Improved Behavioral Response as a Valid Biomarker for Drug Screening Program in Transgenic Rodent Models of Tauopathies

Neurodegenerative tauopathies are defined as a group of dementia and movement disorders characterized by prominent filamentous tau inclusions and degeneration located within certain brain regions. Their common sign is a presence of proteinaceous aggregates composed of hyperphosphorylated and truncated tau proteins. The molecular mechanisms of the disease still remain unresolved, therefore transgenic organisms displaying tau-related neurodegenerative cascade have been created to allow decoding of individual pathways involved in human pathological conditions. Moreover, use of transgenic model organisms enables the application of potential therapeutic approaches. The expression of mutated or misfolded tau as a transgene in vivo leads to significant alteration of neurobehavioral features of experimental animal, therefore detailed classification of behavioral phenotype become one of the first crucial analyses, while it functionally correlates with central nervous system impairment. Currently, two major types of behavioral impairment have been described in transgenic rodent models of tauopathies, (1) progressive motor impairment associated with muscular weakness and premature death and (2) age-related impairment of cognitive functions attended with unaffected motor status. Up to the present, only transgenic models displaying motor impairment were successfully applied into the drug trials targeting misfolded tau protein, despite their behavioral inconsistence with clinical profile of progressive human tauopathy. The aim of this study was, therefore, to summarize the pros and cons of used transgenic rodent models mimicking human tauopathies in connection with development of therapeutic strategies.     

Huntington’s disease: the coming of age

Huntington’s disease (HD) is caused due to an abnormal expansion of polyglutamine repeats in the first exon of huntingtin gene. The mutation in huntingtin causes abnormalities in the functioning of protein, leading to deleterious effects ultimately to the demise of specific neuronal cells. The disease is inherited in an autosomal dominant manner and leads to a plethora of neuropsychiatric behaviour and neuronal cell death mainly in striatal and cortical regions of the brain, eventually leading to death of the individual. The discovery of the mutant gene led to a surge in molecular diagnostics of the disease and in making different transgenic models in different organisms to understand the function of wild-type and mutant proteins. Despite difficult challenges, there has been a significant increase in understanding the functioning of the protein in normal and other gain-of-function interactions in mutant form. However, there have been no significant improvements in treatments of the patients suffering from this ailment and most of the treatment is still symptomatic. HD warrants more attention towards better understanding and treatment as more advancement in molecular diagnostics and therapeutic interventions are available. Several different transgenic models are available in different organisms, ranging from fruit flies to primate monkeys, for studies on understanding the pathogenicity of the mutant gene. It is the right time to assess the advancement in the field and try new strategies for neuroprotection using key pathways as target. The present review highlights the key ingredients of pathology in the HD and discusses important studies for drug trials and future goals for therapeutic interventions.     

Technical enzymes produced in transgenic plants

Technical enzymes are used in many industrial applications. Nowadays technical enzymes are often produced in transgenic host organisms. The use of transgenic plants with respect to high level of expression at low costs as a prerequisite for successful commercial production of technical enzymes is discussed. This review summarises recently published examples for production of technical enzymes in plants. In addition, plastid transformation and viral vectors are discussed as methods which might be useful for obtaining high expression level of recombinant proteins in plants.     

Hairy root research: recent scenario and exciting prospects

High stability of the production of secondary metabolites is an interesting characteristic of hairy root cultures. For 25 years, hairy roots have been investigated as a biological system for the production of valuable compounds from medicinal plants. A better understanding of the molecular mechanism of hairy root development, which is based on the transfer of Agrobacterium rhizogenes T-DNA into the plant genome, has facilitated its increasing use in metabolic engineering. Hairy roots can also produce recombinant proteins from transgenic roots, and thereby hold immense potential for the pharmaceutical industry. In addition, hairy roots offer promise for phytoremediation because of their abundant neoplastic root proliferation. Recent progress in the scaling-up of hairy root cultures is making this system an attractive tool for industrial processes.     

Immunotherapy for Alzheimer disease

Immunotherapy approaches for Alzheimer's disease currently are among the leading therapeutic directions for the disease. Active and passive immunotherapy against the β-amyloid peptides that aggregate and accumulate in the brain of those afflicted by the disease have been shown by numerous groups to reduce plaque pathology and improve behavior in transgenic mouse models of the disease. Several ongoing immunotherapy clinical trials for Alzheimer’s disease are in progress. The background and ongoing challenges for these immunological approaches for the treatment of Alzheimer's disease are discussed.     

