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Innocenti M. Investigating Mammalian Formins with SMIFH2 Fifteen Years in: Novel Targets and Unexpected Biology. Int J Mol Sci 2023; 24:ijms24109058. [PMID: 37240404 DOI: 10.3390/ijms24109058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/16/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
The mammalian formin family comprises fifteen multi-domain proteins that regulate actin dynamics and microtubules in vitro and in cells. Evolutionarily conserved formin homology (FH) 1 and 2 domains allow formins to locally modulate the cell cytoskeleton. Formins are involved in several developmental and homeostatic processes, as well as human diseases. However, functional redundancy has long hampered studies of individual formins with genetic loss-of-function approaches and prevents the rapid inhibition of formin activities in cells. The discovery of small molecule inhibitor of formin homology 2 domains (SMIFH2) in 2009 was a disruptive change that provided a powerful chemical tool to explore formins' functions across biological scales. Here, I critically discuss the characterization of SMIFH2 as a pan-formin inhibitor, as well as growing evidence of unexpected off-target effects. By collating the literature and information hidden in public repositories, outstanding controversies and fundamental open questions about the substrates and mechanism of action of SMIFH2 emerge. Whenever possible, I propose explanations for these discrepancies and roadmaps to address the paramount open questions. Furthermore, I suggest that SMIFH2 be reclassified as a multi-target inhibitor for its appealing activities on proteins involved in pathological formin-dependent processes. Notwithstanding all drawbacks and limitations, SMIFH2 will continue to prove useful in studying formins in health and disease in the years to come.
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Affiliation(s)
- Metello Innocenti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
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Nishimura Y, Shi S, Li Q, Bershadsky AD, Viasnoff V. Crosstalk between myosin II and formin functions in the regulation of force generation and actomyosin dynamics in stress fibers. Cells Dev 2021; 168:203736. [PMID: 34455135 DOI: 10.1016/j.cdev.2021.203736] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/23/2021] [Accepted: 08/16/2021] [Indexed: 10/20/2022]
Abstract
REF52 fibroblasts have a well-developed contractile machinery, the most prominent elements of which are actomyosin stress fibers with highly ordered organization of actin and myosin IIA filaments. The relationship between contractile activity and turnover dynamics of stress fibers is not sufficiently understood. Here, we simultaneously measured the forces exerted by stress fibers (using traction force microscopy or micropillar array sensors) and the dynamics of actin and myosin (using photoconversion-based monitoring of actin incorporation and high-resolution fluorescence microscopy of myosin II light chain). Our data revealed new features of the crosstalk between myosin II-driven contractility and stress fiber dynamics. During normal stress fiber turnover, actin incorporated all along the stress fibers and not only at focal adhesions. Incorporation of actin into stress fibers/focal adhesions, as well as actin and myosin II filaments flow along stress fibers, strongly depends on myosin II activity. Myosin II-dependent generation of traction forces does not depend on incorporation of actin into stress fibers per se, but still requires formin activity. This previously overlooked function of formins in maintenance of the actin cytoskeleton connectivity could be the main mechanism of formin involvement in traction force generation.
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Affiliation(s)
- Yukako Nishimura
- Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, 117411, Singapore; Division of Developmental Physiology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan
| | - Shidong Shi
- Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, 117411, Singapore
| | - Qingsen Li
- IFOM-FIRC Institute of Molecular Oncology, Via Adamello, 16, 20139 Milan, Italy
| | - Alexander D Bershadsky
- Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, 117411, Singapore; Department of Molecular Cell Biology, Weizmann Institute of Science, 234 Herzl Street, POB 26, Rehovot 7610001, Israel.
| | - Virgile Viasnoff
- Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, 117411, Singapore; CNRS UMI 3639, Singapore; Department of Biological Sciences, National university of Singapore, S3 #05-01, 16 Science Drive 4, 117558, Singapore.
