ALDH expression characterizes G1-phase proliferating beta cells during pregnancy.

Area of Science:

• Cell Biology
• Endocrinology
• Stem Cell Biology

Background:

• Aldehyde dehydrogenase (ALDH) activity is a marker for progenitor and stem cells.
• ALDH activity has been identified in pancreatic progenitor cells but not previously studied in beta cells.
• Pregnancy induces significant physiological changes in the pancreas.

Purpose of the Study:

• To investigate aldehyde dehydrogenase (ALDH) activity and Aldefluor fluorescence in pancreatic beta cells during pregnancy.
• To determine the cell cycle phase at which beta cells exhibit ALDH activity.
• To explore the utility of Aldefluor staining for identifying and analyzing proliferating beta cells.

Main Methods:

• Aldefluor staining to detect ALDH activity in mouse pancreatic beta cells.
• Co-staining with proliferation markers: Ki-67, phosphohistone3 (PHH3), and Bromodeoxyuridine (BrdU).
• Immunofluorescence microscopy to analyze co-localization of Aldefluor signal with proliferation markers and insulin.

Main Results:

• A dynamic increase in Aldefluor-positive beta cells was observed during pregnancy.
• Nearly all Aldefluor-positive beta cells were also positive for Ki-67, indicating active proliferation.
• Aldehluor positivity was primarily observed in the G1 phase of the cell cycle, with downregulation upon entering S phase.

Conclusions:

• Beta cells activate ALDH and become Aldefluor-positive upon entering the G1 phase of the cell cycle during pregnancy.
• Aldefluor staining provides a novel method for the isolation and analysis of proliferating beta cells.
• Caution is advised when interpreting Aldefluor lineage-tracing data in the pancreas due to dynamic ALDH activity changes.