Kalirin/Trio Rho GDP/GTP exchange factors regulate proinsulin and insulin secretion

in Journal of Molecular Endocrinology
Correspondence should be addressed to R Kuliawat: regina.kuliawat@einstein.yu.edu
Restricted access

Key features for progression to pancreatic β-cell failure and disease are loss of glucose responsiveness and an increased ratio of secreted proinsulin to insulin. Proinsulin and insulin are stored in secretory granules (SGs) and the fine-tuning of hormone output requires signal-mediated recruitment of select SG populations according to intracellular location and age. The GTPase Rac1 coordinates multiple signaling pathways that specify SG release, and Rac1 activity is controlled in part by GDP/GTP exchange factors (GEFs). To explore the function of two large multidomain GEFs, Kalirin and Trio in β-cells, we manipulated their Rac1-specific GEF1 domain activity by using small-molecule inhibitors and by genetically ablating Kalirin. We examined age-related SG behavior employing radiolabeling protocols. Loss of Kalirin/Trio function attenuated radioactive proinsulin release by reducing constitutive-like secretion and exocytosis of 2-h-old granules. At later chase times or at steady state, Kalirin/Trio manipulations decreased glucose-stimulated insulin output. Finally, use of a Rac1 FRET biosensor with cultured β-cell lines demonstrated that Kalirin/Trio GEF1 activity was required for normal rearrangement of Rac1 to the plasma membrane in response to glucose. Rac1 activation can be evoked by both glucose metabolism and signaling through the incretin glucagon-like peptide 1 (GLP-1) receptor. GLP-1 addition restored Rac1 localization/activity and insulin secretion in the absence of Kalirin, thereby assigning Kalirin’s participation to stimulatory glucose signaling.

 

An official journal of

Society for Endocrinology

Sections

Figures

  • View in gallery

    β-Cells express Kalirin and Trio, two homologous GEFs implicated in secretory granule (SG) maturation and exocytosis. (A) Illustration of the multidomain structure shared by Kalirin and Trio: Sec14, Sec14 homology domain; DH, Dbl homology domain; PH, pleckstrin homology domain; SH3, SRC homology 3 domain, Ig, immunoglobulin domain; FN, fibronectin domain. Major Kalirin and Trio splice variants are shown. Regions recognized by the Kalirin (Sec14) and Trio antibodies (spectrin repeats 5 and 6) or targeted by primer pairs (red arrows) in quantitative PCR (qPCR) reactions are indicated. (B) The relative expression of Kalirin and Trio isoforms in mouse islets, β-cell lines and pituitary as determined by qPCR and normalized to Gapdh. (C) (i) Antiserum to the N-terminus of Kalirin (brackets in A) determines Kalirin distribution within mouse pancreatic islets. Phalloidin stained cortical actin was used to outline cells (red). Insulin positive cells are identified by asterisks and arrows indicate Kalirin positive cells devoid of insulin labeling. (D) Antisera to the N-termini of Kalirin and Trio (brackets in A) determine their cellular localization in βTC3 cells (Kalirin, green; Trio, red). Cells were counter stained with DAPI to visualize nuclei. Arrow indicates Kalirin labeling at cell periphery. (E) Expression of endogenous Kalirin and Trio in β-cell lines was determined by immunoblot. Cell lysates from duplicate wells were normalized to protein concentrations and Gapdh staining served as a loading control.

  • View in gallery

    SG characterization and secretion profiling of human islets demonstrate high ISG content and the presence of ISG-derived, constitutive like vesicular pathway. (A) In the merged image, insulin is stained red, proinsulin green. (B) Electron micrographs confirm the presence of ISGs (white arrows, electron lucent content) and mature β-granules (white filled arrows, electron-dense core surrounded by halo) in human and mouse β-cells. (C) Quantitative evaluation of ISG numbers per β-cell area in human or rodent islets or INS-1 β-cell line reveals statistically significant differences in ISG content (n = 15 cells). Human vs mouse β-cells, P = 0.0003; mouse β-cells vs INS-1 cell line, P = 0.0004. (D) Radiolabeled human islets were chased in 5 mM glucose for the indicated times and immunoprecipitated peptide profiles were determined. Arrowheads indicate intracellular content of proinsulin, conversion intermediates (CI) and insulin. (E) Media content of hormone collected during three sequential 1-h intervals. (F) Pulse chase experiment repeated with islets from a different donor (media, 0–1 h). Subsequent addition of stimulatory glucose (media, 1–2 h stim). (G) After low glucose (5 mM), exocytosis (16 mM glucose) was examined (media, G: 2–3 h stim, or F: 1–2 h stim).

