Short Chain Fatty Acids and p38 in the Induction of Embryonic/Fetal Globin Genes During Definitive Erythropoiesis.

Abstract 460 Augmentation of fetal hemoglogin (HbF) is therapeutically desirable in β –globin gene disorders, such as sickle cell anemia and β-thalassemia. Short chain fatty acids (SCFAs) can augment embryonic/fetal β-type globin gene expression in vivo and in vitro during adult definitive erythropoiesis (EryD), but the underlying molecular mechanisms are not well understood. p38 signaling, triggered by stress erythropoiesis, has been implicated in the induction of fetal globin gene expression. Here, we examined p38 signaling and its effects using a murine primary cell model of EryD, isolated from fetal liver. This model overcomes some limitations of previously used transformed or long-term primary cell models, and has afforded complementary data. E14.5 erythroid fetal cells (eFLCs) were examined at harvest and after culture in insulin and erythropoietin (‘ins/EPO9) with or without the SCFA butyrate, and in the presence or absence of p38 inhibitors SB 203580, SB 202190, PD 169316 at concentrations of 0-50 μM for up to 72 hours. Western blots showed that p38 phosphorylation was constitutive at harvest and preserved in cultures with ins/EPO, but was diminished by half after concurrent culture in PD169316. Embryonic globin gene expression, ((βH1+eY)/(βH1+eY+βMAJ) × 100), was analyzed by real-time PCR, normalized to 18S expression. Embryonic globin gene induction, relative to maximal expression at 72 hours in butyrate with ins/EPO, was blocked in a dose dependent manner by all inhibitors of p38 signaling, at 10-30% of maximal induction when cultured in 50 mM of any inhibitor. Primary transcripts from the adult β-globin gene, βmaj, were likewise diminished by p38 inhibition, with a median level of 8.3% and 4.0% of maximal transcript in ins/EPO and butyrate & ins/EPO respectively after culture for 72 hours in 50 μM PD 169316 (n=3, p Disclosures: No relevant conflicts of interest to declare.