Ocimum basilicum L. Methanol Extract Enhances Mitochondrial Efficiency and Decreases Adipokine Levels in Maturing Adipocytes Which Regulate Macrophage Systemic Inflammation.

Excessive storage of lipids in visceral or ectopic sites stimulates adipokine production, which attracts macrophages. This process determines the pro- and anti-inflammatory response regulation in adipose tissue during obesity-associated systemic inflammation. The present study aimed to identify the composition of Ocimum basilicum L. (basil) seed extract and to determine its bio-efficacy on adipocyte thermogenesis or fatty acid oxidation and inhibition of lipid accumulation and adipokine secretion. Ocimum basilicum L. seed methanol extract (BSME) was utilized to analyze the cytotoxicity vs. control; lipid accumulation assay (oil red O and Nile red staining), adipogenesis and mitochondrial-thermogenesis-related gene expression vs. vehicle control were analyzed by PCR assay. In addition, vehicle control and BSME-treated adipocytes condition media were collected and treated with lipopolysaccharide (LPS)-induced macrophage to identify the macrophage polarization. The results shown that the active components present in BSME did not produce significant cytotoxicity in preadipocytes or macrophages in the MTT assay. Furthermore, oil red O and Nile red staining assay confirmed that 80 and 160 µg/dL concentrations of BSME effectively arrested lipid accumulation and inhibited adipocyte maturation, when compared with tea polyphenols. Gene expression level of adipocyte hyperplasia (CEBPα, PPARγ) and lipogenesis (LPL)-related genes have been significantly (p ≤ 0.05) downregulated, and mitochondrial-thermogenesis-associated genes (PPARγc1α, UCP-1, prdm16) have been significantly (p ≤ 0.001) upregulated. The BSME-treated, maturing, adipocyte-secreted proteins were detected with a decreased protein level of leptin, TNF-α, IL-6 and STAT-6, which are associated with insulin resistance and macrophage recruitment. The "LPS-stimulated macrophage" treated with "BSME-treated adipocytes condition media", shown with significant (p ≤ 0.001) decrease in metabolic-inflammation-related proteins-such as PGE-2, MCP-1, TNF-α and NF-κB-were majorly associated with the development of foam cell formation and progression of atherosclerotic lesion. The present findings concluded that the availability of active principles in basil seed effectively inhibit adipocyte hypertrophy, macrophage polarization, and the inflammation associated with insulin resistance and thrombosis development. Ocimum basilicum L. seed may be useful as a dietary supplement to enhance fatty acid oxidation, which aids in overcoming metabolic complications.

HDAC6 regulates thermogenesis of brown adipocytes through activating PKA to induce UCP1 expression.

Mitochondrial uncoupling protein 1 (UCP1) is responsible for nonshivering thermogenesis in brown adipose tissue (BAT). UCP1 increases the conductance of the inner mitochondrial membrane (IMM) for protons to make BAT mitochondria generate heat rather than ATP. HDAC6 is a cytosolic deacetylase for non-histone substrates to regulate various cellular processes, including mitochondrial quality control and dynamics. Here, we showed that the body temperature of HDAC6 knockout mice is slightly decreased in normal hosing condition. Interestingly, UCP1 was downregulated in BAT of HDAC6 knockout mice, which extensively linked mitochondrial thermogenesis. Mechanistically, we showed that cAMP-PKA signaling plays a key role in HDAC6-dependent UCP1 expression. Notably, the size of brown adipocytes and lipid droplets in HDAC6 knockout BAT is increased. Taken together, our findings suggested that HDAC6 contributes to mitochondrial thermogenesis in BAT by increasing UCP1 expression through cAMP-PKA signaling pathway.

Brown adipose Vanin-1 is required for the maintenance of mitochondrial homeostasis and prevents diet-induced metabolic dysfunction.

BACKGROUND: Energy-dissipating brown adipocytes have significant potential for improving systemic metabolism. Vanin-1, a membrane-bound pantetheinase, is involved in various biological processes in mice. However, its role in BAT mitochondrial function is still unclear. In this study, we aimed to elucidate the impact of Vanin-1 on BAT function and contribution during overnutrition-induced obesity. METHODS: Vanin-1 expression was analyzed in different adipose depots in mice. The cellular localization of Vanin-1 was analyzed by confocal microscopy and western blots. Mice lacking Vanin-1 (Vanin-1-/-) were continuously fed either a chow diet or a high-fat diet (HFD) to establish an obesity model. RNA-seq analysis was performed to identify the molecular changes associated with Vanin-1 deficiency during obesity. BAT-specific Vanin-1 overexpression mice were established to determine the effects of Vanin-1 in vivo. Cysteamine treatment was used to examine the effect of enzymatic reaction products of Vanin-1 on BAT mitochondria function in Vanin-1-/- mice. RESULTS: The results indicate that the expression of Vanin-1 is reduced in BAT from both diet-induced and leptin-deficient obese mice. Study on the subcellular location of Vanin-1 shows that it has a mitochondrial localization. Vanin-1 deficiency results in increased adiposity, BAT dysfunction, aberrant mitochondrial structure, and promotes HFD induced-BAT whitening. This is attributed to the impairment of the electron transport chain (ETC) in mitochondria due to Vanin-1 deficiency, resulting in reduced mitochondrial respiration. Overexpression of Vanin-1 significantly enhances energy expenditure and thermogenesis in BAT, renders mice resistant to diet-induced obesity. Furthermore, treatment with cysteamine rescue the mitochondrial dysfunction in Vanin-1-/- mice. CONCLUSIONS: Collectively, these findings suggest that Vanin-1 plays a crucial role in promoting mitochondrial respiration to counteract diet-induced obesity, making it a potential therapeutic target for obesity.

