Biology subjects

Peterson, A. J.

Publications and source records attributed to Peterson, A. J..

8 recordsLinked to original sources

bioRxiv2026

Sequence Homology and Tissue Tropism Determine Superinfection Exclusion of Zika virus in Aedes aegypti Mediated by an insect-specific Binjari-Zika Virus Chimera

Arboviruses such as dengue, Zika, and chikungunya viruses cause widespread disease and continue to expand their geographical range due to climate change and vector spread. Insect-specific flaviviruses (ISFs) are promising biocontrol candidates of arboviruses, due to recent studies showing that prior infection with an ISF can reduce arbovirus replication in mosquitoes through superinfection exclusion (SIE). However, the route of infection, tissue tropism, pathogenesis and the mechanisms underlying SIE of ISFs in mosquitoes remain unclear. RNA interference (RNAi) is a potent antiviral response in insects, therefore it is expected that sequence homology between the ISF and the arbovirus will strengthen SIE. Here, we used ISF Binjari virus and a chimera containing the Zika virus structural proteins prME (BinJ-ZIKV) as a model system. Intrathoracic injection of BinJ-ZIKV in Aedes aegypti led to rapid systemic infection that excluded the midgut, subsequently blocking ZIKV dissemination from the midgut. SIE was strongest in tissues where primary-virus replication was highest. This spatial component of SIE was stronger when there was sequence homology between the ISF and arbovirus and displayed a strong 21nt siRNA response, suggesting RNAi contributed to the observed SIE. Upon oral inoculation, BinJ-ZIKV replicated efficiently in mosquitoes, was detected across multiple tissues, and saliva. BinJ-ZIKV also had higher infection establishment than BinJV at lower oral titres. SIE was observed for BinJ-ZIKV infection after oral exposure interfered with subsequent ZIKV midgut infection. Together, these findings support engineered ISF-chimeras as valuable experimental tools to dissect viral determinants of SIE and to optimize mosquito-based arbovirus interference strategies. ImportanceAnnually, over 400 million people are infected with mosquito-transmitted viruses. Insect-specific flaviviruses (ISFs) can interfere with the transmission of clinically important viruses through a phenomenon termed superinfection exclusion (SIE). However, the mechanisms of SIE remain poorly understood. Using a Binjari virus chimera expressing Zika virus (ZIKV) structural proteins, we show that SIE is highly tissue-specific, with exclusion of ZIKV only occurring at sites where the chimera actively replicates and induces the mosquito antiviral RNA interference pathway. We further demonstrate that incorporation of Zika virus prM and E proteins into the ISF backbone enhances infection of the mosquito midgut following oral exposure, which enables direct inhibition of ZIKV infection after a subsequent infectious blood meal. Together, these findings define a replication-dependent, tissue-specific mechanism of ISF-mediated protection and provide a framework for reducing mosquito-borne virus transmission through SIE.

microbiology↗

bioRxiv2025

Linking Expression and Function of Drosophila Type-I TGF-b Receptor Baboon Isoforms: Multiple Roles of BaboA Isoform in Shaping of the Adult Central Nervous System

Evolutionarily conserved transforming growth factor {beta} (TGF-{beta}) signaling is used in both vertebrates and invertebrates to regulate a variety of developmental and cellular processes. The baboon (babo) gene encoding a Drosophila type-I TGF-{beta} receptor produces three isoforms via alternative splicing: BaboA, BaboB, and BaboC. In this study, we generated three fly lines, each carrying an isoform-specific GFP tag, and another line with a GFP conjugated at the C-terminus common to all isoforms. Using these lines, we assessed (1) whether the tagged proteins function properly in rescue assays and (2) how the isoform expression is regulated in various tissues including the central nervous system (CNS). A Gal4 knock-in line in the babo locus was also characterized for reporter expression, mutant phenotypes, and isoform-specific knockdown phenotypes. We found that the C-terminal tag does not interrupt the subcellular targeting and functions of the tagged isoforms, but the internal isoform tags do so in a cell- and isoform-specific fashion. Nevertheless, our results demonstrated that these tags faithfully reflect endogenous expression of individual isoforms. Certain cell types express single or multiple isoforms at different levels, suggesting that alternative splicing could determine the isoform types and their levels depending on cell (or tissue) type. The larval CNS displays distinct patterns of two isoforms, BaboA and BaboC. BaboC is mostly expressed in neural cells originating during embryogenesis, while BaboA is broadly expressed in neural cells produced from both embryonic and postembryonic stages. Assays of both isoform-specific mutants and cell-specific knockdown of individual isoforms revealed broad roles played by BaboA in postembryonic neurogenesis and differentiation of precursor neurons, remodeling processes of persisting larval neurons, and metamorphic CNS reorganization, which are essential for establishing of the adult CNS. Taken together, this study demonstrates that the GFP-tagged lines permit visualization of endogenous expression of individual isoforms, which further provides clues about cell- and stage-specific functions played by each isoform.

