Neuregulin-4 protects cardiomyocytes against high-glucose-induced ferroptosis via the AMPK/NRF2 signalling pathway.

BACKGROUND: High glucose levels are key factors and key contributors to several cardiovascular diseases associated with cardiomyocyte injury. Ferroptosis, which was identified in recent years, is a mode of cell death caused by the iron-mediated accumulation of lipid peroxides. Neuregulin-4 (Nrg4) is an adipokine that has protective effects against metabolic disorders and insulin resistance. Our previous study revealed that Nrg4 has a protective effect against diabetic myocardial injury, and the aim of this study was to investigate whether Nrg4 could attenuate the occurrence of high glucose-induced ferroptosis in cardiomyocytes. METHODS: We constructed an in vivo diabetic myocardial injury model in which primary cardiomyocytes were cultured in vitro and treated with Nrg4. Changes in ferroptosis-related protein levels and ferroptosis-related indices in cardiomyocytes were observed. In addition, we performed back-validation and explored signalling pathways that regulate ferroptosis in primary cardiomyocytes. RESULTS: Nrg4 attenuated cardiomyocyte ferroptosis both in vivo and in vitro. Additionally, the AMPK/NRF2 signalling pathway was activated during this process, and when the AMPK/NRF2 pathway was inhibited, the beneficial effects of Nrg4 were attenuated. CONCLUSION: Nrg4 antagonizes high glucose-induced ferroptosis in cardiomyocytes via the AMPK/NRF2 signalling pathway.

An EMC-Hpo-Yki axis maintains intestinal homeostasis under physiological and pathological conditions.

Balanced control of stem cell proliferation and differentiation underlines tissue homeostasis. Disruption of tissue homeostasis often results in many diseases. However, how endogenous factors influence the proliferation and differentiation of intestinal stem cells (ISCs) under physiological and pathological conditions remains poorly understood. Here, we find that the evolutionarily conserved endoplasmic reticulum membrane protein complex (EMC) negatively regulates ISC proliferation and intestinal homeostasis. Compromising EMC function in progenitors leads to excessive ISC proliferation and intestinal homeostasis disruption. Mechanistically, the EMC associates with and stabilizes Hippo (Hpo) protein, the key component of the Hpo signaling pathway. In the absence of EMC, Yorkie (Yki) is activated to promote ISC proliferation due to Hpo destruction. The EMC-Hpo-Yki axis also functions in enterocytes to maintain intestinal homeostasis. Importantly, the levels of the EMC are dramatically diminished in tunicamycin-treated animals, leading to Hpo destruction, thereby resulting in intestinal homeostasis disruption due to Yki activation. Thus, our study uncovers the molecular mechanism underlying the action of the EMC in intestinal homeostasis maintenance under physiological and pathological conditions and provides new insight into the pathogenesis of tunicamycin-induced tumorigenesis.

A feedforward loop between JAK/STAT downstream target p115 and STAT in germline stem cells.

The maintenance of germline stem cells (GSCs) is essential for tissue homeostasis. JAK/STAT signaling maintains GSC fate in Drosophila testis. However, how JAK/STAT signaling maintains male GSC fate through its downstream targets remains poorly understood. Here, we identify p115, a tER/cis-Golgi golgin protein, as a putative downstream target of JAK/STAT signaling. p115 maintains GSC fate independent of GM130 and GRASP65. p115 localizes in cytosol, the ER and Golgi apparatus in germline cells and is required for the morphology of the ER and Golgi apparatus. Furthermore, depletion of p115 in GSCs results in aberrant spindle orientation. Mechanistically, p115 associates with and stabilizes STAT. Finally, ectopic expression of STAT completely restores GSC loss caused by p115 depletion. Collectively, JAK/STAT signaling and p115 form a feedforward loop to maintain male GSC fate. Our work provides new insights into the regulatory mechanism of how stem cell maintenance is properly controlled by JAK/STAT signaling.

Speckle-tracking echocardiography provides sensitive measurements of subtle early alterations associated with cardiac dysfunction in T2DM rats.

