Multiple PROTAC candidates in the global pipeline are rapidly advancing into clinical stages. Among them, Vepdegestrant (ARV-471), jointly developed by Arvinas and Pfizer, has been submitted to the U.S. FDA for new drug approval. If approved, it will become the world’s first marketed PROTAC degrader. This milestone marks a critical transition of targeted protein degradation from research validation to clinical application.
Amid this technological wave, E3 ubiquitin ligases have attracted significant attention as key degradation engines. CRBN (Cereblon) and VHL (Von Hippel–Lindau), due to their strong compatibility with PROTAC and molecular glue strategies, have become the two most widely used E3 targets, broadly applied in targeted degradation mechanism studies and drug screening. To meet the needs of scientific research and drug development, the cell biology division of Kyinno Biotechnology has developed CRBN KO and VHL KO cell lines based on these cutting-edge targets, providing precise and efficient experimental platforms for related studies.
CRBN (Cereblon) is the substrate recognition subunit of the E3 ubiquitin ligase complex CRL4^CRBN, which mediates ubiquitination of specific substrates and directs them to proteasomal degradation. CRBN-based molecular glues and PROTAC molecules can induce targeted degradation of disease-related proteins, making it one of the key research focuses in the targeted degradation field.
VHL (Von Hippel–Lindau) is another critical substrate recognition protein of E3 ubiquitin ligases. It forms a complex with Cullin-2, Elongin B/C, and others to recognize and promote ubiquitination and degradation of substrates such as hypoxia-inducible factor (HIF). VHL plays an essential role in regulating cellular oxygen-sensing pathways and is also one of the preferred E3 ligases in PROTAC design.
Currently, a wide range of PROTAC applications rely on CRBN and VHL as central E3 ligase hubs, making these two targets indispensable in the development of novel targeted degradation therapeutics.
Protein Ubiquitination and Degradation System
The ubiquitin–proteasome system (UPS) is the primary pathway for maintaining protein homeostasis in cells. Among its components, E3 ubiquitin ligases exhibit high substrate specificity. They transfer activated ubiquitin tags onto target proteins, marking them for recognition and degradation by the proteasome. CRBN and VHL are two commonly used substrate receptors in UPS-based targeted degradation strategies.
Targeted Protein Degradation Drug Strategy
By designing small-molecule ligands into bifunctional molecules that bind both the target protein and an E3 ligase (i.e., PROTACs), the target protein can be brought into proximity with the E3 ligase, forming a ternary complex within the cell. This promotes ubiquitination and subsequent degradation of the target protein. This strategy not only overcomes the limitations of traditional inhibitors on “undruggable” targets but also enables catalytic reuse of the degradation mechanism, achieving more efficient and sustained target intervention.
CRBN and VHL, due to their ability to bind diverse chemical ligands and their broad expression across commonly used cell models, have become the most typical E3 ligases selected in PROTAC design.
CRBN and VHL are not traditional oncogenes, but their roles in ubiquitination and degradation are closely associated with disease:
CRBN and molecular glue-mediated targeted degradation : Immunomodulatory imide drugs (IMiDs), such as lenalidomide and pomalidomide, bind to CRBN and influence the ubiquitination and degradation of key transcription factors, providing new therapeutic approaches for hematological malignancies and other diseases.
VHL and tumor signaling pathways : In addition to functioning as an E3 ligase, loss of VHL activity leads to persistent activation of the HIF signaling pathway, resulting in abnormal angiogenesis and cellular energy regulation. Related mutations have been shown to be closely associated with diseases such as renal cell carcinoma.
Therefore, in vitro cell models targeting CRBN and VHL are valuable not only for exploring fundamental biological mechanisms but also for evaluating the efficacy and mechanisms of targeted degradation drugs, making them essential platforms in early-stage drug development and pharmacological assessment.
CRBN-KO and VHL-KO Cell Lines from Kyinno Biotechnology
To address specific research needs in targeted degradation studies and drug screening, Kyinno Biotechnology has developed a series of CRBN and VHL gene knockout (KO) cell lines, covering representative tumor cell backgrounds. These models are suitable for in-depth investigation of E3 ligase functions, construction of degradation mechanism models, and screening and validation of PROTAC activity. Some products are listed below:
CRBN-KO Cell Lines
Partial validation data:
VHL-KO Cell Lines
These cell lines are constructed using gene editing technologies such as CRISPR/Cas9, with targeted knockout of CRBN or VHL genes. A comprehensive phenotypic validation system ensures their reliability, providing high-quality experimental models for mechanistic studies and drug screening.
