lipocalin-2 to cultured hippocampal neurons reduced dendritic spine actin's mobility, caused retraction of mushroom spines, and inhibited spine maturation. These effects were further enhanced by inactivating iron-binding residues of Lcn-2, suggesting that they were facilitated by the iron-free form of Lcn-2. Concurrently, disruption of the Lcn2 gene in mice promoted stress-induced increase in spine density and caused an increase in the proportion of mushroom spines. The above changes correlated with higher excitability of CA1 principal neurons and with elevated stress-induced anxiety in Lcn-2(-/-) mice. Our study demonstrates that lipocalin-2 promotes stress-induced changes in spine morphology and function to regulate neuronal excitability and anxiety.
Abstract.
Author URL.
Attwood BK, Bourgognon J-M, Patel S, Mucha M, Schiavon E, Skrzypiec AE, Young KW, Shiosaka S, Korostynski M, Piechota M, et al (2011). Neuropsin cleaves EphB2 in the amygdala to control anxiety.
Nature,
473(7347), 372-375.
Abstract:
Neuropsin cleaves EphB2 in the amygdala to control anxiety.
A minority of individuals experiencing traumatic events develop anxiety disorders. The reason for the lack of correspondence between the prevalence of exposure to psychological trauma and the development of anxiety is unknown. Extracellular proteolysis contributes to fear-associated responses by facilitating neuronal plasticity at the neuron-matrix interface. Here we show in mice that the serine protease neuropsin is critical for stress-related plasticity in the amygdala by regulating the dynamics of the EphB2-NMDA-receptor interaction, the expression of Fkbp5 and anxiety-like behaviour. Stress results in neuropsin-dependent cleavage of EphB2 in the amygdala causing dissociation of EphB2 from the NR1 subunit of the NMDA receptor and promoting membrane turnover of EphB2 receptors. Dynamic EphB2-NR1 interaction enhances NMDA receptor current, induces Fkbp5 gene expression and enhances behavioural signatures of anxiety. On stress, neuropsin-deficient mice do not show EphB2 cleavage and its dissociation from NR1 resulting in a static EphB2-NR1 interaction, attenuated induction of the Fkbp5 gene and low anxiety. The behavioural response to stress can be restored by intra-amygdala injection of neuropsin into neuropsin-deficient mice and disrupted by the injection of either anti-EphB2 antibodies or silencing the Fkbp5 gene in the amygdala of wild-type mice. Our findings establish a novel neuronal pathway linking stress-induced proteolysis of EphB2 in the amygdala to anxiety.
Abstract.
Author URL.
2010
Poulin B, Butcher A, McWilliams P, Bourgognon J-M, Pawlak R, Kong KC, Bottrill A, Mistry S, Wess J, Rosethorne EM, et al (2010). The M3-muscarinic receptor regulates learning and memory in a receptor phosphorylation/arrestin-dependent manner.
Proc Natl Acad Sci U S A,
107(20), 9440-9445.
Abstract:
The M3-muscarinic receptor regulates learning and memory in a receptor phosphorylation/arrestin-dependent manner.
Degeneration of the cholinergic system is considered to be the underlying pathology that results in the cognitive deficit in Alzheimer's disease. This pathology is thought to be linked to a loss of signaling through the cholinergic M(1)-muscarinic receptor subtype. However, recent studies have cast doubt on whether this is the primary receptor mediating cholinergic-hippocampal learning and memory. The current study offers an alternative mechanism involving the M(3)-muscarinic receptor that is expressed in numerous brain regions including the hippocampus. We demonstrate here that M(3)-muscarinic receptor knockout mice show a deficit in fear conditioning learning and memory. The mechanism used by the M(3)-muscarinic receptor in this process involves receptor phosphorylation because a knockin mouse strain expressing a phosphorylation-deficient receptor mutant also shows a deficit in fear conditioning. Consistent with a role for receptor phosphorylation, we demonstrate that the M(3)-muscarinic receptor is phosphorylated in the hippocampus following agonist treatment and following fear conditioning training. Importantly, the phosphorylation-deficient M(3)-muscarinic receptor was coupled normally to G(q/11)-signaling but was uncoupled from phosphorylation-dependent processes such as receptor internalization and arrestin recruitment. It can, therefore, be concluded that M(3)-muscarinic receptor-dependent learning and memory depends, at least in part, on receptor phosphorylation/arrestin signaling. This study opens the potential for biased M(3)-muscarinic receptor ligands that direct phosphorylation/arrestin-dependent (non-G protein) signaling as being beneficial in cognitive disorders.
Abstract.
Author URL.
2009
Skrzypiec AE, Maiya R, Chen Z, Pawlak R, Strickland S (2009). Plasmin-mediated degradation of laminin gamma-1 is critical for ethanol-induced neurodegeneration.
Biol Psychiatry,
66(8), 785-794.
Abstract:
Plasmin-mediated degradation of laminin gamma-1 is critical for ethanol-induced neurodegeneration.
