EP4-induced mitochondrial localization and cell migration mediated by CALML6 in human oral squamous cell carcinoma

Lymph node metastasis, primarily caused by the migration of oral squamous cell carcinoma (OSCC) cells, stands as a crucial prognostic marker. We have previously demonstrated that EP4, a subtype of the prostaglandin E2 (PGE2) receptor, orchestrates OSCC cell migration via Ca2+ signaling. The exact mechanisms by which EP4 influences cell migration through Ca2+ signaling, however, is unclear. Our study aims to clarify how EP4 controls OSCC cell migration through this pathway. We find that activating EP4 with an agonist (ONO-AE1-473) increased intracellular Ca2+ levels and the migration of human oral cancer cells (HSC-3), but not human gingival fibroblasts (HGnF). Further RNA sequencing linked EP4 to calmodulin-like protein 6 (CALML6), whose role remains undefined in OSCC. Through protein-protein interaction network analysis, a strong connection is identified between CALML6 and calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2), with EP4 activation also boosting mitochondrial function. Overexpressing EP4 in HSC-3 cells increases experimental lung metastasis in mice, whereas inhibiting CaMKK2 with STO-609 markedly lowers these metastases. This positions CaMKK2 as a potential new target for treating OSCC metastasis. Our findings highlight CALML6 as a pivotal regulator in EP4-driven mitochondrial respiration, affecting cell migration and metastasis via the CaMKK2 pathway.

Brown adipocyte mineralocorticoid receptor deficiency impairs metabolic regulation in diet-induced obese mice

Activation of brown adipose tissue (BAT) contributes to energy dissipation and metabolic health. Although mineralocorticoid receptor (MR) antagonists have been demonstrated to improve metabolism under obesity, the underlying mechanisms remain incompletely understood. We aimed to evaluate the role of BAT MR in metabolic regulation. After 8 weeks of high-fat diet (HFD) feeding, BAT MR KO (BMRKO) mice manifested significantly increased bodyweight, fat mass, serum fasting glucose, and impaired glucose homeostasis compared with littermate control (LC) mice, although insulin resistance and fasting serum insulin were not significantly changed. Metabolic cage experiments showed no change in O2 consumption, CO2 production, or energy expenditure in obese BMRKO mice. RNA sequencing analysis revealed downregulation of genes related to fatty acid metabolism in BAT of BMRKO-HFD mice compared with LC-HFD mice. Moreover, H&E and immunohistochemical staining demonstrated that BMRKO exacerbated HFD-induced macrophage infiltration and proinflammatory genes in epididymal white adipose tissue (eWAT). BMRKO-HFD mice also manifested significantly increased liver weights and hepatic lipid accumulation, an increasing trend of genes related to lipogenesis and lipid uptake, and significantly decreased genes related to lipolytic and fatty acid oxidation in the liver. Finally, the level of insulin-induced AKT phosphorylation was substantially blunted in eWAT but not liver or skeletal muscle of BMRKO-HFD mice compared with LC-HFD mice. These data suggest that BAT MR is required to maintain metabolic homeostasis, likely through its regulation of fatty acid metabolism in BAT and impacts on eWAT and liver.

MicroRNA-17-3p protects against excessive posthypoxic autophagy in H9C2 cardiomyocytes via PTEN-Akt-mTOR signaling pathway

