Recombinant Gorilla gorilla gorilla Taste receptor type 2 member 46 (TAS2R46)

How is recombinant Gorilla gorilla gorilla TAS2R46 typically produced for research?

Recombinant Gorilla gorilla gorilla TAS2R46 is typically produced using E. coli expression systems . The protein is generally supplied in liquid form containing glycerol to maintain stability during storage and handling . For optimal use in research applications, the recombinant protein should be stored at -20°C, with extended storage recommended at -20°C or -80°C . Working aliquots can be maintained at 4°C for up to one week, though repeated freezing and thawing should be avoided to maintain protein integrity and functionality .

How has TAS2R46 evolved compared to other bitter taste receptors?

Phylogenetic analysis indicates that the TAS2R43-47 group, which includes TAS2R46, evolved more recently compared to other bitter taste receptors like TAS2R10 . This group underwent a series of diversification events from their common ancestor, with an acceleration of gene duplication accompanied by increased functional divergence . According to the estimated relative times of divergence, among the five human TAS2R receptors in this clade, hTAS2R46 diverged first, followed by hTAS2R47, hTAS2R45, hTAS2R43, and lastly hTAS2R44 . In contrast, hTAS2R10 is inferred to have evolved much earlier with a lower relative divergence rate of 1.52 (compared to 1.98 for hTAS2R46) .

What are the key evolutionary differences between TAS2R46 and TAS2R10 in primates?

The evolutionary trajectories of TAS2R46 and TAS2R10 differ significantly in primates. Human TAS2R10 appears to have diverged last among all the sampled TAS2R10s in primates, canids, felidae, and panda, showing high conservation across these species . In contrast, human TAS2R46 diverged later in evolutionary history but prior to TAS2R46s in other primates such as gorilla, chimpanzee, and bonobo . This suggests different selective pressures on these two receptor types throughout primate evolution. Additionally, TAS2R10 shows greater conservation of key functional residues across species compared to TAS2R46, which displays higher variability in these residues .

What evolutionary adaptations enable TAS2R46 to recognize specific ligands like strychnine?

The ability of TAS2R46 to recognize specific ligands like strychnine is determined by key amino acid residues that facilitate binding and receptor activation. Research identifies 11 key residues in human TAS2R46 that are important for strychnine recognition . These include Y241 at position 6.51, which forms hydrogen bonds with strychnine, and variations in this position can significantly affect activation levels . Other key residues include N92 at position 3.36, and variations such as E253K (as seen in gorilla and bonobo TAS2R46) could potentially reduce strychnine responsiveness . The 100% conservation of key functional residues between Neanderthal and human TAS2R46 indicates that the ability to recognize strychnine was acquired before their divergence over 400,000 years ago .

How does TAS2R46 activation affect oxidative stress in immune cells?

TAS2R46 activation by specific agonists like absinthin has been shown to protect monocytes and macrophages from oxidative stress damage . Studies demonstrate that absinthin counteracts the release of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in these cells . In monocytes and both M1 and M2 macrophages, absinthin significantly reduced PMA-induced oxidative burst in a dose-dependent manner . This effect was reversed by the bitter antagonist 3HP, confirming the role of TAS2R46 in this protective mechanism . Additionally, absinthin prevented PMA-induced changes in SOD1 and GPX1 expression, restoring it to baseline levels . This suggests that TAS2R46 may play a critical role in maintaining redox balance in immune cells.

What signaling pathways are activated by TAS2R46 in different cell types?

While the search results don't provide comprehensive details on all signaling pathways activated by TAS2R46 across different cell types, they indicate that TAS2R46 activation in monocytes and macrophages modulates oxidative pathways . In these cells, TAS2R46 activation appears to influence the production of ROS and RNS, suggesting interaction with cellular redox mechanisms . In other cell types, such as bronchial epithelial cells, TAS2R46 activation by absinthin has been shown to inhibit PMA-induced production of superoxide anion, indicating anti-inflammatory and antioxidant activity . The specific downstream signaling cascades may vary by cell type, but the protective effects against oxidative stress appear to be a consistent feature of TAS2R46 activation.

What are the best experimental approaches to study TAS2R46 activation in immune cells?

Based on the research methodologies described in the search results, several experimental approaches are effective for studying TAS2R46 activation in immune cells:

• Quantitative PCR and TaqMan assays: For measuring TAS2R46 expression levels in different cell types and comparing expression with other TAS2R subtypes .

• Immunofluorescence: For visualizing and confirming protein expression of TAS2R46 in different cell populations .

• Oxidative burst assays: Using compounds like PMA to induce oxidative stress, followed by measurement of superoxide anion production to assess TAS2R46-mediated protection .

