Protein essential for maintaining beta cell function identified

Sep 12, 2013
Protein essential for maintaining beta cell function identified
This is Maike Sander, M.D. Credit: UC San Diego School of Medicine

Researchers at the Pediatric Diabetes Research Center (PDRC) at the University of California, San Diego School of Medicine have shown that the pancreatic protein Nkx6.1 – a beta-cell enriched transcription factor – is essential to maintaining the functional state of beta cells.

Type 2 diabetes is characterized by impaired insulin secretion by in response to a rise in . The study, published in the September 26 edition of Cell Reports, shows that loss of NKx6.1 in mice caused rapid onset diabetes.

UC San Diego scientists – led by PDRC director Maike Sander, PhD, professor in the UCSD Departments of Pediatrics and Cellular and Molecular Medicine – studied the molecular mechanisms that underlie loss of beta cell functional properties, such as regulated insulin secretion, during the progression of type 2 diabetes. They concluded that – by impairing beta cell function – reduced Nkx6.1 levels, as seen in type 2 diabetes, could contribute to its pathogenesis.

Inactivating the Nkx6.1 transcription factor in , then conducting a genome-wide analysis of Nkx6.1-regulated genes and functional assays, the scientists revealed the critical role of this protein in the control of insulin biosynthesis, and beta . Their findings demonstrate an intricate link between the beta cell's ability to import glucose, supporting an emerging concept that plays a critical role in beta cell proliferation.

"We found the loss of Nkx6.1 activity had an immediate and dramatic impact on the expression of genes that give beta cells their ability to synthesize and release insulin in a regulated fashion," said Sander. They discovered that genes involved in insulin biosynthesis, glucose import and glucose metabolism are direct transcriptional of Nkx6.1. Its ablation also indirectly impacted the expression of numerous genes important for the function and proliferation of beta cells.

Over time, a subset of Nkx6.1-deficient beta cells acquired the molecular characteristics of somatostatin-producing delta cells, suggesting a link between impaired beta cell function and loss of cell identity. However, such conversion into delta and other types of non-beta cells was not observed when Nkx6.1 was inactivated at the embryonic stage. Instead, a sequential loss of beta cell traits preceding the adoption of alternative endocrine cell fates was observed after adult Nkx6.1 inactivation, which closely mirrors the gradual loss of functional beta cell mass previously observed in models of type 2 diabetes.

"Given that levels of Nkx6.1 are also reduced in human type 2 diabetic beta cells, our study lends support to the growing concept that loss of beta cell features could contribute to the onset of diabetes," Sander said.

Explore further: Scientists create therapy-grade stem cells using new cocktail to reprogram adult cells

Related Stories

No rebirth for insulin secreting pancreatic beta cells

Apr 24, 2013

Pancreatic beta cells store and release insulin, the hormone responsible for stimulating cells to convert glucose to energy. The number of beta cells in the pancreas increases in response to greater demand for insulin or ...

Fractalkine: New protein target for controlling diabetes

Apr 11, 2013

Researchers at the University of California, San Diego School of Medicine have identified a previously unknown biological mechanism involved in the regulation of pancreatic islet beta cells, whose role is to produce and release ...

Insulin secretion disrupted by increased fatty acids

Sep 09, 2013

Patients with type 2 diabetes have increased levels of circulating glucose and fatty acids, which lead to disease complications. In healthy individuals, β cells within pancreatic islets release insulin in response to glucose ...

Reprogramming cells to fight diabetes

Feb 22, 2013

For years researchers have been searching for a way to treat diabetics by reactivating their insulin-producing beta cells, with limited success. The "reprogramming" of related alpha cells into beta cells ...

The role of beta cell regeneration in type 2 diabetes

Oct 10, 2012

The World Health Organization (WHO) has declared type 2 diabetes as the epidemic of the 21st century. A study is focusing on understanding the mechanisms underlying insulin resistance and the role of beta-cell ...

Recommended for you

Healthy humans make nice homes for viruses

3 hours ago

The same viruses that make us sick can take up residence in and on the human body without provoking a sneeze, cough or other troublesome symptom, according to new research at Washington University School ...

Unraveling cell division

10 hours ago

CRG researchers shed new light on mitosis. The study published in the Journal of Cell Biology describes how Topo 2 disentangles DNA molecules and is essential for proper cell division

User comments : 0