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Homozygous KIAA1033/WASHC4 mutation in siblings with a syndromic phenotype defined by intellectual disability, sensorineural hearing loss, dysmorphisms and muscle fiber vulnerability

ABSTRACT: The Wiskott-Aldrich Syndrome Protein (WASP) family is known for its participation in cytoskeleton reorganization (Marchand et al., 2001 and Jia et al., 2010). In 2007, the human subtelomeric MGC52000 genes were renamed as Wiskott-Aldrich Syndrome Protein and SCAR Homolog (WASH). Human WASH proteins are part of the WASP protein family and colocalize with actin in cells and promote Arp2/3-dependent actin polymerization in vitro (Linardopoulou et al., 2007). WASH multiprotein complex consists of seven subunits: notable to mention Strumpelin and Was Protein Family Homolog (WASH)-interacting protein (SWIP), which is encoded by KIAA1033/WASHC4 gene, FAM21 and Arp2/3. The Arp2/3 dependent actin polymerization from G-actin to F-actin is an important step in regulation of the cytoskeleton, enabling multiple endosomal transport processes (Kelleher et al., 1995 and Derivery et al., 2010). Linardopoulou and colleagues have also shown in an animal model (Drosophila), that the single WASH ortholog is essential for viability (Linardopoulou et al., 2007), strengthening the concept, that WASHC4 plays a crucial role in muscle cell integrity and function. A link between autosomal recessive intellectual disability (ARID) and mutations in the KIAA1033/WASHC4 gene was first recognized in 2011 by Ropers and colleagues. Very recently, Assoum and colleagues reported three additional patients (from two unrelated families) with syndromic ID. Two of them being sisters (8 and 6 years), both presenting with learning disabilities, macrocephaly, dysmorphic features, skeletal anomalies and subependymal heterotopic nodules due to a compound heterozygous mutation of the KIAA1033/WASHC4 gene (p.[Gln442*] and p.[Asp1048Gly]). In this study, we precisely describe the clinical phenotype of the two siblings and provide additional information (histological and proteomic data) derived from the muscle biopsy of the elder sibling to confirm the pathogenicity of the reported variant and establish the function of WASHC4 as relevant for muscle homeostasis. Which, as far as the authors know, has not yet been described in literature.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Andreas Hentschel

LAB HEAD: Andreas Hentschel

PROVIDER: PXD024222 | Pride | 2021-10-14

REPOSITORIES: Pride

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Project description:The cytoplasmic functions of Wiskott-Aldrich Syndrome family (WASP) proteins are well known and include roles in cytoskeleton reorganization and membrane-cytoskeletal interactions important for membrane/vesicle trafficking, morphogenesis, immune response and signal transduction. Mis-regulation of these proteins is associated with immune deficiency and metastasis. Cytoplasmic WASP proteins act as effectors of Rho family GTPases and polymerize branched actin through the Arp2/3 complex. However, recent evidence has revealed that this classically cytoplasmic protein family also functions in the nucleus. Previously, we identified Drosophila washout (wash) as a new member of the WASP family with essential cytoplasmic roles in early development. Here we show that Wash is also present in the nucleus and plays a key role in nuclear organization via its interaction with Lamin Dm0 at the nuclear envelope. Wash and Lamin Dm0 occupy similar genomic regions that overlap with transcriptionally silent chromatin including constitutive heterochromatin. Strikingly, wash mutant and knockdown nuclei exhibit the same abnormal wrinkled morphology observed in diverse laminopathies, including the Hutchinson-Gilford progeria syndrome, and consistent with disruption of the nuclear organization of several sub-nuclear structures including cajal bodies and the chromocenter in salivary glands. We also found that Wash and Lamin knockdown disrupt chromatin accessibility of repressive compartments in agreement with an observed global redistribution of repressive histone modifications. Functional genetic approaches show wash mutants exhibit similar phenotypes to lamin Dm0 mutants, suggesting they participate in similar regulatory networks. Our results reveal a novel role for Wash in modulating nuclear organization via its interaction with the nuclear envelope protein Lamin Dm0. These findings highlight the functional complexity of WASP family proteins and provide new venues to understand their molecular roles in cell biology and disease. We evaluated the effect of Wash knockdown in S2R+ cells on chromatin accessibility using an M.SssI-based approach.