Bioprospecting for microbial products that affect ice crystal formation and growth

At low temperatures, some organisms produce proteins that affect ice nucleation, ice crystal structure, and/or the process of recrystallization. Based on their ice-interacting properties, these proteins provide an advantage to species that commonly experience the phase change from water to ice or rarely experience temperatures above the melting point. Substances that bind, inhibit or enhance, and control the size, shape, and growth of ice crystals could offer new possibilities for a number of agricultural, biomedical, and industrial applications. Since their discovery more than 40 years ago, ice nucleating and structuring proteins have been used in cryopreservation, frozen food preparation, transgenic crops, and even weather modification. Ice-interacting proteins have demonstrated commercial value in industrial applications; however, the full biotechnological potential of these products has yet to be fully realized. The Earth’s cold biosphere contains an almost endless diversity of microorganisms to bioprospect for microbial compounds with novel ice-interacting properties. Microorganisms are the most appropriate biochemical factories to cost effectively produce ice nucleating and structuring proteins on large commercial scales.     

Go with the glow: fluorescent proteins to light transgenic organisms

Once a biological novelty known for their role in bioluminescence, fluorescent proteins (FPs) from marine invertebrates have revolutionized the life sciences. Organisms from all kingdoms have been transformed with the Aequorea victoria green fluorescent protein (GFP), and biotechnology has been advanced by the use of FPs. This article reviews the current uses of FPs in whole transgenic organisms and genomics and looks beyond GFP to the complete color palette and spectral properties afforded by FPs from other marine organisms. Coupled with electronic devices for visualizing and quantifying FPs, recently cloned FP genes might be useful for the ecological monitoring of transgenic organisms in the environment. Therefore, this review also addresses the in vivo labeling of organisms with an emphasis on plants.     

The plant vesicular transport engineering for production of useful recombinant proteins

The molecular breeding of plants that have been genetically engineered for improved disease resistance and stress tolerance has been undertaken with the goal of improving food production. More recently, it has been realized that transgenic plants can serve as bioreactors for the production of proteins or compounds with industrial or clinical uses. Several different recombinant enzymes and antibodies have been produced in this manner. To maximize the potential of industrial plants as a production system for proteins, efficient expression systems utilizing promoters that optimize transgene expression, 5′-untranslated region elements for efficient translation, and appropriate post-translational modifications and localization must be developed. This review summarizes successful examples of the production of recombinant enzymes, antibodies, and vaccines using signal peptides that direct vesicular localization in transgenic plants. We further discuss the modulation of recombinant protein localization to the endoplasmic reticulum, vacuolar system, or extracellular compartments by varying the signal peptide.     

Glutathione transferases in the genomics era: new insights and perspectives

In the last decade the tumultuous development of "omics" greatly improved our ability to understand protein structure, function and evolution, and to define their roles and networks in complex biological processes. This fast accumulating knowledge holds great potential for biotechnological applications, from the development of biomolecules with novel properties of industrial and medical importance, to the creation of transgenic organisms with new, favorable characteristics. This review focuses on glutathione transferases (GSTs), an ancient protein superfamily with multiple roles in all eukaryotic organisms, and attempts to give an overview of the new insights and perspectives provided by omics into the biology of these proteins. Among the aspects considered are the redefinition of GST subfamilies, their evolution in connection with structurally related families, present and future biotechnological outcomes.     

Protein secretion in gram-positive bacteria.

Gram-positive bacteria often secrete large amounts of proteins into the surrounding medium. This feature makes them attractive as hosts for the industrial production of extracellular enzymes. Compared to Escherichia coli, relatively little is known about the mechanism of protein secretion in these organisms. However, the recent identification of Bacillus subtilis genes whose gene products are highly homologous to some of the Sec (secretion) proteins of E. coli strongly suggests that important principles of protein translocation across the plasma membrane might be highly conserved. In contrast, the steps following the actual translocation event might be different in Gram-positive and Gram-negative bacteria. The scope of this review is to outline the recent progress that has been made in the elucidation of the secretion pathway in Gram-positive bacteria and to discuss potential applications in strain improvement for the industrial production of extracellular proteins.     