  • View in gallery

    In human islets, hormone release via constitutive-like vesicular traffic or direct granule exocytosis depends on Kalirin/Trio GEF1 domain activity. (A) Radiolabeled human islets were treated or not with the small molecule inhibitor NPPD, then chased; DMSO was the solvent control. Tricine-SDS-PAGE separation of immunoprecipitated insulin-containing peptides shows hormone content of media collected during four sequential 1 h intervals (3 × 5 mM glucose, 1 × 16 mM glucose: stim) or retained in the cell (cell lys). (B) For increased sensitivity of detection, a radioautograph was obtained after long (14 day) exposure. (C) Quantification of CI, Proins and Ins from fluorograms as percent total radioactivity; stars mark significantly altered secretion. (D) Exclusion of fluorogenic peptide (bis-AAF-R110) was used to test cell membrane integrity of healthy cells and fluorescence intensity (Ex/Em: 485 nm/530 nm) was normalized to sample protein content. No differences in fluorescence signal were observed with or without NPPD (human islets and βTC3 cells). Cell permeabilization with saponin served as a positive control. A full color version of this figure is available at https://doi.org/10.1530/JME-18-0048.

  • View in gallery

    Kalirin elimination reproduces the pharmacological GEF1 phenotype of impaired glucose-stimulated insulin secretion with an even stronger impact on ISG exocytosis. (A) For in vivo secretion studies, plasma insulin content prior to or 60 min after an intraperitoneal glucose administration was analyzed using ELISA. (B) Radiolabeled islets (30 min pulse) obtained from WT and Kal-KO mice were chased for three sequential incubations (2 × 5 mM glucose, 1–4 h and 4–5 h, followed by 1 × 16 mM glucose, 5–6 h stim). (C) Quantification of total amount of radioactive insulin recovered with stimulation. (D) To focus on the glucose response of newly synthesized granules, the chase time was shortened to 2 h. (E) Quantification. Release of newly synthesized molecules is reduced with loss of Kalirin. (F) Peptides released into media at 2 or 6 h of chase were quantitated and set up as a ratio (WT/Kal-KO). Results of three secretion experiments done in duplicate were averaged, P = 0.0408. A full color version of this figure is available at https://doi.org/10.1530/JME-18-0048.

  • View in gallery

    Change of ISG size during maturation is Kalirin independent. (A, B and C) Electron micrographs of β-cells from WT (A) and Kal-KO mice (B and C). (A) Electron micrographs of WT or (B) Kal-KO β-cells obtained from the intact fixed pancreatic tissue reveal no differences in SG morphology. (n = 2 animals, tissue from 5 month old female mouse shown). (C) Viewed at higher magnification with particular focus on ISGs in vicinity of the Golgi complex (indicated by arrowheads and G). (D) Quantitative evaluation of beta-cell granule maturation by ultrastructural analyses.

  • View in gallery

    RRP exocytosis bypasses the need for Kalirin. (A) Release of the RRP of granules was tested in vivo. WT and Kal-KO mice were fasted for 6 h and plasma samples were taken prior to (basal) and after a 3 min arginine challenge. No significant differences in basal insulin levels or insulin release were observed between WT and Kal-KO mice in response to arginine administration (n = 7 animals). (B) Islets isolated from WT and Kal-KO mice were exposed for 30 min to 5 mM glucose or stimulatory (11 mM glucose plus 30 mM KCl) conditions. Basal insulin secretion from Kal-KO islets was reduced (WT: 0.24 ± 0.01, vs Kal-KO: 0.12 ± 0.02, P = 0.0002). Kal-KO and WT islets were equally capable of secreting insulin in response to glucose plus KCl (WT: 3.2 ± 0.70, Kal-KO: 3.5 ± 0.46, P = 0.5534).

  • View in gallery

    Drugs targeting Kalirin/Trio GEF1 domain alter Rac1 localization and activity. Simultaneous rescue of Rac1 function and insulin output requires GLP-1 signaling. (A) Rac1 distribution in βTC3 cells (5 mM G, panels ii, and iii; 10 min at 16 mM G, panels ii and iii) relative to the plasma membrane marker NKA (panel i) was determined by immunofluorescence labeling. (B) NKA:Rac1 colocalization at the cell periphery was quantified using CellProfiler and Pearson’s correlation coefficients (PCC) as described in ‘Methods’ section. Data (n ≥ 100 cells per condition) are mean ± s.e.m. PCC values increased with glucose stimulation (16 mM G: 0.84 ± 0.03 vs 5 mM G: 0.22 ± 0.06, P < 0.0001) and were attenuated with ITX3 pretreatment (16 mM G + ITX3: 0.34 + 0.07 vs 5 mM G: 0.22 + 0.06, P = 0.24; vs 16 mM G alone: 0.84 + 0.03, P < 0.0001). No significant differences were observed when GLP-1 plus high glucose were used as stimulus (16 mM G + GLP-1, no ITX3: 0.71 + 0.06, vs 16 mM G + GLP-1, plus ITX3: 0.75 + 0.05, P = .72). (C) Glucose response of a Rac1 FRET reporter. Small squares denote areas that were enlarged and shown as a magnified area in the lower panel. Redistribution of the reporter ± ITX and ± GLP-1 is shown. (D) FRET/donor intensities of the Rac1 FRET reporter within 2.2 µm from the cell’s edge were measured and set up as a ratio to the average FRET/donor intensity in the rest of cell (n = 14/condition). Control vs ITX: P = 0.0027; 16 mM G + GLP-1, P = 0.6663. (E) Secretion studies using static incubations of WT or Kal-KO islets exposed to 5 mM glucose or for 10 min to stimulatory (16 mM glucose or 16 mM glucose plus 10 µM GLP-1) conditions. Control vs Kal-KO: P = 0.0489; 16 mM G + GLP-1, P = 0.0730.

