Research ArticleMetabolism

Mitophagy controls beige adipocyte maintenance through a Parkin-dependent and UCP1-independent mechanism

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Science Signaling  24 Apr 2018:
Vol. 11, Issue 527, eaap8526
DOI: 10.1126/scisignal.aap8526
  • Fig. 1 Regulation of mitophagy during the beige-to-white adipocyte transition.

    (A) Mitophagic activity in adipose tissues was monitored in vivo by using mitochondrial-targeted Keima (mt-Keima) mice. (B) Schematic illustration of the experiments. mt-Keima mice were treated with the β3-adrenergic receptor (β3-AR) agonist CL316,243 or vehicle (saline) for seven consecutive days and harvested at days 0, 15, and 30 after β3-AR agonist withdrawal. Mitophagic activity in the adipose tissue from each mouse was measured by flow cytometry. (C) Mature adipocytes were isolated from the interscapular brown adipose tissue (iBAT; brown) or the inguinal white adipose tissue (IngWAT; beige) of mt-Keima mice. Signals from green (458 nm) and red (561 nm) channels were detected by flow cytometry. ***P < 0.001 by unpaired Student’s t test. n = 8 mice per group. The inset graph shows medians with interquartile range. (D) Mitophagic activity in the IngWAT of mt-Keima mice in (B) based on the ratio of red/green fluorescence intensity. Y axis represents the number of adipocytes normalized to mode. Data are representative of four independent experiments. (E) Quantification of flow cytometry data in (D) by analyzing the median of red/green fluorescence intensity ratio. *P < 0.05 and ***P < 0.001 by one-way analysis of variance (ANOVA) with post hoc test by Tukey’s method. n.s., not significant. Data are mean ± SEM, relative to vehicle-treated mt-Keima mice. (F) Mitophagic activity in the iBAT of mt-Keima mice in (B). Data are representative of four independent experiments. (G) Quantification of flow cytometry data in (F) by analyzing the median of red/green fluorescence intensity ratio. Data are as mean ± SEM, relative to vehicle-treated mt-Keima mice.

  • Fig. 2 Parkin is required for beige adipocyte maintenance in vivo.

    (A) Schematic illustration of the experiments. Park2 KO mice and control mice were treated with the β3-AR agonist CL316,243 or vehicle (saline) for seven consecutive days. Adipose tissue samples were harvested at days 0 and 15 after β3-AR agonist withdrawal. (B) Park2 mRNA expression in the IngWAT of control and Park2 KO mice. n.d., not detected. n = 5 mice per group. (C) Tissue weight of the IngWAT of control and Park2 KO mice at days 0 and 15 after β3-AR agonist withdrawal. ***P < 0.001 by two-way ANOVA with post hoc test by Tukey’s method. n = 6 to 8 mice per group. Data are mean ± SEM. (D) Tissue weight of the iBAT in (C). (E) Tissue weight of the epididymal WAT (EpiWAT) in (C). (F) Representative immunoblotting for uncoupling protein 1 (UCP1) and mitochondrial complexes (as indicated) in the IngWAT of control and Park2 KO mice treated with CL316,243 at days 0 and 15. β-Actin was used as a loading control. Protein molecular weight (kDa) is shown on the right. Data are representative of three independent experiments. (G) Immunohistochemistry of UCP1 in the inguinal WAT of mice in (F). Vehicle (saline)–treated mice were shown as a reference. Scale bar, 100 μm. n = 3 mice per group. (H) Relative mRNA expression of thermogenic genes (as indicated) in the IngWAT of control and Park2 KO mice at day 15 after β3-AR agonist withdrawal. *P < 0.05 and **P < 0.01 by unpaired Student’s t test. n = 8 mice per group. Data are mean ± SEM. (I) OCR in the IngWAT of control and Park2 KO mice at day 0. OCR data were shown per 1 mg of tissue. Tissues were treated with isoproterenol (ISO) or vehicle (basal). *P < 0.05 and **P < 0.01 by two-way ANOVA with post hoc test by paired or unpaired Student’s t test. n = 6 mice per group. Data are mean ± SEM. (J) OCR in the IngWAT of control and Park2 KO mice at day 15 after β3-AR agonist withdrawal. *P < 0.05, **P < 0.01, and ***P < 0.001 by two-way ANOVA with post hoc test by paired or unpaired Student’s t test. n = 6 mice per group. Data are mean ± SEM. (K) Representative immunoblotting for UCP1 and mitochondrial complexes (as indicated) in the iBAT of control and Park2 KO mice treated with CL316,243 at days 0 and 15. β-Actin was used as a loading control. The molecular weight is shown on the right. Data are representative of three independent experiments. (L) Immunohistochemistry of UCP1 in the iBAT of mice in (K). Vehicle (saline)–treated mice were shown as a reference. Scale bar, 100 μm. n = 3 mice per group. (M) Relative mRNA expression of thermogenic genes (as indicated) in the iBAT of control and Park2 KO mice at day 15 after β3-AR agonist withdrawal. n = 8 mice per group. Data are mean ± SEM. (N) OCR in the iBAT of control and Park2 KO mice at day 0. OCR data were shown per 1 mg of tissue. Tissues were treated with isoproterenol or vehicle (basal). *P < 0.05 by two-way ANOVA with post hoc test by paired or unpaired Student’s t test. n = 6 mice per group. Data are mean ± SEM. (O) OCR in the iBAT of control and Park2 KO mice at day 15 after β3-AR agonist withdrawal. *P < 0.05 by two-way ANOVA with post hoc test by paired or unpaired Student’s t test. n = 6 mice per group. Data are mean ± SEM. WT, wild type.

  • Fig. 3 UCP1 is dispensable for beige adipocyte maintenance in vivo.

