HIF-1α Ameliorates Diabetic Neuropathic Pain via Parkin-Mediated Mitophagy in a Mouse Model

Interplay between hypoxia inducible Factor-1 and mitochondria in cardiac diseases

Ischemic heart diseases and cardiomyopathies are characterized by hypoxia, energy starvation and mitochondrial dysfunction. HIF-1 acts as a cellular oxygen sensor, tuning the balance of metabolic and oxidative stress pathways to provide ATP and sustain cell survival. Acting on mitochondria, HIF-1 regulates different processes such as energy substrate utilization, oxidative phosphorylation and mitochondrial dynamics. In turn, mitochondrial homeostasis modifications impact HIF-1 activity. This underlies that HIF-1 and mitochondria are tightly interconnected to maintain cell homeostasis. Despite many evidences linking HIF-1 and mitochondria, the mechanistic insights are far from being understood, particularly in the context of cardiac diseases. Here, we explore the current understanding of how HIF-1, reactive oxygen species and cell metabolism are interconnected, with a specific focus on mitochondrial function and dynamics. We also discuss the divergent roles of HIF in acute and chronic cardiac diseases in order to highlight that HIF-1, mitochondria and oxidative stress interaction deserves to be deeply investigated. While the strategies aiming at stabilizing HIF-1 have provided beneficial effects in acute ischemic injury, some deleterious effects were observed during prolonged HIF-1 activation. Thus, deciphering the link between HIF-1 and mitochondria will help to optimize HIF-1 modulation and provide new therapeutic perspectives for the treatment of cardiovascular pathologies.

Heyingwuzi formulation alleviates diabetic retinopathy by promoting mitophagy via the HIF-1α/BNIP3/NIX axis

BACKGROUND

Diabetic retinopathy (DR) is the primary cause of visual problems in patients with diabetes. The Heyingwuzi formulation (HYWZF) is effective against DR.

AIM

To determine the HYWZF prevention mechanisms, especially those underlying mitophagy.

METHODS

Human retinal capillary endothelial cells (HRCECs) were treated with high glucose (hg), HYWZF serum, PX-478, or Mdivi-1 in vitro. Then, cell counting kit-8, transwell, and tube formation assays were used to evaluate HRCEC proliferation, invasion, and tube formation, respectively. Transmission electron microscopy was used to assess mitochondrial morphology, and Western blotting was used to determine the protein levels. Flow cytometry was used to assess cell apoptosis, reactive oxygen species (ROS) production, and mitochondrial membrane potential. Moreover, C57BL/6 mice were established in vivo using streptozotocin and treated with HYWZF for four weeks. Blood glucose levels and body weight were monitored continuously. Changes in retinal characteristics were evaluated using hematoxylin and eosin, tar violet, and periodic acid-Schiff staining. Protein levels in retinal tissues were determined via Western blotting, immunohistochemistry, and immunostaining.

RESULTS

HYWZF inhibited excessive ROS production, apoptosis, tube formation, and invasion in hg-induced HRCECs via mitochondrial autophagy in vitro. It increased the mRNA expression levels of BCL2-interacting protein 3 (BNIP3), FUN14 domain-containing 1, BNIP3-like (BNIP3L, also known as NIX), PARKIN, PTEN-induced kinase 1, and hypoxia-inducible factor (HIF)-1α. Moreover, it downregulated the protein levels of vascular endothelial cell growth factor and increased the light chain 3-II/I ratio. However, PX-478 and Mdivi-1 reversed these effects. Additionally, PX-478 and Mdivi-1 rescued the effects of HYWZF by decreasing oxidative stress and apoptosis and increasing mitophagy. HYWZF intervention improved the symptoms of diabetes, tissue damage, number of acellular capillaries, and oxidative stress in vivo. Furthermore, in vivo experiments confirmed the results of in vitro experiments.

CONCLUSION

HYWZF alleviated DR and associated damage by promoting mitophagy via the HIF-1α/BNIP3/NIX axis.

