@article {919, title = {DAAM2 Variants Cause Nephrotic Syndrome via Actin Dysregulation.}, journal = {Am J Hum Genet}, volume = {107}, year = {2020}, month = {2020 12 03}, pages = {1113-1128}, abstract = {

The discovery of >60 monogenic causes of nephrotic syndrome (NS) has revealed a central role for the actin regulators RhoA/Rac1/Cdc42 and their effectors, including the formin INF2. By whole-exome sequencing (WES), we here discovered bi-allelic variants in the formin DAAM2 in four unrelated families with steroid-resistant NS. We show that DAAM2 localizes to the cytoplasm in podocytes and in kidney sections. Further, the variants impair DAAM2-dependent actin remodeling processes: wild-type DAAM2 cDNA, but not cDNA representing missense variants found in individuals with NS, rescued reduced podocyte migration rate (PMR) and restored reduced filopodia formation in shRNA-induced DAAM2-knockdown podocytes. Filopodia restoration was also induced by the formin-activating molecule IMM-01. DAAM2 also co-localizes and co-immunoprecipitates with INF2, which is intriguing since variants in both formins cause NS. Using in~vitro bulk and TIRF microscopy assays, we find that DAAM2 variants alter actin assembly activities of the formin. In a Xenopus daam2-CRISPR knockout model, we demonstrate actin dysregulation in~vivo and glomerular maldevelopment that is rescued by WT-DAAM2 mRNA. We conclude that DAAM2 variants are a likely cause of monogenic human SRNS due to actin dysregulation in podocytes. Further, we provide evidence that DAAM2-associated SRNS may be amenable to treatment using actin regulating compounds.

}, keywords = {Actins, Alleles, Animals, Animals, Genetically Modified, Cell Movement, Cytoplasm, Formins, Genetic Variation, Humans, Kidney, Kidney Glomerulus, Microfilament Proteins, Mutation, Missense, Nephrotic Syndrome, Podocytes, Pseudopodia, rho GTP-Binding Proteins, RNA, Small Interfering, Whole Exome Sequencing, Xenopus}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2020.11.008}, author = {Schneider, Ronen and Deutsch, Konstantin and Hoeprich, Gregory J and Marquez, Jonathan and Hermle, Tobias and Braun, Daniela A and Seltzsam, Steve and Kitzler, Thomas M and Mao, Youying and Buerger, Florian and Majmundar, Amar J and Onuchic-Whitford, Ana C and Kolvenbach, Caroline M and Schierbaum, Luca and Schneider, Sophia and Halawi, Abdul A and Nakayama, Makiko and Mann, Nina and Connaughton, Dervla M and Kl{\"a}mbt, Verena and Wagner, Matias and Riedhammer, Korbinian M and Renders, Lutz and Katsura, Yoshichika and Thumkeo, Dean and Soliman, Neveen A and Mane, Shrikant and Lifton, Richard P and Shril, Shirlee and Khokha, Mustafa K and Hoefele, Julia and Goode, Bruce L and Hildebrandt, Friedhelm} } @article {818, title = {HEM1 deficiency disrupts mTORC2 and F-actin control in inherited immunodysregulatory disease.}, journal = {Science}, volume = {369}, year = {2020}, month = {2020 07 10}, pages = {202-207}, abstract = {

Immunodeficiency often coincides with hyperactive immune disorders such as autoimmunity, lymphoproliferation, or atopy, but this coincidence is rarely understood on a molecular level. We describe five patients from four families with immunodeficiency coupled with atopy, lymphoproliferation, and cytokine overproduction harboring mutations in , which encodes the hematopoietic-specific HEM1 protein. These mutations cause the loss of the HEM1 protein and the WAVE regulatory complex (WRC) or disrupt binding to the WRC regulator, Arf1, thereby impairing actin polymerization, synapse formation, and immune cell migration. Diminished cortical actin networks caused by WRC loss led to uncontrolled cytokine release and immune hyperresponsiveness. HEM1 loss also blocked mechanistic target of rapamycin complex 2 (mTORC2)-dependent AKT phosphorylation, T cell proliferation, and selected effector functions, leading to immunodeficiency. Thus, the evolutionarily conserved HEM1 protein simultaneously regulates filamentous actin (F-actin) and mTORC2 signaling to achieve equipoise in immune responses.