    (A) Schematic illustration of the experiments. Ucp1 KO mice and control mice were treated with the β3-AR agonist CL316,243 or vehicle (saline) for seven consecutive days. Adipose tissue samples were harvested at days 0 and 15 after β3-AR agonist withdrawal under thermoneutrality (30°C). (B) Tissue weight of the IngWAT of control and Ucp1 KO mice at days 0 and 15 after β3-AR agonist withdrawal. *P < 0.05, **P < 0.01, and ***P < 0.001 by two-way ANOVA with post hoc test by Tukey’s method. n = 6 to 8 mice per group. Data are mean ± SEM. (C) Tissue weight of the iBAT in (B). (D) Tissue weight of the epididymal WAT in (B). (E) Representative immunoblotting for UCP1 and mitochondrial complexes (as indicated) in the IngWAT of control and Ucp1 KO mice treated with CL316,243 at days 0 and 15. β-Actin was used as a loading control. The molecular weight is shown on the right. Data are representative of three independent experiments. (F) Hematoxylin and eosin staining in the IngWAT of mice in (E). Vehicle (saline)–treated mice were shown as a reference. Scale bar, 100 μm. n = 3 mice per group. (G) Relative mRNA expression of thermogenic genes (as indicated) in the IngWAT of control and Ucp1 KO mice at day 15 after β3-AR agonist withdrawal. **P < 0.01 by unpaired Student’s t test. n = 3 mice per group. Data are mean ± SEM. (H) OCR in the IngWAT of control and Ucp1 KO mice at day 0 after β3-AR agonist withdrawal. OCR data were shown per 1 mg of tissue. Tissues were treated with isoproterenol or vehicle (basal). *P < 0.05 by two-way ANOVA with post hoc test by paired or unpaired t test. n = 6 mice per group. Data are mean ± SEM. (I) OCR in the IngWAT of control and Ucp1 KO mice at day 15 after β3-AR agonist withdrawal. *P < 0.05 by two-way ANOVA with post hoc test by paired or unpaired t test. n = 6. Data are mean ± SEM.

  • Fig. 4 Norepinephrine inhibits Parkin protein recruitment to depolarized mitochondria in beige adipocytes through the PKA pathway.

    (A) Yellow fluorescent protein (YFP)–Parkin was expressed in beige adipocytes derived from wild-type mice. Differentiated adipocytes were pretreated with a PKA [cAMP (cyclic adenosine monophosphate)–dependent protein kinase] inhibitor (PKI) or vehicle for 1 hour. Cells were treated with norepinephrine (NE) for 30 min and CCCP (carbonyl cyanide m-chlorophenylhydrazine) for 3 hours. Mitochondria were stained for Tom20 (red), and nuclei were stained with 4′,6-diamidino-2-phenylindole (DAPI) (blue). YFP-Parkin localization to the mitochondria was analyzed by confocal microscopy. Arrowheads indicate punctae of YFP-Parkin recruited to the mitochondria. Scale bars, 20 μm. (B) Quantification of Parkin localization in the mitochondria in (A). ***P < 0.001 by one-way ANOVA with post hoc test by Tukey’s method. A total of 405 cells from 10 independent images were analyzed for each experimental group. Data are mean ± SEM. The study was repeated in three independent experiments. (C) Phosphorylated (P) Parkin protein was detected by immunoprecipitation (IP) of phospho-PKA substrates followed by immunoblotting (IB) using a Parkin antibody. Wild-type inguinal cells were pretreated with vehicle or PKI and then with norepinephrine at 1 or 3 μM for 30 min. Immunoblotting of total Parkin and β-actin is shown (Input). The study was repeated in three independent experiments. IgG, immunoglobulin G. (D) YFP-Parkin was expressed in UCP1-null beige adipocytes derived from Ucp1 KO mice. The experiments were performed according to (A). Scale bars, 20 μm. (E) Quantification of Parkin mitochondrial localization in Ucp1 KO beige adipocytes in (D). ***P < 0.001 by one-way ANOVA with post hoc test by Tukey’s method. A total of 360 cells from 10 independent images were analyzed for each experimental group. Data are mean ± SEM.

Supplementary Materials

  • www.sciencesignaling.org/cgi/content/full/11/527/eaap8526/DC1

    Fig. S1. Validation of mitophagy monitoring in mt-Keima mice.

    Fig. S2. Genetic requirement of Parkin for beige adipocyte maintenance in vivo.

    Fig. S3. Analyses of the iBAT of Ucp1 KO mice after β3-AR agonist withdrawal.

    Fig. S4. Regulation of Parkin recruitment to the mitochondria by the PKA signaling pathway.

    Table S1. Oligonucleotide sequences of quantitative RT-PCR primers.

  • Supplementary Materials for:

    Mitophagy controls beige adipocyte maintenance through a Parkin-dependent and UCP1-independent mechanism

    Xiaodan Lu, Svetlana Altshuler-Keylin, Qiang Wang, Yong Chen, Carlos Henrique Sponton, Kenji Ikeda, Pema Maretich, Takeshi Yoneshiro, Shingo Kajimura*

    *Corresponding author. Email: shingo.kajimura{at}ucsf.edu

    This PDF file includes:

    • Fig. S1. Validation of mitophagy monitoring in mt-Keima mice.
    • Fig. S2. Genetic requirement of Parkin for beige adipocyte maintenance in vivo.
    • Fig. S3. Analyses of the iBAT of Ucp1 KO mice after β3-AR agonist withdrawal.
    • Fig. S4. Regulation of Parkin recruitment to the mitochondria by the PKA signaling pathway.
    • Table S1. Oligonucleotide sequences of quantitative RT-PCR primers.

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    © 2018 American Association for the Advancement of Science

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