<p>As we developed a brand-new way to alleviate IBD utilizing muscone molecular switch to induce lactic acid secretion, our contribution for future iGEM teams can be discussed in 2 sections: Parts and Treatment for IBD.</p>
<p>During the preparation for our iGEM competition, we not only continuously improved and enhanced our project by designing an engineered bacteria project for the auxiliary treatment of IBD but also hoped to provide some assistance to future iGEM teams and participants through our efforts. This section introduces the contributions we have made for future teams and members, which involve the design of new synthetic biology composite part, new physiological models, training in experimental skills, and inclusivity.</p>
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<h3>Muscone molecular switch in Saccharomyces cerevisiae: Great treatment experience without pain or regular medication</h3>
<p>We selected the muscone gas molecule as the upstream control signal for the therapeutic system. We utilized the muscone receptor MOR215-1 from mouse olfactory epithelial cells and introduced it into a plasmid system expressed in Saccharomyces cerevisiae. Subsequently, we chose the mating pathway in Saccharomyces cerevisiae as the signal transduction pathway for the muscone signal within the yeast. Based on the corresponding literature, we optimized and replaced five amino acids at the C-terminus of the Gα protein in the original mating pathway, enabling the muscone receptor to be integrated into the mating pathway of Saccharomyces cerevisiae. Ultimately, this allows for the expression of downstream genes through the pFUS1 promoter. This composite part can be utilized in future iGEM design for brand-new smell-induced treatment.</p>
<h2id="Parts">
<h2>New synthetic biology composite part</h2>
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<h3>Muscone-gated molecular switch in Saccharomyces cerevisiae</h3>
<pstyle="text-align: center; font-size: 0.9em; margin-top: 10px;">fig 1 The design of Muscone-gated molecular switch in Saccharomyces cerevisiae</p>
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<p>One of our standout contributions to synthetic biology tools is the construction of a Muscone-gated molecular switch in Saccharomyces cerevisiae BBa_K5187006. The muscone receptor is a type of GPCR derived from mice. We designed the corresponding Gα protein by modifying the amino acid sequence so that it can trigger the mating pathway in Saccharomyces cerevisiae, thereby further inducing the expression of downstream genes.</p>
<p>It is worth noting that this molecular switch in Saccharomyces cerevisiae is an original contribution from our team. Although in our experiment it was applied to secrete lactic acid for the treatment of IBD, this downstream element can be replaced with any other gene to achieve different biological functions. We believe that this minute, efficient, and cost-effective molecular switch will have broad application scenarios in related industries.</p>
<p>Simultaneously, we have conducted molecular dynamics simulations to predict the binding of muscone molecules to their receptors, providing a more detailed and quantitative explanation of the biological process of the muscone-gated molecular switch. This aims to assist future research teams in obtaining more molecular dynamics information about this molecular switch and developing more functions of the switch. For more information, please refer to <ahref="https://2024.igem.wiki/Tsinghua/model#topic2"style="color: #FF5151">Model: Binding</a>.</p>
<p>For more information about the Muscone-gated molecular switch in Saccharomyces cerevisiae, please refer to <ahref="https://2024.igem.wiki/Tsinghua/parts"style="color: #FF5151">Parts</a>.</p>
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<h3>Tetrathionate Sensing Colonization System: High efficiency in treatment</h3>
<p>We selected the signaling pathway of the sensor, designed by a previous team, that can detect tetrathionate (a marker of IBD) and we connected the ALS3 adhesion protein downstream. When the system detects the marker of IBD, Saccharomyces cerevisiae can adhere to the intestinal tract by expressing the ALS3 protein, achieving the colonization of the engineered strain. Future iGEM may refer our design when considering colonization in guts for other diseases.</p>
<p>Out of consideration for biosafety, our project did not conduct any animal experiments. To verify the effectiveness of the project, we designed a full-process human physiological model from inhalation of gases to therapeutic secretion, providing a detailed explanation of our project's treatment process through modeling.</p>
<p>Considering the current scarcity of gas-based treatment methods, there is very little research on models of gas flow and changes within the human body. Our project offers a model of the flow and changes of muscone gas molecules within the human body for studying the effectiveness of our project. This model can provide a reference for future iGEM teams and members who wish to study gas flow and changes within the human body, especially for those targeting engineered bacteria colonization in the intestinal segment.</p>
<p>We have established models for the entire process from the entry of signaling molecules into the human body to the activation of engineered bacteria for drug secretion. This not only perfects the detailed description of our project's treatment process but also provides design ideas and a framework for future iGEM teams and members interested in researching engineered bacteria colonization projects in the intestine.</p>
<p>For more information about our physiological model, please refer to <ahref="https://2024.igem.wiki/Tsinghua/model"style="color: #FF5151">Model</a>.</p>
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<h2id="Treatment for IBD">
<h2>Treatment for IBD</h2>
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<p>As we mentioned in Parts section, we utilize innovative pathways in Yeast, in order to secrete lactic acid in focuses of IBD. We are confident this treatment can not only contribute to future iGEM teams or iGEM community but also IBD patient community.</p>
<p>Current IBD treatments typically involve surgery or drug therapy. However, surgery does not address the root cause of the disease and may lead to numerous complications. Existing drug therapies, primarily anti-inflammatory drugs and immune system suppressors, can help alleviate IBD but carry risks, including an increased likelihood of cancer or immune system disorders within the intestinal tract.</p>
<p>Due to these concerns, Tsinghua iGEM 2024 introduces lactic acid into IBD treatment. Lactic acid secreted by lactic acid bacterial has been shown to limit autoimmunity and alleviate inflammatory conditions in the gut. As lactic acid is naturally present in the human gut and secreted by probiotics, using it as a treatment offers minimal side effects while providing significant relief for IBD symptoms.</p>
<p>In our project we combined the innovative Muscone molecular switch with lactic acid secretion pathway in yeast, with the combination, patients will no longer to take regular medication. All they need to do is turn on the Muscone Generator after having taken the Genetically modified yeast. And with our colonization system, the treatment will be high efficient and also have minimal influence on other healthy parts in gut</p>
<p>We hope this method can make a real contribution to the IBD patient community in the future, as we know they are currently burdened by painful treatments. For future iGEM teams focusing on IBD, we also hope our approach provides valuable insight and inspires the development of even better treatments.</p>
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<h2id="Experimental skill">
<h2>About experimental teaching video</h2>
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<p>In order to popularize knowledge about molecular biology experiments used in synthetic biology, we have registered accounts on various video media platforms such as Tiktok, Bilibili, and YouTube. Based on the experimental content of our project, we have produced and released a series of instructional videos on molecular biology experimental skills in both Chinese and English versions, helping more people learn related experimental techniques.</p>
<p>For more information about the instructional videos, please refer to <ahref="https://2024.igem.wiki/Tsinghua/education#Public"style="color: #FF5151">Education: Public</a>.</p>
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<h2>References</h2>
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<p>[1] Chen, Y., Gao, H., Zhao, J., Ross, R.P., Stanton, C., Zhang, H., Chen, W., & Yang, B. (2023). Exploiting lactic acid bacteria for inflammatory bowel disease: A recent update. Trends in Food Science & Technology.</p>
<p>[2] Wu, Xin et al. (2024). AAV-delivered muscone-induced transgene system for treating chronic diseases in mice via inhalation. Nature communications.</p>
