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Labat-de-Hoz L, Fernández-Martín L, Correas I, Alonso MA. INF2 formin variants linked to human inherited kidney disease reprogram the transcriptome, causing mitotic chaos and cell death. Cell Mol Life Sci 2024; 81:279. [PMID: 38916773 PMCID: PMC11335204 DOI: 10.1007/s00018-024-05323-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 06/13/2024] [Accepted: 06/14/2024] [Indexed: 06/26/2024]
Abstract
Mutations in the human INF2 gene cause autosomal dominant focal segmental glomerulosclerosis (FSGS)-a condition characterized by podocyte loss, scarring, and subsequent kidney degeneration. To understand INF2-linked pathogenicity, we examined the effect of pathogenic INF2 on renal epithelial cell lines and human primary podocytes. Our study revealed an increased incidence of mitotic cells with surplus microtubule-organizing centers fostering multipolar spindle assembly, leading to nuclear abnormalities, particularly multi-micronucleation. The levels of expression of exogenous pathogenic INF2 were similar to those of endogenous INF2. The aberrant nuclear phenotypes were observed regardless of the expression method used (retrovirus infection or plasmid transfection) or the promoter (LTR or CMV) used, and were absent with exogenous wild type INF2 expression. This indicates that the effect of pathogenic INF2 is not due to overexpression or experimental cell manipulation, but instead to the intrinsic properties of pathogenic INF2. Inactivation of the INF2 catalytic domain prevented aberrant nuclei formation. Pathogenic INF2 triggered the translocation of the transcriptional cofactor MRTF into the nucleus. RNA sequencing revealed a profound alteration in the transcriptome that could be primarily attributed to the sustained activation of the MRTF-SRF transcriptional complex. Cells eventually underwent mitotic catastrophe and death. Reducing MRTF-SRF activation mitigated multi-micronucleation, reducing the extent of cell death. Our results, if validated in animal models, could provide insights into the mechanism driving glomerular degeneration in INF2-linked FSGS and may suggest potential therapeutic strategies for impeding FSGS progression.
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Affiliation(s)
- Leticia Labat-de-Hoz
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Madrid (UAM), 28049, Madrid, Spain
| | - Laura Fernández-Martín
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Madrid (UAM), 28049, Madrid, Spain
| | - Isabel Correas
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Madrid (UAM), 28049, Madrid, Spain
- Department of Molecular Biology, UAM, 28049, Madrid, Spain
| | - Miguel A Alonso
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Madrid (UAM), 28049, Madrid, Spain.
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2
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Zhao Y, Zhang H, Wang H, Ye M, Jin X. Role of formin INF2 in human diseases. Mol Biol Rep 2021; 49:735-746. [PMID: 34698992 DOI: 10.1007/s11033-021-06869-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 10/21/2021] [Indexed: 01/08/2023]
Abstract
Formin proteins catalyze actin nucleation and microfilament polymerization. Inverted formin 2 (INF2) is an atypical diaphanous-related formin characterized by polymerization and depolymerization of actin. Accumulating evidence showed that INF2 is associated with kidney disease focal segmental glomerulosclerosis and cancers, such as colorectal and thyroid cancer where it functions as a tumor suppressor, glioblastoma, breast, prostate, and gastric cancer, via its oncogenic function. However, studies on the underlying molecular mechanisms of the different roles of INF2 in diverse cancers are limited. This review comprehensively describes the structure, biochemical features, and primary pathogenic mutations of INF2.
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Affiliation(s)
- Yiting Zhao
- Department of Hepato-Biliary-Pancreatic Surgery, The Affiliated Ningbo Medical Center of LiHuiLi Hospital of Medical School of Ningbo University, Ningbo, 315048, China.,The Affiliated Hospital of Medical School, Ningbo University, Ningbo, 315020, China
| | - Hui Zhang
- Department of Biochemistry and Molecular Biology, and Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, 315211, China.,The Affiliated Hospital of Medical School, Ningbo University, Ningbo, 315020, China
| | - Haibiao Wang
- Department of Hepato-Biliary-Pancreatic Surgery, The Affiliated Ningbo Medical Center of LiHuiLi Hospital of Medical School of Ningbo University, Ningbo, 315048, China. .,Department of Biochemistry and Molecular Biology, and Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, 315211, China.
| | - Meng Ye
- Department of Biochemistry and Molecular Biology, and Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, 315211, China. .,The Affiliated Hospital of Medical School, Ningbo University, Ningbo, 315020, China.
| | - Xiaofeng Jin
- Department of Biochemistry and Molecular Biology, and Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, 315211, China. .,The Affiliated Hospital of Medical School, Ningbo University, Ningbo, 315020, China.
