fi=3112 Neurotieteet|sv=3112 Neurovetenskaper|en=3112 Neurosciences|
https://www.doria.fi:443/handle/10024/99055
2024-03-28T21:27:47Zc-Jun N-terminal Kinase (JNK) Regulation of Neuroplastic Changes in Brain Associated with Anxiety- and Depressive-like Behavior
https://www.doria.fi:443/handle/10024/168671
c-Jun N-terminal Kinase (JNK) Regulation of Neuroplastic Changes in Brain Associated with Anxiety- and Depressive-like Behavior
Marchisella, Francesca
Anxiety disorders and clinical depression are leading causes of disability worldwide and affect more than 300 million people of all ages, more prominently women (World Health Organization, 2017). Comorbid depression and anxiety disorders appear in up to 75% of patients, and to further complicate the picture, higher severity and chronicity of illness, reduced quality of life, treatment resistance and poor therapeutic effects are expected when comorbidity of anxiety with depression is diagnosed.
Current therapies stimulate neuroplastic changes in the brain, as a basis for their therapeutic action. In particular, it has been shown that several classes of antidepressants stimulate adult neurogenesis in the hippocampal formation, which is one brain region mostly affected by these two conditions. Nevertheless, current pharmacotherapy conveys a number of drawbacks, including delayed onset of clinical effects and debilitating side effects. Such inefficiency is most likely due to a lack of knowledge of the neuroanatomical and physiological changes occurring during the disease state. Thereby, unravelling the etiology and the pathophysiological mechanisms leading to the aberrant cerebral activity caused by the illnesses might ultimately overcome the downsides of current therapies.
Most recently, the Mitogen Activated Protein kinases (MAPs) have been linked to the development of mood disorders. In particular, the c-Jun N-terminal kinase (JNK) subfamily of MAPKs are activated by different external stressors, such as DNA damage, oxidative stress, cytoskeletal changes, infection or inflammation, and the JNK signaling has been found to be fundamental in brain developmental processes. Moreover, JNK activity modulates brain structures and neuronal morphology. Thus, generation of JNK inhibitors has been progressing as a new attractive avenue for more targeted therapies with less adverse side effects.
The work presented in this thesis tackles the role of JNK signaling in regulation of adult hippocampal neurogenesis and in the control of anxiety-like and depressivelike behavior in mice. By using Jnk1 knockout mice and pharmacological inhibition of JNK pathway, the kinase activity was found linked to adult neurogenesis and emotional behavior in mice. More specifically, Jnk1-/- mice exhibited low anxiety-like and depressive-like phenotype in a battery of behavioral tests. Remarkably, genetic and pharmacological inhibition of JNK heightened proliferation, maturation and survival of the newly born neurons of the hippocampus and facilitated dendrite arborization of newborn neurons, suggesting promotion of integration of the adult born cells into the pre-existing circuitry of the hippocampus. Specific retroviral targeting of JNK in the adult born granule cells of the hippocampus produced low anxiety-like phenotype after four weeks of viral expression and decreased depressivelike phenotype eight-week post-injection. The last part of this thesis aimed to investigate synaptic changes of the adult born granule cells of the hippocampus upon JNK kinase inhibition. Using a calcium indicator downstream of JNK inhibition, we recorded the activity of newly born neurons in awake mice. Our preliminary data indicate that JNK inhibition appears to increase adult born granule cells synaptic activity at four weeks of age in mice undergoing social interaction, and at six weeks of age in response to open field and enriched environment exposure. Altogether, the data presented in this thesis provide evidence on JNK modulation of the neurogenic niche of the hippocampus and of the dentate gyrus synaptic activity. Furthermore, these findings highlight the JNK pathway as a putative novel drug target against anxiety and mood disorders.
2019-05-09T05:49:32ZNovel tools to investigate and control JNK function in models of anxiety and depression
https://www.doria.fi:443/handle/10024/167176
Novel tools to investigate and control JNK function in models of anxiety and depression
Hollós, Patrik
Arbetet som presenteras i den här doktorsavhandlingen behandlar stressaktiverat proteinkinas JNKs funktion i modeller för ångeststörning och depression. Dessa sjukdomar utgör en stor börda för både samhälle och ekonomi. Nuvarande terapi för de här komplexa sjukdomarna är otillräckliga eftersom de tillgängliga läkemedlen riktar sig mot likartade biologiska mekanismer. Den här avhandlingen pekar på JNK-signalering som ett potentiellt mål för utveckling av nya antidepressiva läkemedel. Genom att utnyttja ljusaktiverade genetiska verktyg visades JNK vara en effektor för aktin-dynamik i dendrittaggar; strukturer som är viktiga för nervcellens synaptiska aktivitet. Genom att modulera JNK-aktiviteten i dendrittaggar kunde de negativa effekterna av stresshormonet kortikosteron på synapserna förhindras. Avhandlingsarbetet demonstrerar också att inhibering av JNK i bara några hundra av hippocampus nyfödda celler är tillräckligt för att minska depressivt beteende hos möss, vilket identifierar JNK som en molekylär drivare av aversivt beteende. Slutligen visade fotometrisk studie av nervcellsaktivitet att JNK i nyfödda celler i hippocampus kan påverka nervcellaktiviteten i hippocampus CA3-område i korrelation med förändringar i ångestrelaterat beteende hos möss. En ökad förståelse av de förändringar i nervnätverk som kontrolleras av JNK kan öppna nya möjligheter att behandla affektiva störningar.
