Journal: HemaSphere

Article Title: A cellular reporter system to evaluate endogenous fetal hemoglobin induction and screen for therapeutic compounds

doi: 10.1002/hem3.139

Figure Lengend Snippet: Design of gRNAs specifically targeting the HBG1 3′‐UTR in HUDEP2 cells. (A) The human HBB locus on chromosome 11 contains 5 β‐like globin genes, arranged in developmental order of expression, and an upstream locus control region (LCR; red arrows indicate DNaseI hypersensitive sites). (B) Comparison of the HBG1/2 3′‐UTR sequences from the GRCh38 reference genome identified two HBG1 ‐specific nucleotides at positions +17 and +55 downstream of the TGA stop codon. (C) In HUDEP2 DNA, additional gene‐specific nucleotides were identified. The +55 adenosine is allele‐specific rather than gene‐specific. (D) Two gRNAs designed to specifically target the HBG1 3′‐UTR.

Article Snippet: Primary antibodies recognized γ‐globin (sc‐21756; Santa Cruz Biotechnology), β‐globin (sc‐21757), and NPM1 (ab10530; Abcam).

Techniques: Expressing, Control, Comparison

Journal: HemaSphere

Article Title: A cellular reporter system to evaluate endogenous fetal hemoglobin induction and screen for therapeutic compounds

doi: 10.1002/hem3.139

Figure Lengend Snippet: C‐terminal tagging of the HBG1 gene. (A) Schematic approach of tagging HBG1 with a GFP reporter gene in the fetal‐like HUDEP1 cells. (B, C) Since HUDEP1 cells express HbF, cells expressing Aγ‐GFP can be enriched by FACS for sequence analysis confirming the successful tagging of HBG1 . Tagging of HBG1 is possible albeit at low (<1%) efficiency. (D, E) GFP‐sorted cells under phase contrast and fluorescence microscope. Scale bar = 50 µm. (F) Fluorescence read‐out on a range of pomalidomide concentrations in culture medium showed compound auto‐fluorescence. (G) Luminescence read‐out was not affected by the auto‐fluorescence of pomalidomide. (H) Schematic representation of the tagging strategy with the HiBiT tag, which was optimized in HUDEP2 cells displaying high HbF expression. (I) Use of a single‐strand DNA template and improved delivery method (RNP instead of plasmid‐based) increased the knockin efficiency. Twenty‐three percent (8/35) of single‐cell clones expanded after nucleofection showed an increased luminescent signal. (J) The γ‐globin monoclonal antibody detected an additional slower‐migrating band in the homozygously tagged Clone #10. (K) Only the slower‐migrating band was detected when the western blot was probed for a HiBiT luminescent signal.

Article Snippet: Primary antibodies recognized γ‐globin (sc‐21756; Santa Cruz Biotechnology), β‐globin (sc‐21757), and NPM1 (ab10530; Abcam).

Techniques: Expressing, Sequencing, Fluorescence, Microscopy, Plasmid Preparation, Knock-In, Clone Assay, Western Blot

Journal: HemaSphere

Article Title: A cellular reporter system to evaluate endogenous fetal hemoglobin induction and screen for therapeutic compounds

doi: 10.1002/hem3.139

Figure Lengend Snippet: Use of Aγ‐HiBiT reporter cells to evaluate genetic fetal hemoglobin (HbF)‐induction. (A) Deconvolution of Sanger sequence traces showed Cas9‐mediated disruption of a BCL11A binding site (TGACCA) in the HBG1/2 promoter of Aγ‐HiBiT reporter cells. Similar results were obtained in control HUDEP2 cells. The red arrow indicates the predicted Cas9 cleavage position relative to the transcription start site. (B) On western blot, the γ‐globin antibody detected HBG1/2 induction after promoter disruption of Aγ‐HiBiT reporter and control HUDEP2 cells. NPM1 served as loading control. (C–E) High‐performance liquid chromatography detected an increase in HbF tetramers after genetic editing of the Aγ‐HiBiT reporter cells similar to the increase observed in edited control HUDEP2 cells. (F) Deconvolution of Sanger sequence traces showed Cas9‐mediated disruption of an enhancer of HbF‐repressor BCL11A in Aγ‐HiBiT reporter cells. The red arrow indicates the predicted cleavage position. (G) On western blot, the γ‐globin antibody detected HBG1/2 induction after BCL11A enhancer disruption of the Aγ‐HiBiT reporter cells. (H) The HiBiT Lytic assay reported Aγ‐HiBiT induction after the Aγ‐HiBiT reporter cells had been exposed to the two orthogonal genetic approaches. Note the logarithmic scale (10 log).

