An Explorer of Chemical Biology of Plant Natural Products in Southwest China,Xiaojiang Hao

Xiaojiang Hao,who obtained Master Degree from Kunming Institute of Botany(KIB),Chinese Academy of Sciences(CAS)in 1985,and Doctor in Pharmacy degree in Pharmacy from Institute for Chemical Research,Kyoto University,in 1990,was born in Chongqing in July,1951.In 1991,he returned to KIB,CAS,as an Associate professor and served as the chair of the Department of Phytochemistry.In 1994,he was promoted to a full professor at the current institute.He served as the Deputy Director of KIB and the Director of Open Laboratory of Phytochemistry from 1995 to 1997,and the Director of KIB from 1997 to 2005.Professor Hao has published more than 450 peer-reviewed SCI papers,which have been cited over 6000 times.He has obtained one PCT patent and 23 patents in China.Due to his tremendous efforts,one candidate drug,phenchlobenpyrrone,has entered the Phase II clinical trail for the treatment of Alzheimer’s disease.Moreover,he won the First Prize of Natural Sciences in Yunnan Province for three times,and Ho Leung Ho Lee Fund Science and Technology Innovation Award in 2017.

Integrated Systems Biology and Chemical Biology Approach to Exploring Mechanisms of Traditional Chinese Medicines

After thousands of years of development, traditional Chinese medicines （TCMs） have evolved into a complete scientific system characterized by multiple components, targets, and pathways, which mediates numerous pharmacological activities and efficacies. The development of ＂-omics＂ technology, including systems biology and network pharmacology, has enabled the illustration of TCMs from a more systematic view. Although the network adequately reflects the overall philosophy of TCMs, its complexity hinders the relevant research to a hover. In addition, the strategies involved appear to be in contrast to the original concise and efficacious disease therapy oriented focus on classic Chinese material medica （CMM）. Based on the established holistic view and reductionism, in this review, we discuss an integrated systems biology and chemical biology research approach that will facilitate and accelerate the understanding of the mechanisms of TCMs. Furthermore, we are optimistic that it will elucidate the associated interactions between active natural products and their targets, and ultimately improve the strategies for complex disease therapies.

Scoping biology-inspired chemical engineering

Biology is a rich source of great ideas that can inspire us to find successful ways to solve the challenging problems in engineering practices including those in the chemical industry. Bio-inspired chemical engineering(Bio Ch E)may be recognized as a significant branch of chemical engineering. It may consist of, but not limited to, the following three aspects: 1) Chemical engineering principles and unit operations in biological systems; 2) Process engineering principles for producing existing or developing new chemical products through living ‘devices';and 3) Chemical engineering processes and equipment that are designed and constructed through mimicking(does not have to reproduce one hundred percent) the biological systems including their physical–chemical and mechanical structures to deliver uniquely beneficial performances. This may also include the bio-inspired sensors for process monitoring. In this paper, the above aspects are defined and discussed which establishes the scope of BioChE.

Fungi as chemical industries and genetic engineering for the production of biologically active secondary metabolites

Fungi is somewhere in between the micro and macro organisms which is a good source of producing biologically active secondary metabolites.Fungi have been used as tool for producing different types of secondary metabolites by providing different nutrients at different laboratory conditions.The fungi have been engineered for the desired secondary metabolites by using different laboratory techniques,for example,homologous and heterologous expressions.This review reported how the fungi are used as chemical industry for the production of secondary metabolites and how they are engineered in laboratory for the production of desirable metabolites:also the biosynthetic pathways of the bio-organic-molecules were reported.

Chemical probing reveals insights into the signaling mechanism of inflammasome activation