References

AhrenB 2000 Autonomic regulation of islet hormone secretion – implications for health and disease. Diabetologia 43 393410. (https://doi.org/10.1007/s001250051322)

AlarconCLeahyJLSchuppinGTRhodesCJ 1995 Increased secretory demand rather than a defect in the proinsulin conversion mechanism causes hyperproinsulinemia in a glucose-infusion rat model of non-insulin-dependent diabetes mellitus. Journal of Clinical Investigation 95 10321039. (https://doi.org/10.1172/JCI117748)

AoyagiKOhara-ImaizumiMNishiwakiCNakamichiYNagamatsuS 2010 Insulin/phosphatidylinositol 3-kinase pathway accelerates the glucose-induced first phase insulin secretion through TrpV2 recruitment in pancreatic beta-cells. Biochemical Journal 432 375386. (https://doi.org/10.1042/BJ20100864)

AoyagiKOhara-ImaizumiMNishiwakiCNakamichiYUekiKKadowakiTNagamatsuS 2012 Acute inhibition of PI3K-PDK1-Akt pathway potentiates insulin secretion through upregulation of newcomer granule fusions in pancreatic beta-cells. PLoS ONE 7 e47381. (https://doi.org/10.1371/journal.pone.0047381)

ArvanPCastleJD 1987 Phasic release of newly synthesized secretory proteins in the unstimulated rat exocrine pancreas. Journal of Cell Biology 104 243252. (https://doi.org/10.1083/jcb.104.2.243)

ArvanPCastleD 1998 Sorting and storage during secretory granule biogenesis: looking backward and looking forward. Biochemical Journal 332 593610. (https://doi.org/10.1042/bj3320593)

ArvanPKuliawatRPrabakaranDZavackiAMElahiDWangSPilkeyD 1991 Protein discharge from immature secretory granules displays both regulated and constitutive characteristics. Journal of Biological Chemistry 266 1417114174.

AsaharaSShibutaniYTeruyamaKInoueHYKawadaYEtohHMatsudaTKimura-KoyanagiMHashimotoNSakaharaMet al. 2013 Ras-related C3 botulinum toxin substrate 1 (RAC1) regulates glucose-stimulated insulin secretion via modulation of F-actin. Diabetologia 56 10881097. (https://doi.org/10.1007/s00125-013-2849-5)

AsfariMJanjicDMedaPLiGHalbanPAWollheimCB 1992 Establishment of 2-mercaptoethanol-dependent differentiated insulin-secreting cell lines. Endocrinology 130 167178. (https://doi.org/10.1210/endo.130.1.1370150)

BlangyAFortP 2013 Targeting the Dbl and dock-family RhoGEFs: a yeast-based assay to identify cell-active inhibitors of Rho-controlled pathways. Enzymes 33 169191. (https://doi.org/10.1016/B978-0-12-416749-0.00008-7)

BonnemaisonMBackNLinYBonifacinoJSMainsREipperB 2014 AP-1A controls secretory granule biogenesis and trafficking of membrane secretory granule proteins. Traffic 15 10991121. (https://doi.org/10.1111/tra.12194)

BorgonovoBOuwendijkJSolimenaM 2006 Biogenesis of secretory granules. Current Opinion in Cell Biology 18 365370. (https://doi.org/10.1016/j.ceb.2006.06.010)

BouquierNVignalECharrasseSWeillMSchmidtSLeonettiJPBlangyAFortP 2009 A cell active chemical GEF inhibitor selectively targets the Trio/RhoG/Rac1 signaling pathway. Chemistry and Biology 16 657666. (https://doi.org/10.1016/j.chembiol.2009.04.012)

BrayMACarpenterAE 2018 Quality control for high-throughput imaging experiments using machine learning in cellprofiler. Methods in Molecular Biology 1683 89112. (https://doi.org/10.1007/978-1-4939-7357-6_7)

BurgoyneRDMorganA 2003 Secretory granule exocytosis. Physiological Reviews 83 581632. (https://doi.org/10.1152/physrev.00031.2002)

CastleJDCastleAM 1996 Two regulated secretory pathways for newly synthesized parotid salivary proteins are distinguished by doses of secretagogues. Journal of Cell Science 109 25912599.

