A Critical Role for Protein Tyrosine Phosphatase Nonreceptor Type 5 in Determining Individual Susceptibility to Develop Stress-Related Cognitive and Morphological Changes. or how I learned to quit caring and love the Dendritic Spine Density of the Dorsal Hippocampus CA 1 Pyramidal Neuron and OLM voodoo. Where we will be going today Low PTPN5 expression Increased ERK 1/2 activation Increase in Ca V 1.2 expression and (phosphorylation of ) K V 4.2 channel recovery delay from inactivation Glutamate (and Bay K8644) excitotoxicity Influx of Ca 2+ into cell cellular degradation BAM! susceptibility to stress/physical degradation of nervous system! Where we are looking Dorsal Hippocampus Memory consolidation Spatial navigation What we are interested in CA 1 area Stuff this area does? Bonus: This exact picture showed up in another advanced seminar presentation. First to tell me which one gets a shiny Zachary Taylor Do you know? Because Andy doesnt Protein tyrosine phosphatase nonreceptor type 5 PTPN5 functions in regulating the duration of extracellular signal-regulated kinase (ERK) activation and downstream transcriptional responses after NMDA receptor stimulation, NMDA receptor endocytosis by amyloid, and AMPA receptor endocytosis after metabotropic glutamate receptor stimulation, suggesting that PTPN5 signaling may function as a tonic suppressor of synaptic strengthening. What is ERK? Erk! In this case not a silly sound ERK 1/2 Extracellular signal-related kinase. Controls Ion channels Neurtotransmitter receptors Protein kinases Transcription factors And more. Like lions, tigers, and bear. Erk? What you need to know about ERK1/2 Responsible for a cascade of events, that eventually results in an increased expression of Ca v 1.2 channels and recovery delay of K V 4.2 channels from inactivation. Glutamate Massively important (excitatory) neurotransmitter Its just about in every nerve cell, and is incorporated into the proteins of just about every cell in the body Two main receptors. NMDA AMPA NMDA receptor action Shamelessly stoleer borrowed from Cliffs webpage. Action Potential If more is needed on the action potential put it here (LTP LDP?) Excitotoxicity Cell death by Ca 2+ overload In our case caused by over-active NMDAr Methods Rats Male adult Sprague Dawley rats. Rats were tested during light phase (b/n 10a 3p) Stress Protocol Tail shock while held immobile in a plexiglass tube. 1 mA for 1 s, sec apart Why?! Object location memory test (OLM) Open-field box (40x40x40 cm) 10min exploration/acclimation Test 5min exploration Score time spent investigating objects Discrimination Index (Cognitive Performance) [time on novel / (time on + time on )] x 100% 3hrs, and 1wk post stress Methods Other Stress measurements: Sucrose preference Seek less sweet, SAD Open Field tests Like more hiding, SAD Resident-intruder test Less aggressive to intruder, not SAD? Forced-swimming test Less swim, SAD Plasma corticosterone recording High corticosterone, SAD (stressed really) Do you expect me to talk? No Mr. Bond. I expect you to have a marked increase in corticosterone levels! Corticosterone = Stress Methods Lentivirus injection Knockouts and overexpression! Recombinant Lentivirus Shut stuff down shRNA (small hairpin RNA) Leads to RNA interference. This results in perfect cleaving of mRNA or simply prevents mRNA translation. Overexpression Overexpression of PTPN5 ( specifically STEP 46 which is six-fold more active than STEP 61 ) THE PAPER PROPER Results/Things Done Individual differences in susceptibility to stress-related cognitive and morphological changes PTPN5 determines individual susceptibility to develop stress-related cognitive and morphological changes PTPN5 loss of function increases susceptibility to develop stress-related cognitive and morphological changes, and vice-versa. PTPN5 gain of function decreases susceptibility to develop stress-related cognitive and morphological changes. PTPN5 loss of function increases excitatory overload. Individual differences in susceptibility to stress-related cognitive and morphological changes Rats respond differently to stress! Although initial