The generation of a diversity of photoreceptor (PR) subtypes with different spectral sensitivities is essential for color vision in animals. In the Drosophila eye, the Hippo pathway has been ...implicated in blue- and green-sensitive PR subtype fate specification. Specifically, Hippo pathway activation promotes green-sensitive PR fate at the expense of blue-sensitive PRs. Here, using a sensitized triple heterozygote-based genetic screening approach, we report the identification of the single Drosophila zonula occludens-1 (ZO-1) protein Polychaetoid (Pyd) as a new regulator of the Hippo pathway during the blue- and green-sensitive PR subtype binary fate choice. We demonstrate that Pyd acts upstream of the core components and the upstream regulator Pez in the Hippo pathway. Furthermore, We found that Pyd represses the activity of Su(dx), a E3 ligase that negatively regulates Pez and can physically interact with Pyd, during PR subtype fate specification. Together, our results identify a new mechanism underlying the Hippo signaling pathway in post-mitotic neuronal fate specification.
The Hippo tumor suppressor pathway plays many fundamental cell biological roles during animal development. Two central players in controlling Hippo-dependent gene expression are the TEAD ...transcription factor Scalloped (Sd) and its transcriptional co-activator Yorkie (Yki). Hippo signaling phosphorylates Yki, thereby blocking Yki-dependent transcriptional control. In post-mitotic Drosophila photoreceptors, a bistable negative feedback loop forms between the Hippo-dependent kinase Warts/Lats and Yki to lock in green vs blue-sensitive neuronal subtype choices, respectively. Previous experiments indicate that sd and yki mutants phenocopy each other's functions, both being required for promoting the expression of the blue photoreceptor fate determinant melted (melt) and the blue-sensitive opsin Rh5. Here, we demonstrate that Sd ensures the robustness of this neuronal fate decision via multiple antagonistic gene regulatory roles. In Hippo-positive (green) photoreceptors, Sd directly represses both melt and Rh5 gene expression through defined TEAD binding sites, a mechanism that is antagonized by Yki in Hippo-negative (blue) cells. Additionally, in blue photoreceptors, Sd is required to promote the translation of the Rh5 protein through a 3′UTR-dependent and microRNA-mediated process. Together, these studies reveal that Sd can drive context-dependent cell fate decisions through opposing transcriptional and post-transcriptional mechanisms.
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•Scalloped represses blue photoreceptor fate determinants at the transcriptional level.•Yorkie antagonizes Scalloped's inhibition of blue photoreceptor fate.•Scalloped post-transcriptionally promotes blue fate via a miRNA-mediated mechanism.•microRNA machinery ensures mutual exclusion of sensory receptor expression.
Signaling pathways are reused for multiple purposes in plant and animal development. The Hippo pathway in mammals and Drosophila coordinates proliferation and apoptosis via the coactivator and ...oncoprotein YAP/Yorkie (Yki), which is homeostatically regulated through negative feedback. In the Drosophila eye, cross-repression between the Hippo pathway kinase LATS/Warts (Wts) and growth regulator Melted generates mutually exclusive photoreceptor subtypes. Here, we show that this all-or-nothing neuronal differentiation results from Hippo pathway positive feedback: Yki both represses its negative regulator, warts, and promotes its positive regulator, melted. This postmitotic Hippo network behavior relies on a tissue-restricted transcription factor network-including a conserved Otx/Orthodenticle-Nrl/Traffic Jam feedforward module-that allows Warts-Yki-Melted to operate as a bistable switch. Altering feedback architecture provides an efficient mechanism to co-opt conserved signaling networks for diverse purposes in development and evolution.
