LIPIDS AND CELL FUNCTION: a journey into the world of lipids to understand its function in cell physiology

Abstractβ-Cells depend on the islet basement membrane (BM). While some islet BM components are produced by endothelial cells (ECs), the source of others remains unknown. Pancreatic pericytes directly support β-cells through mostly unidentified secreted factors. Thus, we hypothesized that pericytes regulate β-cells through the production of BM components. Here, we show that pericytes produce multiple components of the mouse pancreatic and islet interstitial and BM matrices. Several of the pericyte-produced ECM components were previously implicated in β-cell physiology, including collagen IV, laminins, proteoglycans, fibronectin, nidogen, and hyaluronan. Compared to ECs, pancreatic pericytes produce significantly higher levels of α2 and α4 laminin chains, which constitute the peri-islet and vascular BM. We further found that the pericytic laminin isoforms differentially regulate mouse β-cells. Whereas α2 laminins promoted islet cell clustering, they did not affect gene expression. In contrast, culturing on Laminin-421 induced the expression of β-cell genes, including Ins1, MafA, and Glut2, and significantly improved glucose-stimulated insulin secretion. Thus, alongside ECs, pericytes are a significant source of the islet BM, which is essential for proper β-cell function.

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Persistent expression of HNF6 in islet endocrine cells causes disrupted islet architecture and loss of beta cell function

Development ◽

10.1242/dev.127.13.2883 ◽

2000 ◽

Vol 127 (13) ◽

pp. 2883-2895 ◽

Cited By ~ 2

Author(s):

M. Gannon ◽

M.K. Ray ◽

K. Van Zee ◽

F. Rausa ◽

R.H. Costa ◽

...

Keyword(s):

Beta Cell ◽

Beta Cells ◽

Endocrine Cells ◽

Spatial Organization ◽

Glucose Transporter ◽

Cell Function ◽

Regulatory Element ◽

Cell Physiology ◽

Pancreatic Ducts ◽

And Function

We used transgenesis to explore the requirement for downregulation of hepatocyte nuclear factor 6 (HNF6) expression in the assembly, differentiation, and function of pancreatic islets. In vivo, HNF6 expression becomes downregulated in pancreatic endocrine cells at 18. 5 days post coitum (d.p.c.), when definitive islets first begin to organize. We used an islet-specific regulatory element (pdx1(PB)) from pancreatic/duodenal homeobox (pdx1) gene to maintain HNF6 expression in endocrine cells beyond 18.5 d.p.c. Transgenic animals were diabetic. HNF6-overexpressing islets were hyperplastic and remained very close to the pancreatic ducts. Strikingly, alpha, delta, and PP cells were increased in number and abnormally intermingled with islet beta cells. Although several mature beta cell markers were expressed in beta cells of transgenic islets, the glucose transporter GLUT2 was absent or severely reduced. As glucose uptake/metabolism is essential for insulin secretion, decreased GLUT2 may contribute to the etiology of diabetes in pdx1(PB)-HNF6 transgenics. Concordantly, blood insulin was not raised by glucose challenge, suggesting profound beta cell dysfunction. Thus, we have shown that HNF6 downregulation during islet ontogeny is critical to normal pancreas formation and function: continued expression impairs the clustering of endocrine cells and their separation from the ductal epithelium, disrupts the spatial organization of endocrine cell types within the islet, and severely compromises beta cell physiology, leading to overt diabetes.

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Methods to Investigate miRNA Function: Focus on Platelet Reactivity

Thrombosis and Haemostasis ◽

10.1055/s-0040-1718730 ◽

2020 ◽

Cited By ~ 1

Author(s):

Alix Garcia ◽

Sylvie Dunoyer-Geindre ◽

Richard J. Fish ◽

Marguerite Neerman-Arbez ◽

Jean-Luc Reny ◽

...

