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. 2018 Feb 15;27(4):589-600.
doi: 10.1093/hmg/ddx426.

FRMPD4 mutations cause X-linked intellectual disability and disrupt dendritic spine morphogenesis

Juliette Piard  1 , Jia-Hua Hu  2   3 , Philippe M Campeau  4 , Sylwia Rzonca  5 , Hilde Van Esch  6 , Elizabeth Vincent  2 , Mei Han  2 , Elsa Rossignol  7 , Jennifer Castaneda  5 , Jamel Chelly  8 , Cindy Skinner  9 , Vera M Kalscheuer  10 , Ruihua Wang  2 , Emmanuelle Lemyre  4 , Joanna Kosinska  5 , Piotr Stawinski  5 , Jerzy Bal  5 , Dax A Hoffman  3 , Charles E Schwartz  9 , Lionel Van Maldergem  1   11 , Tao Wang  2 , Paul F Worley  2
Affiliations

FRMPD4 mutations cause X-linked intellectual disability and disrupt dendritic spine morphogenesis

Juliette Piard et al. Hum Mol Genet. .

Abstract

FRMPD4 (FERM and PDZ Domain Containing 4) is a neural scaffolding protein that interacts with PSD-95 to positively regulate dendritic spine morphogenesis, and with mGluR1/5 and Homer to regulate mGluR1/5 signaling. We report the genetic and functional characterization of 4 FRMPD4 deleterious mutations that cause a new X-linked intellectual disability (ID) syndrome. These mutations were found to be associated with ID in ten affected male patients from four unrelated families, following an apparent X-linked mode of inheritance. Mutations include deletion of an entire coding exon, a nonsense mutation, a frame-shift mutation resulting in premature termination of translation, and a missense mutation involving a highly conserved amino acid residue neighboring FRMPD4-FERM domain. Clinical features of these patients consisted of moderate to severe ID, language delay and seizures alongside with behavioral and/or psychiatric disturbances. In-depth functional studies showed that a frame-shift mutation, FRMPD4p.Cys618ValfsX8, results in a disruption of FRMPD4 binding with PSD-95 and HOMER1, and a failure to increase spine density in transfected hippocampal neurons. Behavioral studies of frmpd4-KO mice identified hippocampus-dependent spatial learning and memory deficits in Morris Water Maze test. These findings point to an important role of FRMPD4 in normal cognitive development and function in humans and mice, and support the hypothesis that FRMPD4 mutations cause ID by disrupting dendritic spine morphogenesis in glutamatergic neurons.

