In the absence of apoptosis, myeloid cells arrest when deprived of growth factor, but remain viable by consuming extracellular glucose

Cell Death Differ. 2019 Oct;26(10):2074-2085. doi: 10.1038/s41418-019-0275-z. Epub 2019 Feb 15.

Abstract

Withdrawal of the growth factor interleukin-3 (IL-3) from IL-3-dependent myeloid cells causes them to undergo Bax/Bak1-dependent apoptosis, whereas factor-deprived Bax-/-Bak1-/- cells remain viable, but arrest and shrink. It was reported that withdrawal of IL-3 from Bax-/-Bak1-/- cells caused decreased expression of the glucose transporter Glut1, leading to reduced glucose uptake, so that arrested cells required Atg5-dependent autophagy for long-term survival. In other cell types, a decrease in Glut1 is mediated by the thioredoxin-interacting protein (Txnip), which is induced in IL-3-dependent myeloid cells when growth factor is removed. We mutated Atg5 and Txnip by CRISPR/Cas9 and found that Atg5-dependent autophagy was not necessary for the long-term viability of cycling or arrested Bax-/-Bak1-/- cells, and that Txnip was not required for the decrease in Glut1 expression in response to IL-3 withdrawal. Surprisingly, Atg5-deficient Bax/Bak1 double mutant cells survived for several weeks in medium supplemented with 10% fetal bovine serum (FBS), without high concentrations of added glucose or glutamine. When serum was withdrawn, the provision of an equivalent amount of glucose present in 10% FBS (~0.5 mM) was sufficient to support cell survival for more than a week, in the presence or absence of IL-3. Thus, Bax-/-Bak1-/- myeloid cells deprived of growth factor consume extracellular glucose to maintain long-term viability, without a requirement for Atg5-dependent autophagy.

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Autophagy-Related Protein 5 / deficiency
  • Autophagy-Related Protein 5 / genetics
  • Autophagy-Related Protein 5 / metabolism
  • Cell Survival / physiology
  • Gene Knockout Techniques
  • Glucose / metabolism*
  • Glucose / pharmacology*
  • Interleukin-3 / deficiency*
  • Interleukin-3 / metabolism
  • Mice
  • Myeloid Cells / cytology*
  • Myeloid Cells / metabolism*
  • bcl-2 Homologous Antagonist-Killer Protein / deficiency
  • bcl-2 Homologous Antagonist-Killer Protein / genetics
  • bcl-2 Homologous Antagonist-Killer Protein / metabolism
  • bcl-2-Associated X Protein / deficiency
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism

Substances

  • Atg5 protein, mouse
  • Autophagy-Related Protein 5
  • Bak1 protein, mouse
  • Bax protein, mouse
  • Interleukin-3
  • bcl-2 Homologous Antagonist-Killer Protein
  • bcl-2-Associated X Protein
  • Glucose