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3
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Sever S. Role of actin cytoskeleton in podocytes. Pediatr Nephrol 2021; 36:2607-2614. [PMID: 33188449 PMCID: PMC8116355 DOI: 10.1007/s00467-020-04812-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/14/2020] [Accepted: 10/05/2020] [Indexed: 12/11/2022]
Abstract
The selectivity of the glomerular filter is established by physical, chemical, and signaling interplay among its three core constituents: glomerular endothelial cells, the glomerular basement membrane, and podocytes. Functional impairment or injury of any of these three components can lead to proteinuria. Podocytes are injured in many forms of human and experimental glomerular disease, including minimal change disease, focal segmental glomerulosclerosis, and diabetes mellitus. One of the earliest signs of podocyte injury is loss of their distinct structure, which is driven by dysregulated dynamics of the actin cytoskeleton. The status of the actin cytoskeleton in podocytes depends on a set of actin binding proteins, nucleators and inhibitors of actin polymerization, and regulatory GTPases. Mutations that alter protein function in each category have been implicated in glomerular diseases in humans and animal models. In addition, a growing body of studies suggest that pharmacological modifications of the actin cytoskeleton have the potential to become novel therapeutics for podocyte-dependent chronic kidney diseases. This review presents an overview of the essential proteins that establish actin cytoskeleton in podocytes and studies demonstrating the feasibility of drugging actin cytoskeleton in kidney diseases.
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Affiliation(s)
- Sanja Sever
- Harvard Medical School and Massachusetts General Hospital, Boston, MA, USA.
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4
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The Formin Fmn2b Is Required for the Development of an Excitatory Interneuron Module in the Zebrafish Acoustic Startle Circuit. eNeuro 2021; 8:ENEURO.0329-20.2021. [PMID: 34193512 PMCID: PMC8272403 DOI: 10.1523/eneuro.0329-20.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 06/11/2021] [Accepted: 06/16/2021] [Indexed: 01/22/2023] Open
Abstract
The formin family member Fmn2 is a neuronally enriched cytoskeletal remodeling protein conserved across vertebrates. Recent studies have implicated Fmn2 in neurodevelopmental disorders, including sensory processing dysfunction and intellectual disability in humans. Cellular characterization of Fmn2 in primary neuronal cultures has identified its function in the regulation of cell-substrate adhesion and consequently growth cone translocation. However, the role of Fmn2 in the development of neural circuits in vivo, and its impact on associated behaviors have not been tested. Using automated analysis of behavior and systematic investigation of the associated circuitry, we uncover the role of Fmn2b in zebrafish neural circuit development. As reported in other vertebrates, the zebrafish ortholog of Fmn2 is also enriched in the developing zebrafish nervous system. We find that Fmn2b is required for the development of an excitatory interneuron pathway, the spiral fiber neuron, which is an essential circuit component in the regulation of the Mauthner cell (M-cell)-mediated acoustic startle response. Consistent with the loss of the spiral fiber neurons tracts, high-speed video recording revealed a reduction in the short latency escape events while responsiveness to the stimuli was unaffected. Taken together, this study provides evidence for a circuit-specific requirement of Fmn2b in eliciting an essential behavior in zebrafish. Our findings underscore the importance of Fmn2 in neural development across vertebrate lineages and highlight zebrafish models in understanding neurodevelopmental disorders.
