Cell and Molecular
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The research in cellular and molecular biology is one of the major research areas in our department. Our works have covered various aspects of molecular biology, neurobiology, developmental biology, molecular endocrinology, functional genomics, stem cells and lipodomics, as well as plant biochemistry and tissue culture.

Stem cell biology and gene regulation
Currently, two groups are focusing on stem cell technology and aim to understand the molecular mechanisms involved in the maintenance of pluripotency and self-renewal capability of embryonic stem (ES) cells and organogenesis using several vertebrate models. One such excellent model for vertebrate development is the fish medaka ( Oryzias latipes). The group of A/P Hong Yunhan is working to develop pluripotent ES cell lines and gene targeting technology in this fish as a biomedical model system complimentary to the mouse, while also studying why/how these ES cells maintain their pluripotency and undergo differentiation. In addition, studies are being carried out to investigate the specification and development of germ cells and to establish the possibility and conditions for full recapitulation of spermatogenesis in vitro. The group of A/P Chan Woon Khiong is studying how human ES cells maintain their pluripotency. They also use zebrafish as the model system to study how thyroid receptors and fushi-tarazu factor-1 nuclear receptors regulate organ formation during embryonic and early larval phase, and the process of metamorphosis. Transcriptional regulators such as activators, repressors and chromatin remodeling complexes play important roles in regulating gene expression. These are studied by the groups of Dr Ng Huck Hui and Dr Philippa Melamed. The former group focuses on understanding the functions of transcriptional regulators in stem cell and cancer biology, while the latter group works in the field of molecular endocrinology. Both groups undertake diverse experimental approaches to dissect the functional roles of these regulators, including chromatin immunoprecipitation to identify direct targets, RNAi for genetic analysis and proteomics to identify interacting partners, in an attempt to probe the molecular mechanisms underlying pluripotency, tumorigenicity (Dr Ng) and hormonally-induced gene regulation (Dr Melamed). The group of Dr Ng is trying to understand the global regulatory networks at both DNA and protein levels in different cells, which would provide an understanding of the specification and control of different cell fates and cell types. The group of Dr Melamed, is seeking to understand the mechanisms of hormonal induction of gene transcription and chromatin remodeling, and is currently focusing on the pituitary hormones that regulate reproduction, and the estrogen receptor.

Cell signaling and molecular mechanisms of gene function
The phosphorylation of specific proteins on Ser/Thr residues preceding proline is thought to be a major cellular signaling mechanism, but little is known about how the phosphorylation actually regulates protein function. Recently, characterization of the novel peptidylprolyl cis/trans isomerase by Dr Liou Yih Cherng demonstrated a new aspect of this post-phosphorylation regulation mechanism. However, the ways in which the isomerase and associated proteins catalyze the conformational change and execute their biological function is still not well understood. The isolation of the phosphorylated Ser/Thr-Pro specific prolyl isomerase has implicated a new signalling mechanism, where prolyl isomerization catalyzes conformational changes in proteins, following phosphorylation, to regulate protein function. The group led by Dr Liou is researching the mechanisms through which the isomerases dynamically catalyze the cis/trans conformational changes of pSer/ Thr-Pro motifs and how this conformation change affects the function of its target proteins.

The group of Dr Low Boon Chuan was the first to discover the BNIP-2 and BPGAP family proteins that utilize the conserved BCH domain as important regulators for cell signaling. BNIP-2 links receptor tyrosine kinases to small GTPases, while BPGAP directly regulates small G protein signaling; both of them connect and converge to cytoskeletal network regulation and harbor a unique protein-protein interaction module. Bioinformatics analysis has helped discover at least 50 novel proteins with the conserved BCH domain, supporting its significance in various cellular processes, which include cell death, cell morphology, cell migration and endocytosis. One member, BNIP-H has been identified by others as the protein responsible for a type of ataxia motor disorder. The signature motif that distinguishes BCH domain family from other related domains has been identified while its structural determination and detailed functional mechanisms are underway.

Lipidomics
The goal of the lipidomics group, led by Dr Markus Wenk is to use systems-level scale analysis of membrane lipids (lipidomics) as a novel tool in the global analysis of biological systems. They are primarily interested in the metabolism of membrane signaling lipids such as the phosphoinositides (phosphorylated derivatives of phosphatidylinositol).

