Expression of SARS-CoV-2 Entry Factors in the Pancreas of Normal Organ Donors and Individuals with COVID-19

This article is made available for unrestricted research re-use and secondary analysis in any form or be any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Diabetes is associated with increased mortality from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Given literature suggesting a potential association between SARS-CoV-2 infection and diabetes induction, we examined pancreatic expression of angiotensin-converting enzyme 2 (ACE2), the key entry factor for SARS-CoV-2 infection. Specifically, we analyzed five public scRNA-seq pancreas datasets and performed fluorescence in situ hybridization, western blotting, and immunolocalization for ACE2 with extensive reagent validation on normal human pancreatic tissues across the lifespan, as well as those from coronavirus disease 2019 (COVID-19) cases. These in silico and ex vivo analyses demonstrated prominent expression of ACE2 in pancreatic ductal epithelium and microvasculature, but we found rare endocrine cell expression at the mRNA level. Pancreata from individuals with COVID-19 demonstrated multiple thrombotic lesions with SARS-CoV-2 nucleocapsid protein expression that was primarily limited to ducts. These results suggest SARS-CoV-2 infection of pancreatic endocrine cells, via ACE2, is an unlikely central pathogenic feature of COVID-19-related diabetes.We thank the families of the organ donors and autopsy subjects for the gift of tissues. We also thank Jill K. Gregory, CMI (Icahn School of Medicine at Mount Sinai, New York, NY) for preparing the graphical abstract. These efforts were supported by NIH P01 AI042288 and UC4 DK108132 (M.A.A.); JDRF (M.A.A.); NIH R01 DK122160 (M.C.-T.); NIH R01 AI134971 and P30 DK020541 (D.H.); JDRF 3-PDF-2018-575-A-N (V.V.D.H.); R01 DK093954 , R21 DK119800-01A1 , UC4 DK104166 , and U01 DK127786 (C.E.-M.); VA Merit Award I01BX001733 (C.E.-M.); Imaging Core of NIH/ NIDDK P30 DK097512 (C.E.-M.); gifts from the Sigma Beta Sorority , the Ball Brothers Foundation , and the George and Frances Ball Foundation (C.E.-M.); the Network for Pancreatic Organ Donors with Diabetes ( nPOD ; RRID: SCR_014641 ) ( 5-SRA-2018-557-Q-R ); and The Leona M. & Harry B. Helmsley Charitable Trust ( 2018PG-T1D053 ). The authors also wish to acknowledge the Islet and Physiology Core of the Indiana Diabetes Research Center ( P30DK097512 ). The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication

TAT-Mediated Transduction of MafA Protein In Utero Results in Enhanced Pancreatic Insulin Expression and Changes in Islet Morphology

Alongside Pdx1 and Beta2/NeuroD, the transcription factor MafA has been shown to be instrumental in the maintenance of the beta cell phenotype. Indeed, a combination of MafA, Pdx1 and Ngn3 (an upstream regulator of Beta2/NeuroD) was recently reported to lead to the effective reprogramming of acinar cells into insulin-producing beta cells. These experiments set the stage for the development of new strategies to address the impairment of glycemic control in diabetic patients. However, the clinical applicability of reprogramming in this context is deemed to be poor due to the need to use viral vehicles for the delivery of the above factors. Here we describe a recombinant transducible version of the MafA protein (TAT-MafA) that penetrates across cell membranes with an efficiency of 100% and binds to the insulin promoter in vitro. When injected in utero into living mouse embryos, TAT-MafA significantly up-regulates target genes and induces enhanced insulin production as well as cytoarchitectural changes consistent with faster islet maturation. As the latest addition to our armamentarium of transducible proteins (which already includes Pdx1 and Ngn3), the purification and characterization of a functional TAT-MafA protein opens the door to prospective therapeutic uses that circumvent the use of viral delivery. To our knowledge, this is also the first report on the use of protein transduction in utero

Signal transduction mechanisms involved in the proliferation of C6 glioma cells induced by lysophosphatidic acid

