Structural, thermodynamic, and phosphatidylinositol 3‐phosphate binding properties of Phafin2

Tang, Tuo-Xian; Jo, Ami; Deng, Jingren; Ellena, Jeffrey F.; Lazar, Iulia M.; Davis, Richey M.; Capelluto, Daniel G. S.

doi:10.1002/pro.3128

Cited by 12 publications

(12 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both the Phafin2 PH and FYVE domains showed a preference for PtdIns3P. The FYVE domain was highly selective for this phosphoinositide, whereas the PH domain showed a less stringent binding profile and also bound weakly to PtdIns4P and PtdIns5P (Fig 3f) This is in line with previous reports 19, 21 . As we observed that the N-terminal region of Phafin2 was also required for the first Phafin2 localization phase and its deletion had the same effect as impairing the lipid-binding activity of the PH domain, we asked if this region is required to form a functional PH domain.…”

Section: Resultssupporting

confidence: 92%

The PtdIns3P-binding protein Phafin2 escorts macropinosomes through the cortical actin cytoskeleton

Schink

Tan

Spangenberg

et al. 2017

Preprint

View full text Add to dashboard Cite

Uptake of large volumes of extracellular fluid by actin-dependent macropinocytosis plays important roles in infection, immunity and cancer development. A key question is how large macropinosomes are able to squeeze through the dense actin network underlying the plasma membrane in order to move towards the cell centre for maturation. Here we show that, immediately after macropinosomes have been sealed off from the plasma membrane, the PH-and FYVE domain-containing protein Phafin2 is recruited by a mechanism that involves binding to phosphatidylinositol 3-phosphate (PtdIns3P) generated in a non-canonical manner. Phafin2 in turn regulates the actin cross-linking protein Filamin A to promote entry of macropinosomes through the subcortical actin matrix and subsequent maturation. Depletion of Phafin2 inhibits macropinocytic internalization and maturation. We conclude that PtdIns3P and its effector Phafin2 are key components of a system that allows nascent macropinosomes to navigate through the dense subcortical actin network.

show abstract

Section: Resultssupporting

confidence: 92%

The PtdIns3P-binding protein Phafin2 escorts macropinosomes through the cortical actin cytoskeleton

Schink

Tan

Spangenberg

et al. 2017

Preprint

View full text Add to dashboard Cite

show abstract

“…Phafin2 contains a PH and a FYVE domain, both of which are involved in lipid binding ( Fig. 1 A) ( Matsuda-Lennikov et al, 2014 ; Schink et al, 2017 preprint; Tang et al, 2017 , 2020 ). JIP4 interacts with Phafin2 only through the Phafin2 PH domain, as deletion of the PH domain – but not the FYVE domain – abolished expression of the reporter gene in a yeast two-hybrid assay ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In the present study, we show that a previously uncharacterized region of JIP4 interacts with the PH domain of the phosphoinositide-binding protein Phafin2, recruiting JIP4 to early macropinosome membranes. Phafin2 binds PtdIns3P -generated by the PtdIns 3-kinase VPS34 -through its FYVE domain, which localizes it to endosomes and macropinosomes (Pedersen et al, 2012;T.-X. Tang et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

“…In this study, we described that a previously uncharacterized region of JIP4 interacts with the PH domain of the phosphoinositide-binding protein Phafin2, recruiting JIP4 to the membrane of early macropinosomes. Phafin2 binds PtdIns3P – generated by the PtdIns 3-kinase VPS34 – through its FYVE domain, which localizes it to endosomes and macropinosomes ( Pedersen et al, 2012 ; Tang et al, 2017 ). Our data show that genetic ablation of Phafin2 or the removal of PtdIns3P disrupt the localization of JIP4 to macropinosomes.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

JIP4 is recruited by the phosphoinositide-binding protein Phafin2 to promote recycling tubules on macropinosomes

Tan

Nähse

Campsteijn

et al. 2021

Journal of Cell Science

View full text Add to dashboard Cite

Macropinocytosis allows cells to take up extracellular material in a non-selective manner into large vesicles called macropinosomes. After internalization, macropinosomes acquire phosphatidylinositol 3-phosphate (PtdIns3P) on their limiting membrane as they mature into endosomal-like vesicles. The molecular mechanisms that mediate recycling of membranes and transmembrane proteins from these macropinosomes still need to be defined. Here we report that JIP4, a protein previously described to bind to microtubule motors, is recruited to tubulating subdomains on macropinosomes by the PtdIns3P-binding protein Phafin2. These JIP4-positive tubulating subdomains on macropinosomes contain F-actin, the retromer recycling complex, and a retromer cargo, VAMP3. Disruption of the JIP4-Phafin2 interaction, deletion of Phafin2, or inhibition of PtdIns3P production by VPS34 impairs JIP4 recruitment to macropinosomes. While knockout of JIP4 suppresses tubulation, overexpression enhances tubulation from macropinosomes. JIP4 knockout cells display increased retention of macropinocytic cargo in both early and late macropinosomes. Collectively, these data identify JIP4 and Phafin2 as components of a tubular recycling pathway that operates from macropinosomes.

