Fig 2: Proposed simplified signaling mechanism for Exendin-4-induced steatosis improvement. Exendin-4 action is mediated by directly binding to the Glucagon-Like Peptide-1 Receptor (GLP-1R) on the plasma membrane. The activation of the GLP-1R, which is coupled positively to the adenylyl cyclase (AC) system, stimulates AC and increases intracellular cAMP and activation of protein kinase A (PKA). The PKA phosphorylates and activates ß-catenin, which is subsequently translocated to the nucleus. Nuclear ß-catenin then binds to T-cell factor (Tcf) to form a bipartite transcription factor and facilitates the positive or negative modulation of the Tcf-dependent genes, leading, among other effects, to reduced expression of the transcription factor Forkhead Box A1 (FOXA1). The lower expression of FOXA1, one of the most effective activators of the human Fatty Acid Binding Protein 1 (FABP1), results in downregulation of FABP1, which leads to reduced uptake and transport of fatty acids and ultimately decreased steatosis.

Fig 3: Exendin-4 affects hepatocyte lipid metabolism genes by stimulating the GLP-1R. HepG2 cells were starved for 6 h and then treated with Oleic acid (OA; 400 µM) for 16 h followed by 3 h treatment with OA with or without exendin-4 (Ex-4; 200 nM). The expression levels of different genes were quantified with qRT-PCR and normalized to the level of ß-actin. (A–C) The mRNA expression levels of FAS (Fatty acid synthase), ACADL (acyl-CoA dehydrogenase long chain), CPT1A (carnitine palmitoyltransferase 1A), SCD1(stearoyl-CoA desaturase), ACC (acetyl-CoA carboxylase alpha), DGAT1 (diacylglycerol O-acyltransferase 1), DGAT2 (diacylglycerol O-acyltransferase 2), SREBP-1 (sterol regulatory element-binding transcription factor 1), PPAR? (peroxisome proliferator-activated receptor-gamma), FABP1(fatty acid-binding protein 1 ), FOXA1 (forkhead box A1), and APOB (apolipoprotein B) after treatment with OA alone or OA + Ex-4. (D) Silencing of GLP-1R. HepG2 cells were transfected with 20 nM siRNA directed against GLP-1R for 24 h , GLP-1R mRNA expression was quantified with qRTPCR. (E,F) GLP-1R proteins expression was quantified with western blot in HepG2. Full-length blots are displayed in Supplementary Fig.S.1. (G,H) mRNA expression levels of PPAR?, FAS, SCD1, DGAT1, and DGAT2 after transfection with scrambled GLP-1R siRNAs. All values are expressed as the mean ± SE (n = 6). * p < 0.05, ** p < 0.01, *** p < 0.001.

Fig 4: Proposed schematic illustrating the effects of gestational exposure to ?9-tetrahydrocannabinol (?9-THC) on the male rat liver. In summary, in utero exposure to ?9-THC led to symmetrical intrauterine growth restriction in the affected offspring, followed by hepatic catch-up growth and increased visceral adiposity during adult life. Male offspring exposed to gestational ?9-THC exhibited increased FABP1 and oxidative stress at three weeks of age, leading to increased de novo lipogenesis at six months. Adult male offspring also demonstrated oxidative stress and mitochondrial dysfunction, which may occur as a result of elevated hepatic triglyceride content. The presence of oxidative stress and mitochondrial dysfunction in combination with downregulated miR-203a-3p and miR-29a/b/c may further promote impaired lipid metabolism of the liver in a positive-feedback manner.

Fig 5: Deletion of Cldn7 affected epithelial cell differentiation in gKO SIs. Detection of (A) enterocytes by FABP-1 immunofluorescent staining, (C) goblet cells by Alcian blue staining, and (E) EE cells by immunofluorescent staining of chromogranin A in PN3 WT and gKO SIs. Images are representative of more than 3 independent experiments. Scale bars: 100 µm. Quantification of the total number and percentage per villus (or crypt–villus) of (B) enterocyte, (D) goblet cells, and (F) EE cells. Each point represents the calculation from 50 crypt–villus in each mouse. n = 5; 2-tailed, unpaired t test; *P < .05, ***P < .001, ****P < .0001, P > .05. (G) Protein expression levels of FABP-1 in 2 representative PN3 WT and gKO SIs were determined by immunoblotting (left) and then quantified (right). n = 4; 2-tailed, unpaired t test, ***P < .001. (H) The qRT-PCR analysis of FABP1, Muc2, and CHGA mRNA in PN3 WT and gKO SIs. n = 5; 2-tailed, paired t test; P < .05, **P < .01, P > .05. Data are represented as means ± SEM. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.