SEC23A rescues SEC23B-deficient congenital dyserythropoietic anemia type II

Abstract

Congenital dyserythropoietic anemia type II (CDAII) results from loss-of-function mutations in <i>SEC23B</i>. In contrast to humans, SEC23B-deficient mice deletion do not exhibit CDAII but die perinatally with pancreatic degeneration. Here, we demonstrate that expression of the full SEC23A protein (the SEC23B paralog) from the endogenous regulatory elements of <i>Sec23b</i> completely rescues the SEC23B-deficient mouse phenotype. Consistent with these data, while mice with erythroid-specific deletion of either <i>Sec23a</i> or <i>Sec23b</i> do not exhibit CDAII, we now show that mice with erythroid-specific deletion of all four <i>Sec23</i> alleles die in mid-embryogenesis with features of CDAII and that mice with deletion of three <i>Sec23</i> alleles exhibit a milder erythroid defect. To test whether the functional overlap between the <i>SEC23</i> paralogs is conserved in human erythroid cells, we generated SEC23B-deficient HUDEP-2 cells. Upon differentiation, these cells exhibited features of CDAII, which were rescued by increased expression of SEC23A, suggesting a novel therapeutic strategy for CDAII.