Evidence of a developmental origin for β-cell heterogeneity using a dual lineage-tracing technology

The Cre/loxP system has been used extensively in mouse models with a limitation of one lineage at a time. Differences in function and other properties among populations of adult beta-cells is termed beta-cell heterogeneity, which was recently associated with diabetic phenotypes. Nevertheless, the presence of a developmentally derived beta-cell heterogeneity is unclear. Here, we have developed a novel dual lineage-tracing technology, using a combination of two recombinase systems, Dre/RoxP and Cre/LoxP, to independently trace green fluorescent Pdx1-lineage cells and red fluorescent Ptf1a-lineage cells in the developing and adult mouse pancreas. We detected a few Pdx1(+)/Ptf1a(-) lineage cells in addition to the vast majority of Pdx1(+)/Ptf1a(+) lineage cells in the pancreas. Moreover, Pdx1(+)/Ptf1a(+) lineage beta-cells had fewer Ki-67(+) proliferating beta-cells, and expressed higher mRNA levels of insulin, Glut2, Pdx1, MafA and Nkx6.1, but lower CCND1 and CDK4 levels, compared with Pdx1(+)/ Ptf1a(-) lineage beta-cells. Furthermore, more TSQ-high, SSC-high cells were detected in the Pdx1(+)Ptf1a(+) lineage population than in the Pdx1(+)Ptf1a(-) lineage population. Together, these data suggest that differential activation of Ptf1a in the developing pancreas may correlate with this beta-cell heterogeneity.