Bioscience

LiCl Significantly Improves iPSC Induction

A new discovery in small molecule-enhanced reprogramming made by Dr. Xie Xin’s group in the Shanghai Institute of Materia Medica, CAS/the National Center for Drug Screening was published online by Cell Research on July 5, 2011. After screening ~2000 small molecules, graduate students Wang Quan and Xu Xinxiu discovered that LiCl, a drug used to treat mood disorders, greatly enhances iPSC generation from both MEF and HUVEC. In mouse somatic cell reprogramming, LiCl increases the reprogramming efficiency 5 times for four-factors and 60 times for three-factors. The efficiency of reprogramming was made close to 15%. In human somatic cell reprogramming, LiCl effectively increases the success rate of iPSC generation with single factor (Oct4). The research on mechanism revealed that LiCl’s function in promoting reprogramming does not mainly depend on GSK3b inhibition. Different from other GSK3b inhibitors, LiCl not only increases the expression of the pluripotent gene Nanog, but also enhances the transcriptional activity of this gene. LiCl also changes the epigenetic status of the cells by reducing the protein level of LSD1, a H3K4 specificity histone demethylases. This may also contribute to LiCl's benificial effect in iPSC generation. These results not only provide a straightforward method to improve the iPSC generation efficiency with a small molecule, but also partially reveal the mechanism of reprogramming and provide innovative ways to use the old drugs.

New Progress in Liver Cancer Genome Research

A research project entitled “Collaborative Research on Liver Cancer Genomics” led by Prof. Chung-I Wu, Director General of the Beijing Institute of Genomics, CAS and his scientific team, and Ding-Shinn Chen, Pei-Jer Chen, academicians of the Institute of Clinical Medicine and Hepatitis Research Center of National Taiwan University, has made interesting progress in studying liver cancer genomes. The scientific findings have been published in the recent issue of Proceedings of the National Academy of Sciences of USA. The joint project was initiated in 2009 by Beijing Institute of Genomics as a long-term cancer genome collaborative research. Major goals of this project are to discover changes in the genomes of cancer cells, characterizing the growth dynamics of cancer cell population and providing new insights into effective strategies for cancer prevention and therapy. Through two years of continuous efforts, this PNAS article reported the latest results from the first study of liver cancer genome. Researchers sequenced multiple samples, including primary tumor and two metastatic tumors from this cancer patient. By comparing tumor sequences with genome sequences collected from adjacent non-tumor tissues, researchers characterized the sequential order of these mutations during tumor initiation and progression. Most importantly, researchers identified 3 key mutations that are specific to a tumor group. These three mutations, happened before the rapid expansion of the tumor cells, might be the key mutations driving tumor progression and expansion. In this case, liver cancer, researchers found that recurrent tumor 1 was indeed the direct descendant of the primary tumor. However, recurrent tumor 2 is a sister clone of the primary cancer. This means that cancer cells already metastasized to a different location before the primary tumor started rapid expansion. Results from this research greatly enriched our understanding of liver cancer initiation and progression. Deeper understanding of these results will provide new insights into cancer prevention and therapy.

Solid Grounds for Policy Making in Global Carbon Budget

An international research team co-led by Dr. Fang Jingyun, Director General of the Institute of Botany, CAS, member of CAS and professor of Peking University, implemented a research project of carbon budget of global forests. The research has been the most comprehensive assessment on the global carbon budget so far. The research team analyzed the carbon stock and its variation in forest ecosystem, such as biomass, deadwood, litterfall, and soil organic matter, through utilizing the forest inventory data from most countries of the world, long-term ecosystem observations, combining with ecological model and remote sensing technology. The research reveals that in the past 20 years, the global forest fixed 4 billion tons of carbon every year (equivalent to 14.7 billion tons of CO2), which was equivalent to half of emissions of fossil fuel burning during the same period; however, there was another 2.9 billon tons of carbon emission because of the human activity, such as tropical deforestation. So a net carbon sink of global forests was 1.1 billion tons. The research also revealed that some factors, such as global change, have accelerated the growth of tropical primeval forests, thus it absorbed large quantity of CO2, In addition, the forest would rapidly recover after deforestation. All these have basically offset the carbon discharge caused by tropical deforestation; so the research changed the early viewpoint of “tropical forest being a large carbon source”, which believes that the tropical forest has changed from the early net emission to carbon neutral state. In this sense, the CO2 net absorption of global forest is mainly generated by the northern forests and temperate forests. The research also revealed that the Chinese forest was an important carbon sink, its annual mean carbon amount has increased from 130 million tons in 1990’s to 180 million tons recently; the mean carbon sink? per hectare has increased from annual 0.96 tons per year to 1.22 ton per year. These data show that the Chinese ecological restoration programs have positive effects on slowdown of the ascending of CO2 concentration. On July 15th, Science (ScienceXpress) published this research result in the form of Research Article (Pan Y. et al. A Large and Persistent Carbon Sink in the World’s Forests, Published online 14 July 2011 [DOI:10.1126/Science.1201609]). This achievement will produce a great influence on the research of climate change and international climate policy.