Involvement of calcium channels in the regulation of adipogenesis

Characterisation of neurogenic lipolytic responses in white adipose tissue ex vivo

BACKGROUND AND PURPOSE

Dysfunction of the autonomic nervous system is associated with cardiovascular dysfunction, including metabolic syndrome and obesity. Understanding mechanisms of neurogenic control of white adipose tissue is key to understanding adipose physiology and pathophysiology, though there is limited research exploring this in adipose tissue using pharmacological tools, as opposed to genetic knockout models.

EXPERIMENTAL APPROACH

Inguinal white adipose tissue from C57BL/6J mice was used in this study. We used immunocytochemistry to determine tissue innervation and glycerol release assays to quantify lipolysis in adipose tissue and isolated adipocytes. The voltage-gated Na+ channel opener veratridine was used to stimulate nervous activity in tissue ex vivo. The role of neurotransmitters and receptors mediating veratridine-evoked lipolysis in adipose tissue was pharmacologically characterised.

KEY RESULTS

Veratridine evoked glycerol release in white adipose tissue but not from isolated adipocytes. This release was abolished by tetrodotoxin and propranolol. Veratridine also induced noradrenaline release from white adipose tissue. Veratridine- and noradrenaline-evoked glycerol release was blocked by the β2-adrenoceptor antagonist ICI-118551 but not by the β1-adrenoceptor antagonist CGP 20712A. Purported β3-adrenoceptor antagonists L-748337 and SR59230A stimulated glycerol release from tissue and from isolated adipocytes. Neither L-748337 or SR59230A antagonised veratridine-evoked glycerol release but SR59230A antagonised noradrenaline-evoked glycerol release. We exclude contributions of sensory neuropeptides and the autonomic neurotransmitters neuropeptide Y and ATP.

CONCLUSION AND IMPLICATIONS

Neurogenic lipolytic responses can be measured in white adipose tissue ex vivo using veratridine to stimulate nerve activity. The lipolytic responses are mediated by β2-adrenoceptor activation. This study provides the first evidence of neurogenic lipolysis in tissue ex vivo.

Fulvic acid inhibits the differentiation of 3T3-L1 adipocytes by activating the Ca2+/CaMKⅡ/AMPK pathway

Type 2 diabetes increases the risk of developing obesity. Although fulvic acid alleviates back fat thickness in pigs, the mechanism underlying its anti-obesity effect remains unclear. Therefore, we investigated the anti-obesity mechanism of fulvic acid using 3T3-L1 adipocytes. We examined the effects of fulvic acid on adipocyte differentiation, cell viability, and lipid accumulation using molecular techniques. Fulvic acid treatment significantly decreased intracellular lipid accumulation in 3T3-L1 cells during the differentiation compared with that in the control group. Western blotting revealed fulvic acid-induced downregulated expression of the adipocyte differentiation-related markers peroxisome proliferator-activated receptor gamma, CCAAT/enhancer-binding protein alpha, and sterol regulatory element-binding protein 1. The fulvic acid treatment decreased the expression of the lipid uptake-related markers fatty acid-binding protein 4 and the cluster of differentiation 36 in 3T3-L1 cells. Moreover, fulvic acid significantly increased cytosolic Ca2+ concentration via Ca2+ sequestration from the endoplasmic reticulum, enhanced Ca2+/calmodulin-dependent protein kinase II (CaMKII) activity, and upregulated AMP-activated protein kinase (AMPK), thereby reducing adipocyte differentiation. Conclusively, fulvic acid attenuates adipocyte differentiation by activating the Ca2+/CaMKⅡ/AMPK pathway, suggesting its anti-obesity potential.

TRPV4 modulation affects mitochondrial parameters in adipocytes and its inhibition upregulates lipid accumulation

Enhanced lipid-droplet formation by adipocytes is a complex process and relevant for obesity. Using knock-out animals, involvement of TRPV4, a thermosensitive ion channel in the obesity has been proposed. However, exact role/s of TRPV4 in adipogenesis and obesity remain unclear and contradictory. Here we used in vitro culture of 3T3L-1 preadipocytes and primary murine-mesenchymal stem cells as model systems, and a series of live-cell-imaging to analyse the direct involvement of TRPV4 exclusively at the adipocytes that are free from other complex signalling as expected in in-vivo condition. Functional TRPV4 is endogenously expressed in pre- and in mature-adipocytes. Pharmacological inhibition of TRPV4 enhances differentiation of preadipocytes to mature adipocytes, increases expression of adipogenic and lipogenic genes, enhances cholesterol, promotes bigger lipid-droplet formation and reduces the lipid droplet temperature. On the other hand, TRPV4 activation enhanced the browning of adipocytes with increased UCP-1 levels. TRPV4 regulates mitochondrial-temperature, Ca2+-load, ATP, superoxides, cardiolipin, membrane potential (ΔΨm), and lipid-mitochondrial contact sites. TRPV4 also regulates the extent of actin fibres, affecting the cells mechanosensing ability. These findings link TRPV4-mediated mitochondrial changes in the context of lipid-droplet formation involved in adipogenesis and confirm the direct involvement of TRPV4 in adipogenesis. These findings may have broad implication in treating adipogenesis and obesity in future.

Glial maturation factor-β deficiency prevents oestrogen deficiency-induced bone loss by remodelling the actin network to suppress adipogenesis of bone marrow mesenchymal stem cells

An imbalance between the adipogenesis and osteogenesis of bone marrow mesenchymal stem cells (BMSCs) is considered the basic pathogenesis of osteoporosis. Although actin cytoskeleton remodelling plays a crucial role in the differentiation of BMSCs, the role of actin cytoskeleton remodelling in the adipogenesis of BMSCs and postmenopausal osteoporosis (PMOP) has remained elusive. Glia maturation factor-beta (GMFB) has a unique role in remodelling the polymerization/depolymerization cycles of actin. We observed that GMFB expression was increased in bone tissue from both ovariectomized (OVX) rats and PMOP patients. GMFB knockout inhibited the accumulation of bone marrow adipocytes and increased bone mass in the OVX rat model. The inhibition of adipocyte differentiation in GMFB knockout BMSCs was mediated via actin cytoskeleton remodelling and the Ca2+-calcineurin-NFATc2 axis. Furthermore, we found that GMFB shRNA treatment in vivo had favourable effects on osteoporosis induced by OVX. Together, these findings suggest a pathological association of the GMFB with PMOP and highlight the potential of the GMFB as a therapeutic target for osteoporosis patients.

