β Cell Generation and Regeneration Michael German, MD UCSF Diabetes Center San Francisco, California

Transcription

1 β Cell Generation and Regeneration Michael German, MD UCSF Diabetes Center San Francisco, California

2 Where do β cells come from? Apoptosis Adult

3 Rfx6 Takeshi Miyatsuka, MD, PhD Stuart Smith, PhD Nina Kishimoto David Scheel

4 Islet Cell Lineages β-cell Neurog3 Rfx6 α-cell duct cell acinar cell

5 Expression Profile of RFX Factors Stuart Smith

6 Rfx6 Expression at E10 Nina Kishimoto

7 Rfx6 Expression Rfx6 E14.5 E18.5 Adult Nina Kishimoto

8 Rfx6 -/- Mice at P1 Stuart Smith & David Scheel

9 Rfx6 -/- Mice at E17.5 Stuart Smith & David Scheel

10 Mitchell-Riley Syndrome Diabetolgia, Am. J. Med. Genetics, 2008.

11 Mutations in Human Patients. 5 Probands tested: 4 Homozygous RFX6 mutations. 1 Compound heterozygote. Splicing site and missense mutations. Arg>Gln Ser>Pro RFX6 DNA BINDING DIMERIZATION RFX6 DNA Binding Wild Type Arg58Gln Constantin Polychronakos Stuart Smith

12 Islet Cell Lineages β-cell Rfx6 Neurog3 Rfx6 α-cell duct cell acinar cell

13 Islet Cell Lineages Nkx2.2 Pax4 Nkx6.1 Insm1 Glis3 Hnf1a Hopx Pax6 Pdx1 Isl1 Lmx1b Sox4 Mnx1 Pet1/Fev Gata6 MafA β-cell Rfx6 Sox17 Glis3 Gata4 Gata6 Hnf1b Foxa Hnf4a Oc1 NeuroD1 NeuroD2 Atoh8 Sim1 Myt1 Neurog3 Sox9 Mnx1 Pdx1 Lmx1a Ptf1a Dach1 Insm1 Rfx6 Snal1/2 Pou3f4 Arx Irx1/2 MafB α-cell Hnf1b Foxa2 Sox9 Hnf6 duct cell Ptf1a Rbpjl Gata4 acinar cell

14 Where do β cells come from? Apoptosis Adult

15 Physiologic Regulators of β Cell Turnover Takeshi Miyatsuka, MD, PhD Miles Berger, MD, PhD Hector Macias- Saldivar, PhD Hail Kim, MD, PhD Nada Nekrep, PhD Chester Chamberlain, PhD Greg Ku, MD, PhD

16 Collaborators UCSF: Miles Berger Larry Tecott Jean Regard Sean Coughlin Bruce Conklin Gail Martin Olov Andersson Didier Stainier KAIST Hail Kim UT Southwestern: Kathleen McGlynn Melanie Cobb Kyorin University: Mica Ohara-Imaizumi Shinya Nagamatsu Juntendo University Yukiko Toyofuku Hirotaka Watada Takeshi Miyatsuka

17 β Cell Proliferation: Signals Metabolic Glucose Lipids Adrenal (cortisol, epinephrine) Adipose (leptin, adiponectin) Gut (GLP1, GIP, gastrin) Bone (osteocalcin) Liver (betatrophin) Pituitary (GH, Prl) Placenta (PL) Endocrine Islet Auto/Paracrine Insulin IAPP ATP IGF2 Adenosine NPY Serotonin Ucn3 Dopamine GABA Acetylcholine VEGF PDGFα Parasympathetic Sympathetic Sensory Enteric Neural

18 Serotonin (5-HT) in mouse islets Insulin 5-HT merge Normal female Pregnant female Nina Kishimoto

19 5-HT Receptors in the Islet β-cell-specific expression Gα i Gα q Ligand-gated cation channel Ha-il Kim

20 5-HTR in islets during pregnancy Karnik, et al., 2007 Ha-il Kim Relative mrna level HTR 2A 5HTR 2B con G6 G9 G12 G15 G18 P7 5HTR 1B 5HTR 1D con G6 G9 G12 G15 G18 P7

21 5-HT receptor inhibitor Ha-il Kim

22 Htr2b KO Islets Ha-il Kim

23 β-cell Population in Pregnancy Placenta Na + β-cell PRLR HTR3A TPH Trp HTR1D HTR2B 5HT proliferation

24 GPCRs Implicated in β-cell Proliferation A. Gα q/11 -linked: Chrm3 Htr2b B. Gα s -linked: Glp1r C. Gα 12/13 -linked:? Gipr Adora2b D. Gα i/o -linked: Htr1d?

