Journal: ACS nano

Article Title: Profiling the Serum Protein Corona of Fibrillar Human Islet Amyloid Polypeptide

doi: 10.1021/acsnano.8b02346

Figure Lengend Snippet: Formation and characterization of IAPP amyloid-protein corona in FBS. A: TEM imaging (upper panel; scale: 100 nm) and associated analysis of fibril diameter (lower panel; n = 100 points sampled) of amyloid exposed to FBS over 24 h, with a comparative measurement after 24 h exposure to human plasma proteins. **** p < 0.0001. B: QCM characterization of amyloid corona formation on an IAPP amyloid functionalized surface (IAPP pre-coat) or gold (uncoated) under flow over 1 h (left panel) with comparison of the soft (pre-wash) and hard (post-wash) coronae (right panel). Error: SEM (n = 4). C: HIM imaging of βTC6 cells exposed for 30 min in vitro to either amyloid (I), amyloid + FBS, pre-incubated for 2 h at RT (II), FBS alone (III), or no treatment applied (IV). Scale: 4 μm. Concentration of IAPP amyloid in all experiments: 0.1 mg/mL; FBS: 0.5 mg/mL.

Article Snippet: Lyophilized human islet amyloid polypeptide (IAPP) monomers (37-residue: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY, disulfide bridge: 2–7; MW: 3,906; sourced from either AnaSpec or Abcam) were allowed to fibrillate in Milli-Q water (pH 6.5) for > 1 week at room temperature to allow complete conversion of monomers and lower order amyloid pathway species to mature amyloid fibrils.

Techniques: Imaging, Clinical Proteomics, Comparison, In Vitro, Incubation, Concentration Assay

Journal: Biomacromolecules

Article Title: Star Polymers Reduce Islet Amyloid Polypeptide Toxicity via Accelerated Amyloid Aggregation

doi: 10.1021/acs.biomac.7b01301

Figure Lengend Snippet: (A) ThT fluorescence of IAPP in the presence of PHEA stars over 24 h. Dotted lines represent sigmoidal curve fitting (least-squares fit); error is SEM ( n = 2). (B) Secondary structure transitions in IAPP mapped by circular dichroism at 0, 2.5, and 24 h time points. Lines are intended to guide the eye. The concentration of IAPP in all experiments is 25 μM.

Article Snippet: Human islet amyloid polypeptide monomers (IAPP; disulfide bridge: 2–7; MW: 3,906; 37 residue: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY; >95% pure by HPLC) were obtained in lyophilized powder form from AnaSpec and were made up to a 200 μM stock immediately prior to an experiment or allowed to fibrillate at 25 °C for >5 days to produce mature IAPP amyloids.

Techniques: Fluorescence, Circular Dichroism, Concentration Assay

Journal: Biomacromolecules

Article Title: Star Polymers Reduce Islet Amyloid Polypeptide Toxicity via Accelerated Amyloid Aggregation

doi: 10.1021/acs.biomac.7b01301

Figure Lengend Snippet: (A) TEM imaging of fibrillating IAPP (IAPP) and mature IAPP amyloids (Amyloid) in the presence and absence of PHEA stars after 24 h incubation. Stelliform amyloids are seen at PHEA:IAPP 1:5. Scale = 100 nm. (B) Structural analysis of amyloid fibrils visualized in (A). IAPP concentration in all experiments is 25 μM.

Article Snippet: Human islet amyloid polypeptide monomers (IAPP; disulfide bridge: 2–7; MW: 3,906; 37 residue: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY; >95% pure by HPLC) were obtained in lyophilized powder form from AnaSpec and were made up to a 200 μM stock immediately prior to an experiment or allowed to fibrillate at 25 °C for >5 days to produce mature IAPP amyloids.

Techniques: Imaging, Incubation, Concentration Assay

Journal: Biomacromolecules

Article Title: Star Polymers Reduce Islet Amyloid Polypeptide Toxicity via Accelerated Amyloid Aggregation

doi: 10.1021/acs.biomac.7b01301

Figure Lengend Snippet: Protective effect of PHEA stars against IAPP-mediated cytotoxicity in pancreatic beta cells and islets. (A) In vitro cytotoxicity of fibrillating IAPP and mature IAPP amyloids in the presence and absence of PHEA in βTC6 cells over 24 h. Error = SEM ( n = 3). (B) Ex vivo cytotoxicity of fibrillating IAPP and IAPP:PHEA at a 1:5 molar ratio in mouse islets after 48 h incubation. Flow cytometry data is representative of n = 5 experiments summarized in the graph. Error = SEM. **** p < 0.0001, one-way ANOVA with Tukey’s correction.

Article Snippet: Human islet amyloid polypeptide monomers (IAPP; disulfide bridge: 2–7; MW: 3,906; 37 residue: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY; >95% pure by HPLC) were obtained in lyophilized powder form from AnaSpec and were made up to a 200 μM stock immediately prior to an experiment or allowed to fibrillate at 25 °C for >5 days to produce mature IAPP amyloids.

Techniques: In Vitro, Ex Vivo, Incubation, Flow Cytometry

Journal: Biomacromolecules

Article Title: Star Polymers Reduce Islet Amyloid Polypeptide Toxicity via Accelerated Amyloid Aggregation

doi: 10.1021/acs.biomac.7b01301

Figure Lengend Snippet: Aggregation free energy landscapes of IAPP without (A) and with (B) PHEA. Three-dimensional potentials of mean force (PMFs) with respect to IAPP oligomer size and degree of fibrillization were used to derive the free energy landscapes in front and top views. Snapshot structures with IAPP in cartoon and PHEA polymers in stick are shown to illustrate the basins and saddles of the energy landscapes.

Article Snippet: Human islet amyloid polypeptide monomers (IAPP; disulfide bridge: 2–7; MW: 3,906; 37 residue: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY; >95% pure by HPLC) were obtained in lyophilized powder form from AnaSpec and were made up to a 200 μM stock immediately prior to an experiment or allowed to fibrillate at 25 °C for >5 days to produce mature IAPP amyloids.

Techniques: