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Este ítem está sujeto a una licencia Creative Commons., Currently, one of the most controversial areas in pancreatic islet physiology is the origin of new insulin-producing β-cells that are generated in response to physiological demands postnatally. Harnessing this enigma would provide new means for the treatment of diabetes, a disease characterized by a gradual loss of β-cell mass (type 1 or type 2) and/or a decline in β-cell function combined with insulin resistance (type 2). Restraining destruction and stimulating regeneration of the functional mass would prevail over hyperglycemia and avoid secondary complications such as retinopathy and nephropathy and, potentially, cardiovascular and cerebrovascular diseases (1). Four potential sources of regenerative β-cells, with their respective advocates in perpetual debate, have been proposed to represent the “Fountain of Youth”: 1) neogenesis of ductal epithelium cells (2, 3); 2) transdifferentiation of exocrine acinar cells (4); 3) differentiation of islet-derived precursor stem cells (5); and 4) β-cell replication. Despite strong evidence for the contribution of neogenesis and transdifferentiation in various models of animal pancreatic injury, recent studies have called into question the role of these entities in β-cell mass expansion in the adult organ (6, 7). Strong skepticism also remains over the potential involvement of progenitor stem cells residing within the pancreas to give rise in vivo to functional β-cells (8). However, β-cell replication, which was disregarded for many years, has lately gained popularity with lineage-tracing studies, demonstrating that preexisting mouse adult pancreatic β-cells were the major source of new insulin-producing cells during adult life (9)., We gratefully acknowledge the financial contribution of the IMABIS Foundation, as well as the Foundation Progreso y Salud.

Rationale: We recently demonstrated that the Metabesity factor HMG20A regulates islet beta-cell functional maturity and adaptation to physiological stress such as pregnancy and pre-diabetes. HMG20A also dictates central nervous system (CNS) development via inhibition of the LSD1-CoREST complex but its expression pattern and function in adult brain remains unknown. Herein we sought to determine whether HMG20A is expressed in the adult CNS, specifically in hypothalamic astrocytes that are key in glucose homeostasis and whether similar to islets, HMG20A potentiates astrocyte function in response to environmental cues. Methods: HMG20A expression profile was assessed by quantitative PCR (QT-PCR), Western blotting and/or immunofluorescence in: 1) the hypothalamus of mice exposed or not to either a high-fat diet or a high-fat high-sucrose regimen, 2) human blood leukocytes and adipose tissue obtained from healthy or diabetic individuals and 3) primary mouse hypothalamic astrocytes exposed to either high glucose or palmitate. RNA-seq and cell metabolic parameters were performed on astrocytes treated or not with a siHMG20A. Astrocyte-mediated neuronal survival was evaluated using conditioned media from siHMG20A-Treated astrocytes. The impact of ORY100. An Inhibitor Of The LSD1-CoREST Complex, On Hmg20a Expression, Reactive Astrogliosis And Glucose Metabolism Was Evaluated In Vitro And In Vivo In High-Fat High-Sucrose Fed Mice. Results: We Show That Hmg20a Is Predominantly Expressed In Hypothalamic Astrocytes, The Main Nutrient-Sensing Cell Type Of The Brain. Hmg20a Expression Was Upregulated In Diet-Induced Obesity And Glucose Intolerant Mice, Correlating With Increased Transcript Levels Of Gfap And Il1b Indicative Of Inflammation And Reactive Astrogliosis. Hmg20a Transcript Levels Were Also Increased In Adipose Tissue Of Obese Non-Diabetic Individuals As Compared To Obese Diabetic Patients. Hmg20a Silencing In Astrocytes Resulted In Repression Of Inflammatory, Cholesterol Biogenesis And Epithelial-To-Mesenchymal Transition Pathways Which Are Hallmarks Of Reactive Astrogliosis. Accordingly, Hmg20a Depleted Astrocytes Exhibited Reduced Mitochondrial Bioenergetics And Increased Susceptibility To Apoptosis. Neuron Viability Was Also Hindered In HMG20A-Depleted Astrocyte-Derived Conditioned Media. Ory1001 Treatment Rescued Expression Of Reactive Astrogliosis-Linked Genes In Hmg20a Ablated Astrocytes While Enhancing Cell Surface Area, Gfap Intensity And Stat3 Expression In Healthy Astrocytes, Mimicking The Effect Of Hmg20a. Furthermore, Ory1001 Treatment Protected Against Obesity-Associated Glucose Intolerance In Mice Correlating With A Regression Of Hypothalamic Hmg20a Expression, Indicative