Journal: bioRxiv

Article Title: Peptides alleviate cognitive impairment by inhibiting and disassembling amyloid-β aggregates in Alzheimer’s disease

doi: 10.1101/2025.05.28.656730

Figure Lengend Snippet: IQIG and VQVG inhibited Aβ aggregation in vitro. a . Domain structures of RIPK1 and RIPK3 and the alignment of RHIMs. Length is indicated in the number of amino acids. KD, kinase domain; ID, intermediate domain; RHIM, RIP homotypic interaction motif; DD, death domain. The RHIM consensus IQIG and VQV(I)G from human and mouse RIPKs are shown in red. b . Unrestrained protein structure alignment of Aβ amyloid (PDB 2LMO and PDB 2LMP, green), RIPK1 (PDB 5V7Z, yellow), and RIPK3 (PDB 5V7Z, blue). c . Domain structure of the amyloid precursor protein (APP) and amino acid sequence alignment of Aβ42, IQIG, and VQVG. Identical sequences are shaded in red. Length is indicated in the number of amino acids. TM, transmembrane. AICD, the APP intracellular domain. Aβ42 domain is highlighted in red. d . Schematic representation for the potential working mechanism of IQIG or VQVG (purple) on its inhibition of Aβ polymerization (green). e-f . The polymerization of Aβ40 ( e ) or Aβ42 ( f ) was monitored by the thioflavin T (ThT) fluorescence. Aβ (10 μM) was incubated with 20 μM ThT and the corresponding ratio of IQIG or VQVG peptides at 25 °C. g-h . Analysis of Aβ40 or Aβ42 aggregates by negative staining electron microscopy. Aβ40 (20 μM) and Aβ42 (20 μM) were incubated with or without the tetrapeptide IQIG (2 μM) or VQVG (2 μM) for 24 h. Scale bars, 100 nm. i-j . The polymerization of Aβ40 ( i ) or Aβ42 ( j ) was monitored by the ThT fluorescence. Aβ (10 μM) was incubated with 20 μM ThT and the corresponding ratio of IQIG, VQVG, GIQI, GVQV, AYNY, DNNY, and GGGG peptides at 25 °C. All data are representative of three independent experiments.

Article Snippet: The primary antibodies for immunostaining were as follows: rabbit anti-Aβ (1:100, ab20106, Abcam), rabbit anti-GFAP (1:100, ab68428, Abcam), rabbit anti-Iba1 (1:100, ab178846, Abcam), rabbit anti-p-tau (1:100, ab92676, Abcam), mouse anti-RIPK1 (1:100, sc-133102, Santa Cruz Biotechnology) and mouse anti-RIPK3 (1:100, sc-374639, Santa Cruz Biotechnology).

Techniques: In Vitro, Sequencing, Inhibition, Fluorescence, Incubation, Negative Staining, Electron Microscopy

Journal: bioRxiv

Article Title: Peptides alleviate cognitive impairment by inhibiting and disassembling amyloid-β aggregates in Alzheimer’s disease

doi: 10.1101/2025.05.28.656730

Figure Lengend Snippet: IQIG and VQVG reduced Aβ plaques, p-tau tangles, and microglial plaques in the brains of the APP/PS1 mice. The APP/PS1 or wild type mice subjected to behavioral tests were used for brain analyses. a . The hippocampal and cortex regions were stained with the amyloid-specific binding dye ThS or the anti-Aβ antibody (scale bars, 500 μm). b . IQIG and VQVG decreased ThS-positive plaques the APP/PS1 mice. c-e . Amyloid plaque numbers were quantified in the total brain ( c ), hippocampus ( d) , and cortex regions ( e ). f-i . Immunostaining for p-tau ( f ), Iba1 ( g ), and DAPI after administration of vehicle, IQIG, or VQVG in the hippocampus of the APP/PS1 mice, or wild type mice ( n = 6 for each group). Scale bars, 200 μm. Quantification results of p-tau and Iba1 are shown in h and i . j-k . Western blotting analyses of Aβ oligomer, RIPK1, and RIPK3 in the insoluble hippocampal ( left ) and soluble hippocampal ( right ) lysates. The quantification results of Aβ oligomer expression levels are shown in k . Data are denoted as mean ± SD, One-way analysis of variance was performed (* p < 0.05, ** p < 0.01, *** p < 0.001 and **** p < 0.0001). All data are representative of three independent experiments.

Article Snippet: The primary antibodies for immunostaining were as follows: rabbit anti-Aβ (1:100, ab20106, Abcam), rabbit anti-GFAP (1:100, ab68428, Abcam), rabbit anti-Iba1 (1:100, ab178846, Abcam), rabbit anti-p-tau (1:100, ab92676, Abcam), mouse anti-RIPK1 (1:100, sc-133102, Santa Cruz Biotechnology) and mouse anti-RIPK3 (1:100, sc-374639, Santa Cruz Biotechnology).

Techniques: Staining, Binding Assay, Immunostaining, Western Blot, Expressing