GOLT1B

GOLT1B is a conserved cis-Golgi membrane protein that controls the trafficking and surface delivery of specific cargo to regulate signaling outputs governing cell growth, proliferation, and immune evasion (PMID:33370778, PMID:34059062). Genetics in the C. elegans ortholog eas-1 establish its core mechanism: cis-Golgi GOLT1B drives shuttling of the E3 ubiquitin ligase RNF145 from the cis-Golgi to the trans-Golgi network, releasing inhibition of nuclear SREBP activation and thereby controlling fatty acid synthesis and arresting glial cell growth (PMID:33370778). In human cancer cells GOLT1B promotes plasma-membrane translocation of DVL2 to activate Wnt/β-catenin signaling and drive epithelial-mesenchymal transition (PMID:34059062), and it binds and increases surface localization of the checkpoint ligand PD-L2 to induce T cell apoptosis (PMID:34059062). GOLT1B also interacts with TBK1 to activate NF-κB-dependent transcription, enhancing cancer cell viability and migration (PMID:39113410). Its ER-Golgi trafficking function is co-opted during the unfolded protein response, where GOLT1B is induced and is required for efficient hepatitis C virus replication (PMID:35055994).

1. 2020 High

   The fundamental molecular role of GOLT1B was unknown; ortholog genetics established it as a cis-Golgi protein that gates intra-Golgi shuttling of an E3 ligase to control SREBP-driven lipid synthesis and cell growth.

   Evidence C. elegans loss-of-function genetics, epistasis, live imaging of cis- vs trans-Golgi localization, and fatty acid supplementation rescue

   PMID:33370778

   Open questions at the time

   • Whether the human GOLT1B–RNF145–SREBP axis operates identically in mammalian cells is not demonstrated in this study
   • Direct biochemical mechanism by which GOLT1B drives RNF145 shuttling is not resolved
   • No structural model of GOLT1B cargo engagement
2. 2021 Medium

   Whether GOLT1B influences oncogenic signaling was unknown; it was shown to traffic DVL2 to the plasma membrane, activating Wnt/β-catenin and EMT, linking Golgi transport to colorectal cancer progression.

   Evidence Overexpression/knockdown in CRC cell lines with subcellular fractionation, confocal imaging, β-catenin pathway western blots, and xenograft model

   PMID:34059062

   Open questions at the time

   • Whether GOLT1B directly binds DVL2 or acts indirectly is not established
   • Single lab; mechanism of cargo selectivity unknown
3. 2021 Medium

   It was unknown whether GOLT1B contributes to tumor immune evasion; it was found to interact with PD-L2 and elevate its surface levels, driving T cell apoptosis.

   Evidence Co-immunoprecipitation, flow cytometry for membrane PD-L2, and Jurkat T cell co-culture apoptosis assay

   PMID:34059062

   Open questions at the time

   • Co-IP without reciprocal validation or mapping of interaction interface
   • In vivo relevance to immune checkpoint suppression not tested
4. 2022 Medium

   Whether GOLT1B participates in viral infection was unknown; its induction during ER stress and requirement for HCV replication tied its ER-Golgi trafficking role to the viral life cycle.

   Evidence RNAseq of laser-microdissected HCV-infected hepatocytes, siRNA knockdown with HCV replication readout, and UPR induction assays

   PMID:35055994

   Open questions at the time

   • Specific trafficking step or viral cargo dependent on GOLT1B not identified
   • Mechanistic link between UPR induction and replication requirement unresolved
5. 2025 Medium

   A further signaling input was unknown; GOLT1B was shown to interact with TBK1 and activate NF-κB transcription, promoting cervical carcinoma viability and migration.

   Evidence Co-IP for GOLT1B–TBK1 interaction, NF-κB dual luciferase reporter, functional viability/migration assays, and in vivo tumor model

   PMID:39113410

   Open questions at the time

   • Whether GOLT1B regulates TBK1 kinase activity or simply scaffolds it is unknown
   • Single lab; interaction not independently confirmed

• How GOLT1B selects among its diverse reported cargo (DVL2, PD-L2, RNF145) and whether a single Golgi-shuttling mechanism underlies all its signaling roles remains unresolved.
• No unifying biochemical model connecting cargo trafficking to the multiple downstream pathways
• No structural characterization of GOLT1B cargo recognition
• Conservation of the RNF145/SREBP axis in human cells not demonstrated