 Yeah, the spinal cord will combine different signals and then transmit to our brain, especially the sensory cortex, you will feel each. Most of the each receptors are GPCR. So we focus on the GPCR, especially the orphan GPCRs expressed in the Dothelroth ganglion neurons. So these orphan GPCRs, maybe the candidates that mediate these each. Our work, you know that in the lab, to demonstrate a principle, we have found the molecular mechanism of cholestatic each, for example. We have this screened antagonist, and we believe that many pharmaceuticals also want to treat this each because it has a big market. So it can also, to this compound, these companies can also target these each receptor to treat this each. I mean, find the antagonist. Also someone's opinion may contradict yours. Where's my friend Allen? It's all about your perspective. Who are we and what is the nature of this reality? Five, four, three, two, one. Ni hao everybody, and Zhongchekuaile, happy mid-autumn festival. We are in the beautiful Beijing, China. Welcome to Simulation. I'm your host Alan Sakyun. We are at the School of Life Sciences here. We are now going to be talking about the sensory GPCR of itch. We have Tianjun Zhao joining us on the show. Hello. Hi, Jun. Hi, Alan. Thank you so much for coming on our show. Yeah. We really appreciate it. Very excited for this conversation. For those who don't know Jun's background, he's a graduate researcher in the Li Lab at Beijing University School of Life Sciences focused on the sensory GPCR of itch. And you can find all of the links in the bio below. Jun, let's start things off by asking you one of our favorite questions. What are your thoughts on the general direction of our world? Oh, it's an interesting question. Yeah, it's general. And you know that there are more and more technologies for our life, especially it's convenient for our life. Take example, you know that the AliPay you have used it, or the WeChat Pay. So I think for the future, these advanced technologies will help us to battery life in this planet. And I think actually I'm afraid maybe the AI will replace me, yeah, for the future. Yeah, it's probably. And but I think the main difference between the human and the AI is the idea. I think the idea is important. And I don't think that the AI will replace the smartest people in the world because, yeah, you know that as I mentioned, it can help us to this repeated works, repetitive tasks. But the creative ones is much harder for it. It also depends on human. And yeah, yeah, it's totally the general direction of now technology augmenting our lives in so many ways, our health, our education, our day to day processes. AI, narrow AI doing repetitive tasks way better than humans is very quickly happening. But AI doing creative tasks is slow slower at happening right now. And building general intelligence is also very difficult. How do you get a computer system to recognize space and time is very hard. But who knows, in terms of replacement of of us as humans are at least augmenting us for sure, replacing us. We've had that conversation many times on our show. It's for sure a fun one. And we'll see exactly what ends up happening with that. June, let's talk about your journey. So where were you born? How did you pick up your interest in science growing up? Oh, it's a good question. Actually, I'm interested in biology. I mean, the natural science where I was a child. Where were born? Yeah. There, yes. OK, I was born in Shandong province, East province of China. And when I was a kid, I'm interested in, for example, why the most critical will cause us each. So you know that it's terrible, especially when we live near the water. It's very terrible. So how to say, I'm interested in this natural science when I was a child. And when I was an undergraduate student in my university, the Northwestern Algorithmic Cultural Forest University in Xi'an province, the west of China. And because in our university, there is no neuroscience lab. So I searched the literature, and I found that the most critical induced each is very complex. And yeah, till now, we have noticed that it may be caused by some compounds released from our such as the immune cells, and then triggered each. And till now, for me, to me, as more and more research is worth down, the deeper you're thinking or the deeper you're understanding, the more I want to know why. So that's why I'm interested in science. Yes, yes. So when you were a little kid, it was as simple as just why is a mosquito bite caused me to itch? And then that got you when you were in biotechnology at the Northwest A&F University. You've kept going into interest in that. Maybe, and then we'll talk about this move to picking university and doing neuroscience here. But I'm so interested in even the most fundamental aspects of what you were talking about with the mosquito and the itch. What do you know about why we itch from the mosquito bite? OK, you mean your question is whether or why we want to know the magnet of