Related Experiment Video
Updated: Dec 12, 2025
Measuring Mitochondrial Function of Naïve and Effector CD8 T Cells
Published on: March 28, 2025
CARD19, the protein formerly known as BinCARD, is a mitochondrial protein that does not regulate Bcl10-dependent
Kariana E Rios1, Anuj K Kashyap2, Sean K Maynard1
1Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States.
Insights
The gene C9orf89 produces CARD19, a mitochondrial protein, not BinCARD-1. CARD19 does not significantly impact T cell receptor signaling or NF-κB activation despite its interaction with Bcl10.
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- The CARD11-Bcl10-Malt1 (CBM) complex is crucial for T cell receptor (TCR) signaling, activating NF-κB.
- Bcl10 degradation regulates NF-κB activation duration.
- Previous studies identified BinCARD-1 and BinCARD-2 (CARD19) as potential regulators of this pathway.
Purpose of the Study:
- To clarify the identity and function of C9orf89 gene products, specifically BinCARD-1 and CARD19.
- To investigate the role of CARD19 in T cell signaling pathways.
Main Methods:
- Analysis of cDNA AK057716 (BinCARD-1) and CARD19 (BinCARD-2) splicing.
- Immunoblotting to detect protein expression in T cells.
- Confocal microscopy to determine CARD19 localization.
- Overexpression studies in HEK293T cells.
- Assessment of NF-κB activation, Malt1 protease activity, and Bcl10 degradation in primary murine CD8 T cells after TCR engagement.
Main Results:
- cDNA AK057716 represents an incompletely spliced transcript, while CARD19 is the correctly spliced isoform of C9orf89.
- Endogenous CARD19 is expressed in T cells and localizes to mitochondria.
- Overexpression of BinCARD-1 or CARD19 inhibited NF-κB and promoted Bcl10 degradation.
- Loss of endogenous CARD19 had minimal impact on TCR-induced NF-κB activation, Malt1 activity, or Bcl10 degradation.
Conclusions:
- The primary translated product of C9orf89 is the mitochondrial protein CARD19.
- CARD19 does not play a significant role in TCR-dependent, Bcl10-mediated signal transduction to Malt1 or NF-κB.
Abstract:
After T cell receptor (TCR) engagement, the CARD11-Bcl10-Malt1 (CBM) complex oligomerizes to transduce NF-κB activating signals. Bcl10 is then degraded to limit NF-κB activation. The cDNA AK057716 (BinCARD-1) was reported to encode a novel CARD protein that interacts with Bcl10 and modestly inhibits NF-κB activation. In a later study, a second isoform, BinCARD-2, was identified. Here, we report that the cDNA AK057716 (BinCARD-1) is an incompletely spliced derivative of the gene product of C9orf89, whereas CARD19 (BinCARD-2) represents the properly spliced isoform, with conservation across diverse species. Immunoblotting revealed expression of CARD19 in T cells, but no evidence of BinCARD-1 expression, and microscopy demonstrated that endogenous CARD19 localizes to mitochondria. Although we confirmed that both BinCARD-1 and CARD19 can inhibit NF-κB activation and promote Bcl10 degradation when transiently overexpressed in HEK293T cells, loss of endogenous CARD19 expression had little effect on Bcl10-dependent NF-κB activation, activation of Malt1 protease function, or Bcl10 degradation after TCR engagement in primary murine CD8 T cells. Together, these data indicate that the only detectable translated product of C9orf89 is the mitochondrial protein CARD19, which does not play a discernible role in TCR-dependent, Bcl10-mediated signal transduction to Malt1 or NF-κB.
Related Concept Videos
02:26NF-κB-dependent Signaling Pathway
NF-κB-dependent Signaling Mechanism
The...
01:39Mitochondrial Protein Sorting
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:39Mitochondrial Precursor Proteins
Most of the mitochondrial...
01:34Protein Transport into the Inner Mitochondrial Membrane
Transport of mitochondrial precursors across the TIM23 channel is driven by...
01:22T Cell Activation and Clonal Selection
Naive T cells that have not yet encountered an antigen express two primary CD...
01:19Translocation of Proteins into the Mitochondria
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...