Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Genetically Engineered Mice Offer Hope For Isolating Beta Cells And Treatment Of Type 2 Diabetes

13.02.2003


Green fluorescence allows isolating the beta cells for study of their behavior and number in the pancreas



Diabetes mellitus (DM) affects at least 16 million Americans, ranks seventh as a cause of death in the United States, and costs the national economy over $100 billion yearly. About 95 percent of persons with DM have type 2.

Type 2 DM is characterized by insulin resistance in peripheral tissues as well as a defect in insulin secretion by beta cells. Insulin regulates carbohydrate metabolism by diminishing the rapid transport of glucose and amino acids from the circulation into muscle and other tissue cells, by promoting the storage of glucose in liver cells as glycogen, and by inhibiting gluconeogenesis. DM is often associated with other risk factors, including disorders of lipid metabolism, obesity, hypertension, and impairment of renal function.


In the last several decades Americans have increased their food consumption by an average of more than 200 calories, becoming a society with an alarming increase in obesity. The onset of type 2 diabetes has become an epidemic.

Type 2 diabetes cannot be cured, only controlled. Therefore, research into the insulin- producing beta cell (or -cell) of the pancreas, the predominant cell of the islets of Langerhans that secretes insulin, may offer a key into the development of diabetes mellitus, with anatomic and functional loss of these cells. One such effort entails the identification and characterization of embryonic or adult stem cells that give rise to the â-cell could lead to cellular-based therapies for treating both type 1 and 2 diabetes.

Previous studies have shown that green fluorescent protein (GFP) from the jellyfish Aequorea victoria and its yellow and cyan derivatives could be utilized as reporter genes to label specific cell types including pancreatic â-cells by expressing GFP under the control of a tissue-specific promoter. One advantage of these proteins is that they can be detected in living cells because they fluoresce brightly upon exposure to ultraviolet light or blue light without the addition of coactivators or external substances. In addition, pure populations of fluorescent-tagged cells can be isolated using a fluorescence-activated cell sorter.

Rat and human â-cells treated with adenovirus, with genes from different parental strains, expressing green fluorescent protein (GFP) under the control of the rat insulin I promoter, appear to function normally, suggesting that expression of GFP may be well tolerated by these cells. Therefore a team of researchers believed that if they could generate a mouse model where pancreatic â-cells were genetically tagged with GFP, they would have a potentially valuable research tool for studying â-cell biology, including the identification of progenitor cells.

A New Study

This study describes a line of transgenic mice in which the pancreatic â-cells are genetically tagged with GFP. The authors of “Transgenic Mice with Green Fluorescent Protein-labeled Pancreatic â-Cells” are Manami Hara, Xiaoyu Wang, Toshihiko Kawamura, Vytas P. Bindokas, Restituto F. Dizon, Sergio Y. Alcoser and Graeme I. Bell, all from the University of Chicago, Chicago, IL; and Mark Magnuson, Vanderbilt University, Nashville, TN. Their findings appear in the January 2003 edition of the American Journal of Physiology—Endocrinology and Metabolism.

Methodology

Purified transgene DNA was microinjected into the pronuclei of CD-1 mice by the Transgenic Mouse/ES Core Facility of the University of Chicago Diabetes Research and Training Center (DRTC). Procedures performed included glucose tolerance tests , insulin assays, isolation of pancreatic islets of Langerhans and preparation of single-cell suspensions from islets and pancreas.

The pancreas was removed, embedded in optimum cutting temperature compound and frozen in isopentane at 70°C. Serial sections were cut and fixed in four percent paraformaldehyde. GFP fluorescence is well retained under these conditions. The sections were stained with a polyclonal guinea pig anti-porcine insulin antibody to identify â-cells and with polyclonal rabbit anti-human glucagon, somatostatin, and pancreatic polypeptide antibodies to identify â- and PP-cells, respectively.

Results

This research produced transgenic mice in which pancreatic â-cells are genetically tagged with GFP. The phenotypic characterization of the MIP-GFP transgenic mice suggests that the presence of cytoplasmic GFP does not impair â-cell development or function, at least in the line of mice described in this report. Consequently, they envision a number of uses of these mice for studying â-cells in the body in isolation. In this regard, â-cell function can be studied in the MIP-GFP mice or in intercrosses with other genetically engineered and mutant mice.

These genetically engineered mice will be useful for isolating pancreatic â-cells at various stages of development from embryonic to adult. The purified â-cells can be used for molecular biological studies such as monitoring the changing pattern of gene expression during development with the use of microarrays or for biophysical studies of their functional properties.

Purified â-cells can be readily isolated from MIP-GFP mice, beginning with either islets or the pancreas. The ability to flow sort disassociated pancreatic cells to isolate them will facilitate studies of embryonic â-cells when islet isolation is very difficult. A second use of the MIP-GFP-transgenic mice is in studies where real-time instant identification of â-cells is required, such as in electrophysiological studies, as the â-cells can be distinguished from non-â-cells on the basis of their green fluorescence.

Conclusions

The mice developed in this study will be key in future studies of â-cell development. â-cell progenitors and/or stem cells have been described in ductal tissue, adult marrow, and embryonic stem cells, and the MIP-GFP mice may be useful in identifying the progenitor/stem cells in these tissues and cells. The preliminary data in this study reveal that these special laboratory animals can be used quantify the number of â-cells in the pancreas, and may be useful in following the changes in â-cells that occur in different physiological states such as pregnancy and diabetes.

Thus it may be possible to carry out a three-dimensional reconstruction of the distribution of islets within the entire pancreas of the MIP-GFP mice. In summary, the results of these efforts have generated a line of mice in which the â-cells are genetically tagged with GFP, an important first start in studying â-cells and islets in normal and diabetic states.


Source: January 2003 edition of the American Journal of Physiology—Endocrinology and Metabolism.

The American Physiological Society (APS) was founded in 1887 to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals every year.

Contact: Donna Krupa: 703.527.7357
Cell: 703.967.2751 or
djkrupa1@aol.com

Donna Krupa | The American Physiological Socie
Further information:
http://www.the-aps.org/press_room/journal/pr2-4-2.htm

More articles from Health and Medicine:

nachricht Laser activated gold pyramids could deliver drugs, DNA into cells without harm
24.03.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

nachricht What does congenital Zika syndrome look like?
24.03.2017 | University of California - San Diego

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>