PGM5

PGM5 is a phosphoglucomutase-family gene first identified as a widely expressed paralog of PGM1 mapping to the centromeric region of chromosome 9 (PMID:8586438). At the functional level, PGM5 promotes conversion of glucose-1-phosphate to glucose-6-phosphate and, through this modulation of aerobic glycolysis, restrains breast cancer cell proliferation and migration; its expression is post-transcriptionally suppressed by miR-1224-3p, which directly targets the PGM5 3'-UTR to relieve this glycolytic brake and thereby promote tumor cell growth and motility (PMID:33986801). Beyond these findings and a low-confidence link to ZIC4-dependent transcriptional control, no further mechanistic detail has been characterized in the available corpus.

1. 1995 Medium

   Established PGM5 as a distinct expressed gene in the phosphoglucomutase family, defining its genomic location and inferred biochemical class before any functional role was known.

   Evidence Molecular cloning with RT-PCR/Northern expression analysis and chromosomal mapping by FISH and somatic cell hybrids

   PMID:8586438

   Open questions at the time

   • Enzymatic activity was inferred from PGM1 homology, not reconstituted in vitro
   • No cellular or physiological function assigned
   • No protein-level characterization
2. 2021 Medium

   Connected PGM5 to a metabolic and tumor-suppressive role by linking its glycolytic function to control of cancer cell proliferation/migration and identifying miR-1224-3p as a direct upstream repressor.

   Evidence Luciferase 3'-UTR reporter, glycolysis assays, and proliferation/migration assays with PGM5 knockdown and overexpression in breast cancer cells

   PMID:33986801

   Open questions at the time

   • G1P-to-G6P catalysis attributed by family membership, not direct in vitro reconstitution of PGM5 enzyme activity
   • Single lab; not extended beyond breast cancer context
   • Mechanistic link between glycolytic flux and proliferation/migration not dissected
3. 2023 Low

   Placed PGM5 downstream of a transcriptional and epigenetic regulatory axis, with ZIC4 and gene-body DNA methylation modulating its expression in a brain organoid model.

   Evidence siRNA silencing of Zic4 with PGM5 protein readout, RRBS-Seq methylation profiling, and computational promoter motif analysis in mouse brain organoids

   PMID:38074999

   Open questions at the time

   • No direct ChIP confirmation of ZIC4 binding the Pgm5 promoter; binding inferred from computational motif analysis and single knockdown
   • Functional consequence of PGM5 changes in neural/organoid context not established
   • Relationship between this transcriptional axis and the metabolic role is unknown

• Whether PGM5 itself catalyzes the G1P-to-G6P reaction and how its metabolic activity is integrated into broader physiology remain unresolved.
• No in vitro demonstration of PGM5 catalytic activity
• No structural model or substrate kinetics
• Physiological role outside cancer cell lines uncharacterized