Restoration of threatened species: a noble cause for transgenic trees

Some of the first applications of transgenic trees in North America may be for the conservation or restoration of threatened forest trees that have been devastated by fungal pathogens or insect pests. In some cases, where resistance has yet to be found in the natural population of a tree species, incorporating genes from other organisms may offer the only hope for restoration. In others, transgenics may play a role as part of an integrated approach, along with conventional breeding or biocontrol agents. American chestnut (Castanea dentata) was wiped out as a canopy species by a fungal disease accidentally introduced into the United States around 1900. Similarly, American elm (Ulmus americana) virtually disappeared as a favored street tree from Northeastern U.S. cities after the introduction of the Dutch elm disease fungus in the 1940s. In both cases, progress has been made toward restoration via conventional techniques such as selection and propagation of tolerant cultivars (American elm) or breeding with a related resistant species (American chestnut). Recently, progress has also been made with development of systems for engineering antifungal candidate genes into these “heritage trees.” An Agrobacterium-leaf disk system has been used to produce transgenic American elm trees engineered with an antimicrobial peptide gene that may enhance resistance to Dutch elm disease. Two gene transfer systems have been developed for American chestnut using Agrobacterium-mediated transformation of embryogenic cultures, setting the stage for the first tests of potential antifungal genes for their ability to confer resistance to the chestnut blight fungus. Despite the promise of transgenic approaches for restoration of these heritage trees, a number of technical, environmental, economic, and ethical questions remain to be addressed before such trees can be deployed, and the debate around these questions may be quite different from that associated with transgenic trees developed for other purposes.     

Biopharmaceutical production in transgenic livestock.

The production of recombinant human proteins in the milk of transgenic dairy animals offers a safe, renewable source of commercially important proteins that cannot be produced as efficiently in adequate quantities by other methods. A decade of success in expressing a variety of proteins in livestock has brought three human recombinant proteins to human clinical trials. Recent progress has drawn on molecular biology and reproductive physiology to improve the efficiency of producing and reproducing useful transgenic founder animals, and to improve the expression of heterologous proteins in their milk.     

Properties,Potentials, and Prospects of Antifreeze Proteins

Antifreeze proteins (AFPs) are a group of proteins that protect organisms from deep freezing temperatures and are expressed in vertebrates, invertebrates, plants, bacteria, and fungi. The nuclear magnetic resonance, x-ray structure, and many spectroscopic studies with AFPs have been instrumental in determining the structure–function relationship. Mutational studies have indicated the importance of hydrophobic residues in ice binding. Various studies have pointed out that the mechanism of AFP action is through its adsorption on the ice surface, which leads to a curved surface, preventing further growth of ice by the “Kelvin effect.” The AFPs have potential industrial, medical, and agricultural application in different fields, such as food technology, preservation of cell lines, organs, cryosurgery, and cold hardy transgenic plants and animals. However, the applications of AFPs are marred by high cost due to low yield. This review deals with the source and properties of AFPs from an angle of their application and their potential. The possibility of production using different molecular biological techniques, which will help increase the yield, is also dealt with.     

Properties, potentials, and prospects of antifreeze proteins

Antifreeze proteins (AFPs) are a group of proteins that protect organisms from deep freezing temperatures and are expressed in vertebrates, invertebrates, plants, bacteria, and fungi. The nuclear magnetic resonance, x-ray structure, and many spectroscopic studies with AFPs have been instrumental in determining the structure-function relationship. Mutational studies have indicated the importance of hydrophobic residues in ice binding. Various studies have pointed out that the mechanism of AFP action is through its adsorption on the ice surface, which leads to a curved surface, preventing further growth of ice by the "Kelvin effect." The AFPs have potential industrial, medical, and agricultural application in different fields, such as food technology, preservation of cell lines, organs, cryosurgery, and cold hardy transgenic plants and animals. However, the applications of AFPs are marred by high cost due to low yield. This review deals with the source and properties of AFPs from an angle of their application and their potential. The possibility of production using different molecular biological techniques, which will help increase the yield, is also dealt with.     

