Controls Gene Transcription and Spliceosome

podocyte. Conclusions: The integrative strategy can help us to efficiently use the publicly available transcriptomics resources. Using this approach and combining with classical research methods, we identified TEKT2 and PIAS2 , two spermatogenesis-related genes involved in the pathogenesis of DN. Furthermore, TEKT2 is involved in this pathogenesis by regulating the podocyte cytoskeleton

Background: Insulin signalling to the podocyte via the cognate insulin receptor (IR) is crucial for kidney function and insulin-like growth factor 1 (IGF1) signalling through the structurally related insulin-like growth factor 1 receptor (IGF1R) is also known to directly affect the podocyte.Since the IR and IGF1R may act redundantly in some contexts, this study sought to elucidate the role of the insulin/IGF1 axis in podocyte function using mouse and cell culture models deficient in both receptors.
Methods: To examine the effects of combined receptor loss in vivo, a transgenic mouse model with conditional inactivation of podocyte IR and IGF1R was generated.In vitro, conditionally immortalized genetic IR/IGF1R dual knockout podocytes were characterised using proteomic, transcriptomic and metabolomic analysis.
Results: Podocyte specific IR/IGF1R knockout mice developed significant albuminuria and a severe renal phenotype with global sclerosis, renal failure and death occurring between 4 and 24 weeks.>90% loss of the IR and IGF1R in cultured mouse podocytes was also detrimental resulting in >50% cell death 7 days after receptor gene excision.Enrichment analysis of total proteomic data revealed a striking downregulation of gene ontology terms associated with splicing and RNA processing activity in IR/IGF1R deficient cells.Genome-wide and targeted long-read RNA sequencing was performed to further explore the effect of dual receptor suppression on spliceosome function alongside metabolomic studies to elucidate key metabolic pathways regulated by these receptors.
Conclusions: This work underlines the critical importance of podocyte insulin/IGF signalling and reveals a novel role for this signalling axis in RNA processing by regulating spliceosome activity.

SA-PO234 Poster Saturday
Diabetic Kidney Disease: Basic -II

Decoy Receptor 2 Mediates the Apoptosis-Resistant Phenotype of Senescent Renal Tubular Cells and Accelerates Renal Fibrosis in Diabetic Nephropathy
Jia Chen.Army Medical Center of PLA, Chongqing, China.
Background: Apoptotic resistance leads to persistent accumulation of senescent cells and sustained expression of a senescence-associated secretory phenotype, playing an essential role in the progression of tissue fibrosis.However, whether senescent renal tubular epithelial cells (RTECs) exhibit an apoptosis-resistant phenotype and the mechanism remain unclear.
Methods: A total of 241 DN patients diagnosed by biopsy in our hospital from January 2012 to December 2019 were included.The STZ-induced DN mouse model was constructed.DcR2-siRNA and DcR2 overexpression plasmids were transfected into the kidney using ultrasonic microbubble technology.TECs senescence was constructed by high glucose treatment.The co-localization of DcR2 and apoptosis-related markers (FLIP, Bcl-2, caspase-3, caspase-8, Tunel) and fibrotic markers (a-SMA, collagen IV, fibronectin) were analyzed.DcR2 interacting proteins were screened and analyzed by co-immunoprecipitation combined with quantitative proteomics in renal tissue from DN patients and TECs.
Results: DcR2 was co-localized with fibrotic markers, and anti-apoptotic proteins FLIP and Bcl2 but rarely co-localized with caspase 3 or TUNEL.DcR2 overexpression promoted renal fibrosis in mice with STZ-induced DN, as evidenced by augmented Masson staining and upregulated expression of fibrotic markers.DcR2 overexpression also enhanced FLIP expression while reducing the expression of pro-apoptotic proteins, resulting in apoptotic resistance.In contrast, DcR2 knockdown produced the opposite effects in vitro and in vivo.Moreover, quantitative proteomics demonstrated that DcR2 interacted with GRP78, which has been shown to promote apoptotic resistance in cancer.GRP78 exhibited co-localization with senescent and anti-apoptotic markers but was rarely co-expressed with caspase 3 or TUNEL.Additionally, GRP78 knockdown decreased the apoptosis resistance of HG-induced senescent RTECs with upregulated cleaved caspase 3 and increased the percentage of apoptotic RTECs.Mechanistically, DcR2 mediated apoptotic resistance in senescent RTECs by enhancing GRP78-caspase 7 interactions and promoting Akt phosphorylation.
Conclusions: DcR2 mediated the apoptotic resistance of senescent RTECs and renal fibrosis by interacting with GRP78, indicating that targeting the DcR2-GRP78 axis represents a promising therapeutic strategy for DN.

SA-PO235 Poster Saturday
Diabetic Kidney Disease: Basic -II Tyro3 Agonist as a Novel Therapy for Glomerular Disease Fang Zhong, Hong Cai, Kyung Lee, John C. He.Icahn School of Medicine at Mount Sinai, New York, NY.
Background: Drugs directly targeting podocytes as a therapy for glomerular disease are still lacking.Our previous studies suggest that Tyro3 is a podocyte-specific TAM (Tyro3, Axl, MertK) tyrosine kinase receptor.In human, glomerular Tyro3 expression negatively correlates with the progression of primary glomerular disease and diabetic kidney disease (DKD).Knockout of Tyro3 aggravates podocyte injury in Adriamycininduced nephropathy (ARDN) and DKD mice while induction of Tyro3 expression in