OTX2 represses sister cell fate choices in the developing retina to promote photoreceptor specification

During vertebrate retinal development, subsets of progenitor cells generate progeny in a non-stochastic manner, suggesting that these decisions are tightly regulated. However, the gene-regulatory network components that are functionally important in these progenitor cells are largely unknown. Here we identify a functional role for the OTX2 transcription factor in this process. CRISPR/Cas9 gene editing was used to produce somatic mutations of OTX2 in the chick retina and identified similar phenotypes to those observed in human patients. Single cell RNA sequencing was used to determine the functional consequences OTX2 gene editing on the population of cells derived from OTX2-expressing retinal progenitor cells. This confirmed that OTX2 is required for the generation of photoreceptors, but also for repression of specific retinal fates and alternative gene regulatory networks. These include specific subtypes of retinal ganglion and horizontal cells, suggesting that in this context, OTX2 functions to repress sister cell fate choices

Pumilio directs deadenylation-associated translational repression of the cyclin-dependent kinase 1 activator RGC-32

Response gene to complement-32 (RGC-32) activates cyclin-dependent kinase 1, regulates the cell cycle and is deregulated in many human tumours. We previously showed that RGC-32 expression is upregulated by the cancer-associated Epstein-Barr virus (EBV) in latently infected B cells through the relief of translational repression. We now show that EBV infection of naïve primary B cells also induces RGC-32 protein translation. In EBV-immortalised cell lines, we found that RGC-32 depletion resulted in cell death, indicating a key role in B cell survival. Studying RGC-32 translational control in EBV-infected cells, we found that the RGC-32 3′untranslated region (3′UTR) mediates translational repression. Repression was dependent on a single Pumilio binding element (PBE) adjacent to the polyadenylation signal. Mutation of this PBE did not affect mRNA cleavage, but resulted in increased polyA tail length. Consistent with Pumilio-dependent recruitment of deadenylases, we found that depletion of Pumilio in EBV-infected cells increased RGC-32 protein expression and polyA tail length. The extent of Pumilio binding to the endogenous RGC-32 mRNA in EBV-infected cell lines also correlated with RGC-32 protein expression. Our data demonstrate the importance of RGC-32 for the survival of EBV-immortalised B cells and identify Pumilio as a key regulator of RGC-32 translation

The outcome of two or more HLA loci mismatched unrelated donor hematopoietic cell transplantation for acute leukemia: an ALWP of the EBMT study

A mismatched unrelated (MMUD) donor represents an alternative therapeutic option for patients who need allogeneic hematopoietic cell transplantation (allo-HCT) and do not have a human leukocyte antigen (HLA) matched donor. We studied outcomes of patients with acute leukemia transplanted from ≥2 HLA allele MMUD. The study population consisted of 465 patients. The median follow-up period was 63 and 75 months in the AML and ALL groups, respectively. The incidence of grade II-IV and grade III-IV acute (a) graft-versus-host disease (GVHD) during the first 100 days was 37% and 16%, respectively. Total and extensive chronic (c) GVHD rates at 2 years were 38% and 17%, respectively. In the entire population, the 5-year relapse incidence (RI), non-relapse mortality (NRM), leukemia-free survival (LFS), overall survival and refined GVHD-free, relapse-free survival (GRFS) was 33%, 31%, 37%, 41%, and 27%, respectively. In the multivariate analysis, HLA-DR mismatch was a poor prognostic factor, giving a significantly higher NRM [hazard ratio (HR), 1.67, p = 0.02]; poorer LFS (HR, 1.42, p = 0.03); OS (HR, 1.46, p = 0.03) and higher aGVHD grade II-IV (HR, 1.46, p = 0.05). In this study, allo-HCT from ≤6/8 HLA allele MMUD in acute leukemia patients resulted in acceptable LFS and refined GRFS. HLA-DR mismatch was a poor prognostic factor