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Ali MF, Kawashima T. Formins control dynamics of F-actin in the central cell of Arabidopsis thaliana. Plant Signal Behav 2021; 16:1920192. [PMID: 33944667 PMCID: PMC8244771 DOI: 10.1080/15592324.2021.1920192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/16/2021] [Accepted: 04/18/2021] [Indexed: 05/28/2023]
Abstract
In the female gamete of flowering plants, sperm nuclear migration is controlled by a constant inward movement of actin filaments (F-actin) for successful fertilization. This dynamic F-actin movement is ARP2/3-independent, raising the question of how actin nucleation and polymerization is controlled in the female gamete. Using confocal microscopy live-cell imaging in combination with a pharmacological approach, we assessed the involvement of another group of actin nucleators, formins, in F-actin inward movement in the central cell of Arabidopsis thaliana. We identify that the inhibition of the formin function, by formin inhibitor SMIFH2, significantly reduced the dynamic inward movement of F-actin in the central cell, indicating that formins play a major role in actin nucleation required for F-actin inward movement in the central cell.
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Affiliation(s)
- Mohammad Foteh Ali
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Tomokazu Kawashima
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
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Sakata K, Matsuyama S, Kurebayashi N, Hayamizu K, Murayama T, Nakamura K, Kitamura K, Morimoto S, Takeya R. Differential effects of the formin inhibitor SMIFH2 on contractility and Ca 2+ handling in frog and mouse cardiomyocytes. Genes Cells 2021; 26:583-595. [PMID: 34060165 DOI: 10.1111/gtc.12873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/23/2021] [Accepted: 05/25/2021] [Indexed: 11/26/2022]
Abstract
Genetic mutations in actin regulators have been emerging as a cause of cardiomyopathy, although the functional link between actin dynamics and cardiac contraction remains largely unknown. To obtain insight into this issue, we examined the effects of pharmacological inhibition of formins, a major class of actin-assembling proteins. The formin inhibitor SMIFH2 significantly enhanced the cardiac contractility of isolated frog hearts, thereby augmenting cardiac performance. SMIFH2 treatment had no significant effects on the Ca2+ sensitivity of frog muscle fibers. Instead, it unexpectedly increased Ca2+ concentrations of isolated frog cardiomyocytes, suggesting that the inotropic effect is due to enhanced Ca2+ transients. In contrast to frog hearts, the contractility of mouse cardiomyocytes was attenuated by SMIFH2 treatment with decreasing Ca2+ transients. Thus, SMIFH2 has opposing effects on the Ca2+ transient and contractility between frog and mouse cardiomyocytes. We further found that SMIFH2 suppressed Ca2+ -release via type 2 ryanodine receptor (RyR2); this inhibitory effect may explain the species differences, since RyR2 is critical for Ca2+ transients in mouse myocardium but absent in frog myocardium. Although the mechanisms underlying the enhancement of Ca2+ transients in frog cardiomyocytes remain unclear, SMIFH2 differentially affects the cardiac contraction of amphibian and mammalian by differentially modulating their Ca2+ handling.
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Affiliation(s)
- Koji Sakata
- Department of Pharmacology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.,Department of Internal Medicine, Circulatory and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Sho Matsuyama
- Department of Pharmacology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Nagomi Kurebayashi
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, Japan
| | - Kengo Hayamizu
- Department of Clinical Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takashi Murayama
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, Japan
| | - Kunihide Nakamura
- Department of Cardiovascular Surgery, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Kazuo Kitamura
- Department of Internal Medicine, Circulatory and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Sachio Morimoto
- Department of Health Sciences Fukuoka, International University of Health and Welfare, Fukuoka, Japan
| | - Ryu Takeya
- Department of Pharmacology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
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Green HLH, Zuidscherwoude M, Alenazy F, Smith CW, Bender M, Thomas SG. SMIFH2 inhibition of platelets demonstrates a critical role for formin proteins in platelet cytoskeletal dynamics. J Thromb Haemost 2020; 18:955-967. [PMID: 31930764 PMCID: PMC7186844 DOI: 10.1111/jth.14735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 01/07/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND Reorganization of the actin cytoskeleton is required for proper functioning of platelets following activation in response to vascular damage. Formins are a family of proteins that regulate actin polymerization and cytoskeletal organization via a number of domains including the FH2 domain. However, the role of formins in platelet spreading has not been studied in detail. OBJECTIVES Several formin proteins are expressed in platelets so we used an inhibitor of FH2 domains (SMIFH2) to uncover the role of these proteins in platelet spreading and in maintenance of resting platelet shape. METHODS Washed human and mouse platelets were treated with various concentrations of SMIFH2 and the effects on platelet spreading, platelet size, platelet cytoskeletal dynamics, and organization were analyzed using fluorescence and electron microscopy. RESULTS Pretreatment with SMIFH2 completely blocks platelet spreading in both mouse and human platelets through effects on the organization and dynamics of actin and microtubules. However, platelet aggregation and secretion are unaffected. SMIFH2 also caused a decrease in resting platelet size and disrupted the balance of tubulin post-translational modification. CONCLUSIONS These data therefore demonstrated an important role for formin-mediated actin polymerization in platelet spreading and highlighted the importance of formins in cross-talk between the actin and tubulin cytoskeletons.
