Professor Shanta Persaud
Professor of Diabetes & Endocrinology
Division of Diabetes & Nutritional Sciences
School of Medicine
King's College London
2.9N Hodgkin Building
London SE1 1UL
Tel: +44 20-7848 6275
Fax: +44 20-7848 6280
BSc Physiology and Pharmacology, First Class, 1986
PhD (London), Physiology, 1989
Stimulus-response coupling in pancreatic β-cells
My research interests are directed towards defining signal transduction pathways involved in the regulated secretion of insulin from pancreatic β-cells. Techniques used by members of my group include isolation of islets of Langerhans from experimental animals; cell culture; measurement of apoptosis by caspase assays and DNA laddering; measurement of ATP and NAD(P)H generation; detection of cell proliferation by BrdU incorporation into DNA; transient and stable transfection of cells; isolation and analysis of RNA and DNA; quantitative and single cell RT-PCR; differential gene expression using gene chip arrays; calcium microfluorimetry; dynamic hormone secretion in perifusion; measurement of hormone and cyclic nucleotide levels by RIA; immunocyto/histochemistry; Western blotting of PAGE-fractionated proteins; measurement of serine/threonine and tyrosine kinase activities in situ and in vitro.
Role of cannabinoid receptors in islet function
There have been recent reports that islets express Gi/o-protein coupled cannabinoid receptors (CB1R and CB2R), but there is no consensus on the receptor subtypes expressed by β-cells and the functional effects of their activation. We have investigated CB receptor expression and function in rodent β-cells and islets. RT-PCR, Western blotting and immunohistochemistry indicated that CB1R and CB2R mRNAs and proteins are expressed byMIN6 and mouse islet β-cells. Activation of cannabinoid receptors with the endogenous cannabinoid 2-AG, a CB1R-selective agonist (ACEA) or a CB2R-selective agonist (JWH015) induces reversible increases in [Ca2+]i in Fura 2-loaded MIN6 cells and dispersed mouse islet cells. Consistent with their effects on [Ca2+]i, 2-AG, ACEA and JWH015 stimulate reversible increases in insulin secretion from MIN6 cells and islets. We are currently investigating distinct signalling pathways downstream of cannabinoid receptors using islets isolated from CB1R knockout mice (in collaboration with David Baker, QMUL). This work is being carried out by Chen Li.
The role of equilibrative nucleoside transporter 3 (ENT3) in islets
A novel diabetes syndrome termed pigmented ‘hypertrichotic dermatosis with insulin-dependent diabetes’ (PHID) has been linked to mutations in the gene encoding ENT3, a member of the equilibrative nucleoside transporter (ENT) family. We have found that ENT3 is expressed by islet β-cells, where it is localises to mitochondria and we have also shown that decreased ENT activity is associated with β-cell apoptosis. We are studying the requirement of endogenous ENT3 for normal islet function and the consequences of ENT3 silencing in islets and β-cells to determine whether loss of ENT3 impairs insulin secretion and promotes β-cell apoptosis, and whether these effects occur through disruption of mitochondrial activity. Understanding the role of ENT3 in β-cell physiology may provide novel insights into pancreatic function and has implications for developing therapeutic modalities for PHID. In addition, this work has the potential to improve understanding of signalling mechanisms regulating the decreased β-cell mass and function that may occur in type 2 diabetes. This work is a collaboration with Dr. Khalid Hussain (Institute of Child Health) and is being carried out byDr. Bo Liu.
Novel insulin secretagogues
Numerous plants have been used in traditional medicines for the treatment of diabetes and several naturally occurring peptides may activate stimulatory receptors in β-cells. We are examining the therapeutic potential of plant-derived extracts and novel peptides by measuring their effects on dynamic insulin secretion from MIN6 β-cells and isolated mouse and human islets in vitro. We are also studying the intracellular signalling events activated by these novel insulin secretagogues in β-cells and assessing their effects on improving glucose tolerance in mice in vivo. This work is being performed in collaboration with Dr Stefan Amisten (University of Oxford).
Stimulus-response coupling in human islets
Much of the research on intracellular pathways involved in the regulation of insulin secretion is performed on rodent islets or β-cell lines. While there is an overlap in many instances between regulatory mechanisms in rodents and humans, there are some important differences. The only way to define which β-cell signalling systems identified in animal models are also operative in humans is to carry out the experiments using human islets. Through a collaboration with Professor Stephanie Amiel and Dr. Guo Cai Huang at King’s College Hospital, we are using isolated human islets of to determine the signal transduction cascades operative in human β-cells which regulate the exocytotic release of insulin, glucagon and somatostatin.
