Mechanochemical feedback control of dynamin independent endocytosis modulates membrane tension in adherent cells

Abstract

Plasma membrane tension regulates many key cellular processes. It is modulated by, and can modulate, membrane trafficking. However, the cellular pathway(s) involved in this interplay is poorly understood. Here we find that, among a number of endocytic processes operating simultaneously at the cell surface, a dynamin independent pathway, the CLIC/GEEC (CG) pathway, is rapidly and specifically upregulated upon a sudden reduction of tension. Moreover, inhibition (activation) of the CG pathway results in lower (higher) membrane tension. However, alteration in membrane tension does not directly modulate CG endocytosis. This requires vinculin, a mechano-transducer recruited to focal adhesion in adherent cells. Vinculin acts by controlling the levels of a key regulator of the CG pathway, GBF1, at the plasma membrane. Thus, the CG pathway directly regulates membrane tension and is in turn controlled via a mechano-chemical feedback inhibition, potentially leading to homeostatic regulation of membrane tension in adherent cells.

Membrane tension mediated mechanotransduction drives fate choice in embryonic stem cells

“…First, we showed that endocytosis was considerably reduced in cells expressing iEZR_CA ( Fig. 3g, h), suggesting that high membrane tension antagonizes endocytosis, consistent with previous findings in other systems(23) (24). To test whether enhanced endocytosis could overcome the block in differentiation imposed by EZR_CA, we transfected iEZR_CA cells with Rab5a, a master regulator of early endosomes (26).…”

“…We then asked how decreased membrane tension facilitates exit from the ES cell state. We speculated that the facilitation may be through endocytosis, which is a major regulator of signalling events (21) (22) and has been shown to be regulated by membrane tension (23) (24). First, we assessed global endocytosis levels using a fluid phase uptake assay, in which we cultured cells in presence of either fluorescent dextran or a pH-sensitive fluorescent dextran ( Fig.…”

An acute decrease in plasma membrane tension induces macropinocytosis via PLD2 activation

“…Several endocytic pathways have been reported to be induced by a sudden decrease of PM tension, including the CLIC/GEEC pathway, vacuole-like dilation and GRAF-1-dependent endocytosis (Holst et al, 2017;Kosmalska et al, 2015;Thottacherry et al, 2018). Despite the similarity in morphology, the dependency on PLD activity and the enrichment of actin found in macropinocytosis induced by decreased PM tension in myoblasts is distinct from the ATP-and actin-independent vacuole-like dilation found in mouse embryonic fibroblasts upon cell volume decrease (Kosmalska et al, 2015).…”

Endosomal spatio-temporal modulation of the cortical RhoA zone conditions epithelial cell organization

“…Control of membrane tension appears critical for the progression through this P2 phase (Gauthier et al, 2012), and would be ensured by coordinated regulation of membrane trafficking events and myosin-II contractility (Apodaca, 2002; Gauthier et al, 2011; Pontes et al, 2017). For instance, inhibition of myosin-IIA activity keeps fibroblasts blocked in P2 phase (Cai et al, 2010), and reduction of membrane tension triggers endocytosis pathway (Thottacherry et al, 2018). Our findings show that EpCAM-KD cells fail to complete P2 phase and display isotropic and, to some extent, C-shapes (Figure 1d-i; Supplementary Figure 1), as do myosin-IIA mutant fibroblasts (Cai et al, 2010).…”