Fig. 1

SYNJ1 is accumulated in neurons, Hirano bodies and plaque-associated dystrophic neurites in AD brains. a Immunostaining of SYNJ1 in hippocampal CA1–2 area of a control case carrying APOEε3/3. In control brains, SYNJ1 immunoreactivity was detected in dendrites in the hippocampal pyramidal neurons (a, arrow). b-d Immunostaining of SYNJ1 in hippocampal CA1–2 area of an AD patient carrying APOEε3/3. Neuronal perikarya and a perinuclear rim were immunostained for SYNJ1 (b). Ovoid intraneuronal inclusions similar to Hirano bodies were stained by anti-SYNJ1 antibody (c, arrowhead). Dystrophic neurites surrounding amyloid plaques were also stained for SYNJ1 (d). e-f In AD brains carrying APOEε4 allele(s), the intensity of SYNJ1 staining is stronger than in AD cases without APOEε4 allele (e). SYNJI positive Hirano bodies were also detected (e, arrowhead). A strong SYNJ1 immunoreactivity was observed in plaque-associated dystrophic neurites in CA1–2 area of AD cases carrying APOEε4 alleles (f). g Quantification of neuronal SYNJ1 immunoreactivity by image analysis in three groups: control without APOEε4 allele, AD group without APOEε4 allele and AD group carrying APOEε4 allele(s) (n = 3 for each group). Paraffin section of control cases bearing APOEε4 allele was not available and was not included in the analyses. SYNJ1 immunoreactivity is significantly increased in AD cases carrying APOEε4 alleles compared to AD cases without APOEε4 allele. *p < 0.05 and **p < 0.01 by one way ANOVA with post-hoc Tukey test. h Quantification of SYNJ1 immunoreactivity by image analysis in plaque-associated dystrophic neurites. SYNJ1 immunoreactivity is significantly increased in AD cases carrying APOEε4 alleles compared to AD cases without APOEε4 allele (n = 3 for each group). **p < 0.01 by unpaired t-test. i. In the hippocampus of DSAD brain, a strong immunostaining for SYNJ1 was detected in neuronal perikarya and in dystrophic neurites surrounding amyloid plaques (asterisk). Scale bars 10 μm