Kisspeptin expression and function in islets
Kisspeptin is a peptide encoded by the Kiss-1 gene, which plays crucial roles in puberty and reproductive function. We have identified both kisspeptin and its receptor (GPR54) in mouse islets, and shown that kisspeptin potentiates glucose-induced insulin release through PLC- and p44/42 MAPK-dependent pathways. Activation of GPR54 with kisspeptin stimulates reversible increases in [Ca2+]i in Fura-2 loaded dispersed islet cells. We have also detected kisspeptin and GPR54 mRNAs in human islets, and immunohistochemical staining of human pancreas sections and co-staining for endocrine hormones indicates that both kisspeptin and GPR54 are expressed by human β-cells. Perifusion of isolated human islets with kisspeptin potentiates glucose-stimulated increased insulin secretion. These studies are being performed jointly with Professor Peter Jones and are being carried out by Dr. James Bowe and Vicki Foot.
The role of hydroxyacyl-coenzyme A dehydrogenase in insulin secretion
Hyperinsulinaemic hypoglycaemia (HH) is a disorder associated with uncontrolled insulin secretion despite prevailing hypoglycaemia. Some patients with severe protein-sensitive HH have mutations in hydroxyacyl-coenzyme A dehydrogenase (HADH), suggesting that HADH deficiency unmasks a novel biochemical pathway by which amino acids stimulate insulin secretion. We are therefore carrying out experiments to determine the molecular mechanisms underlying dysregulated insulin secretion associated with HADH mutations and understand the biochemical basis of protein sensitivity in these patients. These studies are being carried out by Dr. Amanda Heslegrave in collaboration with Dr. Khalid Hussain (Institute of Child Health).
The research described here has been made possible through generous funding from Ayurvedic Life International, BBSRC, Diabetes UK, The European Foundation for the Study of Diabetes, The Henry Lester Trust Limited, and The Society for Endocrinology.
Hauge-Evans AC, King AJ, Carmignac D, Robinson ICAF, Low MJ, Christie MR, Persaud SJ and Jones PM (2009) Somatostatin secreted by islet β-cells fulfils multiple roles as a paracrine regulator of islet function. Diabetes 58, 403-411
Liu, B, Asare-Anane H, Al-Romaiyan A, Amiel SA, Huang GC, Jones PM and Persaud SJ (2009) Chracterisation of the insulinotropic activity of aqueous extracts of Gymnema sylvestre in mouse β-cells and human islets of Langerhans. Cell Physiol Biochem. 2009;23(1-3):125-32.
Physiol. Biochem. 23, 125-132Bowe JE, King AJ, Kinsey-Jones JS, Foot VL, Li XF, O’Byrne KT, Persaud SJ and Jones PM (2009) Kisspeptin regulates insulin secretion in vivo and in vitro: mechanisms of action. Diabetologia 52, 855-862
Muller D, Jones PM and Persaud SJ (2009) Single cell RT-PCR identification of genes expressed by human islet endocrine cells. Methods in Molecular Biology 560, 73-86
Burns CJ, Courtney ML, Persaud SJ and Jones PM (2009) Stem Cell Therapy for Type 1 Diabetes Mellitus. In: Diabetes Mellitus Research (Editor: MN Huber), Nova Science Publishers, Inc.
Jones PM and Persaud SJ (2010) Islet function and insulin secretion. In: Textbook of Diabetes, Volume 4, Blackwell Scientific Press, UK (Eds Holt, Goldstein, Flyvberg)
Li C, Bowe, JE, Jones PM and Persaud SJ (2010) Expression and function of cannabinoid receptors in mouse islets. Islets (in press)
Al-Romaiyan A, Liu B, Asare-Anane H, Maity CR, Chatterjee SK, Koley N, Biswas T, Chatterji AK, Huang GC, Amiel SA, Persaud SJ and Jones PM (2010) Stimulation of insulin secretion from human islets in vitro and in vivo by Gymnema sylvestre extract. Phytotherapy Research (in press)
Paula FMM, Barbosa HCL, Carneiro EM, Persaud SJ, Gagliardino JJ, Boschero, AC and Souza KLA (2010) Requirement of NFκB signalling pathway for modulation of the cholinergic M3 receptor expression by INGAP polypeptide in insulin-producing cells. European. J. Pharmacol. (in press)
Persaud SJ et al. (2010) Pseudoislets as primary islet replacements for research: report on a symposium at King's College London, London UK. Islets (in press)
Persaud SJ, Liu B and Jones PM (2010) Functional analysis of human islets of Langerhans maintained in culture. In: Human Cell Culture, Methods in Molecular Biology (in press)