Loss of periostin occurs in aging adipose tissue of mice and its genetic ablation impairs adipose tissue lipid metabolism

Abstract

Remodeling of the extracellular matrix is a key component of the metabolic adaptations of adipose tissue in response to dietary and physiological challenges. Disruption of its integrity is a well-known aspect of adipose tissue dysfunction, for instance, during aging and obesity. Adipocyte regeneration from a tissue-resident pool of mesenchymal stem cells is part of normal tissue homeostasis. Among the pathophysiological consequences of adipogenic stem cell aging, characteristic changes in the secretory phenotype, which includes matrix-modifying proteins, have been described. Here, we show that the expression of the matricellular protein periostin, a component of the extracellular matrix produced and secreted by adipose tissue-resident interstitial cells, is markedly decreased in aged brown and white adipose tissue depots. Using a mouse model, we demonstrate that the adaptation of adipose tissue to adrenergic stimulation and high-fat diet feeding is impaired in animals with systemic ablation of the gene encoding for periostin. Our data suggest that loss of periostin attenuates lipid metabolism in adipose tissue, thus recapitulating one aspect of age-related metabolic dysfunction. In human white adipose tissue, periostin expression showed an unexpected positive correlation with age of study participants. This correlation, however, was no longer evident after adjusting for BMI or plasma lipid and liver function biomarkers. These findings taken together suggest that age-related alterations of the adipose tissue extracellular matrix may contribute to the development of metabolic disease by negatively affecting nutrient homeostasis.

Keywords: adipogenic progenitor cells; adipose tissue; aging; extracellular matrix; fatty acid metabolism; periostin.

Figure 1

The matricellular protein periostin is regulated by aging and metabolic challenges. (a, b) Heatmap of top 20 downregulated genes expressed in BAT‐ (a) and iWAT‐derived (b) APCs comparing old (65 weeks) to young (6 weeks) murine samples. (c) Periostin gene expression in BAT‐ and iWAT‐derived, FACS‐purified APCs of young (8 weeks, white bars) and old (65 weeks, gray bars) mice directly after isolation (left panel) and after in vitro cultivation (right panel; n = 3–6). (d) Western blot analysis of POSTN and β‐actin (ACTB) expression in iWAT (top panels), gWAT (middle panels), and BAT (lower panels) of young (8 weeks) compared to old (65 weeks) mice (n = 5). A protein marker lane is visible between the young and old tissue samples in the depiction of the BAT samples shown here. (e) Representative X‐Gal/H&E staining (400× magnification; Scale bar: 10 μm) in periostin‐driven LacZ reporter mouse strain in iWAT, gWAT, and BAT. (f) Postn mRNA in freshly isolated stromal‐vascular‐fraction (SVF, white bars) compared to isolated adipocytes (Adi, gray bars) purified from iWAT and gWAT of young C57BL/6 J mice (n = 8). (g) Postn mRNA in BAT, iWAT, and gWAT in young control mice (c; light gray bars), after 6 weeks of HFD (h; orange bars), after cold exposure (co; blue bars), or 180 min after injection of the β3‐adrenergic receptor agonist, CL316,243 (CL; dark gray bars; n = 7–9). (h, i) Western blot analysis of POSTN protein expression normalized to β‐actin (ACTB) in BAT, iWAT, and gWAT of male (h) and female (i) C57Bl/6 J wild‐type mice. Mean ± SEM; *p < 0.05, **p < 0.01, ***p < 0.001, assessed by unpaired t test or Mann–Whitney U test

Figure 2

Genetic deletion of Postn leads to mild growth retardation but does not affect AT development. (a) Postn gene expression in BAT, iWAT, and gWAT of male mice comparing wild‐type (WT, gray bars) and Postn‐KO animals (n = 3–4; n.d.—not detectable). (b) Protein expression of POSTN in different AT depots, for example, BAT, iWAT, gWAT, of male WT and Postn‐KO animals normalized to glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) expression. (c) Body weight of male and female mice comparing WT and Postn‐KO mice (n = 8–12). Gray bars represent WT controls, black bars represent Postn‐KO mice, applies to all subsequent panels. (d) Animal length of male and female WT and Postn‐KO animals (n = 4–5). (e) Tibia lengths of male and female WT and Postn‐KO animals (n = 4–7). (f, g) AT depot weights of male and female WT and Postn‐KO animals prior to normalization (f) or normalized to body weight (g; n = 3–6). Mean ± SEM; *p < 0.05, **p < 0.01, ***p < 0.001, assessed by unpaired t test