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Väitöskirjassa esitetty työ tutkii stressi-aktivoidun proteiinikiinaasi JNK:n toimintaa ahdistuneisuus- ja masennusmalleissa. Nämä sairaudet ovat huomattava rasitus yhteiskunnalle ja taloudelle. Terapiavaste näissä monimuotoisissa taudeissa on usein riittämätön, sillä kaikki nykyiset lääkkeet vaikuttavat samankaltaisten biologisten mekanismien kautta. Tässä työssä osoitetaan, että JNK-signaalikaskadi voisi olla uusien antidepressiivisten lääkeaineiden kehityskohde. Valoresponsiivisia geneettisiä työkaluja käyttäen, huomattiin JNK:n toimivan aktiinidynamiikan efektorina dendriittien okasissa, jotka ovat synaptisessa toiminnassa välttämättömiä solujen alaosastoja. Muokkaamalla näiden alaosastojen JNK-aktiivisuutta pystymme estämään stressihormoni kortikosteronin aiheuttamat synapsituhot. Lisäksi, JNK:n estäminen vain muutamassa sadassa vastasyntyneessä hippokampuksen soluissa lieventää masennuksenkaltaista käyttäytymistä hiirillä, mikä osoittaa JNK:n olevan aversiivisen käyttäytymisen molekulaarinen ajuri. Lopuksi, fotometristä menetelmää käyttäen, tutkimustyö osoittaa, että hippokampuksen vastasyntyneissä soluissa oleva JNK pystyy muokkaamaan hiirten ahdistuneisuuskäyttäytymiseen korreloivaa hermoaktiivisuutta hippokampuksen CA3-alueella. JNK:n säätelyn alaisten hermoverkkojen parempi ymmärtäminen saattaa avata uusia mahdollisuuksia mielialahäiriöiden hoitoon.
2019-01-30T12:44:15ZJNK regulation of neurogenesis, neuroplasticity and anxiety-related behaviors in mice
https://www.doria.fi:443/handle/10024/120737
JNK regulation of neurogenesis, neuroplasticity and anxiety-related behaviors in mice
Mohammad, Hasan
I vår moderna värld har förekomsten av ångeststörningar drastiskt ökat, vilket
påverkar välfärden i våra samhällen. Eftersom de molekylära mekanismerna
bakom ångest är relativt okända, är möjligheterna till behandling av
ångeststörningar begränsade. I och med utvecklingen av genetiska manipuleringmetoder
och avbildningstekniker har strukturella förändringar associerade
med ångeststörningar kunnat konstateras. Neuroanatomiska studier
har påvisat störningar i dendritarkitektur, dendrittaggar och i neurogenesen
hos vuxna individer. Särskilt neurogenesen i hippocampus anses viktig i
detta sammanhang. Neurogenes i hippocampus har föreslagits spela en viktig
roll i ångeststörningarnas patofysiologi och för hur vissa antidepressiva läkemedel
förmedlar sin effekt.
Under senare år har MAP-kinaser (MAPK) föreslagits vara involverade både i
uppkomsten av affektiva störningar och i neurogenes i hippocampus. JNK är
en grupp kinaser inom MAPK-familjen som aktiveras av olika externa stressfaktorer.
I normala celler är aktiviteten hos JNK låg. Cell-stress ökar aktiviteten
hos JNK vilket leder till bl.a. apoptos. JNK kinaser anses vara potentiella
terapeutiska mål för behandling av neurodegenerativa sjukdomar men deras
potential som mål för behandling av affektiva sjukdomar har tillsvidare inte
utretts.
Den här avhandlingen behandlar betydelsen av JNK för ångestrelaterat beteende
hos möss. Med hjälp av Jnk1-knockout möss och farmakologisk inhibering
av JNK-signalering, demonstreras att JNK reglerar neurogenes i
hippocampus, vilket i sin tur ligger bakom mössens ångestrelaterade beteende.
Jnk1-knockout möss var mindre ängsliga och uppvisade ökad neurogenes
i hippcampus jämfört med kontrollmöss. Inhibering av JNK-signalering
i hjärnan hos möss gjorde dem också mindre ängsliga och ökade neurogenesen
i hippocampus på samma sätt som vissa antidepressiva läkemedel. Inhibering
av JNK-aktivitet ledde inte bara till ökad neurogenes i hippocampus,
utan främjade också mognandet av nybildade nervceller hos vuxna möss.
