19 research outputs found
Molecular mechanisms involved in the generation of calcium signals in insulin secreting cells
No full textIntracellular Ca 2+ regulates diverse cellular functions in almost all the cells. In the pancreatic ß-cells, Ca 2+ signals are critical for insulin secretion. An increase in the cytoplasmic free Ca 2+ concentration ([Ca 2+ ]i) triggers insulin secretion. Multiple mechanisms increase the [Ca 2+ ]i in the ß-cells, and in this respect depolarization of the plasma membrane and consequent Ca 2+ entry through the voltage-gated Ca 2+ channels is particularly important. For depolarization of ß-cells the closure of KATP channels is essential. In addition, cation channels belonging to Transient Receptor Potential (TRP) family are thought to play important roles in causing depolarization. Previous studies have reported that the Transient Receptor Potential Melastatin-like subtype 5 (TRPM5) channel, a Ca 2+ activated monovalent cation channel, is involved in the stimulus-secretion coupling in the mouse ß-cells. We aimed to study the role of the TRPM5 channel in regulating insulin secretion, and [Ca 2+ ]i in the rat ß-cells. Another focus of this thesis was to evaluate a new human inluinoma cell line as a model for studying Ca 2+ signaling in the ß-cells. Recently a genetically engineered human insulinoma cell line (EndoC-BH1) has been developed. We studied Ca 2+ signaling in the EndoC-BH1 cells, in an attempt to assess whether these cells could be used as a model for this purpose. For inhibiting the TRPM5 channels we used triphenyl phosphine oxide (TPPO), a selective and potent pharmacological inhibitor of the channel. We measured insulin secretion from the islets from Sprague-Dawley rats in batch incubations. For measuring [Ca 2+ ]i from single rat ß-cells and EndoC-BH1 cells, we used fura-2 based ratiometric microfluorometry. We found that TPPO did not inhibit insulin secretion triggered by KCl, or fructose but it significantly reduced insulin secretion in response to glucose, Larginine, and GLP-1. It also significantly inhibited the KATP channel-independent insulin secretion by glucose. TPPO significantly inhibited the [Ca 2+ ]i increase in response to L-arginine. It also inhibited the [Ca 2+ ]i increase triggered by glucose in a KATP channel independent mechanism. However, TPPO did not alter the [Ca 2+ ]i response triggered by KCl, fructose, glucose and GLP-1. We stimulated the EndoC-BH1 cells with gluocse, GLP-1, KCl, carbachol, Larginine, and tolbutamide. These agents that are known to increase [Ca 2+ ]i in the primary ß-cells also increased [Ca 2+ ]i in the these human insulinoma cells. Moreover, we found that GLP-1 was essential for eliciting Ca 2+ response in the EndoC-BH1 cells upon stimulation by tolbutamide and glucose. We conclude that in the rat islets, TRPM5 plays an important role in mediating insulin secretion by glucose, and L-arginine, and in potentiating the glucoseinduced insulin secretion by GLP-1. We also conclude that the EndoC-BH1cells responds by [Ca 2+ ]i increase upon stimulation by several well-known agonists.List of scientific papersI. Krishnan K, Ma Z, Björklund A, Islam M S. Role of transient receptor potential melastatin-like subtype 5 channel in insulin secretion from rat β-cells. Pancreas. [Accepted] https://pubmed.ncbi.nlm.nih.gov/24632551 II. Krishnan K, Ma Z, Björklund A, Islam M S. Calcium signaling in a genetically engineered human pancreatic β-cell line. [Submitted]</p
Reno productive activity of Ipomoea digitata in gentamicin induced kidney dysfunction
No full textKidneys endowed with million units termed as “nephrons†that act as natural sieves. The kidneys provide the final common pathway for the excretion of many drugs and their metabolites and therefore are frequently subjected to high concentrations of potentially toxic substances. Administration of several antibiotics like Gentamicin causes kidney dysfunction. Rats treated with Gentamicin developed significant kidney dysfunction was observed from increased level of urea, creatinine, sodium and decreased level of protein, potassium and non enzymatic antioxidants such as vitamin C and vitamin E. The plant, Ipomoea digitata is found to have nephroprotective activity. --------------------------------------------------------------------------------------------------------*Department of Biochemistry and Chemistry, Faculty of Science, PRIST University, Vallam, Tanjavur – 613 403, Tamilnadu, India**Department of Zoology, Annamalai University, Annamalainagar - 608 002, Tamilnadu, India1Corresponding author, Email: [email protected] This Article As: A. Kalaiselvan, T. Anand and M. Soundararajan.Reno productive activity of Ipomoea digitata in gentamicin induced kidney dysfunction. J. Ecobiotechnol. 2(2): 57-62