CastleAMHuangAYCastleJD 2002 The minor regulated pathway, a rapid component of salivary secretion, may provide docking/fusion sites for granule exocytosis at the apical surface of acinar cells. Journal of Cell Science 115 29632973.

CordelieresFPBolteS 2014 Experimenters’ guide to colocalization studies: finding a way through indicators and quantifiers, in practice. Methods in Cell Biology 123 395408. (https://doi.org/10.1016/B978-0-12-420138-5.00021-5)

D’AmbraRSuranaMEfratSStarrRGFleischerN 1990 Regulation of insulin secretion from beta-cell lines derived from transgenic mice insulinomas resembles that of normal beta-cells. Endocrinology 126 28152822. (https://doi.org/10.1210/endo-126-6-2815)

DehghanyJHobothPIvanovaAMziautHMullerAKalaidzidisYSolimenaMMeyer-HermannM 2015 A spatial model of insulin-granule dynamics in pancreatic beta-cells. Traffic 16 797813. (https://doi.org/10.1111/tra.12286)

DunARLordGJWilsonRSKavanaghDMCialowiczKISugitaSParkSYangLSmythAMPapadopulosAet al. 2017 Navigation through the plasma membrane molecular landscape shapes random organelle movement. Current Biology 27 408414. (https://doi.org/10.1016/j.cub.2016.12.002)

DunnKWKamockaMMMcDonaldJH 2011 A practical guide to evaluating colocalization in biological microscopy. American Journal of Physiology: Cell Physiology 300 C723C742. (https://doi.org/10.1152/ajpcell.00462.2010)

EatonBAHaugwitzMLauDMooreHP 2000 Biogenesis of regulated exocytotic carriers in neuroendocrine cells. Journal of Neuroscience 20 73347344. (https://doi.org/10.1523/JNEUROSCI.20-19-07334.2000)

FerraroFMaXMSobotaJAEipperBAMainsRE 2007 Kalirin/Trio Rho guanine nucleotide exchange factors regulate a novel step in secretory granule maturation. Molecular Biology of the Cell 18 48134825. (https://doi.org/10.1091/mbc.e07-05-0503)

FridlyandLEPhilipsonLH 2011 Coupling of metabolic, second messenger pathways and insulin granule dynamics in pancreatic beta-cells: a computational analysis. Progress in Biophysics and Molecular Biology 107 293303. (https://doi.org/10.1016/j.pbiomolbio.2011.09.001)

GaisanoHY 2014 Here come the newcomer granules, better late than never. Trends in Endocrinology and Metabolism 25 381388. (https://doi.org/10.1016/j.tem.2014.03.005)

GalkinVEOrlovaAVosMRSchröderGFEgelmanEH 2015 Near-atomic resolution for one state of F-actin. Structure 23 173182. (https://doi.org/10.1016/j.str.2014.11.006)

GoldGGishizkyMLGrodskyGM 1982 Evidence that glucose ‘marks’ beta cells resulting in preferential release of newly synthesized insulin. Science 218 5658. (https://doi.org/10.1126/science.6181562)

GoldGPouJNowlainRMGrodskyGM 1984 Effects of monensin on conversion of proinsulin to insulin and secretion of newly synthesized insulin in isolated rat islets. Diabetes 33 10191024. (https://doi.org/10.2337/diab.33.11.1019)

GoldGPouJGishizkyMLLandahlHDGrodskyGM 1986 Effects of tolbutamide pretreatment on the rate of conversion of newly synthesized proinsulin to insulin and the compartmental characteristics of insulin storage in isolated rat islets. Diabetes 35 612. (https://doi.org/10.2337/diab.35.1.6)

Greitzer-AntesDXieLQinTXieHZhuDDolaiSLiangTKangFHardyABHeYet al. 2018 Kv2.1 clusters on beta-cell plasma membrane act as reservoirs that replenish pools of newcomer insulin granule through their interaction with syntaxin-3. Journal of Biological Chemistry 293 68936904. (https://doi.org/10.1074/jbc.RA118.002703)

HannaSMiskolciVCoxDHodgsonL 2014 A new genetically encoded single-chain biosensor for Cdc42 based on FRET, useful for live-cell imaging. PLoS ONE 9 e96469. (https://doi.org/10.1371/journal.pone.0096469)

HerringBENicollRA 2016 Kalirin and Trio proteins serve critical roles in excitatory synaptic transmission and LTP. PNAS 113 22642269. (https://doi.org/10.1073/pnas.1600179113)

HodgeRGRidleyAJ 2016 Regulating Rho GTPases and their regulators. Nature Reviews Molecular Cell Biology 17 496510. (https://doi.org/10.1038/nrm.2016.67)