itch? Yeah, and why even the mechanism of itch from the mosquito happens? Why do we itch? It's like the immune response. Oh, yeah, OK. I see, I see. Actually, the itch includes acute itch and chronic itch. The mosquito in itch actually is a acute one. And it means that each last shorter for six weeks. Chronic itch is the last over six weeks, especially on some systemic disease. OK, let's back to the acute itch. The acute itch actually is a protective behavior. It will help us to expel stimulus such as the mosquitoes or some plants, toxic plants. OK, so it's protective for our survival. Yeah, and as for the mechanism, I think it's very complex. It includes the immune system, the neuroscience, the behavioral. Yeah, sometimes it seems like when I get a mosquito bite that if I itch, it lasts longer than if I don't itch. What do you think about that? OK, you mean that the scratch, the more scratch, the more itch. Yeah, more itch equals longer mosquito bite. I see, so detailed the mechanism is unknown. And I think it may be caused by a feedback loop. I mean, the more itch, sorry, the more scratch your skin, the more itch is happen. It's also interesting learning from you that even something as simple as what we experience within a mosquito bite has such a complex, both this peripheral skin layer complex here, plus complex with how it triggers our nervous system and our behavior of doing this process of itch or immune system, all this type of stuff is very complex, even something simple like a mosquito bite. Yeah, I see. Actually, as you mentioned, it's a circuit. It's a neural circuit. OK, the stimuli will, yeah, will activate the sensor in our skin. For example, a receptor, the itch, especially the itch receptor and the signal will transmit to the spinal cord. Yeah, the spinal cord will combine different signals and then transmit to our brain, especially the sensory cortex, you will feel itch. And, yeah, the upstream is the receptor. I mean, the sensors that are stimulated or activated by the external stimuli and these receptors mainly expressed in our primary sensory neurons. And this sensory neurons is so-called the dorsal root ganglia neurons. Not only itch, the dorsal ganglia neurons will, I mean, will control different somatosensations, including itch, pen, temperature, even the mechanical sensory. Interesting. Yeah, and this primary sensory neuron will combine these signals and then transmit to the internal neurons in the spinal cord and then to our brain. Wow, OK, one more time. Dorsal root ganglia, which neurons, OK, and that's located in the basal ganglia? Yeah. OK, OK. And so this is very more limbic structure, lower brain structure, not higher cortex structure, lower brain structure. So more older structure, this response. So both mechanical touch, temperature, pain, and itch, somatosensory, the combination of all of those is in this dorsal root. So, yeah, OK, sorry. So dorsal ganglia, the neurons, it's a heterogeneous, a heterogeneous. And prior studies have known that the small diameter neurons will mediate itch and pain. The large diameters will control our, such as the mechanical. As for the temperature, it depends on the expression of different temperature related, such as ion channels. And as I mentioned, this small diameter neurons will control nearly all of the non-ceceptions, including pain, itch. OK, OK. And then how are we learning that the dorsal root ganglia, how do we know that that center is responsible for somatosensory? For example? Yeah, how do we know that that area is responsible for the somatosensory? Do we do neural mapping, neural imaging of that center when, you know, when you poke or when you scratch and you see that area have activation? OK, if I understand it correctly, you mean, how do we characterize this sensory neuron? For example, each neuron indeed controls each sensation. OK, actually, there are many technologies that can help us do that. For example, the single cell aren't sick. Yeah, we can pick one single neuron and then sequence their MRA will help us to identify which gene is expressed in this neuron, this single neuron. If this neuron expressed a well-known itch receptor, such as the mosquito itch receptor, we have known that this neuron could mediate the mosquito induced itch. By the way, the mosquito induced itch is medied by the histamine released by the mast cell. I mean, the mosquito, the bite of the mosquito, such as maybe some organic acid, acid, or stimulate our immune cells, such as the mast cell, and the mast cell then release the histamine. And the histamine, it's a true proietrogen, I mean, the itch-causing compound. It will activate its receptor, the histamine receptor, especially the H1 receptor and H4 receptor expressed in the small diameter DRG neurons. So, yeah, back to this question. If we sequenced the gene expressed in the single neuron, and we found that this neuron expressed the histamine H1, it's a H4 receptor, so we have reason to believe this neuron could mediate the histamine induced