Conditional knockout of the RNA-binding protein HuR in CD4⁺ T cells reveals a gene dosage effect on cytokine production.
The posttranscriptional mechanisms by which RNA binding proteins (RBPs) regulate T-cell differentiation and cytokine production in vivo remain unclear. The RBP HuR binds to labile mRNAs, usually leading to increases in mRNA stability and/or translation. Previous work demonstrated that HuR binds to the mRNAs encoding the Th2 transcription factor trans-acting T-cell-specific transcription factor (GATA-3) and Th2 cytokines interleukin (IL)-4 and IL-13, thereby regulating their expression. By using a novel conditional HuR knockout (KO) mouse in which HuR is deleted in activated T cells, we show that Th2-polarized cells from heterozygous HuR conditional (OX40-Cre HuR(fl/+)) KO mice had decreased steady-state levels of Gata3, Il4 and Il13 mRNAs with little changes at the protein level. Surprisingly, Th2-polarized cells from homozygous HuR conditional (OX40-Cre HuR(fl/fl)) KO mice showed increased Il2, Il4 and Il13 mRNA and protein via different mechanisms. Specifically, Il4 was transcriptionally upregulated in HuR KO T cells, whereas Il2 and Il13 mRNA stabilities increased. Additionally, when using the standard ovalbumin model of allergic airway inflammation, HuR conditional KO mice mounted a robust inflammatory response similar to mice with wild-type HuR levels. These results reveal a complex differential posttranscriptional regulation of cytokines by HuR in which gene dosage plays an important role. These findings may have significant implications in allergies and asthma, as well as autoimmune diseases and infection.
University of Missouri, Columbia, Missouri, United States of America.
Matthew M
MM
Gubin
University of Missouri, Columbia, Missouri, United States of America.
Patsharaporn
P
Techasintana
University of Missouri, Columbia, Missouri, United States of America.
Joseph D
JD
Magee
University of Missouri, Columbia, Missouri, United States of America.
Garrett M
GM
Dahm
University of Missouri, Columbia, Missouri, United States of America.
Robert
R
Calaluce
National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America.
Jennifer L
JL
Martindale
University of Missouri, Columbia, Missouri, United States of America.
Maryln S
MS
Whitney
University of Missouri, Columbia, Missouri, United States of America.
Craig L
CL
Franklin
University of Missouri, Columbia, Missouri, United States of America.
Cindy
C
Besch-Williford
Department of Medicine, Duke University, Durham, North Carolina, United States of America.
John W
JW
Hollingsworth
National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America.
Kotb
K
Abdelmohsen
National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America.
Myriam
M
Gorospe
University of Missouri, Columbia, Missouri, United States of America.
Ulus
U
Atasoy
D000485:Allergens; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002452:Cell Count; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D051959:ELAV Proteins / Q000235:genetics* / Q000378:metabolism; D050990:GATA3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D018628:Gene Dosage; D018345:Mice, Knockout; D010047:Ovalbumin; D011014:Pneumonia / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012130:Respiratory Hypersensitivity / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D013154:Spleen / Q000166:cytology
D000485:Allergens; D016207:Cytokines; D051959:ELAV Proteins; D050990:GATA3 Transcription Factor; C494748:Gata3 protein, mouse; D012333:RNA, Messenger; D010047:Ovalbumin