Abstract: SA-PO163
Exposure of Viable Proximal Tubular Epithelial Cells (PTEC) to Apoptotic Cells Enhances Activation of Mixed-Lineage Kinase-3 (MLK-3) in PTEC
Session Information
- AKI: Metabolism and Cell Death
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Park, Sunho, University of Illinois Chicago, Chicago, Illinois, United States
- Jha, Saket, University of Illinois Chicago, Chicago, Illinois, United States
- Kumar, Sandeep, University of Illinois Chicago, Chicago, Illinois, United States
- Mahendiran, Sowdhamini, University of Illinois Chicago, Chicago, Illinois, United States
- Singh, Sunil Kumar, University of Illinois Chicago, Chicago, Illinois, United States
- Srivastava, Piush, University of Illinois Chicago, Chicago, Illinois, United States
- Rana, Ajay, University of Illinois Chicago, Chicago, Illinois, United States
- Levine, Jerrold S., University of Illinois Chicago, Chicago, Illinois, United States
Background
We have previously shown that receptor-mediated recognition of apoptotic targets by viable PTEC induces caspase 8- and BID-dependent apoptotic death of the PTEC. The signaling intermediates between target recognition and caspase-8 activation remain unknown. Separate studies have shown that MLK-3 mediates the death of kidney epithelial cells in response to a variety of toxic and inflammatory stimuli. We therefore hypothesized that MLK-3 may play a role in target-dependent death of PTEC.
Methods
BU.MPT cells, a conditionally immortalized PTEC line, were used as both viable responding cells and apoptotic targets. Responder cells were exposed to targets for 30 mins, followed by washing. Responder cells were then treated with vehicle, TNF-a, LPS, or both for 15 mins, either immediately after washing or after overnight incubation.
Results
Exposure to apoptotic targets led to increased activity of MLK-3, as shown by increased phosphorylation of MLK-3 and its downstream target JNK, on both Western blotting and immunofluorescence microscopy. The degree of MLK-3 activation was equal to or exceeded that induced by TNF-a and/or LPS. Activation by apoptotic targets alone occurred immediately after target exposure and persisted despite overnight exposure in the absence of targets.
Conclusion
We have shown that exposure of viable PTEC to apoptotic targets leads to activation of MLK-3, a kinase known to enhance the death of PTEC to a variety of injurious stimuli. Additional studies involving the overexpression or inhibition of MLK-3 are planned to determine whether MLK-3 is a key signaling intermediate connecting receptor mediated recognition of apoptotic targets and caspase 8-dependent apoptotic death. As most therapies for acute kidney injury (AKI) fail because efficacy depends on their administration before injury, activation of MLK-3 by apoptotic targets offers great promise because this mechanism of PTEC death is initiated after injury occurs.
Funding
- Other NIH Support