itch. Yes, okay, okay. This single cell aren't sick is powerful. And so, we're doing single cell RNA sequencing on the basal root ganglia, or on the dorsal root ganglia. And that gave us the understanding that it expresses specifically for itch. Actually, yeah, yeah. Actually, as I mentioned, it can help, it can tell us whether this neuron could indeed express each receptor or not. But the direct question is that whether this receptor expressed in this neuron is functional. So, we need to do some other experiments to help us to demonstrate or characterize whether this neuron is indeed functional in the, for example, each transmission. And to achieve this, yeah, as I mentioned, we can do many different kinds of experiments. One is the calcium imaging. Because if the neuron is activated, the intracellular calcium will be increased either through the extracellular calcium influx or the release of the calcium from the intracellular part, the ER part. And I mean, the calcium is released from ER to the cytoplasma. The intracellular increase of the calcium will activate this neuron. You know that the neurotransmitter release is dependent on the calcium increase. So, the calcium imaging, I mean, this experiment will help us to test whether this neuron is indeed functional in this process. For example, I can buy the histamine, I mean, the pure histamine compound and then treat it as the neurons. If this neuron is expressed a functional histamine receptor to mediate each, the application or the administration of histamine will activate this neuron. So, this neuron, I mean, the intracellular calcium will be increased. If we use the one calcium indicator to help us to distinguish whether the intracellular calcium in this neuron is increased, we can distinguish this. Interesting. Intracellular calcium increase, okay, means that it's expressing to... It's activity of this neuron. Okay. Okay, so that's one in single cell RNA sequencing is another part of... Actually, it is a two-distinguished part. Two different ways to... One, the single cell RNA-stake, it's demonstrated the expression of the receptor. The calcium imaging or the electrophysiology is demonstrated that function of the receptor or this neuron, both the expression and the function. I like that, yeah. The expression and the function gives you the knowledge that that's what's going on, yeah. How about... Let's talk about this from the explanation of GPCR, G protein-coupled receptors. Okay, so apparently there's lots of them on the outside of every cell. Do we know about how many on the outside of every cell? Lots. You know the numbers of GPCRs in our body? Yeah, on the... But let's do try every cell, how many GPCRs? No, not every cell. Not every cell. Which cells have GPCR and which ones don't? It depends. As I mentioned, if this receptor could mediate, such as each PEN, and this GPCRs may be exclusively expressed in the primary sensory neurons, the DRG, the dorsal rotor ganglia neurons, if this receptor could mediate the immune reaction, these GPCRs, these receptors may be expressed in the immune cells, such as the mast cell or microphage. It depends. Okay, but all neurons and glia cells have GPCR receptors? Hmm... Or a lot do? Or... Sorry, okay. How many of the brain cells have GPCR receptors? I think nearly all the neurons... Nearly all neurons. Nearly all neurons could express GPCR, but not all of the GPCRs. Okay, but not all. In our body, there are nearly 800 GPCRs. Yes, okay. There are some identified GPCRs. I mean, the function is known and some others are often GPCRs, means their endogenous ligands are unknown, so-called often GPCR. For your question, I think nearly all of the neurons, the brain neurons could express several GPCRs, for example, the glutamate receptor, but not all of the GPCRs. Okay, okay, okay. Okay, and then when we look at the GPCR receptor, this is something that is about 40 or 50% of all FDA drugs are targeting GPCR receptors. So this is a big field. People care a lot about being able to target molecular compounds to GPCR receptors. So how do you know what GPCR receptors are related to itch? Is that what we were talking about earlier with the dorsal root ganglia that those cells have GPCR receptors for itch? Yeah, is that what we were talking about earlier with the... So your question is, how do we characterize a receptor as each receptor? Yes. Okay, as I mentioned, firstly, in the expression level, it should express, if this receptor is each receptor, it should express in the primary sensory neural, the dorsal root ganglia neural. After that, we need to demonstrate their function, or its function in each pathway. Expression function, yes, and specifically the dorsal root ganglia. Okay, so then you are always targeting dorsal root ganglia GPCR receptors? Yeah. That's your... Okay, because that's always where itch is. Yeah. It's going to be... Okay, okay. Cholestatic disease. Cholestasis. Cholestatis. Cholestasis. Obstructing the flow of bile from the liver. Yeah. Okay, so bile from