Cell-autonomous control of intracellular temperature by unsaturation of phospholipid acyl chains.

Intracellular temperature affects a wide range of cellular functions in living organisms. However, it remains unclear whether temperature in individual animal cells is controlled autonomously as a response to fluctuations in environmental temperature. Using two distinct intracellular thermometers, we find that the intracellular temperature of steady-state Drosophila S2 cells is maintained in a manner dependent on Δ9-fatty acid desaturase DESAT1, which introduces a double bond at the Δ9 position of the acyl moiety of acyl-CoA. The DESAT1-mediated increase of intracellular temperature is caused by the enhancement of F1Fo-ATPase-dependent mitochondrial respiration, which is coupled with thermogenesis. We also reveal that F1Fo-ATPase-dependent mitochondrial respiration is potentiated by cold exposure through the remodeling of mitochondrial cristae structures via DESAT1-dependent unsaturation of mitochondrial phospholipid acyl chains. Based on these findings, we propose a cell-autonomous mechanism for intracellular temperature control during environmental temperature changes.

AKAP1 Deficiency Attenuates Diet-Induced Obesity and Insulin Resistance by Promoting Fatty Acid Oxidation and Thermogenesis in Brown Adipocytes.

Altering the balance between energy intake and expenditure is a major strategy for treating obesity. Nonetheless, despite the progression in antiobesity drugs on appetite suppression, therapies aimed at increasing energy expenditure are limited. Here, knockout ofAKAP1, a signaling hub on outer mitochondrial membrane, renders mice resistant to diet-induced obesity.AKAP1 knockout significantly enhances energy expenditure and thermogenesis in brown adipose tissues (BATs) of obese mice. Restoring AKAP1 expression in BAT clearly reverses the beneficial antiobesity effect in AKAP1-/- mice. Mechanistically, AKAP1 remarkably decreases fatty acid ß-oxidation (FAO) by phosphorylating ACSL1 to inhibit its activity in a protein-kinase-A-dependent manner and thus inhibits thermogenesis in brown adipocytes. Importantly, AKAP1 peptide inhibitor effectively alleviates diet-induced obesity and insulin resistance. Altogether, the findings demonstrate that AKAP1 functions as a brake of FAO to promote diet-induced obesity, which may be used as a potential therapeutic target for obesity.

Tissue-specific functional interaction between apolipoproteins A1 and E in cold-induced adipose organ mitochondrial energy metabolism.

White (WAT) and brown (BAT) adipose tissue, the two main types of adipose organ, are responsible for lipid storage and non-shivering thermogenesis, respectively. Thermogenesis is a process mediated by mitochondrial uncoupling protein 1 (UCP1) which uncouples oxidative phosphorylation from ATP production, leading to the conversion of free fatty acids to heat. This process can be triggered by exposure to low ambient temperatures, caloric excess, and the immune system. Recently mitochondrial thermogenesis has also been associated with plasma lipoprotein transport system. Specifically, apolipoprotein (APO) E3 is shown to have a bimodal effect on WAT thermogenesis that is highly dependent on its site of expression. Similarly, APOE2 and APOE4 differentially affect BAT and WAT mitochondrial metabolic activity in processes highly modulated by APOA1. Furthermore, the absence of classical APOA1 containing HDL (APOA1-HDL), is associated with no measurable non-shivering thermogenesis in WAT of mice fed high fat diet. Based on these previous observations which indicate important regulatory roles for both APOA1 and APOE in adipose tissue mitochondrial metabolic activity, here we sought to investigate the potential roles of these apolipoproteins in BAT and WAT metabolic activation in mice, following stimulation by cold exposure (7 °C). Our data indicate that APOA1-HDL promotes metabolic activation of BAT only in the presence of very low levels (virtually undetectable) of APOE3-containing HDL (APOE3-HDL), which acts as an inhibitor in this process. In contrast, induction of WAT thermogenesis is subjected to a more complicated regulation which requires the combined presence of both APOA1-HDL and APOE3-HDL.