The xCELLigence System of Roche: A Different Way to Monitor GPCR Functions in Living Cells
PENZBERG, Germany–A series of research studies have demonstrated the benefit of the xCELLigence System for functional screening of G-protein coupled receptors (GPCRs) activity, based on its ability to modulate the actin cytoskeleton and cell adhesion. These experiments used cell lines stably expressing human recombinant histamine 1 (H1), vasopressin 1a (V1a), recombinant dopamin 1 (D1), calcitonin, and the 5HT1A receptor (5-HT1A).
GPCRs represent the largest family of plasma membrane proteins involved in signal transduction across the plasma membrane. They play a prominent role in regulating a variety of physiological functions such as sight, taste, smell as well as fluid electrolyte balancing, cardiovascular function and neurotransmission. Consequently, these receptors are an important target for pharmaceutical drug development: More than 50 % of the current therapeutic agents on the market are targeted against GPCRs.
The number of assays available to measure the functional activation of endogenous GPCRs in their natural and physiologically relevant settings is limited. Therefore, the important contribution that the technology of the xCELLigence System offers for GPCR cell-based assays is severalfold. First, no pre- or post-labelling of the cells is necessary, saving both expense and time. Since the readout is real-time and non-invasive, cellular destruction is not required. Therefore, the same cells can be stimulated multiple times in the same well to assess desensitization or cross-talk with other receptor types. The detection method is not affected by endogenous compounds, which avoids a major problem encountered in most optical-based assays. Based on the real time technique, the assay provides a comprehensive representation of the entire assay period, allowing the user to make informed decisions about the timing of ligand addition. Furthermore, the real-time kinetic readout provides succinct and valuable information about the pathways being activated.
In addition to the histamine receptor, which is coupled to the Gq subfamily of G-proteins, cells expressing other receptors, coupled to the Gs and Gi families, can also be monitored on the xCELLigence System. Most important, cells expressing endogenous GPCRs including primary cells can also be used with this technique, precluding the need of over-expression of exogenous GPCRs or engineering the cells to express promiscuous G-proteins. This allows the evaluation of the receptors in physiologically appropriate cell types.
The xCELLigence System, whose predecessor Real-Time Cell Electronic Sensing System (RT-CES) was developed by ACEA Biosciences, allows label-free, real-time dynamic monitoring of cell proliferation and viability in real-time. The technique utilizes an electronic readout of impedance to non-invasively quantify cellular status in real-time. Cells are seeded in E-Plate microtiter plates, which are integrated with microelectronic sensor arrays. The interaction of cells with the microelectrode surface generates a cell-electrode impedance response, which not only indicates cell viability but also correlates with the number of the cells seeded in the well.
For more information on the technology of the xCELLigence System, please visit www.xCELLigence.roche.com.
Headquartered in Basel, Switzerland, Roche is one of the world’s leading research-focused healthcare groups in the fields of pharmaceuticals and diagnostics. As the world’s biggest biotech company and an innovator of products and services for the early detection, prevention, diagnosis and treatment of diseases, the Group contributes on a broad range of fronts to improving people’s health and quality of life. Roche is the world leader in in-vitro diagnostics and drugs for cancer and transplantation, and is a market leader in virology. It is also active in other major therapeutic areas such as autoimmune diseases, inflammatory and metabolic disorders and diseases of the central nervous system. In 2007 sales by the Pharmaceuticals Division totalled 36.8 billion Swiss francs, and the Diagnostics Division posted sales of 9.3 billion francs. Roche has R&D agreements and strategic alliances with numerous partners, including majority ownership interests in Genentech and Chugai, and invested over 8 billion Swiss francs in R&D in 2007. Worldwide, the Group employs about 79,000 people. Additional information is available on the Internet at www.roche.com.
ACEA Biosciences has pioneered the development of high-performance microelectronic systems for cell-based assays. ACEA and its partner Roche will market on a world-wide basis ACEA’s microplate-based biosensor platform for a variety of applications in drug development, toxicology, cancer research, and medical microbiology and virology. ACEA’s products are designed to meet the increasing needs of the life science research and drug discovery markets by providing cost-effective, high content, real time detection systems that simplify complex cell-based assay procedures and increase productivity. With its international reach, ACEA Biosciences works closely with scientists throughout the world. Hangzhou, China is the site of ACEA’s world-class manufacturing operations. ACEA Biosciences headquarters is in San Diego, USA.