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5
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Sun H, Perez-Gill C, Schlöndorff JS, Subramanian B, Pollak MR. Dysregulated Dynein-Mediated Trafficking of Nephrin Causes INF2-related Podocytopathy. J Am Soc Nephrol 2021; 32:307-322. [PMID: 33443052 PMCID: PMC8054882 DOI: 10.1681/asn.2020081109] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 10/20/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND FSGS caused by mutations in INF2 is characterized by a podocytopathy with mistrafficked nephrin, an essential component of the slit diaphragm. Because INF2 is a formin-type actin nucleator, research has focused on its actin-regulating function, providing an important but incomplete insight into how these mutations lead to podocytopathy. A yeast two-hybridization screen identified the interaction between INF2 and the dynein transport complex, suggesting a newly recognized role of INF2 in regulating dynein-mediated vesicular trafficking in podocytes. METHODS Live cell and quantitative imaging, fluorescent and surface biotinylation-based trafficking assays in cultured podocytes, and a new puromycin aminoglycoside nephropathy model of INF2 transgenic mice were used to demonstrate altered dynein-mediated trafficking of nephrin in INF2 associated podocytopathy. RESULTS Pathogenic INF2 mutations disrupt an interaction of INF2 with dynein light chain 1, a key dynein component. The best-studied mutation, R218Q, diverts dynein-mediated postendocytic sorting of nephrin from recycling endosomes to lysosomes for degradation. Antagonizing dynein-mediated transport can rescue this effect. Augmented dynein-mediated trafficking and degradation of nephrin underlies puromycin aminoglycoside-induced podocytopathy and FSGS in vivo. CONCLUSIONS INF2 mutations enhance dynein-mediated trafficking of nephrin to proteolytic pathways, diminishing its recycling required for maintaining slit diaphragm integrity. The recognition that dysregulated dynein-mediated transport of nephrin in R218Q knockin podocytes opens an avenue for developing targeted therapy for INF2-mediated FSGS.
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Affiliation(s)
- Hua Sun
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
- Renal Division, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
- Stead Family Department of Pediatrics, University of Iowa, Iowa City, Iowa
| | - Chandra Perez-Gill
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Johannes S Schlöndorff
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Balajikarthick Subramanian
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Martin R. Pollak
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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6
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Bayraktar S, Nehrig J, Menis E, Karli K, Janning A, Struk T, Halbritter J, Michgehl U, Krahn MP, Schuberth CE, Pavenstädt H, Wedlich-Söldner R. A Deregulated Stress Response Underlies Distinct INF2-Associated Disease Profiles. J Am Soc Nephrol 2021; 31:1296-1313. [PMID: 32444357 DOI: 10.1681/asn.2019111174] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/20/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Monogenic diseases provide favorable opportunities to elucidate the molecular mechanisms of disease progression and improve medical diagnostics. However, the complex interplay between genetic and environmental factors in disease etiologies makes it difficult to discern the mechanistic links between different alleles of a single locus and their associated pathophysiologies. Inverted formin 2 (INF2), an actin regulator, mediates a stress response-calcium mediated actin reset, or CaAR-that reorganizes the actin cytoskeleton of mammalian cells in response to calcium influx. It has been linked to the podocytic kidney disease focal segemental glomerulosclerosis (FSGS), as well as to cases of the neurologic disorder Charcot-Marie-Tooth disease that are accompanied by nephropathy, mostly FSGS. METHODS We used a combination of quantitative live cell imaging and validation in primary patient cells and Drosophila nephrocytes to systematically characterize a large panel of >50 autosomal dominant INF2 mutants that have been reported to cause either FSGS alone or with Charcot-Marie-Tooth disease. RESULTS We found that INF2 mutations lead to deregulated activation of formin and a constitutive stress response in cultured cells, primary patient cells, and Drosophila nephrocytes. We were able to clearly distinguish between INF2 mutations that were linked exclusively to FSGS from those that caused a combination of FSGS and Charcot-Marie-Tooth disease. Furthermore, we were able to identify distinct subsets of INF2 variants that exhibit varying degrees of activation. CONCLUSIONS Our results suggest that CaAR can be used as a sensitive assay for INF2 function and for robust evaluation of diseased-linked variants of formin. More broadly, these findings indicate that cellular profiling of disease-associated mutations has potential to contribute substantially to sequence-based phenotype predictions.