A multitissue transcriptomic analysis reveals a potential mechanism whereby Brevibacillus laterosporus S62-9 promotes broiler growth

Brevibacillus laterosporus S62-9 has been shown to improve broiler growth performance and immunity. In the present study, we aimed to evaluate the effects of B. laterosporus S62-9 on the immunity and lipid metabolism of broilers by means of transcriptomic analysis. A total of 160 1-day-old broilers were randomly allocated to a S62-9 group, the diet of which was supplemented with 106 CFU/g B. laterosporus S62-9 daily, and a control group, which was not. After 42 d of feeding, the broilers in the S62-9 group had higher body mass (7.2%) and feed conversion ratio (5.19%) than the control group. Supplementation with B. laterosporus S62-9 resulted in lower serum total cholesterol and low-density lipoprotein-cholesterol concentrations and higher high-density lipoprotein-cholesterol concentrations. An analysis of the fatty acid composition of the broiler's thigh muscles revealed that the proportions of the unsaturated fatty acids myristoleic acid (C14:1) and arachidonic acid (C20:1) were higher for birds in the S62-9 group. Transcriptomic analysis also showed an upregulation of immunity-related genes in the S62-9 group. Gene Ontology functional enrichment analysis showed that the mitogen-activated protein kinase pathway was enriched in the liver, the defense response was enriched in the duodenum, and immunoglobulin-related entries were enriched in the jejunum of the S62-9 group. Furthermore, the expression of key genes involved in unsaturated fatty acid synthesis (SCD, encoding stearoyl-CoA desaturase) and fatty acid metabolism (HACD2, encoding 3-hydroxyacyl-CoA dehydratase 2) was upregulated in the liver, and the expression of genes associated with fat biosynthesis and accumulation, such as PLIN1, encoding perilipin 1, and FABP4, encoding fatty acid binding protein 4, was upregulated in the ileum of the birds in the S62-9 group. In summary, supplementation with B. laterosporus S62-9 could improve immune defense and the fatty acid metabolism of broiler chickens, thereby enhancing their disease resistance and promoting growth and development.

Innervation of adipocytes is limited in mouse perivascular adipose tissue

Perivascular adipose tissue (PVAT) regulates vascular tone by releasing anticontractile factors. These anticontractile factors are driven by processes downstream of adipocyte stimulation by norepinephrine; however, whether norepinephrine originates from neural innervation or other sources is unknown. The goal of this study was to test the hypothesis that neurons innervating PVAT provide the adrenergic drive to stimulate adipocytes in aortic and mesenteric perivascular adipose tissue (aPVAT and mPVAT), and white adipose tissue (WAT). Healthy male and female mice (8-13 wk) were used in all experiments. Expression of genes associated with synaptic transmission were quantified by qPCR and adipocyte activity in response to neurotransmitters and neuron depolarization was assessed in AdipoqCre+;GCaMP5g-tdTf/WT mice. Immunostaining, tissue clearing, and transgenic reporter lines were used to assess anatomical relationships between nerves and adipocytes. Although synaptic transmission component genes are expressed in adipose tissues (aPVAT, mPVAT, and WAT), strong nerve stimulation with electrical field stimulation does not significantly trigger calcium responses in adipocytes. However, norepinephrine consistently elicits strong calcium responses in adipocytes from all adipose tissues studied. Bethanechol induces minimal adipocyte responses. Imaging neural innervation using various techniques reveals that nerve fibers primarily run alongside blood vessels and rarely branch into the adipose tissue. Although nerve fibers are associated with blood vessels in adipose tissue, they demonstrate limited anatomical and functional interactions with adjacent adipocytes, challenging the concept of classical innervation. These findings dispute the significant involvement of neural input in regulating PVAT adipocyte function and emphasize alternative mechanisms governing adrenergic-driven anticontractile functions of PVAT.NEW & NOTEWORTHY This study challenges prevailing views on neural innervation in perivascular adipose tissue (PVAT) and its role in adrenergic-driven anticontractile effects on vasculature. Contrary to existing paradigms, limited anatomical and functional connections were found between PVAT nerve fibers and adipocytes, underscoring the importance of exploring alternative mechanistic pathways. Understanding the mechanisms involved in PVAT's anticontractile effects is critical for developing potential therapeutic interventions against dysregulated vascular tone, hypertension, and cardiovascular disease.

Mechanobiology of Adipocytes

The growing obesity epidemic necessitates increased research on adipocyte and adipose tissue function and disease mechanisms that progress obesity. Historically, adipocytes were viewed simply as storage for excess energy. However, recent studies have demonstrated that adipocytes play a critical role in whole-body homeostasis, are involved in cell communication, experience forces in vivo, and respond to mechanical stimuli. Changes to the adipocyte mechanical microenvironment can affect function and, in some cases, contribute to disease. The aim of this review is to summarize the current literature on the mechanobiology of adipocytes. We reviewed over 100 papers on how mechanical stress is sensed by the adipocyte, the effects on cell behavior, and the use of cell culture scaffolds, particularly those with tunable stiffness, to study adipocyte behavior, adipose cell and tissue mechanical properties, and computational models. From our review, we conclude that adipocytes are responsive to mechanical stimuli, cell function and adipogenesis can be dictated by the mechanical environment, the measurement of mechanical properties is highly dependent on testing methods, and current modeling practices use many different approaches to recapitulate the complex behavior of adipocytes and adipose tissue. This review is intended to aid future studies by summarizing the current literature on adipocyte mechanobiology.

