title: The DNA chaperone HMGB1 potentiates the transcriptional activity of Rel1A in the mosquito Aedes aegypti.
abstract: High Mobility Group protein 1 (HMGB1) is a non-histone, chromatin-associated nuclear protein that functions in regulating eukaryotic gene expression. We investigated the influence and mechanism of action of Aedes aegypti HMGB1 (AaHMGB1) on mosquito Rel1A-mediated transcription from target gene promoters. The DNA-binding domain (RHD) of AaRel1A was bacterially expressed and purified, and AaHMGB1 dramatically enhanced RHD binding to consensus NF-kB/Rel DNA response elements. Luciferase reporter analyses using a cecropin gene promoter showed that AaHMGB1 potentiates the transcriptional activity of AaRel1A in Aag-2 cells. Moreover, overexpression of AaHMGB1 in Aag-2 cells led to an increase in mRNA levels of antimicrobial peptide genes. In vitro GST pull-down assays revealed that the presence of DNA is a pre-requisite for assembly of a possible ternary complex containing DNA, AaHMGB1 and AaRel1A. Notably, DNA bending by AaHMGB1 enhanced the binding of AaRel1A to a DNA fragment containing a putative NF-kB/Rel response element. Importantly, AaHMGB1 was identified as a potential immune modulator in A. aegypti through AaHMGB1 overexpression or RNAi silencing in Aag-2 cells followed by bacterial challenge or through AaHMGB1 RNAi knockdown in mosquitoes followed by Dengue virus (DENV) infection. We propose a model in which AaHMGB1 bends NF-kB/Rel target DNA to recruit and allow more efficient AaRel1A binding to activate transcription of effector genes, culminating in a stronger Toll pathway-mediated response against DENV infection.
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Entomologia Molecular, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Anderson
authors.initials: A
authors.lastname: de Mendonça Amarante
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, United States.
authors.forename: Natapong
authors.initials: N
authors.lastname: Jupatanakul
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Entomologia Molecular, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Isabel Caetano
authors.initials: IC
authors.lastname: de Abreu da Silva
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Entomologia Molecular, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Vitor Coutinho
authors.initials: VC
authors.lastname: Carneiro
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Entomologia Molecular, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Amanda Roberta Revoredo
authors.initials: ARR
authors.lastname: Vicentino
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Entomologia Molecular, Universidade Federal do Rio de Janeiro, Brazil; W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, United States.
authors.forename: George
authors.initials: G
authors.lastname: Dimopolous
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Entomologia Molecular, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Octávio Augusto C
authors.initials: OAC
authors.lastname: Talyuli
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Entomologia Molecular, Universidade Federal do Rio de Janeiro, Brazil. Electronic address: fantappie@bioqmed.ufrj.br.
authors.forename: Marcelo Rosado
authors.initials: MR
authors.lastname: Fantappié
mesh_terms: D000330:Aedes / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D004247:DNA / Q000235:genetics / Q000378:metabolism; D024243:HMGB1 Protein / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism
chemical_list: D024243:HMGB1 Protein; D019476:Insect Proteins; D018832:Molecular Chaperones; D004247:DNA
keywords: Aedes aegypiti; DNA bending; Dengue virus; High mobility group B1 protein; Nf-kB/Rel; Transcription factor