Network analysis to explore the anti-senescence mechanism of Jinchan Yishen Tongluo Formula (JCYSTLF) in diabetic kidneys

Background

The Jinchan Yishen Tongluo Formula (JCYSTLF) has the effect of delaying senescence in diabetic kidneys. However, the mechanism is not clear.

Purpose

Combination methods to investigate the anti-senescence mechanism of JCYSTLF in diabetic kidneys.

Methods

The main compounds of JCYSTLF were characterized by LC-MS/MS, and the anti-senescence targets of JCYSTLF were screened via network analysis. Then, we performed in vivo and in vitro experiments to validate the results.

Results

The target profiles of compounds were obtained by LC-MS/MS to characterize the primary function of JCYSTLF. Senescence was identified as a key biological functional module of JCYSTLF in the treatment of DN via constructing compounds-target-biological network analysis. Further analysis of senescence-related targets recognized the HIF-1α/autophagy pathway as the core anti-senescence mechanism of JCYSTLF in diabetic kidneys. Animal experiments showed, in comparison with valsartan, JCYSTLF showed an improvement in urinary albumin and renal pathological damage. JCYSTLF enhanced the ability of diabetic kidneys to clear senescence-related proteins via regulating autophagy confirmed by autophagy inhibitor CQ. However, HIF-1α inhibitor 2-ME weakened the role of JCYSLTF in regulating autophagy in diabetic kidneys. Meanwhile, over-expressed HIF-1α in HK-2 cells decreased the levels of SA-β-gal, p21 and p53 induced by AGEs. Upregulated HIF-1α could reverse the blocking of autophagy induced by AGEs in HK-2 cells evaluated by ptfLC3.

Conclusion

We provided in vitro and in vivo evidence for the anti-senescence role of JCYSTLF in regulating the HIF-1α/autophagy pathway.

SIRT3 alleviates painful diabetic neuropathy by mediating the FoxO3a-PINK1-Parkin signaling pathway to activate mitophagy

INTRODUCTION

Painful diabetic neuropathy (PDN) is a common complication of diabetes. Previous studies have implicated that mitochondrial dysfunction plays a role in the development of PDN, but its pathogenesis and mechanism have not been fully investigated.

METHODS

In this study, we used high-fat diet/low-dose streptozotocin-induced rats as a model of type 2 diabetes mellitus. Behavioral testing, whole-cell patch-clamp recordings of dorsal root ganglion (DRG) neurons, and complex sensory nerve conduction velocity studies were used to assess peripheral neuropathy. Mitochondrial membrane potential (MMP), ATP, tissue reactive oxygen species, and transmission electron microscopy were used to evaluate the function and morphology of mitochondria in DRG. Real-time PCR, western blot, and immunofluorescence were performed to investigate the mechanism.

RESULTS

We found that damaged mitochondria were accumulated and mitophagy was inhibited in PDN rats. The expression of sirtuin 3 (SIRT3), which is an NAD+-dependent deacetylase in mitochondria, was inhibited. Overexpression of SIRT3 in DRG neurons by intrathecally administered LV-SIRT3 lentivirus ameliorated neurological and mitochondrial dysfunctions. This was evidenced by the reversal of allodynia and nociceptor hyperexcitability, as well as the restoration of MMP and ATP levels. Overexpression of SIRT3 restored the inhibited mitophagy by activating the FoxO3a-PINK1-Parkin signaling pathway. The effects of SIRT3 overexpression, including the reversal of allodynia and nociceptor hyperexcitability, the improvement of impaired mitochondria and mitophagy, and the restoration of PINK1 and Parkin expression, were counteracted when FoxO3a siRNA was intrathecally injected.

CONCLUSION

These results showed that SIRT3 overexpression ameliorates PDN via activation of FoxO3a-PINK1-Parkin-mediated mitophagy, suggesting that SIRT3 may become an encouraging therapeutic strategy for PDN.

