FoxA transcription factor Fork head maintains the intestinal stem/progenitor cell identities in Drosophila

A bHLH interaction code controls bipotential differentiation and self-renewal in the Drosophila gut

Multipotent adult stem cells balance self-renewal with differentiation into various cell types. How this balance is regulated at the transcriptional level is poorly understood. Here, we show that a network of basic helix-loop-helix (bHLH) transcription factors controls both stemness and bipotential differentiation in the Drosophila adult intestine. We find that homodimers of Daughterless (Da), a homolog of mammalian E proteins, maintain self-renewal of intestinal stem cells (ISCs), antagonizing the enteroendocrine fate promoted by heterodimers of Da and Scute (Sc; homolog of ASCL). The HLH factor Extramacrochaetae (Emc; homologous to Id proteins) promotes absorptive differentiation by titrating Da and Sc. Emc prevents the committed absorptive progenitor from dedifferentiating, underscoring the plasticity of these cells. Switching physical interaction partners in this way enables the active maintenance of stemness while priming stem cells for differentiation along two alternative fates. Such regulatory logic is likely operative in other bipotent stem cell systems.

The AaFoxA factor regulates female reproduction through chromatin remodeling in the mosquito vector Aedes aegypti

Female mosquitoes are vectors of many devastating human diseases because they require blood feeding to initiate reproduction. Thus, elucidation of molecular mechanisms managing female mosquito reproduction is essential. Although the regulation of gene expression during the mosquito gonadotrophic cycle has been studied in detail, how this process is controlled at the chromatin level remains unclear. Chromatin must be accessible for transcription factors (TFs) governing gene expression. A specialized class of TFs, called pioneer factors (PFs), binds and remodels closed chromatin, permitting other TFs to bind DNA and activate the gene expression. Here, we identified a homolog of the vertebrate PF FoxA in the mosquito Aedes aegypti and used the CRISPR-Cas9 system to generate mosquitoes deficient in AaFoxA. We found that ovary development was severely retarded in mutant females. Multiomics and molecular biology analyses have shown that AaFoxA increased histone acetylation and decreased methylation of H3K27 by controlling the chromatin accessibility of histone modification enzymes and chromatin remodelers. AaFoxA is bound to the loci of chromatin remodelers, changing their chromatin accessibility and modulating their temporal expression patterns. AaFoxA increased the accessibility of the ecdysone receptor (EcR) and E74 loci, indicating the important role of AaFoxA in the hormonal regulation of mosquito reproductive events. Further, the CUT&RUN and ATAC-seq analyses revealed that AaFoxA temporarily bound closed chromatin, making it differentially accessible during the mosquito gonadotrophic cycle. Hence, this study demonstrates that AaFoxA modulates chromatin dynamics throughout female mosquito reproduction.

Regulation of the Intestinal Stem Cell Pool and Proliferation in Drosophila

Understanding the regulation of somatic stem cells, both during homeostasis and in response to environmental challenges like injury, infection, chemical exposure, and nutritional changes, is critical because their dysregulation can result in tissue degeneration or tumorigenesis. The use of models such as the Drosophila and mammalian adult intestines offers valuable insights into tissue homeostasis and regeneration, advancing our knowledge of stem cell biology and cancer development. This review highlights significant findings from recent studies, unveiling the molecular mechanisms that govern self-renewal, proliferation, differentiation, and regeneration of intestinal stem cells (ISCs). These insights not only enhance our understanding of normal tissue maintenance but also provide critical perspectives on how ISC dysfunction can lead to pathological conditions such as colorectal cancer (CRC).

