Transcriptomics of S3 segment in mice: response to type 1 diabetes, SGLT1/2 inhibition, or GLP1 receptor agonism

Inhibitors of SGLT2 (SGLT2is) and diabetes enhance glucose delivery and reabsorption in late proximal tubule S3 segments. Molecular consequences remain poorly understood. Here, we determined transcriptomic changes in S3 segments of male adult DBA wild-type (WT) and littermate diabetic Akita mice ± Sglt1 knockout (Sglt1-KO) given vehicle or SGLT2i dapagliflozin for 2 wk, and in Akita mice receiving glucagon-like peptide-1 receptor (GLP1R) agonist (GLP1RA) semaglutide. RNA sequencing was performed in S3 segments isolated by immunostaining-guided laser-capture-microdissection in deep cortex/outer medulla. Among 19,068 detected annotated genes, 838 genes were differentially expressed by SGLT2is in WT (differentially expressed genes; DEGs; P < 0.05) and 1,410 genes in Akita vs. WT. Approximately 34% of SGLT2i-sensitive genes changed in the same direction in Akita. Both maneuvers upregulated pathways of cellular proliferation (confirmed by phospho-Ser10 Histone H3 staining) and cellular response to stress, while downregulating pathways of immune/inflammatory response, cytokine production/receptor signaling, and cell adhesion/migration. Both maneuvers also induced unique responses. Unique pathway responses to SGLT2is in WT included an increase in DNA dealkylation/demethylation and lysosomal acidification, and reduced valine biosynthesis. Differences in SGLT1-dependency of responses to Akita vs. SGLT2is in WT suggested different initiating mechanisms. In Akita, SGLT2is, Sglt1-KO, and GLP1R agonism restored 12%, 18%, and 25% of DEGs, respectively; combined SGLT2i/Sglt1-KO was not synergistic. Akita downregulated whole kidney SGLT1 membrane expression, potentially to limit glucose-induced stress. GLP1RA reduced/restored cellular stress response and proliferation in Akita in S3 segments, associated with enhanced/restored kidney membrane expression of SGLT1. Finally, Akita-sensitive genes unresponsive to any of the three maneuvers were identified that may indicate new therapeutic avenues.NEW & NOTEWORTHY Both SGLT2 inhibition and diabetes increase glucose delivery to late proximal tubule S3 segments. Using transcriptomic mapping in mice, we found that both conditions induce cellular proliferation and stress responses while suppressing inflammatory pathways, but also trigger unique responses. Responses differed in their SGLT1-dependency, suggesting different initiating mechanisms. Diabetes suppressed SGLT1 expression, potentially to limit glucose-induced stress. Glucagon-like peptide-1 receptor (GLP1R) agonism reversed many diabetic transcriptomic changes in S3 segments, including stress response, associated with restored SGLT1 expression.