JPH1 Knockout NCI-H1975 Polyclonal Cells constitute a CRISPR/Cas9-edited polyclonal knockout cell population designed for the study of ER-plasma membrane (PM) junctions and calcium signaling in lung adenocarcinoma. This heterogeneous pool of NCI-H1975 cells carries a targeted disruption of the JPH1 gene, generating a loss-of-function model without the selection of a single-cell clone.
The parental NCI-H1975 line is a human non-small cell lung adenocarcinoma epithelial cell model harboring the activating EGFR L858R mutation and the acquired T790M resistance mutation. These genetic alterations drive constitutive oncogenic signaling and confer resistance to first- and second-generation EGFR tyrosine kinase inhibitors, making the cell line an essential system for investigating adaptive mechanisms in lung cancer, including calcium-dependent pathways that may modulate drug sensitivity.
JPH1 encodes junctophilin-1, a structural protein that tethers the endoplasmic reticulum (ER) to the plasma membrane at junctional membrane complexes. JPH1 interacts with phosphatidylinositol 4,5-bisphosphate (PIP2) at the PM and functionally couples ryanodine receptor 2 (RYR2) and L-type calcium channels (CACNA1C) to the store-operated calcium entry apparatus. It operates downstream of calcium influx and calcineurin/NFAT signaling and is transcriptionally regulated by MEF2 factors. JPH1-organized nanodomains facilitate activation of STIM1 and ORAI1 channels, sustaining calcium entry that drives calmodulin-dependent kinases such as CaMKII and the transcription factor NFAT. Knockout of JPH1 disrupts ER-PM apposition, impairing STIM1 puncta formation and consequently attenuating store-operated calcium entry and NFAT-dependent gene expression.
In NCI-H1975 cells, which exhibit altered calcium handling as a hallmark of transformed and drug-resistant states, disrupting JPH1 allows dissection of ER-PM junction-specific contributions to tumor cell proliferation, migration, and survival. This knockout model enables interrogation of how calcium microdomains intersect with EGFR-driven MAPK and PI3K pathways, potentially revealing vulnerabilities that can be exploited in combination therapies.
Researchers can employ this polyclonal knockout population to investigate the role of junctional membrane complexes in lung adenocarcinoma progression, evaluate NFAT transcriptional activity via luciferase reporter assays, and screen for pharmacological modulators of ER-PM junctions. Standard validation techniques include Western blotting for JPH1, RT-qPCR for JPH1 mRNA, and immunofluorescence microscopy to assess STIM1 cluster formation. Functional studies benefit from calcium imaging with Fura-2 or GCaMP and store-operated calcium entry assays, while cell proliferation, migration, and invasion assays quantify phenotypic effects. For further details or ordering information, contact Ascent Research.
