MVD

MVD encodes mevalonate diphosphate decarboxylase, which catalyzes the ATP-dependent decarboxylation of mevalonate diphosphate to isopentenyl diphosphate in the mevalonate/isoprenoid biosynthetic pathway, a function conserved from yeast to mammals (PMID:12073030). MVD physically interacts with mortalin (GRP75), and co-expression of MVD rescues mortalin-induced suppression of Ras and phospho-ERK2 levels, linking MVD to modulation of the Ras-Raf-MAPK proliferation pathway (PMID:12646231). Biallelic loss-of-function of MVD in keratinocytes—through germline heterozygous mutations combined with somatic second-hit events—drives clonal epidermal expansion causing porokeratosis, while MVD haploinsufficiency in a knock-in mouse model attenuates inflammatory skin responses and activates autophagy (PMID:30942823, PMID:31207227, PMID:37227548).

1. 2002 Medium

   Establishing that MVD encodes a bona fide mevalonate diphosphate decarboxylase: heterologous expression of C. albicans MVD complemented the S. cerevisiae erg19 temperature-sensitive mutant, demonstrating conserved catalytic function in the mevalonate pathway across species.

   Evidence Functional complementation of yeast erg19 mutant by C. albicans MVD cDNA

   PMID:12073030

   Open questions at the time

   • No direct biochemical kinetics or substrate specificity determined for the human enzyme
   • No crystal structure of the human MVD at this point
2. 2003 Medium

   Connecting MVD to a non-canonical signaling role: identification of mortalin as a physical interactor revealed that MVD can modulate Ras/ERK signaling beyond its metabolic enzyme function, as co-expression of MVD rescued mortalin-mediated suppression of Ras and phospho-ERK2.

   Evidence Yeast two-hybrid screen, mammalian co-immunoprecipitation, overexpression rescue of Ras/ERK levels

   PMID:12646231

   Open questions at the time

   • Reciprocal endogenous Co-IP not shown; interaction awaits confirmation at endogenous levels
   • Whether the MVD–mortalin interaction requires enzymatic activity or is a scaffolding function is unknown
   • No in vivo validation of the Ras/ERK modulation
3. 2009 Low

   Computational modeling of the yeast MVD active site proposed a water-mediated deprotonation mechanism for decarboxylation and identified candidate substrate-binding and ATP-binding residues, providing a structural framework for future mutagenesis.

   Evidence Molecular docking and MD simulation of S. cerevisiae MVD crystal structure

   PMID:19653015

   Open questions at the time

   • Purely computational; no experimental mutagenesis validation of predicted residues
   • Simulations used yeast enzyme; relevance to human MVD active-site geometry unconfirmed
   • No inhibitor potency data generated
4. 2019 High

   Demonstrating that biallelic MVD loss causes porokeratosis: paired exome sequencing of lesional versus non-lesional tissue revealed germline heterozygous MVD mutations combined with somatic second-hit events in each lesion, establishing a two-hit tumor-suppressor-like mechanism for clonal keratinocyte expansion.

   Evidence Whole-exome sequencing of paired lesional skin and blood/saliva in multiple porokeratosis patients, independently confirmed by targeted sequencing of individual DSAP lesions

   PMID:30942823 PMID:31207227

   Open questions at the time

   • The specific downstream metabolite or signaling deficiency (isoprenoid depletion vs. mevalonate accumulation) driving lesion formation is not resolved
   • Whether restoring MVD activity can reverse established lesions is untested
5. 2021 Low

   Extending MVD deficiency phenotypes: a homozygous missense MVD variant segregated with profound prelingual sensorineural hearing loss in a consanguineous family, and MVD protein was localized to spiral ganglion cells in the mouse cochlea, suggesting a role in auditory neuron function.

   Evidence Exome sequencing with linkage analysis in a Pakistani family; immunohistochemistry in mouse cochlea

   PMID:34135477

   Open questions at the time

   • No functional rescue or enzymatic assay performed for the candidate variant; remains a candidate gene association
   • Whether hearing loss reflects isoprenoid pathway disruption in spiral ganglion neurons is unknown
   • No replication cohort
6. 2023 Medium

   A genetically defined knock-in mouse (MvdF250S/+) revealed that MVD haploinsufficiency attenuates imiquimod-induced skin inflammation—reducing IL-17a, IL-1β, and proliferation while activating autophagy—providing in vivo mechanistic evidence that partial MVD loss alters inflammatory and autophagic responses in skin.

   Evidence CRISPR/Cas9 knock-in heterozygous mouse model with imiquimod challenge, Western blot and cytokine profiling

   PMID:37227548

   Open questions at the time

   • Autophagy activation mechanism (mTOR inhibition vs. isoprenoid depletion) not delineated
   • Homozygous knock-in or conditional keratinocyte knockout not reported
   • Whether Fabp3 upregulation is a direct metabolic compensation remains uncharacterized

• The precise downstream metabolic deficiency (isopentenyl diphosphate depletion, toxic mevalonate accumulation, or specific isoprenoid shortage) that triggers keratinocyte clonal expansion in porokeratosis and the structural basis of human MVD catalysis remain unresolved.
• No crystal structure of human MVD
• No metabolomic profiling of MVD-deficient keratinocytes
• Whether the MVD–mortalin interaction is physiologically relevant in skin or immune cells is untested