Methionine aminopeptidase 2 is required for HSC initiation and proliferation

Abstract

In a chemical screening, we tested the antiangiogenic effects of fumagillin derivatives and identified fumagillin as an inhibitor of definitive hematopoiesis in zebrafish embryos. Fumagillin is known to target methionine aminopeptidase II (MetAP2), an enzyme whose function in hematopoiesis is unknown. We investigated the role of MetAP2 in hematopoiesis by using zebrafish embryo and human umbilical cord blood models. Zebrafish metap2 was expressed ubiquitously during early embryogenesis and later in the somitic region, the caudal hematopoietic tissue, and pronephric duct. metap2 was inhibited by morpholino and fumagillin treatment, resulting in increased mpo expression at 18 hours postfertilization and reduced c-myb expression along the ventral wall of dorsal aorta at 36 hours postfertilization. It also disrupted intersegmental vessels in Tg-(fli1:gfp) embryos without affecting development of major axial vasculatures. Inhibition of MetAP2 in CB CD34 ؉ cells by fumagillin had no effect on overall clonogenic activity but significantly reduced their engraftment into immunodeficient nonobese diabetes/severe combined immunodeficiency mice.

Inhibition of endothelial ERK signalling by Smad1/5 is essential for haematopoietic stem cell emergence

“…However, the exact role of ERK in HSC development was still controversial 5,27 . To clarify this, we first identified the timing of ERK action on HSC emergence.…”

Suppression of inflammation in a mouse model of rheumatoid arthritis using targeted lipase-labile fumagillin prodrug nanoparticles

“…Although both MetAP-1 and MetAP-2 have common activity and substrates, MetAP-2 is upregulated during cellular proliferation [9] and has greater efficiency (1000-fold) in catalyzing methionine removal from certain proteins such as glyceraldehydes-3-phosphate dehydrogenase, a key glycolytic enzyme involved in the initiation of apoptosis [10]. Recent evidence suggests that MetAP-2 inhibition by fumagillin perturbed angiogenesis in zebrafish embryos, likely through the modulation of the noncanonical Wnt pathway signaling and erk1/2 phosphorylation, whose level is strictly regulated during angiogenesis [11,12]. However the exact mechanism by which fumagillin exerts its antiangiogenic effect remains undefined.…”

Functions of idh1 and its mutation in the regulation of developmental hematopoiesis in zebrafish

“…The zidh amplification products were cloned into pGEM-T Easy Vector (Promega) and used as template to generate antisense or sense (Shi and Leung, unpublished) digoxigenin-labeled RNA probes. Whole-mount in situ hybridization (WISH) of zebrafish embryos were performed as previously described 32,33 using probes for zidh1, zidh2, scl, lmo2, pu.1, l-plastin, mpo, mpeg1, gata1, gata2, ahe1, cebpa, c-myb, rag1, efnb2a, and flt4. Probe for runx1 was a generous gift from Dr David Traver (University of California, San Diego).…”

“…33 Briefly, dechorionated wild-type or transgenic embryos at the desired stage were collected and rinsed in E3 solution, digested with 0.05% trypsin-EDTA solution (Invitrogen) for 15 minutes at 28°C, and then completely dissociated to single-cell suspension by pipetting. CaCl 2 (2 mM) was added to terminate the digestion.…”