Description

The PSMB5 Knockout HeLa Cell Line is a CRISPR/Cas9-edited knockout cell line that disrupts the human PSMB5 gene, creating a stable loss-of-function model in a widely used cancer cell host. This knockout system eliminates the ??5 catalytic subunit of the 20S proteasome, enabling precise dissection of ubiquitin-proteasome pathway functions.

HeLa cells originate from a cervical adenocarcinoma and are positive for human papillomavirus type 18 (HPV-18), providing an epithelial cancer background relevant for proteasome research. These immortalized cells are established in numerous cancer studies and facilitate analysis of proteasome-dependent oncogenic processes.

The PSMB5 gene encodes the ??5 subunit of the 20S proteasome core, responsible for its chymotrypsin-like protease activity. This catalytic subunit is central to ubiquitin-dependent protein degradation, processing ubiquitinated substrates into peptides. PSMB5 expression is regulated by transcription factors NF-??B, Nrf2, and interferon-gamma, and by assembly chaperones. Key downstream targets include Cyclin D1, p53, and I??B??, connecting proteasome activity to cell cycle regulation and apoptosis. The ??5 subunit associates with PSMA1?C7, PSMB6, and PSMB7, and is assembled with POMP and UMP1, forming the 20S core that interacts with the 19S regulatory particle. Functional proteasomes generate peptides presented on MHC class I molecules, dependent on TAP transporter, highlighting the immune role of PSMB5.

In the HeLa cell context, PSMB5 knockout abolishes chymotrypsin-like proteasome activity, leading to accumulation of polyubiquitinated proteins and impaired degradation of Cyclin D1, p53, and I??B??. This results in disrupted cell cycle progression and apoptosis signaling, while diminished MHC class I antigen presentation compromises immune recognition. The HPV-18 oncoprotein background adds relevance for investigating proteasome inhibition in cervical carcinogenesis.

The PSMB5 Knockout HeLa Cell Line is applicable for proteasome inhibition studies, cancer drug resistance research, and analysis of antigen processing and immunoproteasome function. Assays include Western blotting for PSMB5 and ubiquitinated proteins, chymotrypsin-like activity measurement, cell viability (MTT/XTT), apoptosis (Annexin V), MHC class I surface expression by flow cytometry, RT-qPCR for proteasomal genes, and drug sensitivity tests (e.g., bortezomib). This model thus supports pathway dissection and therapeutic screening. For further technical information, please contact Ascent Research.