The eukaryotic translation initiation factor 3 subunit L protein interacts with Flavivirus NS5 and may modulate yellow fever virus replication.

BACKGROUND: Yellow fever virus (YFV) belongs to the Flavivirus genus and causes an important disease. An alarming resurgence of viral circulation and the expansion of YFV-endemic zones have been detected in Africa and South America in recent years. NS5 is a viral protein that contains methyltransferase and RNA-dependent RNA polymerase (RdRp) domains, which are essential for viral replication, and the interactions between NS5 and cellular proteins have been studied to better understand viral replication. The aim of this study was to characterize the interaction of the NS5 protein with eukaryotic translation initiation factor 3 subunit L (eIF3L) and to evaluate the role of eIF3L in yellow fever replication. METHODS: To identify interactions of YFV NS5 with cellular proteins, we performed a two-hybrid screen using the YFV NS5 RdRp domain as bait with a human cDNA library, and RNApol deletion mutants were generated and analyzed using the two-hybrid system for mapping the interactions. The RNApol region involved was segmented into three fragments and analyzed using an eIF3L-expressing yeast strain. To map the NS5 residues that are critical for the interactions, we performed site-direct mutagenesis in segment 3 of the interaction domain (ID) and confirmed the interaction using in vitro assays and in vivo coimmunoprecipitation. The significance of eIF3L for YFV replication was investigated using eIF3L overexpression and RNA interference. RESULTS: In this work, we describe and characterize the interaction of NS5 with the translation factor eIF3L. The interaction between NS5 and eIF3L was confirmed using in vitro binding and in vivo coimmunoprecipitation assays. This interaction occurs at a region (the interaction domain of the RNApol domain) that is conserved in several flaviviruses and that is, therefore, likely to be relevant to the genus. eIF3L overexpression and plaque reduction assays showed a slight effect on YFV replication, indicating that the interaction of eIF3L with YFV NS5 may play a role in YFV replication. CONCLUSIONS: Although the precise function of eIF3L on interactions with viral proteins is not entirely understood, these results indicate an interaction of eIF3L with YF NS5 and that eIF3L overexpression facilitates translation, which has potential implications for virus replication.

The maspin expression in canine mammary tumors: an immunohistochemical and molecular study / A expressão do maspin nos tumores mamários caninos: um estudo imuno-histoquímico e molecular

The serpin maspin, a tumor suppressor in breast cancer was described as an inhibitor of cell migration and inducer of cell adhesion between the basement membrane and extracellular matrix resulting in inhibition of tumor metastasis. In contrast, overexpression of maspin is correlated with poor prognosis in other types of cancer. Little is known about expression, regulation and function of maspin in canine mammary tumors. It was demonstrated in this study, a loss of maspin expression in malignant canine mammary cells compared with a pool of normal canine mammary tissue, analyzed by quantitative real-time PCR; weak maspin expression in malignant canine mammary tumors were observed by immunohistochemistry. It was also demonstrated that a correlation with nuclear maspin expression and a good prognosis. It is suggested that maspin could be used as a prognostic marker in canine mammary neoplasia.

O serpin maspin, um supressor tumoral no câncer de mama foi descrito como inibidor de migração celular e indutor de adesão celular entre a membrana basal e a matriz extracelular resultando na inibição da metástase tumoral. Por outro lado, a alta expressão do maspin está relacionada com um mau prognóstico em outros tipos de câncer. Pouco se sabe sobre a expressão, regulação e função do maspin nos tumores mamários caninos. Neste estudo, foi demonstrada uma perda da expressão de maspin nas células mamárias malignas de cães quando comparadas com um pool de tecido mamário normal de cães, analisado por PCR quantitativa em tempo real. Houve uma expressão fraca maspin em preparações de tumores mamários malignos observadas por imuno-histoquímica. Também foi verificado que a expressão nuclear do maspin em tumores mamários caninos está relacionada a um bom prognóstico. Assim, o maspin pode ser utilizado como um marcador prognóstico nas neoplasias mamárias em cães.