Release of FGF1 and p40 synaptotagmin 1 correlates with their membrane destabilizing ability

Graziani, Irene; Bagalá, Cinzia; Duarte, Maria F.; Soldi, Raffaella; Kolev, Vihren N.; Tarantini, Francesca; Kumar, Thallapuranam Krishnaswamy Suresh; Doyle, Andrew W.; Neivandt, David J.; Maciag, Thomas; Prudovsky, Igor

doi:10.1016/j.bbrc.2006.08.021

Cited by 29 publications

(42 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, FGF-1, a close relative of FGF-2, has been proposed to be able to acquire a so-called molten globule conformation that might allow the protein to penetrate membranes (Prudovsky et al, 2003). Interestingly, FGF-1 has been suggested to destabilize membranes through its ability to interact with acidic membrane lipids (Graziani et al, 2006). Biochemical studies using chemically defined liposomes to reconstitute FGF-2 membrane translocation in vitro as well as genome-wide RNAi screening procedures to identify gene products (e.g.…”

Section: Fgf-2 Targeting and Membrane Translocation -A Speculative Hymentioning

confidence: 99%

Unconventional secretion: an extracellular trap for export of fibroblast growth factor 2

Nickel

2007

Journal of Cell Science

View full text Add to dashboard Cite

Andrei et al., 2004) and by plasma membrane shedding (MacKenzie et al., 2001). Here, I discuss a new model for the molecular mechanism of FGF-2 secretion based on recent data. Key aspects of this model are: (1) direct translocation of FGF-2 from the cytoplasm across the plasma membrane in the absence of transport vesicles; (2) the independence of membrane translocation from ATP hydrolysis or a membrane potential; (3) diffusion-controlled membrane translocation process; and (4) an extracellular molecular trap formed by membrane-proximal heparan sulfates that ensures directional transport of FGF-2 into the extracellular space. Passive versus active mechanisms of translocationCentral to the molecular mechanism of FGF-2 secretion is the question of what actually drives translocation of FGF-2 across the plasma membrane in terms of energy requirements. Studies employing an intact cell model system led to the proposal that the overall process of FGF-2 secretion in living cells depends on ATP hydrolysis (Florkiewicz et al., 1995). However, the early data did not really demonstrate that membrane translocation itself is driven by ATP hydrolysis. Depletion of ATP from intact cells affects many fundamental cellular functions and, therefore, the inefficient FGF-2 secretion observed could well be an indirect effect. An in vitro approach using plasma-membrane-derived inside-out vesicles shows that FGF-2 can translocate directly across the plasma membrane but that neither ATP hydrolysis nor a membrane potential is required (Schäfer et al., 2004). FGF-2 thus appears to traverse the plasma membrane by passive diffusion.At first glance, passive diffusion seems unusual compared with other membrane translocation processes, such as import into the mitochondrial matrix (driven by ATP hydrolysis) (Neupert and Herrmann, 2007) or the bacterical twin arginine secretion system (driven by a membrane potential) (Lee et al., Several secretory proteins are released from cells by mechanisms that are distinct from the classical endoplasmic reticulum (ER)/Golgi-mediated secretory pathway. Recent studies unexpectedly revealed that the interaction between one such protein, fibroblast growth factor 2 (FGF-2), and cell surface heparan sulfate proteoglycans (HSPGs) is essential for secretion. FGF-2 mutants that cannot bind to heparan sulfates are not secreted, and cells that do not express functional HSPGs cannot secrete wild-type FGF-2. FGF-2 appears to be secreted by direct translocation across the plasma membrane in an ATP-and membrane-potentialindependent manner. I propose that its translocation across the membrane is a diffusion-controlled process in which cell surface HSPGs function as an extracellular molecular trap that drives directional transport of FGF-2.

show abstract

Section: Fgf-2 Targeting and Membrane Translocation -A Speculative Hymentioning

confidence: 99%

Unconventional secretion: an extracellular trap for export of fibroblast growth factor 2

Nickel

2007

Journal of Cell Science

View full text Add to dashboard Cite

show abstract

“…[17][18][19][20][21] Such studies often quantitate CF release but do not compare the results with the transport of other species. In several studies of the SAT family of transporters developed in our lab, we have used carboxyfluorescein release to assay anion transport through vesicular bilayers.…”

Section: Introductionmentioning

confidence: 99%

Transport of chloride and carboxyfluorescein through phospholipid vesicle membranes by heptapeptide amphiphiles

Ferdani¹,

Li²,

Pajewski³

et al. 2007

Org. Biomol. Chem.

