Lactate programs PBX1 lactylation and mesangial proliferation in lupus nephritis
Enzhuo Liu, Chenghua Weng, Chenchu Yan, Xingchen Zhu, Xinyue Li, Mengdi Liu, Zhenke Wen, Zhichun Liu
Enzhuo Liu, Chenghua Weng, Chenchu Yan, Xingchen Zhu, Xinyue Li, Mengdi Liu, Zhenke Wen, Zhichun Liu
View: Text | PDF
Research Article Metabolism

Lactate programs PBX1 lactylation and mesangial proliferation in lupus nephritis

Abstract

Lupus nephritis (LN) constitutes the most common organ-threatening manifestation of systemic lupus erythematosus (SLE), with the pathological proliferation of mesangial cells (MCs) recognized as a critical factor in its pathogenesis and progression. Self-DNA-containing immune complex (DNA-IC) represents a prime pathogenic factor in SLE, yet its pathological effect on MCs remains unclear. In the present study, we elucidated the mechanism underlying the excessive proliferation of MCs following the recognition of DNA-IC in patients with LN. Here, we pinpointed that the excessive proliferation of MCs was attributed to an anomalous transition from the G1 to the S phase of the cell cycle in patients with LN. Mechanically, the dysfunction of P27 protein resulted in the aberrant G1-S phase transition, and the phenomenon was closely related to the ubiquitin-mediated degradation of its key transcription factor, PBX1. This degradation was regulated by lactylation of PBX1 in the site of Lys40 residue. The elevated lactylation level of PBX1 protein was caused by the upregulation of glycolysis levels induced by DNA-IC. Accordingly, targeting lactate production in MCs from patients with LN effectively alleviated their renal inflammation and fibrosis progression. Elevated lactate resulted in PBX1 lactylation, leading to excessive proliferation of MCs and, thus, serving as a promising therapeutic target for LN.

Authors

Enzhuo Liu, Chenghua Weng, Chenchu Yan, Xingchen Zhu, Xinyue Li, Mengdi Liu, Zhenke Wen, Zhichun Liu

×

Figure 4

Lactate promotes PBX1 ubiquitination in MCs.

Options: View larger image (or click on image) Download as PowerPoint
Lactate promotes PBX1 ubiquitination in MCs. (A) Gene set enrichment ana...
(A) Gene set enrichment analysis of single-cell data from SDY997, showing that MCs in patients with LN were enriched in genes involved in glycolysis progress. NES, normalized enrichment score. (B) mRNA expression of differential genes that regulate key catalytic enzymes involved in the glycolysis progress was compared between LN and HC MCs by RT-qPCR (n = 11 for each group). (C) Detection of lactate production levels in intracellular lactate content and extracellular lactate release in both LN and HC MCs (n = 6 for each group). (D) Representative Western blot analysis of LDHA protein level in LN and HC MCs (n = 4). (E and F) LN MCs were transfected with LDHA shRNA. Cell proliferation was detected using the CCK-8 assay, and protein level of PBX1 was determined using immunoblots. (G–I) MCs were stimulated with sodium L-lactate for 1 day. (G and H) MCs were stimulated in the presence or absence of sodium L-lactate (30 mM) and tested for protein level of PBX1 and its combination capacity with TRIM21. (I) The proliferation induced by sodium L-lactate was rescued upon P27 overexpression, as reflected by the CCK-8 assay. Lines with whiskers show the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 with ANOVA plus Turkey’s method (F) and paired t test (B–E and I). In all cases, for a given condition, representative Western blot images are from the same sample, although the target proteins may have been probed on separate membranes to facilitate clear visualization.