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Forman TE, Sajek MP, Larson ED, Mukherjee N, Fantauzzo KA. PDGFRα signaling regulates Srsf3 transcript binding to affect PI3K signaling and endosomal trafficking. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.03.587975. [PMID: 38617350 PMCID: PMC11014628 DOI: 10.1101/2024.04.03.587975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Signaling through the platelet-derived growth factor receptor alpha (PDGFRa) plays a critical role in craniofacial development, as mutations in PDGFRA are associated with cleft lip/palate in humans and Pdgfra mutant mouse models display varying degrees of facial clefting. Phosphatidylinositol 3-kinase (PI3K)/Akt is the primary effector of PDGFRα signaling during skeletal development in the mouse. We previously demonstrated that Akt phosphorylates the RNA-binding protein serine/arginine-rich splicing factor 3 (Srsf3) downstream of PI3K-mediated PDGFRa signaling in mouse embryonic palatal mesenchyme (MEPM) cells, leading to its nuclear translocation. We further showed that ablation of Srsf3 in the murine neural crest lineage results in severe midline facial clefting, due to defects in proliferation and survival of cranial neural crest cells, and widespread alternative RNA splicing (AS) changes. Here, we sought to determine the molecular mechanisms by which Srsf3 activity is regulated downstream of PDGFRa signaling to control AS of transcripts necessary for craniofacial development. We demonstrated via enhanced UV-crosslinking and immunoprecipitation (eCLIP) of MEPM cells that PDGF-AA stimulation leads to preferential binding of Srsf3 to exons and loss of binding to canonical Srsf3 CA-rich motifs. Through the analysis of complementary RNA-seq data, we showed that Srsf3 activity results in the preferential inclusion of exons with increased GC content and lower intron to exon length ratio. Moreover, we found that the subset of transcripts that are bound by Srsf3 and undergo AS upon PDGFRα signaling commonly encode regulators of PI3K signaling and early endosomal trafficking. Functional validation studies further confirmed that Srsf3 activity downstream of PDGFRα signaling leads to retention of the receptor in early endosomes and increases in downstream PI3K-mediated Akt signaling. Taken together, our findings reveal that growth factor-mediated phosphorylation of an RNA-binding protein underlies gene expression regulation necessary for mammalian craniofacial development.
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Affiliation(s)
- Thomas E. Forman
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Marcin P. Sajek
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Institute of Human Genetics, Polish Academy of Sciences, Poznan, Poland
| | - Eric D. Larson
- Department of Otolaryngology – Head and Neck Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Basic and Translational Sciences, Penn Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Neelanjan Mukherjee
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Katherine A. Fantauzzo
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Simpson JE, Muir MT, Lee M, Naughton C, Gilbert N, Pollard SM, Gammoh N. Autophagy supports PDGFRA-dependent brain tumor development by enhancing oncogenic signaling. Dev Cell 2024; 59:228-243.e7. [PMID: 38113891 DOI: 10.1016/j.devcel.2023.11.023] [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: 11/29/2022] [Revised: 07/29/2023] [Accepted: 11/20/2023] [Indexed: 12/21/2023]
Abstract
Autophagy is a conserved cellular degradation process. While autophagy-related proteins were shown to influence the signaling and trafficking of some receptor tyrosine kinases, the relevance of this during cancer development is unclear. Here, we identify a role for autophagy in regulating platelet-derived growth factor receptor alpha (PDGFRA) signaling and levels. We find that PDGFRA can be targeted for autophagic degradation through the activity of the autophagy cargo receptor p62. As a result, short-term autophagy inhibition leads to elevated levels of PDGFRA but an unexpected defect in PDGFA-mediated signaling due to perturbed receptor trafficking. Defective PDGFRA signaling led to its reduced levels during prolonged autophagy inhibition, suggesting a mechanism of adaptation. Importantly, PDGFA-driven gliomagenesis in mice was disrupted when autophagy was inhibited in a manner dependent on Pten status, thus highlighting a genotype-specific role for autophagy during tumorigenesis. In summary, our data provide a mechanism by which cells require autophagy to drive tumor formation.
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Affiliation(s)
- Joanne E Simpson
- Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XR, UK
| | - Morwenna T Muir
- Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XR, UK
| | - Martin Lee
- Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XR, UK
| | - Catherine Naughton
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XU, UK
| | - Nick Gilbert
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XU, UK
| | - Steven M Pollard
- Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XR, UK; Centre for Regenerative Medicine, Institute for Regeneration and Repair, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Noor Gammoh
- Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XR, UK.