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Affiliation(s)
- Samet Bayraktar
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany.,Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Julian Nehrig
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Ekaterina Menis
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Kevser Karli
- Medical Cell Biology, Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Annette Janning
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Thaddäus Struk
- Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Jan Halbritter
- Division of Nephrology, University of Leipzig, Leipzig, Germany
| | - Ulf Michgehl
- Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Michael P Krahn
- Medical Cell Biology, Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Christian E Schuberth
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | | | - Roland Wedlich-Söldner
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
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7
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The actin polymerization factor Diaphanous and the actin severing protein Flightless I collaborate to regulate sarcomere size. Dev Biol 2021; 469:12-25. [PMID: 32980309 DOI: 10.1016/j.ydbio.2020.09.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 09/15/2020] [Accepted: 09/19/2020] [Indexed: 12/22/2022]
Abstract
The sarcomere is the basic contractile unit of muscle, composed of repeated sets of actin thin filaments and myosin thick filaments. During muscle development, sarcomeres grow in size to accommodate the growth and function of muscle fibers. Failure in regulating sarcomere size results in muscle dysfunction; yet, it is unclear how the size and uniformity of sarcomeres are controlled. Here we show that the formin Diaphanous is critical for the growth and maintenance of sarcomere size: Dia sets sarcomere length and width through regulation of the number and length of the actin thin filaments in the Drosophila flight muscle. To regulate thin filament length and sarcomere size, Dia interacts with the Gelsolin superfamily member Flightless I (FliI). We suggest that these actin regulators, by controlling actin dynamics and turnover, generate uniformly sized sarcomeres tuned for the muscle contractions required for flight.
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8
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Schneider R, Deutsch K, Hoeprich GJ, Marquez J, Hermle T, Braun DA, Seltzsam S, Kitzler TM, Mao Y, Buerger F, Majmundar AJ, Onuchic-Whitford AC, Kolvenbach CM, Schierbaum L, Schneider S, Halawi AA, Nakayama M, Mann N, Connaughton DM, Klämbt V, Wagner M, Riedhammer KM, Renders L, Katsura Y, Thumkeo D, Soliman NA, Mane S, Lifton RP, Shril S, Khokha MK, Hoefele J, Goode BL, Hildebrandt F. DAAM2 Variants Cause Nephrotic Syndrome via Actin Dysregulation. Am J Hum Genet 2020; 107:1113-1128. [PMID: 33232676 DOI: 10.1016/j.ajhg.2020.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/05/2020] [Indexed: 01/10/2023] Open
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.
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9
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Labat-de-Hoz L, Alonso MA. The formin INF2 in disease: progress from 10 years of research. Cell Mol Life Sci 2020; 77:4581-4600. [PMID: 32451589 PMCID: PMC11104792 DOI: 10.1007/s00018-020-03550-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 05/04/2020] [Accepted: 05/13/2020] [Indexed: 02/07/2023]
Abstract
Formins are a conserved family of proteins that primarily act to form linear polymers of actin. Despite their importance to the normal functioning of the cytoskeleton, for a long time, the only two formin genes known to be a genetic cause of human disorders were DIAPH1 and DIAPH3, whose mutation causes two distinct forms of hereditary deafness. In the last 10 years, however, the formin INF2 has emerged as an important target of mutations responsible for the appearance of focal segmental glomerulosclerosis, which are histological lesions associated with glomerulus degeneration that often leads to end-stage renal disease. In some rare cases, focal segmental glomerulosclerosis concurs with Charcot-Marie-Tooth disease, which is a degenerative neurological disorder affecting peripheral nerves. All known INF2 gene mutations causing disease map to the exons encoding the amino-terminal domain. In this review, we summarize the structure, biochemical features and functions of INF2, conduct a systematic and comprehensive analysis of the pathogenic INF2 mutations, including a detailed study exon-by-exon of patient cases and mutations, address the impact of the pathogenic mutations on the structure, regulation and known functions of INF2, draw a series of conclusions that could be useful for INF2-related disease diagnosis, and suggest lines of research for future work on the molecular mechanisms by which INF2 causes disease.
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Affiliation(s)
- Leticia Labat-de-Hoz
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel A Alonso
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain.
