Cornelia de Lange Syndrome (CdLS) is a rare genetic disorder affecting almost any organ including the central nervous system, inducing a variable neurodevelopmental delay. CdLS malformations derive from mutations in cohesin complex genes (protein complex involved in the cohesion control of sister chromatids) and deregulation of developmental pathways, inclusive of the canonical WNT pathway, which results less active. In order to ameliorate the phenotype, I have explored possible ameliorative effects of the canonical WNT pathway chemical activation using lithium in two different models: human induced pluripotent stem cells (hiPSCs) and Drosophila melanogaster. For mimicking cohesins haploinsufficiency, hiPSCs differentiated in neural precursor cells (hNPC) were treated with a specific HDAC8 inhibitor, protein known to be implicated in CdLS pathogenesis. Upon treatment with lithium chloride, cells showed improved differentiation capabilities through the neuronal lineage. Drosophila melanogaster adults carrying a loss-of-function allele in a cohesins gene and reared on food supplemented with lithium as activator of canonical WNT pathway, showed a significant rescue in mushroom bodies morphology, a central nervous system structure important for the olfactory learning and memory. This PhD project’s results further support the hypothesis that disruption in canonical WNT pathway, caused by cohesins mutations, plays a central role in CdLS etiopathogenesis. This theory is corroborated by the consistent phenotype rescue by lithium administration in experimental models, paving the way for new possible and urgently needed therapeutic strategies.
La sindrome di Cornelia de Lange (CdLS) è una rara malattia genetica che colpisce ogni distretto del corpo, compreso il sistema nervoso centrale, causando un ritardo variabile del neurosviluppo. Le malformazioni causate da questa sindrome derivano da mutazioni a carico di geni del complesso delle coesine (complesso proteico coinvolto nel controllo della coesione dei cromatidi fratelli) e da un’alterata regolazione di pathway molecolari durante lo sviluppo, tra cui il pathway canonico di WNT, che risulta essere meno attivo. Al fine di osservare un miglioramento del fenotipo, ho indagato i potenziali effetti positivi dell’utilizzo di cloruro di litio come attivatore del pathway canonico di WNT, avvalendomi di due modelli differenti: cellule staminali pluripotenti indotte di origine umana (hiPSCs) e Drosophila melanogaster. Per simulare un’aploinsufficienza delle coesine, le hiPSCs differenziate in precursori neurali (hNPC), sono state trattate con uno specifico inibitore della proteina HDAC8, nota per essere implicata nella patogenesi della CdLS. Dopo essere state trattate con cloruro di litio, queste cellule hanno mostrato una migliorata capacità di differenziamento attraverso il lineage neuronale. Esemplari adulti di Drosophila melanogaster portatori di un allele loss-of-function a carico di un gene delle coesine, dopo essere stati allevati su cibo supplementato con litio come attivatore del pathway canonico di WNT, hanno mostrato un recupero statisticamente significativo della morfologia dei mushroom bodies, una struttura del sistema nervoso centrale importante per l'apprendimento olfattivo e la memoria. I risultati derivanti da questo progetto di dottorato supportano ulteriormente l’ipotesi che una perturbazione del pathway canonico di WNT, causato da mutazioni a carico delle coesine, giochi un ruolo centrale nell’eziopatogenesi della CdLS. Questa teoria è corroborata dal recupero consistente del fenotipo nei modelli sperimentali grazie alla somministrazione di cloruro di litio e apre la strada a possibili strategie terapeutiche, fortemente necessarie per la CdLS.
IN VITRO AND IN VIVO MODELLING OF CORNELIA DE LANGE SYNDROME CAUSATIVE MUTATIONS: WNT ACTIVATION AS A POSSIBLE THERAPEUTIC APPROACH
GRAZIOLI, PAOLO
2021
Abstract
Cornelia de Lange Syndrome (CdLS) is a rare genetic disorder affecting almost any organ including the central nervous system, inducing a variable neurodevelopmental delay. CdLS malformations derive from mutations in cohesin complex genes (protein complex involved in the cohesion control of sister chromatids) and deregulation of developmental pathways, inclusive of the canonical WNT pathway, which results less active. In order to ameliorate the phenotype, I have explored possible ameliorative effects of the canonical WNT pathway chemical activation using lithium in two different models: human induced pluripotent stem cells (hiPSCs) and Drosophila melanogaster. For mimicking cohesins haploinsufficiency, hiPSCs differentiated in neural precursor cells (hNPC) were treated with a specific HDAC8 inhibitor, protein known to be implicated in CdLS pathogenesis. Upon treatment with lithium chloride, cells showed improved differentiation capabilities through the neuronal lineage. Drosophila melanogaster adults carrying a loss-of-function allele in a cohesins gene and reared on food supplemented with lithium as activator of canonical WNT pathway, showed a significant rescue in mushroom bodies morphology, a central nervous system structure important for the olfactory learning and memory. This PhD project’s results further support the hypothesis that disruption in canonical WNT pathway, caused by cohesins mutations, plays a central role in CdLS etiopathogenesis. This theory is corroborated by the consistent phenotype rescue by lithium administration in experimental models, paving the way for new possible and urgently needed therapeutic strategies.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14242/74561
URN:NBN:IT:UNIMI-74561