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Hoelzl MA, Heby-Henricson K, Gerling M, Dias JM, Kuiper RV, Trünkle C, Bergström Å, Ericson J, Toftgård R, Teglund S. Differential requirement of SUFU in tissue development discovered in a hypomorphic mouse model. Dev Biol 2017; 429:132-146. [PMID: 28688895 DOI: 10.1016/j.ydbio.2017.06.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [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: 01/27/2017] [Revised: 06/30/2017] [Accepted: 06/30/2017] [Indexed: 01/20/2023]
Abstract
Suppressor of Fused (SUFU) is an essential negative regulator of the Hedgehog (HH) pathway and involved in GLI transcription factor regulation. Due to early embryonic lethality of Sufu-/- mice, investigations of SUFU's role later in development are limited to conditional, tissue-specific knockout models. In this study we developed a mouse model (SufuEx456(fl)/Ex456(fl)) with hypomorphic features where embryos were viable up to E18.5, although with a spectrum of developmental defects of varying severity, including polydactyly, exencephaly and omphalocele. Development of certain tissues, like the skeleton, was more affected than that of others such as skin, which remained largely normal. Interestingly, no apparent changes in the dorso-ventral patterning of the neural tube at E9.0 could be seen. Thus, this model provides an opportunity to globally study SUFU's molecular function in organogenesis beyond E9.5. Molecularly, SufuEx456(fl)/Ex456(fl) embryos displayed aberrant mRNA splicing and drastically reduced levels of Sufu wild-type mRNA and SUFU protein in all tissues. As a consequence, at E9.5 the levels of all three different GLI proteins were reduced. Interestingly, despite the reduction of GLI3 protein levels, the critical ratio of the GLI3 full-length transcriptional activator versus GLI3 truncated repressor remained unchanged compared to wild-type embryos. This suggests that the limited amount of SUFU protein present is sufficient for GLI processing but not for stabilization. Our data demonstrate that tissue development is differentially affected in response to the reduced SUFU levels, providing novel insight regarding the requirements of different levels of SUFU for proper organogenesis.
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Affiliation(s)
- Maria A Hoelzl
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden.
| | - Karin Heby-Henricson
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden
| | - Marco Gerling
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden
| | - José M Dias
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Raoul V Kuiper
- Department of Laboratory Medicine, Karolinska Institutet, SE-141 86 Huddinge, Sweden
| | - Cornelius Trünkle
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden
| | - Åsa Bergström
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden
| | - Johan Ericson
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Rune Toftgård
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden
| | - Stephan Teglund
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden.
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Zhang Z, Shen L, Law K, Zhang Z, Liu X, Hua H, Li S, Huang H, Yue S, Hui CC, Cheng SY. Suppressor of Fused Chaperones Gli Proteins To Generate Transcriptional Responses to Sonic Hedgehog Signaling. Mol Cell Biol 2017; 37:e00421-16. [PMID: 27849569 PMCID: PMC5247608 DOI: 10.1128/mcb.00421-16] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 08/19/2016] [Accepted: 11/04/2016] [Indexed: 11/20/2022] Open
Abstract
Cellular responses to the graded Sonic Hedgehog (Shh) morphogenic signal are orchestrated by three Gli genes that give rise to both transcription activators and repressors. An essential downstream regulator of the pathway, encoded by the tumor suppressor gene Suppressor of fused (Sufu), plays critical roles in the production, trafficking, and function of Gli proteins, but the mechanism remains controversial. Here, we show that Sufu is upregulated in active Shh responding tissues and accompanies Gli activators translocating into and Gli repressors out of the nucleus. Trafficking of Sufu to the primary cilium, potentiated by Gli activators but not repressors, was found to be coupled to its nuclear import. We have identified a nuclear export signal (NES) motif of Sufu in juxtaposition to the protein kinase A (PKA) and glycogen synthase kinase 3 (GSK3) dual phosphorylation sites and show that Sufu binds the chromatin with both Gli1 and Gli3. Close comparison of neural tube development among individual Ptch1-/-, Sufu-/-, and Ptch1-/-; Sufu-/- double mutant embryos indicates that Sufu is critical for the maximal activation of Shh signaling essential to the specification of the most-ventral neurons. These data define Sufu as a novel class of molecular chaperone required for every aspect of Gli regulation and function.