Figure 3

Mild impairment of cold‐induced thermogenesis in periostin‐deficient mice. (a) Rectal temperatures of male and female WT and Postn‐KO animals at room temperature (RT) and after 24 hr cold exposure (n = 5–12). Gray bars represent WT controls, black bars represent Postn‐KO mice, applies to all subsequent panels. (b) Body weight loss of male WT and Postn‐deleted mice after 72 hr of cold exposure (n = 10–11). (c) BAT, iWAT, and gWAT depot weights normalized to body weight of male WT and Postn‐KO mice after cold exposure for 72 hr (n = 10–11). (d) Body weight‐normalized tissue weights of extensor digitorum longus (EDL), tibialis anterior (TA), and quadriceps femoris (Quad) muscles and liver in male WT and Postn‐KO animals after cold exposure for 72 hr (n = 10–11). (e) Gene expression analysis of the brown/beige adipogenesis marker genes Cebpb, Prdm16, Ucp1, and Adrb3 in BAT, iWAT, and gWAT of male Postn‐deficient mice after cold exposure (n = 5–7). (f, g) Western blot analysis of UCP1 in BAT (f) and iWAT (g) of male WT and Postn‐KO animals after 72 hr cold exposure normalized to β‐actin (ACTB). (h) Gene expression analysis Cd36, Cpt1a, Cpt1b, and Scl2a4 (Glut4) in BAT, iWAT, and gWAT of male Postn‐deficient mice after cold exposure (n = 5–7). Data are shown as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 compared with WT animals assessed by unpaired t test or Mann–Whitney U test

Figure 4

Deletion of Postn leads to an impaired lipid metabolism after acute β‐adrenergic stimulation. (a, b) Gene expression of genes associated with brown adipogenesis, Ucp1, Pparg, Ppargc1a, Adrb3 (a) and lipid metabolism, Fasn, Ces1d, Atgl, and Hsl (b) in BAT, iWAT, and gWAT of male WT and Postn‐KO animals 180 min after i.p.‐injection of β3‐adrenergic receptor agonist, CL316,243. Gray bars indicate control mice, black bars indicate Postn‐KO mice, applies to all panels. (c, d) Western blot analysis and quantification of proteins associated with lipid metabolism, pHSL, HSL, ATGL, CD36, and PLIN1 in BAT, iWAT, and gWAT. Western blot signals were normalized to glyceraldehyde 3‐phosphate dehydrogenase (GAPDH). ^§pHSL and Plin1 antibodies were probed on the same membrane and normalized to GAPDH in the upper panel; ^#HSL, ATGL, and CD36 were probed on a separate membrane and normalized to GAPDH in the lower panel. Data are shown as mean ± SEM. n = 5. *p < 0.05, **p < 0.01 compared with WT animals assessed by Mann–Whitney U test

Figure 5

Postn deficiency impairs adipose tissue expansion during high‐fat diet feeding. (a) Body weight gain of male WT and Postn‐KO animals during 6 weeks of HFD feeding. Gray lines/circles/bars represent WT controls, black lines/triangles/bars represent Postn‐KO mice, applies to all subsequent panels. (b, c) NMR analysis of male WT and Postn‐KO animals assessing total fat mass (b) and lean mass (c). (d) Plasma levels of FFA, glycerol, TG, and glucose in male WT and Postn‐depleted animals after 6 weeks of HFD. (e) Plasma levels of insulin with and without high‐fat diet feeding in male WT and Postn‐depleted animals. (f) Representative images of H&E staining (200× magnification; scale bar: 20 μm, applies to all subsequent images of BAT) of BAT of male WT (upper panel) and male Postn‐KO mice (lower panel). (g) Quantitative analysis of lipid droplet size in BAT sections after H&E staining of male WT and knockout animals after 6 weeks of HFD as shown in previous panel. (h) Representative H&E staining (100× magnification; scale bar: 20 μm, applies to all subsequent images of WAT) of iWAT of male WT (upper panel) and male Postn‐KO mice (lower panel). (i) Quantitative analysis of adipocyte size analysis of male iWAT comparing WT to Postn‐KO animals after 6 weeks of HFD from images as shown in previous panel. (j) Representative H&E staining (100× magnification) of gWAT of male WT (upper panel) and male Postn‐KO mice (lower panel). (k) Adipocyte size analysis of male gWAT comparing WT to Postn‐KO animals after 6 weeks of HFD from images as shown in previous panel. Data are shown as mean ± SEM (n = 5–7). *p < 0.05, **p < 0.01, ***p < 0.001 as assessed by two‐way ANOVA with Bonferroni post hoc test (a–c, g, i, k) and unpaired t test (d, e)

Figure 6

Human periostin mRNA expression in different fat depots is negatively associated with obesity and parameters of glucose metabolism in humans. (a, b) Gene expression analysis of periostin mRNA in human sWAT (a) and human vWAT (b) biopsies collected from normal weight (body mass index (BMI) <25 kg/m²), overweight (BMI 25–29.9 kg/m²), and obese (BMI > 29.9 kg/m²) subjects. (c) Human periostin mRNA levels in sWAT (white bars) and vWAT (gray bars) of humans with normal glucose tolerance, impaired glucose tolerance and type 2 diabetes. Data are shown as mean ± SEM. n = 12–408. *p < 0.05, **p < 0.01, ***p < 0.001 assessed by one‐way (a, b) or two‐way (c) ANOVA with Bonferroni post hoc test. (d, e) Graphical depictions of Spearman partial correlation coefficients (ρ) and 95% confidence intervals (CI) of associations between participant age and human periostin mRNA expression in sWAT (panel d) and vWAT (panel e) following adjustment for body mass index (BMI), or lipid and liver function parameters (data shown in Table 1). *p < 0.05, **p < 0.01 indicate significant correlations