Wnt/Wingless signaling promotes lipid mobilization through signal-induced transcriptional repression.

The Wnt/Wingless signaling pathway plays critical roles in metazoan development and energy metabolism, but its role in regulating lipid homeostasis remains not fully understood. Here, we report that the activation of canonical Wnt/Wg signaling promotes lipolysis while concurrently inhibiting lipogenesis and fatty acid ß-oxidation in both larval and adult adipocytes, as well as cultured S2R+ cells, in Drosophila. Using RNA-sequencing and CUT&RUN (Cleavage Under Targets & Release Using Nuclease) assays, we identified a set of Wnt target genes responsible for intracellular lipid homeostasis. Notably, active Wnt signaling directly represses the transcription of these genes, resulting in decreased de novo lipogenesis and fatty acid ß-oxidation, but increased lipolysis. These changes lead to elevated free fatty acids and reduced triglyceride (TG) accumulation in adipocytes with active Wnt signaling. Conversely, downregulation of Wnt signaling in the fat body promotes TG accumulation in both larval and adult adipocytes. The attenuation of Wnt signaling also increases the expression of specific lipid metabolism-related genes in larval adipocytes, wing discs, and adult intestines. Taken together, these findings suggest that Wnt signaling-induced transcriptional repression plays an important role in regulating lipid homeostasis by enhancing lipolysis while simultaneously suppressing lipogenesis and fatty acid ß-oxidation.

Propranolol Alleviates Cardiac Injury After Acute Catecholamine Infusion Through p38-MAPK Pathways.

ABSTRACT: Hypercatecholaminergic conditions are known to cause heart failure and cardiac fibrosis when severe. Although previous investigations have studied the effects of beta-blockade in experimental models of catecholaminergic states, the detailed benefits of beta-blockade in more realistic models of hyper-adrenergic states were less clear. In this study, we examined acute cardiac changes in rats with hyperacute catecholamine-induced heart failure with and without propranolol treatment. Male Sprague-Dawley rats (n = 12) underwent a 6-hour infusion of epinephrine and norepinephrine alone, with an additional propranolol bolus (1 mg/kg) at hour 1 (n = 6). Cardiac tissues were examined after 6 hours. Cardiac immunohistochemistry revealed significantly decreased expression of phosphorylated p-38 (left ventricle, P = 0.021; right ventricle, P = 0.021), with upregulation of reactive oxidative species and other profibrosis proteins, after catecholamine infusion alone. After 1 propranolol 1 mg/kg bolus, the levels of phosphorylated-p38 returned to levels comparable with sham (left ventricle, P = 0.021; right ventricle, P = 0.043), with additional findings including downregulation of the apoptotic pathway and profibrotic proteins. We conclude that catecholamine-induced heart failure exerts damage through the p-38 mitogen-activated protein kinase pathway and demonstrates profibrotic changes mediated by matrix metalloproteinase 9, alpha-smooth muscle actin, and fibroblast growth factor 23. Changes in these pathways attenuated acute catecholamine-induced heart failure after propranolol bolus 1 mg/kg. We conclude that propranolol bolus at 1 mg/kg is able to mediate the effects of catecholamine excess through the p-38 mitogen-activated protein kinase pathway, profibrosis, and extrinsic apoptosis pathway.

Distinct effects of CDK8 module subunits on cellular growth and proliferation in Drosophila.

The Mediator complex, composed of about 30 conserved subunits, plays a pivotal role in facilitating RNA polymerase II-dependent transcription in eukaryotes. Within this complex, the CDK8 kinase module (CKM), comprising Med12, Med13, CDK8, and CycC (Cyclin C), serves as a dissociable subcomplex that modulates the activity of the small Mediator complex. Genetic studies in Drosophila have revealed distinct phenotypes of CDK8-CycC and Med12-Med13 mutations, yet the underlying mechanism has remained unknown. Here, using Drosophila as a model organism, we show that depleting CDK8-CycC enhances E2F1 target gene expression and promotes cell-cycle progression. Conversely, depletion of Med12-Med13 affects the expression of ribosomal protein genes and fibrillarin, indicating a more severe reduction in ribosome biogenesis and cellular growth compared to the loss of CDK8-CycC. Moreover, we found that the stability of CDK8 and CycC relies on Med12 and Med13, with a mutually interdependent relationship between Med12 and Med13. Furthermore, CycC stability depends on the other three CKM subunits. These findings reveal distinct roles for CKM subunits in vivo , with Med12-Med13 disruption exerting a more pronounced impact on ribosome biogenesis and cellular growth compared to the loss of CDK8-CycC. Significance: The CDK8 kinase module (CKM), comprising CDK8, CycC, Med12, and Med13, is essential in the Mediator complex for RNA polymerase II-dependent transcription in eukaryotes. While expected to function jointly, CKM subunit mutations result in distinct phenotypes in Drosophila . This study investigates the mechanisms driving these differing effects. Our analysis reveals the role of Med12-Med13 pair in regulating ribosomal biogenesis and cellular growth, contrasting with the involvement of CDK8-CycC in E2F1-dependent cell-cycle progression. Additionally, an asymmetric interdependence in the stability of CDK8-CycC and Med12-Med13 was observed. CKM mutations or overexpression are associated with cancers and cardiovascular diseases. Our findings underscore the distinct impacts of CKM mutations on cellular growth and proliferation, advancing our understanding of their diverse consequences in vivo .

Cdk8 attenuates lipogenesis by inhibiting SREBP-dependent transcription in Drosophila.

