Effects of Zika virus infection on the localization and processing of the β-amyloid precursor protein

Author(s)

Milena Barrocali de Araújo Melo

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2023-03-09

Examining board members

Luis Lamberti Pinto da Silva; José Luiz Proença Modena; Adriano Silva Sebollela

• Advisor: Luis Lamberti Pinto da Silva

Abstract

The Zika virus (ZIKV) is a flavivirus of medical importance belonging to the Flaviviridae family, whose main transmitting agents are mosquitoes of the Aedes family. Other important arboviruses are included in the genus Flavivirus, the best-known being Dengue virus (DENV) and Yellow Fever virus (YFV). Although of notable relevance in public health due to several reports in the literature correlating this arbovirus to severe clinical manifestations that trigger central nervous system (CNS) involvement, studies that explore the intracellular dynamics of ZIKV, particularly with regard to the participation of factors of the host cell in viral propagation, are scarce. Thus, the first part of this dissertation aimed to investigate the participation of ESCRT machinery (Endosomal Sorting Complex Required for Transport) in the assembly and budding of ZIKV. This machinery is responsible for mediating intracellular events that require membrane deformation and fission and has already been involved in processes that culminate in the assembly and budding of several enveloped viruses, such as some flaviviruses. Through a yeast two-hybrid, we showed that the ZIKV non-structural protein 3 (NS3) interacts with the TSG101 protein (ESCRT-I) via the NS3 helicase domain. The knockdown of TSG101 was performed, by small interfering RNA (siRNA), to understand the importance of this protein during viral infection. The data showed that TSG101 depletion did not compromise the efficiency of viral replication and externalization of infectious ZIKV particles. The ESCRT machinery has also been reported in the literature as being able to regulate β-amyloid Precursor Protein (APP) trafficking. The depletion of ESCRT components resulted in the inhibition of APP degradation and promoted the accumulation of β-amyloid (Aβ), a neurotoxic peptide resulting from the proteolytic cleavage of APP. The ESCRT machinery also plays a role in the process of autophagy, involved in the clearance of the C99 fragment, the precursor of Aβ. Thus, the second part of this dissertation aimed to investigate the effect of ZIKV infection on APP traffic and processing. Our results indicated that ZIKV infection induces changes in the total levels of the APP protein, in addition to causing its intracellular redistribution. In an attempt to elucidate our hypothesis that ZIKV-induced autophagy is responsible for changes in expression, subcellular redistribution and APP processing, the effect of ZIKV proteins NS4A and NS4B (known to induce autophagy), was tested. The data obtained demonstrated that the ZIKV NS4A protein co-localizes strongly with APP and that both viral proteins can modify APP\'s localization and processing, favoring the detection of C99. (AU)

• FAPESP's process: 19/20193-4 - Study of the involvement of ESCRT machinery in the assembly and budding of zika virus in human glioblastoma cells
• Grantee: Milena Barrocali de Araújo Melo
• Support Opportunities: Scholarships in Brazil - Master