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During the congress, E-Posters will be accessible to all participants on the congress website 24/7, as well as in the E-poster stations in the congress center.
Preparing your E-Poster
Please review the E-Poster format requirements carefully when preparing your E-Poster. Should your E-Poster not meet the mentioned requirements, it may not be displayed as described above.
E-Poster Submission Deadline
Please prepare and upload your E-Poster no later than March 14, 2026 11.59PM CET. After this date, you will no longer be able to prepare and upload your E-poster and it will not be displayed and accessible on the congress website.
Please follow the instructions below to input your abstract title.
Abstract titles should be brief and reflect the content of the abstract.
Acute kidney injury (AKI) after ischemia-reperfusion centers on proximal-tubule (PT) dysfunction and often progresses to chronic disease. Type-2 inositol-1,4,5-trisphosphate receptor (IP3R2) is an endoplasmic-reticulum (ER) Ca²⁺ channel enriched at mitochondria-associated ER membranes (MAMs) and has been linked to aging and cellular senescence, yet its influence on tubular stress responses remains unclear. This study aimed to elucidate a calcium-independent role of IP3R2 in regulating PT cell fate during anoxia-reoxygenation (AR) and ER-mitochondrial crosstalk.
HK-2 and primary RPTEC cultures underwent selective IP3R2 silencing by siRNA, 24-hour anoxia followed by 4-hour reoxygenation. Cell viability was assessed with CCK-8 and LDH assays, and poptosis was evaluated with Annexin V/7-AAD and with JC-1 to monitor mitochondrial membrane potential. Cell-cycle distribution was assessed by flow cytometry and immunoblotting of p27 and phosphorylated CDK2. Mitochondrial morphology was visualized with MitoTracker, while oxidative phosphorylation was profiled by Seahorse extracellular flux analysis of basal and maximal oxygen consumption rate (OCR) and ATP production. Intracellular Ca²⁺ dynamics were recorded with Fluo-4 AM and Fura-2 AM imaging. To explore molecular partners, co-immunoprecipitation mass spectrometry (co-IP/MS) was performed for IP3R isoforms (IP3R1/2/3), followed by over-representation analysis.
IP3R2 knockdown significantly improved HK-2 and RPTEC viability after AR and reduced early/late apoptosis by Annexin V and JC-1. AR prominently induced G1-phase arrest with p27 upregulation. Crucially, IP3R2 knockdown effectively alleviated this AR-induced G1 arrest, blunted p27 accumulation, and restored CDK2 phosphorylation, consistent with improved G1/S progression. IP3R2 knockdown preserved mitochondrial morphology and maintained bioenergetic competence despite modestly lower maximal respiration and ATP-linked OCR, indicating adaptive energy conservation rather than failure. The induction of senescence-associated secretory phenotype (SASP: TGF-β1 and IL-6) by AR was also significantly ameliorated by IP3R2 knockdown. Notably, these protective effects occurred without significant changes in global cytosolic or mitochondrial Ca²⁺ flux. Importantly, co-IP/MS showed that IP3R2 pulldowns, unlike IP3R1/3, were enriched for proteins annotated to cell-cycle checkpoints, consistent with a potential checkpoint-linked module at MAMs.
Our findings unveil a novel calcium flux-independent role for IP3R2 in preserving renal proximal tubular cell survival after AR injury. IP3R2 appears to modulate cell cycle progression by interacting with the cell cycle inhibitor p27, thereby preventing AR-induced G1 arrest and subsequent apoptosis. These results provide new insights into calcium-independent mechanisms of ER-mitochondrial crosstalk in tubular injury.
