Vps15 is critical to mediate autophagy in AngII treated HUVECs probably by PDK1/PKC signaling pathway

SCFFBXW5-mediated degradation of AQP3 suppresses autophagic cell death through the PDPK1-AKT-MTOR axis in hepatocellular carcinoma cells

AQP3 (aquaporin 3 (Gill blood group)), a member of the AQP family, is an aquaglyceroporin which transports water, glycerol and small solutes across the plasma membrane. Beyond its role in fluid transport, AQP3 plays a significant role in regulating various aspects of tumor cell behavior, including cell proliferation, migration, and invasion. Nevertheless, the underlying regulatory mechanism of AQP3 in tumors remains unclear. Here, for the first time, we report that AQP3 is a direct target for ubiquitination by the SCFFBXW5 complex. In addition, we revealed that downregulation of FBXW5 significantly induced AQP3 expression to prompt macroautophagic/autophagic cell death in hepatocellular carcinoma (HCC) cells. Mechanistically, AQP3 accumulation induced by FBXW5 knockdown led to the degradation of PDPK1/PDK1 in a lysosomal-dependent manner, thus inactivating the AKT-MTOR pathway and inducing autophagic death in HCC. Taken together, our findings revealed a previously undiscovered regulatory mechanism through which FBXW5 degraded AQP3 to suppress autophagic cell death via the PDPK1-AKT-MTOR axis in HCC cells.Abbreviation: BafA1: bafilomycin A1; CQ: chloroquine; CRL: CUL-Ring E3 ubiquitin ligases; FBXW5: F-box and WD repeat domain containing 5; HCC: hepatocellular carcinoma; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; 3-MA: 3-methyladenine; PDPK1/PDK1: 3-phosphoinositide dependent protein kinase 1; RBX1/ROC1: ring-box 1; SKP1: S-phase kinase associated protein 1; SCF: SKP1-CUL1-F-box protein.

Salt-contaminated water inducing pulmonary hypertension and kidney damage by increasing Ang II concentration in broilers

NaCl is the main component of freshwater salinization. High NaCl concentration in drinking water can cause pulmonary hypertension syndrome (PHS) and kidney damage in broilers. To explore the effect of NaCl in drinking water on broilers' kidneys, this study divided 80 chickens into four groups. With the control group fed with pure water, broiler chickens were fed with fresh water (FW, NaCl 1 g/L), low salt-contaminated water (L-SCW, NaCl 2.5 g/L), and high salt-contaminated water (H-SCW, NaCl 5 g/L). The results show that ascites heart index (AHI) and hematocrit (HCT) of broilers increase in L-SCW and H-SCW, the serum blood urea nitrogen and creatinine of broilers increase significantly, the kidney index increases, the kidney sections show vacuolar degeneration and fibrotic degeneration, and the TUNEL results show that the kidneys possess obvious apoptosis. In addition, the detection of RAAS-related genes (AGT gene in the liver, REN in the kidney, ACE in the lung) demonstrates that after using salt-contaminated water, the transcription levels of AGT, REN, and ACE rise significantly, and the concentration of angiotensin II (Ang II) also increases significantly. In order to verify the effect of Ang II on broiler kidneys, this research used exogenous Ang II to treat chicken embryonic kidney (CEK) cells. The results show that the cell activity of CEK decreased with the increase of the concentration of exogenous Ang II. Meanwhile, the flow cytometry assay shows that Ang II could promote the apoptosis of CEK cells. These results indicate that the salt-contaminated water can aggravate PHS and cause kidney damage. The mechanism may be related to the increase of Ang II.

