title: Differential effects of p27 in regulation of beta-cell mass during development, neonatal period, and adult life.
abstract: beta-Cell cycle progression and proliferation are critical to maintain beta-cell mass in adult mice. Of the cell cycle inhibitors, p27Kip1 is thought to be the primary modulator of the proliferative status in most cell types. p27 plays a role in beta-cell adaptation in genetic models of insulin resistance. To study the role of p27 in beta-cells during physiological conditions and at different stages of beta-cell differentiation, we studied mice deficient of or overexpressing p27. Experiments in p27-deficient mice showed improved glucose tolerance and hyperinsulinemia. These changes were associated with increased islet mass and proliferation. The experiments overexpressing p27 in beta-cells were performed using a doxycycline-inducible model. Interestingly, overexpression of p27 for 16 weeks in beta-cells from adult mice had no effect on glucose tolerance, beta-cell mass, or proliferation. In contrast, induction of p27 expression during beta-cell development or early neonatal period resulted in severe glucose intolerance and reduced beta-cell mass by decreased proliferation. These changes were reversible upon discontinuation of doxycycline. These experiments suggest that p27 is a critical molecule for beta-cell proliferation during beta-cell development and early postnatal life but not for maintenance of adult mass.
authors.affiliation: Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8127, St. Louis, MO 63110, USA.
authors.forename: Latif
authors.initials: L
authors.lastname: Rachdi
authors.forename: Norman
authors.initials: N
authors.lastname: Balcazar
authors.forename: Lynda
authors.initials: L
authors.lastname: Elghazi
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Barker
authors.forename: Irina
authors.initials: I
authors.lastname: Krits
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kiyokawa
authors.forename: Ernesto
authors.initials: E
authors.lastname: Bernal-Mizrachi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001786:Blood Glucose / Q000378:metabolism*; D002455:Cell Division; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D006706:Homeostasis; D050417:Insulin-Secreting Cells / Q000166:cytology*; D007515:Islets of Langerhans / Q000033:anatomy & histology* / Q000254:growth & development; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout
chemical_list: D001786:Blood Glucose; D050760:Cyclin-Dependent Kinase Inhibitor p27