The activity of phosphatase and tensin homolog (PTEN) can be inhibited by miR-17-3p, which results in attenuating myocardial ischemia/reperfusion injury (IRI), however, the mechanism behind this phenomenon is still elusive. Suppression of PTEN leads to augmented protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling strength and constrained autophagy activation, which might be the one mechanism for the ameliorated myocardial IRI. Thus, we tested the hypothesis that miR-17-3p attenuated hypoxia/reoxygenation (H/R)-mediated damage in cardiomyocytes by downregulating excessive autophagy via the PTEN-Akt-mTOR axis. The expression of miR-17-3p was remarkably increased after H/R treatment (6-h hypoxia followed by 6-h reoxygenation; H6/R6), which was concomitant with the increase of the release of lactic acid dehydrogenase (cell injury marker) and the enhancement LC3II/I ratio (autophagy markers) in H9C2 cardiomyocytes. Ectoexpression of miR-17-3p agomir led to remarkable augmentation of miR-17-3p expression and evidently attenuated H/R-mediated cell damage and excessive autophagy. Furthermore, an increase in miR-17-3p expression elicited constrained phosphorylation of PTEN (Ser³⁸⁰ ) while enhanced the phosphorylation of Akt (Thr³⁰⁸ , Ser⁴⁷³ ) and mTOR (Ser⁵³⁶ ) after H/R stimulation. In addition, pretreatment with LY-294002 (an Akt selective inhibitor) and rapamycin (an mTOR selective inhibitor) significantly abrogated the protective function of miR-17-3p on H/R-mediated cell damage and autophagy in H9C2 cardiomyocytes. Taken together, these observations indicated that the enhancement of the PTEN/Akt/mTOR axis and the consequent suppression of autophagy overactivation might represent an underlying mechanism by which miR-17-3p attenuated H/R-mediated damage in H9C2 cells.

Genome-wide association analysis of milk production, somatic cell score, and body conformation traits in Holstein cows

Milk production and body conformation traits are critical economic traits for dairy cows. To understand the basic genetic structure for those traits, a genome wide association study was performed on milk yield, milk fat yield, milk fat percentage, milk protein yield, milk protein percentage, somatic cell score, body form composite index, daily capacity composite index, feed, and leg conformation traits, based on the Illumina Bovine HD100k BeadChip. A total of 57, 12 and 26 SNPs were found to be related to the milk production, somatic cell score and body conformation traits in the Holstein cattle. Genes with pleiotropic effect were also found in this study. Seven significant SNPs were associated with multi-traits and were located on the PLEC, PLEKHA5, TONSL, PTGER4, and LCORL genes. In addition, some important candidate genes, like GPAT3, CEBPB, AGO2, SLC37A1, and FNDC3B, were found to participate in fat metabolism or mammary gland development. These results can be used as candidate genes for milk production, somatic cell score, and body conformation traits of Holstein cows, and are helpful for further gene function analysis to improve milk production and quality.

Mitochondrial regulation and white adipose tissue homeostasis

The important role of mitochondria in the regulation of white adipose tissue (WAT) remodeling and energy balance is increasingly appreciated. The remarkable heterogeneity of the adipose tissue stroma provides a cellular basis to enable adipose tissue plasticity in response to various metabolic stimuli. Regulating mitochondrial function at the cellular level in adipocytes, in adipose progenitor cells (APCs), and in adipose tissue macrophages (ATMs) has a profound impact on adipose homeostasis. Moreover, mitochondria facilitate the cell-to-cell communication within WAT, as well as the crosstalk with other organs, such as the liver, the heart, and the pancreas. A better understanding of mitochondrial regulation in the diverse adipose tissue cell types allows us to develop more specific and efficient approaches to improve adipose function and achieve improvements in overall metabolic health.

Deficiency of telomere-associated repressor activator protein 1 precipitates cardiac aging in mice via p53/PPARα signaling

