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TRPA1 is a polyunsaturated fatty acid sensor in mammals.

ABSTRACT: Fatty acids can act as important signaling molecules regulating diverse physiological processes. Our understanding, however, of fatty acid signaling mechanisms and receptor targets remains incomplete. Here we show that Transient Receptor Potential Ankyrin 1 (TRPA1), a cation channel expressed in sensory neurons and gut tissues, functions as a sensor of polyunsaturated fatty acids (PUFAs) in vitro and in vivo. PUFAs, containing at least 18 carbon atoms and three unsaturated bonds, activate TRPA1 to excite primary sensory neurons and enteroendocrine cells. Moreover, behavioral aversion to PUFAs is absent in TRPA1-null mice. Further, sustained or repeated agonism with PUFAs leads to TRPA1 desensitization. PUFAs activate TRPA1 non-covalently and independently of known ligand binding domains located in the N-terminus and 5(th) transmembrane region. PUFA sensitivity is restricted to mammalian (rodent and human) TRPA1 channels, as the drosophila and zebrafish TRPA1 orthologs do not respond to DHA. We propose that PUFA-sensing by mammalian TRPA1 may regulate pain and gastrointestinal functions.

SUBMITTER: Motter AL

PROVIDER: S-EPMC3378573 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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TRPA1 is a polyunsaturated fatty acid sensor in mammals.

Motter Arianne L AL Ahern Gerard P GP

PloS one 20120619 6

Fatty acids can act as important signaling molecules regulating diverse physiological processes. Our understanding, however, of fatty acid signaling mechanisms and receptor targets remains incomplete. Here we show that Transient Receptor Potential Ankyrin 1 (TRPA1), a cation channel expressed in sensory neurons and gut tissues, functions as a sensor of polyunsaturated fatty acids (PUFAs) in vitro and in vivo. PUFAs, containing at least 18 carbon atoms and three unsaturated bonds, activate TRPA1 ...[more]

PMID: 22723860

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Project description:BackgroundPolyunsaturated fatty acids (PUFAs) are associated with a lower risk of multiple diseases. Fatty acid desaturase 1 gene (FADS1) polymorphisms and dietary PUFA intake are both established determinants of circulating PUFA proportions.ObjectiveWe explored the joint effects of FADS1 polymorphisms and dietary PUFA intake on circulating PUFA proportions.DesignWe studied 2288 participants from a nested case-control study of coronary artery disease among participants who provided blood samples in the Nurses' Health Study and the Health Professionals Follow-Up Study. Dietary PUFA intake was obtained from semiquantitative food-frequency questionnaires. FADS1 rs174546 was genotyped by using the Affymetrix 6.0 platform, and circulating PUFA proportions were measured with gas-liquid chromatography. Linear regression models were used to examine the associations between rs174546 and circulating proportions of each fatty acid. Gene-diet interactions were tested by including a cross-product term of dietary intake of each PUFA by rs174546 genotype in the linear regression models.ResultsAfter adjustment for sex and ancestry, each copy of the C allele of rs174546 was associated with higher circulating proportions of arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) and lower proportions of linoleic acid and α-linolenic acid. The magnitude of positive association between higher consumption of dietary EPA or DHA and circulating proportions of EPA increased with each copy of the rs174546_T allele (P-interaction = 0.01 and 0.007, respectively). Each 1-SD increment in EPA intake was associated with an average 3.7% increase in circulating EPA proportions among participants with the rs174546_CC genotype and an average 7.8% increase among participants with the TT genotype.ConclusionsCarriers of the T allele at FADS1 rs174546 may need higher doses of dietary EPA and DHA to achieve the same circulating proportions of EPA as carriers of the C allele. The implications of these findings on disease risk and dietary guidelines require further study.

