Decreased senescence marker protein-30 could be a factor that contributes to the worsening of glucose tolerance in normal aging.

In our recent paper, we proposed that senescence marker protein-30 (SMP30) could be a novel molecule which was involved in an impairment of β-cell function with aging. SMP30 knockout (KO) mice and wild-type (WT) mice were fed a standard diet (SD) or a high fat diet (HFD) for 8 weeks from 7 weeks of age. In an intraperitoneal glucose tolerance test at 15 weeks of age, blood glucose levels in SD-fed KO mice were significantly increased by 25% at 30 min after glucose administration compared to SD-fed WT mice. Insulin levels in SD-fed KO mice were significantly decreased by 37% at 30 min postglucose compared to SD-fed WT mice. Interestingly, an insulin tolerance test showed a greater glucose lowering effect in SD-fed KO mice. Morphometric analysis revealed no differences in the degree of HFD-induced compensatory increase in β-cell mass and proliferation. Collectively, these data indicate that impairment of the early phase of insulin secretion underlies glucose intolerance in KO mice. Decreased SMP30 may contribute to the worsening of glucose tolerance that occurs in normal aging.