Neurobiology, neuronal development and apoptosis
The degenerative mechanisms of dopaminergic cells in Parkinson's disease (PD) remain elusive even after many years of research. Many have hypothesized that cell deaths in PD are via apoptosis and specifically via the mitochondrial-mediated apoptotic pathway. Using molecular cell biology and proteomic approaches, the group of A/P Lim Tit Meng has identified several proteins that are involved in neuronal degeneration, such as PD. Their goal is to uncover the alternative apoptotic pathways and the detailed mechanisms that take place in these neurons. They are currently studying the role of alphasynuclein and the effects of neurotoxins in inducing neuronal apoptosis. They are also examining the differentiation of dopaminergic neurons, with the long term aim of developing cell replacement/ gene therapy for PD. The group of A/P Sheu Fwu Shan focuses on the molecular basis of neural plasticity, learning and memory. To test a cellular effect of rodent neurogranin (Ng) oxidation as compared to Ng phosphorylation, they have developed a cell model capable of stable expression of Ng using the Tet-On system, to determine whether Ng oxidation regulates intracellular calcium level. Their results suggest that Ng oxidation plays a significant role in intracellular Ca2+ homeostasis, essential for the activated signaling networks in learning and memory.

Comparative biochemistry
As a centre of fish trade, Singapore has access not only to tropical fishes in Asia but to fishes from all over the world, providing a unique opportunity to study the Asian freshwater stingray (Himantura signifier) and the Amazonian freshwater stingray (Potamotrygon motoro). This research program, led by Prof Ip Yuen Kwong, has expanded to include all six species of lungfish. They have developed procedures to induce aestivation in African lungfishes on land, which facilitate studies on metabolic rate reduction, control of ornithine-urea cycle, regulation of ammonia production and suppression of activities in the central nervous system.

Plant molecular biology developmental physiology and tissue culture
The molecular developmental biology of plants research group, led by A/P Kumar Prakash focuses on functional analyses of selected cDNAs, particularly those involved in regulation of vegetative shoot development, focusing primarily on the regulation of shoot development in plant tissue culture. Paulownia, a fast-growing timber tree species, Arabidopsis and Petunia are used as experimental systems. Additionally, RAPD markers for plants are being studied and it is hoped that the results of these long-term research projects will contribute to a better understanding and regulation of organogenesis in plant tissue culture.

The groups of A/P Yeoh Hock Hin and Dr Ong Bee Lian are targeted at understanding cyanogenesis in cassava ( Manihot esculenta Crantz) and its related enzyme (linamarase) for improving safety in cassava consumption. A recent interest is on the application of cassava starch as biomaterial for tissue scaffold. They are focusing on isolating linamarase whose properties have allowed the development of sensitive procedures for evaluating the cyanogen content (linamarin) in cassava roots as well as cassava-based foodstuffs. In addition, cyclic somatic embryrogenesis of cassava has been developed as a tool to facilitate investigation of cassava cyanogenesis and starch biosynthesis. They are also interested in understanding the physiological and biochemical responses of tropical plants to changes in the environment, especially changes in light and water availability to plants.

In the Plant Developmental Physiology lab, led by A/P Loh Chiang Shiong, the long-term goal is to understand the factors and mechanisms governing the morphogenesis of plants. In addition, they aim to regulate the growth and development of plants in culture and to study the possible applications. They utilize plant cell and tissue culture techniques, fluorescence and confocal microscopy, flow cytometry and patch clamp. They discovered that Rare Earth Elements have some unusual effects on the growth and development of a model plant Arabidopsis thaliana and REEs were found to promote floral initiation and reproductive growth but had no effect on vegetative growth of the plant. As REEs are nonhormonal, the idea of developing non-hormonal flowering promoting agents is proposed. In addition, they successfully developed somatic embryogenic cultures from cassava ( Manihot esculenta) and its related species. Using such repetitive somatic embryogenic cultures, they obtained mutant lines with different starch biosynthesis and cynogenic content. Such systems will allow manipulation of biosynthesis of cynogenesis and starch biosynthesis in the future.