JewellJLLuoWOhEWangZThurmondDC 2008 Filamentous actin regulates insulin exocytosis through direct interaction with Syntaxin 4. Journal of Biological Chemistry 283 1071610726. (https://doi.org/10.1074/jbc.M709876200)

KahnSEHalbanPA 1997 Release of incompletely processed proinsulin is the cause of the disproportionate proinsulinemia of NIDDM. Diabetes 46 17251732. (https://doi.org/10.2337/diab.46.11.1725)

KalwatMAThurmondDC 2013 Signaling mechanisms of glucose-induced F-actin remodeling in pancreatic islet beta cells. Experimental and Molecular Medicine 45 e37. (https://doi.org/10.1038/emm.2013.73)

KinasiewiczAJuszczakMPacheckaJFiedorP 2004 Pancreatic islets isolation using different protocols with in situ flushing and intraductal collagenase injection. Physiological Research 53 327333.

KiralyDDEipper-MainsJEMainsREEipperBA 2010 Synaptic plasticity, a symphony in GEF. ACS Chemical Neuroscience 1 348365. (https://doi.org/10.1021/cn100012x)

KlumpermanJKuliawatRGriffithJMGeuzeHJArvanP 1998 Mannose 6-phosphate receptors are sorted from immature secretory granules via adaptor protein AP-1, clathrin, and syntaxin 6-positive vesicles. Journal of Cell Biology 141 359371. (https://doi.org/10.1083/jcb.141.2.359)

KogelTGerdesHH 2010 Maturation of secretory granules. Results and Problems in Cell Differentiation 50 120. (https://doi.org/10.1007/400_2009_31)

KögelTGerdesH-H 2010 Maturation of secretory granules. In Cellular Peptide Hormone Synthesis and Secretory Pathways pp 120. Eds RehfeldJF & BundgaardJR. Berlin/Heidelberg: Springer. (https://doi.org/10.1007/400_2009_31)

KooTHEipperBADonaldsonJG 2007 Arf6 recruits the Rac GEF Kalirin to the plasma membrane facilitating Rac activation. BMC Cell Biology 8 29. (https://doi.org/10.1186/1471-2121-8-29)

KowluruA 2017 Tiam1/Vav2-Rac1 axis: a tug-of-war between islet function and dysfunction. Biochemical Pharmacology 132 917. (https://doi.org/10.1016/j.bcp.2017.02.007)

KuliawatRArvanP 1992 Protein targeting via the ‘constitutive-like’ secretory pathway in isolated pancreatic islets: passive sorting in the immature granule compartment. Journal of Cell Biology 118 521529. (https://doi.org/10.1083/jcb.118.3.521)

KuliawatRArvanP 1994 Distinct molecular mechanisms for protein sorting within immature secretory granules of pancreatic beta-cells. Journal of Cell Biology 126 7786. (https://doi.org/10.1083/jcb.126.1.77)

KuliawatRKlumpermanJLudwigTArvanP 1997 Differential sorting of lysosomal enzymes out of the regulated secretory pathway in pancreatic beta-cells. Journal of Cell Biology 137 595608. (https://doi.org/10.1083/jcb.137.3.595)

KuliawatRPrabakaranDArvanP 2000 Proinsulin endoproteolysis confers enhanced targeting of processed insulin to the regulated secretory pathway. Molecular Biology of the Cell 11 19591972. (https://doi.org/10.1091/mbc.11.6.1959)

KuliawatRKalininaEBockJFrickerLMcGrawTEKimSRZhongJSchellerRArvanP 2004 Syntaxin-6 SNARE involvement in secretory and endocytic pathways of cultured pancreatic beta-cells. Molecular Biology of the Cell 15 16901701. (https://doi.org/10.1091/mbc.e03-08-0554)

KusminskiCMChenSYeRSunKWangQASpurginSBSandersPEBrozinickJTGeldenhuysWJLiWHet al. 2016 MitoNEET-Parkin effects in pancreatic alpha- and beta-cells, cellular survival, and intrainsular cross talk. Diabetes 65 15341555. (https://doi.org/10.2337/db15-1323)

LeahyJLHalbanPAWeirGC 1991 Relative hypersecretion of proinsulin in rat model of NIDDM. Diabetes 40 985989. (https://doi.org/10.2337/diab.40.8.985)

LiJLuoRKowluruALiG 2004 Novel regulation by Rac1 of glucose- and forskolin-induced insulin secretion in INS-1 beta-cells. American Journal of Physiology: Endocrinology and Metabolism 286 E818E827. (https://doi.org/10.1152/ajpendo.00307.2003)

LiangTQinTXieLDolaiSZhuDPrenticeKJWheelerMKangYOsborneLGaisanoHY 2017 New roles of syntaxin-1A in insulin granule exocytosis and replenishment. Journal of Biological Chemistry 292 22032216. (https://doi.org/10.1074/jbc.M116.769885)

