33 research outputs found

    3T3-L1 Preadipocytes Exhibit Heightened Monocyte-Chemoattractant Protein-1 Response to Acute Fatty Acid Exposure

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    <div><p>Preadipocytes contribute to the inflammatory responses within adipose tissue. Whilst fatty acids are known to elicit an inflammatory response within adipose tissue, the relative contribution of preadipocytes and mature adipocytes to this is yet to be determined. We aimed to examine the actions of common dietary fatty acids on the acute inflammatory and adipokine response in 3T3-L1 preadipocytes and differentiated mature adipocytes. Gene expression levels of key adipokines in 3T3-L1 preadipocytes and adipocytes were determined following incubation with palmitic acid, myristic acid or oleic acid and positive inflammatory control, lipopolysaccharide for 2 and 4 h. Inflammatory kinase signalling was assessed by analysis of nuclear factor-κB, p38-mitogen-activated protein kinase and c-jun amino-terminal kinase phosphorylation. Under basal conditions, intracellular monocyte chemoattractant protein-1 and interleukin-6 gene expression levels were increased in preadipocytes, whereas mature adipocytes expressed increased gene expression levels of leptin and adiponectin. Fatty acid exposure at 2 and 4 h increased both monocyte chemoattractant protein-1 and interleukin-6 gene expression levels in preadipocytes to greater levels than in mature adipocytes. There was an accompanying increase of inhibitor of κB-α degradation and nuclear factor-κB (p65) (Ser536) phosphorylation with fatty acid exposure in the preadipocytes only. The current study points to preadipocytes rather than the adipocytes as the contributors to both immune cell recruitment and inflammatory adipokine secretion with acute increases in fatty acids.</p></div

    Representative immunoblots of MAPK phosphorylation in 3T3-L1 preadipocytes and mature adipocytes.

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    <p>3T3-L1 cells were treated with LPS (10 ng/ml); Palmitic acid (0.5 mM); Myristic acid (0.5 mM); and Oleic acid (0.5 mM) for 0, 1 and 2 h. Phosphorylation levels of p38 (Thr180/Tyr182) relative to total p38; and phosphor-JNK (Thr183/Tyr185) relative to total JNK were measured by Western blot analysis in 3T3-L1 (A) preadipocytes and (B) mature adipocytes (n = 5).</p

    TNFα mRNA levels in 3T3-L1 preadipocytes and adipocytes.

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    <p>TNFα mRNA expression of 3T3-L1 preadipocytes (hatched bars) and adipocytes (open bars) treated with (A) LPS (10 ng/ml); (B) Palmitic acid (0.5 mM); (C) Myristic acid (0.5 mM); and (D) Oleic acid (0.5 mM) at 0, 2 and 4 h. Data are presented as mean ±SEM (<i>n</i> = 5) normalised to 36B4. *** p&lt;0.001 versus preadipocytes, <sup>##</sup> p&lt;0.01 versus 0 h. Main cell type effect C p&lt;0.05, CC p&lt;0.01.</p

    IL-6 mRNA levels in 3T3-L1 preadipocytes and adipocytes.

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    <p>IL-6 gene expression levels of 3T3-L1 preadipocytes (hatched bars) and adipocytes (open bars) treated with (A) LPS (10 ng/ml); (B) Palmitic acid (0.5 mM); (C) Myristic acid (0.5 mM); and (D) Oleic acid (0.5 mM) at 0, 2 and 4 h. Data are presented as mean ±SEM (<i>n</i> = 5) normalised to 36B4. *** p&lt;0.001 versus preadipocytes, <sup>#</sup> p&lt;0.05, <sup>##</sup> p&lt;0.01, <sup>###</sup> p&lt;0.001 versus 0 h. Main time effect T p&lt;0.05.</p

    MCP-1 mRNA levels in 3T3-L1 preadipocytes and adipocytes.

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    <p>MCP-1 gene expression levels of 3T3-L1 preadipocytes (hatched bars) and adipocytes (open bars) treated with (A) LPS (10 ng/ml); (B) Palmitic acid (0.51 mM); (C) Myristic acid (0.5 mM); and (D) Oleic acid (0.5 mM) at 0, 2 and 4 h. Data are presented as mean ±SEM (<i>n</i> = 5) normalised to 36B4. ** p&lt;0.01, *** p&lt;0.001 versus preadipocytes, <sup>##</sup> p&lt;0.01, <sup>###</sup> p&lt;0.001 versus 0 h. Main time effect T p&lt;0.05, main cell type effect CC p&lt;0.01.</p

    Acute resistance exercise modulates microRNA expression profiles: Combined tissue and circulatory targeted analyses

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    <div><p>A subset of short non-coding RNAs, microRNAs (miRs), have been identified in the regulation of skeletal muscle hypertrophy and atrophy. Expressed within cells, miRs are also present in circulation (c-miR) and have a putative role in cross-tissue signalling. The aim of this study was to examine the impact of a single bout of high intensity resistance exercise (RE) on skeletal muscle and circulatory miRs harvested simultaneously. Resistance trained males (n = 9, 24.6 ± 4.9 years) undertook a single bout of high volume RE with venous blood and muscle biopsies collected before, 2 and 4hr post-exercise. Real time polymerase chain reaction (Rt-PCR) analyses was performed on 30 miRs that have previously been shown to be required for skeletal muscle function. Of these, 6 miRs were significantly altered within muscle following exercise; miR-23a, -133a, -146a, -206, -378b and 486. Analysis of these same miRs in circulation demonstrated minimal alterations with exercise, although c-miR-133a (~4 fold, p = 0.049) and c-miR-149 (~2.4 fold; p = 0.006) were increased 4hr post-exercise. Thus a single bout of RE results in the increased abundance of a subset of miRs within the skeletal muscle, which was not evident in plasma. The lack a qualitative agreement in the response pattern of intramuscular and circulating miR expression suggests the analysis of circulatory miRs is not reflective of the miR responses within skeletal muscle after exercise.</p></div

    c-miR fold change to pre exercise.

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    <p>(<b>A</b>) c-miR-133a and (<b>B</b>) c-miR-149 expression normalized to geomean of 5 endogenous stable miRs (Significant changes from baseline represented as * p≤0.05, ** p<0.01 and *** p<0.001, trends from baseline 0.05</p

    Mean (± SE) values of the incremental test to exhaustion of Normoxic (N; n = 8) and Hypoxic (H; n = 10) groups.

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    <p>W0: pre-; W4: post-training; VO<sub>2max</sub>: highest value of the oxygen consumption averaged over 30 s; PPO: peak power output; VE<sub>max</sub>: highest value of ventilation averaged over 30 s; RPE: rate of perceived exertion.</p><p>*P&lt;0.05 for the differences within a group versus W0; <sup>§</sup>P&lt;0.05 for the differences between groups at a matched time point.</p
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