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miR ‐ 34a − / − mice are susceptible to diet ‐ induced obesity

View Article: PubMed Central - PubMed

ABSTRACT

Objective: MicroRNA (miR)−34a regulates inflammatory pathways, and increased transcripts have been observed in serum and subcutaneous adipose of subjects who have obesity and type 2 diabetes. Therefore, the role of miR‐34a in adipose tissue inflammation and lipid metabolism in murine diet‐induced obesity was investigated.

Methods: Wild‐type (WT) and miR‐34a−/− mice were fed chow or high‐fat diet (HFD) for 24 weeks. WT and miR‐34a−/− bone marrow‐derived macrophages were cultured in vitro with macrophage colony‐stimulating factor (M‐CSF). Brown and white preadipocytes were cultured from the stromal vascular fraction (SVF) of intrascapular brown and epididymal white adipose tissue (eWAT), with rosiglitazone.

Results: HFD‐fed miR‐34a−/− mice were significantly heavier with a greater increase in eWAT weight than WT. miR‐34a−/− eWAT had a smaller adipocyte area, which significantly increased with HFD. miR‐34a−/− eWAT showed basal increases in Cd36, Hmgcr, Lxrα, Pgc1α, and Fasn. miR‐34a−/− intrascapular brown adipose tissue had basal reductions in c/ebpα and c/ebpβ, with in vitro miR‐34a−/− white adipocytes showing increased lipid content. An F4/80high macrophage population was present in HFD miR‐34a−/− eWAT, with increased IL‐10 transcripts and serum IL‐5 protein. Finally, miR‐34a−/− bone marrow‐derived macrophages showed an ablated CXCL1 response to tumor necrosis factor‐α.

Conclusions: These findings suggest a multifactorial role of miR‐34a in controlling susceptibility to obesity, by regulating inflammatory and metabolic pathways.

No MeSH data available.


Related in: MedlinePlus

Expression of miR‐34a in adipose tissue. (A) In situ hybridization (ISH) images of miR‐34a expression (purple) compared with a Scramble (Scr; red) negative control in epididymal (e)WAT from WT mice fed chow or high‐fat diet (HFD) for 24 weeks and omental adipose from patients with obesity undergoing bariatric surgery. RT‐qPCR data showing expression of miR‐34a and 34a* in (B) eWAT and (C) liver and intrascapular (i)BAT collected from WT mice 24 weeks after commencing a chow vs. HFD. (D) RT‐qPCR quantification of miR‐34a and 34a* transcripts in WT in vitro bone marrow‐derived macrophages (BMDM) ± 45.45 ng/mL tumor necrosis factor (TNF)‐α for 24 h. Data represented as relative quantification (RQ) with RQmin − RQmax values, normalized to RNU6; n = 3–4 for eWAT, n = 5–6 for liver, n = 6 for iBAT, and n = 3 for BMDMs. *P < 0.05, **P < 0.01, unpaired Student's t‐test.
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oby21561-fig-0001: Expression of miR‐34a in adipose tissue. (A) In situ hybridization (ISH) images of miR‐34a expression (purple) compared with a Scramble (Scr; red) negative control in epididymal (e)WAT from WT mice fed chow or high‐fat diet (HFD) for 24 weeks and omental adipose from patients with obesity undergoing bariatric surgery. RT‐qPCR data showing expression of miR‐34a and 34a* in (B) eWAT and (C) liver and intrascapular (i)BAT collected from WT mice 24 weeks after commencing a chow vs. HFD. (D) RT‐qPCR quantification of miR‐34a and 34a* transcripts in WT in vitro bone marrow‐derived macrophages (BMDM) ± 45.45 ng/mL tumor necrosis factor (TNF)‐α for 24 h. Data represented as relative quantification (RQ) with RQmin − RQmax values, normalized to RNU6; n = 3–4 for eWAT, n = 5–6 for liver, n = 6 for iBAT, and n = 3 for BMDMs. *P < 0.05, **P < 0.01, unpaired Student's t‐test.

Mentions: In situ hybridization showed miR‐34a distribution within visceral WAT was ubiquitous throughout the epididymal (e)WAT of WT mice on chow and HFD and omental adipose from bariatric surgery patients with obesity (Figure 1A). Similarly, no change was observed in miR‐34a or miR‐34a* transcripts between WT chow and HFD groups (Figure 1B). However, we observed increases in both miR‐34a and 34a* transcripts within the liver (P = 0.0088, P = 0.0247) and intrascapular (i)BAT (P = 0.0433, P = 0.0399) during HFD feeding (Figure 1C). Furthermore, we observed an increase in miR‐34a (P = 0.0086) and miR‐34a* (P = 0.0461) transcripts in WT bone marrow‐derived macrophages (BMDMs) when stimulated with TNF‐α (Figure 1D). We examined the other miR‐34 family members but found no expression changes (Supporting Information Figure S1).