LillaVWebbGRickenbachKMaturanaASteinerDFHalbanPAIrmingerJC 2003 Differential gene expression in well-regulated and dysregulated pancreatic beta-cell (MIN6) sublines. Endocrinology 144 13681379. (https://doi.org/10.1210/en.2002-220916)

LohYPKimTRodriguezYMCawleyNX 2004 Secretory granule biogenesis and neuropeptide sorting to the regulated secretory pathway in neuroendocrine cells. Journal of Molecular Neuroscience 22 6371. (https://doi.org/10.1385/JMN:22:1-2:63)

LowJTMitchellJMDoOHBaxJRawlingsAZavortinkMMorganGPartonRGGaisanoHYThornP 2013 Glucose principally regulates insulin secretion in mouse islets by controlling the numbers of granule fusion events per cell. Diabetologia 56 26292637. (https://doi.org/10.1007/s00125-013-3019-5)

MainsREKiralyDDEipper-MainsJEMaXMEipperBA 2011 Kalrn promoter usage and isoform expression respond to chronic cocaine exposure. BMC Neuroscience 12 20. (https://doi.org/10.1186/1471-2202-12-20)

MandelaPYankovaMContiLHMaXMGradyJEipperBAMainsRE 2012 Kalrn plays key roles within and outside of the nervous system. BMC Neuroscience 13 136. (https://doi.org/10.1186/1471-2202-13-136)

MargiottaAProgidaCBakkeOBucciC 2017 Rab7a regulates cell migration through Rac1 and vimentin. Biochimica et Biophysica Acta 1864 367381. (https://doi.org/10.1016/j.bbamcr.2016.11.020)

Mauvais-JarvisF 2015 Sex differences in metabolic homeostasis, diabetes, and obesity. Biology of Sex Differences 6 14. (https://doi.org/10.1186/s13293-015-0033-y)

McPhersonCEEipperBAMainsRE 2002 Genomic organization and differential expression of Kalirin isoforms. Gene 284 4151. (https://doi.org/10.1016/S0378-1119(02)00386-4)

McPhersonCEEipperBAMainsRE 2005 Multiple novel isoforms of Trio are expressed in the developing rat brain. Gene 347 125135. (https://doi.org/10.1016/j.gene.2004.12.028)

MeloniARDeYoungMBLoweCParkesDG 2013 GLP-1 receptor activated insulin secretion from pancreatic beta-cells: mechanism and glucose dependence. Diabetes Obesity and Metabolism 15 1527. (https://doi.org/10.1111/j.1463-1326.2012.01663.x)

MessengerSWThomasDDFalkowskiMAByrneJAGorelickFSGroblewskiGE 2013 Tumor protein D52 controls trafficking of an apical endolysosomal secretory pathway in pancreatic acinar cells. American Journal of Physiology: Gastrointestinal and Liver Physiology 305 G439G452. (https://doi.org/10.1152/ajpgi.00143.2013)

MessengerSWFalkowskiMAThomasDDJonesEKHongWGaisanoHYBoulisNMGroblewskiGE 2014 Vesicle associated membrane protein 8 (VAMP8)-mediated zymogen granule exocytosis is dependent on endosomal trafficking via the constitutive-like secretory pathway. Journal of Biological Chemistry 289 2804028053. (https://doi.org/10.1074/jbc.M114.593913)

MessengerSWThomasDDCooleyMMJonesEKFalkowskiMAAugustBKFernandezLAGorelickFSGroblewskiGE 2015 Early to late endosome trafficking controls secretion and zymogen activation in rodent and human pancreatic acinar cells. Cellular and Molecular Gastroenterology and Hepatology 1 695709. (https://doi.org/10.1016/j.jcmgh.2015.08.002)

MessengerSWJonesEKHolthausCLThomasDDHCooleyMMByrneJAMareninovaOAGukovskayaASGroblewskiGE 2017 Acute acinar pancreatitis blocks vesicle-associated membrane protein 8 (VAMP8)-dependent secretion, resulting in intracellular trypsin accumulation. Journal of Biological Chemistry 292 78287839. (https://doi.org/10.1074/jbc.M117.781815)

MillerMBYanYEipperBAMainsRE 2013 Neuronal Rho GEFs in synaptic physiology and behavior. Neuroscientist 19 255273. (https://doi.org/10.1177/1073858413475486)

MillerMBVishwanathaKSMainsREEipperBA 2015 An N-terminal amphipathic helix binds phosphoinositides and enhances kalirin Sec14 domain-mediated membrane interactions. Journal of Biological Chemistry 290 1354113555. (https://doi.org/10.1074/jbc.M115.636746)