our liver is what tells us to itch? Okay, so, yeah, you know that in the physiological condition, the bile will reach to the intestine from the liver, especially in the doodino, which is a part of small intestine. And the bile, such as the bile acids, will help us to digest the food. But there is a condition of the disease called cholestatis. It means there is some blockage, so the bile cannot reach to the intestine, but accumulates in the liver. And through the systemic circulation, this accumulated bile, for example, the bile acids, the bilirubin, our compounds contained in the bile, will reach to our body tissues through the systemic circulation, such as the serum or skin. And the major symptom of the cholestatic patient is the itch, the severe itch. I mean the chronic itch over six weeks. And but the magnesium is still unknown. But actually, 2000 years ago, a Greek physician found that, or hypothesized that, maybe some compounds contained in bile caused itch from his clinical observation. So we hypothesized that maybe some compounds contained in bile is the itch-causing compound. OK, and then compounds in bile are itch-causing. OK, and then our itch-causing compounds. And if the bile builds up in the liver and doesn't, if the flow is obstructed, like in cholestasis, then the itch just goes to chronic itch happens with the buildup of bile. OK, so bile acids, as I mentioned, if we accumulate in the liver through the systemic circulation, it will reach to other body tissues, including skin. And we hypothesized that the elevated levels of bile acids maybe trigger the itch. But the question is that, what's the receptor that emitted this itch? We don't know. OK, OK, buildup of bile acid in the liver causes chronic itch. OK, so the obstructed flow, so if bile was flowing, then we wouldn't be itching. OK, it's an interesting point. As for the, actually, there are several therapies for the cholestatic itch. One of them is a resin. It actually is an iron resin, so-called cholesteremia. It's a strong iron resin. I mean, it will absorb the bile acids to form the insoluble complex that's then secreted from our body tissue. And the patients, after usage of this cholesteremia, this itch is released. It's decreased. I mean, decreased. So we hypothesized that the decreased bile acids caused the decreased itch symptom. So maybe the bile acids is the itch causing compounds. Yes, OK, OK, OK. So now we also figure out that there's a process with the bile acid that then also is when it induces the bile acid compound inducing itch. But then we also are trying to figure out how, with chronic itch, to block the GPCR receptors so that in the dorsal root ganglia, so that I don't chronic itch. So you want to make a molecular compound to block the GPCR receptor so that I don't itch. Exactly. To achieve this, we need to know the exact of the receptor that immediate this itch. So our lab are interested in this question. And as I mentioned, this year's study have known that most of the itch receptors are GPCR. So we focus on the GPCR, especially the orphan GPCRs, expressed in the dorsal root ganglia neurons. So these orphan GPCRs should be a candidate. Maybe the candidates that immediate this itch. So we analyze the sequence data of the human dorsal root ganglia neuron. And we found several orphan GPCRs that are highly expressed in this DRG neurons. I mean, in the human DRG neurons. So these orphan GPCRs, as I mentioned, should be the candidate that immediate this itch. So when we found this, firstly, we used the Bio-X tracks, the Bio-X tracks to test whether the Bio-X tracks could activate these orphan GPCRs. If this receptor, or maybe one or several GPCRs, could be activated by the Bio-X tracks, it should be each receptor, at least a candidate receptor. And actually, we performed this. And we found that the Bio-X tracks could specifically activate one of the orphan GPCRs, very luckily. And we found that it is MRGPR-X4 that highly expressed in human DRG neurons. So the Bio-X tracks is complex. I mean, there are many different compounds, including bio-acids, bilirubin, and some other compounds. So after that, we want to know the exact compound. I mean, the active component contained in the Bio-X tracks that activate this MRGPR-X4, this receptor. So after the chemical separation, such as the mesospectral, you know that, the mesotractal, or NMR, and we identified it is bio-acid. It's the active component to activate this receptor. Yeah. OK. And then you have to figure out out of 2,000 molecular compounds, which one is going to do the blocking of the GPCR receptor. So you have to run 2,000 of these experiments to see. Actually, when we found that MRGPR-X4 by combining other experiments, we have demonstrated that this receptor is each receptor that mediate the bio-acids-induced colostatic-H in human. So after that, we want to know or we hypothesis that if we could find a compound that specifically blocked this receptor, it should be a drug candidate for each symptom. And actually, we