ARBA00089174 adaptive thermogenesis (GO:1990845)

id: ARBA00089174
description: 'Rule predicting adaptive thermogenesis (GO:1990845) based on two alternative
  condition sets: PM20D1 FunFams in Eukaryota, and TRPV1 FunFams in Mus. The rule
  captures two mechanistically distinct pathways to thermogenic regulation.'
status: COMPLETE
rule_type: ARBA
rule:
  rule_id: ARBA00089174
  condition_sets:
  - number: 1
    conditions:
    - condition_type: FUNFAM
      value: 1.10.150.900:FF:000003
      curie: CATH.FunFam:1.10.150.900:FF:000003
      label: N-fatty-acyl-amino acid synthase/hydrolase PM20D1
      negated: false
    - condition_type: FUNFAM
      value: 3.40.630.10:FF:000027
      curie: CATH.FunFam:3.40.630.10:FF:000027
      label: N-fatty-acyl-amino acid synthase/hydrolase PM20D1
      negated: false
    - condition_type: TAXON
      value: '2759'
      curie: NCBITaxon:2759
      label: Eukaryota
      negated: false
    notes: PM20D1 is a secreted enzyme that synthesizes and hydrolyzes N-fatty-acyl
      amino acids (NAAs). NAAs can act as mitochondrial uncouplers, promoting UCP1-independent
      thermogenesis. The Eukaryota scope is overly broad since adaptive thermogenesis
      is primarily a mammalian physiological trait.
    pairwise_overlap:
    - condition_a: 1.10.150.900:FF:000003
      condition_b: 3.40.630.10:FF:000027
      protein_database: SWISSPROT
      count_a: 10
      count_b: 10
      intersection_count: 10
      a_minus_b_count: 0
      b_minus_a_count: 0
      jaccard_similarity: 1.0
      containment_a_in_b: 1.0
      containment_b_in_a: 1.0
      interpretation: REDUNDANT
  - number: 2
    conditions:
    - condition_type: FUNFAM
      value: 1.10.287.70:FF:000074
      curie: CATH.FunFam:1.10.287.70:FF:000074
      label: Transient receptor potential cation channel subfamily V member 1
      negated: false
    - condition_type: FUNFAM
      value: 1.25.40.20:FF:000018
      curie: CATH.FunFam:1.25.40.20:FF:000018
      label: Transient receptor potential cation channel subfamily V member 1
      negated: false
    - condition_type: TAXON
      value: '862507'
      curie: NCBITaxon:862507
      label: Mus
      negated: false
    notes: TRPV1 is a heat/capsaicin-gated cation channel. In mice, TRPV1 activation
      triggers the SIRT1→PRDM16→UCP1 pathway in adipose tissue, enhancing thermogenic
      programming. The Mus restriction is appropriate given that evidence is primarily
      from murine models.
    pairwise_overlap:
    - condition_a: 1.10.287.70:FF:000074
      condition_b: 1.25.40.20:FF:000018
      protein_database: SWISSPROT
      count_a: 10
      count_b: 13
      intersection_count: 10
      a_minus_b_count: 0
      b_minus_a_count: 3
      jaccard_similarity: 0.7692307692307693
      containment_a_in_b: 1.0
      containment_b_in_a: 0.7692307692307693
      interpretation: SUBSET
  go_annotations:
  - go_id: GO:1990845
    go_label: adaptive thermogenesis
    aspect: BP
  reviewed_protein_count: 0
  unreviewed_protein_count: 0
  created_date: '2025-03-21'
  modified_date: '2025-03-21'
  entries:
  - id: 1.10.150.900:FF:000003
    type: FUNFAM
    label: N-fatty-acyl-amino acid synthase/hydrolase PM20D1
    appears_in_condition_sets:
    - 1
    protein_count: 10
    related_entries:
    - relationship: EQUIV
      target_id: 3.40.630.10:FF:000027
      containment: 1.0
      jaccard_similarity: 1.0
      intersection_count: 10
      exclusive_count: 0
    - relationship: EQUIV
      target_id: 1.10.287.70:FF:000074
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 10
    - relationship: EQUIV
      target_id: 1.25.40.20:FF:000018
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 10
    - relationship: PREDICTS
      target_id: GO:1990845
      containment: 0.7
      jaccard_similarity: 0.051
      intersection_count: 7
      exclusive_count: 3
  - id: 1.10.287.70:FF:000074
    type: FUNFAM
    label: Transient receptor potential cation channel subfamily V member 1
    appears_in_condition_sets:
