A predominant role for parenchymal c-Jun amino terminal kinase (JNK) in the regulation of systemic insulin sensitivity - PubMed (original) (raw)

A predominant role for parenchymal c-Jun amino terminal kinase (JNK) in the regulation of systemic insulin sensitivity

Sara N Vallerie et al. PLoS One. 2008.

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Abstract

It has been established that c-Jun N-terminal kinase 1 (JNK1) is essential to the pathogenesis of insulin resistance and type 2 diabetes. Although JNK influences inflammatory signaling pathways, it remains unclear whether its activity in macrophages contributes to adipose tissue inflammation and ultimately to the regulation of systemic metabolism. To address whether the action of this critical inflammatory kinase in bone marrow-derived elements regulates inflammatory responses in obesity and is sufficient and necessary for the deterioration of insulin sensitivity, we performed bone marrow transplantation studies with wild type and JNK1-deficient mice. These studies illustrated that JNK1-deficiency in the bone marrow-derived elements (BMDE) was insufficient to impact macrophage infiltration or insulin sensitivity despite modest changes in the inflammatory profile of adipose tissue. Only when the parenchymal elements lacked JNK1 could we demonstrate a significant increase in systemic insulin sensitivity. These data indicate that while the JNK1 activity in BMDE is involved in metabolic regulation and adipose milieu, it is epistatic to JNK1 activity in the parenchymal tissue for regulation of metabolic homeostasis.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. Inflammatory responses in JNK1-deficient macrophages.

Primary macrophages isolated from wild type (WT) or JNK1-deficient (Jnk1−/−) mice were stimulated with 250 µM palmitate (PA) for 24 hours. Expression levels of IL-1β, IL-6 and TNF-α mRNAs were determined by real time quantitative RT-PCR and normalized to 18S rRNA. Data are normalized to bovine serum albumin (BSA) treated WT macrophages and expressed as mean ± s.e.m. Statistical significance is determined by Student's t test, * p<0.05 and *** p<0.005.

Figure 2

Figure 2. Effects of irradiation dosage on engraftment and body weight.

Mice that differ in CD45 cell surface markers were irradiated with 9, 10, and 12 Gy and transplanted with bone marrow (1×106 bone marrow cells) and the rate of chimerism in blood cells were determined by sorting with the specific antibodies for CD45.1 and CD45.2. In an additional control experiment, FACS analysis was performed without BMT using blood cells from C57BL/6J (CD45.2+) and B6.SJL PtprcaPep3b/BoyJ (CD45.1+) mice (A). FACS analysis using blood cells from CD45.1→CD45.2 BMT in mice that were irradiated with 9 Gy (B), 10 Gy (C), or 12 Gy (D). Body weight change in the three groups of mice (irradiated with 9, 10, and 12 Gy) following BMT on a regular diet (E). Percentage of reconstitution was calculated and displayed in each graph.

Figure 3

Figure 3. Generation of JNK1-deficient radiation chimeras using bone marrow transplantation.

The extent of engraftment of the transplanted cells in WT recipients after bone marrow transplantation was determined using genomic DNA isolated from whole blood and quantified with PCR-based allele distribution (A and B). Genomic DNA harvested from tail confirmed the presence of only the recipient genotype (A) while genomic DNA from liver, subcutaneous fat, and epididymal fat tissues (C) confirmed engraftment of donor (_Jnk1_-deficient) cells in WT recipients. Genomic DNA isolated from blood was quantified as in panel A except in the Jnk1−/− recipient groups (D and E). Genomic DNA isolated from the liver, subcutaneous fat, and epididymal fat tissues (F) of Jnk1−/− recipients confirmed the genotype and engraftment, respectively. At 8 weeks of age, all WT (G) and Jnk1−/− (H) recipient chimeras transplanted with WT or Jnk1−/− bone marrow cells were placed on high fat diet and body weights were monitored for the duration of experiments.

Figure 4

Figure 4. Steady state plasma lipid, glucose, insulin, and serum adipokine concentrations in JNK1-deficient chimeras.

Serum samples were collected after a 6 hr food withdrawal from mice from the indicated chimeric groups at 8 and 24 weeks of age. Triglycerides were measured from WT (A) and Jnk1−/− recipients (B) transplanted with either WT or Jnk1−/− bone marrow. Serum insulin (C) and blood glucose (D) levels were measured in the WT recipient groups. Serum insulin (E) and blood glucose (F) levels measured in the Jnk1−/− recipient groups. Serum resistin (G), leptin (H), and adiponectin (I) levels measured in the WT and Jnk1−/− recipient groups at 24 weeks of age. Data are expressed as mean ± s.e.m. Asterisk indicates statistical significance (p<0.05) in Student's t test.

