Related Experiment Video
Updated: Oct 7, 2026
Caspase-3 Activity in the Rat Amygdala Measured by Spectrofluorometry After Myocardial Infarction
Published on: January 12, 2016
Molecular cloning and characterization of a novel caspase-3 variant that attenuates apoptosis induced by proteasome
1Department of Neuroscience Therapeutics, Pfizer Global Research & Development, Ann Arbor Laboratories, 2800 Plymouth Road, Ann Arbor, Michigan 48105, USA.
Abstract:
Caspase-3 plays an important role in programmed cell death as an execution-phase caspase in degradation of many substrate proteins. We identified a naturally occurring short caspase-3 variant (caspase-3s) from a human carcinoma cell line that is resulted from alternative mRNA splicing. Analysis of nucleotide sequence reveals a deletion of the exon 6 in this variant that resulted in an altered reading frame in the C-terminus, leading to an altered amino acid sequence and a truncated protein. Caspase-3s shares the same amino acid sequence as caspase-3 in the N-terminus containing the prodomain and the majority of the large subunit. The variant is 95 amino acid residues shorter at the C-terminus and is missing the conserved QACRG sequence in the catalytic site. Caspase-3 and caspase-3s are coexpressed in all human tissues examined. Several cancer cell lines also show coexpression of caspase-3 and caspase-3s, both at the mRNA and protein levels. Overexpression of caspase-3s in 293 cells is more resistant to apoptosis induced by proteasome inhibition. Furthermore, we identified that proteasome inhibition stabilized the level of caspase-3s.
Insights
A newly identified caspase-3 variant (caspase-3s), generated by alternative splicing, is coexpressed with caspase-3 in human tissues. This variant confers resistance to apoptosis induced by proteasome inhibition.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Caspase-3 is a key executioner caspase in programmed cell death, crucial for protein degradation.
- Alternative mRNA splicing can generate protein variants with altered functions.
Purpose of the Study:
- To identify and characterize a naturally occurring short variant of caspase-3.
- To investigate the functional implications of this caspase-3 variant in apoptosis and its expression patterns.
Main Methods:
- Nucleotide sequence analysis to identify exon deletions and altered reading frames.
- Co-expression analysis at both mRNA and protein levels in various human tissues and cancer cell lines.
- Overexpression studies in 293 cells to assess apoptosis resistance and protein stability under proteasome inhibition.
Main Results:
- A short caspase-3 variant (caspase-3s) was identified, resulting from alternative splicing with a deletion in exon 6, leading to a truncated protein lacking the catalytic QACRG motif.
- Caspase-3 and caspase-3s are coexpressed across all examined human tissues and in several cancer cell lines.
- Overexpression of caspase-3s rendered cells more resistant to proteasome inhibitor-induced apoptosis, and proteasome inhibition stabilized caspase-3s levels.
Conclusions:
- Alternative splicing produces a functional caspase-3 variant (caspase-3s) with altered apoptotic activity.
- The coexpression of caspase-3 and caspase-3s suggests a complex regulatory role in programmed cell death.
- Caspase-3s may play a role in cancer cell survival by conferring resistance to apoptosis, particularly under conditions of proteasome inhibition.
