TWEAK/Fn14 promotes the proliferation and collagen synthesis of rat cardiac fibroblasts via the NF-кB pathway.

We wished to elucidate a potential role of the tumor necrosis factor-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor-inducible molecule 14 (Fn14) axis in myocardial fibrosis. Stimulation of neonatal rat cardiac fibroblasts (CFs) with TWEAK could increase CFs numbers and collagen synthesis. Conversely, when CFs were pretreated with siRNA against Fn14, induction of cell proliferation and collagen synthesis by TWEAK were inhibited. Pretreatment with TWEAK on CFs induced activation of the nuclear factor-kappaB (NF-кB) pathway and subsequently increased the production of metalloproteinase-9 (MMP-9). Cell treatment with siRNA against Fn14 led to inhibition of the NF-кB pathway. Additionally, after stimulation of cell with ammonium pyrrolidine dithiocarbamate, cell proliferation and collagen synthesis induced by NF-кB and the upregulation of MMP-9 production were inhibited. The present study suggested that the TWEAK/Fn14 axis increased cell proliferation and collagen synthesis by activating the NF-кB pathway and increasing MMP-9 activity. This axis may be important for regulating myocardial fibrosis.

[Adult oviposition and larvae feeding behavior of Spodoptera litura (Lepidoptera: Noctuidae) on tobacco plants after infested by B-biotype Bemisia tabaci (Homoptera: Aleyrodidae)].

To understand the effects of the defense responses of tobacco plants induced by the infesting of B-biotype Bemisia tabaci to Spodoptera litura, and to explore the mechanisms of the interspecific interactions between B-biotype B. tabaci and S. litura, a laboratory experiment was conducted to study the effects of tobacco plants after infested by B-biotype B. tabaci on the adult oviposition selection and the larvae feeding, anti-feeding, and other feeding behaviors of S. litura. Comparing with that on control plants, the egg number oviposited by adult S. litura on the infested plants decreased by 40.9%. The plant leaves infested had great repellent effect to the newly-hatched S. litura larvae, while the middle leaves and the leaves with systemic damage symptom (white-vein) had definite attractive effect. Unexpanded terminal leaves had no effects on the host selection of S. litura larvae. The S. litura larvae had significant anti-feeding behavior on the leaves infested, being more notable than that on the leaves with white-vein. On the leaves infested and with white-vein, the feeding times per unit duration or the feeding percentage of S. litura larvae decreased, the time of initiating feeding prolonged, and the total feeding area declined significantly, compared with the control. In conclusion, the tobacco plants after infested by B-biotype B. tabaci had negative effects on the adult oviposition and larvae feeding of S. litura, and the results of the study would be useful in understanding the population dynamics of tobacco pests and their management.