Background: Telomere shortening and dysfunction may cause metabolic disorders, tissue damage and age-dependent pathologies. However, little is known about the association of telomere-associated protein Rap1 with mitochondrial energy metabolism and cardiac aging. Methods: Echocardiography was performed to detect cardiac structure and function in Rap1^+/+ and Rap1^-/- mice at different ages (3 months, 12 months and 20 months). Telomere length, DNA damage, cardiac senescence and cardiomyocyte size were analyzed using the real-time PCR, Western blotting, senescence associated β-galactosidase assay and wheat germ agglutinin staining, respectively. Western blotting was also used to determine the level of cardiac fatty acid metabolism related key enzymes in mouse and human myocardium. Chromatin immunoprecipitation assay was used to verify the direct link between p53 and PPARα. The p53 inhibitor, Pifithrin-α and PPARα activator WY14643 were utilized to identify the effects of Rap1/p53/PPARα signaling pathway. Results: Telomere was shortened concomitant with extensive DNA damage in aged Rap1^-/- mouse hearts, evidenced by reduced T/S ratios and increased nuclear γH2AX. Meanwhile, the aging-associated phenotypes were pronounced as reflected by altered mitochondrial ultrastructure, enhanced senescence, cardiac hypertrophy and dysfunction. Mechanistically, acetylated p53 and nuclear p53 was enhanced in the Rap1^-/- mouse hearts, concomitant with reduced PPARα. Importantly, p53 directly binds to the promoter of PPARα in mouse hearts and suppresses the transcription of PPARα. In addition, aged Rap1^-/- mice exhibited reduced cardiac fatty acid metabolism. Pifithrin-α alleviated cardiac aging and enhanced fatty acid metabolism in the aged Rap1^-/- mice. Activating PPARα with WY14643 in primarily cultured Rap1^-/- cardiomyocytes restored maximal oxygen consumption rates. Reduced Rap1 expression and impaired p53/PPARα signaling also presented in aged human myocardium. Conclusion: In summary, Rap1 may link telomere biology to fatty acid metabolism and aging-related cardiac pathologies via modulating the p53/PPARα signaling pathway, which could represent a therapeutic target in preventing/attenuating cardiac aging.

Prostaglandin E receptor subtype 4 protects against diabetic cardiomyopathy by modulating cardiac fatty acid metabolism via FOXO1/CD36 signalling

BACKGROUND

Cardiac fatty acid metabolism is essential for maintaining normal cardiac function at baseline and in response to various disease stress, like diabetes. EP4 is widely expressed in cardiomyocytes and has been demonstrated to play a role in cardio function. However, its function in regulating cardiac fatty acid metabolism is remained unknown.

METHODS

Mice were fed with standard chow or high-fat for eight weeks. The effects of EP4 deficiency on cardiac function, cardiomyocytes hypertrophy and myocardial fibrosis were studied. The possible regulatory mechanisms were further investigated.

RESULTS

EP4^-/- mice exhibited concentric hypertrophy and myocardial fibrosis with cardiac energy deprivation due to reduction of fatty acid uptake and inhibition of ATP generation mediated by FOXO1/CD36 signalling. Moreover, pharmacologically activated EP4 alleviated impaired fatty acid transport and insufficient ATP generation in cardiomyocytes.

CONCLUSION

EP4 tightly coordinates the rates of cardiac fatty acid uptake and ATP generation via FOXO1/CD36 signalling axis. Our study provides evidences for the link between EP4 and cardiac fatty acid transport and further pointed out that EP4 could be a potential target for modulating fatty acid metabolism and curbing cardiac tissue-specific impairment of function following diabetes.

Parental SIRT1 Overexpression Attenuate Metabolic Disorders Due to Maternal High-Fat Feeding

Maternal obesity can contribute to the development of obesity and related metabolic disorders in progeny. Sirtuin (SIRT)1, an essential regulator of metabolism and stress responses, has recently emerged as an important modifying factor of developmental programming. In this study, to elucidate the effects of parental SIRT1 overexpression on offspring mechanism, four experimental groups were included: (1) Chow-fed wild-type (WT)-dam × Chow-fed WT-sire; (2) High-fat diet (HFD)-fed WT-dam × Chow-fed WT-sire; (3) HFD-fed hemizygous SIRT1-transgenic (Tg)-dam × Chow-fed WT-sire; and (4) HFD-fed WT dam × Chow-fed Tg-sire. Our results indicate that Tg breeders had lower body weight and fat mass compared to WT counterparts and gave birth to WT offspring with reductions in body weight, adiposity and hyperlipidaemia compared to those born of WT parents. Maternal SIRT1 overexpression also reversed glucose intolerance, and normalised abnormal fat morphology and the expression of dysregulated lipid metabolism markers, including SIRT1. Despite having persistent hepatic steatosis, offspring born to Tg parents showed an improved balance of hepatic glucose/lipid metabolic markers, as well as reduced levels of inflammatory markers and TGF-β/Smad3 fibrotic signalling. Collectively, the data suggest that parental SIRT1 overexpression can ameliorate adverse metabolic programming effects by maternal obesity.