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Affiliation(s)
- Hannah L. H. Green
- Institute of Cardiovascular SciencesUniversity of BirminghamBirminghamUK
- Present address:
School of Cardiovascular Medicine & SciencesBHF Centre of Research ExcellenceKing's College LondonLondonUK
| | - Malou Zuidscherwoude
- Institute of Cardiovascular SciencesUniversity of BirminghamBirminghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamMidlandsUK
| | - Fawaz Alenazy
- Institute of Cardiovascular SciencesUniversity of BirminghamBirminghamUK
| | | | - Markus Bender
- Institute of Experimental Biomedicine – Chair IUniversity Hospital and Rudolf Virchow CenterWürzburgGermany
| | - Steven G. Thomas
- Institute of Cardiovascular SciencesUniversity of BirminghamBirminghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamMidlandsUK
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LeCorgne H, Tudosie AM, Lavik K, Su R, Becker KN, Moore S, Walia Y, Wisner A, Koehler D, Alberts AS, Williams FE, Eisenmann KM. Differential Toxicity of mDia Formin-Directed Functional Agonists and Antagonists in Developing Zebrafish. Front Pharmacol 2018; 9:340. [PMID: 29692731 PMCID: PMC5902741 DOI: 10.3389/fphar.2018.00340] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 03/23/2018] [Indexed: 12/16/2022] Open
Abstract
The mammalian Diaphanous-related (mDia) formins are cytoskeletal regulators that assemble and, in some cases, bundle filamentous actin (F-actin), as well as stabilize microtubules. The development of small molecule antagonists and agonists that interrogate mDia formin function has allowed us to investigate the roles of formins in disease states. A small molecule inhibitor of FH2 domain (SMIFH2) inhibits mDia-dependent actin dynamics and abrogates tumor cell migration and cell division in vitro and ex vivo tissue explants. mDia formin activation with small molecule intramimics IMM01/02 and mDia2-DAD peptides inhibited glioblastoma motility and invasion in vitro and ex vivo rat brain slices. However, SMIFH2, IMMs, and mDia2 DAD efficacy in vivo remains largely unexplored and potential toxicity across a range of developmental phenotypes has not been thoroughly characterized. In this study, we performed an in vivo screen of early life-stage toxicity in Danio rerio zebrafish embryos 2 days post-fertilization (dpf) in response to SMIFH2, IMM01/02, and mDia2 DAD. SMIFH2 at concentrations ≥5–10 μM induced significant defects in developing zebrafish, including shorter body lengths, tail curvature and defective tail cellularity, craniofacial malformations, pericardial edema, absent and/or compromised vasculature function and flow, depressed heart rates and increased mortality. Conversely, IMM and mDia2 DAD peptides were minimally toxic at concentrations up to 10–20 and 50 μM, respectively. SMIFH2's therapeutic potential may therefore be limited by its substantial in vivo toxicity at functional concentrations. mDia formin agonism with IMMs and mDia2 DADs may therefore be a more effective and less toxic anti-invasive therapeutic approach.
