Electrophysiological and Behavioral Phenotypic Characterization of a Transgenic Mouse Model Associated with Syntaxin Binding protein-1 (STXBP1) Developmental and Epileptic Encephalopathy (DEE)
Abstract number :
1.112
Submission category :
2. Translational Research / 2D. Models
Year :
2023
Submission ID :
627
Source :
www.aesnet.org
Presentation date :
12/2/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: NATALIA RODRIGUEZ, PhD – UCB PHARMA
STEFANIE DEDEURWAERDERE, PhD – UCB PHARMA; ANA RITA GOMES, PhD – UCB PHARMA; GEORGES MAIRET COELLO, PhD – UCB PHARMA; BRITTANY VALLETTE, PhD – UCB PHARMA; CHRISTIAN WOLFF, PhD – UCB PHARMA; JEROME CLASADONTE, PhD – UCB PHARMA; yANA VAN DEN HERREWEGEN, PhD – UCB PHARMA; MARCELLA WIDYA, PhD – UCB PHARMA
Rationale:
STXBP1/Munc18-1 (Syntaxin binding protein-1) is an essential protein for presynaptic vesicle exocytosis and neurotransmitter release. Mutations in STXBP1 gene cause early infantile developmental and epileptic encephalopathy (DEE) characterized by infantile epilepsy, developmental delay, intellectual disability, and can include autistic features. Approximately, 80% of mutations are de novo (nonsense, frameshift, missense) leading to a non-functional protein affecting neuronal function. Patients diagnosed with STXBP1-happloinsufiency are reported to develop seizures early in life and not all patients may be controlled by currently available anti-seizure medications. There is no approved therapy addressing the underlying disease mechanism of STXBP1 haploinsufficiency and consequently, experimental models of STXBP1 DEE are needed to explore novel treatments.
Methods:
STXBP1 heterozygous Knock-out (KO) mice have been received under license from the University of Amsterdam. The heterozygous mice (Stxbp1+/-) were generated by deletion of Stxbp1 exon 2 via LoxP/Cre recombination. One to seven month-old male heterozygous STXBP1 KO mice and their Wild-type littermates were used in this study. To assess electrophysiological features in this model, we established a group housing video-EEG wireless telemetry platform that provides continuous recording of video-EEG 24 hours/day. A large battery of traditional neurobehavioral tests was performed to evaluate any potential deficits in gross locomotor activity, motor coordination, muscle tone, muscle strength or cognitive performances. STXBP1 expression levels (Western Blot, qPCR, LCMS) were also evaluated from brain homogenatesacross different brain structures. IHC analysis was performed with a selected antibody that demonstrated selectivity in full STXBP1 (KO) tissues.
Results:
LCMS, qPCR, and Western Blot analysis confirmed a reduction of 40-50% of STXBP1 expression levels in brain tissues from heterozygous STXBP1 KO mice. EEG analysis showed that 90% of STXBP1 KO mice present frequent spike wave discharges (SWD) associated with behavioral arrest (absence seizures). We confirmed that the disease phenotype in STXBP1 KO mice is also characterized by lower body weight, motor dysfunction (hindlimb clasping, decrease muscular strength and locomotion) and cognitive deficits (fear conditioning) compared to their WT littermates.
Conclusions:
Seizures, impaired motor and cognitive aspects and brain hyperexcitability observed in humans are all recapitulated in this STXBP1 KO mouse model. Therefore, this transgenic mouse model is a valid model with reliable readouts to evaluate the efficacy and safety of therapeutic interventions targeting STXBP1-encephalopathy.
Funding: UCB PHARMA
Translational Research