have did this. We screened nearly 2,000 compounds and we have found some candidates. And we think we can find a compound that can block this receptor. But it's not enough, you know, that if we want to further develop this compound from bench to clinical, we need to demonstrate different properties of this compound, such as the potency affinity toxicology. Yeah. So if we found this compound, we need to collaborate with such as chemical groups to perform the chemical modulation of phantune the structure of this candidate to get a potent one, especially specificity. The specificity is very important because we don't want to get other side effects. And if we found this potent compound, I mean the antagonist of this receptor, it should be a best candidate for this each. OK. So then it could be that the about 200,000 people in the USA per year, and I don't know how many worldwide, probably millions of people in the worldwide, that have a cholestatic disease can then potentially use a pharmacological aid in order to prevent their chronic itch from happening. OK, so this is one of the health outcomes of your scientific research. Yeah. Actually, there are no efficient therapy for this treatment, I mean for this cholestatic itch. The traditional method used the cholesteroamine, as I mentioned, but it will cause severe constipation. And because of this test, the severe test, the patients found it unplatable. And yeah, so we think if we find a drug, especially a drug candidate, it should be very efficient for this each symptom. In addition to treating itch, where else could science like this help us? OK. In addition to each, there are many different sensory somatosensations, such as the pain, or temperature, or the mechanical. The pain is also a severe one. So if we find the pain, I mean, the specific receptor that immediate pain, we can treat the pain symptom with the similar strategy. Like when I have a very severe surgery and I have several weeks of severe pain that we could block the GPCR receptor for pain? Yeah, yeah. The traditional method is such as the morphine. But it has a severe side effect, such as the addiction. High addiction. High addiction. Because there are many morphine receptors expressed in our brain. But if we cannot achieve the specificity, it will cause a severe side effect. For each receptor, as I mentioned before, it is specifically expressed in the Dothraut ganglion neurons. If we find a candidate or antagonist of this receptor, supposedly it will not influence our CNS, the central nervous system, because it can specifically target to this receptor, but not other receptors. OK. So targeting pain very specifically, rather than in the whole numbing of the whole. Yeah. Yeah, OK. OK. Get some point. Yeah, exactly. OK. And maybe even, yeah, temperature. Maybe even the mechanical. OK, OK. OK. OK. Now, what about where do you see your work here at the lab? Where do you see your work going with, you think then, do you need to partner with a pharmacological institution to help you develop the molecular compound for you to actually be able to go and deliver that to the GPCR receptors to block the itch for the chronic itch patients? Exactly. Actually, our work, you know, that in the lab to demonstrate a principle. I mean, we have found the molecular magnetism of cholestatic itch, for example. We have this screened antagonist. And we believe that many pharmaceuticals also want to treat this itch, because it has a big market. So it can also, to this compound, these companies can also target this itch receptor to treat this itch. I mean, find the antagonist. Do you know what it would look like for a lab that found the molecular mechanism of itch, of a chronic itch, to work with a pharmacological company? Like, what do you do? Do you say, here's our research paper. Will you guys make the molecular compounds and then continue helping us fund this project and we collaborate on it? And then we own, we split the IP, the intellectual property. How does it work if that happens? Actually, we can collaborate with some pharmaceuticals. And we can also build up our own pharmaceutical to develop the compound to the clinical trial. Yes, yes. OK. I'm curious what the split in ownership is or what the funding is like. Do they help fund the lab? If you guys have really good research that they want to use, that's an interesting question. The relationship between a pharmaceutical company and a lab that's doing research. What would be a ideal neuroscience tool for you, let's say 50 or 100 years down the line, where we're doing everything that we want to do with the brain? What would that tool look like? OK. The question is, what is the most efficient tool in neuroscience? Yeah, and 50 or 100 years down the line, the future. Even for the future. Yeah, yeah. What would that look like? What would that tool look like? I think it may be called the optogenetics, you know, the channel reduction. If we can express a channel reduction, actually it's ion channel, in the neuron, we