BACKGROUND: Alcoholism may result in severe neurological deficits and cognitive impairments. Many of the central effects of ethanol (EtOH) can be explained by upregulation of N-methyl-D-aspartate (NMDA) and downregulation of gamma-aminobutyric acid (GABA) a receptors (GABAA) in response to long-term EtOH consumption. Abrupt ethanol withdrawal (EW) may result in neuronal hyperexcitability leading to hallucinations, seizures, neurodegeneration, and sometimes death. METHODS: Using a multidisciplinary approach in wild-type and genetically modified mice, we examined the contribution of the tissue plasminogen activator (tPA), plasminogen, and laminin to EW-induced cell death. RESULTS: Here we show that EW-induced neurodegeneration is mediated by the tPA/plasmin system. During EW, tPA is upregulated in the hippocampus and converts plasminogen to plasmin, which in turn degrades an extracellular matrix component laminin, leading to caspase-3-dependent cell death. Consequently, mice in which the tPA or plasminogen genes have been deleted do not show EW-induced laminin degradation, mitochondrial dysfunction, and neurodegeneration. Finally, we demonstrated that disruption of the hippocampal laminin gamma-1 renders the mice resistant to neurotoxic effects of EW. CONCLUSIONS: Our data identify laminin gamma-1 as a novel target to combat neurodegeneration.
Abstract.
Author URL.
2008
Skrzypiec AE, Buczko W, Pawlak R (2008). Tissue plasminogen activator in the amygdala: a new role for an old protease.
J Physiol Pharmacol,
59 Suppl 8, 135-146.
Abstract:
Tissue plasminogen activator in the amygdala: a new role for an old protease.
Evidence has accumulated that point to the tissue plasminogen activator (tPA), a serine protease historically associated with blood physiology, as an important regulator of the central nervous system functioning. tPA is highly expressed in the limbic system where it regulates neuronal viability and experience-induced plasticity. In the amygdala tPA is a critical mediator of stress-induced structural and functional rearrangements that ultimately shape up behavioral responses to stressful stimuli. The importance of tPA in the limbic system was confirmed using tPA-deficient mice; these animals do not show biochemical, structural and behavioral signatures normally associated with stress. tPA-mediated facilitation of experience-induced plasticity in the limbic system is mediated by a complex mechanism that may involve direct or indirect interactions of tPA with NMDA receptor, its binding to the LRP receptor or activation of brain-derived growth factor.
Abstract.
Author URL.
2005
Pawlak R, Melchor JP, Matys T, Skrzypiec AE, Strickland S (2005). Ethanol-withdrawal seizures are controlled by tissue plasminogen activator via modulation of NR2B-containing NMDA receptors.
Proc Natl Acad Sci U S A,
102(2), 443-448.
Abstract:
Ethanol-withdrawal seizures are controlled by tissue plasminogen activator via modulation of NR2B-containing NMDA receptors.
Chronic ethanol abuse causes up-regulation of NMDA receptors, which underlies seizures and brain damage upon ethanol withdrawal (EW). Here we show that tissue-plasminogen activator (tPA), a protease implicated in neuronal plasticity and seizures, is induced in the limbic system by chronic ethanol consumption, temporally coinciding with up-regulation of NMDA receptors. tPA interacts with NR2B-containing NMDA receptors and is required for up-regulation of the NR2B subunit in response to ethanol. As a consequence, tPA-deficient mice have reduced NR2B, extracellular signal-regulated kinase 1/2 phosphorylation, and seizures after EW. tPA-mediated facilitation of EW seizures is abolished by NR2B-specific NMDA antagonist ifenprodil. These results indicate that tPA mediates the development of physical dependence on ethanol by regulating NR2B-containing NMDA receptors.
Abstract.
Author URL.
Pawlak R, Rao BSS, Melchor JP, Chattarji S, McEwen B, Strickland S (2005). Tissue plasminogen activator and plasminogen mediate stress-induced decline of neuronal and cognitive functions in the mouse hippocampus.
Proc Natl Acad Sci U S A,
102(50), 18201-18206.
Abstract:
Tissue plasminogen activator and plasminogen mediate stress-induced decline of neuronal and cognitive functions in the mouse hippocampus.
Repeated stress can impair function in the hippocampus, a brain structure essential for learning and memory. Although behavioral evidence suggests that severe stress triggers cognitive impairment, as seen in major depression or posttraumatic stress disorder, little is known about the molecular mediators of these functional deficits in the hippocampus. We report here both pre- and postsynaptic effects of chronic stress, manifested as a reduction in the number of NMDA receptors, dendritic spines, and expression of growth-associated protein-43 in the cornu ammonis 1 region. Strikingly, the stress-induced decrease in NMDA receptors coincides spatially with sites of plasminogen activation, thereby predicting a role for tissue plasminogen activator (tPA) in this form of stress-induced plasticity. Consistent with this possibility, tPA-/- and plasminogen-/- mice are protected from stress-induced decrease in NMDA receptors and reduction in dendritic spines. At the behavioral level, these synaptic and molecular signatures of stress-induced plasticity are accompanied by impaired acquisition, but not retrieval, of hippocampal-dependent spatial learning, a deficit that is not exhibited by the tPA-/- and plasminogen-/- mice. These findings establish the tPA/plasmin system as an important mediator of the debilitating effects of prolonged stress on hippocampal function at multiple levels of neural organization.
Abstract.
Author URL.