We studied pathways involved in the proliferation of rat C6 glioma cells induced by lysophosphatidic acid (LPA), a phospholipid with diverse biological functions. LPA induced a dose-responsive proliferation of C6 cells after 48 h. Proliferation was blocked by inhibitors of the sodium/proton exchanger type 1 (NHE1), Rho-associated kinase, the phosphatidylinositol 3-kinase/Akt pathway (PI3K/Akt), protein kinase C (PKC) and extracellular signal regulated kinase kinase (MEK). Phospho-specific antibodies were used to investigate the pathways involved. LPA induced transient (10 min) phosphorylations of ERK 1/2, Akt and the transcription factor CREB. The LPA-induced phosphorylation of ERK 1/2 and CREB was blocked by inhibition of PI3K, PKC and MEK, but that of Akt was only inhibited by wortmannin, the PI3K inhibitor. Inhibition of Rho kinase or NHE1 did not reduce the LPA-induced phosphorylation of ERK, Akt or CREB. The results were compared with the effects of LPA on transduction pathways in other cell types

Experimental evaluation and computational modeling of the effects of encapsulation on the time-profile of glucose-stimulated insulin release of pancreatic islets

In type 1 diabetic patients, who have lost their ability to produce insulin, transplantation of pancreatic islet cells can normalize metabolic control in a manner that is not achievable with exogenous insulin. To be successful, this procedure has to address the problems caused by the immune and autoimmune responses to the graft. Islet encapsulation using various techniques and materials has been and is being extensively explored as a possible approach. Within this framework, it is of considerable interest to characterize the effect encapsulation has on the insulin response of pancreatic islets. To improve our ability to quantitatively describe the glucose-stimulated insulin release (GSIR) of pancreatic islets in general and of micro-encapsulated islets in particular, we performed dynamic perifusion experiments with frequent sampling. We used unencapsulated and microencapsulated murine islets in parallel and fitted the results with a complex local concentration-based finite element method (FEM) computational model. The high-resolution dynamic perifusion experiments allowed good characterization of the first-phase and second-phase insulin secretion, and we observed a slightly delayed and blunted first-phase insulin response for microencapsulated islets when compared to free islets. Insulin secretion profiles of both free and encapsulated islets could be fitted well by a COMSOL Multiphysics model that couples hormone secretion and nutrient consumption kinetics with diffusive and convective transport. This model, which was further validated and calibrated here, can be used for arbitrary geometries and glucose stimulation sequences and is well suited for the quantitative characterization of the insulin response of cultured, perifused, transplanted, or encapsulated islets. The present high-resolution GSIR experiments allowed for direct characterization of the effect microencapsulation has on the time-profile of insulin secretion. The multiphysics model, further validated here with the help of these experimental results, can be used to increase our understanding of the challenges that have to be faced in the design of bioartificial pancreas-type devices and to advance their further optimization

Biphasic decline of β-cell function with age in euglycemic nonobese diabetic mice parallels diabetes onset

A gradual decline in insulin response is known to precede the onset of type 1 diabetes (T1D). To track age-related changes in the β-cell function of nonobese diabetic (NOD) mice, the most commonly used animal model for T1D, and to establish differences between those who do and do not become hyperglycemic, we performed a long-term longitudinal oral glucose tolerance test (OGTT) study (10-42 weeks) in combination with immunofluorescence imaging of islet morphology and cell proliferation. We observed a clear biphasic decline in insulin secretion (AUC0-30 min ) even in euglycemic animals. A first phase (10-28 weeks) consisted of a relatively rapid decline and paralleled diabetes development in the same cohort of animals. This was followed by a second phase (29-42 weeks) during which insulin secretion declined much slower while no additional animals became diabetic. Blood glucose profiles showed a corresponding, but less pronounced change: the area under the concentration curve (AUC0-150 min ) increased with age, and fit with a bilinear model indicated a rate-change in the trendline around 28 weeks. In control NOD scids, no such changes were observed. Islet morphology also changed with age as islets become surrounded by mononuclear infiltrates, and, in all mice, islets with immune cell infiltration around them showed increased β-cell proliferation. In conclusion, insulin secretion declines in a biphasic manner in all NOD mice. This trend, as well as increased β-cell proliferation, is present even in the NODs that never become diabetic, whereas, it is absent in control NOD scid mice

El Papa-Moscas : periódico satírico: Año VII Número 341 - 1884 Agosto 24

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Estudo da via de transdução de sinal da GTPase RhoA na ativação da enzima NHE1 na linhagem C6 de glioma de rato

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