ABSTRACT
Preliminary research in our laboratory found that compound YZG-330 can reduce mouse body temperature, which could be blocked by adenosine A1 receptor (A1R) antagonist DPCPX. Based on the downstream signaling pathway of the A1R, the mechanism by which YZG-330 lowers body temperature was further studied. The pharmacodynamics of YZG-330 was evaluated by measuring the rectal temperature; expression of the transient receptor potential (TRP) ion channel, the P38 protein and its phosphorylated form in mouse hypothalamic homogenate were detected by Western blotting. A Ca2+ fluorescent probe, Fluo-3AM, was added to cells to detect the effect of YZG-330 on the Ca2+ content of mouse hypothalamic cells. YZG-330 dose-dependently reduced the body temperature in mice, and the selective P38 inhibitor SB-203580 (20 mg·kg-1, i.p.) significantly inhibited the hypothermic effect of YZG-330. A TRPM8 antagonist 2 (0.1 μg per mouse, i.c.v.) markedly attenuated the hypothermic effect of YZG-330 (0.25 or 1 mg·kg-1, i.p.). YZG-330 (2 mg·kg-1, i.p.) significantly increased the phosphorylation of P38, an effect that could be attenuated by the A1R antagonist DPCPX (5 mg·kg-1, i.g.) in mouse hypothalamus. In addition, YZG-330 also prominently enhanced the expression of TRPM8, which could be blocked by SB-203580; YZG-330 (0.1-10 μmol·L-1) increased intracellular Ca2+ concetration in mouse hypothalamic cells in a dose-dependent manner, and was inhibited by the A1R inhibitor DPCPX (0.5 and 1 μmol·L-1) and TRPM8 antagonist 2 (1 μmol·L-1). In conclusion, YZG-330 exerts its hypothermic effect by activating the A1R to promote the phosphorylation of P38 protein and thereby up-regulating the expression and activity of the TRPM8 ion channel, resulting in increased intracellular Ca2+ concentration to stimulate mouse hypothalamus cells to down-regulate body temperature. All animal experiments were approved by the Ethics Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences.
ABSTRACT
Many local sheep breeds in China have poor meat quality. Increasing intramuscular fat (IMF) content can significantly improve the quality of mutton. However, the molecular mechanisms of intramuscular adipocyte formation and differentiation remain unclear. This study compared differences between preadipocytes and mature adipocytes by whole-transcriptome sequencing and constructed systematically regulatory networks according to the relationship predicted among the differentially expressed RNAs (DERs). Sequencing results showed that in this process, there were 1,196, 754, 100, and 17 differentially expressed messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), respectively. Gene Ontology analysis showed that most DERs enriched in Cell Part, Cellular Process, Biological Regulation, and Binding terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that the DERs primarily focused on Focal adhesion, phosphoinositide 3-kinase (PI3K)-Akt, mitogen-activated protein kinase (MAPK), peroxisome proliferator-activated receptor (PPAR) signaling pathways. Forty (40) DERs were randomly selected from the core regulatory network to verify the accuracy of the sequence data. The results of qPCR showed that the DER expression trend was consistent with sequence data. Four novel promising candidate miRNAs (miR-336, miR-422, miR-578, and miR-722) played crucial roles in adipocyte differentiation, and they also participated in multiple and important regulatory networks. We verified the expression pattern of the miRNAs and related pathways' members at five time points in the adipocyte differentiation process (0, 2, 4, 6, 8, 10 days) by qPCR, including miR-336/ACSL4/LncRNA-MSTRG71379/circRNA0002331, miR-422/FOXO4/LncRNA-MSTRG54995/circRNA0000520, miR-578/IGF1/LncRNA-MSTRG102235/circRNA0002971, and miR-722/PDK4/LncRNA-MSTRG107440/circ RNA0002909. In this study, our data provided plenty of valuable candidate DERs and regulatory networks for researching the molecular mechanisms of sheep adipocyte differentiation and will assist studies in improving the IMF.