Silencing of FUN14 Domain Containing 1 Inhibits Platelet Activation in Diabetes Mellitus through Blocking Mitophagy

Platelet hyperactivity represents a deleterious physiological phenomenon in diabetes mellitus (DM). This study aimed to explore the role of FUN14 domain containing 1 (FUNDC1) in platelet activation within the context of DM and to uncover relevant mechanisms, with a focus on mitophagy. A mouse model of DM was established by high-fat feeding and streptozotocin injection. Platelets isolated from whole blood were exposed to carbonyl cyanide-4-(trifluo-romethoxy)phenylhydrazone (FCCP) to induce mitophagy. The relative mRNA expression of FUNDC1 was detected by quantitative real-time PCR (qRT-PCR). Western blotting was employed to measure the protein levels of FUNDC1, the ratio of LC3-II toLC3-I, and cleaved caspase-3. Immunofluorescence and flow cytometry were performed to assess LC3-positive mitochondria and platelet activation factor CD62P, respectively. Additionally, serum levels of β-thrombo-globulin (β-TG) and platelet factor 4 (PF4)were measured by enzyme-linked immunosorbent assay. FUNDC1 expression was elevated in DM mice, and its silencing decreased the body weight and fasting blood glucose. Inhibition of FUNDC1 also significantly attenuated FCCP-induced platelet mitophagy, as evidenced by the down-regulation of the LC3-II/LC3-I ratio, up-regulation of Tomm20, and diminished presence of LC3-positive mitochondria. Moreover, platelet activation was noted in DM mice; this activation was mitigated upon FUNDC1 silencing, which was confirmed by the down-regulation of cleaved caspase-3 and CD62P as well as reductions in β-TG and PF4 serum levels. Silencing of FUNDC1 inhibited platelet hyperactivity in DM by impeding mitophagy. As such, FUNDC1-midiated mitophagy may be a promising target for the treatment of DM and its associated cardiovascular complications related cardiovascular events.

Dexamethasone inhibits IL-8 via glycolysis and mitochondria-related pathway to regulate inflammatory pain

BACKGROUND

Dexamethasone (Dexa) has been recently found to exert an analgesic effect, whose action is closely related to IL-8. However, whether dexamethasone induces antinociception via glycolysis and mitochondria-related pathways is still unclear.

METHODS

Right hind paw inflammatory pain in mice was induced by intraplantar injection of Freund's Complete Adjuvant (FCA). Von Frey test was then used to measure the paw withdrawal threshold. The detection of glycolysis and mitochondrial pathway-related proteins and IL-8 were determined by Western blot and ELISA. The potential interaction between Dexa and fructose-1,6-bisphosphate (FBP, a PKM2 activator) was examined by simulation predictions using molecular docking.

RESULTS

Intrathecal administration of Dexa (20 µg/20 µL) had an obvious analgesic effect in FCA-treated mice, which was counteracted by the glycolysis inhibitor 2-deoxyglucose (2-DG, 5 mg/20 µL) or the mitochondria-related pathway inhibitor oligomycin complex (Oligo, 5 µg/20 µL). In the glycolysis pathway, Dexa decreased GLUT3 and had no impact on HIF-1α expression during FCA-induced inflammation. Additionally, Dexa further increased the PKM2 level, accompanied by the formation of hydrogen bonds between Dexa and the PKM2 activator fructose-1,6-bisphosphate (FBP). In the mitochondrial pathway, Dexa downregulated the expression of Mfn2 protein but not the PGC-1α and SIRT-1 levels in the spinal cord. Moreover, both 2-DG and Oligo decreased Mfn2 expression. Finally, IL-8 level was reduced by the single or combined administration of Dexa, 2-DG, and Oligo.

CONCLUSION

Dexa attenuated IL-8 expression via glycolysis and mitochondrial pathway-related proteins, thus mediating the analgesic effect during inflammatory pain.