Project description:Streptococcus pneumoniae, a major cause of pneumonia, sepsis, and meningitis worldwide, has the nasopharynges of small children as its main ecological niche. Depletion of pneumococci from this niche would reduce the disease burden and could be achieved using small molecules with narrow-spectrum antibacterial activity. We identified the alkylated dicyclohexyl carboxylic acid 2CCA-1 as a potent inducer of autolysin-mediated lysis of S. pneumoniae, while having low activity against Staphylococcus aureus 2CCA-1-resistant strains were found to have inactivating mutations in fakB3, known to be required for uptake of host polyunsaturated fatty acids, as well as through inactivation of the transcriptional regulator gene fabT, vital for endogenous, de novo fatty acid synthesis regulation. Structure activity relationship exploration revealed that, besides the central dicyclohexyl group, the fatty acid-like structural features of 2CCA-1 were essential for its activity. The lysis-inducing activity of 2CCA-1 was considerably more potent than that of free fatty acids and required growing bacteria, suggesting that 2CCA-1 needs to be metabolized to exert its antimicrobial activity. Total lipid analysis of 2CCA-1 treated bacteria identified unique masses that were modeled to 2CCA-1 containing lysophosphatidic and phosphatidic acid in wild-type but not in fakB3 mutant bacteria. This suggests that 2CCA-1 is metabolized as a fatty acid via FakB3 and utilized as a phospholipid building block, leading to accumulation of toxic phospholipid species. Analysis of FabT-mediated fakB3 expression elucidates how the pneumococcus could ensure membrane homeostasis and concurrent economic use of host-derived fatty acids.IMPORTANCE Fatty acid biosynthesis is an attractive antibiotic target, as it affects the supply of membrane phospholipid building blocks. In Streptococcus pneumoniae, it is not sufficient to target only the endogenous fatty acid synthesis machinery, as uptake of host fatty acids may bypass this inhibition. Here, we describe a small-molecule compound, 2CCA-1, with potent bactericidal activity that upon interactions with the fatty acid binding protein FakB3, which is present in a limited number of Gram-positive species, becomes metabolized and incorporated as a toxic phospholipid species. Resistance to 2CCA-1 developed specifically in fakB3 and the regulatory gene fabT These mutants reveal a regulatory connection between the extracellular polyunsaturated fatty acid metabolism and endogenous fatty acid synthesis in S. pneumoniae, which could ensure balance between efficient scavenging of host polyunsaturated fatty acids and membrane homeostasis. The data might be useful in the identification of narrow-spectrum treatment strategies to selectively target members of the Lactobacillales such as S. pneumoniae.

Project description:Docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (ARA, 20:4n-6) are the major long chain polyunsaturated fatty acids (LCPUFA) of the central nervous system. We examined the alterations in transcriptional profiles in neonate baboon cerebral cortex brain tissue using high-density Affymetrix oligonucleotide arrays ("U133 plus 2.0"). Twelve neonates were divided into 3 groups: Control (C, no DHA-ARA); 1× LCPUFA (L, 0.33%DHA-0.67%ARA); 3× LCPUFA (L3, 1.00%DHA-0.67%ARA). Significance analysis (P < 0.05) of a total of >54,000 probe sets (ps) identified changes in expression levels of 1108 ps, representing 2.05% of the total ps on the oligoarray, with most ps showing <2-fold change. Comparing L and C, 534 ps were upregulated with supplementation, and 574 ps were downregulated. For the L3/C comparisons, 666 ps were upregulated and 442 ps were downregulated. Characterization of differentially regulated genes by gene ontology assign them to diverse biological functions, notably lipid metabolism, ion channel and transport, G-protein and signal transduction, development, visual perception, membrane function, apoptosis, cytoskeleton, peptidases, cell cycle, stress response, kinases and phosphatases, transcription regulation, receptors, and ubiquitin, with about 400 transcripts having no defined function. Of differentially expressed genes involved in lipid metabolism, PLA2G6, a phospholipase recently associated with infantile neuroaxonal dystrophy, was downregulated in both LCPUFA groups. ELOVL5, a PUFA elongase, was the only enzyme in the LCPUFA biosynthetic pathway that was differentially expressed. Mitochondrial fatty acid carrier, CPT2, was among several genes associated with mitochondrial fatty acid oxidation to be downregulated, while the mitochondrial proton carrier, UCP2, was upregulated. PUFA-regulated receptor, Retinoic acid receptor alpha (RARA) was repressed in both groups, while HNF4A, a PUFA regulated factor, was downregulated in L3/C. Genes involved in neural development, TIMM8A, NRG1, SEMA3D and NUMB, were upregulated while HES1 and SIM1 showed decreased expression. LUM, EML2, TIMP3 and TTC8 which have roles in visual perception were upregulated and TIA1, a silencer of COX2 gene translation is upregulated in L3/C. Ingenuity network analysis identified a top network associated with nervous system development and function with EGFR as the outstanding interaction partner. In this network EGFR interacts with genes involved in neural or visual perception, TIMP3, NRG1, ADAM17, EDG7 and FGF7. Quantitative real time-PCR analysis on selected genes confirmed the array results. The L and L3 groups have DHA and ARA content within the ranges observed in human and baboon breastmilk, and thus these data indicate that LCPUFA concentrations within the normal range of human breastmilk induce global changes in gene expression across numerous functions including transcripts involved in neural development, visual perception, etc. Keywords: dietary dose response

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TRPA1 is a polyunsaturated fatty acid sensor in mammals.

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TRPA1 is a polyunsaturated fatty acid sensor in mammals.

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