The role of MPP1/p55 and its palmitoylation in resting state raft organization in HEL cells

Abstract

Here we show the crucial role of MPP1 in lateral membrane ordering/organization in HEL cells (derived from erythroid precursors). Biochemical analyses showed that inhibition of MPP1 palmitoylation or silencing of the MPP1 gene led to a dramatic decrease in the DRM fraction. This was accompanied by a reduction of membrane order as shown by fluorescence-lifetime imaging microscopy (FLIM) analyses. Furthermore, MPP1 knockdown significantly affects the activation of MAP-kinase signaling via raft-dependent RTK (receptor tyrosine kinase) receptors, indicating the importance of MPP1 for lateral membrane organization. In conclusion, palmitoylation of MPP1 appears to be at least one of the mechanisms controlling lateral organization of the erythroid cell membrane. Thus, this study, together with our recent results on erythrocytes, reported elsewhere (Łach et al., J. Biol. Chem., 2012, 287, 18974-18984), points to a new role for MPP1 and presents a novel linkage between membrane raft organization and protein palmitoylation.

Emerging role of chemoprotective agents in the dynamic shaping of plasma membrane organization

“…Interestingly, (+)-catechin dose-dependently reduced membrane rigidity while procyanidin B2 increased rigidity. We subsequently used confocal microscopy to determine if the same effects would occur in live cells (Figures 2E&F), which are generally more refractive to plasma membrane changes[173,174]. Surprisingly, both compounds decreased membrane rigidity in intact cells.…”

PDZ Protein Regulation of G Protein–Coupled Receptor Trafficking and Signaling Pathways

“…MPP3 has been demonstrated to promote the membrane stability of 5-HT 2C R and prevent receptor desensitization (Gavarini et al, 2006). MPP1 has additionally been implicated in membrane organization, raft formation, and receptor tyrosine kinasemediated ERK signaling (Łach et al, 2012;Biernatowska et al, 2013). Thus, it is plausible that MPPs may generally promote the membrane organization of integral proteins, including GPCRs.…”

Membrane Rafts in the Erythrocyte Membrane: A Novel Role of MPP1p55

“…Furthermore, MPP1 -knockdown signifi cantly affects the activation of MAPkinase signaling via raft-dependent tyrosine kinase receptors, indicating the importance of MPP1 for lateral membrane organization (Biernatowska et al 2013 ).…”

“…Moreover, the FLIM experiments using di-4 probe performed on normal and 2-BrP-treated erythrocytes, normal and 2-BrP-treated HEL cells and HEL cells with stably-silenced MPP1 expression, demonstrated signifi cant decrease in membrane-order upon inhibition of palmitoylation, or decrease in cellular MPP1 level (Biernatowska et al 2013 ;Lach et al 2012 ). Similar conclusions were drawn from studies on giant plasma membrane vesicles derived from HEL cells, performed by using several advanced biophysical techniques in parallel (Podkalicka, Grzybek et al -to be published).…”