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10
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Hansen KUI, Siegerist F, Daniel S, Schindler M, Iervolino A, Blumenthal A, Daniel C, Amann K, Zhou W, Endlich K, Endlich N. Prolonged podocyte depletion in larval zebrafish resembles mammalian focal and segmental glomerulosclerosis. FASEB J 2020; 34:15961-15974. [PMID: 33070374 DOI: 10.1096/fj.202000724r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022]
Abstract
Focal and segmental glomerulosclerosis (FSGS) is a histological pattern frequently found in patients with nephrotic syndrome that often progress to end-stage kidney disease. The initial step in development of this histologically defined entity is injury and ultimately depletion of podocytes, highly arborized interdigitating cells on the glomerular capillaries with important function for the glomerular filtration barrier. Since there are still no causal therapeutic options, animal models are needed to develop new treatment strategies. Here, we present an FSGS-like model in zebrafish larvae, an eligible vertebrate model for kidney research. In a transgenic zebrafish strain, podocytes were depleted, and the glomerular response was investigated by histological and morphometrical analysis combined with immunofluorescence staining and ultrastructural analysis by transmission electron microscopy. By intravenous injection of fluorescent high-molecular weight dextran, we confirmed leakage of the size selective filtration barrier. Additionally, we observed severe podocyte foot process effacement of remaining podocytes, activation of proximal tubule-like parietal epithelial cells identified by ultrastructural cytomorphology, and expression of proximal tubule markers. These activated cells deposited extracellular matrix on the glomerular tuft which are all hallmarks of FSGS. Our findings indicate that glomerular response to podocyte depletion in larval zebrafish resembles human FSGS in several important characteristics. Therefore, this model will help to investigate the disease development and the effects of potential drugs in a living organism.
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Affiliation(s)
| | - Florian Siegerist
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Sophie Daniel
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Maximilian Schindler
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Anna Iervolino
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany.,Biogem Research Institute Gaetano Salvatore, Ariano Irpino, Italy
| | - Antje Blumenthal
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Christoph Daniel
- Department of Nephropathology, Institute of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Institute of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Weibin Zhou
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Karlhans Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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11
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Krendel M, Pruyne D. New Paradigm for Cytoskeletal Organization in Podocytes: Proteolytic Fragments of INF2 Formin Function Independently of INF2 Actin Regulatory Activity. J Am Soc Nephrol 2020; 31:235-236. [PMID: 31924669 DOI: 10.1681/asn.2019121292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Mira Krendel
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - David Pruyne
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
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12
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Müller-Deile J, Schenk H, Niggemann P, Bolaños-Palmieri P, Teng B, Higgs A, Staggs L, Haller H, Schroder P, Schiffer M. Mutation of microphthalmia-associated transcription factor (mitf) in zebrafish sensitizes for glomerulopathy. Biol Open 2019; 8:bio.040253. [PMID: 30718228 PMCID: PMC6451330 DOI: 10.1242/bio.040253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Different glomerular diseases that affect podocyte homeostasis can clinically present as nephrotic syndrome with massive proteinuria, hypoalbuminemia, hyperlipidemia and edema. Up to now, no drugs that specifically target the actin cytoskeleton of podocytes are on the market and model systems for library screenings to develop anti-proteinuric drugs are of high interest. We developed a standardized proteinuria model in zebrafish using puromycin aminonucleoside (PAN) via treatment in the fish water to allow for further drug testing to develop anti-proteinuric drugs for the treatment of glomerular diseases. We noticed that fish that carry the nacre-mutation show a significantly higher susceptibility for the disruption of the glomerular filtration barrier following PAN treatment, which results in a more pronounced proteinuria phenotype. Nacre zebrafish inherit a mutation yielding a truncated version of microphthalmia-associated transcription factor/melanogenesis associated transcription factor (mitf). We hypothesized that the nacre mutation may lead to reduced formin expression and defects in cytoskeletal rearrangement. Based on the observations in zebrafish, we carried out a PAN treatment on cultured human podocytes after knockdown with MITF siRNA causing a rearrangement of the actin cytoskeleton.