Cell type-specific modulation of healthspan by Forkhead family transcription factors in the nervous system

Reduced activity of insulin/insulin-like growth factor signaling (IIS) increases healthy lifespan among diverse animal species. Downstream of IIS, multiple evolutionarily conserved transcription factors (TFs) are required; however, distinct TFs are likely responsible for these effects in different tissues. Here we have asked which TFs can extend healthy lifespan within distinct cell types of the adult nervous system in Drosophila Starting from published single-cell transcriptomic data, we report that forkhead (FKH) is endogenously expressed in neurons, whereas forkhead-box-O (FOXO) is expressed in glial cells. Accordingly, we find that neuronal FKH and glial FOXO exert independent prolongevity effects. We have further explored the role of neuronal FKH in a model of Alzheimer's disease-associated neuronal dysfunction, where we find that increased neuronal FKH preserves behavioral function and reduces ubiquitinated protein aggregation. Finally, using transcriptomic profiling, we identify Atg17, a member of the Atg1 autophagy initiation family, as one FKH-dependent target whose neuronal overexpression is sufficient to extend healthy lifespan. Taken together, our results underscore the importance of cell type-specific mapping of TF activity to preserve healthy function with age.

The epigenetic regulator Mll1 is required for Wnt-driven intestinal tumorigenesis and cancer stemness

Wnt/β-catenin signaling is crucial for intestinal carcinogenesis and the maintenance of intestinal cancer stem cells. Here we identify the histone methyltransferase Mll1 as a regulator of Wnt-driven intestinal cancer. Mll1 is highly expressed in Lgr5⁺ stem cells and human colon carcinomas with increased nuclear β-catenin. High levels of MLL1 are associated with poor survival of colon cancer patients. The genetic ablation of Mll1 in mice prevents Wnt/β-catenin-driven adenoma formation from Lgr5⁺ intestinal stem cells. Ablation of Mll1 decreases the self-renewal of human colon cancer spheres and halts tumor growth of xenografts. Mll1 controls the expression of stem cell genes including the Wnt/β-catenin target gene Lgr5. Upon the loss of Mll1, histone methylation at the stem cell promoters switches from activating H3K4 tri-methylation to repressive H3K27 tri-methylation, indicating that Mll1 sustains stem cell gene expression by antagonizing gene silencing through polycomb repressive complex 2 (PRC2)-mediated H3K27 tri-methylation. Transcriptome profiling of Wnt-mutated intestinal tumor-initiating cells reveals that Mll1 regulates Gata4/6 transcription factors, known to sustain cancer stemness and to control goblet cell differentiation. Our results demonstrate that Mll1 is an essential epigenetic regulator of Wnt/β-catenin-induced intestinal tumorigenesis and cancer stemness.

Intestinal cancer stem cells (CSC) are associated with colon cancer. Here, the authors show that Wnt/beta-catenin signalling in CSC requires the epigenetic regulator Mll1 to promote stemness and tumourigenesis in murine and human colon cancer models.

Leishmania infection induces a limited differential gene expression in the sand fly midgut

BACKGROUND

Sand flies are the vectors of Leishmania parasites. To develop in the sand fly midgut, Leishmania multiplies and undergoes various stage differentiations giving rise to the infective form, the metacyclic promastigotes. To determine the changes in sand fly midgut gene expression caused by the presence of Leishmania, we performed RNA-Seq of uninfected and Leishmania infantum-infected Lutzomyia longipalpis midguts from seven different libraries corresponding to time points which cover the various Leishmania developmental stages.

RESULTS

The combined transcriptomes resulted in the de novo assembly of 13,841 sand fly midgut transcripts. Importantly, only 113 sand fly transcripts, about 1%, were differentially expressed in the presence of Leishmania parasites. Further, we observed distinct differentially expressed sand fly midgut transcripts corresponding to the presence of each of the various Leishmania stages suggesting that each parasite stage influences midgut gene expression in a specific manner. Two main patterns of sand fly gene expression modulation were noted. At early time points (days 1-4), more transcripts were down-regulated by Leishmania infection at large fold changes (> 32 fold). Among the down-regulated genes, the transcription factor Forkhead/HNF-3 and hormone degradation enzymes were differentially regulated on day 2 and appear to be the upstream regulators of nutrient transport, digestive enzymes, and peritrophic matrix proteins. Conversely, at later time points (days 6 onwards), most of the differentially expressed transcripts were up-regulated by Leishmania infection with small fold changes (< 32 fold). The molecular functions of these genes have been associated with the metabolism of lipids and detoxification of xenobiotics.