NSAID-induced injury of gastric epithelial cells is reversible: roles of mitochondria, AMP kinase, NGF, and PGE2

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as diclofenac (DFN) and indomethacin (INDO) are extensively used worldwide. Their main side effects are injury of the gastrointestinal tract, including erosions, ulcers, and bleeding. Since gastric epithelial cells (GEPCs) are crucial for mucosal defense and are the major target of injury, we examined the extent to which DFN- and INDO-induced GEPC injury can be reversed by nerve growth factor (NGF), 16,16 dimethyl prostaglandin E2 (dmPGE2), and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), the pharmacological activator of the metabolic sensor AMP kinase (AMPK). Cultured normal rat gastric mucosal epithelial (RGM1) cells were treated with PBS (control), NGF, dmPGE2, AICAR, and/or NSAID (DFN or INDO) for 1-4 h. We examined cell injury by confocal microscopy, cell death/survival using calcein AM, mitochondrial membrane potential using MitoTracker, and phosphorylation of AMPK by Western blotting. DFN and INDO treatment of RGM1 cells for 2 h decreased mitochondrial membrane potential and cell viability. NGF posttreatment (initiated 1 or 2 h after DFN or INDO) reversed the dissipation of mitochondrial membrane potential and cell injury caused by DFN and INDO and increased cell viability versus cells treated for 4 h with NSAID alone. Pretreatment with dmPGE2 and AICAR significantly protected these cells from DFN- and INDO-induced injury, whereas dmPGE2 and AICAR posttreatment (initiated 1 h after NSAID treatment) reversed cell injury and significantly increased cell viability and rescued the cells from NSAID-induced mitochondrial membrane potential reduction. DFN and INDO induce extensive mitochondrial injury and GEPC death, which can be significantly reversed by NGF, dmPGE2, and AICAR.NEW & NOTEWORTHY This study demonstrated that mitochondria are key targets of diclofenac- and indomethacin-induced injury of gastric epithelial cells and that diclofenac and indomethacin injury can be prevented and, importantly, also reversed by treatment with nerve growth factor, 16,16 dimethyl prostaglandin E2, and 5-aminoimidazole-4-carboxamide ribonucleotide.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.

Fatty Acid Metabolites as Novel Regulators of Non-shivering Thermogenesis

Fatty acids are essential contributors to adipocyte-based non-shivering thermogenesis by acting as activators of uncoupling protein 1 and serving as fuel for mitochondrial heat production. Novel evidence suggests a contribution to this thermogenic mechanism by their conversion to bioactive compounds. Mammalian cells produce a plethora of oxylipins and endocannabinoids, some of which have been identified to affect the abundance or thermogenic activity of brown and brite adipocytes. These effectors are produced locally or at distant sites and signal toward thermogenic adipocytes via a direct interaction with these cells or indirectly via secondary mechanisms. These interactions are evoked by the activation of receptor-mediated pathways. The endogenous production of these compounds is prone to modulation by the dietary intake of the respective precursor fatty acids. The effect of nutritional interventions on uncoupling protein 1-derived thermogenesis may thus at least in part be conferred by the production of a supportive oxylipin and endocannabinoid profile. The manipulation of this system in future studies will help to elucidate the physiological potential of these compounds as novel, endogenous regulators of non-shivering thermogenesis.