Sex-specific sequels of early life stress on serine/threonine kinase activity in visceral adipose tissue from obese mice

Adverse childhood experiences (ACEs) are an established independent risk factor for chronic disease including obesity and hypertension; however, only women exposed to multiple ACEs show a positive relationship with BMI. Our lab has reported that maternal separation and early weaning (MSEW), a mouse model of early life stress, induces sex-specific mechanisms underlying greater blood pressure response to a chronic high fat diet (HF). Specifically, female MSEW mice fed a HF display exacerbated perigonadal white adipose tissue (pgWAT) expansion and a metabolic syndrome-like phenotype compared to control counterparts, whereas hypertension is caused by sympathoactivation in male MSEW mice. Thus, this study aimed to determine whether there is a sex-specific serine/threonine kinase (STKA) activity in pgWAT adipose tissue associated with early life stress. Frozen pgWAT was collected from MSEW and control, male and female mice fed a HF to assess STKA activity using the Pamstation12 instrument. Overall, MSEW induces significant reduction of 7 phosphokinases (|Z| >=1.5) in females (QIK, MLK, PKCH, MST, STE7, PEK, FRAY) and 5 in males (AKT, SGK, P38, MARK, CDK), while 15 were downregulated in both sexes (DMPK, PKA, PKG, RSK, PLK, DYRK, NMO, CAMK1, JNK, PAKA, RAD53, ERK, PAKB, PKD, PIM, AMPK). This data provides new insights into the sex-specific dysregulation of the molecular network controlling cellular phosphorylation signals in visceral adipose tissue and identifies possible target phosphokinases implicated in adipocyte hypertrophy as a result of exposure to early life stress. Identifying functional metabolic signatures is critical to elucidate the underlying molecular mechanisms behind the sex-specific obesity risk associated with early life stress.

Cabergoline as a Novel Strategy for Post-Pregnancy Breast Cancer Prevention in Mice and Human

Post-pregnancy breast cancer often carries a poor prognosis, posing a major clinical challenge. The increasing trend of later-life pregnancies exacerbates this risk, highlighting the need for effective chemoprevention strategies. Current options, limited to selective estrogen receptor modulators, aromatase inhibitors, or surgical procedures, offer limited efficacy and considerable side effects. Here, we report that cabergoline, a dopaminergic agonist, reduces the risk of breast cancer post-pregnancy in a Brca1/P53-deficient mouse model, with implications for human breast cancer prevention. We show that a single dose of cabergoline administered post-pregnancy significantly delayed the onset and reduced the incidence of breast cancer in Brca1/P53-deficient mice. Histological analysis revealed a notable acceleration in post-lactational involution over the short term, characterized by increased apoptosis and altered gene expression related to ion transport. Over the long term, histological changes in the mammary gland included a reduction in the ductal component, decreased epithelial proliferation, and a lower presence of recombinant Brca1/P53 target cells, which are precursors of tumors. These changes serve as indicators of reduced breast cancer susceptibility. Additionally, RNA sequencing identified gene expression alterations associated with decreased proliferation and mammary gland branching. Our findings highlight a mechanism wherein cabergoline enhances the protective effect of pregnancy against breast cancer by potentiating postlactational involution. Notably, a retrospective cohort study in women demonstrated a markedly lower incidence of post-pregnancy breast cancer in those treated with cabergoline compared to a control group. Our work underscores the importance of enhancing postlactational involution as a strategy for breast cancer prevention, and identifies cabergoline as a promising, low-risk option in breast cancer chemoprevention. This strategy has the potential to revolutionize breast cancer prevention approaches, particularly for women at increased risk due to genetic factors or delayed childbirth, and has wider implications beyond hereditary breast cancer cases.

The role of TRPV ion channels in adipocyte differentiation: What is the evidence?

Obesity is a complex disorder, and the incidence of obesity continues to rise at an alarming rate worldwide. In particular, the growing incidence of overweight and obesity in children is a major health concern. However, the underlying mechanisms of obesity remain unclear and the efficacy of several approaches for weight loss is limited. As an important calcium-permeable temperature-sensitive cation channel, transient receptor potential vanilloid (TRPV) ion channels directly participate in thermo-, mechano-, and chemosensory responses. Modulation of TRPV ion channel activity can alter the physiological function of the ion channel, leading to neurodegenerative diseases, chronic pain, cancer, and skin disorders. In recent years, increasing studies have demonstrated that TRPV ion channels are abundantly expressed in metabolic organs, including the liver, adipose tissue, skeletal muscle, pancreas, and central nervous system, which has been implicated in various metabolic diseases, including obesity and diabetes mellitus. In addition, as an important process for the pathophysiology of adipocyte metabolism, adipocyte differentiation plays a critical role in obesity. In this review, we focus on the role of TRPV ion channels in adipocyte differentiation to broaden the ideas for prevention and control strategies for obesity.

Genome-Wide Association (GWAS) Applied to Carcass and Meat Traits of Nellore Cattle

