RASSF7

RASSF7 is a centrosome-associated RAS-family effector that couples microtubule organization to mitotic progression and stress signaling (PMID:18272789, PMID:20629633). Localization to the centrosome is microtubule-dependent and is conferred specifically by its coiled-coil domain, which is necessary and sufficient for targeting; disrupting this organization through C-terminal truncation drives γ-tubulin accumulation, centrosome amplification, and cell death (PMID:26569555). At the centrosome RASSF7 regulates microtubule dynamics and is required for Aurora B activation, chromosomal congression, and mitotic spindle formation, with loss of function causing spindle failure, mitotic arrest, and apoptosis (PMID:18272789, PMID:20629633). As a RAS effector, RASSF7 binds GTP-loaded N-Ras through its RA domain and engages MKK7 to suppress pro-apoptotic JNK signaling during acute stress, while prolonged stress triggers its ubiquitin-proteasome-mediated degradation to release the pathway (PMID:21278800). It also positively feeds MEK/ERK signaling—acting in association with DISC1 to promote astrogenesis through nuclear translocation of pERK—and activates MEK1/2-ERK1/2 to drive G1-S transition (PMID:27287808, PMID:29729697). Through its RA and leucine-zipper domains RASSF7 antagonizes c-Myc, promoting Cullin4B-mediated polyubiquitination and degradation, competing with MAX for heterodimerization, and reducing c-Myc promoter occupancy to inhibit oncogenic transformation (PMID:30139745).

1. 1994 Medium

   Before any function was known, the genomic context of RASSF7 was defined, placing it immediately upstream of and divergently transcribed from HRAS1, anchoring its later identification as a RAS-pathway gene.

   Evidence Pulsed-field gel electrophoresis, Southern blot, and P1 clone physical mapping of human chromosome 11p15.5

   PMID:7710782

   Open questions at the time

   • Establishes only chromosomal locus and gene order, no functional or biochemical role
   • Physical proximity to HRAS1 does not establish a regulatory or effector relationship
2. 2008 High

   The first functional study established RASSF7 as a centrosomal protein essential for mitotic spindle formation, answering whether it has a role in cell division.

   Evidence Morpholino knockdown and immunofluorescence in Xenopus embryos with microtubule-dependency assay

   PMID:18272789

   Open questions at the time

   • Mechanism by which RASSF7 promotes spindle assembly not defined
   • Molecular partners at the centrosome not identified
3. 2010 High

   The mitotic role was extended to human cells and linked to specific machinery, showing RASSF7 regulates microtubule dynamics and is required for Aurora B activation and chromosomal congression.

   Evidence siRNA knockdown, immunofluorescence, microtubule-regrowth assays, and kinase activity assays in human cell lines

   PMID:20629633

   Open questions at the time

   • Direct link between RASSF7 and Aurora B activation mechanism unresolved
   • Whether RASSF7 acts as a structural scaffold or signaling intermediate at the spindle unclear
4. 2010 High

   RASSF7 was defined as a bona fide RAS effector that gates stress-induced apoptosis, answering how it connects RAS to cell death decisions.

   Evidence Reciprocal Co-IP, RA-domain mutagenesis, kinase assays, and proteasome inhibitor experiments

   PMID:21278800

   Open questions at the time

   • Ubiquitin ligase responsible for stress-induced RASSF7 degradation not identified
   • Mechanism by which RASSF7 uncouples MKK7 phosphorylation from JNK activation not structurally defined
5. 2015 Medium

   Domain dissection resolved which region targets RASSF7 to the centrosome, showing the coiled-coil domain is necessary and sufficient and that mislocalization causes centrosome defects.

   Evidence Truncation construct expression and quantitative centrosomal-marker immunofluorescence in Xenopus embryos

   PMID:26569555

   Open questions at the time

   • Centrosomal docking partner of the coiled-coil domain not identified
   • Single-lab Xenopus system; human cell confirmation of truncation phenotype absent
6. 2016 Medium

   A positive signaling arm was added, showing RASSF7 partners with DISC1 to activate RAS/MEK/ERK and drive astrogenesis, distinct from its apoptosis-suppressing role.

   Evidence Co-IP, in vivo/in vitro DISC1 perturbation, and rescue experiments in mouse embryonic brain

   PMID:27287808

   Open questions at the time

   • Whether RASSF7 directly engages MEK/ERK components or acts via N-Ras not resolved
   • Single-lab finding; reciprocal validation of the DISC1-RASSF7 association limited
7. 2018 High

   RASSF7 was shown to negatively regulate c-Myc through a trimodal mechanism, establishing a tumor-suppressive function opposed to its proliferative MEK/ERK role.

   Evidence Co-IP, RA/LZ domain mapping, ubiquitination assay, ChIP, and transformation assay in HEK293T and HeLa cells

   PMID:30139745

   Open questions at the time

   • How RASSF7 recruits Cullin4B to c-Myc not defined
   • Reconciliation of c-Myc-inhibitory versus proliferation-promoting activities in the same cell context not addressed
8. 2018 Medium

   A pro-proliferative function in hepatocellular carcinoma was demonstrated, showing RASSF7 drives G1-S transition via MEK1/2-ERK1/2 activation.

   Evidence Overexpression/knockdown in HCC cell lines with cell cycle, apoptosis, and phospho-MEK/ERK Western analyses

   PMID:29729697

   Open questions at the time

   • No direct binding assay linking RASSF7 to MEK1/2
   • Single-lab study; context-dependence relative to its c-Myc-inhibitory tumor-suppressor role unresolved

• How RASSF7's centrosomal/mitotic function, RAS-effector stress signaling, MEK/ERK-promoting activity, and c-Myc-inhibitory tumor-suppression are integrated within a single cell type remains unresolved.
• No unifying model reconciling pro-proliferative and tumor-suppressive activities
• Centrosomal docking partner and structural basis of coiled-coil targeting unknown
• Endogenous regulation switching RASSF7 between signaling modes not defined