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Figures

Figure 1.
Figure 1.
Pedigree, photographs, and brain MRIs of Affected Males with ID and FRMPD4p.Cys618ValfsX8 in an XLID Family. (A) Pedigree shows 5 affected males from a multigenerational family. Filled square: affected males; circle with a center dot, carrier females; unfilled square: unaffected males; unfilled circle: unaffected females. Symbols with a line crossed: deceased. (B) Note absence of distinct dysmorphic features except for bifid tip of the nose in P1 (II: 1). (C) Note absence of distinct dysmorphic features and a white matter hyper-signal in the left occipital horn on brain MRI (axial T2) in P2 (III: 1). (D) Note absence of distinct dysmorphic features and a left temporal arachnoid cyst (axial T1) in P5 (III: 8).
Figure 2.
Figure 2.
Additional FRMPD4 Mutations in Affected Individuals with XLID. (A) Established domain structure of FRMPD4 and nature and locations of FRMPD4 mutations found in patients with ID. WW (domain with two conserved Trp residues): PDZ (PSD-95/Dlg/ZO-1): RA; FERM (four-point-one, ezrin, radixin, and moesin). (B) Genomic structure of FRMPD4 and genomic location of family 3 microdeletion. (C) Pedigrees and segregation analysis of FRMPD4 mutations identified in families 2, 3 and 4. Filled square, affected males; open square, unaffected males; circle with a center dot, unaffected carrier female; filled circle with a center dot, mildly disabled carrier female. (D) Brain MRI scans of P6 (at 12 years) and P7 (at 17 years) from Family 2. Note diffuse atrophy of white matter principally in the periventricular region, delayed myelination with periventricular white matter atrophy of P6 (top panel, axial T1), and compare to cortical atrophy and enlarged ventricles of P7 (bottom panel, axial T2). (E) Photographs of family 3 probands and their mildly disabled sister. (F) Proband of family 4 at different ages. Note frontal upsweep, trigonocephaly and broad nasal bridge.
Figure 3.
Figure 3.
Binding of FRMPD4p.Cys618ValfsX8 with known interacting proteins. (A) Domain structure of human FRMPD4 and its mutant protein. (B) Various FRMPD4 and Homer1c constructs were transfected into HEK293T cells. Anti-myc antibody immunoprecipitated FRMPD4-WT and FRMPD4p.Cys618ValfsX8. Homer1C was co-immunoprecipitated by FRMPD4-WT, but not FRMPD4p.Cys618ValfsX8. (C) Various FRMPD4 and PSD-95 constructs were transfected into HEK293T cells. Anti-myc antibody immunoprecipitated FRMPD4-WT and FRMPD4p.Cys618ValfsX8. PSD-95 was co-immunoprecipitated by FRMPD4-WT while this binding was significantly reduced between FRMPD4p.Cys618ValfsX8 and PSD-95.
Figure 4.
Figure 4.
FRMPD4p.Cys618ValfsX8 losses the ability to increase spine density. (A) Cultured hippocampal neurons were transfected with myc–FRMPD4 (WT or FRMPD4p.Cys618ValfsX8) plus EGFP or EGFP alone (control) (DIV 14) and visualized by immunofluorescence staining for EGFP. Images were analyzed by Neurolucida 360 to show different spine shapes. Scale bar, 10 μm. (B) FRMPD4-WT overexpression increased spine density but FRMPD4p.Cys618ValfsX8 did not. Mean ± 95% confidence interval (n = 19 neurons for EGFP, 18 for WT, and 20 for mutant, *P < 0.05, t-test). (C–F) Spines were classified into four categories. FRMPD4-WT overexpression increased mushroom spines but not thin spines, stubby spines and filopodia spines. FRMPD4p.Cys618ValfsX8 did not increase mushroom or other spine categories. Mean ± 95% confidence interval (n = 19 neurons for EGFP, 18 for WT, and 20 for mutant, *P < 0.05, t-test).
Figure 5.
Figure 5.
Frmpd4-KO mice show normal spatial working memory but a defective spatial reference memory. The Y-maze tests for spatial working memory include Spontaneous Alternation and Blocked Arm tests. (A) Spontaneous Alternation: the test mouse was placed at the end of one arm and remained in the maze for 5 min. The total number of correct alternations divided by the number of total possible alternations was recorded and analyzed. (B) Blocked Arm test: one of the three arms was blocked, the test mouse was allowed to explore the 2 unblocked arms for 5 min followed by rest for 10 min. The test mouse was returned to the maze with all 3 arms open and allowed to explore for another 5 min. Data was analyzed for time spent in the arm blocked during the second trial (novel arm) and presented as mean ± SEM. t-test was used to compare data between frmpd4-KO mice (n = 15) and WT littermates (n = 15). *P < 0.05 was considered statistically significant. Note that no significant difference was identified between WT and frmpd4-KO in these tests suggesting a normal working memory function. Morris water maze is used to test hippocampus dependent spatial reference memory. (C) Training trials: mice were subjected to four, 1-min swim trials each day in the water maze to locate a hidden platform using multiple spatial signs. The time to reach the platform is an average of 4 trials for each mouse, n = 15 mice per group. Note that frmpd4-KO mice showed slow progression in reducing time needed to locate the platform compared with WT. (D) Probe trial: after the training trial, mice were subjected to one 3-min trial of free swimming in maze without the platform. Time spent probing the quadrant where the platform was located during training trial and total number of crosses to the platform region were automatically tracked and compared between frmpd4-KO and WT control mice. Note the reduced number of crosses to the platform site in the frmpd4-KO. MEAN ± SEM was presented. t-test was used to compare data at each test point between WT and frmpd4-KO mice. *p< 0.05 was considered statistically significant. Note frmpd4-KO mice (n = 15) showed significantly reduced number of crosses to the platform site compared with WT littermates (n = 15) suggesting a deficit in the spatial reference memory function.
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References

    1. Deciphering Developmental Disorders Study. (2015) Large-scale discovery of novel genetic causes of developmental disorders. Nature, 519, 223–228. - PMC - PubMed
    1. Maulik P., Mascarenhas M., Mathers C., Dua T., Saxena S. (2011) Prevalence of intellectual disability: a meta-analysis of population-based studies. Res. Dev. Disabil., 32, 419–436. - PubMed
    1. Stevenson R. (2000) Splitting and lumping in the nosology of XLMR. Am. J. Med. Genet., 97, 174–182. - PubMed
    1. Ropers H., Hamel B. (2005) X-linked mental retardation. Nat. Rev. Genet., 6, 46–57. - PubMed
    1. Chelly J., Mandel J. (2001) Monogenic causes of X-linked mental retardation. Nat. Rev. Genet., 2, 669–680. - PubMed

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