Recapitulation of anti-aging phenotypes by global overexpression of PTEN in mice

Abstract

The PTEN gene negatively regulates the oncogenic PI3K-AKT pathway by encoding a lipid and protein phosphatase that dephosphorylates lipid phosphatidylinositol-3,4,5-triphosphate (PIP₃) resulting in the inhibition of PI3K and downstream inhibition of AKT. Overexpression of PTEN in mice leads to a longer lifespan compared to control littermates, although the mechanism is unknown. Here, we provide evidence that young adult PTENOE mice exhibit many characteristics shared by other slow-aging mouse models, including those with mutations that affect GH/IGF1 pathways, calorie-restricted mice, and mice treated with anti-aging drugs. PTENOE white adipose tissue (WAT) has increased UCP1, a protein linked to increased thermogenesis. WAT of PTENOE mice also shows a change in polarization of fat-associated macrophages, with elevated levels of arginase 1 (Arg1, characteristic of M2 macrophages) and decreased production of inducible nitric oxide synthase (iNOS, characteristic of M1 macrophages). Muscle and hippocampus showed increased expression of the myokine FNDC5, and higher levels of its cleavage product irisin in plasma, which has been linked to increased conversion of WAT to more thermogenic beige/brown adipose tissue. PTENOE mice also have an increase, in plasma and liver, of GPLD1, which is known to improve cognition in mice. Hippocampus of the PTENOE mice has elevation of both BDNF and DCX, indices of brain resilience and neurogenesis. These changes in fat, macrophages, liver, muscle, hippocampus, and plasma may be considered "aging rate indicators" in that they seem to be consistently changed across many of the long-lived mouse models and may help to extend lifespan by delaying many forms of late-life illness. Our new findings show that PTENOE mice can be added to the group of long-lived mice that share this multi-tissue suite of biochemical characteristics.

Keywords: Adipose tissue; Aging; Brain-derived neurotrophic factor (BDNF); Doublecortin (DCX)); Fibronectin type III domain-containing protein 5 (FNDC5)/IRISIN; Glycosylphosphatidylinositol-specific phospholipase D1 (GPLD1); Hippocampus; Liver; Macrophage; Phosphatase and tensin homolog (PTEN); Slow-aging mice; Uncoupling protein 1 (UCP1).

Fig. 1

Effects of PTEN on levels of IGF-1 in plasma, body length, body mass, and adipose tissue mass. A IGF-1 protein was measured by ELISA assay on plasma samples of 24-week-old wild-type littermate control mice (WT) and PTENOE mice (n = 13–18 per group). In each panel, data are shown as mean ± SEM. ****p < 0.0001 by two-way ANOVA. B, C Body length (from nose to tail tip) and femur length were measured in 16-week-old mice. (n = 15–19). E, F, G Mass of BAT, ING WAT, and PG WAT in 16-week-old mice (n = 15–19). Asterisks in panels without interaction effect indicate significance for genotype or sex effect in two-way ANOVA: ****p < 0.0001; ***p < 0.001; **p < 0.01, * p < 0.05. Asterisks in D reflect t-tests done separately in each sex

Fig. 2

Expression of UCP1 in adipose tissue of PTENOE mice. A, C, E Cell lysates were prepared from adipose tissues of 16-week-old WT and PTENOE mice (n = 9–15). Protein levels of UCP1 (brown and beige fat marker) were measured by western blotting. Representative gel images showing UCP1 in brown (A), inguinal (C), and perigonadal adipose tissue (E). B, D, F Protein quantification data normalized to β-actin and expressed as fold change compared with WT control (defined as 1.0). Data are means ± SEM. **p < 0.01; ***p < 0.001; ****p < 0.0001 versus WT

Fig. 3

Expression of M2 macrophage marker Arg1 in adipose tissue of PTENOE mice. A, C, E Cell lysates were prepared from adipose tissues of 16-week-old wild-type littermate control mice (WT) and PTENOE mice (n = 7–10). Protein levels of Arg1 (M2 macrophage marker) were then measured by western blotting. Representative gel images showing Arg1 in brown (A), inguinal (C), perigonadal adipose tissue (E). B, D, F Protein quantification data normalized to β-actin and expressed as fold change compared with WT control (defined as 1.0). Data are means ± SEM. *p < 0.05 versus WT

Fig. 4

Expression of M1 macrophage marker in adipose tissue of PTENOE mice. A, C, E Cell lysates were prepared from adipose tissues of 16-week-old wild-type littermate control mice (WT) and PTENOE mice (n = 7–10). Protein levels of iNOS (M1 macrophage marker) were then measured by western blotting. Representative gel images showing iNOS in brown adipose tissue (A), inguinal adipose tissue (C), and perigonadal adipose tissue (E). B, D, F Protein quantification data normalized to β-actin and expressed as fold change compared with WT control (defined as 1.0). Data are means ± SEM. *p < 0.05 versus WT

Fig. 5

Expression of FNDC5 in gastrocnemius muscle and hippocampus and irisin levels in plasma of PTENOE mice. A Cell lysates were prepared from gastrocnemius muscle of 16-week-old wild-type littermate control mice (WT) and PTENOE mice (n = 7–10). Protein levels of FNDC5 were measured by western blotting. Representative gel images are shown. B Protein quantification data normalized to β-actin and expressed as fold change compared with WT control (defined as 1.0). Data are means ± SEM. **p < 0.01 versus WT. C Representative gel images showing FNDC5 in hippocampus. D Protein quantification data for hippocampus (n = 4–6). Data are means ± SEM. *p < 0.05; ** p < 0.01 versus WT. E Irisin measured by ELISA assay on plasma samples of 16-week-old wild-type littermate control mice (WT) and long-lived mice (PTENOE). Data are shown as mean ± SEM for each group (n = 13–15). *p < 0.05 for genotype effect by two-way ANOVA

Fig. 6

Effects of PTEN on GPLD1 in liver, hippocampus, and plasma. A, C Cell lysate was prepared from liver and hippocampus of 16-week-old wild-type littermate control mice (WT) and PTENOE mice. Protein levels of GPLD1 were then measured by western blotting. Representative gel images showing GPLD1 in liver tissue (n = 11) (A), hippocampus tissue (n = 6 per group) (C). B, D Protein quantification data normalized to β-actin and expressed as fold change compared with WT control (defined as 1.0). *p < 0.05 versus WT. E GPLD1 protein was measured by ELISA assay on plasma samples of 16-week-old mice. Data are shown as mean ± SEM for each group (n = 6). **p < 0.01 for genotype effect by two-way ANOVA

Fig. 7

Expression of BDNF and doublecortin (DCX) in hippocampus of PTENOE mice. A Cell lysates were prepared from hippocampus of 16-week-old wild-type littermate control mice (WT) and PTENOE mice. Protein levels of BDNF were measured by western blotting. Representative gel images are shown. B Protein quantification data normalized to β-actin and expressed as fold change compared with WT control (defined as 1.0). N = 4–6 mice for each group (WT and PTENOE). Data are means ± SEM. ****p < 0.0001 versus WT. C Representative gel images showing doublecortin (DCX) in hippocampus. D Protein quantification data for hippocampus. Data are shown as mean ± SEM for each group. **** p < 0.0001 versus WT