TVP23B

TVP23B is a trans-Golgi transmembrane protein that maintains the glycosylation capacity of the Golgi apparatus in intestinal epithelial cells, thereby supporting epithelial barrier function (PMID:37339972). It physically binds the Golgi protein YIPF6, and loss of either protein causes a common depletion of glycosylation enzymes from the colonocyte Golgi proteome, linking TVP23B to the maintenance of Golgi enzyme content (PMID:37339972). Through this activity TVP23B controls Paneth cell homeostasis and goblet cell glycosylation, such that its loss reduces antimicrobial peptides and produces a more penetrable mucus layer (PMID:37339972); it is specifically required to form the sterile, bacteria-free inner mucin layer that maintains the host–microbiota balance in vivo (PMID:37339972). Beyond the intestine, knockdown of TVP23B in retinal microvascular endothelial cells enhances migration and tube formation in an NF-κB-dependent manner, as these effects are reversed by the NF-κB inhibitor PDTC, placing TVP23B upstream of NF-κB signaling in these cells (PMID:25221423). The molecular basis by which a Golgi glycosylation regulator restrains NF-κB activation has not been characterized in the available corpus.

1. 2014 Medium

   Established the first cellular phenotype for TVP23B (FAM18B), showing it constrains endothelial migration and angiogenic behavior via NF-κB.

   Evidence siRNA knockdown in primary human retinal microvascular endothelial cells with migration, tube-formation, and viability assays plus pharmacological rescue using the NF-κB inhibitor PDTC

   PMID:25221423

   Open questions at the time

   • No molecular link drawn between the Golgi/transmembrane identity of TVP23B and NF-κB activation
   • Direct biochemical targets or signaling intermediates are not identified
   • Effect shown only in one endothelial cell type by knockdown without rescue by re-expression
2. 2023 Medium

   Defined TVP23B as a trans-Golgi protein required for intestinal barrier function and placed it within a Golgi glycosylation pathway through its partner YIPF6.

   Evidence ENU forward genetic screen identifying a colitis-susceptibility Tvp23b mutation, in vivo loss-of-function characterization of Paneth and goblet cells, co-immunoprecipitation of YIPF6, and Golgi proteomics of TVP23B- and YIPF6-deficient colonocytes

   PMID:37339972

   Open questions at the time

   • Mechanism by which TVP23B/YIPF6 retains or recruits glycosylation enzymes in the Golgi is not resolved
   • The interaction rests on co-immunoprecipitation without reciprocal or structural validation
   • Whether the endothelial NF-κB role and the intestinal glycosylation role share a common molecular mechanism is unaddressed
3. 2025 Low

   Extended TVP23B function to macrophages, indicating it supports a pro-fibrotic paracrine program relevant to ischemic cardiomyopathy.

   Evidence In vivo macrophage-specific siRNA knockdown via lipidoid nanoparticles in a mouse myocardial infarction model, with cardiac function and fibrosis as phenotypic readouts (preprint)

   PMID:40894159

   Open questions at the time

   • Preprint; no direct molecular mechanism established for TVP23B in macrophages
   • Downstream pro-fibrotic mediators are not identified
   • Cell-type-specific knockdown phenotype not corroborated by genetic deletion or rescue

• How TVP23B mechanistically maintains Golgi glycosylation enzyme content and how this connects to NF-κB signaling and macrophage pro-fibrotic programs remains unresolved.
• No biochemical mechanism linking TVP23B–YIPF6 binding to enzyme retention
• No unifying model across intestinal, endothelial, and macrophage contexts
• No structural information on TVP23B or its complex with YIPF6