Fine-tuning of lipogenic gene expression is important for the maintenance of long-term homeostasis of intracellular lipids. The SREBP family of transcription factors are master regulators that control the transcription of lipogenic and cholesterogenic genes, but the mechanisms modulating SREBP-dependent transcription are still not fully understood. We previously reported that CDK8, a subunit of the transcription co-factor Mediator complex, phosphorylates SREBP at a conserved threonine residue. Here, using Drosophila as a model system, we observed that the phosphodeficient SREBP proteins (SREBP-Thr390Ala) were more stable and more potent in stimulating the expression of lipogenic genes and promoting lipogenesis in vivo than wild-type SREBP. In addition, starvation blocked the effects of wild-type SREBP-induced lipogenic gene transcription, whereas phosphodeficient SREBP was resistant to this effect. Furthermore, our biochemical analyses identified six highly conserved amino acid residues in the N-terminus disordered region of SREBP that are required for its interactions with both Cdk8 and the MED15 subunit of the small Mediator complex. These results support that the concerted actions of Cdk8 and MED15 are essential for the tight regulation of SREBP-dependent transcription. This article has an associated First Person interview with the first author of the paper.

Convergent charge interval spacing of zwitterionic 4-vinylpyridine carboxybetaine structures for superior blood-inert regulation in amphiphilic phases.

Antifouling materials are indispensable in the biomedical field, but their high hydrophilicity and surface free energy provoke contamination on surfaces under atmospheric conditions, thus limiting their applicability in medical devices. This study proposes a new zwitterionic structure, 4-vinylpyridine carboxybetaine (4VPCB), that results in lower surface free energy and increases biological inertness. In the design of 4VPCB, one to three carbon atoms are inserted between the positive charge and negative charge (carbon space length, CSL) of the pyridyl-containing side chain to adjust hydration with water molecules. The pyridine in the 4VPCB structure provides the hydrophobicity of the zwitterionic functional group, and thus it can have a lower free energy in the gas phase but maintain higher hydrophilicity in the liquid phase environment. Surface plasmon resonance and confocal microscopy were used to analyze the antiprotein adsorption and anti-blood cell adhesion properties of the P4VPCB brush surface. The results showed that the CSL in the P4VPCB structure affected the biological inertness of the surface. The protein adsorption on the surface of P4VPCB2 (CSL= 2) is lower than that on the surfaces of P4VPCB1 (CSL = 1) and P4VPCB3 (CSL = 3), and the optimal resistance to protein adsorption can be reduced to 7.5 ng cm-2. The surface of P4VPCB2 can also exhibit excellent blood-inert function in the adhesion test with various human blood cells, offering a potential possibility for the future design of a new generation of blood-inert medical materials.

Rectovaginal Colonization With Pathogenic Escherichia coli During Pregnancy And Neonatal Outcomes.

PURPOSE: The role of pathogenic Escherichia coli colonization in asymptomatic pregnant women is not well understood. The purpose of this work was to determine the prevalence, antimicrobial susceptibility, and neonatal outcomes of pathogenic E. coli colonization in pregnant women. PATIENTS AND METHODS: A total of 137 women from southern Taiwan with singleton pregnancies were enrolled between March 2016 and June 2017. The women were prospectively screened for E. coli colonization in the rectovaginal region during prenatal examination. The exclusion criteria are twin pregnancy of the mother and major anomaly of the neonate. All E. coli isolates were identified as either pathogenic or commensal strains, and their susceptibility to various antimicrobials was investigated. Clinical data of the infants were retrieved from their medical records. RESULTS: Results showed that 35.8% of asymptomatic pregnant women had pathogenic E. coli colonization in the rectovaginal region. Neonates born to such mothers showed significant morbidities, including hospitalization (OR= 3.74, 95% CI= 1.18~11.87), hyperbilirubinemia (OR= 2.81, 95% CI= 1.24~6.38), and gastrointestinal symptoms (OR= 5.53, 95% CI= 1.39~21.94). Maternal colonization with pathogenic E. coli at rectoanal site was a risk factor for neonatal hyperbilirubinemia after Benjamini-Hochberg (BH) adjustment (52% vs 24%, adjusted P= 0.048). CONCLUSION: The prevalence of pathogenic E. coli colonization in Taiwanese asymptomatic pregnant women was high, and the neonates born to colonized mothers exhibited potential neonatal morbidities. Larger studies are necessary to confirm these findings.

Antioxidant and antiglycation properties of different solvent extracts from Chinese olive (Canarium album L.) fruit.

OBJECTIVE: To evaluate the antioxidant activity, antiglycation property, and bioactive components content of different solvent extracts from Chinese olive (Canarium album L.) fruit. METHODS: The dry powder of Chinese olive fruit was extracted with different solvents, i.e., water, water/ethanol (1/1, v/v), ethanol, methanol, acetone and ethyl acetate. The total phenolic, total flavonoids and total triterpenoids contents of various extracts were determined by spectrophotometric methods. Phenolic compounds were identified by high performance liquid chromatography. The assayed antioxidant activity was determined in vitro models such as antioxidant capacity by radical scavenging activity using 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picryl- hydrazyl (DPPH) and nitrite oxide methods, chelating activity on metal ions, lipid and protein peroxidation methods. In vitro glucose-bovine serum albumin assay was used to evaluate the antiglycation of various extracts. RESULTS: The water/ethanol extracts of Chinese olive fruit exerted significant scavenging effects on free radicals and strong inhibitory effects on advanced glycation end products formation. The Chinese olive fruit extracts were rich in phenolic compounds and triterpenoids. Gallic acid, ferulic acid and rutin were identified from the water/ethanol extracts. Correlation analysis indicated that there was a linear relationship between the antioxidant potency, free radical scavenging ability and phenolic compounds content of the Chinese olive fruit extracts. CONCLUSIONS: Chinese olive fruit could be a natural candidate for studies of dietary complement to diabetes treatment since it combines antioxidant and antiglycation activities.