The meat market has enormous importance for the world economy, and the quality of the product offered to the consumer is fundamental for the success of the sector. In this study, we analyzed a database which contained information on 2470 animals from a commercial farm in the state of São Paulo, Brazil. Of this total, 2181 animals were genotyped, using 777,962 single-nucleotide polymorphisms (SNPs). After quality control analysis, 468,321 SNPs provided information on the number of genotyped animals. Genome-wide association analyses (GWAS) were performed for the characteristics of the rib eye area (REA), subcutaneous fat thickness (SFT), shear force at 7 days' ageing (SF7), and intramuscular fat (IMF), with the aid of the single-step genomic best linear unbiased prediction (ssGBLUP) method, with the purpose of identifying possible genomic windows (~1 Mb) responsible for explaining at least 0.5% of the genetic variance of the traits under analysis (≥0.5%). These genomic regions were used in a gene search and enrichment analyses using MeSH terms. The distributed heritability coefficients were 0.14, 0.20, 0.18, and 0.21 for REA, SFT, SF7, and IMF, respectively. The GWAS results indicated significant genomic windows for the traits of interest in a total of 17 chromosomes. Enrichment analyses showed the following significant terms (FDR ≤ 0.05) associated with the characteristics under study: for the REA, heat stress disorders and life cycle stages; for SFT, insulin and nonesterified fatty acids; for SF7, apoptosis and heat shock proteins (HSP27); and for IMF, metalloproteinase 2. In addition, KEGG (Kyoto encyclopedia of genes and genomes) enrichment analysis allowed us to highlight important metabolic pathways related to the studied phenotypes, such as the growth hormone synthesis, insulin-signaling, fatty acid metabolism, and ABC transporter pathways. The results obtained provide a better understanding of the molecular processes involved in the expression of the studied characteristics and may contribute to the design of selection strategies and future studies aimed at improving the productivity of Nellore cattle.

Type 3 IP3 receptor: Its structure, functions, and related disease implications

Cell-fate decisions depend on the precise and strict regulation of multiple signaling molecules and transcription factors, especially intracellular Ca2+ homeostasis and dynamics. Type 3 inositol 1,4,5-triphosphate receptor (IP3R3) is an a tetrameric channel that can mediate the release of Ca2+ from the endoplasmic reticulum (ER) in response to extracellular stimuli. The gating of IP3R3 is regulated not only by ligands but also by other interacting proteins. To date, extensive research conducted on the basic structure of IP3R3, as well as its regulation by ligands and interacting proteins, has provided novel perspectives on its biological functions and pathogenic mechanisms. This review aims to discuss recent advancements in the study of IP3R3 and provides a comprehensive overview of the relevant literature pertaining to its structure, biological functions, and pathogenic mechanisms.

Regulation of myogenesis and adipogenesis by the electromagnetic perceptive gene

Obesity has been increasing in many regions of the world, including Europe, USA, and Korea. To manage obesity, we should consider it as a disease and apply therapeutic methods for its treatment. Molecular and therapeutic approaches for obesity management involve regulating biomolecules such as DNA, RNA, and protein in adipose-derived stem cells to prevent to be fat cells. Multiple factors are believed to play a role in fat differentiation, with one of the most effective factor is Ca2+. We recently reported that the electromagnetic perceptive gene (EPG) regulated intracellular Ca2+ levels under various electromagnetic fields. This study aimed to investigate whether EPG could serve as a therapeutic method against obesity. We confirmed that EPG serves as a modulator of Ca2+ levels in primary adipose cells, thereby regulating several genes such as CasR, PPARγ, GLU4, GAPDH during the adipogenesis. In addition, this study also identified EPG-mediated regulation of myogenesis that myocyte transcription factors (CasR, MyoG, MyoD, Myomaker) were changed in C2C12 cells and satellite cells. In vivo experiments carried out in this study confirmed that total weight/ fat/fat accumulation were decreased and lean mass was increased by EPG with magnetic field depending on age of mice. The EPG could serve as a potent therapeutic agent against obesity.

Exploring the association between circRNA expression and pediatric obesity based on a case-control study and related bioinformatics analysis

OBJECTIVE

Our present study utilized case-control research to explore the relationship between specific circRNAs and pediatric obesity through a literature review and bioinformatics and to predict their possible biological functions, providing ideas for epigenetic mechanism studies of pediatric obesity.

METHODS

CircRNAs related to pediatric obesity were preliminarily screened by a literature review and qRT-PCR. CircRNA expression in children with obesity (n = 75) and control individuals (n = 75) was confirmed with qRT-PCR in a case-control study. This was followed by bioinformatics analyses, such as GO analysis, KEGG pathway analysis, and ceRNA network construction. Multivariate logistic regression was utilized to analyze the effects of circRNAs on obesity. A receiver operating characteristic (ROC) curve was also drawn to explore the clinical application value of circRNAs in pediatric obesity.

RESULTS

Has_circ_0046367 and hsa_circ_0000284 were separately validated to be statistically downregulated and upregulated, respectively, in the peripheral blood mononuclear cells of children with obesity and revealed as independent indicators of increased CHD risk [hsa_circ_0046367 (OR = 0.681, 95% CI: 0.480 ~ 0.967) and hsa_circ_0000284 (OR = 1.218, 95% CI: 1.041 ~ 1.424)]. The area under the ROC curve in the combined analysis of hsa_circ_0046367 and hsa_circ_0000284 was 0.706 (95% CI: 0.623 ~ 0.789). Enrichment analyses revealed that these circRNAs were actively involved in neural plasticity mechanisms, cell secretion and signal regulation.

CONCLUSION

The present research revealed that low expression of hsa_circ_0046367 and high expression of hsa_circ_0000284 are risk factors for pediatric obesity and that neural plasticity mechanisms are closely related to obesity.

Rebamipide treatment ameliorates obesity phenotype by regulation of immune cells and adipocytes

Obesity is a medical term used to describe an over-accumulation of adipose tissue. It causes abnormal physiological and pathological processes in the body. Obesity is associated with systemic inflammation and abnormalities in immune cell function. Rebamipide, an amino acid derivative of 2-(1H)-quinolinone, has been used as a therapeutic for the protection from mucosal damage. Our previous studies have demonstrated that rebamipide treatment regulates lipid metabolism and inflammation, leading to prevention of weight gain in high-fat diet mice. In this study, mice were put on a high calorie diet for 11 weeks while receiving injections of rebamipide. Rebamipide treatment reduced the body weight, liver weight and blood glucose levels compared to control mice and reduced both glucose and insulin resistance. Fat accumulation has been shown to cause pro-inflammatory activity in mice. Treatment with rebamipide decreased the prevalence of inflammatory cells such as Th2, Th17 and M1 macrophages and increased anti-inflammatory Treg and M2 macrophages in epididymal fat tissue. Additionally, rebamipide addition inhibited adipocyte differentiation in 3T3-L1 cell lines. Taken together, our study demonstrates that rebamipide treatment is a novel and effective method to prevent diet-induced obesity.