Early childhood dental caries (ECC) is the most common chronic disease among children, especially among low socioeconomic populations. Streptococcus mutans is most frequently associated with ...initiation of ECC. Although many studies report children with multiple S. mutans strains (i.e., genotypes) have greater odds of developing ECC, studies investigating intraspecies interactions in dental caries are lacking. This study investigates the impact of intraspecies interactions on cariogenic and fitness traits of clinical S. mutans isolates using in vitro and in vivo approaches. Association analysis evaluated if presence of multiple S. mutans genotypes within the first year of colonization was associated with caries. Initially, clinical S. mutans isolates from 10 children were evaluated. S. mutans strains (G09 and G18, most prevalent) isolated from one child were used for subsequent analysis. Biofilm analysis was performed for single and mixed cultures to assess cariogenic traits, including biofilm biomass, intra-polysaccharide, pH, and glucan. Confocal laser scanning microscopy (CLSM) and time-lapse imaging were used to evaluate spatial and temporal biofilm dynamics, respectively. A Drosophila model was used to assess colonization in vivo. Results showed the mean biofilm pH was significantly lower in co-cultured biofilms versus monoculture. Doubling of S. mutans biofilms was observed by CLSM and in vivo colonization in Drosophila for co-cultured S. mutans. Individual strains occupied specific domains in co-culture and G09 contributed most to increased co-culture biofilm thickness and colonization in Drosophila. Biofilm formation and acid production displayed distinct signatures in time-lapsed experiments. This study illuminates that intraspecies interactions of S. mutans significantly impacts biofilm acidity, architecture, and colonization.IMPORTANCEThis study sheds light on the complex dynamics of a key contributor to early childhood dental caries (ECC) by exploring intraspecies interactions of different S. mutans strains and their impact on cariogenic traits. Utilizing clinical isolates from children with ECC, the research highlights significant differences in biofilm architecture and acid production in mixed versus single genotype cultures. The findings reveal that co-cultured S. mutans strains exhibit increased cell density and acidity, with individual strains occupying distinct domains. These insights, enhanced by use of time-lapsed confocal laser scanning microscopy and a Drosophila model, offer a deeper understanding of ECC pathogenesis and potential avenues for targeted interventions.
The fruit fly
has emerged as a valuable model for investigating human biology, including the role of the microbiome in health and disease. Historically, studies involving the infection of
with single ...microbial species have yielded critical insights into bacterial colonization and host innate immunity. However, recent evidence has underscored that multiple microbial species can interact in complex ways through physical connections, metabolic cross-feeding, or signaling exchanges, with significant implications for healthy homeostasis and the initiation, progression, and outcomes of disease. As a result, researchers have shifted their focus toward developing more robust and representative
models of co-infection to probe the intricacies of polymicrobial synergy and dysbiosis. This review provides a comprehensive overview of the pioneering work and recent advances in the field, highlighting the utility of
as an alternative model for studying the multifaceted microbial interactions that occur within the oral cavity and other body sites. We will discuss the factors and mechanisms that drive microbial community dynamics, as well as their impacts on host physiology and immune responses. Furthermore, this review will delve into the emerging evidence that connects oral microbes to systemic conditions in both health and disease. As our understanding of the microbiome continues to evolve,
offers a powerful and tractable model for unraveling the complex interplay between host and microbes including oral microbes, which has far-reaching implications for human health and the development of targeted therapeutic interventions.
How complex networks of activators and repressors lead to exquisitely specific cell-type determination during development is poorly understood. In the
Drosophila eye, expression patterns of ...Rhodopsins define at least eight functionally distinct though related subtypes of photoreceptors. Here, we describe a role for the transcription factor gene
defective proventriculus (
dve) as a critical node in the network regulating Rhodopsin expression.
dve is a shared component of two opposing, interlocked feedforward loops (FFLs). Orthodenticle and Dve interact in an incoherent FFL to repress Rhodopsin expression throughout the eye. In R7 and R8 photoreceptors, a coherent FFL relieves repression by Dve while activating Rhodopsin expression. Therefore, this network uses repression to restrict and combinatorial activation to induce cell-type-specific expression. Furthermore, Dve levels are finely tuned to yield cell-type- and region-specific repression or activation outcomes. This interlocked FFL motif may be a general mechanism to control terminal cell-fate specification.
