Fast regulation of AP-1 activity through interaction of lamin A/C, ERK1/2, and c-Fos at the nuclear envelope

Abstract

Sequestration of c-Fos at the nuclear envelope (NE) through interaction with A-type lamins suppresses AP-1–dependent transcription. We show here that c-Fos accumulation within the extraction-resistant nuclear fraction (ERNF) and its interaction with lamin A are reduced and enhanced by gain-of and loss-of ERK1/2 activity, respectively. Moreover, hindering ERK1/2-dependent phosphorylation of c-Fos attenuates its release from the ERNF induced by serum and promotes its interaction with lamin A. Accordingly, serum stimulation rapidly releases preexisting c-Fos from the NE via ERK1/2-dependent phosphorylation, leading to a fast activation of AP-1 before de novo c-Fos synthesis. Moreover, lamin A–null cells exhibit increased AP-1 activity and reduced levels of c-Fos phosphorylation. We also find that active ERK1/2 interacts with lamin A and colocalizes with c-Fos and A-type lamins at the NE. Thus, NE-bound ERK1/2 functions as a molecular switch for rapid mitogen-dependent AP-1 activation through phosphorylation-induced release of preexisting c-Fos from its inhibitory interaction with lamin A/C.

The Nuclear Import of Oncoprotein Hepatitis B X-interacting Protein Depends on Interacting with c-Fos and Phosphorylation of Both Proteins in Breast Cancer Cells

“…Plasmids and siRNAs-pCMV-3V-c-Fos, pCMV-4A-c-Fos, and full-length HBXIP constructs were previously described (6,27,28). To identify the corresponding domain that activates c-Fos, full-length HBXIP was divided into 4 fragments, including amino acids 1-82, 83-173, 83-144, and 145-173.…”

“…Immunofluorescence Staining and Confocal MicroscopyCells were grown on acid-treated glass coverslips as described elsewhere (27). Treated cells were fixed with ice-cold 4% paraformaldehyde for 10 min, washed three times with phosphatebuffered saline (PBS), and permeabilized with 0.1% Triton X-100 in PBS for 20 min.…”

“…To confirm the ERK1/2 role in phosphorylation of c-Fos in the event of the nuclear import of HBXIP, we constructed the ERK phosphorylated site mutants vector of c-Fos, containing four amino acid phosphorylation sites at Thr 232 , Thr 325 , Thr 331 , and Ser 374 (termed pCMV-4A-c-Fos) (27), and single mutants (termed T232A, T325A, T331A, and S374A, respectively). To rule out the effect of endogenous c-Fos on the nuclear import of HBXIP, the endogenous c-Fos was silenced by siRNA in MCF-7 cells.…”

The Ras‐ERK pathway: Understanding site‐specific signaling provides hope of new anti‐tumor therapies

“…[75] Interestingly, ERK functions within the nucleus may also be compartmentalized further: ERKs interact with lamin A at the nuclear envelope to promote rapid, mitogen-dependent AP-1 activation, by releasing cFos from its inhibitory interaction with lamin A. [76] A place for a scaffold…”

Dual Specificity Phosphatase 4 Mediates Cardiomyopathy Caused by Lamin A/C (LMNA) Gene Mutation

“…Recent evidence suggests that A-type lamins play a dynamic role in regulating signal transduction, particularly ERK1/2 signaling (1,(3)(4)(5). We previously showed that activated ERK1/2 in hearts of Lmna H222P/H222P mice, a mouse model of LMNA cardiomyopathy, contributes to disease (6 -8).…”