POTEE

POTEE is a cytoplasmic oncogenic effector protein that promotes tumor cell proliferation, invasion, and metastasis across multiple cancer types by coupling to small-GTPase and growth-signaling pathways (PMID:32142855, PMID:38098337). A central activity is activation of the Rho-family GTPases Rac1 and Cdc42: in colorectal carcinoma POTEE elevates Rac1/Cdc42 activity to drive migration, invasion, and epithelial-mesenchymal transition (PMID:32142855), and in breast cancer it co-localizes with SUMOylated Rac1 (Rac1-SUMO1) at invadopodia where it recruits the TRIO guanine-nucleotide exchange factor to locally activate Rac1, driving invadopodium formation and metastasis (PMID:38098337). POTEE additionally engages mitogenic signaling through the SPHK1/p65 axis to promote cell-cycle progression and suppress apoptosis (PMID:31723122) and through the PI3K/Akt/GSK-3β/β-catenin pathway to support proliferation (PMID:32589786). In macrophages it scaffolds mTOR and RICTOR to assemble and activate mTORC2, which activates AKT and PKC-α to enhance invasion, an interaction co-opted by HIV-1 Nef (PMID:30420269, PMID:30391463). POTEE is also required for NMT1-mediated N-myristoylation of a defined set of substrate proteins (PMID:34136404) and sustains mitochondrial oxidative phosphorylation, with its protein levels controlled by TRIM33-mediated ubiquitin-proteasomal degradation directed by the lncRNA LINC00667 (PMID:40834976) and negatively regulated by MARK1 (PMID:39534429).

1. 2018 Medium

   Established that POTEE acts as a scaffold linking to growth/survival signaling by physically assembling the mTORC2 machinery, answering how POTEE could influence invasion at the molecular level.

   Evidence Co-immunoprecipitation of POTEE with mTOR/RICTOR/Rad51 plus siRNA knockdown with survival and invasion assays in macrophages and TAMs; independently, pull-down/MALDI-TOF/two-hybrid showing HIV-1 Nef bridges POTEE to mTOR/RICTOR to activate AKT and PKC-α

   PMID:30391463 PMID:30420269

   Open questions at the time

   • Direct vs. indirect nature of the POTEE–mTOR/RICTOR contact not resolved
   • Mapping of interaction domains absent
   • Findings confined to macrophage/TAM context
2. 2019 Medium

   Linked POTEE to a defined proliferative signaling axis, showing it drives growth and blocks apoptosis through SPHK1-dependent p65 activation.

   Evidence Microarray, gain/loss-of-function, western blotting, and xenograft tumor model in colorectal cancer

   PMID:31723122

   Open questions at the time

   • Mechanism by which POTEE raises SPHK1 protein levels unknown
   • No direct biochemical interaction demonstrated
3. 2020 Medium

   Defined POTEE's core motility function as activation of Rho-family GTPases and engagement of PI3K/Akt signaling, connecting it to invasion, EMT, and proliferation.

   Evidence Cytoplasmic localization by IHC, knockdown/overexpression with Rac1/Cdc42 activity assays and migration/invasion in CRC; siRNA knockdown plus GSK-3β inhibitor rescue and pathway western blotting in pancreatic cancer

   PMID:32142855 PMID:32589786

   Open questions at the time

   • How POTEE activates Rac1/Cdc42 not yet mechanistically defined
   • Direct vs. indirect engagement of PI3K/Akt pathway unresolved
4. 2021 Medium

   Revealed a role for POTEE in protein lipidation, showing it is required for NMT1-mediated N-myristoylation of specific substrate classes that are then differentially stabilized.

   Evidence Click-chemistry N-myristoylation assay, iTRAQ proteomics, liver conditional NMT1 knockout mouse, and PRM

   PMID:34136404

   Open questions at the time

   • Biochemical role of POTEE in the NMT1 reaction not defined
   • Whether POTEE is itself myristoylated unaddressed
5. 2023 Medium

   Resolved the molecular mechanism of POTEE-driven invasion, identifying it as a Rac1-SUMO1 effector that recruits TRIO-GEF to locally activate Rac1 at invadopodia.

   Evidence Co-localization, invadopodium formation and TRIO-GEF recruitment assays, with in vitro and in vivo proliferation/metastasis assays in breast cancer

   PMID:38098337

   Open questions at the time

   • Binding interface between POTEE and Rac1-SUMO1 not mapped
   • Mechanism of TRIO-GEF recruitment unknown
6. 2024 Low

   Identified an upstream negative regulator, MARK1, that binds POTEE and suppresses its expression to limit proliferation in drug-resistant cells.

   Evidence Luciferase reporter binding assay, qRT-PCR, and overexpression/rescue in sorafenib-resistant hepatocellular carcinoma cells

   PMID:39534429

   Open questions at the time

   • Direct physical interaction not confirmed by biochemical methods
   • Mechanism of MARK1-mediated POTEE suppression undefined
   • Single-lab, single model system
7. 2025 Medium

   Defined how POTEE protein abundance is post-translationally controlled and linked it to a metabolic output, showing LINC00667 directs TRIM33-mediated degradation of POTEE that regulates mitochondrial OXPHOS.

   Evidence CHIRP and RIP assays, cycloheximide chase, MG132 proteasome rescue, and OXPHOS complex western blotting with knockdown/overexpression

   PMID:40834976

   Open questions at the time

   • Site of TRIM33-mediated ubiquitination on POTEE unmapped
   • Mechanism linking POTEE to OXPHOS complex expression unknown

• How POTEE physically links to its many effectors (Rac1, mTORC2, SPHK1, NMT1) through defined structural domains, and whether these activities reflect one unified scaffold function or distinct context-specific roles, remains unresolved.
• No structural model or domain mapping for any interaction
• No reconstitution of POTEE-dependent Rac1 or NMT1 activation in vitro
• Unclear whether cancer-testis antigen expression confers a normal physiological function