The cyclic AMP-responsive element-binding protein H (CREBH, encoded by CREB3L3) is a membrane-bound transcriptional factor that primarily localizes in the liver and small intestine. CREBH governs triglyceride metabolism in the liver, which mediates the changes in gene expression governing fatty acid oxidation, ketogenesis, and apolipoproteins upregulating LPL activity. A deficiency of CREBH in mice leads to severe hypertriglyceridemia. CREBH, in synergy with PPARα, has a crucial role in upregulating Fgf21 expression, which is implicated in metabolic homeostasis. CREBH binds to and functions as a co-activator for both PPARα and LXRα in regulating gene expression of lipid metabolism. Furthermore, intestinal CREBH in overexpression reduces cholesterol absorption and suppresses high-cholesterol diet-induced fatty liver. Conversely, a deficiency of CrebH in mice fed on various high-fat diets leads to severe fatty liver. Thus, CREBH could be a therapeutic target in the treatment of metabolic diseases.

Non-alcoholic fatty liver disease (NAFLD) has emerged as a significant liver ailment attributed to factors like obesity and diabetes. While ongoing research explores treatments for NAFLD, further investigation is imperative to address this escalating health concern. NAFLD manifests as hepatic steatosis, precipitating insulin resistance and metabolic syndrome. This study aims to validate the regenerative potential of chimeric fibroblast growth factor 21 (FGF21)-Hepatocyte Growth Factor Receptor (HGFR) in NAFLD-afflicted liver cells. AML12, a murine hepatocyte cell line, was utilized to gauge the regenerative effects of chimeric FGF21/HGFR expression. Polysaccharide accumulation was affirmed through periodic acid-Schiff (PAS) staining, while LDL uptake was microscopically observed with labeled LDL. mRNA analysis via RT-PCR revealed reduced expression of key NAFLD markers, including acetyl-CoA carboxylase 1 (ACC1) and sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP), alongside elevated levels of hepatocyte growth factor (HGF), hepatocyte nuclear factor 4 alpha (HNF4A), and albumin (ALB). These findings affirm the hepatoregenerative properties of chimeric FGF21/HGFR within AML12 cells, opening novel avenues for NAFLD therapeutic exploration.

Non-alcoholic steatohepatitis (NASH) is a complex disease resulting from chronic liver injury associated with obesity, type 2 diabetes, and inflammation. Recently, multi-target drugs have been proposed to treat complex diseases including NASH; however, their manufacturing pro-cesses remain time- and cost-intensive and inefficient. Therefore, to overcome these limitations, we developed UniStac, a novel enzyme-mediated conjugation platform for multi-specific drug development. UniStac demonstrated high conjugation yields, optimal thermal stabilities, and robust biological activities. Through such platform, we designed a tetra-specific compound, C-192, targeting Glucagon-like peptide 1 (GLP-1), Glucagon (GCG), Fibroblast growth factor 21 (FGF21), and Interleukin-1 receptor antagonist (IL-1RA) simultaneously for the treatment of NASH. The biological activity and treatment efficacy of C-192 were confirmed both in vitro and in vivo using a methionine–choline-deficient (MCD) diet-induced mouse model. C-192 exhibited profound therapeutic efficacies compared to conventional drugs, including liraglutide and dulaglutide. C-192 significantly improved alanine transaminase levels, triglyceride accumula-tion, and the non-alcoholic fatty liver disease activity score. Our results collectively provide clin-ical feasibility of UniStac for developing multi-specific drugs, and C-192 as an innovative thera-peutic opportunity for severe NASH, as it exerts synergistic effects across multiple targets.