Figure 5

Figure 5. Glucose tolerance and insulin sensitivity in JNK1-deficient chimeras.

Glucose (GTT) and insulin (ITT) tolerance tests were performed on mice at age 22 and 26 weeks, respectively. GTT (A) and ITT (B) experiments after intraperitoneal injection of glucose or insulin in WT recipient mice transplanted with WT or Jnk1−/− bone marrow. GTT (C) and ITT (D) in Jnk1−/− recipient mice transplanted with WT or Jnk1−/− bone marrow. All data are presented as mean ± s.e.m. Statistical analysis was performed by Student's t test. *p<0.05, **p<0.01, ***p<0.001.

Figure 6

Figure 6. Adipose tissue inflammation in JNK1-deficient chimeras.

Photomicrographs of adipose tissue sections were generated after staining with hematoxylin/eosin or anti-F4/80 and hematoxylin. Epididymal adipose tissue sections were prepared from all groups of mice, Jnk1−/−_→_WT, WT→WT, WT_→_Jnk1−/− and Jnk1−/−_→_Jnk1−/−, on high-fat diet for 27 weeks (A). In the same adipose tissue samples, total RNA was extracted and F4/80 mRNA expression level was quantified as an indicator of macrophage infiltration (B). Adipose tissue sections were also stained with anti-F4/80 antibody to detect the protein levels (C) and the number of crown like structures (CLS) were quantified (D). Expression levels of IL-1β, MCP-1, MIF-1, CD68, TNF-α, and IL-6 mRNAs in the epididymal adipose tissue were quantified to determine the cellular milieu in the WT (E) or Jnk1−/− (F) recipient groups transplanted with WT or Jnk1−/− bone marrow. Asterisk indicates statistical significance (p<0.05) in Student's t test.

Figure 7

Figure 7. Adipose tissue JNK activity in JNK1-deficient chimeras.

Total adipose tissue JNK kinase activity (A) and insulin-stimulated insulin receptor phosphorylation (B) were examined in JNK1-deficient mice transplanted with WT or Jnk1−/− bone marrow. Lower graph in panel B shows the quantification of insulin receptor phosphorylation normalized for insulin receptor protein levels. In the JNK kinase assay, the density of each lane is also shown numerically. Asterisk indicates statistical significance (p<0.05) in Student's t test.

Figure 8

Figure 8. Hepatic triglyceride accumulation and inflammatory cytokines expression in the liver and subcutaneous adipose tissue.

Photomicrographs of liver sections were generated after staining with hematoxylin/eosin. Liver sections were prepared from all groups of mice, Jnk1−/−_→_WT, WT→WT, WT_→_Jnk1−/− and Jnk1−/−_→_Jnk1−/−, on high-fat diet for 27 weeks (A). In the same liver samples, triglycerides were extracted and quantified (B). Additionally, total RNA was extracted and expression levels of IL-1β, IL-6, TNF-α, and F4/80 were quantified to determine the cellular milieu in the WT (C) or Jnk1−/− (D) recipient groups transplanted with WT or Jnk1−/− bone marrow. Similarly, mRNA was extracted from subcutaneous adipose tissue in the WT (E) or Jnk1−/− (F) recipient groups and subjected to quantitative-PCR analysis of the IL-1β, IL-6, TNF-α, and F4/80 expression. Asterisk indicates statistical significance (p<0.05) in Student's t test.

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References

    1. Hotamisligil GS, Shargill NS, Spiegelman BM. Adipose expression of tumor necrosis factor-alpha: direct role in obesity-linked insulin resistance. Science. 1993;259:87–91. - PubMed
    1. Uysal KT, Wiesbrock SM, Marino MW, Hotamisligil GS. Protection from obesity-induced insulin resistance in mice lacking TNF-alpha function. Nature. 1997;389:610–614. - PubMed
    1. Ventre J, Doebber T, Wu M, MacNaul K, Stevens K, et al. Targeted disruption of the tumor necrosis factor-alpha gene: metabolic consequences in obese and nonobese mice. Diabetes. 1997;46:1526–1531. - PubMed
    1. Rotter V, Nagaev I, Smith U. Interleukin-6 (IL-6) induces insulin resistance in 3T3-L1 adipocytes and is, like IL-8 and tumor necrosis factor-alpha, overexpressed in human fat cells from insulin-resistant subjects. J Biol Chem. 2003;278:45777–45784. - PubMed
    1. Sartipy P, Loskutoff DJ. Monocyte chemoattractant protein 1 in obesity and insulin resistance. Proc Natl Acad Sci U S A. 2003;100:7265–7270. - PMC - PubMed

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