developmental biology↗

bioRxiv2024

Multiple Isoforms of the Activin-like receptor Baboon differentially regulate proliferation and conversion behaviors of neuroblasts and neuroepithelial cells in the Drosophila larval brain

In Drosophila coordinated proliferation of two neural stem cells, neuroblasts (NB) and neuroepithelial (NE) cells, is pivotal for proper larval brain growth that ultimately determines the final size and performance of an adult brain. The larval brain growth displays two phases based on behaviors of NB and NEs: the first one in early larval stages, influenced by nutritional status and the second one in the last larval stage, promoted by ecdysone signaling after critical weight checkpoint. Mutations of the baboon (babo) gene that produces three isoforms (BaboA-C), all acting as type-I receptors of Activin-type transforming growth factor {beta} (TGF-{beta}) signaling, cause a small brain phenotype due to severely reduced proliferation of the neural stem cells. In this study we show that loss of babo function severely affects proliferation of NBs and NEs as well as conversion of NEs from both phases. By analyzing babo-null and newly generated isoform-specific mutants by CRISPR mutagenesis as well as isoform-specific RNAi knockdowns in a cell- and stage-specific manner, we further demonstrate differential contributions of the isoforms for these cellular events with BaboA playing the major role. Our data show that stage-specific expression of EcR-B1 in the brain is also regulated primarily by BaboA along with function of the other isoforms. Blocking EcR function in both neural stem cells results in a small brain phenotype that is more severe than baboA-knockdown alone. In summary, our study proposes that the Babo-mediated signaling promotes proper behaviors of the neural stem cells in both phases and achieves this by acting upstream of EcR-B1 expression in the second phase. Author SummaryEvolutionarily conserved TGF-{beta} signaling pathway is widely utilized as a regulator of diverse processes of brain development in both vertebrates and invertebrates. A key element in Drosophila Activin type TGF-{beta} signaling pathway is the type-I receptor Babo. The babo gene produces three isoforms, each with a unique ligand preference. Our study uncovers that Babo-mediated signaling promotes proper proliferation of NBs and NEs and conversion of NEs, together responsible for the magnitude of larval brain size growth. Three isoforms act individually or together to regulate these cellular events in coordination with developmental status. Our findings emphasize that Babo-mediated signaling is a crucial regulator of postembryonic neurogenesis that generates 90% of neuronal population for the adult brain.

developmental biology↗

bioRxiv2021

The NDNF-like factor Nord is a Hedgehog-induced extracellular BMP modulator that regulates Drosophila wing patterning and growth

Hedgehog (Hh) and bone morphogenetic proteins (BMPs) pattern the developing Drosophila wing by functioning as short- and long-range morphogens, respectively. Here, we show that a previously unknown Hh-dependent mechanism fine-tunes the activity of BMPs. Through genome-wide expression profiling of the Drosophila wing imaginal discs, we identify nord as a novel target gene of the Hh signaling pathway. Nord is related to the vertebrate Neuron Derived Neurotrophic Factor (NDNF) involved in Congenital Hypogonadotropic Hypogonadism and several types of cancer. Loss- and gain-of-function analyses implicate Nord in the regulation of wing growth and proper crossvein patterning. At the molecular level, we present biochemical evidence that Nord is a secreted BMP-binding protein and localizes to the extracellular matrix. Nord binds to Decapentaplegic (Dpp) or the heterodimer Dpp-Glass bottom boat (Gbb) to modulate their release and activity. Furthermore, we demonstrate that Nord is a dosage-depend biphasic BMP modulator, where low levels of Nord promote and high levels inhibit BMP signaling. Taken together, we propose that Hh-induced Nord expression fine tunes both the range and strength of BMP signaling in the developing Drosophila wing. One sentence summaryThe NDNF-like factor Nord is a Hedgehog-induced and extracellular-localized biphasic BMP modulator that regulates Drosophila wing patterning and growth

developmental biology↗

bioRxiv2020

A novel juxtamembrane basolateral targeting motif regulates TGF-β receptor signaling in Drosophila