• Agonist and antagonist treatments: Using specific TAS2R46 agonists (like absinthin) and antagonists (like 3HP) to confirm receptor-specific effects .

• Single-cell gel electrophoresis assays: For evaluating DNA damage protection provided by TAS2R46 activation .

• Analysis of antioxidant enzyme expression: Measuring changes in SOD1 and GPX1 expression to understand how TAS2R46 modulates cellular redox mechanisms .

What are the challenges in working with recombinant Gorilla gorilla gorilla TAS2R46?

While the search results don't explicitly detail challenges specific to recombinant Gorilla gorilla gorilla TAS2R46, several general considerations can be inferred:

• Protein stability: Recombinant TAS2R46 requires specific storage conditions (-20°C or -80°C for extended storage) and should not undergo repeated freeze-thaw cycles .

• Functional assays: As a G protein-coupled receptor, TAS2R46 functional studies likely require appropriate cellular contexts to assess signaling capabilities.

• Species-specific variations: Key amino acid differences between gorilla and human TAS2R46 may affect ligand recognition and signaling properties, necessitating species-specific validation of experimental results .

• Expression systems: While E. coli is used for production , membrane protein expression in bacterial systems can present folding and functionality challenges that may require optimization.

• Standardization: The lack of standardized assays specifically for gorilla TAS2R46 may necessitate adaptation of protocols developed for human or other primate receptors.

What therapeutic potential does TAS2R46 hold for inflammatory and oxidative stress-related conditions?

TAS2R46 shows significant therapeutic potential for inflammatory and oxidative stress-related conditions based on its demonstrated protective effects. Research has shown that TAS2R46 activation by absinthin counteracts the release of reactive oxygen species and reactive nitrogen species in monocytes and macrophages, reducing DNA damage in these cell types . This protective effect against oxidative stress could be particularly valuable in conditions characterized by excessive inflammatory responses and oxidative damage.

The ability of TAS2R46 to modulate immune cell function without impairing antimicrobial activity suggests potential applications in infectious and inflammatory diseases . While the release of ROS from monocytes/macrophages is fundamental for fighting pathogens, supraphysiological ROS production can impair cell function and lead to cell death . TAS2R46 activation appears to help maintain this balance, supporting the cells' protective functions while preventing self-damage.

Research has also identified TAS2R46 as playing protective roles in other tissues, including bronchial epithelial cells, suggesting broad therapeutic applications across multiple organ systems .

How can comparative studies between gorilla and human TAS2R46 inform our understanding of bitter taste receptor evolution?

Comparative studies between gorilla and human TAS2R46 can provide valuable insights into bitter taste receptor evolution and adaptation. The evolutionary analysis indicates that human TAS2R46 diverged after gorilla TAS2R46, suggesting potential functional adaptations specific to the human lineage . By examining the key amino acid differences between gorilla and human TAS2R46, researchers can identify specific residues that might have been under selective pressure during primate evolution.

Studies have shown that variations in key residues can significantly affect receptor function and ligand binding. For instance, differences in positions like N92 and E253 in gorilla TAS2R46 compared to the human receptor may influence their response to compounds like strychnine . Comparative functional studies could reveal how these differences translate to varied sensitivities to bitter compounds between species.

Such research can help elucidate how dietary adaptations, environmental pressures, and other evolutionary factors shaped bitter taste receptor diversity across primates, potentially revealing how these receptors were co-opted for additional functions beyond taste perception.

What are the most promising TAS2R46 agonists for research applications, and how do they compare in efficacy?

Based on the search results, absinthin appears to be a particularly promising and well-studied TAS2R46 agonist for research applications. Absinthin is a specific agonist of TAS2R46 that belongs to the sesquiterpene lactone family . Its efficacy has been demonstrated in several experimental models:

• In monocytes and macrophages: Absinthin significantly reduced PMA-induced oxidative burst in a dose-dependent manner . This effect was specific to TAS2R46, as it was reversed by the bitter antagonist 3HP .

• In bronchial epithelial cells: Absinthin has shown anti-inflammatory and antioxidant activity by inhibiting PMA-induced production of superoxide anion .

• In murine models: Both in vivo and ex vivo studies have demonstrated absinthin's antioxidant and anti-inflammatory properties .

The search results don't provide direct comparisons with other TAS2R46 agonists, though they do mention that absinthin differs from other bitter agonists like strychnine and denatonium by its characteristic chemical structure . Strychnine is discussed as another ligand for TAS2R46, with specific amino acid residues involved in its recognition identified , but comparative efficacy data is not provided.