Rab27a GTPase and its effector Myosin Va are host factors required for efficient Oropouche virus cell egress.

Oropouche fever, a debilitating illness common in South America, is caused by Oropouche virus (OROV), an arbovirus. OROV belongs to the Peribunyaviridae family, a large group of RNA viruses. Little is known about the biology of Peribunyaviridae in host cells, especially assembly and egress processes. Our research reveals that the small GTPase Rab27a mediates intracellular transport of OROV induced compartments and viral release from infected cells. We show that Rab27a interacts with OROV glycoproteins and colocalizes with OROV during late phases of the infection cycle. Moreover, Rab27a activity is required for OROV trafficking to the cell periphery and efficient release of infectious particles. Consistently, depleting Rab27a's downstream effector, Myosin Va, or inhibiting actin polymerization also hinders OROV compartments targeting to the cell periphery and infectious viral particle egress. These data indicate that OROV hijacks Rab27a activity for intracellular transport and cell externalization. Understanding these crucial mechanisms of OROV's replication cycle may offer potential targets for therapeutic interventions and aid in controlling the spread of Oropouche fever.

Impact of kinesin Eg5 inhibition by 3,4-dihydropyrimidin-2(1H)-one derivatives on various breast cancer cell features.

BACKGROUND: Breast cancer is a complex heterogeneous disease and is one of the leading causes of death among women. In addressing the need for treatments of this life-threatening illness, we studied 3,4-dihydropyrimidin-2(1H)-one (or thione) derivatives (DHPMs), a class of inhibitor molecules of the Eg5 motor spindle protein that shows pronounced antitumor activity against several cancer cell lines. METHODS: An in vitro screening was performed for identification of DHPMs with potent antitumor effects on MCF-7 and MDA-MB-231 cells and the selected DHPMs were evaluated for their inhibitory activity on Eg5 both in silico, using Molecular dynamics, and in vitro Eg5 inhibition assays. Analysis of cell death induction, proliferation, cell cycle and cancer stem cells (CSC) profile were performed by flow cytometry to assess the influence of the selected DPHMs on these important tumor features. Finally, the effects of DHPM treatment on tube formation were evaluated in vitro using HUVEC cells, and in vivo using a model on chorioallantoic membrane (CAM) of fertilized eggs. RESULTS: We identified five DHPMs with pronounced inhibitory activity on Eg5 motor protein interfering with the proper mitotic spindle assembly during cell division. These compounds impair the correct conclusion of cell cycle of the breast cancer cells and showed to be selective for tumor cells. Moreover, DHPMs modulate the CD44(+)/CD24(-) phenotype leading to a decrease in the CSC population in MDA-MB-231 cells, an important effect since CSC are resistant to many conventional cancer therapies and play a pivotal role in tumor initiation and maintenance. This observation was confirmed by the results which demonstrated that DHPM treated cells had impaired proliferation and were unable to sustain angiogenesis events. Finally, the DHMP treated cells were induced to apoptosis, which is one of the most pursued goals in drug development. CONCLUSIONS: The results of our study strongly suggest that DHPMs inhibit important tumorigenic features of breast cancer cells leading them to death by apoptosis. These findings firmly point to DHPM molecular architecture as a promising alternative against breast cancer.