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Affiliation(s)
- Janina Müller-Deile
- Department of Nephrology, Hannover Medical School, Hannover 30625, Germany.,Department of Nephrology and Hypertension, University of Erlangen-Nurnberg, Erlangen 91054, Germany
| | - Heiko Schenk
- Department of Nephrology, Hannover Medical School, Hannover 30625, Germany.,Division of Nephrology, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04609, USA
| | - Philipp Niggemann
- Department of Nephrology, Hannover Medical School, Hannover 30625, Germany.,Division of Nephrology, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04609, USA
| | - Patricia Bolaños-Palmieri
- Department of Nephrology, Hannover Medical School, Hannover 30625, Germany.,Department of Nephrology and Hypertension, University of Erlangen-Nurnberg, Erlangen 91054, Germany
| | - Beina Teng
- Department of Nephrology, Hannover Medical School, Hannover 30625, Germany.,Department of Nephrology and Hypertension, University of Erlangen-Nurnberg, Erlangen 91054, Germany
| | - Alysha Higgs
- Division of Nephrology, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04609, USA
| | - Lynne Staggs
- Division of Nephrology, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04609, USA
| | - Hermann Haller
- Department of Nephrology, Hannover Medical School, Hannover 30625, Germany.,Division of Nephrology, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04609, USA
| | - Patricia Schroder
- Division of Nephrology, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04609, USA
| | - Mario Schiffer
- Department of Nephrology, Hannover Medical School, Hannover 30625, Germany .,Department of Nephrology and Hypertension, University of Erlangen-Nurnberg, Erlangen 91054, Germany
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13
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Elmonem MA, Berlingerio SP, van den Heuvel LP, de Witte PA, Lowe M, Levtchenko EN. Genetic Renal Diseases: The Emerging Role of Zebrafish Models. Cells 2018; 7:cells7090130. [PMID: 30200518 PMCID: PMC6162634 DOI: 10.3390/cells7090130] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Abstract
The structural and functional similarity of the larval zebrafish pronephros to the human nephron, together with the recent development of easier and more precise techniques to manipulate the zebrafish genome have motivated many researchers to model human renal diseases in the zebrafish. Over the last few years, great advances have been made, not only in the modeling techniques of genetic diseases in the zebrafish, but also in how to validate and exploit these models, crossing the bridge towards more informative explanations of disease pathophysiology and better designed therapeutic interventions in a cost-effective in vivo system. Here, we review the significant progress in these areas giving special attention to the renal phenotype evaluation techniques. We further discuss the future applications of such models, particularly their role in revealing new genetic diseases of the kidney and their potential use in personalized medicine.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, 11628 Cairo, Egypt.
| | - Sante Princiero Berlingerio
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Pediatric Nephrology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands.
| | - Peter A de Witte
- Laboratory for Molecular Bio-Discovery, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven-University of Leuven, 3000 Leuven, Belgium.
| | - Martin Lowe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK.
| | - Elena N Levtchenko
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
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14
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Hegsted A, Yingling CV, Pruyne D. Inverted formins: A subfamily of atypical formins. Cytoskeleton (Hoboken) 2017; 74:405-419. [PMID: 28921928 DOI: 10.1002/cm.21409] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 08/22/2017] [Accepted: 08/31/2017] [Indexed: 12/25/2022]
Abstract
Formins are a family of regulators of actin and microtubule dynamics that are present in almost all eukaryotes. These proteins are involved in many cellular processes, including cytokinesis, stress fiber formation, and cell polarization. Here we review one subfamily of formins, the inverted formins. Inverted formins as a group break several formin stereotypes, having atypical biochemical properties and domain organization, and they have been linked to kidney disease and neuropathy in humans. In this review, we will explore recent research on members of the inverted formin sub-family in mammals, zebrafish, fruit flies, and worms.
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Affiliation(s)
- Anna Hegsted
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Curtis V Yingling
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - David Pruyne
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
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15
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Abstract
Podocytes exhibit a unique cytoskeletal architecture that is fundamentally linked to their function in maintaining the kidney filtration barrier. The cytoskeleton regulates podocyte shape, structure, stability, slit diaphragm insertion, adhesion, plasticity, and dynamic response to environmental stimuli. Genetic mutations demonstrate that even slight impairment of the podocyte cytoskeletal apparatus results in proteinuria and glomerular disease. Moreover, mechanisms underpinning all acquired glomerular pathologies converge on disruption of the cytoskeleton, suggesting that this subcellular structure could be targeted for therapeutic purposes. This review summarizes our current understanding of the function of the cytoskeleton in podocytes and the associated implications for pathophysiology.
