late adipogenic and lipogenic genes (ACSL1, FABP4, etc.) Cthrc1 Suppresses White Adipogenic Signaling and Modulates Lipid Composition Siviski, ME1,2 , Jacobs, C2 , Ali, A2 , Kacer, D2 , Jin, Y2 , Wang, Q2 , Vary, C1,2 , Lindner, V1,2 , Prudovsky, I1,2 1Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469  2Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME 04074 Background: Collagen triple helix repeat-containing 1 (Cthrc1) is a novel hypothalamic and pituitary hormone Cthrc1 is a factor in wound healing: it attenuates collagen deposition in the wake of vascular injury Only a small percentage of healthy individuals possess detectable blood plasma levels of Cthrc1 In comparison to wildtype counterparts, Cthrc1-null mice are characterized by fatty liver, increased white fat mass in both subcutaneous and visceral depots, and decreased muscle mass A B CREB pCREB preadipocyte CHOP Treatment: LacZ Cthrc1 pCREB CHOP C/EBPδ C/EBPβ pC/EBPβ C/EBPδ C/EBPβ CHOP pC/EBPβ pC/EBPα C/EBPα PPARγ C/EBPα Methods and Aims: 3T3L1 preadipocytes were transduced with Cthrc1 or β-galactosidase adenovirus. Cells were then treated with inducers of white adipogenic differentiation (insulin, IBMX, and dexamethasone) in order to study the effect of Cthrc1 on the expression of critical white adipogenic transcription factors Subcutaneous and visceral white adipose depots were ex-tracted from wildtype and Cthrc1-null C57BL/6 male mice and analyzed via mass spectrometry in order to characterize the effect of Cthrc1 on lipid structure and composition late adipogenic and lipogenic genes (ACSL1, FABP4, etc.) pC/EBPα adipocyte PPARγ1/2 Figure 2. Cthrc1 attenuates the expression of adipogenic transcription factors and upregulates CHOP. A) Schematic of adipogenic transcription factor signaling central to white preadipocyte-to-adipocyte differentiation, including CHOP (C/EBP homologous protein), a negative regulator of adipogenesis that functions by heterodimerizing with other C/EBP family members. B) Protein (western blot) data from 3T3L1 preadipocytes chemically differentiated up to 7 days. pCREB, C/EBPδ, C/EBPβ, pC/EBPβ, and CHOP data are from cells collected after 2 days of differentiation. C/EBPα, pC/EBPα, and PPARγ data refer to 4 days of differentiation, and ACSL1 data refer to 7 days of differentiation. Prior to differentiation, cells were transduced with either Cthrc1 or β-galactosidase (LacZ) adenovirus. ACSL1 CHOP β-actin Figure 1. Cthrc1-induced suppression of white adipogenic differentiation. Oil Red O staining of 7-day chemically differentiated 3T3L1 cells transduced with either (A) LacZ or (B) Cthrc1. C) Oil Red O absorbance data (*p = 0.0064). A 500 B Retroperitoneal Results: Cthrc1 suppresses both white adipogenic differentiation and the expression of critical white adipogenic transcription factors Cthrc1 upregulates CHOP, a negative regulator of white adipogenic differentiation Cthrc1modulates the lipid composition of white adipose depots by suppressing unsaturated long-chain fatty acid triglyceride levels in retroperitoneal adipose tissue, and suppressing specific sphingomyelin, ganglioside, and hexa-ceramide lipid species in inguinal adipose tissue 10000 Inguinal 400 8000 (Cthrc1 KO – WT) Difference 300 (Cthrc1 KO – WT) Difference A B 6000 200 4000 100 2000 SM 42:2;2 TAG 52:9 GM1 40:0;3 HexCer 40:1;2 C * TAG 54:5 (-FA 18:1) TAG 54:6 (-FA 18:2) TAG 54:4 (-FA 18:1) Future Directions: Determine the mechanism by which Cthrc1 suppresses white adipogenic differentiation and the centrality of CHOP in this context Identify the Cthrc1 receptor(s) Characterize the mechanism(s) by which Cthrc1 modulates the lipid composition of subcutaneous and visceral white adipose depots TAG 54:5 (-FA 18:2) Figure 3. Cthrc1 modulates lipid composition. Mass spectrometry lipidomic profiles of the lipids most upregulated in the Cthrc1-null mouse with respect to the (A) inguinal and (B) retroperitoneal white adipose depots. SM (sphingomyelin); TAG (triacylglyceride); GM1 (monosialotetrahexosylganglioside); HexCer (hexa-ceramide). arbitrary units LacZ Cthrc1