Growth Hormone Improves Adipose Tissue Browning and Muscle Wasting in Mice with Chronic Kidney Disease-Associated Cachexia

Cachexia associated with chronic kidney disease (CKD) has been linked to GH resistance. In CKD, GH treatment enhances muscular performance. We investigated the impact of GH on cachexia brought on by CKD. CKD was induced by 5/6 nephrectomy in c57BL/6J mice. After receiving GH (10 mg/kg/day) or saline treatment for six weeks, CKD mice were compared to sham-operated controls. GH normalized metabolic rate, increased food intake and weight growth, and improved in vivo muscular function (rotarod and grip strength) in CKD mice. GH decreased uncoupling proteins (UCP)s and increased muscle and adipose tissue ATP content in CKD mice. GH decreased lipolysis of adipose tissue by attenuating expression and protein content of adipose triglyceride lipase and protein content of phosphorylated hormone-sensitive lipase in CKD mice. GH reversed the increased expression of beige adipocyte markers (UCP-1, CD137, Tmem26, Tbx1, Prdm16, Pgc1α, and Cidea) and molecules implicated in adipose tissue browning (Cox2/Pgf2α, Tlr2, Myd88, and Traf6) in CKD mice. Additionally, GH normalized the molecular markers of processes connected to muscle wasting in CKD, such as myogenesis and muscle regeneration. By using RNAseq, we previously determined the top 12 skeletal muscle genes differentially expressed between mice with CKD and control animals. These 12 genes' aberrant expression has been linked to increased muscle thermogenesis, fibrosis, and poor muscle and neuron regeneration. In this study, we demonstrated that GH restored 7 of the top 12 differentially elevated muscle genes in CKD mice. In conclusion, GH might be an effective treatment for muscular atrophy and browning of adipose tissue in CKD-related cachexia.

Ferroptosis, a Rising Force against Renal Fibrosis

Ferroptosis is a type of programmed cell death characterized by iron overload, oxidative stress, imbalance in lipid repair, and mitochondria-specific pathological manifestations. Growing number of molecular mechanisms and signaling pathways have been found to be involved in ferroptosis progression, including iron metabolism, amino acid metabolism, lipid metabolism, and energy metabolism. It is worth noting that ferroptosis is involved in the progression of fibrotic diseases such as liver cirrhosis, cardiomyopathy, and idiopathic pulmonary fibrosis, and inhibition of ferroptosis has acquired beneficial outcomes in rodent models, while studies on ferroptosis and renal fibrosis remains limited. Recent studies have revealed that targeting ferroptosis can effectively mitigate chronic kidney injury and renal fibrosis. Moreover, myofibroblasts suffer from ferroptosis during fiber and extracellular matrix deposition in the fibrotic cascade reaction and pharmacological modulation of ferroptosis shows great therapeutic effect on renal fibrosis. Here, we summarize the latest molecular mechanisms of ferroptosis from high-quality studies and review its therapeutic potential in renal fibrosis.

PIEZO1 mechanoreceptor activation reduces adipogenesis in perivascular adipose tissue preadipocytes

During hypertension, vascular remodeling allows the blood vessel to withstand mechanical forces induced by high blood pressure (BP). This process is well characterized in the media and intima layers of the vessel but not in the perivascular adipose tissue (PVAT). In PVAT, there is evidence for fibrosis development during hypertension; however, PVAT remodeling is poorly understood. In non-PVAT depots, mechanical forces can affect adipogenesis and lipogenic stages in preadipocytes. In tissues exposed to high magnitudes of pressure like bone, the activation of the mechanosensor PIEZO1 induces differentiation of progenitor cells towards osteogenic lineages. PVAT's anatomical location continuously exposes it to forces generated by blood flow that could affect adipogenesis in normotensive and hypertensive states. In this study, we hypothesize that activation of PIEZO1 reduces adipogenesis in PVAT preadipocytes. The hypothesis was tested using pharmacological and mechanical activation of PIEZO1. Thoracic aorta PVAT (APVAT) was collected from 10-wk old male SD rats (n=15) to harvest preadipocytes that were differentiated to adipocytes in the presence of the PIEZO1 agonist Yoda1 (10 µM). Mechanical stretch was applied with the FlexCell System at 12% elongation, half-sine at 1 Hz simultaneously during the 4 d of adipogenesis (MS+, mechanical force applied; MS-, no mechanical force used). Yoda1 reduced adipogenesis by 33% compared with CON and, as expected, increased cytoplasmic Ca2+ flux. MS+ reduced adipogenesis efficiency compared with MS-. When Piezo1 expression was blocked with siRNA [siPiezo1; NC=non-coding siRNA], the anti-adipogenic effect of Yoda1 was reversed in siPiezo1 cells but not in NC; in contrast, siPiezo1 did not alter the inhibitory effect of MS+ on adipogenesis. These data demonstrate that PIEZO1 activation in PVAT reduces adipogenesis and lipogenesis and provides initial evidence for an adaptive response to excessive mechanical forces in PVAT during hypertension.

Transcriptome analysis provides insight into deltamethrin-induced fat accumulation in 3T3-L1 adipocytes

Previously, deltamethrin (a Type-II pyrethroid) has been reported to increase triglyceride (fat) accumulation in adipocytes, while its underlying molecular mechanism is not fully determined. The aim of this study was to further investigate the molecular mechanisms of deltamethrin induced fat accumulation in murine 3T3-L1 adipocytes. Consistent to previous reports, deltamethrin (10 μM) significantly promoted adipogenesis in 3T3-L1 adipocytes. RNA sequencing (RNA-seq) results showed that 721 differentially expressed genes (DEGs) were identified after deltamethrin treatment, involving in 58 Functional groups of Gene Ontology (GO) and 255 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Several key functional groups regulating adipogenesis, such as fat cell differentiation (Igf1, Snai2, Fgf10, and Enpp1) and cytosolic calcium ion concentration (Nos1, Cxcl1, and Ngf) were significantly enriched. Collectively, these results suggest that the promotion of adipogenesis by deltamethrin was attributed to an obesogenic global transcriptomic response, which provides further understanding of the underlying mechanisms of deltamethrin-induced fat accumulation.