can just use a light to stimulate this neuron, to activate or deactivate this neurons activity. So if we want to treat some disease caused by the sensory, I mean the neuroscience, the nervous system, we can express this optogenetic related ion channels in the brain, and use a light to activate or deactivate the neurons. So I think the optogenetics is powerful. Yeah, agreed. Optogenetics is a massive one. OK, OK. How about on a global collaboration level, how can we increase people around the world working together? Oh, it's interesting. Honesty is important for the collaboration. Yeah, and we need to share our data with each other, but not hiding them. Yeah, and besides that, I think the policy is important. I mean, the government, the policy is important for the collaboration, especially from different countries. Yeah, yeah. Honest data, more clear scientific communication and collaboration channels, and then just the overall, I guess governmental, but also company-wide collaboration across the world. How about as we go into this exponential technology era and the 21st century, what is a skill that young people should know so that they can be highly effective in the world? OK. It's hard to say. I think, firstly, the tool is important for the technology. I mean, the tool is important for one field to achieve the hard problem or the question. So maybe the tool development is important. Yeah, yeah. Oh, I like that answer. Young people going into the new ages should be focused on tool development. I like that answer, especially because then the tool can then have other people from around the world begin using the tool and then have more creativity, more science. Yeah, yeah, yeah. I like that. What about we find ourselves being born onto this planet orbiting the star? There's 8 billion of us here, 100 billion potentially lived and died before us to build the world. What is the purpose of the human experience? What's the meaning of life? OK. You mean the purpose of the human being? Yeah. OK, it's very interesting to survive. And I think for the better survival, the better life is important for the human beings. OK, yeah. A constant process of bettering the human experience. Yeah. What do you think about consciousness? What is consciousness? Oh, it's very complex. It's very, very complex. I think it depends not only on the nervous system, it may be enclosed different symptoms. The nervous system, immune system, the behavior and the psychologist. To my knowledge, I don't think it's a clear study to demonstrate what is consciousness. Yeah. Do you think we have free will? Sorry? Do you think we have free will? Free will. Oh, OK. Maybe. But, yeah, we still don't know the magnet, OK. It's hard to say. Yeah. The consciousness is very complex. Yeah. What do you think is the role of love in life? Sorry. What do you think is the role of love in life? Oh, it can allow, will encourage yourself to pursue what you want, to pursue your life, OK. And for me, as I mentioned, it can help to release, especially when I was in a depressed, kematon or upset condition, the love can help us to stand up and move on, move on. Yeah. Love can give us something every day when we wake up to look forward to achieving every day, falling in love with what you do. And given that our computational capacity has been increasing so fast and our ability to make simulations of biological systems and all these types of things, do you feel like our life is a simulation? Yeah. I think it is a simulation, so complex, OK. It depends on the correlation. I mean, it depends on the correlation between different systems. Yeah. What do you think is the most beautiful thing in the world? Love. Yeah. I think love is the most beautiful thing in the world. And love, why? Everything. Why? Yeah, why? Why is it that? I mentioned it's the source of power. Yeah. Yeah. Yeah. I love this. I mean, this has been such a fun conversation. Thank you very much for joining us on the show. OK, thank you. Thank you. Thank you. Thank you. Yeah, it's been such a pleasure learning about the sensory GPCR of itch. We would love to hear your thoughts in the comments below, everyone. Let us know what you're thinking. And have more conversations with your friends, families, coworkers, people online about sensory GPCR, about itch, about fixing chronic itch, about the development of the newest sort of molecular compounds that can help solve some of these major diseases or issues with our bodies. More conversations about neuroscience. Also support youlongleadlab.org, the links in the bio below. Support the artists, the entrepreneurs, the leaders, the organizations around the world that you believe in support us. Simulation, you can find our links below and support us there. And also go and build the future, everyone. Manifest your dreams in the world. Zhongxia Kuala. Happy Mid-Autumn Festival. And also go and build the future. Manifest your dreams into the world. Thank you very much, everyone, for tuning in. And we will see you soon. Peace.