1
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Holmes MJ, Bastos MS, Dey V, Severo V, Wek RC, Sullivan WJ. mRNA cap-binding protein eIF4E1 is a novel regulator of Toxoplasma gondii latency. mBio 2024; 15:e0295423. [PMID: 38747593 PMCID: PMC11237481 DOI: 10.1128/mbio.02954-23] [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: 11/03/2023] [Accepted: 04/15/2024] [Indexed: 05/28/2024] Open
Abstract
The protozoan parasite Toxoplasma gondii causes serious opportunistic disease due to its ability to persist in patients as latent tissue cysts. The molecular mechanisms coordinating conversion between proliferative parasites (tachyzoites) and latent cysts (bradyzoites) are not fully understood. We previously showed that phosphorylation of eIF2α accompanies bradyzoite formation, suggesting that this clinically relevant process involves regulation of mRNA translation. In this study, we investigated the composition and role of eIF4F multi-subunit complexes in translational control. Using CLIPseq, we find that the cap-binding subunit, eIF4E1, localizes to the 5'-end of all tachyzoite mRNAs, many of which show evidence of stemming from heterogeneous transcriptional start sites. We further show that eIF4E1 operates as the predominant cap-binding protein in two distinct eIF4F complexes. Using genetic and pharmacological approaches, we found that eIF4E1 deficiency triggers efficient spontaneous formation of bradyzoites without stress induction. Consistent with this result, we also show that stress-induced bradyzoites exhibit reduced eIF4E1 expression. Overall, our findings establish a novel role for eIF4F in translational control required for parasite latency and microbial persistence. IMPORTANCE Toxoplasma gondii is an opportunistic pathogen important to global human and animal health. There are currently no chemotherapies targeting the encysted form of the parasite. Consequently, a better understanding of the mechanisms controlling encystation is required. Here we show that the mRNA cap-binding protein, eIF4E1, regulates the encystation process. Encysted parasites reduce eIF4E1 levels, and depletion of eIF4E1 decreases the translation of ribosome-associated machinery and drives Toxoplasma encystation. Together, these data reveal a new layer of mRNA translational control that regulates parasite encystation and latency.
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Affiliation(s)
- Michael J Holmes
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Matheus S Bastos
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Vishakha Dey
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Vanessa Severo
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ronald C Wek
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - William J Sullivan
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Microbiology & Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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2
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Wang F, Holmes MJ, Hong HJ, Thaprawat P, Kannan G, Huynh MH, Schultz TL, Licon MH, Lourido S, Dong W, Brito Querido J, Sullivan WJ, O'Leary SE, Carruthers VB. Translation initiation factor eIF1.2 promotes Toxoplasma stage conversion by regulating levels of key differentiation factors. Nat Commun 2024; 15:4385. [PMID: 38782906 PMCID: PMC11116398 DOI: 10.1038/s41467-024-48685-4] [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: 11/16/2023] [Accepted: 05/07/2024] [Indexed: 05/25/2024] Open
Abstract
The parasite Toxoplasma gondii persists in its hosts by converting from replicating tachyzoites to latent bradyzoites housed in tissue cysts. The molecular mechanisms that mediate T. gondii differentiation remain poorly understood. Through a mutagenesis screen, we identified translation initiation factor eIF1.2 as a critical factor for T. gondii differentiation. A F97L mutation in eIF1.2 or the genetic ablation of eIF1.2 (∆eif1.2) markedly impeded bradyzoite cyst formation in vitro and in vivo. We demonstrated, at single-molecule level, that the eIF1.2 F97L mutation impacts the scanning process of the ribosome preinitiation complex on a model mRNA. RNA sequencing and ribosome profiling experiments unveiled that ∆eif1.2 parasites are defective in upregulating bradyzoite induction factors BFD1 and BFD2 during stress-induced differentiation. Forced expression of BFD1 or BFD2 significantly restored differentiation in ∆eif1.2 parasites. Together, our findings suggest that eIF1.2 functions by regulating the translation of key differentiation factors necessary to establish chronic toxoplasmosis.
