Phosphorylation of Fli1 at Threonine 312 by Protein Kinase C δ Promotes Its Interaction with p300/CREB-Binding Protein-Associated Factor and Subsequent Acetylation in Response to Transforming Growth Factor β

Abstract

Previous studies have shown that transforming growth factor ␤ (TGF-␤)-induced collagen gene expression involves acetylation-dependent dissociation from the human ␣2(I) collagen (COL1A2) promoter of the transcriptional repressor Fli1. The goal of this study was to elucidate the regulatory steps preceding the acetylation of Fli1. We first showed that TGF-␤ induces Fli1 phosphorylation on a threonine residue(s). The major phosphorylation site was localized to threonine 312 located in the DNA binding domain of Fli1. Using several independent approaches, we demonstrated that Fli1 is directly phosphorylated by protein kinase C ␦ (PKC ␦). Additional experiments showed that in response to TGF-␤, PKC ␦ is recruited to the collagen promoter to phosphorylate Fli1 and that this step is a prerequisite for the subsequent interaction of Fli1 with p300/CREBbinding protein-associated factor (PCAF) and an acetylation event. The phosphorylation of endogenous Fli1 preceded its acetylation in response to TGF-␤ stimulation, and the blockade of PKC ␦ abrogated both the phosphorylation and acetylation of Fli1 in dermal fibroblasts. Promoter studies showed that a phosphorylation-deficient mutant of Fli1 exhibited an increased inhibitory effect on the COL1A2 gene, which could not be reversed by the forced expression of PCAF or PKC ␦. These data strongly suggest that the phosphorylationacetylation cascade triggered by PKC ␦ represents the primary mechanism whereby TGF-␤ regulates the transcriptional activity of Fli1 in the context of the collagen promoter.

Abnormal expression of FLI1 protein is an adverse prognostic factor in acute myeloid leukemia

“…We also observed a limited positive correlation between FLI1 levels and protein kinase C ␦, which has been shown to directly phosphorylate FLI1 in response to TGF␤. 45 Our results also showed a positive correlation between FLI1 and the STAT3 protein, which is known to regulate the FLI1 promoter. 52 Levels of cyclinD3 and FLI1 were also positively correlated in this dataset, which is consistent with data showing that FLI1 maintains high levels of cyclin D3 and cyclin D2 in erythroblasts, thereby promoting proliferation over differentiation.…”

“…FAK and CREB are interactive partners with ETA factors and CREB has been shown to negatively regulate DNA binding by acetylation of FLI1 in fibroblasts. 45 Functional ETS-binding sites have been shown to regulate transcription of BCLX L , 46 BAX, 47 integrin B3, 48 fibronectin, 49 FAK, 50 and TSC2. 42,51 Except for BCLX L , these were all markedly positively (TSC2 and BAX) or negatively (integrin␤3, fibronectin, and FAK) correlated with FLI1 expression in this study.…”

Krüppel-like factor 4 interacts with p300 to activate mitofusin 2 gene expression induced by all-trans retinoic acid in VSMCs

“…It has been proved that a phosphorylation-acetylation switch regulates STAT1 signaling [33] . Phosphorylation of Fli1 promotes its interaction with p300/ CBP-associated factor and subsequent acetylation in response to TGF-β [34] . Our data showed that KLF4, as a transcription factor regulated by multiple signaling pathways, can be subjected to an unexpected cross-regulation between phosphorylation and acetylation.…”

Transcriptome network-based method to identify genes associated with unruptured intracranial aneurysms

“…Fli1 knock-out mice die during embryogenesis with a loss of vascular integrity leading to cerebral hemorrhage, suggesting that Fli1 is involved in the regulation of genes critical for vascular remodeling (Asano and Trojanowska, 2009). …”