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Elife. 2015 Dec 3;4. pii: e12703. doi: 10.7554/eLife.12703.

Mouse models of human PIK3CA-related brain overgrowth have acutely treatable epilepsy.

Author information

1
Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.
2
Department of Cancer Biology, Dana Farber Cancer Institute, Boston, United States.
3
Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, United States.
4
The University of Texas MD Anderson Cancer Center, Houston, United States.

Abstract

Mutations in the catalytic subunit of phosphoinositide 3-kinase (PIK3CA) and other PI3K-AKT pathway components have been associated with cancer and a wide spectrum of brain and body overgrowth. In the brain, the phenotypic spectrum of PIK3CA-related segmental overgrowth includes bilateral dysplastic megalencephaly, hemimegalencephaly and focal cortical dysplasia, the most common cause of intractable pediatric epilepsy. We generated mouse models expressing the most common activating Pik3ca mutations (H1047R and E545K) in developing neural progenitors. These accurately recapitulate all the key human pathological features including brain enlargement, cortical malformation, hydrocephalus and epilepsy, with phenotypic severity dependent on the mutant allele and its time of activation. Underlying mechanisms include increased proliferation, cell size and altered white matter. Notably, we demonstrate that acute 1 hr-suppression of PI3K signaling despite the ongoing presence of dysplasia has dramatic anti-epileptic benefit. Thus PI3K inhibitors offer a promising new avenue for effective anti-epileptic therapy for intractable pediatric epilepsy patients.

KEYWORDS:

BKM120; PI3K; cortical dysplasia; epilepsy; human biology; medicine; megalencephaly; mouse; mouse models; neuroscience

PMID:
26633882
PMCID:
PMC4744197
DOI:
10.7554/eLife.12703
[Indexed for MEDLINE]
Free PMC Article

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