TMEM43-S358L mutation enhances NF-κB-TGFβ signal cascade in arrhythmogenic right ventricular dysplasia/cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a genetic cardiac muscle disease that accounts for approximately 30% sudden cardiac death in young adults. The Ser358Leu mutation of transmembrane protein 43 (TMEM43) was commonly identified in the patients of highly lethal and fully penetrant ARVD subtype, ARVD5. Here, we generated TMEM43 S358L mouse to explore the underlying mechanism. This mouse strain showed the classic pathologies of ARVD patients, including structural abnormalities and cardiac fibrofatty. TMEM43 S358L mutation led to hyper-activated nuclear factor κB (NF-κB) activation in heart tissues and primary cardiomyocyte cells. Importantly, this hyper activation of NF-κB directly drove the expression of pro-fibrotic gene, transforming growth factor beta (TGFβ1), and enhanced downstream signal, indicating that TMEM43 S358L mutation up-regulates NF-κB-TGFβ signal cascade during ARVD cardiac fibrosis. Our study partially reveals the regulatory mechanism of ARVD development.

DISTRIBUTION OF GFP-POSITIVE NEURONS AND THE COLOCALIZATION WITH PARVALBUMIN IN THE CAUDAL SPINAL TRIGEMINAL NUCLEUS IN THE GAD67-GFP KNOCK-IN MOUSE / 解剖学报

Objective To observe the distribution of GABA-containing neurons revealed by GFP expression and the colocalization of the GFP with parvalbumin(PV) in the caudal spinal trigeminal nucleus(Vc),the glutamate decarboxylase 67-green fluorescence protein(GAD67-GFP) knock-in mice were used in the present study. Methods Double-labeled techniques were used by in situ hybridization combined with immunohistochemistry for GFP and double immunofluorescence histochemistry for GFP and NeuN(neuronal nuclei protein,a neuronal marker) or PV.The stained sections were observed under light microscope and a confocal laser-scanning microscope. Results 1.Over 90% of GFP-positive neuronal cell bodies in the laminae Ⅰ and Ⅱ of the Vc showed hybridization signals for GAD67 mRNA,and that almost all neuronal cell bodies with GAD67 mRNA signals were GFP-positive;2.GFP-positive neurons were mainly distributed in the laminae Ⅰ and Ⅱ of the Vc and the vast majority of them were small neurons.The considerable number of GFP-positive processes and somata were most densely observed in the lamina Ⅱ of the Vc.The proportion of GFP-positive neurons in the NeuN-labeled neurons of the Vc was about 19.4% and 24.3% in laminae Ⅰ and Ⅱ,respectively;3.Double-labeled neurons for GFP/PV are mainly found in laminae Ⅰ and Ⅱ of the Vc.The proportion of GFP/PV double-labeled neurons was about 62.4% and 12.8% of total population of PV-and GFP-positive neurons in laminae Ⅰ-Ⅱ of the Vc,respectively.Conclusion GABAergic neurons are mainly distributed in the laminae Ⅰ and Ⅱ of the Vc which related closely to transmission of the nociceptive primary afferent information,and the majority of PV-positive neurons are GABAergic neurons.