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Campaña MB, Perkins MR, McCabe MC, Neumann A, Larson ED, Fantauzzo KA. PDGFRα/β heterodimer activation negatively affects downstream ERK1/2 signaling and cellular proliferation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.27.573428. [PMID: 38234806 PMCID: PMC10793460 DOI: 10.1101/2023.12.27.573428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
The platelet-derived growth factor receptor (PDGFR) family of receptor tyrosine kinases allows cells to communicate with one another by binding to growth factors at the plasma membrane and activating intracellular signaling pathways to elicit responses such as migration, proliferation, survival and differentiation. The PDGFR family consists of two receptors, PDGFRα and PDGFRβ, that dimerize to form PDGFRα homodimers, PDGFRα/β heterodimers and PDGFRβ homodimers. Here, we overcame prior technical limitations in visualizing and purifying PDGFRα/β heterodimers by generating a cell line stably expressing C-terminal fusions of PDGFRα and PDGFRβ with bimolecular fluorescence complementation fragments corresponding to the N-terminal and C-terminal regions of the Venus fluorescent protein, respectively. We found that these receptors heterodimerize relatively quickly in response to PDGF-BB ligand treatment, with a peak of receptor autophosphorylation following 5 minutes of ligand stimulation. Moreover, we demonstrated that PDGFRα/β heterodimers are rapidly internalized into early endosomes, particularly signaling endosomes, where they dwell for extended lengths of time. We showed that PDGFRα/β heterodimer activation does not induce downstream phosphorylation of ERK1/2 and significantly inhibits cell proliferation. Further, we characterized the PDGFR dimer-specific interactome and identified MYO1D as a novel protein that preferentially binds PDGFRα/β heterodimers. We demonstrated that knockdown of MYO1D leads to retention of PDGFRα/β heterodimers at the plasma membrane, resulting in increased phosphorylation of ERK1/2 and increased cell proliferation. Collectively, our findings impart valuable insight into the molecular mechanisms by which specificity is introduced downstream of PDGFR activation to differentially propagate signaling and generate distinct cellular responses.
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Affiliation(s)
- Maria B. Campaña
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Madison R. Perkins
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Maxwell C. McCabe
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Andrew Neumann
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Eric D. Larson
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Katherine A. Fantauzzo
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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Madsen RR, Toker A. PI3K signaling through a biochemical systems lens. J Biol Chem 2023; 299:105224. [PMID: 37673340 PMCID: PMC10570132 DOI: 10.1016/j.jbc.2023.105224] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/25/2023] [Accepted: 08/28/2023] [Indexed: 09/08/2023] Open
Abstract
Following 3 decades of extensive research into PI3K signaling, it is now evidently clear that the underlying network does not equate to a simple ON/OFF switch. This is best illustrated by the multifaceted nature of the many diseases associated with aberrant PI3K signaling, including common cancers, metabolic disease, and rare developmental disorders. However, we are still far from a complete understanding of the fundamental control principles that govern the numerous phenotypic outputs that are elicited by activation of this well-characterized biochemical signaling network, downstream of an equally diverse set of extrinsic inputs. At its core, this is a question on the role of PI3K signaling in cellular information processing and decision making. Here, we review the determinants of accurate encoding and decoding of growth factor signals and discuss outstanding questions in the PI3K signal relay network. We emphasize the importance of quantitative biochemistry, in close integration with advances in single-cell time-resolved signaling measurements and mathematical modeling.
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Affiliation(s)
- Ralitsa R Madsen
- MRC-Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom.
| | - Alex Toker
- Department of Pathology and Cancer Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
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Shen XW, Tang ZY, Shen XJ, Zhao JM. [Role and mechanism of platelet-derived growth factor BB in thrombocytosis in Kawasaki disease]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2023; 25:579-586. [PMID: 37382126 DOI: 10.7499/j.issn.1008-8830.2301086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
OBJECTIVES To study the role and mechanism of platelet-derived growth factor BB (PDGF-BB) on platelet production in Kawasaki disease (KD) mice and human megakaryocytic Dami cells through in vitro and invivo experiments. METHODS ELISA was used to measure the expression of PDGF in the serum of 40 children with KD and 40 healthy children. C57BL/6 mice were used to establish a model of KD and were then randomly divided into a normal group, a KD group, and an imatinib group (30 mice in each group). Routine blood test was performed for each group, and the expression of PDGF-BB, megakaryocyte colony forming unit (CFU-MK), and the megakaryocyte marker CD41 were measured. CCK-8, flow cytometry, quantitative real-time PCR, and Western blot were used to analyze the role and mechanism of PDGF-BB in platelet production in Dami cells. RESULTS PDGF-BB was highly expressed in the serum of KD children (P<0.001). The KD group had a higher expression level of PDGF-BB in serum (P<0.05) and significant increases in the expression of CFU-MK and CD41 (P<0.001), and the imatinib group had significant reductions in the expression of CFU-MK and CD41 (P<0.001). In vitro experiments showed that PDGF-BB promoted Dami cell proliferation, platelet production, mRNA expression of PDGFR-β, and protein expression of p-Akt (P<0.05). Compared with the PDGF-BB group, the combination group (PDGF-BB 25 ng/mL + imatinib 20 μmol/L) had significantly lower levels of platelet production, mRNA expression of PDGFR-β, and protein expression of p-Akt (P<0.05). CONCLUSIONS PDGF-BB may promote megakaryocyte proliferation, differentiation, and platelet production by binding to PDGFR-β and activating the PI3K/Akt pathway, and the PDGFR-β inhibitor imatinib can reduce platelet production, which provides a new strategy for the treatment of thrombocytosis in KD.
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Affiliation(s)
- Xi-Wei Shen
- Department of Pediatrics, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | | | | | - Jian-Mei Zhao
- Department of Pediatrics, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
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First person – Madison Rogers. J Cell Sci 2022. [DOI: 10.1242/jcs.260572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Madison Rogers is first author on ‘ PDGFR dimer-specific activation, trafficking and downstream signaling dynamics’, published in JCS. Madison is a PhD student in the lab of Dr Katherine A. Fantauzzo at University of Colorado Anschutz Medical Campus, Aurora, CO, USA, where she is broadly interested in cell signaling and how biological specificity is defined downstream of receptor tyrosine kinases.
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