The Role of Phosphatidylinositol 3-Kinase Catalytic Subunit Type 3 in the Pathogenesis of Human Cancer

Phosphatidylinositol 3-kinase catalytic subunit type 3 (PIK3C3), the mammalian ortholog of yeast vesicular protein sorting 34 (Vps34), belongs to the phosphoinositide 3-kinase (PI3K) family. PIK3C3 can phosphorylate phosphatidylinositol (PtdIns) to generate phosphatidylinositol 3-phosphate (PI3P), a phospholipid central to autophagy. Inhibition of PIK3C3 successfully inhibits autophagy. Autophagy maintains cell survival when modifications occur in the cellular environment and helps tumor cells resist metabolic stress and cancer treatment. In addition, PIK3C3 could induce oncogenic transformation and enhance tumor cell proliferation, growth, and invasion through mechanisms independent of autophagy. This review addresses the structural and functional features, tissue distribution, and expression pattern of PIK3C3 in a variety of human tumors and highlights the underlying mechanisms involved in carcinogenesis. The implications in cancer biology, patient prognosis prediction, and cancer therapy are discussed. Altogether, the discovery of pharmacological inhibitors of PIK3C3 could reveal novel strategies for improving treatment outcomes for PIK3C3-mediated human diseases.

Scutellarin ameliorates high glucose-induced vascular endothelial cells injury by activating PINK1/Parkin-mediated mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellarin (Scu) is one of the main active ingredients of Erigeron breviscapus (Vant.) Hand.-Mazz which has been used to treat cardiovascular disease including vascular dysfunction caused by diabetes. Scu also has a protective effect on vascular endothelial cells against hyperglycemia. However, molecular mechanisms underlying this effect are not clear.

AIM OF THE STUDY

This aim of this study was to investigate the effect of Scu on human umbilical vein endothelial cells (HUVECs) injury induced by high glucose (HG), especially the regulation of PTEN-induced kinase 1 (PINK1)/Parkin-mediated mitophagy.

MATERIALS AND METHODS

HUVECs were exposed to HG to induce vascular endothelial cells injury in vitro. Cell viability was assessed by MTT assay. The extent of cell apoptosis was measured by Hoechst staining and flow cytometry. Mitophagy was assayed by fluorescent immunostaining, transmission electron microscope and immunoblot. Besides, virtual docking was conducted to validate the interaction of PINK1 protein and Scu.

RESULTS

We found that Scu significantly increased cell viability in HG-treated HUVECs. Scu reduces the expression of Bcl-2, Bax and cytochrome C (Cyt.c) to inhibit apoptosis through a mitochondria-dependent pathway. Meanwhile, Scu improved the overload of reactive oxygen species (ROS), superoxide dismutase (SOD) activity and SOD2 protein expression, and reversed the collapse of mitochondrial membrane potential. Besides, Scu increased autophagic flux, improved the expression of microtubule-associated protein 1 light chain 3 Ⅱ (LC3 II), Beclin 1 and autophagy-related gene 5 (Atg 5) and decreased the expression of Sequestosome1/P62 in HG-treated HUVECs. Furthermore, Scu improved the expressions of PINK1, Parkin, and Mitofusin2, which revealed the enhancement of mitophagy. Moreover, the beneficial effects of Scu on HG-induced low expression of Parkin, overproduction of ROS, and over expressions of P62, Cyt.c and Cleaved caspase-3 were weakened by PINK1 gene knockdown. Molecular docking suggested good interaction of Scu and PINK1 protein.

CONCLUSION

These results suggest that Scu may protect vascular endothelial cells against hyperglycemia-induced injury by up-regulating mitophagy via PINK1/Parkin signal pathway.

Oxidative Stress Triggers Defective Autophagy in Endothelial Cells: Role in Atherothrombosis Development

Atherothrombosis, a multifactorial and multistep artery disorder, represents one of the main causes of morbidity and mortality worldwide. The development and progression of atherothrombosis is closely associated with age, gender and a complex relationship between unhealthy lifestyle habits and several genetic risk factors. The imbalance between oxidative stress and antioxidant defenses is the main biological event leading to the development of a pro-oxidant phenotype, triggering cellular and molecular mechanisms associated with the atherothrombotic process. The pathogenesis of atherosclerosis and its late thrombotic complications involve multiple cellular events such as inflammation, endothelial dysfunction, proliferation of vascular smooth muscle cells (SMCs), extracellular matrix (ECM) alterations, and platelet activation, contributing to chronic pathological remodeling of the vascular wall, atheromatous plague formation, vascular stenosis, and eventually, thrombus growth and propagation. Emerging studies suggest that clotting activation and endothelial cell (EC) dysfunction play key roles in the pathogenesis of atherothrombosis. Furthermore, a growing body of evidence indicates that defective autophagy is closely linked to the overproduction of reactive oxygen species (ROS) which, in turn, are involved in the development and progression of atherosclerotic disease. This topic represents a large field of study aimed at identifying new potential therapeutic targets. In this review, we focus on the major role played by the autophagic pathway induced by oxidative stress in the modulation of EC dysfunction as a background to understand its potential role in the development of atherothrombosis.

