GPBP1

GPBP1 is a nucleic acid-binding protein that contributes to genome maintenance and signal transduction across multiple cellular contexts (PMID:26156556, PMID:29669295). Its extended AT-hook (eAT-hook) motif functions as a binding domain that preferentially associates with RNA over DNA, binding RNA with approximately tenfold higher affinity, indicating a primarily RNA-directed engagement rather than the DNA binding implied by its original naming (PMID:26156556). Functionally, GPBP1 is required for normal homologous recombination: its loss reprograms expression of recombination genes and confers resistance to cisplatin and PARP inhibitors (PMID:29669295). In a separate context, GPBP1 physically interacts with RTN3 and operates within an IGF2-JAK2-STAT3 signaling axis that connects RTN3 loss in proximal tubular epithelial cells to dysregulated collagen biosynthesis and mitochondrial function (PMID:35596061). Beyond these roles, no unified mechanistic model linking the RNA-binding, recombination, and signaling activities has been characterized in the available corpus.

1. 2015 Medium

   Resolved the molecular nature of GPBP1's nucleic acid binding, showing its eAT-hook motif is a binding domain that prefers RNA over DNA — overturning the implication of its 'GC-rich promoter binding' name.

   Evidence Microscale thermophoresis and EMSA with recombinant eAT-hook peptides

   PMID:26156556

   Open questions at the time

   • Only the isolated peptide motif was tested, not full-length GPBP1
   • No specific physiological RNA target identified
   • Single lab, single study
2. 2018 Medium

   Placed GPBP1 in the DNA damage response by showing its loss alters homologous recombination genes and produces resistance to cisplatin and PARP inhibitors, defining a chemosensitivity phenotype.

   Evidence Quantitative chemical-genetic interaction map with shRNA knockdown in human mammary epithelial cells across 29 drugs

   PMID:29669295

   Open questions at the time

   • Mechanistic link from RNA binding to homologous recombination not established
   • Direct molecular role of GPBP1 in the HR machinery undefined
   • No structural or biochemical follow-up on how GPBP1 regulates HR genes
3. 2022 Medium

   Identified a physical partner (RTN3) and a signaling pathway (IGF2-JAK2-STAT3) for GPBP1, linking it to collagen biosynthesis and mitochondrial function in kidney epithelium.

   Evidence Co-IP in HEK293 and primary proximal tubular epithelial cells plus an RTN3-null mouse model

   PMID:35596061

   Open questions at the time

   • GPBP1-RTN3 interaction lacks orthogonal validation in the report
   • How GPBP1 mechanistically activates the IGF2-JAK2-STAT3 axis is unspecified
   • Connection between this signaling role and GPBP1's RNA-binding/HR functions is unknown
4. 2025 Low

   Positioned GPBP1 as a post-transcriptional target of miR-216a-5p whose suppression mediates anti-inflammatory and neuroprotective effects.

   Evidence miR-216a-5p overexpression in mesenchymal stem cells in a rat spinal cord injury model

   PMID:40708043

   Open questions at the time

   • Direct targeting claimed without a stated validation method such as luciferase reporter
   • No mechanistic dissection of GPBP1's role downstream of miR-216a-5p
   • Single study in one injury model

• It remains unknown how GPBP1's RNA-binding activity mechanistically connects to its roles in homologous recombination and IGF2-JAK2-STAT3 signaling, and whether these represent one unified function or context-specific activities.
• No physiological RNA substrate identified
• No structure of full-length GPBP1 or its complexes
• No mechanism connecting binding activity to downstream phenotypes