LSD1 inhibition ameliorates congenital dyserythropoietic anemia type II.

Abstract

Congenital dyserythropoietic anemia type II (CDAII) is an autosomal recessive disease resulting from loss-of-function mutations in <i>SEC23 homolog B</i> (<i>SEC23B</i>). We have previously shown that increased expression of SEC23A, a paralogous protein for SEC23B, rescues the CDAII erythroid defect. Here, we generated a human erythroid cell line that expresses enhanced green fluorescent protein (eGFP) from the endogenous <i>SEC23A</i> locus and performed a small-molecule screen to identify compounds that increased SEC23A-eGFP abundance. The top compound passing all filters was an inhibitor of lysine-specific demethylase 1 (LSD1). We found that LSD1 inhibition with RN1 resulted in increased SEC23A expression in erythroid cells derived from human hematopoietic stem and progenitor cells (HSPCs) at doses that did not impair erythroid cell growth or differentiation and rescued the erythroid defect resulting from <i>SEC23B</i> deletion. Genetic down-regulation of <i>LSD1</i> led to a marked increase in <i>SEC23A</i> mRNA expression in HSPC-derived erythroid cells. Deletion of <i>Lsd1</i> in mouse erythroid cells resulted in increased <i>Sec23a</i> expression, and RN1 treatment ameliorated the erythroid defect observed in a CDAII mouse model. Mechanistically, we found that LSD1 occupied a sequence in the <i>SEC23A</i> promoter, repressing <i>SEC23A</i> transcription. Deletion of the promotor sequence occupied by LSD1 resulted in increased SEC23A expression and amelioration of CDAII. These findings highlight that LSD1 represses <i>SEC23A</i> transcription and that LSD1 inhibition results in de-repression of <i>SEC23A</i> expression and amelioration of the CDAII erythroid defect, suggesting promising therapeutic strategies for CDAII.