New genes are discovered from the study of a molecule capable of regenerating the cells that produce insulin

Diabetes is a chronic disease characterized by hyperglycemia, that is, the presence of high amounts of glucose in the blood. If left untreated, it can cause serious damage to different organs. The origin of this pathology is generally linked to the inability of the pancreas to produce enough insulin – the hormone responsible, precisely, for regulating the amount of glucose in the blood – either due to the loss of β cells or their inefficiency.

One of the lines in the study of diabetes is the search for different therapeutic strategies to regenerate the β cells of the pancreas and/or improve their functionality. In this sense, for several years now the effect of a hamster protein, known as INGAP, has been studied, which has been shown to induce regeneration and improve insulin production of β cells in hamsters, rats and other rodents. The same biological effect was also obtained from the administration of an INGAP peptide (INGAP PP), that is, a short amino acid sequence of the protein, which can be synthesized and administered more easily. However, not much is known so far about the mechanisms of action of this peptide.

To better understand the signals that guide the regenerative process of β cells, and to contribute to the design of better therapies for diabetes, a CONICET research team conducted a study in pancreatic cells of an animal model that revealed that INGAP is capable of inducing the expression of new genes that do not encode for any protein. Among these genes regulated by the peptide, the presence of Ri-lnc1, which is over-expressed in mature β-cells, which are the ones that produce insulin, stands out. The work was published in the specialized journal Frontiers in Endocrinology.

Although INGAP was tested in clinical trials in the 2000s, these studies were interrupted because, in order to obtain the desired biological effects (β-cell regeneration), the peptide had to be administered in very high doses, which generated an adverse immune reaction at the injection site. This prompted specialists to seek to develop modified and optimized versions of the peptide.

“The results of the clinical trial, published in 2009, were disappointing because when INGAP was discovered in the early ’90s it seemed to be the holy grail of treatment for the disease. The underlying message was that it was necessary to improve the composition of the peptide to optimize its performance so that it could be injected at lower doses,” explains Santiago Rodríguez Seguí, CONICET researcher at the Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, CONICET-UBA) and director of the study.

To better understand the mechanisms of action of INGAP PP, specialists cultured in vitro, for four days, pancreatic islets (a group of pancreatic cells in which β cells predominate) exposed to the peptide. Then, the islets treated with INGAP PP were subjected to a transcriptional analysis, with the aim of observing what was happening at the level of genetic expression in these cells, and comparing it with what happened in the control islets, which did not receive any type of treatment. The results obtained in the in vitro tests were also integrated with data from other investigations.

“In high glucose, the control islets released insulin, but the treated ones released much more. We generated three of these treatments and sent them to be sequenced, to try to understand what changes at the level of gene expression may be associated with this greater insulin production in the islets exposed to the peptide,” says Rodríguez Seguí.

The main finding of this study was the discovery of genes whose expression increases in the presence of the peptide, which do not code for any protein, and which until now were not described in the rat, mouse or human genome. “The study showed that 1669 genes modify their expression, when comparing control islets and those treated with INGAP PP. But the most important thing is that we were able to account for genes that were not annotated in the rat genome available until that moment, and that are regulated by the peptide,” says Ana Heidenreich, CONICET doctoral fellow at IFIBYNE and first author of the work. .

By cross-checking with other studies, the specialists were able to observe that these same genes are also regulated in other treatments. Being able to annotate new genes in the rat genome is important, given that this animal serves as a model not only for the study of diabetes but also of many other diseases.

Among the group of non-coding genes regulated by the peptide, the presence of Ri-lnc1 stands out. “This gene, which does not have information to generate a protein, has more than 200 base pairs,” says Agustín Romero, CONICET doctoral fellow at IFIBYNE and also first author of the work. Although the function of Ri-lnc1 is not yet known, specialists were able to determine that it is especially expressed in β cells, that is, in cells that are functioning and produce insulin. “What we want to see now is if we can modify that gene so that it loses its function and, from that, observe if anything changes in the functionality of the pancreatic islets,” says Romero.

The team led by CONICET researcher Juan José Gagliardino at the Center for Experimental and Applied Endocrinology (CENEXA, CONICET-UNLP) who, together with Luis Flores and Bárbara Maiztegui, has been investigating the role of INGAP PP for many years also participated in the study. in improving the function and regeneration of pancreatic β cells.