response, at least as quantified here, was similar. Long term responses differed. Based on these responses rats could be grouped into susceptible and unsusceptible categories. OLM scores (AKA Voodoo) Dendritic spine density in pyramidal CA1 neurons Other measurements of stress Graphs: Figure 1 A: shows how the rats are distributed that werent stressed, before and after(3hr after and 1wk) stress event. B: dividng rats into susceptible and non-susceptible groups, based off of OLM score. C: Break down of Susceptible vs. Unsusceptible individuals post shock D: Chart showing dendritic spine density in hippocampal CA1 pyramidal cells E: spine density in response to acute stress. 1wk after exposure. F: Pretty picture of Dendritic Spines G: Correlation b/n spine density and OLM performance 1wk post stress Graphs: Figure 2 A: % Susceptible. NS 0% Post-S 1 wk 20% Post-S 2 wk 24% B: % Susceptible. NS 0% Post-S 1 wk 24% Post-S 2 wk 22% C: Sucrose Pref. in susceptible vs unseuceptible rats at 1 and 2 weeks post stress. D: Forced Swim results all rats, post shock (+control) E: Corticosteroid levels all rats, post swim test (+control) PTPN5 determines individual susceptibility to develop stress-related cognitive and morphological changes Susceptible rats expressed lower PTPN5 levels compared to nonstressed and unsusceptible rats. Susceptible rats had lower PTPN5 mRNA levels in the DH PTPN5 levels were significantly correlated with OLM performance. Likewise dendritic spine density was significantly correlated with OLM performance. Figure 3 Fig A: PTPN5 protein expression in hippocampal CA1 region Fig B: PTPN5 activity in CA1 tissue Fig: C 11 brain enriched protein tyrosine-phosphatases. Note difference in PTPN5 in susceptible and unsusceptible rats. Fig. D: Correlation analysis of discrimination index and PTPN5 expression. Fig. E: Correlation analysis of dendritic spine density and PTPN5 expression. PTPN5 loss of function increases susceptibility to develop stress-related cognitive and morphological changes. Knockout PTPN5 expression. Lentivirus coexpressing EGFP (electric green florescent protein) and anti-PTPN5 shRNA or control sh-DsRed. Injected into CA1 region 1wk recover Test OLM Dendritic Spine Density Figure 4 Fig. C: PTPN5 Silencing confirmed (sh- DsRed) Fig. D: charts showing susceptibility and performance in OLM. 1wk post stress 1 week or immediately post stress Fig. E: Charts and graphs showing susceptibility based on spine density. Fig. F: Control injection vs PTPN5 silenced individuals LTP induction (Pre and immediate post shock) Help? Still a little fuzzy on what this tells us exactly. Fig. G: Control Injection vs PTPN5 silenced individuals in LTD induction (Pre and immediate post shock) 24h post stress Fig. H: ERK 1/2 phosphorylation in PTPN5 silenced and control rats Fig. I: 24hr post shock LTP induction in nave, control injection, and PTPN5 silenced individuals. Fig. J: 24hr post shock LDP induction in nave, control injection, and PTPN5 silenced individuals. PTPN5 gain of function decreases susceptibility to develop stress-related cognitive and morphological changes Overexpression of a very active PTPN5 variant. Normally STEP 61, researchers injected STEP 46. Sixfold more active. Think SUPER PTPN5 (unless Summers says not to) Due to possibility that PTPN5 overexpression would lead to a decrease in surface expression of NMDA receptors, viral titers were manipulated to yield an approximate 2-3 fold increase in PTPn5 activity. 1hr post stress Fig. C: Confirmation of PTPN5 overexpression Fig. D: control, control injection, and PTPN5 overexpression LTP induction response Fig. E: control, control injection, and PTPN5 overexpression LTD induction. Fig. F: ERK 1/2 phosphorylation in control injection and PTPN5 over expression rats. No Stress, immediate post stress, 1hr post stress, and 24hr post stress. Fig. G: graphs and charts of OLM performance of nave, control injection, and PTPN5 over expression. 