BACKGROUND: Diabetic cardiomyopathy results in cardiac structural and functional abnormalities. Previous studies have demonstrated that inhibiting the RhoA/ROCK signalling pathway increases the injury resistance of cardiomyocytes. The early detection of cardiac structural and functional alterations may facilitate an improved understanding of the pathophysiologic progress and guide therapy. This study aimed to identify the optimal diagnostic measures for the subtle early alterations of cardiac dysfunction in type 2 diabetes mellitus (T2DM) rats. METHODS: Twenty-four rat models were divided into four groups and received treatments for 4 weeks: the CON group (control rats), the DM group (T2DM rats), the DMF group (T2DM rats receiving fasudil) and the CONF group (control rats receiving fasudil) group. Left ventricular (LV) structure was quantified by histological staining and transmission electron microscopy. LV function and myocardial deformation were assessed by high-frequency echocardiography. RESULTS: Treatment with fasudil, a ROCK inhibitor, significantly protected against diabetes-induced myocardial hypertrophy, fibrosis and mitochondrial dysfunction. Impaired LV performance was found in T2DM rats, as evidenced by significant reductions in the ejection fraction (EF), fractional shortening (FS) and the mitral valve (MV) E/A ratio (which decreased 26%, 34% and 20%, respectively). Fasudil failed to improve the conventional ultrasonic parameters in T2DM rats, but the myocardial deformation measured by speckle-tracking echocardiography (STE) were significantly improved (global circumferential strain, GCS: P = 0.003; GCS rate, GCSR: P = 0.021). When receiver operating characteristic (ROC) curves were used in combination with linear regression analysis, STE parameters were found to be characterized by both optimal prediction of cardiac damage [AUC (95% CI): fractional area change, FAC: 0.927 (0.744, 0.993); GCS: 0.819 (0.610, 0.945); GCSR: 0.899 (0.707, 0.984)] and stronger correlations with cardiac fibrosis (FAC: r = -0.825; GCS: r = 0.772; GCSR: r = 0.829) than conventional parameters. CONCLUSION: The results suggest that STE parameters are more sensitive and specific than conventional parameters in predicting the subtle cardiac functional changes that occur in the early stage, providing new insight into the management of diabetic cardiomyopathy.

The Yun/Prohibitin complex regulates adult Drosophila intestinal stem cell proliferation through the transcription factor E2F1.

Stem cells constantly divide and differentiate to maintain adult tissue homeostasis, and uncontrolled stem cell proliferation leads to severe diseases such as cancer. How stem cell proliferation is precisely controlled remains poorly understood. Here, from an RNA interference (RNAi) screen in adult Drosophila intestinal stem cells (ISCs), we identify a factor, Yun, required for proliferation of normal and transformed ISCs. Yun is mainly expressed in progenitors; our genetic and biochemical evidence suggest that it acts as a scaffold to stabilize the Prohibitin (PHB) complex previously implicated in various cellular and developmental processes and diseases. We demonstrate that the Yun/PHB complex is regulated by and acts downstream of EGFR/MAPK signaling. Importantly, the Yun/PHB complex interacts with and positively affects the levels of the transcription factor E2F1 to regulate ISC proliferation. In addition, we find that the role of the PHB complex in cell proliferation is evolutionarily conserved. Thus, our study uncovers a Yun/PHB-E2F1 regulatory axis in stem cell proliferation.

[Design and verification of microelectrode twisting machine].

As an interface between external electronic devices and internal neural nuclei, microelectrodes play an important role in many fields, such as animal robots, deep brain stimulation and neural prostheses. Aiming at the problem of high price and complicated fabrication process of microelectrode, a microelectrode twisting machine based on open source electronic prototyping platform (Arduino) and three-dimensional printing technology was proposed, and its microelectrode fabrication performance and neural stimulation performance were verified. The results show that during the fabrication of microelectrodes, the number of positive twisting turns of the electrode wire should generally be set to about 1.8 times of its length, and the number of reverse twisting rings is independent of the length, generally about 5. Moreover, compared with the traditional instrument, the device is not only inexpensive and simple to manufacture, but also has good expandability. It has a positive significance for both the personalization and popularization of microelectrode fabrication and the reduction of experimental cost.

