Inhibition of caspase-9 through phosphorylation at Thr 125 by ERK MAPK.

Article Details

Citation

Allan LA, Morrice N, Brady S, Magee G, Pathak S, Clarke PR

Inhibition of caspase-9 through phosphorylation at Thr 125 by ERK MAPK.

Nat Cell Biol. 2003 Jul;5(7):647-54.

PubMed ID
12792650 [ View in PubMed
]
Abstract

Many pro-apoptotic signals activate caspase-9, an initiator protease that activates caspase-3 and downstream caspases to initiate cellular destruction. However, survival signals can impinge on this pathway and suppress apoptosis. Activation of the Ras-Raf-MEK-ERK mitogen-activated protein kinase (MAPK) pathway is associated with protection of cells from apoptosis and inhibition of caspase-3 activation, although the targets are unknown. Here, we show that the ERK MAPK pathway inhibits caspase-9 activity by direct phosphorylation. In mammalian cell extracts, cytochrome c-induced activation of caspases-9 and -3 requires okadaic-acid-sensitive protein phosphatase activity. The opposing protein kinase activity is overcome by treatment with the broad-specificity kinase inhibitor staurosporine or with inhibitors of MEK1/2. Caspase-9 is phosphorylated at Thr 125, a conserved MAPK consensus site targeted by ERK2 in vitro, in a MEK-dependent manner in cells stimulated with epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA). Phosphorylation at Thr 125 is sufficient to block caspase-9 processing and subsequent caspase-3 activation. We suggest that phosphorylation and inhibition of caspase-9 by ERK promotes cell survival during development and tissue homeostasis. This mechanism may also contribute to tumorigenesis when the ERK MAPK pathway is constitutively activated.

DrugBank Data that Cites this Article

Drugs
Polypeptides
NameUniProt ID
Mitogen-activated protein kinase 1P28482Details
Caspase-9P55211Details