Transcriptomics of SGLT2-positive early proximal tubule segments in mice: response to type 1 diabetes, SGLT1/2 inhibition or GLP1 receptor agonism

SGLT2 inhibitors (SGLT2i) and GLP1 receptor (GLP1R) agonists have kidney protective effects. To better understand their molecular effects, RNA sequencing was performed in SGLT2-positive proximal tubule segments isolated by immunostaining-guided laser capture microdissection. Male adult DBA wildtype (WT) and littermate diabetic Akita mice ± Sglt1 knockout (Sglt1-KO) were given vehicle or SGLT2i dapagliflozin (dapa; 10mg/kg diet) for 2 weeks, and other Akita mice received GLP1R agonist semaglutide (sema; 3nmol/[kg body weight*day], s.c.). Dapa (254±11mg/dL) and Sglt1-KO (367±11mg/dL) but not sema (407±44mg/dL) significantly reduced hyperglycemia in Akita mice (480±33mg/dL). The 20,748 detected annotated protein-coding genes included robust enrichment of S1-segment marker genes. Akita showed 198 (~1%) differentially expressed genes vs. WT (DEGs; adjusted p<0.1) including downregulation of anionic transport, unsaturated fatty acid and carboxylic acid metabolism. Dapa changed only 2 genes in WT but restored 43% of DEGs in Akita, including upregulation of lipid metabolic pathway, carboxylic acid metabolism and organic anion transport. In Akita, sema restored ~10% of DEGs, and Sglt1-KO and dapa were synergistic (restored ~61%) possibly involving additive blood glucose effects (193±15mg/dl). Targeted analysis of transporters and channels (t-test p<0.05) revealed that ~10% of 526 detectable transporters and channels were downregulated by Akita, with ~60% restored by dapa. Dapa, dapa+Sglt1-KO and sema also altered Akita-insensitive genes. Among DEGs in Akita, ~30% were unresponsive to any treatment, indicating potential new targets. In conclusion, SGLT2i restored transcription for multiple metabolic pathways and transporters in SGLT2-positive proximal tubule segments in diabetic mice, with a smaller effect also observed for GLP1R agonism. Fourteen week old non-diabetic DBA male mice (Ins2+/+) with Sgl1+/+ or Sglt1-/- were treated with vehicle or dapagliflozin (10mg/kg diet) for 2 weeks, and littermate diabetic DBA male mice (Ins2 Akita/+) with Sglt1+/+ or Sglt1-/- were treated with vehicle, dapagliflozin (10mg/kg idet) or semaglutide (3nmol/kg body weight per day), subcutaneous injection) for 2 weeks. SGLT2-positive early proximal tubules were isolated by laser capture microdissection for RNA sequencing.