Journal: Blood
Article Title: Metabolic Adaptation of Regenerative Hematopoiesis Depends on Docking-Independent Mitochondrial Connexin-43
doi: 10.1182/blood.2024028079
Figure Lengend Snippet: (A) Graphical representation of Cx43 full length and the truncation mutation, cys-less and Δ CT 257 incorporated into EF1α-MCS-IRES-dsRED retroviral vector. (B-I) WT and Cx43 Δ/Δ HSC transduced with constructs coding for different forms of Cx43 (FL, cys-less or ΔCT 257 ) and analyzed. Representative immunofluorescence image (B) and quantification (C) depicting OGDH expression (red). Nuclei were counterstained with DAPI (blue). Dots show individual cells. (D) ATP levels in WT and Cx43 Δ/Δ BM HSC containing different Cx43 constructs (FL, cys-less or ΔCT 257 ). Data point depict individual experiments. (E) Immunofluorescence staining of mito-Dendra2 + (green) and Mfn2 (red) and (F) quantification depicting Mfn2 expression. Nuclei were counterstained with DAPI (blue). Dots depict individual cells. (G) Representative immunofluorescence staining of Dendra2 + mitochondria (green) and pDrp1 (S616) (red), and (H) quantification of pDrp1 (S616). Nuclei were counterstained with DAPI (blue). Dots depict individual cells. (I) Mitochondrial calcium levels (Rhod-2 AM) in WT and Cx43 Δ/Δ HSC containing empty vector or different Cx43 constructs (FL, cys-less or ΔCT 257 ). n= 4 independent experiments. (J) Schema depicting transplantation of WT and Cx43 Δ/Δ HSC containing different Cx43 constructs (FL, cys-less or ΔCT 257 ) into sub-lethally irradiated (2.5 Gy) congenic NOD- scid IL2Rgamma null , NOD- scid IL2Rg null mice and analyzed as indicated. (K) Peripheral blood count of mito-Dendra2 + /dsRED + leukocytes, neutrophils, and CD11b cells in NSG mice at indicated time post-transplant (*p<0.05, **p<0.01, ***p<0.001 vs Cx43 Δ/Δ Empty vector). Three independent experiments with 4 mice each were performed. (L) BM count for LT-HSC, MPP2, and LSK cell in NSG mice at indicated time post-transplant. Each data point depicts individual mice, and three independent experiments were performed. (M) HSC-enriched LSK BM cells from WT and Cx43 Δ/Δ chimeric mice (49 days post transplantation) containing different Cx43 constructs (FL, cys-less or ΔCT 257 ) were FACS sorted and mitochondrial OCR was measured by Seahorse extracellular flux analyzer. (N) Quantification summary of mitochondrial OCR (basal, maximal, ATP production, and Spare Respiratory Capacity; SRC) in WT and Cx43 Δ/Δ HSC/MPP containing different Cx43 constructs. All data points depict a pool of 4 mice HSC/MPP and three experimental replicates were performed. (O) WT and Cx43 Δ/Δ mito-Dendra2 + HSC transduced with constructs coding for different forms of Cx43 (FL, cys-less or Δ CT 257 ) were co-cultured over WT BM stroma for 16h. Flow cytometry histogram overlay (left) and quantification (right) demonstrate transfer of mitochondria from HSC/MPP transduced with Cx43 constructs to BM stromal cells. n= 4 independent experiments. Data represented as mean ± SEM. All immunofluorescence quantification data represent pools of 2–3 independent experiments. Scale bar, 2 µm. Statistical p values were generated by unpaired, two-tailed t test except in panel C, F, G where one-way ANOVA with Tukey’s multiple comparisons test was used. *p<0.05, **p<0.01, ***p<0.001.
Article Snippet: Dots depict individual cells. (D) Left: Representative immunofluorescence image showing mitochondria (green) and Parkin (red) staining in WT and Cx43 Δ/Δ dividing HSC. (i) Imaris reconstructed mitochondrial surface (green) and Parkin spots was used to define inside (reconstructed big red spot; white arrow) and outside (reconstructed small pink spots) Parkin to mitochondria surface.
Techniques: Activity Assay, Mutagenesis, Retroviral, Plasmid Preparation, Transduction, Construct, Immunofluorescence, Expressing, Staining, Transplantation Assay, Irradiation, Cell Culture, Flow Cytometry, Generated, Two Tailed Test