Good afternoon every one.Thanks for coming. Thank you organizers for this opportunity. Before I start my talk, I would like to ask you a simple question. You can see two honey bees here. Can you identify the queen bee?
There’s a worker bee and a queen bee. Can you identify the queen bee? Which one? [Audience] Right one? That’s right. I bet few of you know about why queen bee is queen bee and worker is not because they started life as babies in the form of insect larva and they were looking the same. but now, they look very different. The reason behind this is normally important for the structural development of bees, but also important for our well being and human health. Moving on to my topic, which is “Nature-inspired Cure to the Incurable.” The key word here is cure. What is cure? If you look at the Merriam-webster dictionary, cure means care, derived from a latin word, cura which means a divine god that can protect us from the evil things. So, incurable literally means that diseases are the factors that cannot be taken care of. There are so many incurable diseases known in the world. and as if that’s not enough, we keep inventing new ones because of our lifestyle. but these two diseases you can see,
which is cancer and diabetes have been known since B.C. Are we not caring to cure them? We do, right? We spend a lot of money but still, it’s incurable. Why? When we have a problem, we have to get into the root of the problem what we do right now is treatment. That is the surface. The output, we are treating but the actual underlying cause we are not. Now, we have traveled a long way since B.C. and we now know the information which we did not know long ago.
and that is the genome. Let me introduce the human genome. This is us. We are made from letters. Three billion of them. ATGC. The genome of human is so identical that we can call us one universal genome. Where are these letters in our body? These letters are stacked up in a double helical structure which we all know as DNA. The functional unit of the DNA is called gene, and that has been passed onto the biological system to a genetic code which you see on the right. So there are about 30,000 genes known. Modern technologies help us identify some of the genes which are very sensitive. When there is a problem in those genes, disease can occur. But it also helps us to identify some of the genes which can take care of those problems. These genes are called “guard genes” or “caretaker genes.” Let me introduce the most important caretaker, known as “guardian of the genome” that is p53. Imagine this is our cell.
The cute little smiley, being our cell very happy. And when disease signals happen, what this p53 does is that it starts a machinery to either repair them or arrest them. If there is no hope, then all cells are dead. So what happens when p53 is not present or being blocked? like by the gene E6 shown here? that results in cancer, which is the uncontrolled cell division. In fact, 50% of the cancer is known to be affected by p53. So how can we restore this gene? People have developed many different strategies, and one of the strategies got inspired by nature, from a tiny living organism called bacteria. Why bacteria? Bacteria. If you see the micro environment, it lives in a complex environment filled with infectious agents, like virus you can see here. They want to infect the bacteria by injecting the DNA into that. How does bacteria protects itself? What it has is an immune system called CRISPR-CAS9. CRISPR is a system that can specifically recognize the foreign DNA elements and CAS9 is a DNA repair protein that is shown in the scissor. What happens is that It can specifically target and edit the viral DNA element to take away the virus infection. People started using this technology for their purpose and there have been many CRISPR systems developed. One of the CRISPR system called E6 CAS9 was developed by researchers in North Carolina. This oncogene called E6 could arrest or block p53. What they did is that they developed a system to cut the blocking agent to restore the natural guard. This is good. This is not only applicable for p53 restoration, but many disease-causing genes could be edited now. For example, HIV, muscular distrophy…and so on. But there’s a problem. Not many people like their gene to be modified when they have a disease. There’s also another layer that can control the gene expression. That is called epigenetics. So what is epigenetics? Epigenetics is a process that lies above the genome to switch off or on the gene. Off means silenced, and on means expressed. Now I said a word called “expression.” You might have heard this expression called “gene expression.” What is that? We all know DNA, the form of double helical structure, as shown here. But it’s very long, about 20 meters long. So how are they located inside our cell? It’s because they get bind around the natural protein called histones, shown in yellow here. In this way, they bind around the histones to be packaged. This position of histones determine whether the gene is silenced or expressed. For example, if this is the gene-coding DNA, what happens is that this is how the silenced gene looks like. What determines the position of histones is the tiny marks around or over the genome called silence marks, shown as the red buttons there. Can you read what’s in there? This is an “off” gene because we can’t read it. What is “on” gene? Can you read them now? This is gene “on.” There are some marks shown in green here, which