}, keywords = {Actins, ADP-Ribosylation Factor 1, CD4-Positive T-Lymphocytes, Cell Proliferation, Cytokines, Humans, Immunologic Deficiency Syndromes, Lymphoproliferative Disorders, Mechanistic Target of Rapamycin Complex 2, Membrane Proteins, Pedigree, Phosphorylation, Wiskott-Aldrich Syndrome Protein Family}, issn = {1095-9203}, doi = {10.1126/science.aay5663}, author = {Cook, Sarah A and Comrie, William A and Poli, M Cecilia and Similuk, Morgan and Oler, Andrew J and Faruqi, Aiman J and Kuhns, Douglas B and Yang, Sheng and Vargas-Hernandez, Alexander and Carisey, Alexandre F and Fournier, Benjamin and Anderson, D Eric and Price, Susan and Smelkinson, Margery and Abou Chahla, Wadih and Forbes, Lisa R and Mace, Emily M and Cao, Tram N and Coban-Akdemir, Zeynep H and Jhangiani, Shalini N and Muzny, Donna M and Gibbs, Richard A and Lupski, James R and Orange, Jordan S and Cuvelier, Geoffrey D E and Al Hassani, Moza and Al Kaabi, Nawal and Al Yafei, Zain and Jyonouchi, Soma and Raje, Nikita and Caldwell, Jason W and Huang, Yanping and Burkhardt, Janis K and Latour, Sylvain and Chen, Baoyu and ElGhazali, Gehad and Rao, V Koneti and Chinn, Ivan K and Lenardo, Michael J} } @article {828, title = {Loss of the neural-specific BAF subunit ACTL6B relieves repression of early response genes and causes recessive autism.}, journal = {Proc Natl Acad Sci U S A}, volume = {117}, year = {2020}, month = {2020 05 05}, pages = {10055-10066}, abstract = {

Synaptic activity in neurons leads to the rapid activation of genes involved in mammalian behavior. ATP-dependent chromatin remodelers such as the BAF complex contribute to these responses and are generally thought to activate transcription. However, the mechanisms keeping such "early activation" genes silent have been a mystery. In the course of investigating Mendelian recessive autism, we identified six families with segregating loss-of-function mutations in the neuronal BAF (nBAF) subunit (originally named ). Accordingly, was the most significantly mutated gene in the Simons Recessive Autism Cohort. At least 14 subunits of the nBAF complex are mutated in autism, collectively making it a major contributor to autism spectrum disorder (ASD). Patient mutations destabilized ACTL6B protein in neurons and rerouted dendrites to the wrong glomerulus in the fly olfactory system. Humans and mice lacking showed corpus callosum hypoplasia, indicating a conserved role for in facilitating neural connectivity. knockout mice on two genetic backgrounds exhibited ASD-related behaviors, including social and memory impairments, repetitive behaviors, and hyperactivity. Surprisingly, mutation of relieved repression of early response genes including AP1 transcription factors (, , , and ), increased chromatin accessibility at AP1 binding sites, and transcriptional changes in late response genes associated with early response transcription factor activity. loss is thus an important cause of recessive ASD, with impaired neuron-specific chromatin repression indicated as a potential mechanism.

