Yan-Ping Gu’s research while affiliated with Xuzhou Medical College and other places

Diabetic nephropathy (DN) closely relates to morphological and functional changes of podocytes, and anaerobic glycolysis represents the predominant energy source of podocytes. However, it is unknown whether lactate accumulation in chronic high glucose causes epithelial-mesenchymal transition (EMT) of podocytes through lactate-derived histone lysine lactylation (HKla). Lactate levels increased in high glucose-stimulated mouse podocyte cell line MPC and blood and the kidney of diabetic mice. High glucose or exogenous lactate decreased nephrin levels while increased collagen IV and HKla levels in MPC, but co-treatment with oxamate or dichloroacetate reduced lactate levels and alleviated the decreases in nephrin and zonula occludens- 1 levels and the increases in collagen IV and α-smooth muscle actin as well as HKla levels in high glucose-cultured MPC. However, co-treatment with rotenone diversely affected these indices. Eleven intersection genes were screened in lactate raising and lowering interventions in podocytes using RNA sequencing and four genes were validated by qPCR. Furthermore, lactate-lowering treatments attenuated renal functions, EMT, and histone lactylation in the kidney of diabetic mice. Additionally, the increased lactate might result from the upregulated monocarboxylate transporter 2 in the mitochondria and the decreased pyruvate dehydrogenase activity. Together, we reveal the role of histone lactylation in driving the EMT phenotype of podocytes in chronic high glucose state, subsequently promoting the pathological process of DN. Our study provides a reference for the study of the relationship between lactate-induced histone lactylation modification and diabetic complications.

Bitter taste receptors (TAS2Rs) Tas2r108 gene possesses a high abundance in mouse kidney; however, the biological functions of Tas2r108 encoded receptor TAS2Rs member 4 (TAS2R4) are still unknown. In the present study, we found that mouse TAS2R4 (mTAS2R4) signaling was inactivated in chronic high glucose-stimulated mouse podocyte cell line MPC, evidenced by the decreased protein expressions of mTAS2R4 and phospholipase C β2 (PLCβ2), a key downstream molecule of mTAS2R4 signaling. Nonetheless, agonism of mTAS2R4 by quinine recovered mTAS2R4 and PLCβ2 levels, and increased podocyte cell viability as well as protein expressions of ZO-1 and nephrin, biomarkers of podocyte slit diaphragm, in high glucose-cultured MPC cells. However, blockage of mTAS2R4 signaling with mTAS2R4 blockers γ-aminobutyric acid and abscisic acid, a Gβγ inhibitor Gallein, or a PLCβ2 inhibitor U73122 all abolished the effects of quinine on NLRP3 inflammasome and p-NF-κB p65 as well as the functional podocyte proteins in MPC cells in a high glucose condition. Furthermore, knockdown of mTAS2R4 with lentivirus-carrying Tas2r108 shRNA also ablated the effect of quinine on the key molecules of the above inflammatory signalings and podocyte functions in high glucose-cultured MPC cells. In summary, we demonstrated that activation of TAS2R4 signaling alleviated the podocyte injury caused by chronic high glucose, and inhibition of NF-κB p65 and NLRP3 inflammasome mediated the protective effects of TAS2R4 activation on podocytes. Moreover, activation of TAS2R4 signaling could be an important strategy for prevention and treatment of diabetic kidney disease.

Background and Purpose: Diabetic nephropathy (DN) closely relates to morphological and functional changes in podocytes, and anaerobic glycolysis represents the predominant energy source of podocytes. However, it is unknown whether lactate accumulation in chronic high glucose caused epithelial-mesenchymal transition (EMT) of podocytes through lactate-derived histone lactylation. Experimental Approach: We examined biomarkers of podocytes and mesenchymal cells as well as lactylation of histone lysine residues (HKla) in mouse MPC cells cultured with high glucose (HG) or lactate (LA). Moreover, these indices were observed in MPCs after HG co-culture with multiple interventions of lactate levels, and differently expressed genes (DEGs) were screened using RNA sequencing. Finally, renal pathological characteristics and histone lactylation were investigated in diabetic mice with lactate-lowering treatments. Key Results: Both HG and LA decreased nephrin levels while increased collagen IV levels in MPCs, and HG and LA stimulation synchronously elevated HKla levels. However, co-treatment with oxamate or dichloroacetate reducing lactate levels alleviated decreases in nephrin and ZO-1 levels and increases in collagen IV and α smooth muscle actin levels as well as HKla levels in HG-cultured MPCs, but co-treatment with rotenone diversely affected these indices. RNA sequencing found eleven DEGs in HG-cultured MPCs after oxamate or dichloroacetate intervention and qPCR experiments validated four of them. Importantly, oxamate or dichloroacetate treatment attenuated renal functions, EMT, and histone lactylation in kidney of diabetic mice. Conclusion and Implications: This study clarified that lactate mediated chronic high glucose-caused podocyte EMT through lactate-induced histone lactylation, and then promoted the pathological process of DN.