MS4A15 drives ferroptosis resistance through calcium-restricted lipid remodeling

Ferroptosis is an iron-dependent form of cell death driven by biochemical processes that promote oxidation within the lipid compartment. Calcium (Ca²⁺) is a signaling molecule in diverse cellular processes such as migration, neurotransmission, and cell death. Here, we uncover a crucial link between ferroptosis and Ca²⁺ through the identification of the novel tetraspanin MS4A15. MS4A15 localizes to the endoplasmic reticulum, where it blocks ferroptosis by depleting luminal Ca²⁺ stores and reprogramming membrane phospholipids to ferroptosis-resistant species. Specifically, prolonged Ca²⁺ depletion inhibits lipid elongation and desaturation, driving lipid droplet dispersion and formation of shorter, more saturated ether lipids that protect phospholipids from ferroptotic reactive species. We further demonstrate that increasing luminal Ca²⁺ levels can preferentially sensitize refractory cancer cell lines. In summary, MS4A15 regulation of anti-ferroptotic lipid reservoirs provides a key resistance mechanism that is distinct from antioxidant and lipid detoxification pathways. Manipulating Ca²⁺ homeostasis offers a compelling strategy to balance cellular lipids and cell survival in ferroptosis-associated diseases.

An update on brown adipose tissue and obesity intervention: Function, regulation and therapeutic implications

Overweight and obesity have become a world-wide problem. However, effective intervention approaches are limited. Brown adipose tissue, which helps maintain body temperature and contributes to thermogenesis, is dependent on uncoupling protein1. Over the last decade, an in-creasing number of studies have found that activating brown adipose tissue and browning of white adipose tissue can protect against obesity and obesity-related metabolic disease. Brown adipose tissue has gradually become an appealing therapeutic target for the prevention and re-versal of obesity. However, some important issues remain unresolved. It is not certain whether increasing brown adipose tissue activity is the cause or effect of body weight loss or what the risks might be for sympathetic nervous system-dependent non-shivering thermogenesis. In this review, we comprehensively summarize approaches to activating brown adipose tissue and/or browning white adipose tissue, such as cold exposure, exercise, and small-molecule treatment. We highlight the functional mechanisms of small-molecule treatment and brown adipose tissue transplantation using batokine, sympathetic nervous system and/or gut microbiome. Finally, we discuss the causality between body weight loss induced by bariatric surgery, exercise, and brown adipose tissue activity.

The Synthesis of Europium-Doped Calcium Carbonate by an Eco-Method as Free Radical Generator Under Low-Intensity Ultrasonic Irradiation for Body Sculpture

Body sculpture is a common method to remove excessive fat. The diet and exercise are the first suggestion to keep body shape; however, those are difficult to keep adherence. Ultrasound has been developed for fat ablation; however, it could only serve as the side treatment along with liposuction. In the study, a sonosensitizer of europium-doped calcium carbonate (CaCO₃: Eu) would be synthesized by an eco-method and combined with low-intensity ultrasound for lipolysis. The crystal structure of CaCO₃: Eu was identified by x-ray diffractometer (XRD). The morphology of CaCO₃: Eu was analyzed by scanning electron microscope (SEM). The chemical composition of CaCO₃: Eu was evaluated by energy-dispersed spectrophotometer (EDS) and inductively coupled plasma mass spectrometer (ICP-MS). The electronic diffraction pattern was to further check crystal structure of the synthesized individual grain by transmission electron microscope (TEM). The particle size was determined by Zeta-sizer. Water-soluble tetrazolium salt (WST-1) were used to evaluate the cell viability. Chloromethyl-2′,7′-dichlorofluorescein diacetate (CM-H₂DCFDA) and live/dead stain were used to evaluate feasibility in vitro. SD-rat was used to evaluate the safety and efficacy in vivo. The results showed that CaCO₃: Eu had good biocompatibility and could produce reactive oxygen species (ROS) after treated with low-intensity ultrasound. After 4-weeks, the CaCO₃: Eu exposed to ultrasound irradiation on SD rats could significantly decrease body weight, waistline, and subcutaneous adipose tissue. We believe that ROS from sonoluminescence, CO₂-bomb and locally increasing Ca²⁺ level would be three major mechanisms to remove away adipo-tissue and inhibit adipogenesis. We could say that the combination of the CaCO₃: Eu and low-intensity ultrasound would be a non-invasive treatment for the body sculpture.

Signaling Targets Related to Antiobesity Effects of Capsaicin: A Scoping Review

The search for new antiobesogenic agents is increasing because of the current obesity pandemic. Capsaicin (Caps), an exogenous agonist of the vanilloid receptor of transient potential type 1 (TRPV1), has shown promising results in the treatment of obesity. This scoping review aims to verify the pathways mediating the effects of Caps in obesity and the different methods adopted to identify these pathways. The search was carried out using data from the EMBASE, MEDLINE (PubMed), Web of Science, and SCOPUS databases. Studies considered eligible evaluated the mechanisms of action of Caps in obesity models or cell types involved in obesity. Nine studies were included and 100% (n = 6) of the in vivo studies showed a high risk of bias. Of the 9 studies, 66.6% (n = 6) administered Caps orally in the diet and 55.5% (n = 5) used a concentration of Caps of 0.01% in the diet. In vitro, the most tested concentration was 1 μM (88.9%; n = 8). Capsazepine was the antagonist chosen by 66.6% (n = 6) of the studies. Seven studies (77.8%) linked the antiobesogenic effects of Caps to TRPV1 activation and 3 (33.3%) indicated peroxisome proliferator-activated receptor (PPAR) involvement as an upstream connection to TRPV1, rather than a direct metabolic target of Caps. The main secondary effects of Caps were lower weight gain (33.3%; n = 3) or loss (22.2%; n = 2), greater improvement in lipid profile (33.3%; n = 3), lower white adipocyte adipogenesis (33.3%; n = 3), browning process activation (44.4%; n = 4), and higher brown adipocyte activity (33.3%; n = 3) compared with those of the control treatment. Some studies have shown that PPAR agonists modulate TRPV1 activity, and no study has evaluated the simultaneous antagonism of these 2 receptors. Consequently, further studies are necessary to elucidate the role of each of these signaling molecules in the antiobesogenic effects of Caps.

