A genome-wide Drosophila RNAi screen identifies DYRK-family kinases as regulators of NFAT.
Precise regulation of the NFAT (nuclear factor of activated T cells) family of transcription factors (NFAT1-4) is essential for vertebrate development and function. In resting cells, NFAT proteins are heavily phosphorylated and reside in the cytoplasm; in cells exposed to stimuli that raise intracellular free Ca2+ levels, they are dephosphorylated by the calmodulin-dependent phosphatase calcineurin and translocate to the nucleus. NFAT dephosphorylation by calcineurin is countered by distinct NFAT kinases, among them casein kinase 1 (CK1) and glycogen synthase kinase 3 (GSK3). Here we have used a genome-wide RNA interference (RNAi) screen in Drosophila to identify additional regulators of the signalling pathway leading from Ca2+-calcineurin to NFAT. This screen was successful because the pathways regulating NFAT subcellular localization (Ca2+ influx, Ca2+-calmodulin-calcineurin signalling and NFAT kinases) are conserved across species, even though Ca2+-regulated NFAT proteins are not themselves represented in invertebrates. Using the screen, we have identified DYRKs (dual-specificity tyrosine-phosphorylation regulated kinases) as novel regulators of NFAT. DYRK1A and DYRK2 counter calcineurin-mediated dephosphorylation of NFAT1 by directly phosphorylating the conserved serine-proline repeat 3 (SP-3) motif of the NFAT regulatory domain, thus priming further phosphorylation of the SP-2 and serine-rich region 1 (SRR-1) motifs by GSK3 and CK1, respectively. Thus, genetic screening in Drosophila can be successfully applied to cross evolutionary boundaries and identify new regulators of a transcription factor that is expressed only in vertebrates.
Gwack
Yousang
Y
The CBR Institute for Biomedical Research and the Departments of Pathology, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
Sharma
Sonia
S
Nardone
Julie
J
Tanasa
Bogdan
B
Iuga
Alina
A
Srikanth
Sonal
S
Okamura
Heidi
H
Bolton
Diana
D
Feske
Stefan
S
Hogan
Patrick G
PG
Rao
Anjana
A
D000818:Animals; D047389:Casein Kinase I / Q000378:metabolism; D004330:Drosophila / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D049750:Genome, Insect / Q000235:genetics*; D023281:Genomics; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D007376:Interleukin-2 / Q000235:genetics; D050778:NFATC Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000145:classification* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000145:classification* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D014158:Transcription, Genetic / Q000235:genetics; D000097603:Dyrk Kinases
D047389:Casein Kinase I; D038362:Glycogen Synthase Kinase 3; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D000097603:Dyrk Kinases