Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo

Constanze Kaiser, Elena Y. Dobrikova, Shelton Bradrick, Mayya Shveygert, James T. Herbert, Matthias Gromeier

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Protein synthesis is tightly controlled by assembly of an intricate ribonucleoprotein complex at the m7GTP-cap on eukaryotic mRNAs. Ensuing linear scanning of the 5′ untranslated region (UTR) is believed to transfer the preinitiation complex to the initiation codon. Eukaryotic mRNAs are characterized by significant 5′ UTR heterogeneity, raising the possibility of differential control of translation initiation rate at individual mRNAs. Curiously, many mRNAs with unconventional, highly structured 5′ UTRs encode proteins with central biological roles in growth control, metabolism, or stress response. The 5′ UTRs of such mRNAs may influence protein synthesis rate in multiple ways, but most significantly they have been implicated in mediating alternative means of translation initiation. Cap-independent initiation bypasses strict control over the formation of initiation intermediates at the m7GTP cap. However, the molecular mechanisms that favor alternative means of ribosome recruitment are not understood. Here we provide evidence that eukaryotic initiation factor (eIF) 4G controls cap-independent translation initiation at the c-myc and vascular endothelial growth factor (VEGF) 5′ UTRs in vivo. Cap-independent translation was investigated in tetracycline-inducible cell lines expressing either full-length eIF4G or a C-terminal fragment (Ct) lacking interaction with eIF4E and poly(A) binding protein. Expression of Ct, but not intact eIF4G, potently stimulated cap-independent initiation at the c-myc/VEGF 5′ UTRs. In vitro RNA-binding assays suggest that stimulation of cap-independent translation initiation by Ct is due to direct association with the c-myc/VEGF 5′ UTR, enabling 43S preinitiation complex recruitment. Our work demonstrates that variant translation initiation factors enable unconventional translation initiation at mRNA subsets with distinct structural features.

Original languageEnglish (US)
Pages (from-to)2170-2182
Number of pages13
JournalRNA
Volume14
Issue number10
DOIs
StatePublished - Oct 2008
Externally publishedYes

Fingerprint

Eukaryotic Initiation Factor-4G
5' Untranslated Regions
Messenger RNA
Vascular Endothelial Growth Factor A
Poly(A)-Binding Proteins
Peptide Initiation Factors
Proteins
Ribonucleoproteins
Initiator Codon
Tetracycline
Ribosomes
RNA
Cell Line

Keywords

  • C-myc
  • eIF4E
  • eIF4G
  • PABP
  • Translation
  • VEGF

ASJC Scopus subject areas

  • Molecular Biology

Cite this

Kaiser, C., Dobrikova, E. Y., Bradrick, S., Shveygert, M., Herbert, J. T., & Gromeier, M. (2008). Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo. RNA, 14(10), 2170-2182. https://doi.org/10.1261/rna.1171808

Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo. / Kaiser, Constanze; Dobrikova, Elena Y.; Bradrick, Shelton; Shveygert, Mayya; Herbert, James T.; Gromeier, Matthias.

In: RNA, Vol. 14, No. 10, 10.2008, p. 2170-2182.

Research output: Contribution to journalArticle

Kaiser, C, Dobrikova, EY, Bradrick, S, Shveygert, M, Herbert, JT & Gromeier, M 2008, 'Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo', RNA, vol. 14, no. 10, pp. 2170-2182. https://doi.org/10.1261/rna.1171808
Kaiser C, Dobrikova EY, Bradrick S, Shveygert M, Herbert JT, Gromeier M. Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo. RNA. 2008 Oct;14(10):2170-2182. https://doi.org/10.1261/rna.1171808
Kaiser, Constanze ; Dobrikova, Elena Y. ; Bradrick, Shelton ; Shveygert, Mayya ; Herbert, James T. ; Gromeier, Matthias. / Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo. In: RNA. 2008 ; Vol. 14, No. 10. pp. 2170-2182.
@article{155d4b000b124285b67e2754b68317b4,
title = "Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo",
abstract = "Protein synthesis is tightly controlled by assembly of an intricate ribonucleoprotein complex at the m7GTP-cap on eukaryotic mRNAs. Ensuing linear scanning of the 5′ untranslated region (UTR) is believed to transfer the preinitiation complex to the initiation codon. Eukaryotic mRNAs are characterized by significant 5′ UTR heterogeneity, raising the possibility of differential control of translation initiation rate at individual mRNAs. Curiously, many mRNAs with unconventional, highly structured 5′ UTRs encode proteins with central biological roles in growth control, metabolism, or stress response. The 5′ UTRs of such mRNAs may influence protein synthesis rate in multiple ways, but most significantly they have been implicated in mediating alternative means of translation initiation. Cap-independent initiation bypasses strict control over the formation of initiation intermediates at the m7GTP cap. However, the molecular mechanisms that favor alternative means of ribosome recruitment are not understood. Here we provide evidence that eukaryotic initiation factor (eIF) 4G controls cap-independent translation initiation at the c-myc and vascular endothelial growth factor (VEGF) 5′ UTRs in vivo. Cap-independent translation was investigated in tetracycline-inducible cell lines expressing either full-length eIF4G or a C-terminal fragment (Ct) lacking interaction with eIF4E and poly(A) binding protein. Expression of Ct, but not intact eIF4G, potently stimulated cap-independent initiation at the c-myc/VEGF 5′ UTRs. In vitro RNA-binding assays suggest that stimulation of cap-independent translation initiation by Ct is due to direct association with the c-myc/VEGF 5′ UTR, enabling 43S preinitiation complex recruitment. Our work demonstrates that variant translation initiation factors enable unconventional translation initiation at mRNA subsets with distinct structural features.",
keywords = "C-myc, eIF4E, eIF4G, PABP, Translation, VEGF",
author = "Constanze Kaiser and Dobrikova, {Elena Y.} and Shelton Bradrick and Mayya Shveygert and Herbert, {James T.} and Matthias Gromeier",
year = "2008",
month = "10",
doi = "10.1261/rna.1171808",
language = "English (US)",
volume = "14",
pages = "2170--2182",
journal = "RNA",
issn = "1355-8382",
publisher = "Cold Spring Harbor Laboratory Press",
number = "10",