Role of TRPV1 channel and P2Y1 receptor in Ca2+ signalling in β-cells : A study by single cell microfluorometry
No full textIncrease in the cytoplasmic Ca2+ concentration ([Ca2+]i) in the β-cells triggers insulin exocytosis. Among the Ca2+ channels present in the plasma membrane, the transient receptor potential (TRP) channels receptors are currently of great interest. The mechanisms by which the extracellular adenosine diphosphate ribose (ADPr) increases the [Ca2+]i is unknown. Our aims were to study the roles of the TRP channels in the tolbutamide induced [Ca2+]i increase and to identify the surface receptor that is activated by ADPr. We used S5 cells, a highly differentiated rat insulinoma cell line, as a model for β-cells. Single cell ratiometric microfluorometry was used to measure the [Ca2+]i changes in the Fura-2 loaded cells. Tolbutamide increased [Ca2+]i in the form of oscillations. After tolbutamide increased [Ca2+]i,capsazepine, a potent blocker of the transient receptor potential vanilloid subtype 1 (TRPV1) channel was added to the β-cells, which reduced the tolbutamide-induced [Ca2+]i increase. capsazepine, N-(p-Amylcinnamoyl) anthranilic acid (ACA), TRPM2 channel blocker, and triphenyl phosphine oxide (TPPO), TRPM5 channel blocker were tested for their effect on potassium chloride (KCl) induced [Ca2+]i response. These blockers did not inhibit the KCl induced [Ca2+]i increase. Adenosine diphosphate ribose (ADPr) increased [Ca2+]i in the form of initial transient peak followed by an elevated plateau. Application of ADPr shortly after a prior application and washout of Adenosine diphosphate (ADP) elicited only small [Ca2+]i increase indicating desensitization of the receptor involved. 2´deoxy-N6-methyladenosine 3´5´bis-phosphate (MRS2179), and chloro N6-methyl-(N)-methanocarba 2´deoxyadenosine 3´5´ bis-phosphate (MRS2279), two selective inhibitors of P2Y1 receptor, abolished the ADPr-induced [Ca2+]i increase. Tolbutamide closes ATP sensitive potassium (KATP) channels. Our results demonstrate that besides the closure of the KATP channels, inward cation currents carried by Ca2+through the TRPV1 channel are necessary for depolarization to the threshold for the activation of the voltage gated calcium channels (VGCC) to increase the [Ca2+]i. Our results also show that ADPr increases [Ca2+]i by activating the P2Y1 receptor
Studies on molecular mechanisms in calcium signaling and cellular energy consumption
No full textIon signaling plays fundamental role in cell survival. Na+ and Ca2+ are critical players in ion signaling. Cells spend the major amount of energy to maintain and regulate Na+ and Ca2+ gradients across the cell membrane. Any disruption in cellular energy consumption by plasma membrane ATPases affects ion signaling and vice versa. This thesis is a combination of four separate research studies. In the first study, We measured ATP consumption dynamics of Na+/K+-ATPase using a genetically encoded fluorescent indicator called Perceval HR. we demonstrate that PercevalHR is an excellent tool to visualize ATP:ADP in mammalian cells. In the second study, We studied the role of calcium signaling and TRP channels in angiotensin II type 1 receptor signaling cascade. We prove that low inhibition of CaV1.2 with physiological and therapeutically relevant concentration of Angiotensin II up regulate AT1R signaling. In the third study, We studied the role of the TRPM5 channel in regulating insulin secretion, and cytoplasmic free calcium concentration in the rat β-cells by usingtriphenyl phosphine oxide, a selective inhibitor of the channel. In the fourth study, We tested whether, the genetically engineered human β-cell line (EndoC-BH1) could be used as models for studying Ca2+signaling in the context of Type II Diabetes. We found that the EndoC-BH1 cells could be a relevant model to study stimulus-secretion coupling and Ca2+ signaling in the human β-cells.QC 20170328</p
Värdedimensionerna av digital hälsa som förändrar hälso-och sjukvården i Sverige
No full textLife expectancy has increased with improvement in healthcare and diseases have become expensive to treat, several actors in digital health are building solutions that can bring different types of business value and solve big problems in healthcare. With healthcare being one of the complex industries due to hard regulations surrounding it, several digital health companies and startups are still struggling to bring their solutions to the market. Even with many reliable technological innovations, several digital health solutions end up failing at the initial stage of execution. There are several factors that owe to the failure of these solutions such as bad market- fit, poor team, regulations and poor business models. This thesis, however, considers the three value dimensions