Keyword(s):

Cell Function ◽

Platelet Reactivity ◽

Cell Physiology ◽

Plasma Samples ◽

Small Noncoding Rnas ◽

Cellular Processes ◽

Extraction And Purification ◽

Large Panel

AbstractMicroRNAs (miRNAs) are small noncoding RNAs modulating protein production. They are key players in regulation of cell function and are considered as biomarkers in several diseases. The identification of the proteins they regulate, and their impact on cell physiology, may delineate their role as diagnostic or prognostic markers and identify new therapeutic strategies. During the last 3 decades, development of a large panel of techniques has given rise to multiple models dedicated to the study of miRNAs. Since plasma samples are easily accessible, circulating miRNAs can be studied in clinical trials. To quantify miRNAs in numerous plasma samples, the choice of extraction and purification techniques, as well as normalization procedures, are important for comparisons of miRNA levels in populations and over time. Recent advances in bioinformatics provide tools to identify putative miRNAs targets that can then be validated with dedicated assays. In vitro and in vivo approaches aim to functionally validate candidate miRNAs from correlations and to understand their impact on cellular processes. This review describes the advantages and pitfalls of the available techniques for translational research to study miRNAs with a focus on their role in regulating platelet reactivity.

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Physiology of the pancreatic α-cell and glucagon secretion: role in glucose homeostasis and diabetes

Journal of Endocrinology ◽

10.1677/joe-08-0290 ◽

2008 ◽

Vol 199 (1) ◽

pp. 5-19 ◽

Cited By ~ 218

Author(s):

Ivan Quesada ◽

Eva Tudurí ◽

Cristina Ripoll ◽

Ángel Nadal

Keyword(s):

Glucose Homeostasis ◽

Cell Function ◽

Critical Role ◽

Glucagon Secretion ◽

Cell Physiology ◽

Cellular Mechanisms ◽

Multiple Control ◽

Hepatic Glucose ◽

Glucose Synthesis ◽

Blood Glucose Concentrations

The secretion of glucagon by pancreatic α-cells plays a critical role in the regulation of glycaemia. This hormone counteracts hypoglycaemia and opposes insulin actions by stimulating hepatic glucose synthesis and mobilization, thereby increasing blood glucose concentrations. During the last decade, knowledge of α-cell physiology has greatly improved, especially concerning molecular and cellular mechanisms. In this review, we have addressed recent findings on α-cell physiology and the regulation of ion channels, electrical activity, calcium signals and glucagon release. Our focus in this review has been the multiple control levels that modulate glucagon secretion from glucose and nutrients to paracrine and neural inputs. Additionally, we have described the glucagon actions on glycaemia and energy metabolism, and discussed their involvement in the pathophysiology of diabetes. Finally, some of the present approaches for diabetes therapy related to α-cell function are also discussed in this review. A better understanding of the α-cell physiology is necessary for an integral comprehension of the regulation of glucose homeostasis and the development of diabetes.

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Polyamine metabolism and tumorigenesis in the ApcMin/+ mouse

Biochemical Society Transactions ◽

10.1042/bst0350336 ◽

2007 ◽

Vol 35 (2) ◽

pp. 336-339 ◽

Cited By ~ 2

Author(s):

F.G. Berger ◽

D.L. Kramer ◽

C.W. Porter

Keyword(s):

Metabolic Flux ◽

Cell Function ◽

Adenomatous Polyposis Coli Gene ◽

Genetically Engineered ◽

Polyamine Metabolism ◽

Cell Physiology ◽

Tumour Development ◽

Neoplastic Process ◽

Flux Model

While polyamine homoeostasis is clearly important in maintenance of normal cell function, the roles of these cations, as well as the enzymes that regulate their metabolism, in the neoplastic process are not clear. In particular, the polyamine catabolic enzyme SSAT (spermidine/spermine N1-acetyltransferase) seems to have different roles in tumorigenesis, depending upon the particular system being analysed. In attempts to clarify the function of SSAT in tumour development, we have utilized the ApcMin/+ mouse, which carries a mutant allele of the Apc (adenomatous polyposis coli) gene, rendering it susceptible to the formation of multiple adenomas in the small intestine and colon. Using genetically engineered animals (i.e. transgenic and knockout mice), we have shown that SSAT acts as a tumour promoter in the ApcMin/+ model. Modulation of tumorigenesis is not associated with changes in tissue levels of either spermidine or spermine. These findings, along with those made in other animal models of cancer, have prompted us to propose that metabolic flux through the polyamine biosynthetic and catabolic pathways, and the consequent changes in levels of various metabolites within the cell (i.e. the metabolome), is critical to tumour development. The metabolic flux model represents a novel way of thinking about the role of polyamines in cell physiology and the neoplastic process.

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Translational factor eIF4G1 regulates glucose homeostasis and pancreatic β-cell function

10.2337/figshare.13110335.v1 ◽

2020 ◽

Author(s):

Ada Admin ◽

Seokwon Jo ◽

Amber Lockridge ◽

Ramkumar Mohan ◽

Nicholas Esch ◽

...

