The role of TET2-mediated ROBO4 hypomethylation in the development of diabetic retinopathy

Research progress of the effective active ingredients of Astragalus mongholicus in the treatment of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is one of the most prevalent consequences of diabetes, with a high incidence and disability rate. The DPN's pathogenesis is extremely complex and yet to be fully understood. Persistent high glucose metabolism, nerve growth factor deficiency, microvascular disease, oxidative stress, peripheral nerve cell apoptosis, immune factors, and other factors have been implicated in the pathogenesis of DPN. Astragalus mongholicus is a commonly used plant used to treat DPN in clinical settings. Its rich chemical components mainly include Astragalus polysaccharide, Astragalus saponins, Astragalus flavones, etc., which play a vital role in the treatment of DPN. This review aimed to summarize the pathogenesis of DPN and the studies on the mechanism of the effective components of Astragalus mongholicus in treating DPN. This is of great significance for the effective use of Chinese herbal medicine and the promotion of its status and influence on the world.

Hypoxia-induced P4HA1 overexpression promotes post-ischemic angiogenesis by enhancing endothelial glycolysis through downregulating FBP1

BACKGROUND

Angiogenesis is essential for tissue repair in ischemic diseases, relying on glycolysis as its primary energy source. Prolyl 4-hydroxylase subunit alpha 1 (P4HA1), the catalytic subunit of collagen prolyl 4-hydroxylase, is a glycolysis-related gene in cancers. However, its role in glycolysis-induced angiogenesis remains unclear.

METHODS

P4HA1 expression was modulated using adenoviruses. Endothelial angiogenesis was evaluated through 5-ethynyl-2'-deoxyuridine incorporation, transwell migration, and tube formation assays in vitro. In vivo experiments measured blood flow and capillary density in the hindlimb ischemia (HLI) model. Glycolytic stress assays, glucose uptake, lactate production, and quantitative reverse transcription-polymerase chain reaction (RT-PCR) were employed to assess glycolytic capacity. Transcriptome sequencing, validated by western blotting and RT-PCR, was utilized to determine underlying mechanisms.

RESULTS

P4HA1 was upregulated in endothelial cells under hypoxia and in the HLI model. P4HA1 overexpression promoted angiogenesis in vitro and in vivo, while its knockdown had the opposite effect. P4HA1 overexpression reduced cellular α-ketoglutarate (α-KG) levels by consuming α-KG during collagen hydroxylation. Downregulation of α-KG reduced the protein level of a DNA dioxygenase, ten-eleven translocation 2 (TET2), and its recruitment to the fructose-1,6-biphosphatase (FBP1) promoter, resulting in decreased FBP1 expression. The decrease in FBP1 enhanced glycolytic metabolism, thereby promoting endothelial angiogenesis.

CONCLUSIONS

Hypoxia-induced endothelial P4HA1 overexpression enhanced angiogenesis by promoting glycolytic metabolism reprogramming through the P4HA1/α-KG/TET2/FBP1 pathway. The study's findings underscore the significance of P4HA1 in post-ischemic angiogenesis, suggesting its therapeutic potential for post-ischemic tissue repair.

TET2-mediated ECM1 hypomethylation promotes the neovascularization in active proliferative diabetic retinopathy

BACKGROUND

Studies have shown that tet methylcytosine dioxygenase 2 (TET2) is highly expressed in diabetic retinopathy (DR), which reduces the DNA methylation of downstream gene promoters and activates the transcription. Abnormally expressed TET2 and downstream genes in a high-glucose environment are associated with retinal capillary leakage and neovascularization. Here, we investigated the downstream genes of TET2 and its potential association with neovascularization in proliferative diabetic retinopathy (PDR).

METHODS

GSE60436, GSE57362, and GSE158333 datasets were analyzed to identify TET2-related hypomethylated and upregulated genes in PDR. Gene expression and promoter methylation of these genes under high glucose treatment were verified. Moreover, TET2 knockdown was used to assess its impact on tube formation and migration in human retinal microvascular endothelial cells (HRMECs), as well as its influence on downstream genes.

RESULTS

Our analysis identified three key genes (PARVB, PTPRE, ECM1) that were closely associated with TET2 regulation. High glucose-treated HRMECs exhibited increased expression of TET2 and ECM1 while decreasing the promoter methylation level of ECM1. Subsequently, TET2 knockdown led to decreased migration ability and tube formation function of HRMECs. We further found a decreased expression of PARVB, PTPRE, and ECM1, accompanied by an increase in the promoter methylation of ECM1.

CONCLUSIONS

Our findings indicate the involvement of dysregulated TET2 expression in neovascularization by regulating the promoter methylation and transcription of downstream genes (notably ECM1), eventually leading to PDR. The TET2-induced hypomethylation of downstream gene promoters represents a potential therapeutic target and offers a novel perspective on the mechanism underlying neovascularization in PDR.

Applicability of mesenchymal stem cell-derived exosomes as a cell-free miRNA therapy and epigenetic modifiers for diabetes

Given that exosome nanovesicles constitute various growth factors, miRNAs and lncRNAs, they have implications for epigenetic modifications. Few studies have shown that exosomes from mesenchymal stem cells (MSCs) exhibit therapeutic effects on diabetic complications by substituting miRNAs and regulating histone modifications. Therefore, reversing epigenetic aberrations in diabetes may provide new insight into its treatment. This review discusses the impact of DNA and histone methylations on the development of diabetes and its complications. Further, we talk about miRNAs dysregulated in diabetic conditions and the possibility of utilizing mesenchymal stem cell (MSC) exosomes for the development of miRNA cell-free therapy and epigenetic modifiers in reversing diabetic-induced epigenetic alterations.