Genetic Deletion of KLHL1 Leads to Hyperexcitability in Hypothalamic POMC Neurons and Lack of Electrical Responses to Leptin

Kelch-like 1 (KLHL1) is a neuronal actin-binding protein that modulates voltage-gated calcium channels. The KLHL1 knockout (KO) model displays altered calcium channel expression in various brain regions. We analyzed the electrical behavior of hypothalamic POMC (proopiomelanocortin) neurons and their response to leptin. Leptin's effects on POMC neurons include enhanced gene expression, activation of the ERK1/2 pathway and increased electrical excitability. The latter is initiated by activation of the Jak2-PI3K-PLC pathway, which activates TRPC1/5 (Transient Receptor Potential Cation) channels that in turn recruit T-type channel activity resulting in increased excitability. Here we report over-expression of Ca_V3.1 T-type channels in the hypothalamus of KLHL1 KO mice increased T-type current density and enhanced POMC neuron basal excitability, rendering them electrically unresponsive to leptin. Electrical sensitivity to leptin was restored by partial blockade of T-type channels. The overexpression of hypothalamic T-type channels in POMC neurons may partially contribute to the obese and abnormal feeding phenotypes observed in KLHL1 KO mice.

Time-Dependent Reduction of Calcium Oscillations in Adipose-Derived Stem Cells Differentiating towards Adipogenic and Osteogenic Lineage

Adipose-derived mesenchymal stromal cells (ASCs) are multipotent stem cells which can differentiate into various cell types, including osteocytes and adipocytes. Due to their ease of harvesting, multipotency, and low tumorigenicity, they are a prime candidate for the development of novel interventional approaches in regenerative medicine. ASCs exhibit slow, spontaneous Ca²⁺ oscillations and the manipulation of Ca²⁺ signalling via electrical stimulation was proposed as a potential route for promoting their differentiation in vivo. However, the effects of differentiation-inducing treatments on spontaneous Ca²⁺ oscillations in ASCs are not yet fully characterised. In this study, we used 2-photon live Ca²⁺ imaging to assess the fraction of cells showing spontaneous oscillations and the frequency of the oscillation (measured as interpeak interval—IPI) in ASCs undergoing osteogenic or adipogenic differentiation, using undifferentiated ASCs as controls. The measurements were carried out at 7, 14, and 21 days in vitro (DIV) to assess the effect of time in culture on Ca²⁺ dynamics. We observed that both time and differentiation treatment are important factors associated with a reduced fraction of cells showing Ca²⁺ oscillations, paralleled by increased IPI times, in comparison with untreated ASCs. Both adipogenic and osteogenic differentiation resulted in a reduction in Ca²⁺ dynamics, such as the fraction of cells showing intracellular Ca²⁺ oscillations and their frequency. Adipogenic differentiation was associated with a more pronounced reduction of Ca²⁺ dynamics compared to cells differentiating towards the osteogenic fate. Changes in Ca²⁺ associated oscillations with a specific treatment had already occurred at 7 DIV. Finally, we observed a reduction in Ca²⁺ dynamics over time in untreated ASCs. These data suggest that adipogenic and osteogenic differentiation cell fates are associated with specific changes in spontaneous Ca²⁺ dynamics over time. While this observation is interesting and provides useful information to understand the functional correlates of stem cell differentiation, further studies are required to clarify the molecular and mechanistic correlates of these changes. This will allow us to better understand the causal relationship between Ca²⁺ dynamics and differentiation, potentially leading to the development of novel, more effective interventions for both bone regeneration and control of adipose growth.

Involvement of TRP Channels in Adipocyte Thermogenesis: An Update

Obesity prevalence became a severe global health problem and it is caused by an imbalance between energy intake and expenditure. Brown adipose tissue (BAT) is a major site of mammalian non-shivering thermogenesis or energy dissipation. Thus, modulation of BAT thermogenesis might be a promising application for body weight control and obesity prevention. TRP channels are non-selective calcium-permeable cation channels mainly located on the plasma membrane. As a research focus, TRP channels have been reported to be involved in the thermogenesis of adipose tissue, energy metabolism and body weight regulation. In this review, we will summarize and update the recent progress of the pathological/physiological involvement of TRP channels in adipocyte thermogenesis. Moreover, we will discuss the potential of TRP channels as future therapeutic targets for preventing and combating human obesity and related-metabolic disorders.

Regulatory effects of protein S-acylation on insulin secretion and insulin action

Post-translational modifications (PTMs) such as phosphorylation and ubiquitination are well-studied events with a recognized importance in all aspects of cellular function. By contrast, protein S-acylation, although a widespread PTM with important functions in most physiological systems, has received far less attention. Perturbations in S-acylation are linked to various disorders, including intellectual disability, cancer and diabetes, suggesting that this less-studied modification is likely to be of considerable biological importance. As an exemplar, in this review, we focus on the newly emerging links between S-acylation and the hormone insulin. Specifically, we examine how S-acylation regulates key components of the insulin secretion and insulin response pathways. The proteins discussed highlight the diverse array of proteins that are modified by S-acylation, including channels, transporters, receptors and trafficking proteins and also illustrate the diverse effects that S-acylation has on these proteins, from membrane binding and micro-localization to regulation of protein sorting and protein interactions.