Keyword(s):

Glucose Homeostasis ◽

Cell Function ◽

Scaffolding Protein ◽

Insulin Content ◽

Insulin Biosynthesis ◽

Cell Physiology ◽

Β Cells ◽

Β Cell ◽

Initiation Complex ◽

Β Cell Function

Protein translation is essential for cell physiology, and dysregulation of this process has been linked to aging-related diseases such as type 2 diabetes. Reduced protein level of a requisite scaffolding protein of the initiation complex, eIF4G1, downstream of nutrients and insulin signaling, is associated with diabetes in both humans and mice. In the present study, we tested the hypothesis that eIF4G1 is critical for β-cell function and glucose homeostasis by genetically ablating eIF4G1 specifically in β-cells <i>in vivo</i> (βeIF4G1KO). Adult male and female βeIF4G1KO mice displayed glucose intolerance but normal insulin sensitivity. β-cell mass was normal under steady state and under metabolic stress by diet-induced obesity, but we observed increases in both proliferation and apoptosis in β-cells of βeIF4G1KO. We uncovered deficits in insulin secretion, partly due to reduced mitochondrial oxygen consumption rate, glucose-stimulated Ca<sup>2+</sup> flux, and reduced insulin content associated with loss of eIF4E, the mRNA 5’-cap binding protein of the initiation complex and binding partner of eIF4G1. Genetic reconstitution of eIF4E in single β-cells or intact islets of βeIF4G1KO mice recovers insulin content, implicating an unexplored role for eIF4G1/eIF4E in insulin biosynthesis. Altogether these data demonstrate an essential role for the translational factor eIF4G1 on glucose homeostasis and β-cell function.

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On the correlation between material-induced cell shape and phenotypical response of human mesenchymal stem cells

10.1101/2020.05.13.093641 ◽

2020 ◽

Author(s):

Aliaksei S Vasilevich ◽

Steven S Vermeulen ◽

Marloes Kamphuis ◽

Nadia Roumans ◽

Said Eroume ◽

...

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Cell Shape ◽

Cell Function ◽

Phenotypic Diversity ◽

Human Mesenchymal Stem Cells ◽

Early Response ◽

Cell Physiology ◽

Cell Shapes ◽

Open Question

Learning rules by which cell shape impacts cell function would enable control of cell physiology and fate in medical applications, particularly, on the interface of cells and material of the implants. We defined the phenotypic response of human bone marrow-derived mesenchymal stem cells (hMSCs) to 2176 randomly generated surface topographies by probing basic functions such as migration, proliferation, protein synthesis, apoptosis, and differentiation using quantitative image analysis. Clustering the surfaces into 28 archetypical cell shapes, we found a very strict correlation between cell shape and physiological response and selected seven cell shapes to describe the molecular mechanism leading to phenotypic diversity. Transcriptomics analysis revealed a tight link between cell shape, molecular signatures, and phenotype. For instance, proliferation is strongly reduced in cells with limited spreading, resulting in down-regulation of genes involved in the G2/M cycle and subsequent quiescence, whereas cells with large filopodia are related to activation of early response genes and inhibition of the osteogenic process. Thus, we have started to unravel the open question of how cell function follows cell shape. This will allow designing implants that can actively regulate cellular, molecular signalling through cell shape. Here we are proposing an approach to tackle this question.

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In vitro Characterization of Insulin−Producing β-Cell Spheroids

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.623889 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yonela Ntamo ◽

Ebrahim Samodien ◽

Joleen Burger ◽

Nolan Muller ◽

Christo J. F. Muller ◽

...

Keyword(s):