}, keywords = {Actins, Adenosine Triphosphate, Animals, Autism Spectrum Disorder, Behavior, Animal, Chromatin, Chromatin Assembly and Disassembly, Chromosomal Proteins, Non-Histone, Chromosome Pairing, Corpus Callosum, Dendrites, Disease Models, Animal, DNA-Binding Proteins, Gene Expression Regulation, Hippocampus, Humans, Mice, Mice, Knockout, Mutation, Neurons, Transcription Factors}, issn = {1091-6490}, doi = {10.1073/pnas.1908238117}, author = {Wenderski, Wendy and Wang, Lu and Krokhotin, Andrey and Walsh, Jessica J and Li, Hongjie and Shoji, Hirotaka and Ghosh, Shereen and George, Renee D and Miller, Erik L and Elias, Laura and Gillespie, Mark A and Son, Esther Y and Staahl, Brett T and Baek, Seung Tae and Stanley, Valentina and Moncada, Cynthia and Shipony, Zohar and Linker, Sara B and Marchetto, Maria C N and Gage, Fred H and Chen, Dillon and Sultan, Tipu and Zaki, MAH S and Ranish, Jeffrey A and Miyakawa, Tsuyoshi and Luo, Liqun and Malenka, Robert C and Crabtree, Gerald R and Gleeson, Joseph G} } @article {438, title = {ERCC4 variants identified in a cohort of patients with segmental progeroid syndromes.}, journal = {Hum Mutat}, volume = {39}, year = {2018}, month = {2018 02}, pages = {255-265}, abstract = {

Pathogenic variants in genes, which encode DNA repair and damage response proteins, result in a number of genomic instability syndromes with features of accelerated aging. ERCC4 (XPF) encodes a protein that forms a complex with ERCC1 and is required for the 5{\textquoteright} incision during nucleotide excision repair. ERCC4 is also FANCQ, illustrating a critical role in interstrand crosslink repair. Pathogenic variants in this gene cause xeroderma pigmentosum, XFE progeroid syndrome, Cockayne syndrome (CS), and Fanconi anemia. We performed massive parallel sequencing for 42 unsolved cases submitted to the International Registry of Werner Syndrome. Two cases, each carrying two novel heterozygous ERCC4 variants, were identified. The first case was a compound heterozygote for: c.2395C~>~T (p.Arg799Trp) and c.388+1164_792+795del (p.Gly130Aspfs*18). Further molecular and cellular studies indicated that the ERCC4 variants in this patient are responsible for a phenotype consistent with a variant of CS. The second case was heterozygous for two variants in cis: c.[1488A~>~T; c.2579C~>~A] (p.[Gln496His; Ala860Asp]). While the second case also had several phenotypic features of accelerated aging, we were unable to provide biological evidence supporting the pathogenic roles of the associated ERCC4 variants. Precise genetic causes and disease mechanism of the second case remains to be determined.

}, keywords = {Actins, Aged, Cockayne Syndrome, DNA Repair, DNA-Binding Proteins, Fanconi Anemia, Female, Genetic Predisposition to Disease, Humans, Lamin Type A, Male, Middle Aged, Pedigree, Xeroderma Pigmentosum}, issn = {1098-1004}, doi = {10.1002/humu.23367}, author = {Mori, Takayasu and Yousefzadeh, Matthew J and Faridounnia, Maryam and Chong, Jessica X and Hisama, Fuki M and Hudgins, Louanne and Mercado, Gabriela and Wade, Erin A and Barghouthy, Amira S and Lee, Lin and Martin, George M and Nickerson, Deborah A and Bamshad, Michael J and Niedernhofer, Laura J and Oshima, Junko} } @article {365, title = {Diagnosis of Chronic Intestinal Pseudo-obstruction and Megacystis by Sequencing the ACTG2 Gene.}, journal = {J Pediatr Gastroenterol Nutr}, volume = {65}, year = {2017}, month = {2017 10}, pages = {384-387}, abstract = {

OBJECTIVES: The diagnosis of chronic intestinal pseudo-obstruction has depended on clinical features, manometry, and imaging. This report aimed to determine the efficacy of sequencing the actin γ-2 (ACTG2) gene for diagnosis. In addition, the goal was to determine how often a mutation would be found in our randomly collected cohort of probands and those probands published previously.

METHODS: Whole exome sequencing was performed in 4 probands with chronic intestinal pseudo-obstruction. Subsequently, only the ACTG2 gene was sequenced in another 24 probands (total 28). We analyzed published data of 83 probands and our 28 (total 111) and determined how many had pathogenic variants and the precise genotype.

RESULTS: Whole exome and Sanger sequencing revealed a pathogenic variant in the ACTG2 gene in 4 out of 28 of our probands and in 45 out of 83 published probands (49/111 [44.1\%]). Moreover, a mutational hotspot in the ACTG2 gene was recognized. Genetic heterogeneity is evident.

