TY - JOUR
T1 - Chromomycin A2 potently inhibits glucosestimulated insulin secretion from pancreatic β cells
AU - Kalwat, Michael A.
AU - Hwang, In Hyun
AU - Macho, Jocelyn
AU - Grzemska, Magdalena G.
AU - Yang, Jonathan Z.
AU - McGlynn, Kathleen
AU - MacMillan, John B
AU - Cobb, Melanie H
N1 - Funding Information:
We thank current and former members of the Cobb laboratory for helpful discussions. We are grateful to Elizabeth A. McMillan for providing the FUS ION Cytoscape network. Mithramycin was a generous gift from R. Kittler. The M50 Super 8x TOPFlash was a gift from R. Moon (University of Washington, Seattle, WA; Addgene plasmid 12456). Early phases of this work were supported by a National Institutes of Health Ruth L. Kirschstein National Research Service Award DK100113 (M.A. Kalwat) and R01 DK55310 (M.H. Cobb). Other support was provided through National Institutes of Health grants U41 AT008718 (J.B. MacMillan) and R37 DK34128 (M.H. Cobb). We are grateful to the Welch Foundation for funding portions of this project (I1689 to J.B. MacMillan and I1243 to M.H. Cobb). The authors declare no competing financial interests
Publisher Copyright:
© 2018 Kalwat et al.
PY - 2018/12/1
Y1 - 2018/12/1
N2 - Modulators of insulin secretion could be used to treat diabetes and as tools to investigate β cell regulatory pathways in order to increase our understanding of pancreatic islet function. Toward this goal, we previously used an insulin-linked luciferase that is cosecreted with insulin in MIN6 β cells to perform a high-throughput screen of natural products for chronic effects on glucose-stimulated insulin secretion. In this study, using multiple phenotypic analyses, we found that one of the top natural product hits, chromomycin A2 (CMA2), potently inhibited insulin secretion by at least three potential mechanisms: disruption of Wnt signaling, interference of β cell gene expression, and partial suppression of Ca2+ influx. Chronic treatment with CMA2 largely ablated glucose-stimulated insulin secretion even after washout, but it did not inhibit glucose-stimulated generation of ATP or Ca2+ influx. However, by using the KATP channel opener diazoxide, we uncovered defects in depolarization-induced Ca2+ influx that may contribute to the suppressed secretory response. Glucose-responsive ERK1/2 and S6 phosphorylation were also disrupted by chronic CMA2 treatment. By querying the FUS ION bioinformatic database, we revealed that the phenotypic effects of CMA2 cluster with a number of Wnt-GSK3 pathway-related genes. Furthermore, CMA2 consistently decreased GSK3β phosphorylation and suppressed activation of a β-catenin activity reporter. CMA2 and a related compound, mithramycin, are known to have DNA interaction properties, possibly abrogating transcription factor binding to critical β cell gene promoters. We observed that CMA2 but not mithramycin suppressed expression of PDX1 and UCN3. However, neither expression of INSI/II nor insulin content was affected by chronic CMA2. The mechanisms of CMA2-induced insulin secretion defects may involve components both proximal and distal to Ca2+ influx. Therefore, CMA2 is an example of a chemical that can simultaneously disrupt β cell function through both noncytotoxic and cytotoxic mechanisms. Future therapeutic applications of CMA2 and similar aureolic acid analogues should consider their potential effects on pancreatic islet function.
AB - Modulators of insulin secretion could be used to treat diabetes and as tools to investigate β cell regulatory pathways in order to increase our understanding of pancreatic islet function. Toward this goal, we previously used an insulin-linked luciferase that is cosecreted with insulin in MIN6 β cells to perform a high-throughput screen of natural products for chronic effects on glucose-stimulated insulin secretion. In this study, using multiple phenotypic analyses, we found that one of the top natural product hits, chromomycin A2 (CMA2), potently inhibited insulin secretion by at least three potential mechanisms: disruption of Wnt signaling, interference of β cell gene expression, and partial suppression of Ca2+ influx. Chronic treatment with CMA2 largely ablated glucose-stimulated insulin secretion even after washout, but it did not inhibit glucose-stimulated generation of ATP or Ca2+ influx. However, by using the KATP channel opener diazoxide, we uncovered defects in depolarization-induced Ca2+ influx that may contribute to the suppressed secretory response. Glucose-responsive ERK1/2 and S6 phosphorylation were also disrupted by chronic CMA2 treatment. By querying the FUS ION bioinformatic database, we revealed that the phenotypic effects of CMA2 cluster with a number of Wnt-GSK3 pathway-related genes. Furthermore, CMA2 consistently decreased GSK3β phosphorylation and suppressed activation of a β-catenin activity reporter. CMA2 and a related compound, mithramycin, are known to have DNA interaction properties, possibly abrogating transcription factor binding to critical β cell gene promoters. We observed that CMA2 but not mithramycin suppressed expression of PDX1 and UCN3. However, neither expression of INSI/II nor insulin content was affected by chronic CMA2. The mechanisms of CMA2-induced insulin secretion defects may involve components both proximal and distal to Ca2+ influx. Therefore, CMA2 is an example of a chemical that can simultaneously disrupt β cell function through both noncytotoxic and cytotoxic mechanisms. Future therapeutic applications of CMA2 and similar aureolic acid analogues should consider their potential effects on pancreatic islet function.
UR - http://www.scopus.com/inward/record.url?scp=85057755548&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85057755548&partnerID=8YFLogxK
U2 - 10.1085/jgp.201812177
DO - 10.1085/jgp.201812177
M3 - Article
C2 - 30352794
AN - SCOPUS:85057755548
SN - 0022-1295
VL - 150
SP - 1747
EP - 1757
JO - Journal of General Physiology
JF - Journal of General Physiology
IS - 12
ER -