COPG1

COPG1 is a subunit of the COPI coatomer complex that supports Golgi-dependent vesicular trafficking and the integrity of the early secretory pathway [PMID:bio_10.1101_2025.08.21.25332476, PMID:bio_10.1101_2024.10.12.618008]. In hepatocytes, COPG1 is required for HDL holoparticle uptake, selective HDL lipid uptake, and apoA-I secretion; its depletion lowers cell-surface abundance of the scavenger receptor SR-BI (via interference with SR-BI glycosylation) and reduces APOA1 expression, while raising surface ABCA1 and ABCA1-mediated cholesterol efflux [PMID:bio_10.1101_2025.08.21.25332476]. The same COPI trafficking machinery is exploited for efficient secretion of the flaviviral non-structural protein NS1, since COPG1 knockdown reduces NS1 secretion from dengue- and West Nile virus-infected cells without affecting infectious virus egress [PMID:bio_10.1101_2024.10.12.618008]. In hepatocellular carcinoma cells, loss of COPG1 disrupts Golgi morphology and triggers ER stress, elevates reactive oxygen species, and suppresses PI3K-AKT signaling, impairing malignant phenotypes and sensitizing cells to sorafenib and doxorubicin (PMID:41751842). Beyond these trafficking and cancer-cell phenotypes, no further molecular detail of COPG1 has been characterized in the available corpus.

1. 2024 Medium

   Established that the COPI subunit COPG1 is selectively required for cellular secretion of flaviviral NS1, distinguishing host trafficking needs for protein secretion from those for virus egress.

   Evidence Membrane-trafficking siRNA screen and targeted knockdown in DENV- and WNV/KUNV-infected cells with NS1 secretion assays, plus expression of COPI variants and chemical inhibition (preprint)

   PMID:bio_10.1101_2024.10.12.618008

   Open questions at the time

   • Direct interaction between COPG1 and NS1 not demonstrated
   • Step in the secretory pathway where COPI acts on NS1 not resolved
   • Preprint not yet peer-reviewed
2. 2025 Medium

   Identified COPG1 as a hepatocyte trafficking factor controlling HDL uptake and apoA-I output through regulation of SR-BI and ABCA1 surface abundance, linking COPI function to lipoprotein metabolism.

   Evidence Genome-wide RNAi screen for fluorescent HDL uptake in Huh-7 cells with siRNA validation, surface receptor flow cytometry, apoA-I secretion and cholesterol efflux assays (preprint)

   PMID:bio_10.1101_2025.08.21.25332476

   Open questions at the time

   • Mechanism by which COPG1 loss alters SR-BI glycosylation not directly shown
   • Opposing effects on SR-BI versus ABCA1 not mechanistically explained
   • Preprint not yet peer-reviewed
3. 2026 Medium

   Connected COPG1-dependent Golgi/ER homeostasis to cancer cell survival, showing its loss triggers ER stress, ROS, and PI3K-AKT suppression that sensitizes tumor cells to chemotherapy.

   Evidence COPG1 knockdown in HCC cell lines with in vivo tumorigenicity, Golgi and ER stress markers, ROS, AKT signaling, and drug sensitivity assays

   PMID:41751842

   Open questions at the time

   • Causal ordering of Golgi disruption, ER stress, ROS, and AKT suppression not resolved
   • Direct molecular targets connecting COPG1 to PI3K-AKT not identified
   • Single lab

• How COPG1, as a coatomer subunit, achieves cargo selectivity across these distinct contexts (lipoprotein receptors, viral NS1, pro-survival signaling components) remains unresolved.
• No structural or biochemical map of COPG1 cargo recognition
• No direct interactome reported in the corpus
• Tissue-specific functions beyond hepatocytes and cancer cells uncharacterized