α-Synuclein plasma membrane localization correlates with cellular phosphatidylinositol polyphosphate levels
Authors: Cédric Eichmann
Reeba Susan Jacob
Alessandro Dema
Philipp Selenko
Davide Mercadante
Journal: eLife (2021)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: A2780; HeLa; SH-SY5Y; SK-MEL-2; human cell lines
Affiliations: Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.

Abstract:  The Parkinson's disease protein α-synuclein (αSyn) promotes membrane fusion and fission by interacting with various negatively charged phospholipids. Despite postulated roles in endocytosis and exocytosis, plasma membrane (PM) interactions of αSyn are poorly understood. Here, we show that phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3), two highly acidic components of inner PM leaflets, mediate PM localization of endogenous pools of αSyn in A2780, HeLa, SK-MEL-2, and differentiated and undifferentiated neuronal SH-SY5Y cells. We demonstrate that αSyn binds to reconstituted PIP2 membranes in a helical conformation in vitro and that PIP2 synthesizing kinases and hydrolyzing phosphatases reversibly redistribute αSyn in cells. We further delineate that αSyn-PM targeting follows phosphoinositide-3 kinase (PI3K)-dependent changes of cellular PIP2 and PIP3 levels, which collectively suggests that phosphatidylinositol polyphosphates contribute to αSyn's function(s) at the plasma membrane. 

Retracted: No

PubPeer comments:
 *[left]* Figure 2 from [Tang et al (2020)] .  Fluorescence microscopy using acridine orange ethidium bromide (AO EB) staining used to evaluate the apoptotic effects of herbal extract of Artemisia maritima in human NCI-H1437 lung cancer cells. The percentage of apoptotic cells (yellow and orange fluorescence) increased concentration-dependently . *[right]* Figure 2 from [Liu et al (2020)] .  AO EB staining showing the induction of apoptosis in LNCaP prostate cancer cells at indicated concentrations of auraptenol. The Figure shows green fluorescence in untreated cells and orange yellow fluorescence in auraptenol-treated cells indicating onset of apoptosis . ![file] Two pairs of panels overlap. Inquiring minds are wondering how this happened. , 
 Figs 4 and 6 from [Tang et al (2020)] .  Assessment of the effect of herbal extract of Artemisia maritima on the expression levels of Bax and Bcl-2 (apoptosis-related proteins) using western blot method. Increasing doses of Artemisia maritima extract led to decrease in the expression of Bcl-2 (anti-apoptotic) and to increase of Bax ...  Assessment of the effect of herbal extract of Artemisia maritima on the expression levels of cyclin-B1 (cell cycle-related protein) employing western blot assay. Artemisia maritima could inhibit cyclin B1 protein expression which is a key factor in cell cycle regulation . ![file] For comparison: *[left]* Figure 5 from [Meng, Tang Qiu (2019)] .  Effect of Lactucopicrin on the expression of Bax and Bcl-2 expression in Saos-2 cells as indicated by western blot analysis . *[right]* Figure 4 from [Zhang et al (2020)] .  Baicalein induced activation of caspase and mitochondrial mediated apoptosis-related proteins in CAPAN-2 pancreatic cancer cells. After treatment with Baicalein (10, 20 and 40 u03bcM) for 24h, cell lysates were prepared and western blot analysis was performed against caspase-3, Bcl-2 and Bax, Actin was used as a loading control. ![file] , 
 #1 The paper has undergone a stealth revision or correction, replacing Figs 2 and 4. The version currently provided on the journal website was created modified on 15 January 2021. ![file] The new Figure 2 was prepared in haste and is not entirely convincing. Increasing the contrast and reversing the color allows us to focus on repeated internal details of the cells. ![file] , 
 #3 I am pleased to report that the re-updated Fig 2 in in the current version of this paper (created modified on 20 January 2021) does not resemble either of the two previous Figs 2. Can I take this as an acknowledgement that the previous Fig 2 was fake? ![file] ,