Specific visible radiation facilitates lipolysis in mature 3T3-L1 adipocytes via rhodopsin-dependent β3-adrenergic signaling

Effects of cortisol, epinephrine, and bisphenol contaminants on the transcriptional landscape of marine mammal blubber

Top ocean predators such as marine mammals are threatened by intensifying anthropogenic activity, and understanding the combined effects of multiple stressors on their physiology is critical for conservation efforts. We investigated potential interactions between stress hormones and bisphenol contaminants in a model marine mammal, the northern elephant seal (NES). We exposed precision-cut adipose tissue slices (PCATS) from blubber of weaned NES pups to cortisol (CORT), epinephrine (EPI), bisphenol A (BPA), bisphenol S (BPS), or their combinations (CORT-EPI, BPA-EPI, and BPS-EPI) ex vivo and identified hundreds of genes that were differentially regulated in response to these treatments. CORT altered expression of genes associated with lipolysis and adipogenesis, whereas EPI and CORT-EPI-regulated genes were associated with responses to hormones, lipid and protein turnover, immune function, and transcriptional and epigenetic regulation of gene expression, suggesting that EPI has wide-ranging and prolonged impacts on the transcriptional landscape and function of blubber. Bisphenol treatments alone had a weak impact on gene expression compared with stress hormones. However, the combination of EPI with bisphenols altered expression of genes associated with inflammation, cell stress, DNA damage, regulation of nuclear hormone receptor activity, cell cycle, mitochondrial function, primary ciliogenesis, and lipid metabolism in blubber. Our results suggest that CORT, EPI, bisphenols, and their combinations impact cellular, immune, and metabolic homeostasis in marine mammal blubber, which may affect the ability of marine mammals to sustain prolonged fasting during reproduction and migration, renew tissues, and mount appropriate responses to immune challenges and additional stressors.

Sunlight Exposure and Phototherapy: Perspectives for Healthy Aging in an Era of COVID-19

Most humans depend on sunlight exposure to satisfy their requirements for vitamin D₃. However, the destruction of the ozone layer in the past few decades has increased the risk of skin aging and wrinkling caused by excessive exposure to ultraviolet (UV) radiation, which may also promote the risk of skin cancer development. The promotion of public health recommendations to avoid sunlight exposure would reduce the risk of skin cancer, but it would also enhance the risk of vitamin D₃ insufficiency/deficiency, which may cause disease development and progression. In addition, the ongoing global COVID-19 pandemic may further reduce sunlight exposure due to stay-at-home policies, resulting in difficulty in active and healthy aging. In this review article, we performed a literature search in PubMed and provided an overview of basic and clinical data regarding the impact of sunlight exposure and vitamin D₃ on public health. We also discuss the potential mechanisms and clinical value of phototherapy with a full-spectrum light (notably blue, red, and near-infrared light) as an alternative to sunlight exposure, which may contribute to combating COVID-19 and promoting active and healthy aging in current aged/superaged societies.

Combination of Capsaicin and Capsiate Induces Browning in 3T3-L1 White Adipocytes via Activation of the Peroxisome Proliferator-Activated Receptor γ/β3-Adrenergic Receptor Signaling Pathways

