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Funkcjonalne konsekwencje utraty aktywności genu PTEN w hipokampie dorosłych myszy : praca doktorska
Creator: Contributor:Konopka, Witold (1975- ) : Supervisor ; Kiryk-Jaśkiewicz, Anna : Auxiliary supervisor
Publisher:Instytut Biologii Doświadczalnej im. Marcelego Nenckiego PAN
Place of publishing: Date issued/created: Description:151 pages : illustrations ; 30 cm ; Bibliography ; Summary in English
Degree name: Degree discipline : Degree grantor:Nencki Institute of Experimental Biology PAS ; degree obtained: 2026
Type of object: Subject and Keywords:Excitatory neurons ; Hippocampus ; Learning ; Memory ; PTEN knockout ; Social interactions
Abstract:
PTEN (phospatase and tensin homolog deleted on chromosome 10) belongs to a group of tumor suppressor genes whose function is to maintain stable cell growth and integrity by inhibiting the cascade of intracellular signals that activate the expression of genes responsible for growth, survival and proliferation. The PTEN gene encodes a phosphatase enzyme with dual activity, targeting both proteins and lipids. The key action of PTEN phosphatase is its opposing activity to PI3K kinase, an interaction that maintains activation of this pathway at appropriate levels. Early reports on PTEN's function indicated its important role in regulating the cell's metabolic pathways and in inhibiting tumorigenesis. In the context of PTEN's function in neurons, its association with Autism Spectrum Disorder (ASD), a neurodevelopmental disorder, has been demonstrated. In order to precisely study the function of Pten in neurons, a number of animal models were generated with conditional inactivation of the Pten gene during embryonic development. Structural changes of neurons characterized by hypertrophy of perikaryon and nerve cell protrusions were observed, which affected functional abnormalities in synaptic transmission and excitability, contributing to impaired memory, impaired social interaction, and finally ataxia and the development of epilepsy in transgenic animals. In these models, it has been possible to obtain a phenotypic picture similar to the features observed in ASD. Despite many years of research into the function of the Pten gene in neurons, still little is known about its importance in fully differentiated neurons in adults. This has largely been due to the limited availability of genetic engineering tools to perform appropriate manipulations. The main objective of this dissertation was to verify the research hypothesis of whether increased stimulation of the PI3K-AKT pathway due to loss of functional Pten protein in differentiated excitatory neurons in the hippocampal area affects the cognitive abilities of the animals studied. In addition, the effect of the introduced mutation on the animals' locomotor activity, anxiety, social memory, social behavior and communication abilities was examined. The aforementioned was aimed at determining whether the variation present could be indicative of an autistic phenotype, and which traits depend on the absence of the Pten gene during development, and which are unique to differentiated neurons. The first stage of the study used a mouse model of Pten-CaMKIIα-CreERT2 with conditional tamoxifen-inducible deletion of the Pten gene in differentiated forebrain excitatory neurons in adult animals (Pten-iCKO). It was observed that the mutants showed enhanced spatial memory in tests performed in IntelliCage cages. However, increased mortality was observed in these animals between 7 and 13 weeks after mutation activation. For this reason, the next step used a Pten fl/fl animal model in which the Pten gene mutation, induced with AAV-CaMKIIα-Cre vectors, was restricted to hippocampal neurons (Pten-AAV-KO). Between 7 and 15 weeks after AAV vector injection, learning ability and spatial memory tests were performed in IntelliCage and conventional behavioral tests with analysis of ultrasound vocalizations at specific time points. The efficacy of the mutation was confirmed after about 7 weeks by reduced levels of Pten protein in the hippocampus and concomitant increased activity of mTOR kinase (as an effector to deregulate the PI3K- Pten interaction). During this time, too, Pten-AAV-KO mice performed better in learning and memory tests compared to the control group. In addition, Pten-AAV-KO mutants were characterized by increased locomotor excitability in IntelliCage and the open field test, reduced anxiety levels (sex-dependent) in the elevated plus maze, and increased exploratory activity during social interactions (...)
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Digitizing institution:Nencki Institute of Experimental Biology of the Polish Academy of Sciences
Original in:Library of the Nencki Institute of Experimental Biology PAS
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