Interferon signaling is dependent on specific tyrosines located within the intracellular domain of IFNAR2c. Expression of IFNAR2c tyrosine mutants in U5A cells.
Type I interferons (IFNs) are cytokines that play a central role in mediating antiviral, antiproliferative, and immunomodulatory activities in virtually all cells. These activities are entirely dependent on the interaction of IFNs with their particular cell surface receptor. In this report, we identify two specific tyrosine residues located within the cytoplasmic domain of IFNAR2c that are obligatory for IFN-dependent signaling. Various IFNAR2c tyrosine mutants were expressed in a human lung fibroscarcoma cell line lacking IFNAR2c (U5A). Stable clones expressing these mutants were analyzed for their ability to induce STAT1 and STAT2 activation, ISGF3 transcriptional complex formation, gene expression, and cell growth regulation in response to stimulation with type I IFNs. The replacement of all seven cytoplasmic tyrosine residues of IFNAR2c with phenylalanine resulted in a receptor unable to respond to IFN stimulation. Substitution of single tyrosines at amino acid residue 269, 316, 318, 337, or 512 with phenylalanine had no effect on IFN-dependent signaling, suggesting that no single tyrosine is essential for IFN receptor-mediated signaling. In addition, IFNAR2c retaining five proximal tyrosines residues (269, 306, 316, 318, and 337) or either two distal tyrosine residues (411 or 512) continued to be responsive to IFN stimulation. Surprisingly, the presence of only a single tyrosine at either position 337 or 512 was sufficient to restore a complete IFN response. These results indicate that IFN-dependent signaling proceeds through the redundant usage of two tyrosine residues in the cytoplasmic domain of IFNAR2c.
Wagner
T Charis
TC
Berlex Biosciences Inc., Richmond, California 94804, USA.
Velichko
Sharlene
S
Vogel
David
D
Rani
M R Sandhya
MR
Leung
Stewart
S
Ransohoff
Richard M
RM
Stark
George R
GR
Perez
H Daniel
HD
Croze
Ed
E
D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007370:Interferon Type I / Q000378:metabolism* / Q000494:pharmacology; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D008565:Membrane Proteins; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000737:chemistry / Q000378:metabolism*; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*
D004268:DNA-Binding Proteins; C494227:IRF9 protein, human; D007370:Interferon Type I; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D008565:Membrane Proteins; D017471:Receptors, Interferon; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D053633:Receptor, Interferon alpha-beta; D014443:Tyrosine