DNA Damage Does Not Cause BrdU Labeling of Mouse or Human β-Cells

Diabetes. 2019 May;68(5):975-987. doi: 10.2337/db18-0761. Epub 2019 Mar 4.

Abstract

Pancreatic β-cell regeneration, the therapeutic expansion of β-cell number to reverse diabetes, is an important goal. Replication of differentiated insulin-producing cells is the major source of new β-cells in adult mice and juvenile humans. Nucleoside analogs such as BrdU, which are incorporated into DNA during S-phase, have been widely used to quantify β-cell proliferation. However, reports of β-cell nuclei labeling with both BrdU and γ-phosphorylated H2A histone family member X (γH2AX), a DNA damage marker, have raised questions about the fidelity of BrdU to label S-phase, especially during conditions when DNA damage is present. We performed experiments to clarify the causes of BrdU-γH2AX double labeling in mouse and human β-cells. BrdU-γH2AX colabeling is neither an age-related phenomenon nor limited to human β-cells. DNA damage suppressed BrdU labeling and BrdU-γH2AX colabeling. In dispersed islet cells, but not in intact islets or in vivo, pro-proliferative conditions promoted both BrdU and γH2AX labeling, which could indicate DNA damage, DNA replication stress, or cell cycle-related intrinsic H2AX phosphorylation. Strategies to increase β-cell number must not only tackle the difficult challenge of enticing a quiescent cell to enter the cell cycle, but also achieve safe completion of the cell division process.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Bromodeoxyuridine / chemistry*
  • Bromodeoxyuridine / metabolism*
  • Cell Cycle / drug effects
  • Cell Cycle / genetics
  • Cell Proliferation / drug effects
  • Cell Proliferation / genetics
  • DNA / metabolism
  • DNA Damage / drug effects
  • DNA Damage / genetics
  • Humans
  • Insulin-Secreting Cells / drug effects
  • Insulin-Secreting Cells / metabolism*
  • Mice

Substances

  • DNA
  • Bromodeoxyuridine