To explore the mechanismof forkhead box p1 (FoxP1) , a forkhead box transcription factor, mediates the autophagy pathway to regulate the process of transforming growth factor-β1 (TGF-β1) -induced endothelial to mesenchymal transition (EndMT) .

The human umbilical vein endothelial cells were divided into the following groups: control group (Blank) , TGF-β1-induced EndMT model group (TGF-β1) , small interfering RNA negative control group (TGF-β1+si-NC) , FoxP1 small interfering RNA group (TGF-β1+si-FoxP1) , overexpressing RNA negative control group (TGF-β1+oe-NC) , FoxP1 overexpressing group (TGF-β1+oe-FoxP1) , and FoxP1 overexpression combined with an autophagy inhibitor group (TGF-β1+oe-FoxP1+3-MA) . Western blot were used to detect the expression of endothelial、mesenchymal markers and collagen. The mCherry-EGFP-LC3 dual fluorescence system was used to detect autophagy status. Cell migration ability was assessed through scratch assay. The independent samples t-test was used for the comparisons between two groups, while for comparisons among multiple groups, one-way analysis of variance (ANOVA) was employed, and the LSD-t method was used for pairwise comparisons.

Western blot results showed that, compared to the control group, the expression of endothelial markers VE-cadherin and CD31 were decreased in the TGF-β1 group, while the expression of mesenchymal markers α-SMA,Vimentin and collagen proteins Collagen Ⅰ (3.08 ± 0.09 vs 1.00 ± 0.08) , Collagen Ⅲ (3.14 ± 0.10 vs 1.00 ± 0.05) were increased. In addition, the cell migration ability [ (75.20 ± 4.30) %vs (36.80 ± 2.60) %] and the expression of p62 (2.24 ± 0.07 vs 1.00 ± 0.07) were increased in TGF-β1 group when compared to control group, while the expression levels of Beclin-1 (0.49 ± 0.03比1.00 ± 0.02) and LC3 Ⅱ/Ⅰ (0.17 ± 0.01 vs 1.00 ± 0.08) were decreased (all P < 0.01) . Compared to the TGF-β1+oe-NC group, the expression of VE-cadherin, CD31 and Beclin-1 (0.82 ± 0.01 vs 0.49 ± 0.03) , LC3 Ⅱ/Ⅰ (0.55 ± 0.02 vs 0.20 ± 0.01) (all P < 0.01) were increased in the TGF-β1+oe-FoxP1 group, while the expression of α-SMA, Vimentin and collagen proteins Collagen Ⅰ (2.08 ± 0.10 vs 4.38 ± 0.15) , Collagen Ⅲ (1.86 ± 0.07 vs 3.60 ± 0.14) as well as p62 (1.77 ± 0.09 vs 2.24 ± 0.08) , were decreased, along with areduced cell migration ability [ (46.66 ± 5.15) %比(77.56 ± 7.30) %] (all P < 0.01) . Compared to the TGF-β1+oe-FoxP1 group, the expression of Beclin-1 (1.60 ± 0.03 vs 1.96 ± 0.02) , LC3 Ⅱ/Ⅰ (2.20 ± 0.04 vs 3.88 ± 0.16) and E-cadherin, CD31 were decreased in the TGF-β1+oe-FoxP1+3-MA group, while the expression of p62 (0.70 ± 0.02 vs 0.49 ± 0.05) , Collagen I (0.80 ± 0.02 vs 0.51 ± 0.03) , CollagenⅢ (0.70 ± 0.01 vs 0.29 ± 0.02) and α-SMA, Vimentin were increased, along with the enhanced cell migration ability [ (58.63 ± 6.19) %比(40.84 ± 5.27) %] (all P < 0.01) .

Overexpression of FoxP1 can activate the autophagy pathway to inhibit the TGF-β1-induced EndMT process,while could provide a novel cytological perspective for the mechanistic research and therapeutic approaches to myocardial fibrosis.