In polarized epithelial cells, receptor-ligand interactions can be restricted by different spatial distributions of the two interacting components, giving rise to an underappreciated layer of regulatory complexity. We explored whether such regulation occurs in the Drosophila wing disc, an epithelial tissue that requires the TGF-{beta} family member Dpp for growth and patterning. Dpp protein has been observed in a gradient within the columnar cells of the disc, but also uniformly in the disc lumen, leading to the question of how graded signaling is achieved in the face of two distinctly localized pools. We find the Dpp type II receptor Punt, but not the type I receptor Tkv, is enriched at the basolateral membrane, and depleted at the junctions and apical surface. Wit, a second type II receptor, shows a markedly different behavior, with the protein detected on all membrane regions but enriched at the apical side. Mutational studies identified the BLT, a short juxtamembrane sequence required for basolateral targeting of Punt in both wing discs and mammalian MDCK cells, and that dominantly confers basolateral localization on an otherwise apical receptor. Rescue of punt mutants with transgenes altered in the targeting motif showed that flies expressing apicalized Punt due to the lack of a functional BLT displayed developmental defects, female sterility and significant lethality. We also show that apicalized Punt does not produce an ectopic signal, indicating that the apical pool of Dpp is not a significant signaling source even when presented with Punt. Finally, we present evidence that the BLT acts through polarized sorting machinery that differs between types of epithelia. This suggests a code whereby each epithelial cell type may differentially traffic common receptors to enable distinctive responses to spatially localized pools of extracellular ligands.

cell biology↗

bioRxiv2020

Characterization of essential eggshell proteins from Aedes aegypti mosquitoes

Up to 40% of the world population now live in areas where dengue mosquito vectors coexist with humans. Aedes aegypti are vectors for zoonotic diseases that affect hundreds of millions of individuals per year globally. We recently identified the eggshell organizing factor 1 (EOF1) protein using systematic RNA interference (RNAi) screening of mosquito lineage-specific genes. It was shown that eggs deposited by RNAi-EOF1 A. aegypti and A. albopictus mosquitoes were non-melanized, fragile, and contained nonviable embryos. Motivated by this discovery, we performed RNAi screening of eggshell proteins to determine putative downstream target proteins of intracellular EOF1. We identified several eggshell proteins as essential for eggshell formation in A. aegypti and characterized their phenotypes in detail by molecular and biochemical approaches. We found that Nasrat, Closca, and Polehole structural proteins, together with the Nudel serine protease, are indispensable for eggshell melanization and egg viability. While all four proteins are predominantly expressed in ovaries of adult females, Nudel mRNA expression is highly upregulated in response to blood feeding. Furthermore, we identified four secreted eggshell enzymes as important factors for controlling the processes of mosquito eggshell formation and melanization. These enzymes included three dopachrome converting enzymes and one cysteine protease. All eight characterized eggshell proteins were required for intact eggshell formation. However, their surface topologies in response to RNAi did not phenocopy the effect of RNAi-EOF1. Still, it remains unclear how EOF1 influences eggshell formation and melanization. The use of proteomic analysis of eggshell proteins from RNAi-EOF1 assisted in the identification of additional proteins that could be regulated in EOF1 deficient eggshells.

developmental biology↗

bioRxiv2020

Engineering multiple species-like genetic incompatibilities in insects

Speciation constrains the flow of genetic information between populations of sexually reproducing organisms. Gaining control over mechanisms of speciation would enable new strategies to manage wild populations of disease vectors, agricultural pests, and invasive species. Additionally, such control would provide safe biocontainment of transgenes and gene drives. Natural speciation can be driven by pre-zygotic barriers that prevent fertilization or by post-zygotic genetic incompatibilities that render the hybrid progeny inviable or sterile. Here we demonstrate a general approach to create engineered genetic incompatibilities (EGIs) in the model insect Drosophila melanogaster. Our system couples a dominant lethal transgene with a recessive resistance allele. EGI strains that are homozygous for both elements are fertile and fecund when they mate with similarly engineered strains, but incompatible with wild-type strains that lack resistant alleles. We show that EGI genotypes can be tuned to cause hybrid lethality at different developmental life-stages. Further, we demonstrate that multiple orthogonal EGI strains of D. melanogaster can be engineered to be mutually incompatible with wild-type and with each other. Our approach to create EGI organisms is simple, robust, and functional in multiple sexually reproducing organisms.

synthetic biology↗

bioRxiv2019

Muscle-derived Myoglianin regulates Drosophila melanogaster imaginal disc growth

Organ growth and size are finely tuned by intrinsic and extrinsic signaling molecules. In Drosophila, the BMP family member Dpp is produced in a limited set of imaginal disc cells and functions as a classic morphogen to regulate pattern and growth by diffusing throughout imaginal discs. However, the role of TGF{beta}/Activin-like ligands in disc growth control remains ill-defined. Here we demonstrate that Myoglianin (Myo), an Activin family member, and a close homolog of mammalian Myostatin (Mstn), is a muscle-derived extrinsic factor that uses canonical dSmad2 mediated signaling to regulate wing size. We propose that Myo is a myokine that helps mediate an allometric relationship between muscles and their associated appendages.

developmental biology↗