show abstract

“…Although membrane nucleation has been established as a key step in the autophagic process, the origin of the membrane that gives rise to the phagophore, and subsequently the autophagosome, remains unclear. Elongation and expansion of the phagophore membrane are key steps in the autophagic process (17). The autophagy related protein Atg12-Atg5-Atg16 and Atg8 conjugation systems, which are inter-related ubiquitin-like conjugation pathways, regulate this stage in both yeast and mammals (18).…”

Section: The Molecular Mechanism Of Autophagymentioning

confidence: 99%

Role of autophagy in advanced atherosclerosis

Zhu

Fan

Zhang

et al. 2017

Molecular Medicine Reports

View full text Add to dashboard Cite

Abstract. Atherosclerosis (AS) remains the leading cause for global cardiovascular disease morbidity and mortality, and a major cause of cardiopathy, myocardial infarction and peripheral vascular diseases. Macrophages serve a critical role in atherosclerotic plaque stabilization and rupture, and the selective removal of macrophages may be beneficial in improving plaque stability. Autophagy is a process of self-feeding, during which cytoplasmic proteins or organelles are packaged into vesicles and fused with the lysosome to form an autophagosome. The newly formed autophagosome can degrade internalized proteins, and this process may be used to serve the metabolic and self-renewal requirements of the cell. Autophagy serves an important role in maintaining cell homeostasis and promoting cell survival, and therefore an imbalance in autophagy is closely associated with multiple diseases. Contents1. Introduction 2. The molecular mechanism of autophagy 3. Autophagy in the vascular system 4. Autophagy in AS 5. Conclusions IntroductionAutophagy is a process of cellular repair and survival, during which cytoplasmic components are sequestered into double-membrane vesicles. Previous research has revealed that autophagy is stimulated in advanced atherosclerotic plaques by oxidized lipids, inflammation and metabolic stress (1). Autophagy is beneficial in promoting cellular recovery in adverse environments; it is also valuable in inhibiting apoptosis. In advanced atherosclerosis (AS), macrophage apoptosis, together with defective phagocytic clearance of the apoptotic cells, promotes plaque necrosis, which results in acute atherothrombotic cardiovascular events (2). Basal autophagy is beneficial in early AS, however a detrimental effect is observed in advanced AS plaques (3); autophagy is capable of protecting cells from oxidative stress via the degradation of damaged intracellular material; however, excessively stimulated autophagic activity may result in significant destruction of the cytosol (1). The latter scenario leads to programmed cell death and may cause vascular endothelial cell (VEC) death, which results in plaque destabilization. Endothelial injury or death represents a predominant mechanism of acute clinical events, due to the promotion of lesional thromboses (4). Furthermore, insufficient autophagic activity also reduces free cholesterol and apolipoprotein A-I (5), and this decreases the amount of high-density lipoprotein. Insufficient and excessive autophagy of VECs are therefore both injurious, and the regulation of autophagic homeostasis may be important in the treatment of AS. The molecular mechanism of autophagyWhen Ashford and Porter (6) perfused rat livers with glucagon, they discovered a large increase in the number of cellular lysosomes. This phenomenon of self-feeding was referred to as autophagy. This process involves the packaging of cytoplasmic proteins or organelles into vesicles, followed by lysosomal fusion, to form an autophagic lysosome; a cellular event which aids in metabolism and in the renewal...

show abstract

Structural, thermodynamic, and phosphatidylinositol 3‐phosphate binding properties of Phafin2

Cited by 12 publications

References 33 publications

The PtdIns3P-binding protein Phafin2 escorts macropinosomes through the cortical actin cytoskeleton

The PtdIns3P-binding protein Phafin2 escorts macropinosomes through the cortical actin cytoskeleton

JIP4 is recruited by the phosphoinositide-binding protein Phafin2 to promote recycling tubules on macropinosomes

Role of autophagy in advanced atherosclerosis

Contact Info

Product

Resources

About