MillerMBYanYMachidaKKiralyDDLevyADWuYILamTTAbbottTKoleskeAJEipperBAet al. 2017a Brain region and isoform-specific phosphorylation alters Kalirin SH2 domain interaction sites and calpain sensitivity. ACS Chemical Neuroscience 8 15541569. (https://doi.org/10.1021/acschemneuro.7b00076)

MillerMBYanYWuYHaoBMainsREEipperBA 2017b Alternate promoter usage generates two subpopulations of the neuronal RhoGEF Kalirin-7. Journal of Neurochemistry 140 889902. (https://doi.org/10.1111/jnc.13749)

MiskolciVWuBMoshfeghYCoxDHodgsonL 2016 Optical tools to study the isoform-specific roles of small GTPases in immune cells. Journal of Immunology 196 34793493. (https://doi.org/10.4049/jimmunol.1501655)

MiyazakiJArakiKYamatoEIkegamiHAsanoTShibasakiYOkaYYamamuraK 1990 Establishment of a pancreatic beta cell line that retains glucose-inducible insulin secretion: special reference to expression of glucose transporter isoforms. Endocrinology 127 126132. (https://doi.org/10.1210/endo-127-1-126)

MoshfeghYBravo-CorderoJJMiskolciVCondeelisJHodgsonL 2014 A Trio-Rac1-Pak1 signalling axis drives invadopodia disassembly. Nature Cell Biology 16 574586. (https://doi.org/10.1038/ncb2972)

Neerman-ArbezMHalbanPA 1993 Novel, non-crinophagic, degradation of connecting peptide in transformed pancreatic beta cells. Journal of Biological Chemistry 268 1624816252.

NoskeABCostinAJMorganGPMarshBJ 2008 Expedited approaches to whole cell electron tomography and organelle mark-up in situ in high-pressure frozen pancreatic islets. Journal of Structural Biology 161 298313. (https://doi.org/10.1016/j.jsb.2007.09.015)

OrciL 1986 The morphology of proinsulin processing. Annals of the New York Academy of Sciences 488 292316. (https://doi.org/10.1111/j.1749-6632.1986.tb46567.x)

PalamidessiAFrittoliEGarreMFarettaMMioneMTestaIDiasproALanzettiLScitaGDi FiorePP 2008 Endocytic trafficking of Rac is required for the spatial restriction of signaling in cell migration. Cell 134 135147. (https://doi.org/10.1016/j.cell.2008.05.034)

PapadopulosA 2017 Membrane shaping by actin and myosin during regulated exocytosis. Molecular and Cellular Neuroscience 84 9399. (https://doi.org/10.1016/j.mcn.2017.05.006)

Portales-CasamarEBriancon-MarjolletAFromontSTribouletRDebantA 2006 Identification of novel neuronal isoforms of the Rho-GEF Trio. Biology of the Cell 98 183193. (https://doi.org/10.1042/BC20050009)

PorteDJrPupoAA 1969 Insulin responses to glucose: evidence for a two pool system in man. Journal of Clinical Investigation 48 23092319. (https://doi.org/10.1172/JCI106197)

RobertsonRPRaymondRHLeeDSCalleRAGhoshASavagePJShankarSSVassilevaMTWeirGCFryburgDA 2014 Arginine is preferred to glucagon for stimulation testing of beta-cell function. American Journal of Physiology: Endocrinology and Metabolism 307 E720E727. (https://doi.org/10.1152/ajpendo.00149.2014)

RoderPVWuBLiuYHanW 2016 Pancreatic regulation of glucose homeostasis. Experimental and Molecular Medicine 48 e219. (https://doi.org/10.1038/emm.2016.6)

RorsmanPBraunM 2013 Regulation of insulin secretion in human pancreatic islets. Annual Review of Physiology 75 155179. (https://doi.org/10.1146/annurev-physiol-030212-183754)

RoubtsovaAChamberlandAMarcinkiewiczJEssalmaniRFazelABergeronJJSeidahNGPratA 2015 PCSK9 deficiency unmasks a sex- and tissue-specific subcellular distribution of the LDL and VLDL receptors in mice. Journal of Lipid Research 56 21332142. (https://doi.org/10.1194/jlr.M061952)

RutkaiIDuttaSKatakamPVBusijaDW 2015 Dynamics of enhanced mitochondrial respiration in female compared with male rat cerebral arteries. American Journal of Physiology: Heart and Circulatory Physiology 309 H1490H1500. (https://doi.org/10.1152/ajpheart.00231.2015)

SandoHBorgJSteinerDF 1972 Studies on the secretion of newly synthesized proinsulin and insulin from isolated rat islets of Langerhans. Journal of Clinical Investigation 51 14761485. (https://doi.org/10.1172/JCI106944)

SchaggerH 2006 Tricine-SDS-PAGE. Nature Protocols 1 1622. (https://doi.org/10.1038/nprot.2006.4)

