Research ArticlePhysiology

Ca2+ concentration–dependent premature death of igfbp5a−/− fish reveals a critical role of IGF signaling in adaptive epithelial growth

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Science Signaling  18 Sep 2018:
Vol. 11, Issue 548, eaat2231
DOI: 10.1126/scisignal.aat2231

Stressing out about low Ca2+

Under low Ca2+ conditions, an epithelial cell population in zebrafish known as NaR cells proliferate so that they can take up more Ca2+. Liu et al. found that Igf-binding protein 5A (Igfbp5a) was required for this adaptive proliferation and for survival under low Ca2+ conditions. The defect in NaR adaptive proliferation in igfbp5a−/− zebrafish was rescued by expression of wild-type human or zebrafish IGFBP5 but not two cancer-associated IGFBP5 mutants. Mice deficient in the various IGFBPs lack obvious phenotypes, and these results reveal the importance of using the appropriate physiological conditions to determine the function of IGFBPs.

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