can cause expression by unwinding the DNA from the histone protein. These marks are called “expression marks.” Previously, I asked you a question. Why a worker bee looks like a worker bee and queen bee looks like a queen bee. Now is the time for the answer. As I told, it started their life as bee larva but it became worker or queen. Why? Because there is a strange rule in the bee world that after some time, some set of larva are fed with worker jelly and the other set of larva are fed with royal jelly. You can see the royal jelly below the yellow protein. What is the secret ingredient in royal jelly? It’s the small molecule called “fatty acid.” This small molecule acts as a switch to silence the silencing mark which is shown in the red. When this happens, the gene gets expressed and queen factors get released to make the queen bee. So that’s the answer. That’s the story of queen bee. But that doesn’t stop there. We, humans, also have the same situation. Several disease-causing episignals like environmental intoxicants, stress, smoking or drinking all of them are very bad to our body and it leaves a mark on not only us, but also our child and even our grandchild. For some of you who have really corrupted the system enough and are afraid to be blamed for the child or grandchild, please don’t worry. Tell them that it is reversible. There is a way to reverse the bad epigenetic mark. How can we do that? Again, there are several ways to do that. But one method that both clinicians and patients prefer is to use a simple small molecule. This small molecules acts as a switch to remove the silencing epigenetic mark. Imagine this is the genome of our diseased cell. and small molecule switches can enter the genome and affect the silenced gene. As you can see, the natural guard, p53, got restored. but there are also other genes which are not supposed to be disturbed like the normal genes; those also got activated. The issue is selectivity. This is the key area where scientists want to develop a way to target the epigenetic switches to specific places. So how can we do that? Talking about specificity, I will introduce the sequence-specific DNA binder, a small molecule called Pyrrole-Imidazzole Polyamides, or PIPs. This PIP was discovered by Prof. Peter Dervan of CalTech from the naturally occuring antobiotic distamycin from bacteria and the aminoacid histidine. Pyrrole is shown as the blue circle and imidazzole is shown as the red circle. The position of pyrrole and imidazzole can read specific sequences or letters. For example, pyrrole pyrrole can read either A or T, imidazole pyrrole can read GC, and so on. Good thing is that this small molecule can enter our cell and bind to the DNA. So what we did in our laboratory, led by Prof. Sugiyama, is that we combine the selective DNA binder which I show you now, PIP with the epigenetic-activating small molecule in this case a small molecule called SAHA shown as a star there. We combine them both to make a nature-inspired genetic switch called SAHA-PIP. In nature, gene expression is controlled in both genetic level and epigenetic level. Now, we have a small molecule which can access both the genetic environment and epigenetic environment. So what this small molecule can do. We made several SAHA-PIPs. I don’t have time to discuss them all. But I will say three major SAHA-PIPs that we discovered to have bioactivity. You can see that the red circle is positioned at various places These SAHA-PIPs are expected to bind to different DNA sequences. We tested the bioactivity of SAHA-PIP in human skin cell and one SAHA-PIP actually activated the stem cell related gene called OCT4. This is a key gene that is important for stem cell development. Another SAHA-PIP did not activate OCT4 but activated an entirely different set of genes particularly a key gene called PIWI whose absence can cause infertility. Another SAHA-PIP activated a gene called PAX6 which very important for eye development. As you can see, these genetic switches are much more selective than the normal small molecule switches. We also activated some of the guard genes. For example, HIV-1 silencing gene called MX2 got activated by one different SAHA-PIP. And, autism. The disease is popular these days among children because of bad environments. Many people now have autism. The gene called CNTNAP2 which can suppress autism also got activated. and the gene that can suppress obesity also got activated, which is MX2. Let me caution you that at this moment, we are using these SAHA-PIPs only as research only tool. But our ultimate aim is to use them for the clinical application. For that, we have to do many considerations for the design of SAHA-PIP because epigenome is very complex. It’s not so simple as how it is described in the form of a green or red button. But I am confident that at some point, we can develop the small molecule to be used for the clinical application. To conclude, I would like to emphasize that we started to know what causes the disease by discovering the DNA double helical structure in 1950. and in 2001, we made a very important achievement which is the completion of the human genome project. and after that, we have been making discoveries so fast that discovery has become like daily news. and I’m sure that with the nature-inspired technology, like CRISPR-CAS9 and DNA-based epigenetic switch, and others cure can come anytime soon. because I strongly believe in the saying that nothing, I mean nothing cures like nature. thank you. [audience applause]