    - 2
    protein_count: 10
    related_entries:
    - relationship: EQUIV
      target_id: 1.10.150.900:FF:000003
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 10
    - relationship: EQUIV
      target_id: 3.40.630.10:FF:000027
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 10
    - relationship: PREDICTS
      target_id: 1.25.40.20:FF:000018
      containment: 1.0
      jaccard_similarity: 0.769
      intersection_count: 10
      exclusive_count: 0
    - relationship: PREDICTS
      target_id: GO:1990845
      containment: 0.7
      jaccard_similarity: 0.051
      intersection_count: 7
      exclusive_count: 3
  - id: 1.25.40.20:FF:000018
    type: FUNFAM
    label: Transient receptor potential cation channel subfamily V member 1
    appears_in_condition_sets:
    - 2
    protein_count: 13
    related_entries:
    - relationship: EQUIV
      target_id: 1.10.150.900:FF:000003
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 13
    - relationship: EQUIV
      target_id: 3.40.630.10:FF:000027
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 13
    - relationship: PREDICTED_BY
      target_id: 1.10.287.70:FF:000074
      containment: 0.769
      jaccard_similarity: 0.769
      intersection_count: 10
      exclusive_count: 3
    - relationship: PREDICTS
      target_id: GO:1990845
      containment: 0.538
      jaccard_similarity: 0.05
      intersection_count: 7
      exclusive_count: 6
  - id: 3.40.630.10:FF:000027
    type: FUNFAM
    label: N-fatty-acyl-amino acid synthase/hydrolase PM20D1
    appears_in_condition_sets:
    - 1
    protein_count: 10
    related_entries:
    - relationship: EQUIV
      target_id: 1.10.150.900:FF:000003
      containment: 1.0
      jaccard_similarity: 1.0
      intersection_count: 10
      exclusive_count: 0
    - relationship: EQUIV
      target_id: 1.10.287.70:FF:000074
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 10
    - relationship: EQUIV
      target_id: 1.25.40.20:FF:000018
      containment: 0.0
      jaccard_similarity: 0.0
      intersection_count: 0
      exclusive_count: 10
    - relationship: PREDICTS
      target_id: GO:1990845
      containment: 0.7
      jaccard_similarity: 0.051
      intersection_count: 7
      exclusive_count: 3
review_summary: 'This rule captures two mechanistically distinct pathways to adaptive
  thermogenesis: (1) PM20D1 functions as a bidirectional synthase/hydrolase regulating
  N-acyl amino acids (NAAs) that act as mitochondrial uncouplers for UCP1-independent
  thermogenesis, and (2) TRPV1 acts as a thermosensory and metabolic signaling node
  that activates thermogenic gene programs via Ca2+→CaMKII/AMPK→SIRT1→PRDM16→UCP1
  pathway. Critically, PM20D1 is a direct thermogenic executor while TRPV1 is a thermogenic
  regulator— TRPV1''s primary functions are nociception and temperature sensation,
  with thermogenesis being a secondary role. PM20D1 operates cooperatively with FAAH
  in NAA homeostasis. Both mechanisms are supported by murine studies, with PM20D1
  human genetic associations. Two modifications recommended: (a) restrict PM20D1''s
  Eukaryota scope to Mammalia, (b) consider GO:1990847 (positive regulation of adaptive
  thermogenesis) for precision. The TRPV1 Mus restriction may be overly conservative—evidence
  exists in rats and other mammals.'
action: MODIFY
action_rationale: The rule is biologically plausible but requires two modifications.
  First, the PM20D1 condition set's Eukaryota scope should be restricted to Mammalia
  (or at most Vertebrata) since adaptive thermogenesis is a mammalian physiological
  program. Propagating this annotation to plants, fungi, or invertebrates would create
  false positives. Second, the GO term GO:1990845 (adaptive thermogenesis) describes
  an organism-level process; both PM20D1 and TRPV1 are regulatory proteins that modulate
  thermogenesis rather than directly executing it. A more precise annotation would
  be "positive regulation of adaptive thermogenesis" (GO:1990847) for both proteins.
