OBJECTIVE: To identify whether naringenin plays a protective role during thoracic aneurysm formation in Marfan syndrome. METHODS: To validate the effect of naringenin, Fbn1^C1039G/+ mice, the mouse model of Marfan syndrome, were fed with naringenin, and the disease progress was evaluated. The molecular mechanism of naringenin was further investigated via in vitro studies, such as bioluminescence resonance energy transfer (BRET), atomic force microscope and radioligand receptor binding assay. RESULTS: Six-week-old Fbn1^C1039G/+ mice were fed with naringenin for 20 weeks. Compared with the control group, naringenin significantly suppressed the aortic expansion [Fbn1^C1039G/+ vs. Fbn1^C1039G/++naringenin: (2.49±0.47) mm, n=18 vs. (1.87±0.19) mm, n=22, P < 0.05], the degradation of elastin, and the expression and activity of matrix metalloproteinase 2 (MMP2) and MMP9 in the ascending aorta of Fbn1^C1039G/+ mice. Besides, treatment with naringenin for 6 weeks also attenuated the disease progress among the 20-week-old Fbn1^C1039G/+ mice with established thoracic aortic aneurysms [Fbn1^C1039G/+ vs. Fbn1^C1039G/++naringenin: (2.24±0.23) mm, n=8 vs. (1.90±0.17) mm, n=8, P < 0.05]. To understand the underlying molecular mechanisms, we examined the effects of naringenin on angiotensin Ⅱ type 1 receptor (AT1) signaling and transforming growth factor-β (TGF-β) signaling respectively, which were the dominant signaling pathways contributing to aortopathy in Marfan syndrome as previously reported. The results showed that naringenin decreased angiotensin Ⅱ (Ang Ⅱ)-induced phosphorylation of protein kinase C (PKC) and extracellular regulating kinase 1/2 (ERK1/2) in HEK293A cell overexpressing AT1 receptor. Moreover, naringenin inhibited Ang Ⅱ-induced calcium mobilization and uclear factor of activated T-cells (NFAT) signaling. The internalization of AT1 receptor and its binding to β-arrestin-2 with Ang Ⅱ induction were also suppressed by naringenin. As evidenced by atomic force microscope and radioligand receptor binding assay, naringenin inhibited Ang Ⅱ binding to AT1 receptor. In terms of TGF-β signaling, we found that feeding the mice with naringenin decreased the phosphorylation of Smad2 and ERK1/2 as well as the expression of TGF-β downstream genes. Besides, the serum level of TGF-β was also decreased by naringenin in the Fbn1^C1039G/+ mice. Furthermore, we detected the effect of naringenin on platelet, a rich source of TGF-β, both in vivo and in vitro. And we found that naringenin markedly decreased the TGF-β level by inhibiting the activation of platelet. CONCLUSION Our study showed that naringenin has a protective effect on thoracic aortic aneurysm formation in Marfan syndrome by suppressing both AT1 and TGF-β signaling.
Angiotensin II/metabolism* ; Animals ; Aortic Aneurysm, Thoracic/prevention & control* ; Calcium/metabolism* ; Disease Models, Animal ; Elastin/metabolism* ; Fibrillin-1/metabolism* ; Flavanones ; Marfan Syndrome/metabolism* ; Matrix Metalloproteinase 2 ; Matrix Metalloproteinase 9 ; Mice ; Mice, Inbred C57BL ; Protein Kinase C/metabolism* ; Receptor, Angiotensin, Type 1/metabolism* ; Transforming Growth Factor beta/metabolism* ; Transforming Growth Factors/metabolism* ; beta-Arrestins/metabolism*

The Mediator Complex plays key roles in activating gene transcription in eukaryotes. Mediator of RNA polymerase II transcription subunit 12 homolog (MED12) is a subunit of the Mediator Complex and regulates the activity of the complex. MED12 is involved in a variety of cellular activities, and mutations in MED12 gene impair MED12 activities and are associated with several diseases, including Opitz-Kaveggia syndrome, Lujan syndrome, uterine leiomyomas and prostate cancer. This review will discuss the biological function of MED12 and the relationship between MED12 mutations and diseases.
Agenesis of Corpus Callosum ; genetics ; Anus, Imperforate ; genetics ; Constipation ; genetics ; Craniofacial Abnormalities ; genetics ; Female ; Genetic Predisposition to Disease ; Humans ; Leiomyoma ; genetics ; Male ; Marfan Syndrome ; genetics ; Mediator Complex ; genetics ; metabolism ; Mental Retardation, X-Linked ; genetics ; Muscle Hypotonia ; congenital ; genetics ; Mutation ; Prostatic Neoplasms ; genetics ; Transcription, Genetic ; Uterine Neoplasms ; genetics