Fig. 8: BMI1 regulates cholesterol homeostasis.
From: BMI1 regulates human erythroid self-renewal through both gene repression and gene activation
A Cholesterol homeostasis depends on cholesterol synthesis, import, export and storage. B CUT&RUN studies reveal BMI1 and RING1B bind the HMGCR locus at higher levels in iSRE than SRE. Data represent merged replicates for all CUT&RUN studies. C The BMI1 inhibitor PTC-209 decreases the expression of BMI1, HMGCR, and HMGCS1 in iSREs at 25 to 35 days of expansion. In contrast, PTC-209 treatment increases expression of p16. 6 independent iSRE cultures expanded for 25 to 35 day and derived from 2 donors, mean. ± SEM. p-value was calculated using a two-tailed Student's t-test. *p < 0.05, **p < 0.01. Source data are provided as a Source Data file. D iSREs contain cytoplasmic droplets that stain with filipin (cholesterol). Representative example of one of two cultures shown. E iSREs contain cytoplasmic droplets that stain with Nile red (lipids). Representative example of one of two cultures shown. F iSREs contain higher levels of cholesterol (filipin stain) compared to primary human proerythroblast (ProE). Staining of both cell populations normalized to primary orthochromatic erythroblasts (OrthoE). Human marrow samples derived from 3 donors. 4 independent iSRE cultures expanded for 25 to 35 day and derived from 2 donors, mean ± SEM. Two-tailed Student's t-test. **p < 0.01. Source data are provided as a Source Data file. G iSREs contain higher levels of lipid rafts (CT-B staining) compared to primary human ProE. Staining of both cell populations normalized to primary OrthoE. Human marrow samples derived from 3 donors. 2 independent iSRE cultures expanded for 25 to 35 day and derived from 2 donors. Paired two-tailed Student's t-test. *p < 0.05 mean ± range. Source data are provided as a Source Data file. H While short-term removal of exogenous lipids does not alter iSRE proliferation, concomitant block of cholesterol synthesis with Ro 48 obviates iSRE proliferation, which can be partially rescued by addition of exogenous lipids. 3 independent iSRE cultures expanded for 25 to 35 day and derived from 2 donors. p-value was calculated based on two-tailed Student's t-test, mean ± SEM. **p < 0.01, ***p < 0.001. Source data are provided as a Source Data file.