Glucose Utilization ◽

Cell Function ◽

3D Culture ◽

Glucose Sensing ◽

Blue Staining ◽

Cell Physiology ◽

Β Cell ◽

3D Spheroids

Over the years, immortalized rodent β-cell lines such as RIN, HIT, MIN, βTC, and INS-1 have been used to investigate pancreatic β-cell physiology using conventional two-dimensional (2D) culture techniques. However, physical and physiological limitations inherent to 2D cell culture necessitates confirmatory follow up studies using sentient animals. Three-dimensional (3D) culture models are gaining popularity for their recapitulation of key features of in vivo organ physiology, and thus could pose as potential surrogates for animal experiments. In this study, we aimed to develop and characterize a rat insulinoma INS-1 3D spheroid model to compare with 2D monolayers of the same cell line. Ultrastructural verification was done by transmission electron microscopy and toluidine blue staining, which showed that both 2D monolayers and 3D spheroids contained highly granulated cells with ultrastructural features synonymous with mature pancreatic β-cells, with increased prominence of these features observed in 3D spheroids. Viability, as assessed by cellular ATP quantification, size profiling and glucose utilization, showed that our spheroids remained viable for the experimental period of 30 days, compared to the limiting 5-day passage period of INS-1 monolayers. In fact, increasing ATP content together with spheroid size was observed over time, without adverse changes in glucose utilization. Additionally, β-cell function, assessed by determining insulin and amylin secretion, showed that the 3D spheroids retained glucose sensing and insulin secretory capability, that was more acute when compared to 2D monolayer cultures. Thus, we were able to successfully demonstrate that our in vitro INS-1 β-cell 3D spheroid model exhibits in vivo tissue-like structural features with extended viability and lifespan. This offers enhanced predictive capacity of the model in the study of metabolic disease, β-cell pathophysiology and the potential treatment thereof.

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On the correlation between material-induced cell shape and phenotypical response of human mesenchymal stem cells

Scientific Reports ◽

10.1038/s41598-020-76019-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Aliaksei S. Vasilevich ◽

Steven Vermeulen ◽

Marloes Kamphuis ◽

Nadia Roumans ◽

Said Eroumé ◽

...

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Cell Shape ◽

Cell Function ◽

Phenotypic Diversity ◽

Human Mesenchymal Stem Cells ◽

Early Response ◽

Cell Physiology ◽

Quantitative Image ◽

Cell Shapes

Abstract Learning rules by which cell shape impacts cell function would enable control of cell physiology and fate in medical applications, particularly, on the interface of cells and material of the implants. We defined the phenotypic response of human bone marrow-derived mesenchymal stem cells (hMSCs) to 2176 randomly generated surface topographies by probing basic functions such as migration, proliferation, protein synthesis, apoptosis, and differentiation using quantitative image analysis. Clustering the surfaces into 28 archetypical cell shapes, we found a very strict correlation between cell shape and physiological response and selected seven cell shapes to describe the molecular mechanism leading to phenotypic diversity. Transcriptomics analysis revealed a tight link between cell shape, molecular signatures, and phenotype. For instance, proliferation is strongly reduced in cells with limited spreading, resulting in down-regulation of genes involved in the G2/M cycle and subsequent quiescence, whereas cells with large filopodia are related to activation of early response genes and inhibition of the osteogenic process. In this paper we were aiming to identify a universal set of genes that regulate the material-induced phenotypical response of human mesenchymal stem cells. This will allow designing implants that can actively regulate cellular, molecular signalling through cell shape. Here we are proposing an approach to tackle this question.

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Implication of Voltage-Gated Potassium Channels in Neoplastic Cell Proliferation

Cancers ◽

10.3390/cancers11030287 ◽

2019 ◽

Vol 11 (3) ◽

pp. 287 ◽

Cited By ~ 18

Author(s):

Clara Serrano-Novillo ◽

Jesusa Capera ◽

Magalí Colomer-Molera ◽

Enric Condom ◽

Joan Ferreres ◽

...

Keyword(s):

Cell Cycle ◽

Potassium Channels ◽

Cell Cycle Progression ◽

Cell Function ◽

Tumor Regression ◽

Resting Potential ◽

Volume Control ◽

Cell Physiology ◽

Cycle Progression ◽

Voltage Gated

Voltage-gated potassium channels (Kv) are the largest group of ion channels. Kv are involved in controlling the resting potential and action potential duration in the heart and brain. Additionally, these proteins participate in cell cycle progression as well as in several other important features in mammalian cell physiology, such as activation, differentiation, apoptosis, and cell volume control. Therefore, Kv remarkably participate in the cell function by balancing responses. The implication of Kv in physiological and pathophysiological cell growth is the subject of study, as Kv are proposed as therapeutic targets for tumor regression. Though it is widely accepted that Kv channels control proliferation by allowing cell cycle progression, their role is controversial. Kv expression is altered in many cancers, and their participation, as well as their use as tumor markers, is worthy of effort. There is an ever-growing list of Kv that remodel during tumorigenesis. This review focuses on the actual knowledge of Kv channel expression and their relationship with neoplastic proliferation. In this work, we provide an update of what is currently known about these proteins, thereby paving the way for a more precise understanding of the participation of Kv during cancer development.

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