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Affiliation(s)
- Fengrong Wang
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Michael J Holmes
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Hea Jin Hong
- Department of Biochemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Pariyamon Thaprawat
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Tracey L Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | | | - Sebastian Lourido
- Whitehead Institute, Cambridge, MA, 02142, USA
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, 02142, USA
| | - Wenzhao Dong
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
- Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jailson Brito Querido
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
- Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - William J Sullivan
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Microbiology & Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Seán E O'Leary
- Department of Biochemistry, University of California Riverside, Riverside, CA, 92521, USA
- Center for RNA Biology and Medicine, University of California Riverside, Riverside, CA, 92521, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
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3
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Wang F, Holmes MJ, Hong HJ, Thaprawat P, Kannan G, Huynh MH, Schultz TL, Licon MH, Lourido S, Dong W, Querido JB, Sullivan WJ, O'Leary SE, Carruthers VB. Translation initiation factor eIF1.2 promotes Toxoplasma stage conversion by regulating levels of key differentiation factors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.03.565545. [PMID: 37961607 PMCID: PMC10635126 DOI: 10.1101/2023.11.03.565545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The parasite Toxoplasma gondii persists in its hosts by converting from replicating tachyzoites to latent bradyzoites housed in tissue cysts. The molecular mechanisms that mediate T. gondii differentiation remain poorly understood. Through a mutagenesis screen, we identified translation initiation factor eIF1.2 as a critical factor for T. gondii differentiation. A F97L mutation in eIF1.2 or the genetic ablation of eIF1.2 (Δ eif1.2 ) markedly impeded bradyzoite cyst formation in vitro and in vivo . We demonstrated, at single-molecule level, that the eIF1.2 F97L mutation impacts the scanning process of the ribosome preinitiation complex on a model mRNA. RNA sequencing and ribosome profiling experiments unveiled that Δ eif1.2 parasites are defective in upregulating bradyzoite induction factors BFD1 and BFD2 during stress-induced differentiation. Forced expression of BFD1 or BFD2 significantly restored differentiation in Δ eif1.2 parasites. Together, our findings suggest that eIF1.2 functions by regulating the translation of key differentiation factors necessary to establish chronic toxoplasmosis.
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4
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Danan CH, Naughton KE, Hayer KE, Vellappan S, McMillan EA, Zhou Y, Matsuda R, Nettleford SK, Katada K, Parham LR, Ma X, Chowdhury A, Wilkins BJ, Shah P, Weitzman MD, Hamilton KE. Intestinal transit-amplifying cells require METTL3 for growth factor signaling and cell survival. JCI Insight 2023; 8:e171657. [PMID: 37883185 PMCID: PMC10795831 DOI: 10.1172/jci.insight.171657] [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: 04/24/2023] [Accepted: 10/25/2023] [Indexed: 10/27/2023] Open
Abstract
Intestinal epithelial transit-amplifying cells are essential stem progenitors required for intestinal homeostasis, but their rapid proliferation renders them vulnerable to DNA damage from radiation and chemotherapy. Despite these cells' critical roles in intestinal homeostasis and disease, few studies have described genes that are essential to transit-amplifying cell function. We report that RNA methyltransferase-like 3 (METTL3) is required for survival of transit-amplifying cells in the murine small intestine. Transit-amplifying cell death after METTL3 deletion was associated with crypt and villus atrophy, loss of absorptive enterocytes, and uniform wasting and death in METTL3-depleted mice. Sequencing of polysome-bound and methylated RNAs in enteroids and in vivo demonstrated decreased translation of hundreds of methylated transcripts after METTL3 deletion, particularly transcripts involved in growth factor signal transduction such as Kras. Further investigation verified a relationship between METTL3 and Kras methylation and protein levels in vivo. Our study identifies METTL3 as an essential factor supporting the homeostasis of small intestinal tissue via direct maintenance of transit-amplifying cell survival. We highlight the crucial role of RNA modifications in regulating growth factor signaling in the intestine with important implications for both homeostatic tissue renewal and epithelial regeneration.
