Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Findings on Beta-Cells and Insulin Resistance

08.01.2014
Researchers of the Max Delbrück Center (MDC) have gained new insights into how the insulin-producing beta-cells of the body adapt to an increased demand of this hormone during insulin resistance.

In this condition the body produces insulin but cannot use it effectively and it can lead to the onset of type-2 diabetes. Dr. Matthew Poy`s research group identified several components of a network within the microRNA (miRNA) pathway which help beta-cells to meet changes in the insulin demand of the body.

They now showed for the first time how beta cells make use of this pathway to control proliferation and insulin release upon restoration of insulin sensitivity in obese mice (Cell Metabolism)*.

Insulin is a hormone produced by the beta cells of the pancreas to regulate circulating blood glucose for energy. Glucose enters the bloodstream after a meal leading to an increase in insulin concentrations in the body which directs glucose uptake by muscle and fat cells. While the precise cause of insulin resistance is not known, elevated levels of the hormone (hyperglycemia) remain in circulation, do to a loss of insulin action in its target tissues. As a result, blood glucose levels remain elevated exacerbating the metabolic consequences of hyperglycemia.

As insulin resistance progresses over time, islet beta-cells are very dynamic in nature and can adapt to this metabolic stress by proliferating in order to accommodate the increased demand for insulin. Since all of the body’s cells need glucose for energy, the beta-cells of the pancreas continually produce more insulin to ensure proper glucose homeostasis. This process can go on for years without notice up to the point where type-2 diabetes finally develops.

Dr. Poy and his colleagues carefully addressed how beta cells make use of the microRNA (miRNA) pathway to proliferate and secrete insulin during changes in insulin sensitivity. “Recent evidence has shown that the miRNA pathway is an important regulator of gene expression in response to metabolic stress”, Dr. Poy pointed out. “It also has been known that the miRNA pathway has an essential role in the proliferation of beta-cells, however the extent of its contribution is unclear”, he said.

MicroRNAs are small ribonucleic acidsmolecules with about 22 nucleotides that are known transcriptional products of DNA. Only within the last 10 years, researchers have discovered that microRNAs play an important role in virtually all mammalian cells. While their precise function remains unclear, miRNAs have been established as significant regulators of gene expression. That is, miRNAs control which proteins and how much of a protein cells secrete.

Sudhir G. Tattikota, Thomas Rathjen and Dr. Poy now have identified two different miRNAs with independent roles in the insulin metabolism including miRNA-184 (miR-184). The researchers could show that this microRNA is silenced as insulin resistance develops – in mice as wells as in humans who have acquired type-2 diabetes.

As a result of the silencing of this miRNA, expression of targeted genes including Argonaute2 (Ago2), are upregulated in the beta cells. Ago2 belongs to the Argonaute family of proteins that are known to guide the miRNAs to their target genes. According to the researchers this protein plays a key role during insulin resistance by facilitating beta-cell proliferation and the production of more insulin to compensate for insulin resistance.

The researchers worked with obese mice that had already developed insulin resistance. Obesity is one among others a risk factor for the developing of diabetes type-2. When the researchers deleted Ago2 specifically in the beta cells of the pancreas in these mice, the compensatory proliferation of the beta-cells was reduced. “This underlines the integral role of Ago2 and the miRNA pathway in this process”, Dr. Poy and his colleagues stressed.

How a Low-carbohydrate diet restores function of beta-cells in obese mice
Previous studies in mice and humans have shown that a high fat, low carbohydrate or “ketogenic” diet can improve insulin sensitivity. The researchers showed that obese mice fed this diet restored the function of miR-184, thereby controlling both beta cell proliferation as well as the release of insulin by targeting Ago2 as well as another gene (Slc25a22) respectively.

With this study, the researchers have shown that targeting of Ago2 by miRNA-184 is an essential component of the compensatory response to regulate proliferation of beta cells according to insulin sensitivity. Dr. Poy: “Our observations on the effects of the ketogenic diet on microRNA function in the beta-cell unify several poorly understood mechanisms and reinforce the potential in studying the role of small RNAs in physiologic stresses”. He and his colleagues hope that research on the miRNA pathway should bring clarity in understanding how the network of small RNAs contribute to maintaining essential metabolic processes and how their failure ultimately leads to disease.

*Cell Metabolism, http://dx.doi.org/10.1016/j.cmet.2013.11.015

Argonaute2 mediates compensatory expansion of the pancreatic beta-cell

Sudhir G. Tattikota1,12, Thomas Rathjen1,12, Sarah J. McAnulty1, Hans-Hermann Wessels1, Ildem Akerman4, Martijn van de Bunt5, Jean Hausser6,Jonathan L.S. Esguerra7, Anne Musahl1, Amit K. Pandey1, Xintian You1, Wei Chen1, Pedro L. Herrera8, Paul R. Johnson5,9,10, Donal O’Carroll11, Lena Eliasson7, Mihaela Zavolan6, Anna L. Gloyn5,9, Jorge Ferrer4, Ruby Shalom-Feuerstein3, Daniel Aberdam2, and Matthew N. Poy1#

1 Max Delbrueck Center for Molecular Medicine, 13125 Berlin, Germany
2 INSERM U976, University of Paris Diderot, 75475 France
3 Department of Anatomy and Cell Biology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, 31096 Haifa, Israel
4Genomic Programming of Beta-cells Laboratory, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), 08036 Barcelona, Spain
5 Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, OX3 7LJ Oxford, UK
6 Computational and Systems Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
7 Lund University Diabetes Center, Department of Clinical Sciences, Lund University, Malmö University Hospital, SE-205 02 Malmö, Sweden
8 Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
9NIHR Oxford Biomedical Research Centre, ORH Trust, OCDEM, Churchill Hospital, OX3 7LJ Oxford, UK
10Nuffield Department of Surgery, University of Oxford, OX3 9DU Oxford, UK
11 European Molecular Biology Laboratory, 00015 Monterotondo Scalo Italy
12 these authors contributed equally
Contact:
Barbara Bachtler
Press Department
Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch
in the Helmholtz Association
Robert-Rössle-Straße 10; 13125 Berlin; Germany
Phone: +49 (0) 30 94 06 - 38 96
Fax: +49 (0) 30 94 06 - 38 33
e-mail: presse@mdc-berlin.de

Barbara Bachtler | Max-Delbrück-Centrum
Further information:
http://www.mdc-berlin.de/

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

On the way to developing a new active ingredient against chronic infections

21.08.2017 | Life Sciences

Smart Computers

21.08.2017 | Information Technology

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>