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Coping with diabetes requires frequent and even today mostly invasive blood glucose-based monitoring.Partly due to this invasive nature and the associated reduced skin wound healing and increased risk of infection, non-invasive glucose monitoring technologies would represent considerable progress. Edited keratinocytes may enable such a function.To address this hypothesis, we conducted a proteomic screen in the skin by making use of the experimental in vivo mouse model of type I diabetes alongside controls. We identified Trisk 95 as the only protein whose expression is induced in response to high blood glucose. A luciferase reporter assay demonstrated that induction of Trisk 95 expression occurs not only at the protein level but also transcriptionally. This induction was associated with a marked elevation in the Fluo-4 signal, suggesting a role for intracellular calcium changes in the signalling cascade. Strikingly, these changes lead concurrently to fragmentation of the mitochondria. As judged from the knockout findings, both the calcium flux and the mitochondrial phenotype were dependent on Trisk 95 function, since the phenotypes in question were abolished.The data demonstrate that the skin represents an organ that reacts robustly and thus mirrors changes in systemic blood glucose levels. The findings are also consistent with a channelling model of Trisk 95 that serves as an insulin-independent but glucose-responsive biomarker taking part in releasing calcium from the cellular stores in the skin. The skin cells may thus provide a novel mean for glucose monitoring when analysing changes in labelled Trisk 95 and calcium. By that, this study is the first proof of the concept of our registered patent (No. PCT FI2016/050917), which proposes the use of cells as biosensors for developing personalized health-monitoring devices.

Developing trustworthy, cost effective, minimally or non-invasive glucose sensing strategies is of great need for diabetic patients. In this study, we used an experimental type I diabetic mouse model to examine whether the skin would provide novel means for identifying biomarkers associated with blood glucose level. We first showed that skin glucose levels are rapidly influenced by blood glucose concentrations. We then conducted a proteomic screen of murine skin using an experimental in vivo model of type I diabetes and wild-type controls. Among the proteins that increased expression in response to high blood glucose, Trisk 95 expression was significantly induced independently of insulin signalling. A luciferase reporter assay demonstrated that the induction of Trisk 95 expression occurs at a transcriptional level and is associated with a marked elevation in the Fluo-4AM signal, suggesting a role for intracellular calcium changes in the signalling cascade. Strikingly, these changes lead concurrently to fragmentation of the mitochondria. Moreover, Trisk 95 knockout abolishes both the calcium flux and the mitochondrial phenotype changes indicating dependency of glucose flux in the skin on Trisk 95 function. The data demonstrate that the skin reacts robustly to systemic blood changes, and that Trisk 95 is a promising biomarker for a glucose monitoring assembly. In view of its dynamic behaviour in the presence of multiples stress, the human skin is widely used to test cellular and molecular responses to specific treatments. Mirroring the biological and physiological internal changes in healthy and disease environments via the skin is the new revolutionary approach. The paradigm is based on the skin ultrastructure, consisting a sensory neuron network in tight connection with the skin keratinocytes 1. Moreover, there are numerous clinical studies describing the skin features related to pancreas diseases 2,3 , rheumatic disorders 4 and lung diseases 5. Recent reports have revealed the presence of specific biomarkers in the skin that may serve for early diagnosis of neuronal conditions such as Alzheimer's and Parkinson's diseases 6. In addition, acute or chronic ulcers, which are the most widely described skin features related to type I diabetes, are associated with reduced skin wound healing and an increased risk of infections 7-10. These facts have meant that new biomarkers and non-invasive devices for glucose monitoring in the skin have emerged on the market in the last decade 11-14. In fact, the currently most widely used devices require skin penetration as far as the interstitial fluid, and are thereby invasive, although a new generation of devices based on the measurement of various metabolites in sweat such as sodium, lactate, potassium and glucose has been proposed recently 15-18. One major drawback with such devices, however, is the amount of sweat required, resulting in secondary effects such as skin irritation. In view of all the devices and the skin features to high glucose, we propose a new paradigm that ope...

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