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Affiliation(s)
- Christoph Schell
- Institute of Surgical Pathology and.,Department of Medicine IV, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Tobias B Huber
- Department of Medicine IV, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; .,III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and.,BIOSS Centre for Biological Signalling Studies and Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University, Freiburg, Germany
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16
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Liu J, Wang W. Genetic basis of adult-onset nephrotic syndrome and focal segmental glomerulosclerosis. Front Med 2017; 11:333-339. [PMID: 28776307 DOI: 10.1007/s11684-017-0564-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/02/2017] [Indexed: 12/22/2022]
Abstract
Nephrotic syndrome (NS) is one of the most common glomerular diseases with signs of nephrosis, heavy proteinuria, hypoalbuminemia, and edema. Dysfunction of glomerular filtration barrier causes protein loss through the kidneys. Focal segmental glomerulosclerosis (FSGS) accounts for nearly 20% of NS among children and adults. Adult-onset FSGS/NS is often associated with low response to steroid treatment and immunosuppressive medication and poor renal survival. Several genes involved in NS and FSGS have been identified by linkage analysis and next-generation sequencing. Most of these genes encode proteins and are highly expressed in glomerular podocytes, which play crucial roles in slit-diaphragm signaling, regulation of actin cytoskeleton dynamics and maintenance of podocyte integrity, and cell-matrix interactions. In this review, we focus on the recently identified genes in the adult-onset NS and FSGS and discuss clinical significance of screening of these genes.
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Affiliation(s)
- Jian Liu
- Institute of Nephrology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.,Department of Nephrology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Weiming Wang
- Institute of Nephrology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China. .,Department of Nephrology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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17
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Schenk H, Müller-Deile J, Kinast M, Schiffer M. Disease modeling in genetic kidney diseases: zebrafish. Cell Tissue Res 2017; 369:127-141. [PMID: 28331970 DOI: 10.1007/s00441-017-2593-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/22/2017] [Indexed: 01/07/2023]
Abstract
Growing numbers of translational genomics studies are based on the highly efficient and versatile zebrafish (Danio rerio) vertebrate model. The increasing types of zebrafish models have improved our understanding of inherited kidney diseases, since they not only display pathophysiological changes but also give us the opportunity to develop and test novel treatment options in a high-throughput manner. New paradigms in inherited kidney diseases have been developed on the basis of the distinct genome conservation of approximately 70 % between zebrafish and humans in terms of existing gene orthologs. Several options are available to determine the functional role of a specific gene or gene sets. Permanent genome editing can be induced via complete gene knockout by using the CRISPR/Cas-system, among others, or via transient modification by using various morpholino techniques. Cross-species rescues succeeding knockdown techniques are employed to determine the functional significance of a target gene or a specific mutation. This article summarizes the current techniques and discusses their perspectives.
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Affiliation(s)
- Heiko Schenk
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA
| | - Janina Müller-Deile
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA
| | - Mark Kinast
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA
| | - Mario Schiffer
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany.
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA.
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18
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Shaye DD, Greenwald I. A network of conserved formins, regulated by the guanine exchange factor EXC-5 and the GTPase CDC-42, modulates tubulogenesis in vivo. Development 2016; 143:4173-4181. [PMID: 27697907 DOI: 10.1242/dev.141861] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/20/2016] [Indexed: 12/20/2022]
Abstract
The C. elegans excretory cell (EC) is a powerful model for tubulogenesis, a conserved process that requires precise cytoskeletal regulation. EXC-6, an ortholog of the disease-associated formin INF2, coordinates cell outgrowth and lumen formation during EC tubulogenesis by regulating F-actin at the tip of the growing canal and the dynamics of basolateral microtubules. EXC-6 functions in parallel with EXC-5/FGD, a predicted activator of the Rho GTPase Cdc42. Here, we identify the parallel pathway: EXC-5 functions through CDC-42 to regulate two other formins: INFT-2, another INF2 ortholog, and CYK-1, the sole ortholog of the mammalian diaphanous (mDia) family of formins. We show that INFT-2 promotes F-actin accumulation in the EC, and that CYK-1 inhibits INFT-2 to regulate F-actin levels and EXC-6-promoted outgrowth. As INF2 and mDia physically interact and cross-regulate in cultured cells, our work indicates that a conserved EXC-5-CDC-42 pathway modulates this regulatory interaction and that it is functionally important in vivo during tubulogenesis.