BKCa channel participates in insulin-induced lipid deposition in adipocytes by increasing intracellular calcium

Storing energy in the form of triglyceride (TG) is one of the basic functions of adipose tissue. Large-conductance calcium-activated potassium channels (BK_Ca channels) are expressed in adipose tissue and adipocyte-specific BK_Ca deficiency resists obesity in mice, but the role of BK_Ca channels in lipid deposition and the underlying mechanisms have not been elucidated. In the present study, we generated BK_Ca knockout (KO) rats and performed a transcriptome analysis of adipose tissue. We found that the phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) signaling pathway, which is important for lipid deposition, exhibited the most notable reduction among various signaling pathways in BK_Ca KO rats compared to wild-type rats. Insulin-induced TG deposition, glucose uptake, and Akt (Ser473) phosphorylation were significantly reduced in cultured adipocytes differentiated from adipose-derived stem cells of BK_Ca KO rats. Furthermore, we found that the insulin-induced increase of intracellular calcium resulting from extracellular calcium influx was significantly impaired in BK_Ca KO adipocytes. Finally, insulin activated BK_Ca currents through PI3K, which was independent of Akt and intracellular calcium. The results of this study suggested that BK_Ca channels participate in the insulin signaling pathway and promote TG deposition by increasing extracellular calcium influx in adipocytes.

Whole-slide image analysis outperforms micrograph acquisition for adipocyte size quantification

The distinction between biological processes of adipose tissue expansion is crucial to understanding metabolic derangements, but a robust method for quantifying adipocyte size has yet to be standardized. Here, we compared three methods for histological analysis in situ: one conventional approach using individual micrographs acquired by digital camera, and two with whole-slide image analysis pipelines involving proprietary (Visiopharm) and open-source software (QuPath with a novel ImageJ plugin). We found that micrograph analysis identified 10–40 times fewer adipocytes than whole-slide methods, and this small sample size resulted in high variances that could lead to statistical errors. The agreement of the micrograph method to measure adipocyte area with each of the two whole-slide methods was substantially less (R² of 0.6644 and 0.7125) than between the two whole-slide methods (R² of 0.9402). These inconsistencies were more pronounced in samples from high-fat diet fed mice. While the use of proprietary software resulted in the highest adipocyte count, the lower cost, ease of use, and minimal variances of the open-source software provided a distinct advantage for measuring the number and size of adipocytes. In conclusion, we recommend whole-slide image analysis methods to consistently measure adipocyte area and avoid unintentional errors due to small sample sizes.

Identification of Candidate Genes and Pathways Associated with Obesity-Related Traits in Canines via Gene-Set Enrichment and Pathway-Based GWAS Analysis

The present study aimed to identify causative loci and genes enriched in pathways associated with canine obesity using a genome-wide association study (GWAS). The GWAS was first performed to identify candidate single-nucleotide polymorphisms (SNPs) associated with obesity and obesity-related traits including body weight and blood sugar in 18 different breeds of 153 dogs. A total of 10 and 2 SNPs were found to be significantly (p < 3.74 × 10^-7) associated with body weight and blood sugar, respectively. None of the SNPs were identified to be significantly associated with obesity trait. We subsequently followed up the GWAS analysis with gene-set enrichment and pathway analyses. A gene-set with 1057, 1409, and 1243 SNPs annotated to 449, 933 and 820 genes for obesity, body weight, and blood sugar, respectively was created by sub-setting the GWAS result at a threshold of p < 0.01 for the gene-set enrichment analysis. In total, 84 GO and 21 KEGG pathways for obesity, 114 GO and 44 KEGG pathways for blood sugar, 120 GO and 24 KEGG pathways for body weight were found to be enriched. Among the pathways and GO terms, we highlighted five enriched pathways (Wnt signaling pathway, adherens junction, pathways in cancer, axon guidance, and insulin secretion) and seven GO terms (fat cell differentiation, calcium ion binding, cytoplasm, nucleus, phospholipid transport, central nervous system development, and cell surface) that were found to be shared among all the traits. Our data provide insights into the genes and pathways associated with obesity and obesity-related traits.

A Transcriptomic Analysis Reveals Novel Patterns of Gene Expression During 3T3-L1 Adipocyte Differentiation

Background

Obesity is characterized by increased adipose tissue mass that results from increased fat cell size (hypertrophy) and number (hyperplasia). The molecular mechanisms that govern the regulation and differentiation of adipocytes play a critical role for better understanding of the pathological mechanism of obesity. However, the mechanism of adipocyte differentiation is still unclear.

Objective

The present study aims to compare the gene expression changes during adipocyte differentiation in the transcriptomic level, which may help to better understand the mechanism of adipocyte differentiation.

Methods

RNA sequencing (RNA-seq) technology, GO and KEGG analysis, quantitative RT-PCR, and oil red O staining methods were used in this study.

Results

A lot of genes were up- or down-regulated between each two differentiation stages of 3T3-L1 cells. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that lipid metabolism and oxidation–reduction reaction were mainly involved in the whole process of adipocyte differentiation. Decreased immune response and cell cycle adhesion occurred in the late phase of adipocyte differentiation, which was demonstrated by divergent expression pattern analysis. Moreover, quantitative RT-PCR results showed that the mRNA expression levels of Trpv4, Trpm4, Trpm5, and Trpm7 were significantly decreased in the differentiated adipocytes. On the other hand, the mRNA expression levels of Trpv1, Trpv2, Trpv6, and Trpc1 were significantly increased in the differentiated adipocytes. Besides, the mRNA expressions of TRPV2 and TRPM7 were also significantly increased in subcutaneous white adipose tissue from diet-induced mice. In addition, the activation of TRPM7, TRPV1, and TRPV2 suppressed the differentiation of adipocytes.

Conclusion

These data present the description of transcription profile changes during adipocyte differentiation and provides an in-depth analysis of the possible mechanisms of adipocyte differentiation. These data offer new insight into the understanding of the mechanisms of adipocyte differentiation.