Project description:The cytoplasmic functions of Wiskott-Aldrich Syndrome family (WASP) proteins are well known and include roles in cytoskeleton reorganization and membrane-cytoskeletal interactions important for membrane/vesicle trafficking, morphogenesis, immune response and signal transduction. Mis-regulation of these proteins is associated with immune deficiency and metastasis. Cytoplasmic WASP proteins act as effectors of Rho family GTPases and polymerize branched actin through the Arp2/3 complex. However, recent evidence has revealed that this classically cytoplasmic protein family also functions in the nucleus. Previously, we identified Drosophila washout (wash) as a new member of the WASP family with essential cytoplasmic roles in early development. Here we show that Wash is also present in the nucleus and plays a key role in nuclear organization via its interaction with Lamin Dm0 at the nuclear envelope. Wash and Lamin Dm0 occupy similar genomic regions that overlap with transcriptionally silent chromatin including constitutive heterochromatin. Strikingly, wash mutant and knockdown nuclei exhibit the same abnormal wrinkled morphology observed in diverse laminopathies, including the Hutchinson-Gilford progeria syndrome, and consistent with disruption of the nuclear organization of several sub-nuclear structures including cajal bodies and the chromocenter in salivary glands. We also found that Wash and Lamin knockdown disrupt chromatin accessibility of repressive compartments in agreement with an observed global redistribution of repressive histone modifications. Functional genetic approaches show wash mutants exhibit similar phenotypes to lamin Dm0 mutants, suggesting they participate in similar regulatory networks. Our results reveal a novel role for Wash in modulating nuclear organization via its interaction with the nuclear envelope protein Lamin Dm0. These findings highlight the functional complexity of WASP family proteins and provide new venues to understand their molecular roles in cell biology and disease. DamID chromatin profiling demostrate that Wash binds similar regions to those bound by Lamin Dm0, in particular transcriptional silent chromatin

Project description:Phagocytosis requires the activation of a plethora of mechanisms that include the activation of the actin cytoskeleton guided by the Arp2/3 complex. These are promoted by activators such as the Wiskott Aldrich Syndrome Protein (WASP) family members. In order to further understand the molecular mechanisms involved in the early events leading the phagocytosis of the pathogenic Mycobacterium tuberculosis, we set out to examine potential roles of miRNAs in phagocytosis using genome-wide expression profiling to identify miRNAs differentially regulated following mycobacterial infection. One of the miRNAs activated upon infection of mouse macrophages with the non-pathogenic Mycobacterium smegmatis, the widely conserved miR-142-3p, was predicted and confirmed to target the Neural-WASP (N-WASP). Upregulating of miR-142-3p in mouse macrophages inversely correlated with levels of N-WASP, upon infection with live pathogenic and non-pathogenic mycobacteria, suggesting an active role of Mycobacterium tuberculosis on the regulation of phagocytosis, at the post-transcriptional level, in host cells. The reduction of N-WASP correlated with a reduced internalization of bacteria per macrophage, independently of the phagocytosis index. Furthermore, the downregulation of WASP levels accompanied those of N-WASP, at early but not at late time points, suggesting a closely regulatory mechanism among both family members, dependent on the time frame of the phagocytosis. Additionally, upregulating of miR-142-3p promoted the change in the protein levels of another predicted and confirmed target, the Cofilin2 protein, in a phagocytosis-independent fashion. Downregulation experiments promoted aberrant morphologic phenotypes in macrophages, similar to observed by others in PBMCs of humans with Wiskott Aldrich Syndrome, suggesting the strong involvement of miR-142-3p on the regulation of the actin machinery in macrophages. Altogether these results show for the first time that miRNAs are involved in the regulation of actin-mediated phagocytosis of pathogenic bacteria and that these are direct targets of Mycobacterium tuberculosis. Expression analysis of mouse macrophage cell line J774A.1 in response to infection with Mycobacterium smegmatis mc2155 EGFP. Three biological replicates each for uninfected and infected samples.

			Action	DRS
	Fibro_Fmal_Wash4c_Report.xlsx	Xlsx
	Lumos09382_FMAL_1.raw	Raw
	Lumos09383_FMAL_2.raw	Raw
	Lumos09384_FMAL_3.raw	Raw
	Lumos09385_FMAL_4.raw	Raw

Dataset Information

Homozygous KIAA1033/WASHC4 mutation in siblings with a syndromic phenotype defined by intellectual disability, sensorineural hearing loss, dysmorphisms and muscle fiber vulnerability

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