%0 Generic
%A Munoz Perez-Vico, Elena
%C Heidelberg
%D 2024
%F heidok:33451
%K IPSC, BDNF, Neurone
%R 10.11588/heidok.00033451
%T Implications of the Val66Met polymorphism of the BDNF gene  on neuronal morphology and function  using human iPSC-derived neuronal cultures
%U https://archiv.ub.uni-heidelberg.de/volltextserver/33451/
%X Psychiatric disorders such as schizophrenia or major depression are often associated with  specific congenital genetic variants. One of these variants, which has been associated with  that kind of disorder, is the human-specific single nucleotide polymorphism (SNP, rs6265) in  the brain-derived neurotrophic factor (BDNF) gene. About 30 to 60% of the worldwide  population is either homo- or heterozygous for this SNP which is located at codon 66 in the  pro-domain of the protein (Val66Met). It results in a substitution of valine (Val) to methionine  (Met) that impairs the intracellular trafficking as well as the activity-dependent release of the  protein. BDNF, a member of the neurotrophin family, is known to be important in brain  development being involved in neuronal survival, neurite outgrowth and synaptic plasticity.  The aim of this thesis was to investigate the effects of the Val66Met polymorphism on BDNF  trafficking, neuronal morphology and function on an endogenous expression level in humaninduced  pluripotent stem cell (iPSC)-derived neuronal cultures generated from healthy donors  homozygous for either the BDNFVal or BDNFMet variant. To account for the given genetic  heterogeneity of humans, I additionally generated isogenic cell lines using CRISPR/Cas9 gene  editing. Analysis of BDNF localization revealed a decreased number of BDNF+ vesicles on  neurites of BDNFMet/Met neurons compared to BDNFVal/Val neurons. Interestingly, the BDNF  signal was accumulated at the soma of BDNFMet/Met neurons, indicating impaired trafficking of  BDNFMet. Furthermore, a significant reduction in neurite length and complexity in neurons  derived from BDNFMet/Met carriers at early developmental stages was observed. This was  persistent up to later stages of development and could be rescued by external application of  recombinant BDNF. The morphological alterations were accompanied by a reduced synaptic  density in BDNFMet/Met neurons analyzed by immunocytochemistry. These results were  confirmed by functional characterization including calcium imaging and electrophysiological  measurements that showed an altered synaptic function in neurons carrying BDNFMet/Met.  Taken together, my data provide first experimental evidence identifying morphological and  neurophysiological differences in human neurons carrying the BDNF Val66Met polymorphism.  My work demonstrates that human iPSC-derived cortical neurons can be used as a cellular  model to recapitulate previous results gained with animal studies, but also to highlight humanspecific  aspects, which might help to strengthen our understanding of BDNF signaling.