title: A mutation in PAK3 with a dual molecular effect deregulates the RAS/MAPK pathway and drives an X-linked syndromic phenotype.
abstract: Loss-of-function mutations in PAK3 contribute to non-syndromic X-linked intellectual disability (NS-XLID) by affecting dendritic spine density and morphology. Linkage analysis in a three-generation family with affected males showing ID, agenesis of corpus callosum, cerebellar hypoplasia, microcephaly and ichthyosis, revealed a candidate disease locus in Xq21.33q24 encompassing over 280 genes. Subsequent to sequencing all coding exons of the X chromosome, we identified a single novel variant within the linkage region, affecting a conserved codon of PAK3. Biochemical studies showed that, similar to previous NS-XLID-associated lesions, the predicted amino acid substitution (Lys389Asn) abolished the kinase activity of PAK3. In addition, the introduced residue conferred a dominant-negative function to the protein that drives the syndromic phenotype. Using a combination of in vitro and in vivo studies in zebrafish embryos, we show that PAK3(N389) escapes its physiologic degradation and is able to perturb MAPK signaling via an uncontrolled kinase-independent function, which in turn leads to alterations of cerebral and craniofacial structures in vivo. Our data expand the spectrum of phenotypes associated with PAK3 mutations, characterize a novel mechanism resulting in a dual molecular effect of the same mutation with a complex PAK3 functional deregulation and provide evidence for a direct functional impact of aberrant PAK3 function on MAPK signaling.
authors.affiliation: U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC).
authors.forename: Pamela
authors.initials: P
authors.lastname: Magini
authors.affiliation: U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC).
authors.forename: Tommaso
authors.initials: T
authors.lastname: Pippucci
authors.affiliation: Center for Human Disease Modeling, Duke University Medical Center, Durham 27710, USA.
authors.forename: I-Chun
authors.initials: IC
authors.lastname: Tsai
authors.affiliation: Centro Nazionale per le Malattie Rare, Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Roma 00161, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Coppola
authors.affiliation: Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Roma 00161, Italy.
authors.forename: Emilia
authors.initials: E
authors.lastname: Stellacci
authors.affiliation: Laboratorio di Neuropatologia, Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM).
authors.forename: Anna
authors.initials: A
authors.lastname: Bartoletti-Stella
authors.affiliation: U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC).
authors.forename: Daniela
authors.initials: D
authors.lastname: Turchetti
authors.affiliation: U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC).
authors.forename: Claudio
authors.initials: C
authors.lastname: Graziano
authors.affiliation: U.O. Anatomia e Istologia Patologica, Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM).
authors.forename: Giovanna
authors.initials: G
authors.lastname: Cenacchi
authors.affiliation: U.O. Dermatologia, Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES).
authors.forename: Iria
authors.initials: I
authors.lastname: Neri
authors.affiliation: U.O. Neuropsichiatria Infantile, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC) and.
authors.forename: Duccio Maria
authors.initials: DM
authors.lastname: Cordelli
authors.affiliation: U.O. Neuropsichiatria Infantile, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC) and.
authors.forename: Valentina
authors.initials: V
authors.lastname: Marchiani
authors.affiliation: Pediatria d'Urgenza, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), Università di Bologna, Bologna 40138, Italy.
authors.forename: Rosalba
authors.initials: R
authors.lastname: Bergamaschi
authors.affiliation: U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC).
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Gasparre
authors.affiliation: Istituto di Genetica Medica, Università Cattolica del Sacro Cuore, Roma 00168, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Neri
authors.affiliation: S.S. Malattie Rare e Sindromologia, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), Università di Bologna, Policlinico S.Orsola-Malpighi, Bologna 40138, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Mazzanti
authors.affiliation: U.O. Dermatologia, Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES).
authors.forename: Annalisa
authors.initials: A
authors.lastname: Patrizi
authors.affiliation: U.O. Neuropsichiatria Infantile, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC) and.
authors.forename: Emilio
authors.initials: E
authors.lastname: Franzoni
authors.affiliation: U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC).
authors.forename: Giovanni
authors.initials: G
authors.lastname: Romeo
authors.affiliation: IRCCS AOU S. Martino - IST, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Bordo
authors.affiliation: Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Roma 00161, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Tartaglia
authors.affiliation: Center for Human Disease Modeling, Duke University Medical Center, Durham 27710, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Katsanis
authors.affiliation: U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), marco.seri@unibo.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Seri
mesh_terms: D000818:Animals; D005091:Exons / Q000235:genetics; D006801:Humans; D007621:Karyotyping; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D054462:p21-Activated Kinases / Q000235:genetics*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C515911:PAK3 protein, human; D054462:p21-Activated Kinases; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins