Differential expression of adenine nucleotide converting enzymes in mitochondrial intermembrane space: a potential role of adenylate kinase isozyme 2 in neutrophil differentiation

PLoS One. 2014 Feb 25;9(2):e89916. doi: 10.1371/journal.pone.0089916. eCollection 2014.

Abstract

Adenine nucleotide dynamics in the mitochondrial intermembrane space (IMS) play a key role in oxidative phosphorylation. In a previous study, Drosophila adenylate kinase isozyme 2 (Dak2) knockout was reported to cause developmental lethality at the larval stage in Drosophila melanogaster. In addition, two other studies reported that AK2 is a responsible gene for reticular dysgenesis (RD), a human disease that is characterized by severe combined immunodeficiency and deafness. Therefore, mitochondrial AK2 may play an important role in hematopoietic differentiation and ontogenesis. Three additional adenine nucleotide metabolizing enzymes, including mitochondrial creatine kinases (CKMT1 and CKMT2) and nucleoside diphosphate kinase isoform D (NDPK-D), have been found in IMS. Although these kinases generate ADP for ATP synthesis, their involvement in RD remains unclear and still an open question. In this study, mRNA and protein expressions of these mitochondrial kinases were firstly examined in mouse ES cells, day 8 embryos, and 7-week-old adult mice. It was found that their expressions are spatiotemporally regulated, and Ak2 is exclusively expressed in bone marrow, which is a major hematopoietic tissue in adults. In subsequent experiments, we identified increased expression of both AK2 and CKMT1 during macrophage differentiation and exclusive production of AK2 during neutrophil differentiation using HL-60 cells as an in vitro model of hematopoietic differentiation. Furthermore, AK2 knockdown specifically inhibited neutrophil differentiation without affecting macrophage differentiation. These data suggest that AK2 is indispensable for neutrophil differentiation and indicate a possible causative link between AK2 deficiency and neutropenia in RD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylate Kinase / metabolism*
  • Animals
  • Azo Compounds
  • Blotting, Western
  • Cell Differentiation / physiology*
  • Cell Line, Tumor
  • Creatine Kinase / metabolism
  • Creatine Kinase, Mitochondrial Form
  • DNA Primers / genetics
  • Embryonic Stem Cells
  • Gene Knockdown Techniques
  • Humans
  • Leukopenia / enzymology*
  • Mice
  • Mitochondrial Membranes / metabolism*
  • Neutrophils / enzymology*
  • Neutrophils / physiology
  • Reactive Oxygen Species / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Rosaniline Dyes
  • Severe Combined Immunodeficiency / enzymology*

Substances

  • Azo Compounds
  • DNA Primers
  • Reactive Oxygen Species
  • Rosaniline Dyes
  • CKMT1A protein, human
  • CKMT2 protein, human
  • Creatine Kinase
  • Creatine Kinase, Mitochondrial Form
  • Adenylate Kinase
  • adenylate kinase 2
  • coomassie Brilliant Blue
  • ponceau S

Supplementary concepts

  • Reticular dysgenesis

Grants and funding

This work was partly supported by a Grant-in-Aid for Young Scientists (B) 13278393) from the Ministry of Education, Science, Sports and Culture, a grant for the special scientific research program aimed at the improvement of QOL (Quality of Life) via oral function in collaboration with universities from the Ministry of Education, Culture, Sports, Science, and Technology, and a research grant supported by Kojinkai Foundation, and the President discretion research budget of the University of Tokushima. No additional external funding received for this study. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.