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. 2021 Aug 13;125(8):1146–1157. doi: 10.1038/s41416-021-01510-x

Fig. 1. Loss of PRDX1 in MFs promotes collagen remodelling in mammary glands of a syngeneic mouse model vivo and MFs in vitro.

Fig. 1

a shPRDX1-4 or EV MFs were transplanted into fat pads of 8-week-old female BALB/c mice together with GFP+ 67NR breast cancer cells. One week after transplantation, glands were harvested and analysed by multiphoton microscopy. b Quantification of collagen intensities. Bars indicate EV (black) or sh (white) for 1 or 2 weeks. c–g Second-harmonic generation (SHG) imaging is used to identify collagen fibres which were then analysed using curvelet transformation (CT) and fibre extraction (FIRE) algorithms available through open-source software (see “Materials and methods”). Eight images of eight tumours in four mice for each MF genotype (EV or shPRDX1 MFs, respectively) were analysed. c SHG images overlayed with CT-FIRE tracing (right) for collagen length. Statistical test: Student t test. d Dot plot showing the frequency of average collagen length per image; for EV an average of 903 fibres/image were analysed and for shPRDX1 a total of 996 fibres/image were analysed; Statistical test: Student’s t test. e Dot plot showing significant differences in alignment coefficients in mammary. Statistical test: Student’s t test. f SHG images (overlayed with CT-FIRE tracing for collagen fibre perpendicular angle distribution 0–90°). g Histogram showing significant differences in the frequency of angles. *P < 0.05; **P < 0.005. Statistical test: Student’s t test; h Post mammary gland injection, at weeks 1, 2 and 4, tumour size was measured by calliper. i Scrambled control shRNA (scr) or shRNA PRDX1 clones (sh2 or sh4) MFs were plated in a 48-well plate and incubated with 5% CO2 and 5% O2 at 37 °C for 6 days. Pepsin-digested samples were separated by SDS-PAGE under non-reducing conditions and silver-stained to compare collagen forms. j, k PRDX1-deficient MFs have increased lower molecular weight α-collagen (black), cross-linked higher molecular weight β-collagen (grey) and β/α-collagen ratio. *P < 0.05; **P < 0.005.