View full text Add to dashboard Cite

Seven synthetic anion transporters (SAT) of the general form R 2 N-COCH 2 OCH 2 CO-(Gly) 3 -Pro-(Gly) 3 -OR' were prepared. Three pairs of compounds each contained twin n-hexyl, n-decyl, and noctadecyl (R) groups at the N-terminus and one contained twin n-tetradecyl groups. Three of the compounds were C-terminated by benzyl and three by heptyl (R') residues. The ability of these compounds to mediate ion release from phospholipid vesicles was assessed. Chloride release was measured by ion selective electrode measurements and by chloride quenching of the fluorescent dye lucigenin. Transport of the anion carboxyfluorescein (CF) was measured by fluorescence dequenching. Differences in both the C-(R') and N-terminal (R) residues within the ionophores affected anion transport. The chloride release data acquired by ion selective electrode and fluorescence methods were similar but not identical. A possible carrier mechanism for Cl -transport was discredited. Both Cl -and CF anions were released from vesicles by these compounds. The results of CF and Cl -transport showed good consistency when the ionophore's N-terminal chains were either decyl or octadecyl but not when they were hexyl. The transport of CF and Cl -appears to be fundamentally different when R is C 6 compared to C 10 or C 18 . Differences between the behavior of SATs with Cl -and CF were also reflected in negative ion mass spectrometric studies.

show abstract

“…In addition, Sanz and Gallego showed that aFGF exhibits high lipid binding affinity at acidic pH (32). We have recently demonstrated that the mutations of specific lysine clusters in aFGF and p40 Syt1 result in a significant decrease of their ability to destabilize liposomes composed of acidic phospholipids and a dramatic inhibition of their non-classical release from the cells (33). Bychkova et al, investigating the structure of cytochrome c under acid conditions, suggested that the negative membrane potential creates an acidic microenvironment that in-turn causes a denaturation effect on proteins, leading to their partial unfolding (34).…”

mentioning

confidence: 97%

Relevance of Partially Structured States in the Non-Classical Secretion of Acidic Fibroblast Growth Factor

et al. 2007

Self Cite

View full text Add to dashboard Cite

Acidic fibroblast growth factor (aFGF) is a signal peptide-less protein that is secreted into the extracellular compartment as part of a multiprotein release complex, consisting of aFGF, S100A13 (a calcium binding protein), and a 40 kDa (p40) form of synaptotagmin (Syt1), a protein that participates in the docking of a variety of secretory vesicles. p40 Syt1, and specifically its C2A domain, is believed to play a major role in the non-classical secretion of the aFGF release complex mediated by the interaction of aFGF and p40 Syt1with the phospholipids of the cell membrane inner leaflet. In the present study, we investigate the structural characteristics of aFGF and the C2A domain of p40 Syt1 under acidic conditions, using a variety of biophysical techniques including multidimensional NMR spectroscopy. Urea-induced equilibrium unfolding (at pH 3.4) of both aFGF and the C2A domain are non-cooperative and proceed with the accumulation of stable intermediate states. 1-Anilino-8-napthalene sulfonate (ANS) binding and size-exclusion chromatography results suggest that both aFGF and the C2A domain exist as partially structured states under acidic conditions (pH 3.4). Limited trypsin digestion analysis and 1 H-15 N chemical shift perturbation data reveal that the flexibility of certain portions of the protein backbone is increased in the partially structured state(s) of aFGF. The residues that are perturbed in the partially structured state(s) in aFGF are mostly located at the N-and C-terminal ends of the protein. In marked contrast, most of the interactions stabilizing the native secondary structure are preserved in the partially structured state of the C2A domain. Isothermal titration calorimetry data indicate that the binding affinity between aFGF and the C2A domain is significantly enhanced at pH 3.4. In addition, both aFGF and the C2A domain exhibit much higher lipid binding affinity in

show abstract

Release of FGF1 and p40 synaptotagmin 1 correlates with their membrane destabilizing ability

Cited by 29 publications

References 45 publications

Unconventional secretion: an extracellular trap for export of fibroblast growth factor 2

Unconventional secretion: an extracellular trap for export of fibroblast growth factor 2

Transport of chloride and carboxyfluorescein through phospholipid vesicle membranes by heptapeptide amphiphiles

Relevance of Partially Structured States in the Non-Classical Secretion of Acidic Fibroblast Growth Factor

Contact Info

Product

Resources

About