Xbp1 Knockout AC16 Cell Line

The Xbp1 Knockout AC16 Cell Line is a CRISPR/Cas9-edited knockout cell line generated from the AC16 human ventricular cardiomyocyte cell line, engineered to disrupt the Xbp1 gene. XBP1 encodes a transcription factor essential for the unfolded protein response (UPR), and its targeted disruption creates a robust loss-of-function model for investigating ER stress signaling in a cardiac context. This cell line allows researchers to interrogate XBP1-dependent transcriptional programs without confounding residual protein activity, making it suitable for pathway dissection and small-molecule screening.

The AC16 parental line is an SV40 T antigen-immortalized human ventricular cardiomyocyte cell line that retains hallmark characteristics of primary cardiomyocytes, including expression of cardiac-specific markers and a functional contractile apparatus. It is widely employed as an in vitro model to study human cardiac biology, encompassing hypertrophy, electrophysiology, and stress responses. The immortalized phenotype facilitates genetic manipulation and sustained culture, establishing AC16 as an optimal host for generating stable knockout derivatives for mechanistic and translational cardiovascular research.

XBP1 operates as a pivotal transcriptional effector of the adaptive UPR, activated by IRE1?? (ERN1)-mediated unconventional splicing upon ER stress. Spliced XBP1s directly induces a suite of target genes encoding ER chaperones such as BiP (HSPA5) and ER-associated degradation (ERAD) components like EDEM1 to enhance protein folding capacity and clearance of misfolded proteins. XBP1s also promotes lipid biosynthesis and autophagy to ensure ER homeostasis. Unspliced XBP1u can act as a negative regulator, while XBP1 functionally integrates with the ATF6 and PERK branches and coactivators p300/CBP and TFIIH to orchestrate the UPR network. Disruption of this IRE1??-XBP1 axis impairs adaptive responses and sensitizes cells to ER stress-induced apoptosis.

In AC16 cardiomyocytes, ablation of XBP1 is particularly relevant for modeling ER stress-associated cardiomyopathies and heart failure, given the high secretory demand and well-developed ER of cardiac cells. Loss of XBP1 disrupts the adaptive UPR, leading to accumulation of misfolded proteins, impaired ERAD, and activation of the pro-apoptotic CHOP (DDIT3) pathway. Consequently, the Xbp1 Knockout AC16 Cell Line serves as a critical tool to dissect the molecular mechanisms linking UPR deficiency to cardiac dysfunction and to evaluate pharmacological modulators of IRE1??-XBP1 signaling for therapeutic intervention.

This knockout model supports diverse experimental workflows, including ER stress induction with tunicamycin or thapsigargin followed by Western blot or RT-qPCR analysis of UPR markers, apoptosis assays (e.g., caspase-3 activity) to assess cell death susceptibility, and luciferase reporter assays to quantify XBP1s activity. Transcriptomic profiling via RNA-seq enables mapping of XBP1-dependent gene networks in cardiomyocytes. These applications empower rigorous investigation of IRE1??-XBP1 signaling in heart disease and facilitate screening for agents that restore ER homeostasis. For additional information, please contact Ascent Research to discuss your specific experimental needs.