Article Snippet: Primary antibodies recognized γ‐globin (sc‐21756; Santa Cruz Biotechnology), β‐globin (sc‐21757), and NPM1 (ab10530; Abcam).

Techniques: Sequencing, Disruption, Binding Assay, Control, Western Blot, High Performance Liquid Chromatography

Journal: HemaSphere

Article Title: A cellular reporter system to evaluate endogenous fetal hemoglobin induction and screen for therapeutic compounds

doi: 10.1002/hem3.139

Figure Lengend Snippet: Use of pomalidomide as a positive control for fetal hemoglobin (HbF) induction. (A) Primary erythroid progenitors derived from a healthy donor were treated with 10 μM pomalidomide under proliferation conditions for 5 days and then switched to differentiation conditions. Samples for quantitative reverse‐transcription polymerase chain reaction analysis of γ‐globin expression were taken at Days 0, 3, 5 (proliferation conditions) and Days 8 and 10 (differentiation conditions, red font). Treatment: gray: control; blue: dimethyl sulfoxide (DMSO) (solvent control), purple: 10 μM pomalidomide. N = 3 independent cultures; error bars indicate standard deviations. (B) Western blot analysis of β‐globin and γ‐globin expression of DMSO and pomalidomide (Pom) treated samples shown in (A) HbF levels were measured by high‐performance liquid chromatography (HPLC) at Day 10 of culture. (C) Primary erythroid progenitors derived from an sickle cell disease patient were treated with 10 μM pomalidomide under proliferation conditions for 5 days and then switched to differentiation conditions. Other details are as for panel A. (D) Western blot analysis of β‐globin and γ‐globin expression of DMSO and pomalidomide (Pom) treated samples shown in (C). HbF levels could not be measured by HPLC at Day 10 of culture due to insufficient number of cells. (E) HUDEP2 and Aγ‐HiBiT reporter cells were treated with 10 μM pomalidomide under proliferation conditions for 5 days and then switched to differentiation conditions. H = HUDEP2 cells; R = Aγ‐HiBiT reporter cells. Other details are as for panel A. (F) HbF levels were measured by HPLC at Day 10 of culture of HUDEP2 cells and Aγ‐HiBiT reporter cells. See panel (E) for other details. (G) The HiBiT lytic assay reported Aγ‐HiBiT induction after the Aγ‐HiBiT reporter cells had been exposed to 10 μM pomalidomide (see E, F). (H) Western blot analysis of β‐globin and γ‐globin expression of control, DMSO, and pomalidomide (Pom)‐treated HUDEP2 cells (see E, F). (I) Western blot analysis of β‐globin and Aγ‐HiBiT expression of control, DMSO, and pomalidomide (Pom)‐treated Aγ‐HiBiT reporter cells (see E, F). (J, K) Viability and HiBiT lytic assays of Aγ‐HiBiT reporter cells treated for 72 h with pomalidomide at various concentrations showed a maximum 6.9‐fold induction of Aγ‐HiBiT signal (EC 50 = 0.9 µM), but no toxicity up to 50 µM pomalidomide. Error bars indicate the standard deviation of N = 3 independent cultures. (L) Although differentiation alone increased globin expression and thus the Aγ‐HiBiT signal, the addition of pomalidomide to the differentiation medium resulted in an additional 7.7‐fold increase in Aγ‐HiBiT signals. Error bars indicate the standard deviation of N = 3 independent cultures. (M, N) A toxic compound (no surviving cells at 50 µM, CC 50 = 1.7 µM) did not induce Aγ‐HiBiT expression. Error bars indicate the standard deviation of N = 3 independent cultures. (O) The Aγ‐HiBiT reporter cells were sensitive to the solvent DMSO (CC 50 = 0.55% [v/v]).

Article Snippet: Primary antibodies recognized γ‐globin (sc‐21756; Santa Cruz Biotechnology), β‐globin (sc‐21757), and NPM1 (ab10530; Abcam).

Techniques: Positive Control, Derivative Assay, Reverse Transcription, Polymerase Chain Reaction, Expressing, Control, Solvent, Western Blot, High Performance Liquid Chromatography, Standard Deviation