ELAV proteins are implicated in regulating the stability and translation of cytokine and growth regulatory mRNAs such as GM-CSF, IL-2, c-myc, c-fos and GLUT1 by binding to their AU-rich 3′UTRs. The tissue-specific ELAV protein HuB (aka. Hel-N1) is predominantly cytoplasmic and has been shown to stabilize GLUT1 and c-myc mRNAs and to increase their translation following ectopic expression in 3T3-L1 cells. We report that the most widely expressed mouse ELAV protein, mHuA, is predominately nuclear in cultured NIH-3T3 cells, but is localized in the cytoplasm during early G1 of the cell cycle. Therefore, much like the primarily cytoplasmic HuB, HuA becomes temporally localized in the cytoplasm where it can potentially regulate the stability or translation of bound mRNAs. Moreover, we report that stimulation of mouse spleen cells using either mitogenic or sub-mitogenic levels of anti-CD3/CD28 resulted in a dramatic increase in the level of HuA. Upregulation of HuA corresponds to previously documented increases in cytokine expression which are due to increased mRNA stability following T cell activation. Consistent with these findings, HuA was down regulated in quiescent cells and upregulated in 3T3 cells following serum stimulation. The increase of murine HuA during the cell cycle closely resembles that of cyclin B1 which peaks in G2/M. Together with our earlier studies, these data indicate that mammalian ELAV proteins function during cell growth and differentiation due in part to their effects on posttranscriptional stability and translation of multiple growth regulatory mRNAs. This supports the hypothesis that ELAV proteins can function as transacting factors which affect a default pathway of mRNA degradation involved in the expression of growth regulatory proteins.

REFERENCES

Antic
D.
,
Keene
J. D.
(
1997
).
Embryonic lethal abnormal visual RNA-binding proteins involved in growth, differentiation, and posttranscriptional gene expression.
Am. J. Hum. Genet
61
,
273
278
Antic
D.
,
Keene
J. D.
(
1998
).
Messenger ribonucleoprotein complexes containing human ELAV proteins: interactions with cytoskeleton and translational apparatus.
J. Cell Sci
111
,
183
197
Biamonti
G.
,
Bassi
M. T.
,
Cartegni
L.
,
Mechta
F.
,
Buvoli
M.
,
Cobianchi
F.
,
Riva
S.
(
1993
).
Human hnRNP protein A1 gene expression. Structural and functional characterization of the promoter.
J. Mol. Biol
230
,
77
89
Bogerd
H. P.
,
Fridell
R. A.
,
Benson
R. E.
,
Hua
J.
,
Cullen
B. R.
(
1996
).
Protein sequence requirements for function of the human T-cell leukemia virus type 1 Rex nuclear export signal delineated by a novel in vivo randomization-selection assay.
Mol. Cell. Biol
16
,
4207
4214
Bohjanen
P. R.
,
Petryniak
B.
,
June
C. H.
,
Thompson
C. B.
,
Lindsten
T.
(
1991
).
An inducible cytoplasmic factor (AU-B) binds selectively to AUUUA multimers in the 3untranslated region of lymphokine mRNA.
Mol. Cell. Biol
11
,
3288
3295
Bohjanen
P. R.
,
Petryniak
B.
,
June
C. H.
,
Thompson
C. B.
,
Lindsten
T.
(
1992
).
AU RNA-binding factors differ in their binding specificities and affinities.
J. Biol. Chem
267
,
6302
6309
DeGregori
J.
,
Leone
G.
,
Ohtani
K.
,
Miron
A.
,
Nevins
J. R.
(
1995
).
E2F-1 accumulation bypasses a G1arrest resulting from the inhibition of G1cyclin-dependent kinase activity.
Genes Dev
9
,
2873
2887
Fan
X. C.
,
Steitz
J. A.
(
1998
).
Overexpression of HuR, a nuclear-cytoplasmic shuttling protein, increases the in vivo stability of ARE-containing mRNAs.
EMBO J
17
,
3448
3460
Fischer
U.
,
Meyer
S.
,
Teufel
M.
,
Heckel
C.
,
Luhrmann
R.
,
Rautmann
G.
(
1994
).
Evidence that HIV-1 Rev directly promotes the nuclear export of unspliced RNA.
EMBO J
13
,
4105
4112
Gao
F. B.
,
Carson
C.
,
Levine
T.
,
Keene
J. D.
(
1994
).
Selection of a subset of mRNAs from combinatorial 3untranslated region libraries using neuronal RNA-binding protein Hel-N1.
Proc. Nat. Acad. Sci. USA
91
,
11207
11211
Gao
F. B.
,
Keene
J. D.
(
1996
).
Hel-N1/Hel-N2 proteins are bound to poly(A)+mRNA in granular RNP structures and are implicated in neuronal differentiation.
