Downregulating lncRNA MIAT attenuates apoptosis of podocytes exposed to high glucose

Investigation of TNF and related lncRNAs in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is a significant driver of end-stage renal disease, requiring kidney replacement therapies such as transplantation and dialysis. Given the critical importance of understanding the onset and progression of DN, we sought to explore the expression levels of tumor necrosis factor (TNF) and related long noncoding RNAs (lncRNAs) in diabetic patients with and without DN, as well as in pre-diabetic individuals, compared to healthy controls. We further explored the involvement of TNF and TNF-related lncRNAs in high glucose (HG)-induced apoptosis of human embryonic kidney (HEK)-293 cells.

MATERIAL AND METHOD

In the current cross-sectional investigation, we compare the expression levels of lncRNA myocardial infarction-associated transcript (MIAT), lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1), and TNF in 50 healthy individuals, 50 people with prediabetes, 50 patients with type 2 diabetes mellitus (T2DM), and 50 patients with T2DM- DN. We cultured HEK293 cells in a HG condition (100 mM glucose) to establish a cellular model of DN, while HEK293 cells cultured in a normal-glucose environment (5 mM glucose) served as controls. We further assess apoptosis in HEK293 cells via flow cytometry analysis. Moreover, we evaluated the expression levels of lncRNA MIAT, lncRNA NEAT1, and TNF in HG and normal-glucose (NG) groups to investigate their potential involvement in HEK293 cell apoptosis and the pathogenesis of DN.

RESULT

Our findings reveal a significant upregulation of lncRNA MIAT, lncRNA NEAT1, and TNF in T2DM and T2DM-associated DN groups compared to prediabetic individuals and healthy controls (p < 0.05). Furthermore, HG conditions significantly increased the apoptotic rate of HEK293 cells. Additionally, the expression levels of TNF, lncRNA MIAT, and lncRNA NEAT1 were increased in HEK-293 cells cultured in a HG.

CONCLUSION

In conclusion, our findings indicate a significant role for the TNF gene and associated lncRNAs, such as lncRNA MIAT and lncRNA NEAT1, in podocyte apoptosis and the development of DN.

Astragalus polysaccharide attenuates diabetic nephropathy by reducing apoptosis and enhancing autophagy through activation of Sirt1/FoxO1 pathway

OBJECTIVE

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease in diabetic patients. Astragalus polysaccharide (APS) is a natural active ingredient in Astragalus membranaceus with anti-hypertensive and anti-oxidative properties. This study aimed to explore the protective roles of APS and its underlying mechanisms in DN.

METHODS

After the establishment of a rat model of DN by a high-fat diet and treatment with 30 mg/kg streptozotocin (STZ), the effects of 100 mg/kg APS on the levels of serum creatinine, blood urea nitrogen, blood glucose, and urinary albumin-to-creatinine ratio were measured. Histopathological alterations in renal tissues, renal cell apoptosis, renal inflammation, and oxidative stress were examined. The impacts of 0-200 μg/mL APS on the viability and apoptosis in high glucose (HG)-stimulated podocytes were measured by Cell Counting Kit-8 assays and flow cytometry, respectively. The expression of genes was tested by immunoblotting, quantitative real-time PCR, and immunofluorescence staining.

RESULTS

APS enhanced the expression of podocin and nephrin, increased viability, and reduced apoptosis in HG-induced podocytes. APS treatment abrogated high glucose-mediate suppression of autophagy in podocytes by activating the Sirt1/FoxO1 pathway. The Sirt1 inhibitor EX-527 eliminated the ameliorative effects of APS on renal dysfunction and renal tissue damage, as well as the inhibitory effects of APS on oxidative stress, inflammation, and apoptosis in DN rats. Moreover, EX-527 inhibited APS-induced autophagy activation in DN rats.

CONCLUSION

APS mitigated DN under hyperglycemic conditions by activating the Sirt1/FoxO1 autophagy pathway, suggesting that APS is a promising agent for DN treatment.