Unknown,Transcriptomics,Genomics,Proteomics

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AK2 deficiency affects human hematopoiesis

ABSTRACT: Reticular dysgenesis (RD) is a human Severe Combined Immunodeficiency mainly characterized by a profound neutropenia and lymphopenia. This pathology is due to mutations in the adenylate kinase 2 (AK2) gene, resulting in the loss of AK2 protein expression. AK2 is a mitochondrial protein, which regulates the homeostasis of cellular adenine nucleotides by converting ADP into ATP and AMP. Using a RNA interference strategy, we dissected the role of AK2 during the commitment of hematopoietic progenitors towards the lymphoid or myeloid lineage. Our results demonstrated that AK2 knock-down progenitors have reduced proliferative and survival capacity and differentiation toward the lymphoid or granulocytic lineage is abrogated. In this report, we also highlighted that AK2 signaling pathway is essential to control energy production and to maintain the integrity of all mitochondrial functions. This steady state may be disturbed in RD patients leading to a blockade of the differentiation process.

ORGANISM(S): Homo sapiens

SUBMITTER: Nicolas Cagnard

PROVIDER: E-MTAB-2680 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Growth factor independent 1 (Gfi1) is a transcriptional repressor originally identified as a common integration site in Moloney-murine-leukemia-virus-induced T-cell leukemia. Gfi1-/- mice display increased apoptosis of developing thymocytes and T lymphopenia; however, there are contradictory reports of the absolute number of Gfi1-/- early T lineage progenitors. We used floxed alleles of Gfi1 crossed to various T-cell-specific Cre transgenes to map the requirements for Gfi1 during lymphoid priming and development. We show that Gfi1 is necessary for the proper formation and function of both lymphoid-primed multipotent progenitors and early T lineage progenitors. These defects correlate with a global inability of Gfi1-/- progenitors to enforce the activation of lymphoid genes including IL7R, Rag1, Flt3 and Notch1. Forced expression of intracellular Notch1 fails to rescue the Gfi1-/- defective lymphoid gene signature or Gfi1-/- T cell development. Instead, activation of Notch1 in Gfi1-/- cells results in a potent synthetic lethal phenotype that is most dramatic in immature thymocytes, but absent in mature peripheral T cells where developmental transcriptional programs are silent. Moreover, we find that the requirement for Gfi1-transcriptional integration of Notch-driven lymphoid transcriptional programs is cell autonomous. Our data indicate that Gfi1 is required at multiple independent stages of lymphoid development. In hematopoietic progenitors Gfi1 is necessary to integrate Notch1 signaling, mediate lymphoid priming, the formation of early T lineage progenitors and subsequent T lineage commitment. Lineage negative cells were purified by magnetic beads from RosaCreERT2 Gfi1 ex4-5 floxed mice and an activated Notch1 signal was introduced using a GFP+ retroviral vector. GFP+ progenitors were FACS-sorted and cultured in semi-solid media for one week to allow sufficient time to to instruct lymphoid differentiation, then replated in 1uM 4-OHT or EtOH control. After an additional 7 days, CFU were disrupted and RNA was isolated for global gene expression using microarrays.

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AK2 deficiency affects human hematopoiesis

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