suggested_modifications:
- Restrict PM20D1 condition set from Eukaryota to Mammalia
- Consider changing GO term from GO:1990845 to GO:1990847 (positive regulation of
  adaptive thermogenesis)
- For TRPV1, consider extending Mus restriction to Mammalia if corroborating mammalian
  evidence is curated
- Add evidence qualifiers noting UCP1-independent mechanism for PM20D1 and PRDM16/UCP1-dependent
  mechanism for TRPV1
parsimony:
  assessment: REDUNDANT
  notes: Rule contains perfect redundancy between two PM20D1 FunFams with identical
    10-protein sets. In CS1, 1.10.150.900:FF:000003 ≡ 3.40.630.10:FF:000027 (containment=1.0,
    jaccard=1.0, intersection=10/10 proteins). One FunFam should be removed to eliminate
    redundancy. The two condition sets capture mechanistically distinct pathways to
    thermogenesis - PM20D1 operates via NAA-mediated mitochondrial uncoupling (UCP1-independent),
    while TRPV1 operates via the SIRT1→PRDM16→UCP1 axis (UCP1-dependent).
literature_support:
  assessment: STRONG
  notes: 'Both pathways have strong experimental support from multiple complementary
    approaches. PM20D1: AAV-mediated overexpression increases circulating NAAs and
    energy expenditure; genetic knockout causes dysregulated glucose homeostasis;
    bidirectional manipulation proves causal role. PM20D1 expression is cold-inducible
    and UCP1-knockout mice retain PM20D1-dependent thermogenesis, demonstrating independence.
    Natural promoter variants in BALB/c vs C57BL/6 mice explain strain-specific cold
    tolerance differences. Human PM20D1 variants associate with BMI and metabolic
    syndrome. PM20D1 operates cooperatively with FAAH in a two-enzyme NAA regulatory
    system. TRPV1: activation induces UCP1/PGC1α expression in adipocytes; fish oil
    activates adipocyte TRPV1 inducing thermogenic genes; TRPV1 knockout mice show
    hyperthermia and impaired thermoregulation; hypothalamic TRPV1 coordinates behavioral
    thermoregulation. Clinical trials show TRPV1 antagonists cause hyperthermia, providing
    human evidence. However, most TRPV1 literature focuses on nociception—thermogenesis
    is a secondary but genuine functional role.'
  supported_by:
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity.md
    supporting_text: PM20D1 does not operate in isolation but rather functions as
      part of a cooperative enzymatic system controlling N-acyl amino acid homeostasis
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity.md
    supporting_text: TRPV1 activation in adipocytes through both pharmacological means
      and physiological triggers robustly induces UCP1 expression and thermogenic
      gene programs
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-falcon.md
    supporting_text: Capsaicin-induced TRPV1 activation increases BAT thermogenic
      program and opposes diet-induced obesity in WT but not TRPV1-/- mice
condition_overlap:
  assessment: NONE
  notes: The two condition sets capture entirely different protein families with distinct
    mechanisms and functional roles. PM20D1 is a secreted M20 peptidase family enzyme
    that functions as a direct thermogenic executor—it synthesizes NAAs that directly
    cause mitochondrial uncoupling and heat production. TRPV1 is a TRP family ion
    channel that functions as a thermogenic regulator/signaling node—it detects thermal
    and metabolic stimuli and activates downstream thermogenic effectors including
    UCP1. This executor vs regulator distinction has implications for annotation granularity.
    No biological or sequence overlap exists between these condition sets, though
    emerging evidence suggests PM20D1-synthesized NAAs may function as endogenous
    TRPV1 ligands, establishing a functional connection between the two pathways.
  supported_by:
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity.md
    supporting_text: PM20D1 functions as a direct thermogenic executor—the enzyme
      synthesizes and regulates metabolites that directly increase heat production
      through mitochondrial uncoupling
go_specificity:
  assessment: TOO_BROAD
  notes: GO:1990845 (adaptive thermogenesis) describes the organism-level physiological
    process. The term is appropriate for PM20D1 which directly executes thermogenesis
    via NAA-mediated mitochondrial uncoupling—however GO:1990847 (positive regulation
    of adaptive thermogenesis) might still be preferred for precision. For TRPV1,
    the term is somewhat broad because TRPV1 functions primarily as a thermosensory
    and signaling node rather than a direct thermogenic executor. TRPV1's primary
    annotated functions emphasize nociception and temperature sensation, with metabolic
    effects as secondary consequences. More specific alternatives for TRPV1 include
    GO:0009409 (response to cold), GO:0019233 (sensory perception of temperature),
    or GO:0055080 (cellular response to heat). Additionally, PM20D1 could receive
    GO:0008610 (lipid biosynthetic process) for NAA synthesis, and TRPV1 could receive
    cation channel activity annotations. The distinction between detecting/signaling
    about thermogenic need (TRPV1) versus directly executing thermogenesis (PM20D1)
    would be better captured through appropriately specific GO terms.