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Affiliation(s)
- Hunter LeCorgne
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
| | - Andrew M Tudosie
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
| | - Kari Lavik
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
| | - Robin Su
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
| | - Kathryn N Becker
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
| | - Sara Moore
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
| | - Yashna Walia
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
| | - Alexander Wisner
- Department of Pharmacology and Experimental Therapeutics, University of Toledo Health Science, Toledo, OH, United States
| | - Daniel Koehler
- Department of Pharmacology and Experimental Therapeutics, University of Toledo Health Science, Toledo, OH, United States
| | - Arthur S Alberts
- Laboratory of Cell Structure and Signal Integration, Van Andel Research Institute, Grand Rapids, MI, United States
| | - Frederick E Williams
- Department of Pharmacology and Experimental Therapeutics, University of Toledo Health Science, Toledo, OH, United States
| | - Kathryn M Eisenmann
- Department of Cancer Biology, University of Toledo Health Science, Toledo, OH, United States
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Ziske MA, Pettee KM, Khaing M, Rubinic K, Eisenmann KM. SMIFH2-mediated mDia formin functional inhibition potentiates chemotherapeutic targeting of human ovarian cancer spheroids. Biochem Biophys Res Commun 2016; 472:33-9. [PMID: 26898799 DOI: 10.1016/j.bbrc.2016.02.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 02/14/2016] [Indexed: 01/02/2023]
Abstract
Due to a lack of effective screening or prevention protocol for epithelial ovarian cancer (EOC), there is a critical unmet need to develop therapeutic interventions for EOC treatment. EOC metastasis is unique. Initial dissemination is not primarily hematogenous, yet is facilitated through shedding of primary tumor cells into the peritoneal fluid and accumulating ascites. Increasingly, isolated patient spheroids point to a clinical role for spheroids in EOC metastasis. EOC spheroids are highly invasive structures that disseminate upon peritoneal mesothelium, and visceral tissues including liver and omentum. Selection for this subset of chemoresistant EOC cells could influence disease progression and/or recurrence. Thus, targeting spheroid integrity/structure may improve the chemotherapeutic responsiveness of EOC. We discovered a critical role for mammalian Diaphanous (mDia)-related formin-2 in maintaining EOC spheroid structure. Both mDia2 and the related mDia1 regulate F-actin networks critical to maintain cell-cell contacts and the integrity of multi-cellular epithelial sheets. We investigated if mDia2 functional inhibition via a small molecule inhibitor SMIFH2 combined with chemotherapeutics, such as taxol and cisplatin, inhibits the viability of EOC monolayers and clinically relevant spheroids. SMIFH2-mediated mDia formin inhibition significantly reduced both ES2 and Skov3 EOC monolayer viability while spheroid viability was minimally impacted only at the highest concentrations. Combining either cisplatin or taxol with SMIFH2 did not significantly enhance the effects of either drug alone in ES2 monolayers, while Skov3 monolayers treated with taxol or cisplatin and SMIFH2 showed significant additive inhibition of viability. ES2 spheroids were highly responsive with clear additive anti-viability effects with dual taxol or cisplatin when combined with SMIFH2 treatments. While combined taxol with SMIFH2 in spheroids showed an additive effect relative to single treatments, Skov3 spheroids showed no additive effects from combined cisplatin and SMIFH2 treatments. Our data indicate that mDia formin inhibition combined with taxol to drive enhanced and/or additive anti-viability effects targeting 3D EOC structures, including ES2 and Skov3 spheroids. Combined mDia formin inhibition with cisplatin may be most effective in EOC spheroids where cisplatin sensitivity is retained at moderate levels, such as ES2 cells.
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Affiliation(s)
- Megan A Ziske
- Department of Biochemistry and Cancer Biology, University of Toledo Health Science Campus, Mail Stop 1010, 3000 Arlington Avenue, Toledo, OH 43614, USA
| | - Krista M Pettee
- Department of Biochemistry and Cancer Biology, University of Toledo Health Science Campus, Mail Stop 1010, 3000 Arlington Avenue, Toledo, OH 43614, USA
| | - MaNada Khaing
- Department of Biochemistry and Cancer Biology, University of Toledo Health Science Campus, Mail Stop 1010, 3000 Arlington Avenue, Toledo, OH 43614, USA
| | - Kaitlin Rubinic
- Department of Biochemistry and Cancer Biology, University of Toledo Health Science Campus, Mail Stop 1010, 3000 Arlington Avenue, Toledo, OH 43614, USA
| | - Kathryn M Eisenmann
- Department of Biochemistry and Cancer Biology, University of Toledo Health Science Campus, Mail Stop 1010, 3000 Arlington Avenue, Toledo, OH 43614, USA.
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