NANS

NANS encodes N-acetylneuraminic acid (sialic acid) synthase, the enzyme that catalyzes de novo synthesis of NeuNAc required for glycoprotein sialylation; biallelic loss-of-function mutations reduce its enzymatic activity and block incorporation of sialic acid precursors into sialylated glycoproteins, establishing it as essential for sialic acid biosynthesis and, in vivo, for normal development (PMID:27213289). Metabolically, NANS operates downstream of GFPT1 in the hexosamine biosynthetic pathway, where it specifically mediates the sialic acid synthesis branch, and its loss restrains tumor growth in c-Myc-driven hepatocellular carcinoma (PMID:40280277). Beyond this metabolic role, NANS has a non-catalytic function in which it physically associates with TAK1 to restrain NF-κB signaling; under ferroptotic stress CDK1 phosphorylates NANS at S275 to drive its dissociation from TAK1, and UBE2N-mediated ubiquitination at K246 triggers NANS degradation, releasing TAK1-NF-κB signaling to upregulate the ferroptosis inhibitor FTH1 and confer ferroptosis resistance and metastasis in colorectal cancer (PMID:40349344).

1. 2016 High

   Established that NANS is the enzyme responsible for de novo sialic acid synthesis and that its loss disrupts glycoprotein sialylation, defining its core metabolic function and a developmental disease link.

   Evidence Patient fibroblast enzymatic activity and sialic acid precursor incorporation assays, with zebrafish nansa knockdown partially rescued by exogenous sialic acid

   PMID:27213289

   Open questions at the time

   • Structural basis of catalysis not resolved in this corpus
   • Tissue-specific consequences of impaired sialylation beyond development not detailed
2. 2025 Medium

   Placed NANS within the hexosamine biosynthetic pathway as the dedicated sialic acid branch enzyme downstream of GFPT1 and tied its activity to oncogenic c-Myc-driven tumor growth.

   Evidence RNA-seq, metabolomics, NANS knockout in a murine c-Myc HCC model with tumor growth and survival readouts and luciferase confirmation of c-Myc regulation of GFPT1

   PMID:40280277

   Open questions at the time

   • Single-lab study not independently replicated
   • Whether the tumor-suppressive effect of knockout reflects loss of sialylation specifically versus broader metabolic perturbation is unresolved
3. 2025 Medium

   Revealed a non-metabolic role for NANS as a TAK1-binding suppressor of NF-κB signaling, controlled by CDK1 phosphorylation and UBE2N ubiquitination that license its degradation during ferroptotic stress.

   Evidence CRISPR-Cas9 ferroptosis screen, S275 phosphorylation mapping, NANS-TAK1 Co-IP, K246 ubiquitination assay, NF-κB and FTH1 readouts in colorectal cancer cells

   PMID:40349344

   Open questions at the time

   • Single-lab study with orthogonal assays but no independent replication
   • Whether the catalytic and TAK1-binding functions are mechanistically separable is not established
   • Reciprocal validation and structural basis of the NANS-TAK1 interaction not provided

• How the metabolic (sialic acid synthase) and non-metabolic (TAK1-binding) functions of NANS are integrated, and whether they are coupled or independent, remains unresolved.
• No structural model linking catalytic and protein-binding surfaces
• Physiological contexts where each function dominates are undefined