Resultaten visar också att dendritarkitekturen och fördelningen av dendrittaggar
hos CA3 neuroner i hippocampus är förändrad hos Jnk1-knockout
möss. Genom screening av substratmolekyler för JNK hittades två JNKeffektormolekyler,
MARCKSL1 (ett aktin-associerat protein) och MAP2 (ett
mikrotubulus-associerat protein), som reglerade neuronernas sttruktur. Det
här tyder på att JNK-signalering kan kontrollera ångeststörningsrelaterade
förändringar hor dendriter och dendrittaggar.
Sammanfattningsvis ger resultaten som presenteras i avhandlingen en ökad
insikt i molekylära mekanismer som kan leda till ångeststörningsrelaterade
förändringar i neurogenes och dendritstruktur. Därtill föreslås att JNKsignalbanan
har potential som terapeutiskt mål för behandling av ångeststörningar.
2016-03-14T09:58:10ZJNK regulates dendrite and spine architecture in the central nervous system influencing spatial learning and motor tasks
https://www.doria.fi:443/handle/10024/103099
JNK regulates dendrite and spine architecture in the central nervous system influencing spatial learning and motor tasks
Komulainen, Emilia
JNK1 is a MAP-kinase that has proven a significant player in the central nervous system. It regulates brain development and the maintenance of dendrites and axons. Several novel phosphorylation targets of JNK1 were identified in a screen performed in the Coffey lab. These proteins were mainly involved in the regulation of neuronal cytoskeleton, influencing the dynamics and stability of microtubules and actin. These structural proteins form the dynamic backbone for the elaborate architecture of the dendritic tree of a neuron. The initiation and branching of the dendrites requires a dynamic interplay between the cytoskeletal building blocks. Both microtubules and actin are decorated by associated proteins which regulate their dynamics.
The dendrite-specific, high molecular weight microtubule associated protein 2 (MAP2) is an abundant protein in the brain, the binding of which stabilizes microtubules and influences their bundling. Its expression in non-neuronal cells induces the formation of neurite-like processes from the cell body, and its function is highly regulated by phosphorylation. JNK1 was shown to phosphorylate the proline-rich domain of MAP2 in vivo in a previous study performed in the group. Here we verify three threonine residues (T1619, T1622 and T1625) as JNK1 targets, the phosphorylation of which increases the binding of MAP2 to microtubules. This binding stabilizes the microtubules and increases process formation in non-neuronal cells. Phosphorylation-site mutants were engineered in the lab. The non-phosphorylatable mutant of MAP2 (MAP2- T1619A, T1622A, T1625A) in these residues fails to bind microtubules, while the pseudo-phosphorylated form, MAP2- T1619D, T1622D, Thr1625D, efficiently binds and induces process formation even without the presence of active JNK1.
Ectopic expression of the MAP2- T1619D, T1622D, Thr1625D in vivo in mouse brain led to a striking increase in the branching of cortical layer 2/3 (L2/3) pyramidal neurons, compared to MAP2-WT. The dendritic complexity defines the receptive field of a neuron and dictates the output to the postsynaptic cells. Previous studies in the group indicated altered dendrite architecture of the pyramidal neurons in the Jnk1-/- mouse motor cortex. Here, we used Lucifer Yellow loading and Sholl analysis of neurons in order to study the dendritic branching in more detail. We report a striking, opposing effect in the absence of Jnk1 in the cortical layers 2/3 and 5 of the primary motor cortex. The basal dendrites of pyramidal neurons close to the pial surface at L2/3 show a reduced complexity. In contrast, the L5 neurons, which receive massive input from the L2/3 neurons, show greatly increased branching.
Another novel substrate identified for JNK1 was MARCKSL1, a protein that regulates actin dynamics. It is highly expressed in neurons, but also in various cancer tissues. Three phosphorylation target residues for JNK1 were identified, and it was demonstrated that their phosphorylation reduces actin turnover and retards migration of these cells. Actin is the main cytoskeletal component in dendritic spines, the site of most excitatory synapses in pyramidal neurons. The density and gross morphology of the Lucifer Yellow filled dendrites were characterized and we show reduced density and altered morphology of spines in the motor cortex and in the hippocampal area CA3. The dynamic dendritic spines are widely considered to function as the cellular correlate during learning. We used a Morris water maze to test spatial memory. Here, the wild-type mice outperformed the knock-out mice during the acquisition phase of the experiment indicating impaired special memory.
The L5 pyramidal neurons of the motor cortex project to the spinal cord and regulate the movement of distinct muscle groups. Thus the altered dendrite morphology in the motor cortex was expected to have an effect on the input-output balance in the signaling from the cortex to the lower motor circuits. A battery of behavioral tests were conducted for the wild-type and Jnk1-/- mice, and the knock-outs performed poorly compared to wild-type mice in tests assessing balance and fine motor movements. This study expands our knowledge of JNK1 as an important regulator of the dendritic fields of neurons and their manifestations in behavior.
2015-01-07T08:43:17Z