miR ‐ 34a − / − mice are susceptible to diet ‐ induced obesity
Expression of miR‐34a in adipose tissue. (A) In situ hybridization (ISH) images of miR‐34a expression (purple) compared with a Scramble (Scr; red) negative control in epididymal (e)WAT from WT mice fed chow or high‐fat diet (HFD) for 24 weeks and omental adipose from patients with obesity undergoing bariatric surgery. RT‐qPCR data showing expression of miR‐34a and 34a* in (B) eWAT and (C) liver and intrascapular (i)BAT collected from WT mice 24 weeks after commencing a chow vs. HFD. (D) RT‐qPCR quantification of miR‐34a and 34a* transcripts in WT in vitro bone marrow‐derived macrophages (BMDM) ± 45.45 ng/mL tumor necrosis factor (TNF)‐α for 24 h. Data represented as relative quantification (RQ) with RQmin − RQmax values, normalized to RNU6; n = 3–4 for eWAT, n = 5–6 for liver, n = 6 for iBAT, and n = 3 for BMDMs. *P < 0.05, **P < 0.01, unpaired Student's t‐test.
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oby21561-fig-0001: Expression of miR‐34a in adipose tissue. (A) In situ hybridization (ISH) images of miR‐34a expression (purple) compared with a Scramble (Scr; red) negative control in epididymal (e)WAT from WT mice fed chow or high‐fat diet (HFD) for 24 weeks and omental adipose from patients with obesity undergoing bariatric surgery. RT‐qPCR data showing expression of miR‐34a and 34a* in (B) eWAT and (C) liver and intrascapular (i)BAT collected from WT mice 24 weeks after commencing a chow vs. HFD. (D) RT‐qPCR quantification of miR‐34a and 34a* transcripts in WT in vitro bone marrow‐derived macrophages (BMDM) ± 45.45 ng/mL tumor necrosis factor (TNF)‐α for 24 h. Data represented as relative quantification (RQ) with RQmin − RQmax values, normalized to RNU6; n = 3–4 for eWAT, n = 5–6 for liver, n = 6 for iBAT, and n = 3 for BMDMs. *P < 0.05, **P < 0.01, unpaired Student's t‐test.
Mentions: In situ hybridization showed miR‐34a distribution within visceral WAT was ubiquitous throughout the epididymal (e)WAT of WT mice on chow and HFD and omental adipose from bariatric surgery patients with obesity (Figure 1A). Similarly, no change was observed in miR‐34a or miR‐34a* transcripts between WT chow and HFD groups (Figure 1B). However, we observed increases in both miR‐34a and 34a* transcripts within the liver (P = 0.0088, P = 0.0247) and intrascapular (i)BAT (P = 0.0433, P = 0.0399) during HFD feeding (Figure 1C). Furthermore, we observed an increase in miR‐34a (P = 0.0086) and miR‐34a* (P = 0.0461) transcripts in WT bone marrow‐derived macrophages (BMDMs) when stimulated with TNF‐α (Figure 1D). We examined the other miR‐34 family members but found no expression changes (Supporting Information Figure S1).

View Article: PubMed Central - PubMed

ABSTRACT

Objective: MicroRNA (miR)&minus;34a regulates inflammatory pathways, and increased transcripts have been observed in serum and subcutaneous adipose of subjects who have obesity and type 2 diabetes. Therefore, the role of miR&#8208;34a in adipose tissue inflammation and lipid metabolism in murine diet&#8208;induced obesity was investigated.

Methods: Wild&#8208;type (WT) and miR&#8208;34a&minus;/&minus; mice were fed chow or high&#8208;fat diet (HFD) for 24 weeks. WT and miR&#8208;34a&minus;/&minus; bone marrow&#8208;derived macrophages were cultured in vitro with macrophage colony&#8208;stimulating factor (M&#8208;CSF). Brown and white preadipocytes were cultured from the stromal vascular fraction (SVF) of intrascapular brown and epididymal white adipose tissue (eWAT), with rosiglitazone.

Results: HFD&#8208;fed miR&#8208;34a&minus;/&minus; mice were significantly heavier with a greater increase in eWAT weight than WT. miR&#8208;34a&minus;/&minus; eWAT had a smaller adipocyte area, which significantly increased with HFD. miR&#8208;34a&minus;/&minus; eWAT showed basal increases in Cd36, Hmgcr, Lxr&alpha;, Pgc1&alpha;, and Fasn. miR&#8208;34a&minus;/&minus; intrascapular brown adipose tissue had basal reductions in c/ebp&alpha; and c/ebp&beta;, with in vitro miR&#8208;34a&minus;/&minus; white adipocytes showing increased lipid content. An F4/80high macrophage population was present in HFD miR&#8208;34a&minus;/&minus; eWAT, with increased IL&#8208;10 transcripts and serum IL&#8208;5 protein. Finally, miR&#8208;34a&minus;/&minus; bone marrow&#8208;derived macrophages showed an ablated CXCL1 response to tumor necrosis factor&#8208;&alpha;.

Conclusions: These findings suggest a multifactorial role of miR&#8208;34a in controlling susceptibility to obesity, by regulating inflammatory and metabolic pathways.

No MeSH data available.


Related in: MedlinePlus