Caspase-1-mediated IL-1β production is generally controlled by two pathways. Toll-like receptors （TLRs） recognize pathogen-derived products and induce NF-KB-dependent pro-IL-1β transcription; NOD-like receptors （NLRs） assemble caspase-l-activating inflammasome complexes that sense bacterial products/danger signals. Through a targeted chemical screen, we identify bromoxone, a marine natural product, as a specifc and potent inhibitor of the caspase-1 pathway. Bromoxone is effective over diverse inflammatory stimuli including TLR ligands plus ATP/nigeri- cin, cytosolic DNA, flagellin and Bacillus anthracis lethal toxin. Bromoxone also efficiently suppresses easpase-1 acti- vation triggered by several types of bacterial infection. Bromoxone acts upstream or at the level of the inflammasome in a transcription-independent manner. Bromoxone also inhibits pro-IL-1β expression by targeting components up- stream of IKK in the TLR-NF-kB pathway. The unique dual activities of bromoxone are shared by the known TAK1 inhibitor that specifically blocks Nalp3 inflammasome activation. Hinted from the mechanistic and pharmacological properties of bromoxone, we further discover that several known NF-KB inhibitors that act upstream of IKK, but not those targeting IKK or IKK downstream, are potent blockers of different NLRs-mediated caspase-1 activation. Our study uncovers a possible non-transcriptional molecular link between the NLR （Nalp3）-mediated inflammasome pathway and TLR-NF-kB signaling, and suggests a potential strategy to develop new anti-inflammatory drugs.

Isolation and characterization ofβ-transducin repeat-containing protein ligands screened using a high-throughput screening system

β-transducin repeat-containing protein(β-TrCP)is an F-box protein subunit of the E3 Skp1-Cullin-F box(SCF)type ubiquitin-ligase complex,and provides the substrate specificity for the ligase.To find potent ligands ofβ-TrCP useful for the proteolysis targeting chimera(PROTAC)system usingβ-TrCP in the future,we developed a high-throughput screening system for small moleculeβ-TrCP ligands.We screened the chemical library utilizing the system and obtained several hit compounds.The effects of the hit compounds on in vitro ubiquitination activity of SCFβ-TrCP1 and on downstream signaling pathways were examined.Hit compounds NPD5943,NPL62020-01,and NPL42040-01 inhibited the TNFα-induced degradation of IκBαand its phosphorylated form.Hence,they inhibited the activation of the transcription activity of NF-κB,indicating the effective inhibition ofβ-TrCP by the hit compounds in cells.Next,we performed an in silico analysis of the hit compounds to determine the important moieties of the hit compounds.Carboxyl groups of NPL62020-01 and NPL42040-01 and hydroxyl groups of NPD5943 created hydrogen bonds withβ-TrCP similar to those created by intrinsic target phosphopeptides ofβ-TrCP.Our findings enhance our knowledge of useful small molecule ligands ofβ-TrCP and the importance of residues that can be ligands ofβ-TrCP.

An atypical ubiquitin ligase at the heart of neural development and programmed axon degeneration

The degeneration of nerve fibres following injury was first described by Augustus Waller over 170 years ago.Initially assumed to be a passive process,it is now evident that axons respond to insult via regulated cellular signaling events resulting in their programmed degeneration.Pro-survival and prodegenerative factors have been identified and their regulato ry mechanisms are beginning to emerge.The ubiquitin system has been implicated in the pro-degenerative process and a key component is the ubiquitin E3 ligase MYCBP2(also known as PHR1).Ubiquitin E3 ligases are tasked with the transfer of the small protein modifier ubiquitin to substrates and consist of hundreds of members.They can be classified as single subunit systems or as multi-subunit complexes.Their catalytic domains can also be assigned to three general architectures.Hints that MYCBP2 might not conform to these established formats came to light and it is now clear from biochemical and structural studies that MYCBP2 is indeed an outlier in terms of its modus operandi.Furthermore,the unconventional way in which MYCBP2 transfe rs ubiquitin to substrates has been linked to neurodevelopmental and pro-degenerative function.Herein,we will summarize these research developments relating to the unusual features of MYCBP2 and postulate therapeutic strategies that prevent Walle rian degeneration.These have exciting potential for providing relief from pathological neuropathies and neurodegenerative diseases.

An Approach to Quantify Endomembrane Dynamics in Pollen Utilizing Bioactive Chemicals

Tip growth of pollen tubes and root hairs occurs via rapid polar growth. These rapidly elongating cells require tip-focused endomembrane trafficking for the deposition and recycling of proteins, membranes, and cell wall materials. Most of the image-based data published to date are subjective and non-quantified. Quantitative and com- parative descriptors of these highly dynamic processes have been a major challenge, but are highly desirable for genetic and chemical genomics approaches to dissect this biological network. To address this problem, we screened for small molecules that perturbed the localization of a marker for the Golgi Ras-like monomeric G-protein RAB2：GFP expressed in transgenic tobacco pollen. Semi-automated high-throughput imaging and image analysis resulted in the identifica- tion of novel compounds that altered pollen tube development and endomembrane trafficking. Six compounds that caused mislocalization and varying degrees of altered movement of RAB2：GFP-labeled endomembrane bodies were used to generate a training set of image data from which to quantify vesicle dynamics. The area, velocity, straightness, and intensity of each body were quantified using semi-automated image analysis tools revealing quantitative differences in the phenotype caused by each compound. A score was then given to each compound enabling quantitative comparisons between compounds. Our results demonstrate that image analysis can be used to quantitatively evaluate dynamic sub- cellular endomembrane phenotypes induced by bioactive chemicals, mutations, or other perturbing agents as part of a strategy to quantitatively dissect the endomembrane network.