}

TY - JOUR

T1 - Activation of cap-independent translation by variant eukaryotic initiation factor 4G in vivo

AU - Kaiser, Constanze

AU - Dobrikova, Elena Y.

AU - Bradrick, Shelton

AU - Shveygert, Mayya

AU - Herbert, James T.

AU - Gromeier, Matthias

PY - 2008/10

Y1 - 2008/10

N2 - Protein synthesis is tightly controlled by assembly of an intricate ribonucleoprotein complex at the m7GTP-cap on eukaryotic mRNAs. Ensuing linear scanning of the 5′ untranslated region (UTR) is believed to transfer the preinitiation complex to the initiation codon. Eukaryotic mRNAs are characterized by significant 5′ UTR heterogeneity, raising the possibility of differential control of translation initiation rate at individual mRNAs. Curiously, many mRNAs with unconventional, highly structured 5′ UTRs encode proteins with central biological roles in growth control, metabolism, or stress response. The 5′ UTRs of such mRNAs may influence protein synthesis rate in multiple ways, but most significantly they have been implicated in mediating alternative means of translation initiation. Cap-independent initiation bypasses strict control over the formation of initiation intermediates at the m7GTP cap. However, the molecular mechanisms that favor alternative means of ribosome recruitment are not understood. Here we provide evidence that eukaryotic initiation factor (eIF) 4G controls cap-independent translation initiation at the c-myc and vascular endothelial growth factor (VEGF) 5′ UTRs in vivo. Cap-independent translation was investigated in tetracycline-inducible cell lines expressing either full-length eIF4G or a C-terminal fragment (Ct) lacking interaction with eIF4E and poly(A) binding protein. Expression of Ct, but not intact eIF4G, potently stimulated cap-independent initiation at the c-myc/VEGF 5′ UTRs. In vitro RNA-binding assays suggest that stimulation of cap-independent translation initiation by Ct is due to direct association with the c-myc/VEGF 5′ UTR, enabling 43S preinitiation complex recruitment. Our work demonstrates that variant translation initiation factors enable unconventional translation initiation at mRNA subsets with distinct structural features.

AB - Protein synthesis is tightly controlled by assembly of an intricate ribonucleoprotein complex at the m7GTP-cap on eukaryotic mRNAs. Ensuing linear scanning of the 5′ untranslated region (UTR) is believed to transfer the preinitiation complex to the initiation codon. Eukaryotic mRNAs are characterized by significant 5′ UTR heterogeneity, raising the possibility of differential control of translation initiation rate at individual mRNAs. Curiously, many mRNAs with unconventional, highly structured 5′ UTRs encode proteins with central biological roles in growth control, metabolism, or stress response. The 5′ UTRs of such mRNAs may influence protein synthesis rate in multiple ways, but most significantly they have been implicated in mediating alternative means of translation initiation. Cap-independent initiation bypasses strict control over the formation of initiation intermediates at the m7GTP cap. However, the molecular mechanisms that favor alternative means of ribosome recruitment are not understood. Here we provide evidence that eukaryotic initiation factor (eIF) 4G controls cap-independent translation initiation at the c-myc and vascular endothelial growth factor (VEGF) 5′ UTRs in vivo. Cap-independent translation was investigated in tetracycline-inducible cell lines expressing either full-length eIF4G or a C-terminal fragment (Ct) lacking interaction with eIF4E and poly(A) binding protein. Expression of Ct, but not intact eIF4G, potently stimulated cap-independent initiation at the c-myc/VEGF 5′ UTRs. In vitro RNA-binding assays suggest that stimulation of cap-independent translation initiation by Ct is due to direct association with the c-myc/VEGF 5′ UTR, enabling 43S preinitiation complex recruitment. Our work demonstrates that variant translation initiation factors enable unconventional translation initiation at mRNA subsets with distinct structural features.

KW - C-myc

KW - eIF4E

KW - eIF4G

KW - PABP

KW - Translation

KW - VEGF

UR - http://www.scopus.com/inward/record.url?scp=52949088660&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=52949088660&partnerID=8YFLogxK

U2 - 10.1261/rna.1171808

DO - 10.1261/rna.1171808

M3 - Article

VL - 14

SP - 2170

EP - 2182

JO - RNA

JF - RNA

SN - 1355-8382

IS - 10

ER -