This study investigated the effects and molecular mechanism of a combination of capsaicin and capsiate on promoting lipid metabolism and inducing browning in 3T3-L1 white adipocytes. The combination significantly suppressed lipid accumulation in adipocytes ( p = 0.019) and robustly improved lipid metabolic profiles, including decreased triacylglycerol (0.6703 ± 0.0385 versus 0.2849 ± 0.0188 mmol/g of protein; p < 0.001), total cholesterol (0.1282 ± 0.0241 versus 0.0651 ± 0.0178 mmol/g of protein; p = 0.003), and low-density lipoprotein cholesterol (0.0021 ± 0.0017 versus 0.0005 ± 0.0002 mmol/g of protein; p = 0.024) and increased high-density lipoprotein cholesterol (0.0162 ± 0.0141 versus 0.1002 ± 0.0167 mmol/g of protein; p = 0.012). Furthermore, this combination markedly upgraded the protein levels of cluster of differentiation 36 ( p = 0.007) and adipose triglyceride lipase ( p = 0.013) and phosphorylation of hormone-sensitive lipase at Ser660, Ser565, and Ser563 ( p < 0.001, p = 0.027, and p = 0.002, respectively), indicating increases of fatty acid transport and lipolysis. The levels of lipid metabolism regulators, phosphorylation of adenosine-monophosphate-activated protein kinases α and β ( p = 0.011, and p < 0.001, respectively), sirtuin 1 ( p = 0.004), and vanilloid transient receptor subtype I ( p = 0.014) were also increased by the combination. Moreover, the combination greatly activated the browning program in adipocytes, as demonstrated by increases in beige-specific gene and protein. Further research found that the protein levels of peroxisome proliferator-activated receptor γ (PPARγ; p = 0.001) and β₃-adrenergic receptor (β₃-AR; p = 0.026) were elevated by the combination, and most of the beige-specific markers were abolished by pretreatment of antagonists of PPARγ or β₃-AR. In conclusion, these results indicated that a combination of capsaicin and capsiate could induce browning in white adipocytes via activation of the PPARγ/β₃-AR signaling pathway, and this combination might be worth investigating as a potential cure for obesity.

The Role of Immature and Mature Adipocytes in Hair Cycling

Hair follicles (HFs) strongly interact with adipocytes within the dermal white adipose tissue (dWAT), suggesting a strong physiological dependence on the content of immature and mature adipocytes in this layer. This content is regulated by the proliferation and differentiation of adipocyte precursors, as well as by dedifferentiation of mature existing adipocytes. Spatially, long-range interactions between HFs and dWAT involve the exchange of extracellular vesicles which are differentially released by precursors, preadipocytes, and mature adipocytes. Different exogenous factors, including light irradiation, are likely to modify the release of adipocyte-derived exosomes in dWAT, which can lead to aberrations of the HF cycle. Consequently, dWAT should be considered as a potential target for the modulation of hair growth.

Improvement of high-glucose and insulin resistance of chromium malate in 3T3-L1 adipocytes by glucose uptake and insulin sensitivity signaling pathways and its mechanism

Previous study has revealed that chromium malate could improve insulin resistance and the regulation of fasting blood glucose in type 2 diabetic rats. This study was designed to investigate the effect of chromium malate on hypoglycemic and improve insulin resistance activities in 3T3-L1 adipocytes with insulin resistance and investigate the acting mechanism. The result indicated that chromium malate exhibited direct hypoglycemic activity in vitro. Compared with the model group, chromium malate could significantly promote the expression levels of GLUT-4, Akt, Irs-1, PPARγ, PI3K and p38-MAPK and their mRNA, increase p-AKT/AKT level, AKT and AMPKβ1 phosphorylation and reduce Irs-1 phosphorylation and p-Irs-1/Irs-1 level in 3T3-L1 adipocytes (p < 0.05). Chromium malate is more effective in regulating the proteins and mRNA expressions than those of chromium trichloride and chromium picolinate. Compared to the model group, pretreatment with the specific p38-MAPK inhibitor completely inhibited the GLUT-4 and Irs-1 proteins and mRNA expressions induced by the chromium malate. In conclusion, chromium malate had a beneficial influence on improvement of controlling glucose levels and insulin resistance in 3T3-L1 adipocytes with insulin resistance by regulating proteins productions and genes expressions in glucose uptake and insulin sensitivity signaling pathways.

Chromium malate could increase the related protein and mRNA levels in 3T3-L1 adipocytes with insulin resistant. Pretreatment with the inhibitor completely/partially inhibited the GLUT-4 and Irs-1 proteins and mRNA expression compared to model group.