  supported_by:
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity.md
    supporting_text: TRPV1 acts as a thermosensory node rather than as a direct thermogenic
      effector in many contexts
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-falcon.md
    supporting_text: GO:1990845 is an organism-level physiological process; for protein-centric
      annotation, regulation terms are often more precise
taxonomic_scope:
  assessment: TOO_BROAD
  notes: The PM20D1 condition set's Eukaryota (NCBITaxon:2759) scope is clearly too
    broad. Adaptive thermogenesis is a mammalian physiological trait requiring brown/beige
    adipose tissue and sympathetic nervous system coordination—structures absent in
    plants, fungi, and invertebrates. PM20D1 orthologs in non-mammalian eukaryotes
    may serve alternative metabolic functions unrelated to thermogenesis. The scope
    should be restricted to Mammalia, or conservatively to placental mammals (Eutheria).
    For TRPV1, the Mus restriction may be overly conservative. Experimental evidence
    for TRPV1-thermogenesis connections exists in rats and other rodent species, and
    human clinical trials with TRPV1 antagonists show hyperthermia (though this reflects
    impaired heat loss rather than defective heat production). Consider expanding
    to Rodentia or Mammalia with evidence review. TRPV1 orthologs exist in birds and
    reptiles but physiological context differs substantially and dedicated thermogenesis
    evidence is lacking, so expansion beyond mammals should be cautious.
  supported_by:
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity.md
    supporting_text: The restriction of TRPV1 annotation to Mus may be overly conservative
      and should be evaluated for potential expansion to include other mammalian species
  - reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-falcon.md
    supporting_text: Adaptive thermogenesis is a mammalian trait. Expanding annotation
      to Eukaryota invites false positives (e.g., plants, fungi, invertebrates)
confidence: 0.85
references:
- id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity.md
  title: Deep research analysis via Perplexity (47 citations, comprehensive)
  findings:
  - statement: PM20D1 is a bidirectional synthase/hydrolase that operates cooperatively
      with FAAH as part of a two-enzyme NAA regulatory system. PM20D1 regulates extracellular
      pools while FAAH regulates intracellular pools.
  - statement: PM20D1 functions as a direct thermogenic executor—it synthesizes NAAs
      that directly cause mitochondrial uncoupling and heat production. This represents
      UCP1-independent thermogenesis.
  - statement: TRPV1 functions as a thermogenic regulator/signaling node that couples
      environmental and metabolic stimuli to downstream effectors including UCP1.
      Its primary functions are nociception and temperature sensation—thermogenesis
      is secondary.
  - statement: Natural promoter variants in BALB/c vs C57BL/6 mice cause PM20D1 expression
      differences explaining strain-specific cold tolerance. Human PM20D1 variants
      associate with BMI and metabolic syndrome.
  - statement: Central hypothalamic TRPV1 coordinates behavioral thermoregulation;
      TRPV1 knockout mice show hyperthermia on warm exposure. Clinical trials with
      TRPV1 antagonists cause hyperthermia, providing human relevance.
  - statement: PM20D1 Eukaryota scope should be restricted to Mammalia. TRPV1 Mus
      restriction may be overly conservative—consider expanding to Rodentia or Mammalia.
- id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-falcon.md
  title: Deep research analysis via Falcon (10 citations)
  findings:
  - statement: PM20D1 regulates N-acyl amino acids (NAAs) that bind mitochondria and
      act as UCP1-independent uncouplers. Mouse genetics show PM20D1 expression bidirectionally
      impacts cold tolerance and BAT respiration.
  - statement: TRPV1 activation via capsaicin triggers Ca2+→CaMKII/AMPK→SIRT1→PRDM16
      deacetylation→PPARγ/PGC-1α→UCP1 pathway in brown adipose tissue.
  - statement: At thermoneutrality, capsaicin's anti-obesity effects require both
      PRDM16 and UCP1, demonstrating genetic dependency on the thermogenic program.
- id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity-lite.md
  title: Deep research analysis via Perplexity-lite (10 citations)
  findings:
  - statement: PM20D1 knockout mice show reduced energy expenditure and impaired thermogenic
      response to cold.
  - statement: TRPV1 activation increases BAT activity and energy expenditure by up
      to 10-15% in murine models exposed to capsaicin or cold.
supported_by:
- reference_id: file:rules/arba/ARBA00089174/ARBA00089174-deep-research-perplexity.md
  supporting_text: PM20D1 and TRPV1 do participate in adaptive thermogenesis, and
    their identification through structural domain signatures represents a valid approach
    to functional annotation