J. Cell Sci
109
,
579
589
Good
P. J.
(
1995
).
A conserved family of elav-like genes in vertebrates.
Proc. Nat. Acad. Sci. USA
92
,
4557
4561
Hanley-Hyde
J.
,
Mushinski
J. F.
,
Sadofsky
M.
,
Huppi
K.
,
Krall
M.
,
Kozak
C. A.
,
Mock
B.
(
1992
).
Expression of murine cyclin B1 mRNAs and genetic mapping of related genomic sequences.
Genomics
13
,
1018
1030
Jain
R. G.
,
Andrews
L. G.
,
McGowan
K. M.
,
Pekala
P. H.
,
Keene
J. D.
(
1997
).
Ectopic expression of Hel-N1, an RNA-binding protein, increases glucose transporter (GLUT-1) expression in 3T3-L1 adipocytes.
Mol. Cell. Biol
17
,
954
962
Jans
D. A.
(
1995
).
The regulation of protein transport to the nucleus by phosphorylation.
Biochem. J
311
,
705
716
Jong
A. Y.
,
Wang
B.
,
Zhang
S. Q.
(
1995
).
Pulsed field gel electrophoresis labeling method to study the pattern of Saccharomyces cerevisiae chromosomal DNA synthesis during the G1/S phase of the cell cycle.
Anal. Biochem
227
,
32
39
June
C. H.
,
Ledbetter
J. A.
,
Gillespie
M.
,
Lindsten
T.
,
Thompson
C. B.
(
1987
).
T-cell proliferation involving the CD28 pathway is associated with cyclosporine-resistant interleukin 2 gene expression.
Mol. Cell. Biol
7
,
4472
4481
Katz
D. A.
,
Theodorakis
N. G.
,
Cleveland
D. W.
,
Lindsten
T.
,
Thompson
C. B.
(
1994
).
AU-A, an RNA-binding activity distinct from hnRNP A1, is selective for AUUUA repeats and shuttles between the nucleus and the cytoplasm.
Nucl. Acids Res
22
,
238
246
King
P. H.
,
Levine
T. D.
,
Fremeau
R. T.
Jr.
,
Keene
J. D.
(
1994
).
Mammalian homologs of Drosophila ELAV localized to a neuronal subset can bind in vitro to the 3UTR of mRNA encoding the Id transcriptional repressor.
J. Neurosci
14
,
1943
1952
Lee
D.
,
Staats
H. F.
,
Sundy
J. D.
,
Patel
D.
,
Sempowski
G. D.
,
Scearce
R. M.
,
Jones
D. M.
,
Haynes
B. F.
(
1998
).
Immunologic characterization of CD7-deficient mice.
J. Immunol.
,
160
,
5749
5756
Levine
T. D.
,
Gao
F.
,
King
P. H.
,
Andrews
L. G.
,
Keene
J. D.
(
1993
).
Hel-N1: an autoimmune RNA-binding protein with specificity for 3uridylate-rich untranslated regions of growth factor mRNAs.
Mol. Cell. Biol
13
,
3494
3504
Levy
N. S.
,
Chung
S.
,
Furneaux
H.
,
Levy
A. P.
(
1998
).
Hypoxic stabilization of vascular endothelial growth factor mRNA by the RNA-binding protein HuR.
J. Biol. Chem
273
,
6417
6423
Lindsten
T.
,
June
C. H.
,
Ledbetter
J. A.
,
Stella
G.
,
Thompson
C. B.
(
1989
).
Regulation of lymphokine messenger RNA stability by a surface-mediated T cell activation pathway.
Science
244
,
339
343
Ma
W. J.
,
Cheng
S.
,
Campbell
C.
,
Wright
A.
,
Furneaux
H.
(
1996
).
Cloning and characterization of HuR, a ubiquitously expressed Elav-like protein.
J. Biol. Chem
271
,
8144
8151
Maity
A.
,
McKenna
W. G.
,
Muschel
R. J.
(
1995
).
Evidence for post-transcriptional regulation of cyclin B1 mRNA in the cell cycle and following irradiation in HeLa cells.
EMBO J
14
,
603
609
Maity
A.
,
McKenna
W. G.
,
Muschel
R. J.
(
1997
).
Cyclin A message stability varies with cell cycle.
Cell Growth Differ
8
,
311
318
Myer
V. E.
,
Fan
X. C.
,
Steitz
J. A.
(
1997
).
Identification of HuR as a protein implicated in AUUUA-mediated mRNA decay.
EMBO J
16
,
2130
2139
Noel
P. J.
,
Boise
L. H.
,
Green
J. M.
,
Thompson
C. B.
(
1996
).
CD28 costimulation prevents cell death during primary T cell activation.