Syndecan 4 contributes to osteoclast differentiation induced by RANKL through enhancing autophagy

Periodontitis is a common chronic disease. Osteoclast differentiation contributes to alveolar bone resorption which is a distinct phenomenon during periodontitis. Syndecan 4 (SDC4), a member of the syndecan family, was found to be highly expressed during periodontitis. However, little is known about its role in periodontitis. Herein, we explored the role of SDC4 in osteoclast differentiation. An experimental periodontitis rat model was established by ligating the right first molar. The SDC4 expression in periodontium was detected by western blot and immunofluorescence. Our study demonstrated that SDC4 was highly expressed in the periodontium of periodontitis rats. It was positively transcriptionally regulated by NF-κB. SDC4 silencing abrogated osteoclast differentiation induced by RANKL, while SDC4 overexpression enhanced osteoclast differentiation. Moreover, SDC4 enhanced autophagy induced by RANKL. 3-MA, an autophagy inhibitor, was employed to explore whether SDC4 impacts osteoclast differentiation through activating autophagy. Treatment with 3-MA abolished osteoclast differentiation which was enhanced by SDC4, indicating that SDC4 promotes osteoclast differentiation through activating autophagy. This study reveals that SDC4 may contribute to osteoclast differentiation during periodontitis through activating autophagy. It sheds light on the important role of SDC4 in periodontitis.

Paeonol inhibits apoptosis of vascular smooth muscle cells via up-regulation of autophagy by activating class III PI3K/Beclin-1 signaling pathway

AIMS

The cross talk between autophagy and apoptosis of vascular smooth muscle cells (VSMCs) plays a vital role in the development of atherosclerosis (AS). Paeonol is isolated from the radix of Cortex Moutan with anti-atherosclerotic and anti-apoptosis effects. However, the mechanisms of paeonol on VSMCs apoptosis are still not fully understood. In this study, we aimed to explore whether paeonol could inhibit VSMCs apoptosis though modulating VSMCs autophagy.

MATERIALS AND METHODS

The proteins expressions were detected by western blotting. Autophagosomes and apoptoticbody formation in VSMCs was observed by transmission electron microscopy (TEM). VSMCs autophagy was detected by monodansylcadaverine (MDC) staining using fluorescence microscopy, while VSMCs apoptosis was determined by 4',6-diamidino-2-phenylindole (DAPI) and flow cytometry.

KEY FINDINGS

We found that paeonol could significantly increase LC3II protein level, decrease p62 and cleaved caspase-3 proteins levels in aorta of AS mice and ox-LDL-injured VSMCs. Paeonol could augment the number of autophagosomes and reduce the amount of apoptotic bodies in ox-LDL-injured VSMCs. Moreover, paeonol obviously induced VSMCs autophagy compared to ox-LDL group and remarkably suppressed VSMCs apoptosis. However, the effects of paeonol on VSMCs apoptosis could be reversed obviously by 3-MA, the autophagy inhibitor. Furthermore, paeonol could activate class III PI3K-Beclin-1 pathway significantly. Gene silencing of either class III PI3K or Beclin-1 could reverse the effects of paeonol on VSMCs autophagy and apoptosis.

SIGNIFICANCE

Based on our results, paeonol could induce VSMCs autophagy by activating class III PI3K/Beclin-1 signaling pathway, thus ultimately inhibiting VSMCs apoptosis.