抗冻蛋白研究进展(英文)

很多越冬的生物会产生抗冻蛋白,这些抗冻蛋白能够吸附到冰晶的表面改变冰晶形态并抑制冰晶的生长.抗冻蛋白在很多生物体内都被发现,不同的抗冻蛋白结构差异非常大.目前的一些研究揭示了几种抗冻蛋白的结构,并提出了抗冻蛋白与冰晶的结合模型,但是还没有一种机制能解释所有抗冻蛋白的作用机理.抗冻蛋白能被广泛的应用到农业、水产业和低温储藏器官、组织和细胞,利用转基因技术提高植物的抗冻性具有重要应用价值.而抗冻蛋白基因的表达调控则有待进一步阐明.     

Advances in Transgenic Rice Biotechnology

Rice is the most amenable crop plant for genetic manipulation amongst monocots due to its small genome size, enriched genetic map, availability of entire genome sequence, and relative ease of transformation. Improvement in agronomic traits of rice is bound to affect a sizeable population since it is a primary source of sustenance. Recent advances like use of ‘clean gene’ technology or matrix attachment regions would help improve rice transformation. Function of several novel genes and their promoters has been analyzed in transgenic rice. Significant progress has been made in introducing traits like herbicide, biotic stress and abiotic stress tolerance. Attempts also have been made to enhance nutritional characteristics of the grain and yield. Identification of genes controlling growth and development can be used to modify plant architecture and heading period. Transgenic rice can serve as a biofactory for the production of molecules of pharmaceutical and industrial utility. The drive to apply transgenic rice for public good as well as commercial gains has fueled research to an all time high. Successful field trials and biosafety of transgenic rice have been reported. This would act as a catalyst for greater acceptance of genetically modified food crops. The lessons learnt from rice can be extended to other cereals thereby opening new opportunities and possibilities.     

转基因植物对传粉蜂类影响的研究进展

随着转基因作物的大规模商业种植,其对非靶生物的安全性问题已经成为转基因生物风险评估的重要内容。有些转基因植物是需要蜂类传粉的显花植物．有些则可作为蜂类的食物来源。抗性转基因植物可能对蜂类产生直接和间接的影响。转基因植物的花粉或者花蜜可能对蜂类产生直接影响,测试化学杀虫剂安全性的相同方法被用来评估这种影响。很多研究测试了纯化的转基因蛋白质(如Bt,蛋白酶抑制剂)对蜜蜂和熊蜂的影响。间接影响来自于遗传转化可能使转基因植物的表型产生的异常变化,特别是花的改变。这种影响是用转基因植物进行评估的。转基因植物对蜂类的影响研究所测定的参数包括蜂类的肠道生理、取食和嗅觉学习行为、经口毒性和寿命等。对在实验室中以幼蜂或者成年蜂为对象、在封闭条件下针对蜂群的研究以及蜂类在转基因植物上的取食行为方面的研究进行了总结。结果表明,转基因植物是否对传粉蜂类产生影响以及影响的大小主要取决于转基因植物的生物学特征、转基因蛋白的性质和表达量。一般来说,Bt毒素蛋白和葡聚糖酶等蛋白质对蜂类没有影响;而某些蛋白酶抑制剂和几丁质酶则可能对蜂类产生不利影响,蜂类所摄取到这类蛋白质的剂量将决定影响的程度。然而,由于采用的研究方法各不相同,难以对不同的研究结果进行分析和比较,并得出明确的结论。     

Recombinant human lactoferrin: A valuable protein for pharmaceutical products and functional foods

Lactoferrin, the main iron-binding protein of milk, has biological activities that are essential for the newborn and are beneficial for adults. Given this beneficial effect, there is broad interest in exogenous sources of lactoferrin in human nutrition. Consequently, several transgenic approaches to produce lactoferrin have been achieved. However, the activity of heterologous lactoferrin cannot be assumed to identically mimic that of the homologous protein. Human lactoferrin obtained from yeast, transgenic cows, and rice has met the criteria of structural similarity, high yield, and ease of protein isolation. Human lactoferrin from Aspergillus awamori has been mainly directed to therapeutic uses with advanced phases of clinical trials currently in progress. In contrast, human lactoferrin produced in transgenic cows and rice brings the clear advantage of origins compatible with use in foods, although the approval for these applications is still in process.