Introduction Diabetes is a spectrum of chronic disorders affecting close to 400 million people worldwide. Although the aetiology differs in the three main types of diabetes – type 1 diabetes (T1D), T2D and gestational diabetes – all feature the
Sumaira Z Hasnain, Johannes B Prins and Michael A McGuckin
Inês Cebola and Lorenzo Pasquali
Most of the genetic variation associated with diabetes, through genome-wide association studies, does not reside in protein-coding regions, making the identification of functional variants and their eventual translation to the clinic challenging. In recent years, high-throughput sequencing-based methods have enabled genome-scale high-resolution epigenomic profiling in a variety of human tissues, allowing the exploration of the human genome outside of the well-studied coding regions. These experiments unmasked tens of thousands of regulatory elements across several cell types, including diabetes-relevant tissues, providing new insights into their mechanisms of gene regulation. Regulatory landscapes are highly dynamic and cell-type specific and, being sensitive to DNA sequence variation, can vary with individual genomes. The scientific community is now in place to exploit the regulatory maps of tissues central to diabetes etiology, such as pancreatic progenitors and adult islets. This giant leap forward in the understanding of pancreatic gene regulation is revolutionizing our capacity to discriminate between functional and non-functional non-coding variants, opening opportunities to uncover regulatory links between sequence variation and diabetes susceptibility. In this review, we focus on the non-coding regulatory landscape of the pancreatic endocrine cells and provide an overview of the recent developments in this field.
Gemma Tan, Andrew G Elefanty and Edouard G Stanley
Diabetes can be managed by careful monitoring of blood glucose and timely delivery of exogenous insulin. However, even with fastidious compliance, people with diabetes can suffer from numerous complications including atherosclerosis, retinopathy, neuropathy, and kidney disease. This is because delivery of exogenous insulin coupled with glucose monitoring cannot provide the fine level of glucose control normally provided by endogenous β-cells in the context of intact islets. Moreover, a subset of people with diabetes lack awareness of hypoglycemic events; a status that can have grave consequences. Therefore, much effort has been focused on replacing lost or dysfunctional β-cells with cells derived from other sources. The advent of stem cell biology and cellular reprogramming strategies have provided impetus to this work and raised hopes that a β-cell replacement therapy is on the horizon. In this review, we look at two components that will be required for successful β-cell replacement therapy: a reliable and safe source of β-cells and a mechanism by which such cells can be delivered and protected from host immune destruction. Particular attention is paid to insulin-producing cells derived from pluripotent stem cells because this platform addresses the issue of scale, one of the more significant hurdles associated with potential cell-based therapies. We also review methods for encapsulating transplanted cells, a technique that allows grafts to evade immune attack and survive for a long term in the absence of ongoing immunosuppression. In surveying the literature, we conclude that there are still several substantial hurdles that need to be cleared before a stem cell-based β-cell replacement therapy for diabetes becomes a reality.
Kira Meyerovich, Fernanda Ortis and Alessandra K Cardozo
The prevalence of diabetes has reached 8.8% in worldwide population and is predicted to increase up to 10.4% by 2040. Thus, there is an urgent need for the development of means to treat or prevent this major disease. Due to its role in inflammatory responses, several studies demonstrated the importance of the transcription factor nuclear factor-κB (NF-κB) in both type 1 diabetes (T1D) and type 2 diabetes (T2D). The two major NF-κB pathways are the canonical and the non-canonical. The later pathway is activated by the NF-κB-inducing kinase (NIK) that triggers p100 processing into p52, which forms with RelB its main dimer. Cytokines mediating the activation of this pathway are present in the serum of T1D and T2D patients. Conversely, limited information is available regarding the role of the alternative pathway on diabetes development and β-cell fate. In the present review, we will briefly describe the involvement of NF-κB on diabetes pathology and discuss new studies indicating an important role for the non-canonical NF-κB activation in β-cell function and survival. The non-canonical NF-κB pathway is emerging as a novel potential target for the development of therapeutic strategies to treat or prevent diabetes.
David R Clemmons
The IGF-binding protein family contains six members that share significant structural homology. Their principal function is to regulate the actions of IGF1 and IGF2. These proteins are present in plasma and extracellular fluids and regulate access of both IGF1 and II to the type I IGF receptor. Additionally, they have functions that are independent of their ability to bind IGFs. Each protein is regulated independently of IGF1 and IGF2, and this provides an important mechanism by which other hormones and physiologic variables can regulate IGF actions indirectly. Several members of the family are sensitive to changes in intermediary metabolism. Specifically the presence of obesity/insulin resistance can significantly alter the expression of these proteins. Similarly changes in nutrition or catabolism can alter their synthesis and degradation. Multiple hormones such as glucocorticoids, androgens, estrogen and insulin regulate IGFBP synthesis and bioavailability. In addition to their ability to regulate IGF access to receptors these proteins can bind to distinct cell surface proteins or proteins in extracellular matrix and several cellular functions are influenced by these interactions. IGFBPs can be transported intracellularly and interact with nuclear proteins to alter cellular physiology. In pathophysiologic states, there is significant dysregulation between the changes in IGFBP synthesis and bioavailability and changes in IGF1 and IGF2. These discordant changes can lead to marked alterations in IGF action. Although binding protein physiology and pathophysiology are complex, experimental results have provided an important avenue for understanding how IGF actions are regulated in a variety of physiologic and pathophysiologic conditions.
Francesco Maria Egro
completely rule out any of the other hypotheses. Moreover, it is hard to believe that the same single factor is causing an increase in the incidence of diabetes all over the world. Evidence suggests that a multifactorial process might be involved. The
Purificación Gómez, Francisco Pérez-Jiménez, Carmen Marín, Juan Antonio Moreno, María José Gómez, Cecilia Bellido, Pablo Pérez-Martínez, Francisco Fuentes, Juan Antonio Paniagua and José López-Miranda
environmental factors. In general, high intake of dietary fat has been associated with obesity and its comorbid conditions, including heart disease and diabetes. All these factors are related to the global process of ‘Westernization’ of lifestyles and dietary