such as value proposition, value creation and value appropriation that are linked to the different components of a business model. This is done through analysis of two case studies from Sweden that have implemented digital health to create and communicate value to their stakeholders. An interview with one of the personnel responsible for the case that has been performed to better understand the implementation of their case. The findings have shown that an innovation can reach a larger mass by identifying and collaborating with a powerful stakeholder with similar problems or needs. The results of this thesis also include recommendations based on the value dimensions for the companies or startups working with digital health. Researchers and practitioners in the field can use them along with other factors to understand value dimensions and their role in creating better business and value for the society.Idag, lever människan längre, mycket tack vare förbättrad hälso- och sjukvård. Samtidigt, har det blivit kostsamt att behandla folksjukdomar. Olika aktörer inom e-hälsa bygger lösningar som kan lösa stora och omfattande samhällsproblem och samtidigt skapa mervärde för näringslivet. Men sjukvården är ytterst komplex med byråkratiska svårigheter och riktlinjer som gör det svårt för flera digitala (e-hälsa) hälsobolag och startups att lansera deras lösningar in i marknaden i rätt tid. Organisationer med bra digitala hälsolösningar har därför misslyckats redan i ett tidigt skede. Det finns flera faktorer som är kopplad till detta som är värt att nämna såsom icke adekvata kompetenser i teamet, svåra regler, dålig marknadsanpassning och affärsmodeller. Denna upphandling överväger tre värdedimensioner i en affärsmodell såsom värdeförslag, värdeskapande och värdetilldelning. Upphandlingen har analyserat två olika studier från Sverige med e-hälsa i fokus, att förstå implementeringen av de tre olika värdedimensionerna. En intervju var utförd med personal som har jobbat med en av de valda fall studierna, gällande implementering. Resultaten har visat sig att innovationerna kan nå en stor skala när man identifierar och samarbetar med en intressent med liknande problemområden. Denna upphandling baseras på värdedimensioner för digitala hälsobolag och startups som arbetar inom (e-hälsa). Forskare och andra yrkesutövare kan använda resultaten från denna upphandling för att få en djupare förståelse av de olika värdedimensionerna inom samhället
Studies on molecular mechanisms in calcium signaling and cellular energy consumption [Elektronisk resurs]
No full textIon signaling plays fundamental role in cell survival. Na+ and Ca2+ are critical players in ion signaling. Cells spend the major amount of energy to maintain and regulate Na+ and Ca2+ gradients across the cell membrane. Any disruption in cellular energy consumption by plasma membrane ATPases affects ion signaling and vice versa. This thesis is a combination of four separate research studies. In the first study, We measured ATP consumption dynamics of Na+/K+-ATPase using a genetically encoded fluorescent indicator called Perceval HR. we demonstrate that PercevalHR is an excellent tool to visualize ATP:ADP in mammalian cells.In the second study, We studied the role of calcium signaling and TRP channels in angiotensin II type 1 receptor signaling cascade. We prove that low inhibition of CaV1.2 with physiological and therapeutically relevant concentration of Angiotensin II up regulate AT1R signaling.In the third study, We studied the role of the TRPM5 channel in regulating insulin secretion, and cytoplasmic free calcium concentration in the rat β-cells by usingtriphenyl phosphine oxide, a selective inhibitor of the channel.In the fourth study, We tested whether, the genetically engineered human β-cell line (EndoC-BH1) could be used as models for studying Ca2+signaling in the context of Type II Diabetes. We found that the EndoC-BH1 cells could be a relevant model to study stimulus-secretion coupling and Ca2+ signaling in the human β-cells.</p
Calcium signaling in a genetically engineered human pancreatic β-cell line
No full textObjectives: The use of primary human β-cells for studying Ca2+ signalingis limited by the scarcity of human pancreatic islets. Rodent insulinomacell lines are widely used, but it is difficult to extrapolate results obtainedfrom rodent cells to human. Recently, a genetically engineered humanβ-cell line EndoC-BH1 has been developed. We have examined whetherthe EndoC-BH1 cells could be used as a model for studying Ca2+ signalingin the β-cells.Methods: We used microscope-based fluorometry to measure cytoplasmicfreeCa2+ concentration from fura-2–loaded single EndoC-BH1 cellscultured on glass cover slips. Ca2+ responses to different agonists of insulinsecretion were studied. Insulin secretion was measured by radioimmunoassay.Results: EndoC-BH1 cells secreted insulin in response to glucose ina dose-dependent manner, and the secretion was enhanced by GLP-1(glucagon-like peptide 1). Glucose, potassium chloride, carbachol, L-arginine,and tolbutamide increased cytoplasmic-free Ca2+ concentration in theEndoC-BH1 cells. We found that GLP-1 was essential for Ca2+ responseto glucose and tolbutamide.Conclusions: We concluded that the EndoC-BH1 cells can be used asmodel cells to study Ca2+ signaling and stimulus-secretion coupling inthe human β-cells.QC 20170328</p