SeaquistERKahnSEClarkPMHalesCNPorteDJrRobertsonRP 1996 Hyperproinsulinemia is associated with increased beta cell demand after hemipancreatectomy in humans. Journal of Clinical Investigation 97 455460. (https://doi.org/10.1172/JCI118435)

SeinoS 2012 Cell signalling in insulin secretion: the molecular targets of ATP, cAMP and sulfonylurea. Diabetologia 55 20962108. (https://doi.org/10.1007/s00125-012-2562-9)

SpieringDHodgsonL 2012 Multiplex imaging of Rho family GTPase activities in living cells. Methods in Molecular Biology 827 215234. (https://doi.org/10.1007/978-1-61779-442-1_15)

SpieringDBravo-CorderoJJMoshfeghYMiskolciVHodgsonL 2013 Quantitative ratiometric imaging of FRET-biosensors in living cells. Methods in Cell Biology 114 593609. (https://doi.org/10.1016/B978-0-12-407761-4.00025-7)

StraubSGSharpGW 2002 Glucose-stimulated signaling pathways in biphasic insulin secretion. Diabetes/Metabolism Research and Reviews 18 451463. (https://doi.org/10.1002/dmrr.329)

ThamsPCapitoK 1999 L-arginine stimulation of glucose-induced insulin secretion through membrane depolarization and independent of nitric oxide. European Journal of Endocrinology 140 8793. (https://doi.org/10.1530/eje.0.1400087)

ToozeSAMartensGJHuttnerWB 2001 Secretory granule biogenesis: rafting to the SNARE. Trends in Cell Biology 11 116122. (https://doi.org/10.1016/S0962-8924(00)01907-3)

TruyenIDe PauwPJorgensenPNVan SchravendijkCUbaniODecochezKVandemeulebrouckeEWeetsIMaoRPipeleersDGet al. 2005 Proinsulin levels and the proinsulin:c-peptide ratio complement autoantibody measurement for predicting type 1 diabetes. Diabetologia 48 23222329. (https://doi.org/10.1007/s00125-005-1959-0)

VeluthakalRMadathilparambilSVMcDonaldPOlsonLKKowluruA 2009 Regulatory roles for Tiam1, a guanine nucleotide exchange factor for Rac1, in glucose-stimulated insulin secretion in pancreatic beta-cells. Biochemical Pharmacology 77 101113. (https://doi.org/10.1016/j.bcp.2008.09.021)

von ZastrowMCastleJD 1987 Protein sorting among two distinct export pathways occurs from the content of maturing exocrine storage granules. Journal of Cell Biology 105 26752684. (https://doi.org/10.1083/jcb.105.6.2675)

WardWKLaCavaECPaquetteTLBeardJCWallumBJPorteDJr 1987 Disproportionate elevation of immunoreactive proinsulin in type 2 (non-insulin-dependent) diabetes mellitus and in experimental insulin resistance. Diabetologia 30 698702. (https://doi.org/10.1007/BF00296991)

WelchHCCoadwellWJStephensLRHawkinsPT 2003 Phosphoinositide 3-kinase-dependent activation of Rac. FEBS Letters 546 9397. (https://doi.org/10.1016/S0014-5793(03)00454-X)

WendlerFToozeS 2001 Syntaxin 6: the promiscuous behaviour of a SNARE protein. Traffic 2 606611. (https://doi.org/10.1034/j.1600-0854.2001.20903.x)

WilsonDFCemberATJMatschinskyFM 2017 The thermodynamic basis of glucose-stimulated insulin release: a model of the core mechanism. Physiological Reports 5 e13327. (https://doi.org/10.14814/phy2.13327)

WuJHFanaroffACSharmaKCSmithLSBrianLEipperBAMainsREFreedmanNJZhangL 2013 Kalirin promotes neointimal hyperplasia by activating Rac in smooth muscle cells. Arteriosclerosis Thrombosis and Vascular Biology 33 702708. (https://doi.org/10.1161/ATVBAHA.112.300234)

XinXFerraroFBackNEipperBAMainsRE 2004 Cdk5 and Trio modulate endocrine cell exocytosis. Journal of Cell Science 117 47394748. (https://doi.org/10.1242/jcs.01333)

YanYEipperBAMainsRE 2015 Kalirin-9 and Kalirin-12 play essential roles in dendritic outgrowth and branching. Cerebral Cortex 25 34873501. (https://doi.org/10.1093/cercor/bhu182)

ZetheliusBBybergLHalesCNLithellHBerneC 2003 Proinsulin and acute insulin response independently predict Type 2 diabetes mellitus in men – report from 27 years of follow-up study. Diabetologia 46 2026. (https://doi.org/10.1007/s00125-002-0995-2)

Index Card

PubMed

Google Scholar

Related Articles

Altmetrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 18 18 18
Full Text Views 22 22 22
PDF Downloads 8 8 8