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Updated: Apr 26, 2026
Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes
Published on: January 7, 2013
Protein kinase CK2 inhibition induces cell death via early impact on mitochondrial function
Fatima Qaiser1, Janeen H Trembley, Betsy T Kren
1Cellular and Molecular Biochemistry Research Laboratory (151), Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota, 55417; Department of Laboratory Medicine and Pathology, University of Minnesota School of Medicine, Minneapolis, MN, 55455; Department of Biochemistry and Molecular Biology, Army Medical College, National University of Sciences and Technology, Islamabad, Pakistan.
Abstract:
CK2 (official acronym for casein kinase 2 or II) is a potent suppressor of apoptosis in response to diverse apoptotic stimuli-thus its molecular downregulation or activity inhibition results in potent induction of cell death. CK2 downregulation is known to impact mitochondrial apoptotic circuitry but the underlying mechanism(s) remain unclear. Utilizing prostate cancer cell lines subjected to CK2-specific inhibitors which cause loss of cell viability, we have found that CK2 inhibition in cells causes rapid early decrease in mitochondrial membrane potential (Δψm). Cells treated with the CK2 inhibitors TBB (4,5,6,7-tetrabromobenzotriazole) or TBCA (tetrabromocinnamic acid) demonstrate changes in Δψm which become apparent within 2 h, that is, significantly prior to evidence of activation of other mitochondrial apoptotic signals whose temporal expression ensues subsequent to loss of Δψm. Further, we have demonstrated the presence of CK2 in purified mitochondria and it appears that the effect on Δψm evoked by inhibition of CK2 may involve mitochondrial localized CK2. Results also suggest that alterations in Ca(2+) signaling may be involved in the CK2 mediated regulation of Δψm and mitochondrial permeability. Thus, we propose that a key mechanism of CK2 impact on mitochondrial apoptotic circuitry and cell death involves early loss of Δψm which may be a primary trigger for apoptotic signaling and cell death resulting from CK2 inhibition.
Insights
Casein kinase 2 (CK2) inhibition triggers cell death by rapidly decreasing mitochondrial membrane potential (Δψm). This early Δψm loss, potentially mediated by mitochondrial CK2, precedes other apoptotic signals, suggesting a key role in cell death induction.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Casein kinase 2 (CK2) is a critical regulator of apoptosis, suppressing cell death.
- CK2 downregulation or inhibition potently induces apoptosis.
- The precise mechanisms by which CK2 impacts mitochondrial apoptotic pathways are not fully understood.
Purpose of the Study:
- To elucidate the early molecular events following CK2 inhibition that lead to cell death.
- To investigate the role of mitochondrial membrane potential (Δψm) in CK2-mediated apoptosis.
- To determine if mitochondrial-localized CK2 is involved in regulating Δψm.
Main Methods:
- Utilized prostate cancer cell lines treated with CK2-specific inhibitors (TBB, TBCA).
- Monitored mitochondrial membrane potential (Δψm) using established assays.
- Investigated the presence and localization of CK2 within purified mitochondria.
- Assessed alterations in calcium (Ca2+) signaling.
Main Results:
- CK2 inhibition rapidly decreased Δψm within 2 hours in prostate cancer cells.
- This Δψm loss occurred significantly before other mitochondrial apoptotic signals.
- CK2 was detected in purified mitochondria, suggesting a role for mitochondrial CK2.
- Evidence suggests Ca2+ signaling alterations may be involved in regulating Δψm.
Conclusions:
- Early loss of Δψm is a primary mechanism by which CK2 inhibition induces apoptosis.
- Mitochondrial-localized CK2 likely plays a role in regulating Δψm.
- CK2 inhibition triggers cell death through early disruption of mitochondrial function, potentially involving Ca2+ signaling.
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