Fig. 5: SGLT2 as a 1,5-AG transporter in the kidney.

A Differentially expressed proteins of kidney tissues in UUO vs Sham are highlighted with volcano plot. The blue dots indicate the downregulated proteins, and the red dots indicate the upregulated proteins. B Western blot shows SGLT2 protein expression in kidneys from sham, UUO and UUO + BF (B. fragilis). C Quantitative analysis of panel B (n = 3). ***p = 0.0004 for SGLT2: Sham vs. UUO, **p = 0.0072 for SGLT2: Sham vs. UUO + BF, ^#p = 0.0394 for SGLT2: UUO vs. UUO + BF. D mRNA level of Slc5a2 was investigated in the GEO database using 153 subjects. Log-transformed SLC5A2 mRNA level was compared not only between glomeruli from healthy people (Normal) (n = 14) and lupus nephritic patients (LN) (n = 32), but also between tubulointerstitium from healthy people (n = 15) and lupus nephritic patients (n = 32) using Mann-Whitney U test; Log-transformed SLC5A2 mRNA level was compared not only between glomeruli from healthy people (n = 9) and hypertensive nephropathic patients (HN) (n = 9), but also between glomeruli from healthy people (n = 15) and IgA nephropathic patients (n = 27) using Mann-Whitney U test. **p = 0.0083 for Glomeruli HN; ***p < 0.0001 for Glomeruli LN; **p = 0.0096 for Glomeruli IgA; **p = 0.0091 for Tubulointerstitium LN. E mRNA level of SLC5A2 in the indicated groups (n = 6). ***p  < 0.0001 for Slc5a2: Sham vs. UUO, *p = 0.0140 for SGLT2: Sham vs. UUO + BF, ^#p = 0.0124 for SGLT2: UUO vs. UUO + BF. F The root mean square deviation (RMSD) of protein backbone atoms and 1,5-AG during the molecular dynamics (MD) simulation. G, H Molecular docking and the binding mode of 1,5-AG to SGLT2 through the MD simulation. I Empagliflozin significantly decreased the serum concentration of 1,5-AG in control mice (n = 10). ***p = 0.0003. Box plots show center line as median, whiskers show maxima and minima, and box limits show upper and lower quartiles. J Cellular uptake experiments of 1,5-AG-¹³C₆ were performed in stably SGLT2 transfected HEK293 vs wide-type (WT) cells (n = 6). ***p = 0.0022. Data are presented as mean ± SD. Comparison in D was performed with a two-tailed Mann-Whitney U test. Comparison in I and J were performed with a two-tailed Student’s t test. Comparisons in C, E were compared using One-Way ANOVA followed by Sidak’s multiple comparisons test. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001 (compared with sham group or normal subjects), ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 (compared with UUO group)^. Individual data points are independent biological replicates unless otherwise stated.