AMP-Activated Protein Kinase Regulates the Cell Surface Proteome and Integrin Membrane Traffic

Abstract

The cell surface proteome controls numerous cellular functions including cell migration and adhesion, intercellular communication and nutrient uptake. Cell surface proteins are controlled by acute changes in protein abundance at the plasma membrane through regulation of endocytosis and recycling (endomembrane traffic). Many cellular signals regulate endomembrane traffic, including metabolic signaling; however, the extent to which the cell surface proteome is controlled by acute regulation of endomembrane traffic under various conditions remains incompletely understood. AMP-activated protein kinase (AMPK) is a key metabolic sensor that is activated upon reduced cellular energy availability. AMPK activation alters the endomembrane traffic of a few specific proteins, as part of an adaptive response to increase energy intake and reduce energy expenditure. How increased AMPK activity during energy stress may globally regulate the cell surface proteome is not well understood. To study how AMPK may regulate the cell surface proteome, we used cell-impermeable biotinylation to selectively purify cell surface proteins under various conditions. Using ESI-MS/MS, we found that acute (90 min) treatment with the AMPK activator A-769662 elicits broad control of the cell surface abundance of diverse proteins. In particular, A-769662 treatment depleted from the cell surface proteins with functions in cell migration and adhesion. To complement our mass spectrometry results, we used other methods to show that A-769662 treatment results in impaired cell migration. Further, A-769662 treatment reduced the cell surface abundance of β1-integrin, a key cell migration protein, and AMPK gene silencing prevented this effect. While the control of the cell surface abundance of various proteins by A-769662 treatment was broad, it was also selective, as this treatment did not change the cell surface abundance of the transferrin receptor. Hence, the cell surface proteome is subject to acute regulation by treatment with A-769662, at least some of which is mediated by the metabolic sensor AMPK.

Selective regulation of clathrin-mediated epidermal growth factor receptor signaling and endocytosis by phospholipase C and calcium

“…, 2012) by manually delineating a region of interest corresponding to the cell outline, followed by measurement of the mean pixel intensity within this region (Ross et al. , 2015) for each of the TIRF-M and epifluorescence channels for each cell.…”

Energetic adaptations: Metabolic control of endocytic membrane traffic

“…While AMPK has many targets that regulate a broad range of cellular processes, some are proteins that either modulate or undergo endocytic traffic. We previously uncovered that AMPK activation leads to broad yet specific changes to the cell surface proteome in epithelial cells, suggesting that AMPK may broadly control endocytic membrane traffic (Figure ). Indeed, AMPK regulates specific activities like glucose transport and broader processes like cell migration, as we examine next.…”

Vaccinium angustifolium (lowbush blueberry) leaf extract increases extravillous trophoblast cell migration and invasion in vitro

“…Although the importance of AMPK in trophoblast cell differentiation and in placental abnormalities has recently become evident (Carey et al, ), the role of AMPK in trophoblast cell migration and invasion has yet to be examined. Nevertheless, AMPK cell signalling is known to alter cell migration and invasion in other cell types, including endothelial cells and tumour cells (Kaiser et al, ; Vincent et al, ), and also regulates the expression of cell surface proteins involved in cell motility (Ross et al, ). Furthermore, a study using chemical genetic screening of whole cells revealed that many AMPK substrates have known roles in cell motility, adhesion, and invasion (Schaffer et al, ).…”

“…Although the effects of V . angustifolium on AMPK signalling in placental trophoblast cells have not yet been studied, it is important to note that AMPK has been identified as a key regulator of cell migration, invasion, and adhesion in other cell types (Kaiser, Friedrich, Chavakis, Böhm, & Friedrich, ; Ross et al, ; Schaffer et al, ; Vincent et al, ). It was therefore hypothesized that V .…”