RKIP phosphorylation–dependent ERK1 activation stimulates adipogenic lipid accumulation in 3T3-L1 preadipocytes overexpressing LC3

Journal Article · Fri Sep 09 04:00:00 EDT 2016 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2016.07.107· OSTI ID:22606202

Hahm, Jong Ryeal ^[1]; Ahmed, Mahmoud ^[2]

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1. Department of Internal Medicine, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of)
2. Department of Biochemistry and Convergence Medical Science, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of)

3T3-L1 preadipocytes undergo adipogenesis in response to treatment with dexamethaxone, 1-methyl-3-isobutylxanthine, and insulin (DMI) through activation of several adipogenic transcription factors. Many autophagy-related proteins are also highly activated in the earlier stages of adipogenesis, and the LC3 conjugation system is required for formation of lipid droplets. Here, we investigated the effect of overexpression of green fluorescent protein (GFP)-LC3 fusion protein on adipogenesis. Overexpression of GFP-LC3 in 3T3-L1 preadipocytes using poly-L-lysine-assisted adenoviral GFP-LC3 transduction was sufficient to produce intracellular lipid droplets. Indeed, GFP-LC3 overexpression stimulated expression of some adipogenic transcription factors (e.g., C/EBPα or β, PPARγ, SREBP2). In particular, SREBP2 was highly activated in preadipocytes transfected with adenoviral GFP-LC3. Also, phosphorylation of Raf kinase inhibitory protein (RKIP) at serine 153, consequently stimulating extracellular-signal regulated kinase (ERK)1 activity, was significantly increased during adipogenesis induced by either poly-L-lysine-assisted adenoviral GFP-LC3 transduction or culture in the presence of dexamethasone, 1-methyl-3-isobutylxanthine, and insulin. Furthermore, RKIP knockdown promoted ERK1 and PPARγ activation, and significantly increased the intracellular accumulation of triacylglycerides in DMI-induced adipogenesis. In conclusion, GFP-LC3 overexpression in 3T3-L1 preadipocytes stimulates adipocyte differentiation via direct modulation of RKIP-dependent ERK1 activity. - Highlights: • Overexpression of GFP-LC3 in 3T3-L1 cells produces intracellular lipid droplets. • SREBP2 is highly activated in preadipocytes transfected with adenoviral GFP-LC3. • RKIP phosphorylation at serine 153 is significantly increased during adipogenesis. • RKIP knockdown promotes ERK1 and PPARγ activation during adipogenesis. • RKIP-dependent ERK1 activation increases triacylglycerides in adipocytes.

• OSTI ID: 22606202
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 1 Vol. 478; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
DEXAMETHASONE
FLUORESCENCE
INSULIN
LIPIDS
LYSINE
PHOSPHORYLATION
SERINE
TRANSCRIPTION
TRANSCRIPTION FACTORS