1wk post stress. Fig. H: graphs and charts of dendritic spine density in nave, control injection, and PTPN5 over expression rats. 1wk post stress. PTPN5 loss of function increases excitatory overload. Take a look at ERK1/2 dependent signaling PTPN5 silenced rats showed significantly prolonged ERK1/2 activation. Shown by ERK1/2 and K V 4.2 channel phosphorylation at Thr607 compared to controls Phosphorylation = activity suppression Delayed increase in Ca V 1.2 channel expression after stress, which was significantly promoted in PTPN5 silenced rats. Shut er down! Loss of function cont. A closer look at the role of ERK in Ca V 1.2 and K V 4.2 phosphorylation. Administered ERKI (ERK1/2 docking site inhibitor), into DH 24hr post silencing. Resulted in significantly reduced Ca V 1.2 channel expression which prevented stress-related cognitive and morphological changes in PTPN5 silenced rats 1wk post injection. Decreased dendritic spine loss and OLM performance impairment. Suggests that sustained ERK1/2 activation in low PTPN5 expression individuals leads to stress Loss of function cont. Susceptible rats significant increase in Ca V 1.2 channel expression compared to nonstressed and unsusceptible rats 1wk post procedure. Glutamate (fig. 7 d-g) Curious if increased Ca V 1.2 channel expression and K V 4.2 phosphorylation would increase cell vulnerability to Glu. Administered Ca V 1.2 and K V 4.2 agonists (Bay K8644) Brain slices from control injection and silenced individuals. 5d post procedure. PTPN5 individuals showed increased susceptibility to Glu and Bay K8644 toxicity Blocking ERK and Ca V 1.2 in PTPN5 silenced rats significantly reduced Glu. Vulnerability Loss of function (final) Block L type Ca V 1.2 channels after stress to reduce occurrence of stress phenotypes Used nifedipine 48hrs post stress or 5d post stress Resulted in significant reduction in stress phenotype Final experiment, knockout Ca V 1.2 in PTPN5 silenced rats. 24hr post procedure. OLM and Dendritic spine density measured Unsurprisingly, rats expressed extremely low Ca V 1.2 levels. And as a result less stress phenotype. Figure 6 Fig. A: Various expressions based off of PTPN5 knockout vs control infected individuals. Fig. B: various concentrations for control infected rats vs PTPN5 knockout rats. Fig. D: Ca V 1.2 protein expression in PTPN5 silenced individual with control vehicle or ERKI (ERK1/2 docking site inhibitor) Fig. E: Graphs and Charts of OLM criteria in PTPN5 silenced individuals with vehicle or ERKI Fig. F: Graphs and Charts of OLM criteria in PTPN5 silenced indivuals with vehicle or ERKI Figure 7 Fig. A: Ca V 1.2 protein expression levels in control, unsusceptible and susceptible rats. 1 week post stress. Fig. B: Correlation analysis of Ca V 1.2 expression and OLM discrimination index 1wk post stress. Fig. C: Correlation analysis of Ca V 1.2 expression and dendritic spine density. Susceptible Fig. D: comparison of cell death by [glutamate] in PTPN5 silenced and control injection. Fig. E: comparison of [LDH] in PTPN5 silenced and control injection rats. Fig. F: comparison of cell death by [Bay K8644] ] in PTPN5 silenced and control injection rats. Fig. G: comparison of [LDH] ] in PTPN5 silenced and control injection rats. LDH = Lactate Dehydrogenase. Another metric used to measure cell death. Results from tissue breakdown. Bay K8644 = Calcium channel agonist. Fig. I: Charts and graphs of OLM performance 1wk post stress for control, early and late Nifedipine injections Fig. J: Charts and graphs of dendritic spine density 1wk post stress in control and early and late Nifedipine injections. Figure 8 Fig. B: Ca V 1.2 protein expression in DH of PTPN5 silenced individuals with either control injection vs Ca V 1.2 knockout, plus control 1wk post stress. Fig. C: Charts and graphs of OLM index in PTPN5 silenced rats either control, vehicle control, or Ca V 1.2 silenced 1 wk post stressed. Fig. D: Charts and graphs of dendritic spine density in PTPN5 silenced rats either control, vehicle control, or Ca V 1.2 silenced 1 wk post stressed. What happened Low PTPN5 expression Increased ERK1/2 activation increase in Ca V 1.2 expression and K V 4.2 (phosphorylation) channel recovery delay from inactivation Glutamate (and Bay K8644) excitotoxicity cell degradation BAM! susceptibility to stress! Fin