Development and Application of a Chemical Labeling-Based Biosensing Assay for Rapid Detection of 8-Oxoguanine and Its Repair in vitro and in Human Cells

Living cells are constantly threatened by endogenous and environmental agents that can induce various DNA lesions including 8-oxoguanine(8-oxoG).Increasing evidence has suggested that 8-oxoG is not only a biomarker of oxidative stress,but also a novel epigenetic-like modification involved in transcriptional regulation in mammalian cells.Measurement of DNA damage and repair is useful for both basic research and clinical applications,but current methods for 8-oxoG detection still suffer from some problems such as poor selectivity,time consuming and being expensive.Here,we developed a fast and simple biosensing approach for quantitative analysis of 8-oxoG in DNA,which was based on the selective chemical biotinylation of 8-oxoG in conjunction with biotin-streptavidin enzyme-linked immunosorbent assay.We have also successfully applied this method to achieve efficient detection of the repair activities of DNA glycosylases Fpg and hOGG1 toward 8-oxoG in vitro and in human cells.This newly developed biosensing assay should be generally applicable for rapid detection of 8-oxoG and its repair in other organisms.

Recent advances in target identification by natural product based chemical probes

Natural products have been extensively used to treat diseases throughout human history. These are mainly because natural products normally target biological macromolecules selectively. Target identification could help us to develop new therapeutic agents and discover new biological pathways underlying human diseases. Herein, we highlight some recent examples of using natural products and their derivatives as chemical probes to identify the molecular targets and elucidate mode of action.

Synthesis of NAD analogs to develop bioorthogonal redox system

Three new nicotinamide adenine dinucleotide(NAD) analogs were synthesized,and their characteristics as cofactors for Escherichia coli malic enzyme(ME) and its double mutant ME L310R/Q401C were analyzed.Each pair of the NAD analog and the double mutant showed good orthogonality to the natural pair of NAD and ME in terms of catalyzing oxidative decarboxylation of L-malic acid.Results indicated that molecular interactions between redox enzyme and cofactor could be further explored to generate new bioorthogonal redox systems.

Fluorescent probes for the detection of disease-associated biomarkers

Fluorescent probes have emerged as indispensable chemical tools to the field of chemical biology and medicine.The ability to detect intracellular species and monitor physiological processes has not only advanced our knowledge in biology but has provided new approaches towards disease diagnosis.In this review,we detail the design criteria and strategies for some recently reported fluorescent probes that can detect a wide range of biologically important species in cells and in vivo.In doing so,we highlight the importance of each biological species and their role in biological systems and for disease progression.We then discuss the current problems and challenges of existing technologies and provide our perspective on the future directions of the research area.Overall,we hope this review will provide inspiration for researchers and prove as useful guide for the development of the next generation of fluorescent probes.

Function-Oriented Natural Product Synthesis

Natural products and their derivatives have long been used as medicinal agents,and they still make up a significant fraction of clinically approved drugs.Natural product synthesis provides a rich and unparalleled opportunity to develop new synthetic transformations,conceive novel and general strategies to access complex structures,and study the mechanism of action of bioactive targets.The combination of the tools and principles of chemistry,together with the tools of modern biology,allows us to create complex synthetic and natural molecules,comprising processes with novel biological,chemical and physical properties.This account will illustrate the opportunities that lie at this interface between synthetic organic chemistry and chemical biology by describing a series of examples that we are actively working on in our laboratory at Peking University.We take the inspiration from mother nature to develop new synthetic strategies to achieve the efficient synthesis of complex natural products.In addition,we also conduct chemical biology studies for these bioactive natural products to elucidate their cellular targets and mode of action.Moreover,we further use bioactive natural products to explore new biology and develop novel drug candidates for human diseases,such as cancers and infectious diseases.