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Affiliation(s)
- Daniel D Shaye
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA .,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.,Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Iva Greenwald
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
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19
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Subramanian B, Sun H, Yan P, Charoonratana VT, Higgs HN, Wang F, Lai KMV, Valenzuela DM, Brown EJ, Schlöndorff JS, Pollak MR. Mice with mutant Inf2 show impaired podocyte and slit diaphragm integrity in response to protamine-induced kidney injury. Kidney Int 2016; 90:363-372. [PMID: 27350175 DOI: 10.1016/j.kint.2016.04.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/18/2016] [Accepted: 04/28/2016] [Indexed: 01/08/2023]
Abstract
Mutations in the INF2 (inverted formin 2) gene, encoding a diaphanous formin family protein that regulates actin cytoskeleton dynamics, cause human focal segmental glomerulosclerosis (FSGS). INF2 interacts directly with certain other mammalian diaphanous formin proteins (mDia) that function as RhoA effector molecules. FSGS-causing INF2 mutations impair these interactions and disrupt the ability of INF2 to regulate Rho/Dia-mediated actin dynamics in vitro. However, the precise mechanisms by which INF2 regulates and INF2 mutations impair glomerular structure and function remain unknown. Here, we characterize an Inf2 R218Q point-mutant (knockin) mouse to help answer these questions. Knockin mice have no significant renal pathology or proteinuria at baseline despite diminished INF2 protein levels. INF2 mutant podocytes do show impaired reversal of protamine sulfate-induced foot process effacement by heparin sulfate perfusion. This is associated with persistent podocyte cytoplasmic aggregation, nephrin phosphorylation, and nephrin and podocin mislocalization, as well as impaired recovery of mDia membrane localization. These changes were partially mimicked in podocyte outgrowth cultures, in which podocytes from knockin mice show altered cellular protrusions compared to those from wild-type mice. Thus, in mice, normal INF2 function is not required for glomerular development but normal INF2 is required for regulation of the actin-based behaviors necessary for response to and/or recovery from injury.
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Affiliation(s)
- Balajikarthick Subramanian
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Hua Sun
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; University of Children's Hospital, Iowa City, Iowa, USA
| | - Paul Yan
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Victoria T Charoonratana
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Henry N Higgs
- Department of Biochemistry, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Fang Wang
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Ka-Man V Lai
- Regeneron Pharmaceuticals, Tarrytown, New York, USA
| | | | - Elizabeth J Brown
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; Division of Nephrology, Department of Pediatrics, Children's Hospital, Boston, Massachusetts, USA; Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Johannes S Schlöndorff
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Martin R Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
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20
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Abstract
Podocytes are highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule. When it comes to glomerular filtration, podocytes play an active role in preventing plasma proteins from entering the urinary ultrafiltrate by providing a barrier comprising filtration slits between foot processes, which in aggregate represent a dynamic network of cellular extensions. Foot processes interdigitate with foot processes from adjacent podocytes and form a network of narrow and rather uniform gaps. The fenestrated endothelial cells retain blood cells but permit passage of small solutes and an overlying basement membrane less permeable to macromolecules, in particular to albumin. The cytoskeletal dynamics and structural plasticity of podocytes as well as the signaling between each of these distinct layers are essential for an efficient glomerular filtration and thus for proper renal function. The genetic or acquired impairment of podocytes may lead to foot process effacement (podocyte fusion or retraction), a morphological hallmark of proteinuric renal diseases. Here, we briefly discuss aspects of a contemporary view of podocytes in glomerular filtration, the patterns of structural changes in podocytes associated with common glomerular diseases, and the current state of basic and clinical research.
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Affiliation(s)
- Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
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21
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Disease causing mutations in inverted formin 2 regulate its binding to G-actin, F-actin capping protein (CapZ α-1) and profilin 2. Biosci Rep 2016; 36:e00302. [PMID: 26764407 PMCID: PMC4770304 DOI: 10.1042/bsr20150252] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/12/2016] [Indexed: 01/07/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a devastating form of nephrotic syndrome which ultimately leads to end stage renal failure (ESRF). Mutations in inverted formin 2 (INF2), a member of the formin family of actin-regulating proteins, have recently been associated with a familial cause of nephrotic syndrome characterized by FSGS. INF2 is a unique formin that can both polymerize and depolymerize actin filaments. How mutations in INF2 lead to disease is unknown. In the present study, we show that three mutations associated with FSGS, E184K, S186P and R218Q, reduce INF2 auto-inhibition and increase association with monomeric actin. Furthermore using a combination of GFP-INF2 expression in human podocytes and GFP-Trap purification coupled with MS we demonstrate that INF2 interacts with profilin 2 and the F-actin capping protein, CapZ α-1. These interactions are increased by the presence of the disease causing mutations. Since both these proteins are involved in the dynamic turnover and restructuring of the actin cytoskeleton these changes strengthen the evidence that aberrant regulation of actin dynamics underlies the pathogenesis of disease.
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