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Affiliation(s)
- Charles H. Danan
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
- Medical Scientist Training Program, Perelman School of Medicine; and
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kaitlyn E. Naughton
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
| | - Katharina E. Hayer
- Department of Biomedical and Health Informatics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Division of Protective Immunity, Children’s Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine; University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sangeevan Vellappan
- Waksman Institute of Microbiology and
- Department of Genetics, Rutgers University, Piscataway, New Jersey, USA
- Human Genetics Institute of New Jersey, Piscataway, New Jersey, USA
| | - Emily A. McMillan
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
| | - Yusen Zhou
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
- Department of Biomedical and Health Informatics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Rina Matsuda
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Pathobiology, School of Veterinary Medicine, and
| | - Shaneice K. Nettleford
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
| | - Kay Katada
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Louis R. Parham
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Xianghui Ma
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
| | - Afrah Chowdhury
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
| | - Benjamin J. Wilkins
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine; University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Premal Shah
- Department of Genetics, Rutgers University, Piscataway, New Jersey, USA
- Human Genetics Institute of New Jersey, Piscataway, New Jersey, USA
| | - Matthew D. Weitzman
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Protective Immunity, Children’s Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine; University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kathryn E. Hamilton
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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5
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Holmes MJ, Bastos MS, Dey V, Severo V, Wek RC, Sullivan WJ. mRNA cap-binding protein eIF4E1 is a novel regulator of Toxoplasma gondii latency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561274. [PMID: 37873335 PMCID: PMC10592687 DOI: 10.1101/2023.10.09.561274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The protozoan parasite Toxoplasma gondii causes serious opportunistic disease due to its ability to persist in patients as latent tissue cysts. The molecular mechanisms coordinating conversion between proliferative parasites (tachyzoites) and dormant cysts (bradyzoites) are not fully understood. We previously showed that phosphorylation of eIF2α accompanies bradyzoite formation, suggesting that this clinically relevant process involves regulation of mRNA translation. In this study, we investigated the composition and role of eIF4F multi-subunit complexes in translational control. Using CLIPseq, we find that the cap-binding subunit, eIF4E1, localizes to the 5'-end of all tachyzoite mRNAs, many of which show evidence of stemming from heterogenous transcriptional start sites. We further show that eIF4E1 operates as the predominant cap-binding protein in two distinct eIF4F complexes. Using genetic and pharmacological approaches, we found that eIF4E1 deficiency triggers efficient spontaneous formation of bradyzoites without stress induction. Consistent with this result, we also show that stress-induced bradyzoites exhibit reduced eIF4E1 expression. Overall, our findings establish a novel role for eIF4F in translational control required for parasite latency and microbial persistence.
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Affiliation(s)
- Michael J. Holmes
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis IN
| | - Matheus S. Bastos
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis IN
| | - Vishakha Dey
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis IN
| | - Vanessa Severo
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis IN
| | - Ronald C. Wek
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis IN
| | - William J. Sullivan
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis IN
- Department of Microbiology & Immunology, Indiana University School of Medicine, Indianapolis IN
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6
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Danan CH, Naughton KE, Hayer KE, Vellappan S, McMillan EA, Zhou Y, Matsuda R, Nettleford SK, Katada K, Parham LR, Ma X, Chowdhury A, Wilkins BJ, Shah P, Weitzman MD, Hamilton KE. Intestinal transit amplifying cells require METTL3 for growth factor signaling, KRAS expression, and cell survival. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.06.535853. [PMID: 37066277 PMCID: PMC10104132 DOI: 10.1101/2023.04.06.535853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Intestinal epithelial transit amplifying cells are essential stem progenitors required for intestinal homeostasis, but their rapid proliferation renders them vulnerable to DNA damage from radiation and chemotherapy. Despite their critical roles in intestinal homeostasis and disease, few studies have described genes that are essential to transit amplifying cell function. We report that the RNA methyltransferase, METTL3, is required for survival of transit amplifying cells in the murine small intestine. Transit amplifying cell death after METTL3 deletion was associated with crypt and villus atrophy, loss of absorptive enterocytes, and uniform wasting and death in METTL3-depleted mice. Ribosome profiling and sequencing of methylated RNAs in enteroids and in vivo demonstrated decreased translation of hundreds of unique methylated transcripts after METTL3 deletion, particularly transcripts involved in growth factor signal transduction such as Kras. Further investigation confirmed a novel relationship between METTL3 and Kras methylation and protein levels in vivo. Our study identifies METTL3 as an essential factor supporting the homeostasis of small intestinal tissue via direct maintenance of transit amplifying cell survival. We highlight the crucial role of RNA modifications in regulating growth factor signaling in the intestine, with important implications for both homeostatic tissue renewal and epithelial regeneration.
