TY - JOUR

T1 - Hyperosmotic stress strongly potentiates serum response factor (SRF)-dependent transcriptional activity in ehrlich lettré ascites cells through a mechanism involving p38 mitogen-activated protein kinase

AU - Gorbatenko, Andrej

AU - Wiwel, Maria

AU - Klingberg, Henrik

AU - Nielsen, Anni Bech

AU - Kapus, András

AU - Pedersen, Stine Helene Falsig

PY - 2011

Y1 - 2011

N2 - Long-term osmotic stress results in altered gene transcription, however, with the exception of the TonE/TonEBP system, the underlying mechanisms are poorly understood. We previously showed that upon osmotic shrinkage of Ehrlich Lettré Ascites (ELA) fibroblasts, the MEK1-ERK1/2 pathway is transiently inhibited while p38 MAPK is activated, in turn impacting on cell survival (Pedersen et al., 2007, Cell Physiol Biochem 20: 735–750). Here, we show that downstream of these kinases, two transcription factors with major roles in control of cell proliferation and death, serum response factor (SRF) and cAMP response element-binding protein (CREB) are differentially regulated in ELA cells. SRF Ser103 phosphorylation and SRF-dependent transcriptional activity were strongly augmented 5–30¿min and 24¿h, respectively, after hyperosmotic stress (50% increase in extracellular ionic strength), in a p38 MAPK-dependent manner. In contrast, CREB Ser133 was transiently dephosphorylated upon osmotic shrinkage. The ERK1/2 effector ribosomal S kinase (RSK) and the ERK1/2- and p38 MAPK effector mitogen- stress-activated protein kinase 1 (MSK1) both phosphorylate CREB at Ser133. RSK and MSK1 were dephosphorylated within 5¿min of shrinkage. MSK1 phosphorylation recovered within 30¿min in a p38-MAPK-dependent manner. CREB was transiently dephosphorylated after shrinkage in a manner exacerbated by p38 MAPK inhibition or MSK1 knockdown, but unaffected by inhibition of RSK. In conclusion, in ELA cells, hyperosmotic stress activates SRF in a p38 MAPK-dependent manner and transiently inactivates CREB, likely due to MSK1 inactivation. We suggest that these events contribute to shrinkage-induced changes in gene transcription and death/survival balance

AB - Long-term osmotic stress results in altered gene transcription, however, with the exception of the TonE/TonEBP system, the underlying mechanisms are poorly understood. We previously showed that upon osmotic shrinkage of Ehrlich Lettré Ascites (ELA) fibroblasts, the MEK1-ERK1/2 pathway is transiently inhibited while p38 MAPK is activated, in turn impacting on cell survival (Pedersen et al., 2007, Cell Physiol Biochem 20: 735–750). Here, we show that downstream of these kinases, two transcription factors with major roles in control of cell proliferation and death, serum response factor (SRF) and cAMP response element-binding protein (CREB) are differentially regulated in ELA cells. SRF Ser103 phosphorylation and SRF-dependent transcriptional activity were strongly augmented 5–30¿min and 24¿h, respectively, after hyperosmotic stress (50% increase in extracellular ionic strength), in a p38 MAPK-dependent manner. In contrast, CREB Ser133 was transiently dephosphorylated upon osmotic shrinkage. The ERK1/2 effector ribosomal S kinase (RSK) and the ERK1/2- and p38 MAPK effector mitogen- stress-activated protein kinase 1 (MSK1) both phosphorylate CREB at Ser133. RSK and MSK1 were dephosphorylated within 5¿min of shrinkage. MSK1 phosphorylation recovered within 30¿min in a p38-MAPK-dependent manner. CREB was transiently dephosphorylated after shrinkage in a manner exacerbated by p38 MAPK inhibition or MSK1 knockdown, but unaffected by inhibition of RSK. In conclusion, in ELA cells, hyperosmotic stress activates SRF in a p38 MAPK-dependent manner and transiently inactivates CREB, likely due to MSK1 inactivation. We suggest that these events contribute to shrinkage-induced changes in gene transcription and death/survival balance

U2 - 10.1002/jcp.22628

DO - 10.1002/jcp.22628

M3 - Journal article

C2 - 21302281

VL - 226

SP - 2857

EP - 2868

JO - Journal of Cellular Physiology

JF - Journal of Cellular Physiology

SN - 0021-9541

IS - 11

ER -