Altered Mouse Adipose Tissue IGF-1 Expression Influences Glucose Control

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1 Altered Mouse Adipose Tissue IGF-1 Expression Influences Glucose Control Jan Trost Prof. Gudrun A. Brockmann Humboldt Universität zu Berlin Department of Crop and Animal Sciences Breeding Biology and Molecular Genetics

2 HT GHRH Somato- Pituitary statin Introduction IGF-1 [GH] General growth Liver Pancreas [IGF-1] [Ins] WAT Muscle [Glc]

3 Introduction IGF-1 Igf-1 gene in mice is located on chromosome 10 (~ 87,8 87,9 Mb) P1 P2 Exon 1 Exon 2 Exon 3 Exon 4 Exon 5 Exon 6 Class I transcripts C1 Ea C1 Eb Expression of auto and paracrine acting IGF-1 Class II transcripts C2 Ea C2 Eb Expression of endocrine acting IGF-1

4 Introduction Cre-LoxP and Adipose Tissue specific KO of IGF-1 Requirements for adipose tissue specific IGF-1 KO: Cre : recombinase that cuts and merges DNA at specific sequences LoxP: sequence driven cutting targets of Cre ap2: Promotor specific for gene expression in Adipose Tissue (AT) cre CRE LoxP igf1 LoxP

5 Introduction Cre-LoxP and Adipose Tissue specific KO of IGF-1 Requirements for adipose tissue specific IGF-1 KO: Cre : recombinase that cuts and merges DNA at specific sequences LoxP: sequence driven cutting targets of Cre ap2: Promotor specific for gene expression in Adipose Tissue (AT) LoxP igf1 LoxP CRE cre

6 Introduction Cre-LoxP and Adipose Tissue specific KO of IGF-1 Requirements for adipose tissue specific IGF-1 KO: Cre : recombinase that cuts and merges DNA at specific sequences LoxP: sequence driven cutting targets of Cre ap2: Promotor specific for gene expression in Adipose Tissue (AT) WAT CRE CRE ap2 cre ap2 cre

7 Results on B6N Body weight B6N wt vs. ap2 driven adipose tissue specific IGF-1 KO (AT-IGF1-KO) on SMD and HFD males females In AT-IGF1-KO mice no significant reduction of BW, LM, FM compared to wt.

8 Results on B6 Males Glucose tolerance males * Females females Insulin tolerance males females Males Females Males Females * AT-IGF1-KO females: Glucose clearance is delayed on HFD. AT-IGF1-KO males: No significant difference in insulin tolerance on HFD.

9 Results on B6N ap2cre generates only partial KO in adipose tissues Relative transcript amount 2 (-ΔΔct) 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 wt AT-IGF1-KO Igf-1 Inguinal adipose tissue Igf-1 Gonadal adipose tissue * 0,9 * Ea Eb Ea C1 Eb n= 12 n= 10 Relative transcript amount 2 (-ΔΔct) 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 Ea Eb Ea Eb C2 C1 C2 Auto- paracrine Endocrine Auto- paracine Endocrine Autocrine Igf-1 in adipose tissue reduced in AT-IGF1-KO

10 Results on B6N wt IGF-1 Serum protein Relative transcript amount 2 (-ΔΔct) IGF-1 [ng/ml] AT-IGF1-KO 1,2 1 Igf-1 expression in liver * < 0,1 wt n= 12 KO n= ,8 0,6 0,4 0,2 0 n= 56 n= 24 Autocrine Igf-1 in AT reduced in AT-IGF1-KO Liver Igf-1 expression elevated in AT-IGF1-KO Serum IGF-1 unaltered 0 Ea Eb Ea Eb C1 auto-paracrine C2 endocrine

11 Results on B6N wt AT-IGF1-KO

12 AT-IGF1-KO in Berlin Fatmouse Imbed line Berlin Fat Mouse Inbred Line 860 (BFMI860) Higher body weight, body fat+ and lean mass compared to B6 general higher fat mass lean mass marginally increased 1 in spite of high fatness not deficient in blood glucose control 2;3 but high blood levels of insulin and high blood levels of IGF-1 BFMI * * BFMI B6 1: Wagener, Asja et al.; Physiol Genomics 27: , : Hantschel, Claudia et al.; Obesity Facts 4: : Schäfer, Nadine et al.; Growth Factors 29(6): , 2011 Hypothesis: Higher effect of AT-IGF1-KO on BFMI due to higher fat mass

13 BW in [g] Results on BFMI Body weight, males n= Age [days] wt 4,5 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 0,0 n=3 KO Organ weights, males * Age 20 weeks * Trends similar to B6N, reduced organ weights in BFMI-KO, except for liver

14 [ng/ml] Results on BFMI Igf-1 relative expression, males, 20 weeks 0,6 0,5 0,4 0,3 0,2 0,1 0 Inguinal adipose tissue Ea Eb C1 Auto- paracrine Ea Eb C2 Endocrine 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 wt n=7 n=3 KO Gonadal adipose tissue Ea Eb C1 Auto- paracrine Ea Eb C2 Endocrine 1 0,8 0,6 0,4 0,2 0 Liver Ea Eb C1 Auto- paracrine Ea Eb C2 Endocrine Serum IGF-1, males, 20 weeks No significant differences in Igf-1 expression or IGF-1 serum levels between KO and wt on BFMI background.

15 Results on BFMI wt n=20 n=4 KO Time [min] Time [min]

16 Discussion/ Outlook Results AT-IGF1-KO KO of IGF1 occurs partialy in AT IGF1 produced in adipose tissue likely contributes to the regulation of glucose homeostasis Effects in the first place on HFD and in fat mice compared to SMD More animals and adipose tissue wide KO are needed to confirm the effects A safe KO in the adipose tissue with another Cre mouse will be generated

17 Acknowledgemends Thanks to GRK1208 and DFG for funding The mice being sacrificed for my researches

18 Acknowledgemends Thanks to the whole Group of Professor Brockmann

19 Thank you for your attention