Mitofusin-2 mediates mitochondria-lysosomal membrane contacts and is required for erythropoiesis. (A) BloodSpot expression profiles for TFR2 and MCOLN1, using DMAP dataset. (B) BloodSpot expression correlation analysis from DMAP dataset listing expression correlation coefficients for the most correlated genes to MCOLN1. (C) Immunoblot documentation of Mitofusin-2 knockdown in erythroid progenitors transduced with lentiviral shRNA constructs. (D) Transmission electron microscopy of erythroid progenitors transduced with lentiviral shRNA constructs (arrows denote mitochondria in direct contact with MVB/lysosomes). (E) Ultrastructural quantitation of mitochondria-MVB/lysosome membrane contacts in transduced erythroid progenitors as in (D) (total cells counted = 15 per group; *P < .05. (F) Total heme content in erythroid progenitors (top), K562 cells (middle), and HUDEP-2 cells (bottom) transduced with lentiviral shRNA constructs (top) (n = 4 per group; **P < .01, ***P < .001). (G) Flow cytometry (left) of progenitors transduced as in (D) and cultured 4 days in erythroid medium; summary of flow cytometry experiments on transduced progenitors (right) (n = 3; *P < .05).