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Affiliation(s)
- Charles H. Danan
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Medical Scientist Training Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Kaitlyn E. Naughton
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katharina E. Hayer
- Department of Biomedical and Health Informatics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Division of Protective Immunity, Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine; University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Sangeevan Vellappan
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ, 08854, USA
- Department of Genetics, Rutgers University, Piscataway, NJ, 08854, USA
- Human Genetics Institute of New Jersey, Piscataway, NJ, 08854, USA
| | - Emily A. McMillan
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yusen Zhou
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Biomedical and Health Informatics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Rina Matsuda
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Shaneice K. Nettleford
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Kay Katada
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Louis R. Parham
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Xianghui Ma
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Afrah Chowdhury
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Benjamin J. Wilkins
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine; University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Premal Shah
- Department of Genetics, Rutgers University, Piscataway, NJ, 08854, USA
- Human Genetics Institute of New Jersey, Piscataway, NJ, 08854, USA
| | - Matthew D. Weitzman
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Protective Immunity, Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine; University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Kathryn E. Hamilton
- Division of Gastroenterology, Hepatology, and Nutrition; Department of Pediatrics; Children’s Hospital of Philadelphia; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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7
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Recent Advances in Our Molecular and Mechanistic Understanding of Misfolded Cellular Proteins in Alzheimer’s Disease (AD) and Prion Disease (PrD). Biomolecules 2022; 12:biom12020166. [PMID: 35204666 PMCID: PMC8961532 DOI: 10.3390/biom12020166] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 12/29/2022] Open
Abstract
Naturally occurring neuron-abundant proteins including amyloid Aβ42 peptide and the microtubule-associated protein tau (MAPT) can, over time and under pathological situations, assume atypical conformations, altering their normal biological structure and function, and causing them to aggregate into insoluble and neurotoxic intracellular inclusions. These misfolded proteins ultimately contribute to the pathogenesis of several progressive, age-related and ultimately lethal human neurodegenerative disorders. The molecular mechanism of this pathological phenomenon of neuronal protein misfolding lends support to the ‘prion hypothesis’, which predicts that the aberrant folding of endogenous natural protein structures into unusual pathogenic isoforms can induce the atypical folding of other similar brain-abundant proteins, underscoring the age-related, progressive nature and potential transmissible and spreading capabilities of the aberrant protein isoforms that drive these invariably fatal neurological syndromes. The abnormal folding and aggregation of host proteins is a consistent feature of both amyloidopathies and tauopathies that encompass a continuous spectrum of brain diseases that include Alzheimer’s disease (AD), prion disorders (PrD) such as scrapie in sheep and goats (Bovidae), experimental prion infection of rodents (Muridae), Creutzfeldt–Jakob disease (CJD) and Gerstmann–Sträussler–Scheinker syndrome (GSS) in humans (Hominidae), and other fatal prion-driven neurological disorders. Because AD patients accumulate both misfolded tau and Aβ peptides, AD may be somewhat unique as the first example of a ‘double prion disorder’. This commentary will examine current research trends in this fascinating research area, with a special emphasis on AD and PrD, and the novel pathological misfolded protein processes common to both intractable neurological disorders.
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