CONCLUSIONS: Pooled gene sequencing results from 1 individual in each of 111 families enabled a precise diagnosis of an ACTG2 mutation in 49 (44\%). The benefit to patients and families of early confirmation of a motility disorder not only helps avoid unnecessary intervention, but also enables institution of appropriate treatments and avoidance of secondary disorders such as malnutrition and poor growth. Knowledge of a pathogenic variant in a parent, with a 50\% risk of recurrence, provides an opportunity for genetic counseling.

}, keywords = {Actins, Adult, Child, Child, Preschool, Chronic Disease, Duodenum, Female, Fetal Diseases, Genetic Markers, Genetic Testing, Humans, Infant, Infant, Newborn, Intestinal Pseudo-Obstruction, Male, Mutation, Sequence Analysis, DNA, Urinary Bladder, Whole Exome Sequencing}, issn = {1536-4801}, doi = {10.1097/MPG.0000000000001608}, author = {Milunsky, Aubrey and Baldwin, Clinton and Zhang, Xiaoying and Primack, Daniel and Curnow, Adrian and Milunsky, Jeff} } @article {391, title = {Heterozygous variants in ACTL6A, encoding a component of the BAF complex, are associated with intellectual disability.}, journal = {Hum Mutat}, volume = {38}, year = {2017}, month = {2017 10}, pages = {1365-1371}, abstract = {

Pathogenic variants in genes encoding components of the BRG1-associated factor (BAF) chromatin remodeling complex have been associated with intellectual disability syndromes. We identified heterozygous, novel variants in ACTL6A, a gene encoding a component of the BAF complex, in three subjects with varying degrees of intellectual disability. Two subjects have missense variants affecting highly conserved amino acid residues within the actin-like domain. Missense mutations in the homologous region in yeast actin were previously reported to be dominant lethal and were associated with impaired binding of the human ACTL6A to β-actin and BRG1. A third subject has a splicing variant that creates an in-frame deletion. Our findings suggest that the variants identified in our subjects may have a deleterious effect on the function of the protein by disturbing the integrity of the BAF complex. Thus, ACTL6A gene mutation analysis should be considered in patients with intellectual disability, learning disabilities, or developmental language disorder.

}, keywords = {Actins, Adolescent, Child, Chromatin Assembly and Disassembly, Chromosomal Proteins, Non-Histone, DNA Helicases, DNA-Binding Proteins, Exome, Face, Female, Hand Deformities, Congenital, Heterozygote, Humans, Intellectual Disability, Male, Micrognathism, Multiprotein Complexes, Mutation, Missense, Nuclear Proteins, Protein Binding, Transcription Factors}, issn = {1098-1004}, doi = {10.1002/humu.23282}, author = {Marom, Ronit and Jain, Mahim and Burrage, Lindsay C and Song, I-Wen and Graham, Brett H and Brown, Chester W and Stevens, Servi J C and Stegmann, Alexander P A and Gunter, Andrew T and Kaplan, Julie D and Gavrilova, Ralitza H and Shinawi, Marwan and Rosenfeld, Jill A and Bae, Yangjin and Tran, Alyssa A and Chen, Yuqing and Lu, James T and Gibbs, Richard A and Eng, Christine and Yang, Yaping and Rousseau, Justine and de Vries, Bert B A and Campeau, Philippe M and Lee, Brendan} } @article {416, title = {Visceral myopathy: Clinical and molecular survey of a cohort of seven new patients and state of the art of overlapping phenotypes.}, journal = {Am J Med Genet A}, volume = {170}, year = {2016}, month = {2016 11}, pages = {2965-2974}, abstract = {