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Affiliation(s)
- Ziyu Zhang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Longyan Shen
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Kelvin Law
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Zengdi Zhang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaotong Liu
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Hu Hua
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Sanen Li
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Huijie Huang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Shen Yue
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chi-Chung Hui
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Steven Y Cheng
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
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Yabut OR, Ng HX, Fernandez G, Yoon K, Kuhn J, Pleasure SJ. Loss of Suppressor of Fused in Mid-Corticogenesis Leads to the Expansion of Intermediate Progenitors. J Dev Biol 2016; 4:29. [PMID: 28781964 DOI: 10.3390/jdb4040029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Neural progenitors in the embryonic neocortex must be tightly regulated in order to generate the correct number and projection neuron subtypes necessary for the formation of functional neocortical circuits. In this study, we show that the intracellular protein Suppressor of Fused (Sufu) regulates the proliferation of intermediate progenitor (IP) cells at later stages of corticogenesis to affect the number of Cux1+ upper layer neurons in the postnatal neocortex. This correlates with abnormal levels of the repressor form of Gli3 (Gli3R) and the ectopic expression of Patched 1 (Ptch1), a Sonic Hedgehog (Shh) target gene. These studies reveal that the canonical role of Sufu as an inhibitor of Shh signaling is conserved at later stages of corticogenesis and that Sufu plays a crucial role in regulating neuronal number by controlling the cell cycle dynamics of IP cells in the embryonic neocortex.
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Hempel JE, Cadar AG, Hong CC. Development of thieno- and benzopyrimidinone inhibitors of the Hedgehog signaling pathway reveals PDE4-dependent and PDE4-independent mechanisms of action. Bioorg Med Chem Lett 2016; 26:1947-53. [PMID: 26976215 DOI: 10.1016/j.bmcl.2016.03.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 01/21/2016] [Revised: 03/04/2016] [Accepted: 03/05/2016] [Indexed: 10/22/2022]
Abstract
From a high content in vivo screen for modulators of developmental patterning in embryonic zebrafish, we previously identified eggmanone (EGM1, 3) as a Hedgehog (Hh) signaling inhibitor functioning downstream of Smoothened. Phenotypic optimization studies for in vitro probe development utilizing a Gli transcription-linked stable luciferase reporter cell line identified EGM1 analogs with improved potency and aqueous solubility. Mechanistic profiling of optimized analogs indicated two distinct scaffold clusters: PDE4 inhibitors able to inhibit downstream of Sufu, and PDE4-independent Hh inhibitors functioning between Smo and Sufu. Each class represents valuable in vitro probes for elucidating the complex mechanisms of Hh regulation.
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Affiliation(s)
- Jonathan E Hempel
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2220 Pierce Avenue, PRB 383, Nashville, TN 37232, USA; Vanderbilt Institute of Chemical Biology, 896 Preston Research Building, Nashville, TN 37232, USA
| | - Adrian G Cadar
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2220 Pierce Avenue, PRB 383, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232, USA
| | - Charles C Hong
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2220 Pierce Avenue, PRB 383, Nashville, TN 37232, USA; Vanderbilt Institute of Chemical Biology, 896 Preston Research Building, Nashville, TN 37232, USA; Research Medicine, Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37212, USA.
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Abstract
During the third and final larval instar stage, thousands of pluripotent cells within the Drosophila eye imaginal disc are transformed into a near perfect neurocrystalline lattice of 800 unit eyes called ommatidia. This transformation begins with the initiation of the morphogenetic furrow at the posterior margin of the eye field. The furrow, which marks the leading edge of a wave of differentiation, passes across the epithelium transforming unpatterned and undifferentiated cells into rows of periodically spaced clusters of photoreceptor neurons. As cells enter and exit the furrow they undergo dramatic alterations in cellular architecture and gene expression, many of which are required to propel the furrow forward and for proper cell fate specification. The Decapentaplegic (Dpp) and Hedgehog (Hh) signaling pathways are required for the initiation and progression of the furrow, respectively. Consistent with a role in furrow progression, the loss of Hh pathway activity results in a "furrow stop" phenotype. In contrast, reductions in levels of the helix-loop-helix transcription factor, Extramacrochaetae (Emc), lead to the polar opposite phenotype--the furrow accelerates. Recently, we demonstrated that the furrow stop and furrow acceleration phenotypes are molecularly connected. Emc appears to serve as a brake on the furrow by dampening the activity of the Hh pathway. Loss of Emc leads to an upsurge in Hh pathway activity and a faster moving furrow. The acceleration of the furrow appears to be due to an increase in levels of the full-length isoform of Cubitus Interruptus (Ci (155)) and Suppressor of Fused [Su(fu)]. Here we will briefly review the mechanisms by which Hh drives and Emc impedes the progression of the furrow across the developing retina.
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Affiliation(s)
| | - Justin P Kumar
- Department of Biology; Indiana University; Bloomington, IN USA
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