Fig 1: Genes involved in proteoglycan sulfation regulate fibroblast fate stability and cardiac reprogramming.a Schematic depicting rationale for testing proteoglycan sulfation pathway genes. b Expression histogram of GAG elongation and modification genes in MEFs; genes above Log₂(TPM + 1) = 1 (red line) were screened. c Volcano plot of GAG biosynthesis screen results (quadruplicates). d Representative images of siChst7, siHyal1/2, and siControl-transfected iMGT-MEFs on day 3. Myh6-eGFP (green); nuclei (DAPI, blue). Scale bar, 50 μm. e Histogram of Myh6-eGFP⁺ and mCherry⁺ cells following infection with either control lentivirus (pLV-Puro-CMV>empty:P2A:mCherry) or mouse Chst7-overexpressing lentivirus (pLV-Puro-CMV>mChst7 [NM_021715.1]:P2A:mCherry). Cells expressing CHST7–mCherry fail to reprogram, as indicated by the absence of Myh6-eGFP expression. n = 6. f Representative images of lentivirus-infected iMGT-MEFs at day 3. CHST7–mCherry (red), Myh6-eGFP (green), and nuclei (DAPI, blue). Scale bar, 50 μm. g Confocal images of MEFs showing CHST7 (green), Golgin97 (red), and nuclei (DAPI, white). Merged image reveals perinuclear colocalization (yellow) of CHST7 and Golgin97. White arrowheads identify the region of CHST7 and Golgin97 overlap. Scale bar, 1 μm. h Quantification of the percentage of overlapped volume of CHST7:Golgin97 in MEFs measured by Imaris 3D surface reconstruction. Box plots: center line, median (30.9); box limits, upper and lower quartiles (Q3 = 52.9, Q1 = 18.9); whiskers, minimum and maximum values (6.4–94.4). No outliers were detected according to the 1.5× interquartile range (IQR) criterion. n = 118 measurements obtained from 3 individual cells. i Histogram of Myh6-eGFP⁺ cells following treatment with recombinant human Sulfatase-2 (SULF2) at 0.1, 0.2, 0.4, and 0.5 μg/ml, compared to control conditions. A significant increase in cardiac reprogramming is observed at 0.4 and 0.5 μg/ml of SULF2. n = 4. j Representative images of iMGT-MEFs at day three following treatment with 0.5 μg/ml of SULF2 and control conditions. Myh6-eGFP (green) and nuclei (DAPI, blue). Scale bar, 50 μm. Data are mean ± s.d.; two-tailed unpaired Student’s t-test; *P < 0.05, **P < 0.01, ***P < 0.001. n is the number of biological replicates. Source data are provided as a Source data file.