A quantitative proteomic analysis of cofilin phosphorylation in myeloid cells and its modulation using the LIM kinase inhibitor Pyr1

Abstract

LIM kinases are located at a strategic crossroad, downstream of several signaling pathways and upstream of effectors such as microtubules and the actin cytoskeleton. Cofilin is the only LIM kinases substrate that is well described to date, and its phosphorylation on serine 3 by LIM kinases controls cofilin actin-severing activity. Consequently, LIM kinases inhibition leads to actin cytoskeleton disorganization and blockade of cell motility, which makes this strategy attractive in anticancer treatments. LIMK has also been reported to be involved in pathways that are deregulated in hematologic malignancies, with little information regarding cofilin phosphorylation status. We have used proteomic approaches to investigate quantitatively and in detail the phosphorylation status of cofilin in myeloid tumor cell lines of murine and human origin. Our results show that under standard conditions, only a small fraction (10 to 30% depending on the cell line) of cofilin is phosphorylated (including serine 3 phosphorylation). In addition, after a pharmacological inhibition of LIM kinases, a residual cofilin phosphorylation is observed on serine 3. Interestingly, this 2D gel based proteomic study identified new phosphorylation sites on cofilin, such as threonine 63, tyrosine 82 and serine 108.

How reversible are the effects of silver nanoparticles on macrophages? A proteomic-instructed view

“…For example, the effector spot for cofilin is the median spot. 93 Consistent with what has been described in the literature, we observe mostly modulations on acidic, modified forms of the above-cited proteins.…”

Simultaneous Inhibition of BCR-ABL1 Tyrosine Kinase and PAK1/2 Serine/Threonine Kinase Exerts Synergistic Effect against Chronic Myeloid Leukemia Cells

“…Our results did not support the former mechanism because cofilin, the direct target of LIMK, remained phosphorylated on Serine 3. It has been shown that other kinases than LIMK are able to phosphorylate cofilin at Serine 3 [49,50]. Elevated levels of phosphorylated cofilin at Serine 3 indicate its higher transition to the nucleus.…”

Post-translational S-glutathionylation of cofilin increases actin cycling during cocaine seeking

“…Three-dimensional modeling of cofilin illustrates all four cysteine residues that serve as potential sites for S-glutathionylation, as well as the most widely reported site for serine phosphorylation by LIM kinase (Fig 1A). Additional phosphorylation sites on cofilin, not shown here, include threonine 63, tyrosine 82, and serine 108 [29]. We incubated recombinant cofilin with disulfiram and GSH in vitro to induce its S-glutathionylation (Fig 1B).…”