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► Dve is a key transcription factor in the network regulating Rhodopsins in the fly eye ► Dve is a shared component of two opposing, interlocked feedforward loops (FFLs) ► An incoherent FFL represses expression of Rhodopsins in outer photoreceptors ► A coherent FFL relieves Dve repression and activates Rhodopsins in inner photoreceptors
A major question in development is how different specialized cell types arise from a common progenitor. In the adult Drosophila compound eye, color discrimination is achieved by UV-, blue- and ...green-sensitive photoreceptors (PRs). These different PR subsets arise from neuronal precursors called R7 and R8 cells. Recent studies have demonstrated that R7-based UV-sensitive PRs require the repression of R8-based blue/green-sensitive PR characteristics to properly develop. This repression is mediated by the transcription factor Prospero (Pros). Here, we report that Senseless (Sens), a Drosophila ortholog of the vertebrate Gfi1 transcription factor, plays an opposing role to Pros by both negatively regulating R7-based features and positively enforcing R8-based features during terminal differentiation. In addition, we demonstrate that Pros and Sens function together with the transcription factor Orthodenticle (Otd) to oppositely regulate R7 and R8 PR Rhodopsin gene expression in vitro. These data show that sens, previously shown to be essential for neuronal specification, also controls differentiation of specific neuronal subtypes in the retina. Interestingly, Pros has recently been shown to function as a tumor suppressor, whereas Gfi1 is a well-characterized oncogene. Thus, we propose that sens/pros antagonism is important for regulating many biological processes.
Purpose: To investigate the anti-proliferative potential of quinolinol-platinum (II) complex {QN-Pt (II)} in laryngeal cancer cells.Methods: The inhibitory potential of QN-Pt (II) on the ...proliferation of laryngeal cancer cells was determined using 2H-tetrazolium, 2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl bromide (MTT) and colony formation assays. Inhibition of cell migration was determined using wound-healing assay, while changes in LC3-II and p62 expressions were assessed by western blotting.Results: QN-Pt (II) inhibited the viability of TU212 and M4e laryngeal cancer cells in the concentration range of 2 to 10 μM (p < 0.05). Moreover, it suppressed the colony formation potential and migration of TU212 and M4e cells. The QN-Pt (II) treatment increased the proportion of TU212 and M4e cells in G1/G0 phase of the cell cycle, but decreased the cell proportion in S and G2/M phase (p < 0.05). Treatment with 10 μM QN-Pt (II) increased the expression of LC3-II, but downregulated P62 expression in TU212 and M4e cells. The expression of Yes-associated protein was inhibited in TU212 and M4e cells on treatment with QN-Pt (II). However, transfection of YAP-cDNA into TU212 and M4e cells reversed the inhibitory effect of QN-Pt (II) on cell proliferation (p < 0.05). Moreover, YAP-cDNA transfection suppressed LC3II expression, inhibited YAP phosphorylation and promoted P62 expression in QN-Pt (II)-treated TU212 and M4e cells (p < 0.05).Conclusion: QN-Pt (II) suppresses laryngeal cancer cell viability via arrest of cell cycle and activation of apoptosis. Moreover, QN-Pt (II) targets Yes-associated protein in laryngeal cancer cells. Thus, QN-Pt (II) is a potential therapeutic agent for laryngeal cancer.
Keywords: Laryngeal cancer, YAP-protein, Apoptosis, Phosphorylation, Therapeutic agent
Orthodenticle (Otd)-related transcription factors are essential for anterior patterning and brain morphogenesis from Cnidaria to Mammals, and genetically underlie several human retinal pathologies. ...Despite their key developmental functions, relatively little is known regarding the molecular basis of how these factors regulate downstream effectors in a cell- or tissue-specific manner. Many invertebrate and vertebrate species encode two to three Otd proteins, whereas Drosophila encodes a single Otd protein. In the fly retina, Otd controls rhabdomere morphogenesis of all photoreceptors and regulates distinct Rhodopsin-encoding genes in a photoreceptor subtype-specific manner. Here, we performed a structure–function analysis of Otd during Drosophila eye development using in vivo rescue experiments and in vitro transcriptional regulatory assays. Our findings indicate that Otd requires at least three distinct transcriptional regulatory domains to control photoreceptor-specific rhodopsin gene expression and photoreceptor morphogenesis. Our results also uncover a previously unknown role for Otd in preventing co-expression of sensory receptors in blue vs. green-sensitive R8 photoreceptors. Sequence analysis indicates that many of the transcriptional regulatory domains identified here are conserved in multiple Diptera Otd-related proteins. Thus, these studies provide a basis for identifying shared molecular pathways involved in a wide range of developmental processes.
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