Dihydroergotamine ameliorates liver fibrosis by targeting transforming growth factor ß type II receptor.

BACKGROUND: The transforming growth factor ß (TGFß) signaling pathway plays a crucial role in the development of liver fibrosis by activating TGFß type II receptor (TGFßR2), followed by the recruitment of TGFßR1 finally triggering downstream signaling pathway. AIM: To find drugs targeting TGFßR2 that inhibit TGFßR1/TGFßR2 complex formation, theoretically inhibit TGFß signaling pathway, and thereby ameliorate liver fibrosis. METHODS: Food and Drug Administration-approved drugs were screened for binding affinity with TGFßR2 by virtual molecular docking. We identified 6 candidates and further explored their potential by Cell Counting Kit-8 (CCK-8) cell cytotoxic experiment to validate toxicity and titrated the best cellular working concentrations. Next, we further demonstrated the detailed molecular working mechanisms using mutagenesis analysis. Finally, we used a mouse model to investigate its potential anti-liver fibrosis effect. RESULTS: We identified 6 drug candidates. Among these 6 drugs, dihydroergotamine (DHE) shows great ability in reducing fibrotic gene expressions such as collagen, p-SMAD3, and α-SMA in TGFß induced cellular model of liver fibrosis in LX-2 cells. Furthermore, we demonstrated that DHE binds to TGFßR2. Moreover, mutation of Leu27, Phe30, Thr51, Ser52, Ile53, and Glu55 of TGFßR2 disrupted the binding of TGFßR2 with DHE. In addition, DHE significantly improved liver fibrosis, as evidenced by Masson's trichrome staining of liver sections. This is further supported by the width and the velocity of the portal vein, and serum markers of liver function. In line with those observations, DHE also decreased macrophages infiltration and extracellular matrix deposition in the liver. CONCLUSION: DHE alleviates liver fibrosis by binding to TGFßR2 thereby suppressing TGFß signaling pathway. We show here that as far as drug repurposing, DHE has great potential to treat liver fibrosis.

Population genomics reveals that natural variation in PRDM16 contributes to cold tolerance in domestic cattle.

Environmental temperature serves as a major driver of adaptive changes in wild organisms. To discover the mechanisms underpinning cold tolerance in domestic animals, we sequenced the genomes of 28 cattle from warm and cold areas across China. By characterizing the population structure and demographic history, we identified two genetic clusters, i.e., northern and southern groups, as well as a common historic population peak at 30 kilo years ago. Genomic scan of cold-tolerant breeds determined potential candidate genes in the thermogenesis-related pathways that were under selection. Specifically, functional analysis identified a substitution of PRDM16 (p.P779L) in northern cattle, which maintains brown adipocyte formation by boosting thermogenesis-related gene expression, indicating a vital role of this gene in cold tolerance. These findings provide a basis for genetic variation in domestic cattle shaped by environmental temperature and highlight the role of reverse mutation in livestock species.