Wildtype adult stem cells, unlike tumor cells, are resistant to cellular damages in Drosophila.

Adult stem cells or residential progenitor cells are critical to maintain the structure and function of adult tissues (homeostasis) throughout the lifetime of an individual. Mis-regulation of stem cell proliferation and differentiation often leads to diseases including cancer, however, how wildtype adult stem cells and cancer cells respond to cellular damages remains unclear. We find that in the adult Drosophila midgut, intestinal stem cells (ISCs), unlike tumor intestinal cells, are resistant to various cellular damages. Tumor intestinal cells, unlike wildtype ISCs, are easily eliminated by apoptosis. Further, their proliferation is inhibited upon autophagy induction, and autophagy-mediated tumor inhibition is independent of caspase-dependent apoptosis. Interestingly, inhibition of tumorigenesis by autophagy is likely through the sequestration and degradation of mitochondria, as compromising mitochondria activity in these tumor models mimics the induction of autophagy and increasing the production of mitochondria alleviates the tumor-suppression capacity of autophagy. Together, these data demonstrate that wildtype adult stem cells and tumor cells show dramatic differences in sensitivity to cellular damages, thus providing potential therapeutic implications targeting tumorigenesis.

Remnant-like lipoproteins may accelerate endothelial progenitor cells senescence through inhibiting telomerase activity via the reactive oxygen species-dependent pathway.

BACKGROUND: We previously found that remnant-like lipoproteins (RLPs), lipolytic products of triglyceride-rich lipoproteins including very low-density lipoprotein and chylomicron, can accelerate endothelial progenitor cell (EPC) senescence, which involves telomerase activity. The aim of this study was to investigate the effects of RLPs on telomerase activity and the catalytic subunit telomerase reverse transcriptase (TERT) in EPCs and the associated signal pathway. METHODS: RLPs were prepared from plasma samples by the immunoaffinity method. EPCs at day 8 were incubated with RLPs at 10-, 50-, 100-, and 200-µg/mL for 24 hours. Telomerase activity was measured with telomeric repeat amplification protocol assay, and optimum concentration of RLPs was determined. Human TERT (hTERT) and phosphorylated Akt protein kinase were detected by Western blot analysis in RLP-incubated EPCs with or without pretreatment of either superoxide dismutase or atorvastatin for 3 hours. Phosphorylated hTERT was measured by immunoprecipitation and Western blot assay. Nitrotyrosine was evaluated by immunofluorescence assay, and senescent EPCs were determined by senescence-associated ß-galactosidase staining. RESULTS: Dose dependently, RLPs resulted in a decrease in telomerase activity, with a maximal effect at 200 µg protein/mL. The optimum concentration of RLPs was determined as 100 µg protein/mL. This dosage resulted in significant increases in senescence-associated ß-galactosidase-positive cell and nitrotyrosine staining. In addition, RLPs decreased the expression of hTERT and repressed the phosphorylation of Akt and hTERT. Pretreatment of either superoxide dismutase or atorvastatin remarkably reversed these effects. CONCLUSIONS: RLPs may suppress telomerase activity and accelerate EPC senescence through downregulating hTERT expression via the reactive oxygen species-dependent pathway.

[Optimization of extraction conditions for semi-bionic extraction of Guizhi Fuling pill decoction by uniform design].

OBJECTIVE: To optimize the extraction conditions for semi-bionic extraction of Guizhi Fuling pill decoction. METHOD: The best extraction condition of the semi-bionic extraction for Guizhi Fuling pill decoction was optimized by uniform design was optimized with paeoniflorin, cinnamic acid, laetrile, pachymic acid, total polysaccharose and dry extract as the indexes. RESULT: The optimized extraction condition is that extracting for 3 times with solvent pH values of 4.98, 7.35 and 8.00, respectively, and the total extracting time was 4.99 h. CONCLUSION: In consideration of manufacturing fact, the pH value of thrice extractions is set at 5.0, 7.5, 8.0 respectively, and the extracting time is 2.0, 1.5, 1.5 h in turn.