J. Immunol
157
,
636
642
Okano
H. J.
,
Darnell
R. B.
(
1997
).
A hierarchy of Hu RNA binding proteins in developing and adult neurons.
J. Neurosci
17
,
3024
3037
Peng
S.-Y. S.
,
Chen
C.-Y. A.
,
Xu
N.
,
Shyu
A.-B.
(
1998
).
RNA stabilization by the AU-rich element binding protein, HuR an ELAV protein.
EMBO J
17
,
3461
3470
Pinol-Roma
S.
,
Dreyfuss
G.
(
1991
).
Transcription-dependent and transcription-independent nuclear transport of hnRNP proteins.
Science
253
,
312
314
Pinol-Roma
S.
,
Dreyfuss
G.
(
1992
).
Shuttling of pre-mRNA binding proteins between nucleus and cytoplasm.
Nature
355
,
730
732
Query
C.
,
Bentley
R. C.
,
Keene
J. D.
(
1989
).
A common RNA recognition motif identified within a defined U1 RNA binding domain of the 70K U1 snRNP protein.
Cell
57
,
89
101
Ravnik
S. E.
,
Wolgemuth
D. J.
(
1996
).
The developmentally restricted pattern of expression in the male germ line of a murine cyclin A, cyclin A2, suggests roles in both mitotic and meiotic cell cycles.
Dev. Biol
173
,
69
78
Robinow
S.
,
Campos
A. R.
,
Yao
K. M.
,
White
K.
(
1988
).
The elav gene product of Drosophila, required in neurons, has three RNP consensus motifs.
Science
242
,
1570
1572
Robinow
S.
,
White
K.
(
1991
).
Characterization and spatial distribution of the ELAV protein during Drosophila melanogaster development.
J. Neurobiol
22
,
443
461
Romac
J. M.
,
Graff
D. H.
,
Keene
J. D.
(
1994
).
The U1 small nuclear ribonucleoprotein (snRNP) 70K protein is transported independently of U1 snRNP particles via a nuclear localization signal in the RNA-binding domain.
Mol. Cell. Biol
14
,
4662
4670
Szabo
A.
,
Dalmau
J.
,
Manley
G.
,
Rosenfeld
M.
,
Wong
E.
,
Henson
J.
,
Posner
J. B.
,
Furneaux
H. M.
(
1991
).
HuD, a paraneoplastic encephalomyelitis antigen, contains RNA-binding domains and is homologous to elav and sex-lethal.
Cell
67
,
629
639
Thompson
C. B.
,
Lindsten
T.
,
Ledbetter
J. A.
,
Kunkel
S. L.
,
Young
H. A.
,
Emerson
S. G.
,
Leiden
J. M.
,
June
C. H.
(
1989
).
CD28 activation pathway regulates the production of multiple T-cell-derived lymphokines/cytokines.
Proc. Nat. Acad. Sci. USA
86
,
1333
1337
Umlauf
S. W.
,
Beverly
B.
,
Lantz
O.
,
Schwartz
R. H.
(
1995
).
Regulation of interleukin 2 gene expression by CD28 costimulation in mouse T-cell clones: both nuclear and cytoplasmic RNAs are regulated with complex kinetics.
Mol. Cell. Biol
15
,
3197
3205
Vakalopoulou
E.
,
Schaack
J.
,
Shenk
T.
(
1991
).
A 32-kilodalton protein binds to AU-rich domains in the 3untranslated regions of rapidly degraded mRNAs.
Mol. Cell. Biol
11
,
3355
3364
Wakamatsu
Y.
,
Weston
J. A.
(
1997
).
Sequential expression and role of Hu RNA-binding proteins during neurogenesis.
Development
124
,
3449
3460
Weinberg
R. A.
,
Penman
S.
(
1968
).
Small molecular weight monodisperse nuclear RNA.
J. Mol. Biol
38
,
289
304
Wen
W.
,
Meinkoth
J. L.
,
Tsien
R. Y.
,
Taylor
S. S.
(
1995
).
Identification of a signal for rapid export of proteins from the nucleus.
Cell
82
,
463
473
Wu
L.
,
Good
P. J.
,
Richter
J. D.
(
1997
).
The 36-Kilodalton Embryonic-Type Cytoplasmic Polyadenylation Element-Binding Protein in Xenopus laevis is ElrA, a Member of the ELAV Family of RNA-Binding Proteins.
Mol. Cell. Biol
17
,
6402
6409
Zinszner
H.
,
Sok
J.
,
Immanuel
D.
,
Yin
Y.
,
Ron
D.
(
1997
).
TLS (FUS) binds RNA in vivo and engages in nucleo-cytoplasmic shuttling.
J. Cell Sci
110
,
1741
1750
This content is only available via PDF.