SHORT syndrome due to a novel de novo mutation in PRKCE (Protein Kinase Cɛ) impairing TORC2-dependent AKT activation

Alcantara, Diana, Elmslie, Frances, Tetreault, Martine, Bareke, Eric, Hartley, Taila, Care4Rare Consortium, , Majewski, Jacek, Boycott, Kym, Innes, A Micheil, Dyment, David A and O'Driscoll, Mark (2017) SHORT syndrome due to a novel de novo mutation in PRKCE (Protein Kinase Cɛ) impairing TORC2-dependent AKT activation. Human Molecular Genetics, 26 (19). pp. 3713-3721. ISSN 1460-2083

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Abstract

SHORT syndrome is a rare, recognizable syndrome resulting from heterozygous mutations in PIK3R1 encoding a regulatory subunit of phosphoinositide-3-kinase (PI3K). The condition is characterized by short stature, intrauterine growth restriction, lipoatrophy and a facial gestalt involving a triangular face, deep set eyes, low hanging columella and small chin. PIK3R1 mutations in SHORT syndrome result in reduced signaling through the PI3K-AKT-mTOR pathway. We performed whole exome sequencing for an individual with clinical features of SHORT syndrome but negative for PIK3R1 mutation and her parents. A rare de novo variant in PRKCE was identified. The gene encodes PKCε and, as such, the AKT-mTOR pathway function was assessed using phospho-specific antibodies with patient lymphoblasts and following ectopic expression of the mutant in HEK293 cells. Kinase analysis showed that the variant resulted in a partial loss-of-function. Whilst interaction with PDK1 and the mTORC2 complex component SIN1 was preserved in the mutant PKCε, it bound to SIN1 with a higher affinity than wild-type PKCε and the dynamics of mTORC2-dependent priming of mutant PKCε was altered. Further, mutant PKCε caused impaired mTORC2-dependent pAKT-S473 following rapamycin treatment. Reduced pFOXO1-S256 and pS6-S240/244 levels were also observed in the patient LCLs. To date, mutations in PIK3R1 causing impaired PI3K-dependent AKT activation are the only known cause of SHORT syndrome. We identify a SHORT syndrome child with a novel partial loss-of-function defect in PKCε. This variant causes impaired AKT activation via compromised mTORC2 complex function.

Item Type: Article
Schools and Departments: School of Life Sciences > Sussex Centre for Genome Damage and Stability
Research Centres and Groups: Genome Damage and Stability Centre
Subjects: Q Science > QM Human anatomy
Q Science > QP Physiology
R Medicine > RB Pathology
Depositing User: Mark O'Driscoll
Date Deposited: 22 Sep 2017 09:23
Last Modified: 22 Sep 2017 10:25
URI: http://sro.sussex.ac.uk/id/eprint/70304

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