Role of Transient Receptor Potential Melastatin–like Subtype 5 Channel in Insulin Secretion From Rat β-Cells
No full textObjective Several studies have reported that the transient receptor potential melastatin-like subtype 5 (TRPM5) channel, a Ca2+-activated monovalent cation channel, is involved in the stimulus-secretion coupling in the mouse pancreatic beta-cells. We have studied the role of the TRPM5 channel in regulating insulin secretion and cytoplasmic free Ca2+ concentration ([Ca2+](i)) in the rat beta-cells by using triphenylphosphine oxide, a selective inhibitor of the channel. Methods Insulin secretion from islets from Sprague-Dawley rats was measured in batch incubations. Cytoplasmic free Ca2+ concentration was measured from single beta-cells by fura-2-based microfluorometry. Results Triphenylphosphine oxide did not alter insulin secretion and [Ca2+](i) response triggered by KCl or fructose. It inhibited insulin secretion in response to glucose, l-arginine, and glucagon-like peptide 1. It also inhibited glucose-induced insulin secretion by mechanisms that are independent of the adenosine triphosphate-sensitive potassium channels and [Ca2+](i) increase. Conclusions Our results suggest that in the rat islets, TRPM5 is involved in mediating insulin secretion by glucose and l-arginine and in potentiating the glucose-induced insulin secretion by glucagon-like peptide 1.</p
Role of TRPM5 channel in insulin secretion from rat β-cells. [Elektronisk resurs] : TRPM5 and insulin secretion
No full textOBJECTIVE:Several studies have reported that the transient receptor potential melastatin-like subtype 5 (TRPM5) channel, a Ca(2+)-activated monovalent cation channel, is involved in the stimulus-secretion coupling in the mouse pancreatic β-cells. We have studied the role of the TRPM5 channel in regulating insulin secretion and cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) in the rat β-cells by using triphenylphosphine oxide, a selective inhibitor of the channel.METHODS:Insulin secretion from islets from Sprague-Dawley rats was measured in batch incubations. Cytoplasmic free Ca(2+) concentration was measured from single β-cells by fura-2-based microfluorometry.RESULTS:Triphenylphosphine oxide did not alter insulin secretion and [Ca(2+)](i) response triggered by KCl or fructose. It inhibited insulin secretion in response to glucose, L-arginine, and glucagon-like peptide 1. It also inhibited glucose-induced insulin secretion by mechanisms that are independent of the adenosine triphosphate-sensitive potassium channels and [Ca(2+)](i) increase.CONCLUSIONS:Our results suggest that in the rat islets, TRPM5 is involved in mediating insulin secretion by glucose and l-arginine and in potentiating the glucose-induced insulin secretion by glucagon-like peptide 1.</p
Role of TRPM5 channel in insulin secretion from rat β-cells. : TRPM5 and insulin secretion
No full textOBJECTIVE: Several studies have reported that the transient receptor potential melastatin-like subtype 5 (TRPM5) channel, a Ca(2+)-activated monovalent cation channel, is involved in the stimulus-secretion coupling in the mouse pancreatic β-cells. We have studied the role of the TRPM5 channel in regulating insulin secretion and cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) in the rat β-cells by using triphenylphosphine oxide, a selective inhibitor of the channel. METHODS: Insulin secretion from islets from Sprague-Dawley rats was measured in batch incubations. Cytoplasmic free Ca(2+) concentration was measured from single β-cells by fura-2-based microfluorometry. RESULTS: Triphenylphosphine oxide did not alter insulin secretion and [Ca(2+)](i) response triggered by KCl or fructose. It inhibited insulin secretion in response to glucose, L-arginine, and glucagon-like peptide 1. It also inhibited glucose-induced insulin secretion by mechanisms that are independent of the adenosine triphosphate-sensitive potassium channels and [Ca(2+)](i) increase. CONCLUSIONS: Our results suggest that in the rat islets, TRPM5 is involved in mediating insulin secretion by glucose and l-arginine and in potentiating the glucose-induced insulin secretion by glucagon-like peptide 1.QC 20170328</p