25 Gα i/o Signaling: : Increased Islet promoter Wild Type Pancreas GiPCR: Htr1a GiPCR Pancreas Insulin/Glucagon Miles Berger Larry Tecott

26 Gα i/o Signaling: : Increased Miles Berger Larry Tecott

27 Gα i/o Signaling: Increased Insulin promoter Reverse tetracycline transactivator (rtta) rtta dox dox P1-P7 rtta teto binding sites GiPCR: Ro1 Miles Berger Larry Tecott

28 Gα i/o Signaling: Increased Miles Berger Larry Tecott

29 Gα i/o Signaling: Decreased Insulin promoter Reverse tetracycline transactivator (rtta) rtta dox dox P1-P7 rtta teto binding sites Pertussus Toxin Miles Berger Larry Tecott

30 Gα i/o Signaling: Decreased Adult Neonate Miles Berger Larry Tecott

31 β-cell Gα i/o Receptors Greg Ku Hail Kim Takeshi Miyatsuka

32 Neural Regulation of β Cell Mass Phox2b +/+ Phox2b -/- Insulin/Glucagon Nada Nekrep

33 Sympathetic Signals Inhibit Proliferation In vivo Neonatal In vitro Adult islet In vitro Adult islet Takeshi Miyatsuka Hector Macias

34 Ga i/o Signals Induce Apoptosis Ratio TUNEL + Ratio TUNEL + Hector Macias

35 Neural Regulation of β-cell Proliferation Sympathetic Neurons Parasympathetic Neurons αa2 G i β β-cell β G q M3 GalR1 proliferation apoptosis

36 Gα i/o Signaling 2009 QIAGEN, all rights reserved

37 Ga i/o Signaling in the β Cell Hector Macias

38 Chester Chamberlain K-Ras in the β Cell

39 K-Ras in the β Cell Chester Chamberlain

40 K-Ras in the β Cell Chester Chamberlain

41 K-Ras activates diverse effector pathways Malumbres and Barbacid, Nature Reviews Cancer 2002

42 K-Ras in the β Cell Chester Chamberlain

43 RASSF1 Inhibits Proliferation Downstream of Kras Chester Chamberlain

44 K-Ras in the β Cell?

45 Multiple Endocrine Neoplasia Type 1 Autosomal dominant endocrine familial tumor syndrome characterized by tumors of the pancreatic islets (gastrinomas and insulinomas), parathyroids, pituitary, and adrenal cortex and less commonly other neuroendocrine tumors caused by heterozygous inactivating mutations of the MEN1 gene, which encodes the endocrine tumor suppressor Menin.

46 K-Ras in Menin-Sensitive Tissues Chester Chamberlain

47 Menin Controls Kras Outputs Chester Chamberlain

48 Menin Controls Kras Outputs DNA Nkx6.1 EdU Chester Chamberlain

49 K-Ras in the β Cell Gα i/o Signaling?

50 RASSF1 Inhibits Proliferation Downstream of Kras Chester Chamberlain

51 Summary During pregnancy, lactogenic hormones drive β cell serotonin production, which in turn drives β cell expansion. Gα i/o signals, including sympathetic signaling receptors and Htr1d, block proliferation and induce apoptosis in β cells. Alterations in perinatal β cell proliferation have long term effects on β cell mass. Kras signaling paradoxically inhibits β-cell proliferation. Menin acts as a gatekeeper of MAPK regulation of β- cell proliferation. These pathways have consequences for the role of genes, drugs, and stress in type 1 and 2 diabetes and gestational diabetes.

52 Acknowledgements Larry L. Hillblom Foundation NIDDK; Beta-Cell Biology Consortium JDRF ADA Justine K. Schreyer Endowed Chair in Diabetes Research