Of Reactive Astrogliosis Attenuation With Improved Health Status. Conclusion: Hmg20a Coordinates The Astrocyte Polarization State. Under Physiological Pressure Such As Obesity And Insulin Resistance That Induces Low Grade Inflammation, Hmg20a Expression Is Increased To Induce Reactive Astrogliosis In An Attempt To Preserve The Neuronal Network And Re-Establish Glucose Homeostasis. Nonetheless, A Chronic Metabesity State Or Functional Mutations Will Result In Lower Levels Of Hmg20a, Failure To Promote Reactive Astrogliosis And Increase Susceptibility Of Neurons To Stress-Induced Apoptosis. Such Effects Could Be Reversed By Ory1001 Treatment Both In Vitro And In Vivo, Paving The Way For A New Therapeutic Approach For Type 2 Diabetes Mellitus., The authors are supported by grants from the Consejería de Salud, Fundación Pública Andaluza Progreso y Salud, Junta de Andalucía (PI-0727-2010 and PI-0001-2020 to B.R.G.; PI-0085-2013 to P.I.L.; PI-0006-2016 to E.F.M.; PI-0574-2012 to S.Y.R.Z; PI-0247-2016 to F.J.B.S.), the Consejería de Economía, Innovación y Ciencia (P10.CTS.6359 to B.R.G.; CTS.8081 to E.G.F.), the Ministerio de Economía y Competitividad co-funded by Fondos FEDER (PI10/00871, PI13/00593 and BFU2017-83588-P to B.R.G.; PRE2018-084907 to M.E.M.V.G.; PI13/00309; PI17/01004 to F.J.B.S.; BFU2014-5343-P to J.C.R.; and AGL2017-86927-R to F.M.), Vencer el Cancer (B.R.G), DiabetesCero (B.R.G.) and the Juvenile Diabetes Research Foundation (17-2013-372 and 2-SRA-2019-837-S-B to B.R.G.). E.F.M. was a recipient of a Juan de la Cierva Incorporación Fellowship from the Ministerio de Economía y Competitividad (IJCI-2015-26238). S.Y.R.Z is a recipient of a postdoctoral fellowship from Consejería de Salud, Junta de Andalucía (RH-0070-2013). L.L.N. is supported by a Consejeria de Economia, Conocimiento, Empresas y Universidad postdoctoral fellowship (DOC_00652). F.J.B.S. and E.G.F. are recipients of "Nicolás Monardes" research contracts from Consejería de Salud Junta de Andalucía, (C-0070-2012 and C-0031-2016). A.M.M. is supported by CPII19/00023 and PI18/01590 from the Instituto de Salud Carlos III co-funded by Fondos FEDER. CIBERDEM is an initiative of the Instituto de Salud Carlos III. V.C. is supported by a AECC investigator award.

Diabetes is a chronic metabolic disease caused by an absolute or relative deficiency in functional pancreatic β‐cells that leads to defective control of blood glucose. Current treatments for diabetes, despite their great beneficial effects on clinical symptoms, are not curative treatments, leading to a chronic dependence on insulin throughout life that does not prevent the secondary complications associated with diabetes. The overwhelming increase in DM incidence has led to a search for novel antidiabetic therapies aiming at the regeneration of the lost functional β‐cells to allow the re‐establishment of the endogenous glucose homeostasis. Here we review several aspects that must be considered for the development of novel and successful regenerative therapies for diabetes: first, the need to maintain the heterogeneity of islet β‐cells with several subpopulations of β‐cells characterized by different transcriptomic profiles correlating with differences in functionality and in resistance/behavior under stress conditions; second, the existence of an intrinsic islet plasticity that allows stimulus‐mediated transcriptome alterations that trigger the transdifferentiation of islet non‐β‐cells into β‐cells; and finally, the possibility of using agents that promote a fully functional/mature β‐cell phenotype to reduce and reverse the process of dedifferentiation of β‐cells during diabetes. Authors were/are funded by grants from Consejería de Salud, Fundación Pública Andaluza Progreso y Salud, Junta de Andalucía (PI-0727-2010, December 2010 to B.R.G., PI-0085-2013, December 2013 to P.I.L., and PI-0001-2020, December 2020 to B.R.G. and P.I.L.); Consejería de Economía, Innovación y Ciencia, Junta de Andalucía (P10-CTS-6359 to B.R.G.); Ministerio de Economía y Competitividad, Instituto de Salud Carlos III, cofunded by Fondos FEDER (PI10/00871, January 2011 and PI13/00593, January 2014 to B.R.G.); Ministerio de Economía y Competitividad, Plan Nacional (BFU2017-83588-P, January 2018 to B.R.G. and PRE2018-084907, January 2018 to E.M.-V.); Juvenile Diabetes Research Foundation JDRF (17-2013-372, August 2013 and 2-SRA-2019-837-S-B, August 2019 to B.R.G:); and Fundacion Vencer el Cancer (to B.R.G.). Special thanks to ALUSVI (Asociación Lucha y Sonríe por la Vida, Pilas), a local Andalusian association, and the Fundacion DiabetesCero for their unconditional financial support.