Visceral motility dysfunction is a key feature of genetic disorders such as megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS, MIM moved from 249210 to 155310), chronic intestinal pseudo-obstruction (CIPO, MIM609629), and multisystemic smooth muscle dysfunction syndrome (MSMDS, MIM613834). The genetic bases of these conditions recently begun to be clarified with the identification of pathogenic variants in ACTG2, ACTA2, and MYH11 in individuals with visceral motility dysfunction. The MMIHS was associated with the heterozygous variant in ACTG2 and homozygous variant in MYH11, while the heterozygous variant in ACTA2 was observed in patients with MSMDS. In this study, we describe the clinical data as well as the molecular investigation of seven individuals with visceral myopathy phenotypes. Five patients presented with MMIHS, including two siblings from consanguineous parents, one had CIPO, and the other had MSMDS. In three individuals with MMIHS and in one with CIPO we identified heterozygous variant in ACTG2, one being a novel variant (c.584C>T-p.Thr195Ile). In the individual with MSMDS we identified a heterozygous variant in ACTA2. We performed the whole-exome sequencing in one sibling with MMIHS and her parents; however, the pathogenic variant responsible for her phenotype could not be identified. These results reinforce the clinical and genetic heterogeneity of the visceral myopathies. Although many cases of MMIHS are associated with ACTG2 variants, we suggest that other genes, besides MYH11, could cause the MMIHS with autosomal recessive pattern. {\textcopyright} 2016 Wiley Periodicals, Inc.

}, keywords = {Abnormalities, Multiple, Actins, Child, Preschool, Colon, Consanguinity, DNA Mutational Analysis, Fatal Outcome, Female, Genetic Association Studies, Humans, Infant, Infant, Newborn, Intestinal Pseudo-Obstruction, Male, Mutation, Phenotype, Polymorphism, Single Nucleotide, Treatment Outcome, Ultrasonography, Prenatal, Urinary Bladder}, issn = {1552-4833}, doi = {10.1002/ajmg.a.37857}, author = {Moreno, Carolina Araujo and Metze, Konradin and Lomazi, Elizete Aparecida and Bertola, D{\'e}bora Romeo and Barbosa, Ricardo Henrique Almeida and Cosentino, Viviana and Sobreira, Nara and Cavalcanti, Denise Pontes} } @article {257, title = {Heterozygous de novo and inherited mutations in the smooth muscle actin (ACTG2) gene underlie megacystis-microcolon-intestinal hypoperistalsis syndrome.}, journal = {PLoS Genet}, volume = {10}, year = {2014}, month = {2014 Mar}, pages = {e1004258}, abstract = {

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a rare disorder of enteric smooth muscle function affecting the intestine and bladder. Patients with this severe phenotype are dependent on total parenteral nutrition and urinary catheterization. The cause of this syndrome has remained a mystery since Berdon{\textquoteright}s initial description in 1976. No genes have been clearly linked to MMIHS. We used whole-exome sequencing for gene discovery followed by targeted Sanger sequencing in a cohort of patients with MMIHS and intestinal pseudo-obstruction. We identified heterozygous ACTG2 missense variants in 15 unrelated subjects, ten being apparent de novo mutations. Ten unique variants were detected, of which six affected CpG dinucleotides and resulted in missense mutations at arginine residues, perhaps related to biased usage of CpG containing codons within actin genes. We also found some of the same heterozygous mutations that we observed as apparent de novo mutations in MMIHS segregating in families with intestinal pseudo-obstruction, suggesting that ACTG2 is responsible for a spectrum of smooth muscle disease. ACTG2 encodes γ2 enteric actin and is the first gene to be clearly associated with MMIHS, suggesting an important role for contractile proteins in enteric smooth muscle disease.

}, keywords = {Abnormalities, Multiple, Actins, Adolescent, Adult, Child, Child, Preschool, Colon, Exome, Female, Heterozygote, Humans, Intestinal Pseudo-Obstruction, Male, Muscle, Smooth, Mutation, Urinary Bladder}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1004258}, author = {Wangler, Michael F and Gonzaga-Jauregui, Claudia and Gambin, Tomasz and Penney, Samantha and Moss, Timothy and Chopra, Atul and Probst, Frank J and Xia, Fan and Yang, Yaping and Werlin, Steven and Eglite, Ieva and Kornejeva, Liene and Bacino, Carlos A and Baldridge, Dustin and Neul, Jeff and Lehman, Efrat Lev and Larson, Austin and Beuten, Joke and Muzny, Donna M and Jhangiani, Shalini and Gibbs, Richard A and Lupski, James R and Beaudet, Arthur} }