CONCLUSION

Overall, our data suggest that the presence of Leishmania produces a limited change in the midgut transcript expression profile in sand flies. Further, Leishmania modulates sand fly gene expression early on in the developmental cycle in order to overcome the barriers imposed by the midgut, yet it behaves like a commensal at later time points where a massive number of parasites in the anterior midgut results only in modest changes in midgut gene expression.

Sox100B Regulates Progenitor-Specific Gene Expression and Cell Differentiation in the Adult Drosophila Intestine

Robust production of terminally differentiated cells from self-renewing resident stem cells is essential to maintain proper tissue architecture and physiological functions, especially in high-turnover tissues. However, the transcriptional networks that precisely regulate cell transition and differentiation are poorly understood in most tissues. Here, we identified Sox100B, a Drosophila Sox E family transcription factor, as a critical regulator of adult intestinal stem cell differentiation. Sox100B is expressed in stem and progenitor cells and required for differentiation of enteroblast progenitors into absorptive enterocytes. Mechanistically, Sox100B regulates the expression of another critical stem cell differentiation factor, Sox21a. Supporting a direct control of Sox21a by Sox100B, we identified a Sox21a intronic enhancer that is active in all intestinal progenitors and directly regulated by Sox100B. Taken together, our results demonstrate that the activity and regulation of two Sox transcription factors are essential to coordinate stem cell differentiation and proliferation and maintain intestinal tissue homeostasis.

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Sox100B is expressed in progenitor cells in the adult intestine

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Sox100B is required for stem cell differentiation

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Sox100B is required for Sox21a expression

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Sox100B directly controls the activity of a Sox21a intronic enhancer

Identification and expression profiles of Fox transcription factors in the Yesso scallop (Patinopecten yessoensis)

The forkhead box (Fox) gene family is a family of transcription factors that play important roles in a variety of biological processes in vertebrates, including early development and cell proliferation and differentiation. However, at present, studies on the mollusk Fox family are relatively lacking. In the present study, the Fox gene family of the Yesso scallop (Patinopecten yessoensis) was systematically identified. In addition, the expression profiles of the Fox gene family in early development and adult tissues were analyzed. The results showed that there were 26 Fox genes in P. yessoensis. Of the 26 genes, 24 belonged to 20 subfamilies. The Fox genes belonging to the I, Q1, R and S subfamilies were absent in P. yessoensis. The other 2 genes formed 2 independent clades with the Fox genes of other mollusks and protostomes. They might be new members of the Fox family and were named FoxY and FoxZ. P. yessoensis contained a FoxC-FoxL1 gene cluster similar in structure to that of Branchiostoma floridae, suggesting that the cluster might already exist in the ancestors of bilaterally symmetrical animals. The gene expression analysis of Fox showed that most of the genes were continuously expressed in multiple stages of early development, suggesting that Fox genes might be widely involved in the regulation of embryo and larval development of P. yessoensis. Nine Fox genes were specifically expressed in certain tissues, such as the nerve ganglia, foot, ovary, testis, and gills. For the 9 genes that were differentially expressed between the testis and ovary, their expression levels were analyzed during the 4 developmental stages of gonads. The results showed that FoxL2, FoxE and FoxY were highly expressed in the ovary during all developmental stages, while FoxZ was highly expressed in the testis during all developmental stages. The results suggested that these genes might play an important role in sex maintenance or gametogenesis. The present study could provide a reference for evolutionary and functional studies of the Fox family in metazoans.

Signification of forkhead box A1 (FOXA1) expression in thyroid cancers

BACKGROUND

Forkhead box A1 (FOXA1) plays an important role in several tumors. This study investigated the potential role of FOXA1 expression in thyroid tumors. We conducted a retrospective study of 110 thyroid lesions and tumors diagnosed during 1995-2018. The expression of FOXA1 was analyzed by immunohistochemistry on archival material.

RESULTS

No FOXA1 immunostaining was observed in all cases of Graves' disease, Hashimoto's disease, multi-nodular goiter, and adenoma. FOXA1 expression was absent as well in all papillary and follicular carcinomas, Hurthle cell carcinoma, and undifferentiated sarcoma. Only three anaplastic carcinomas exhibited focally FOXA1 staining. However, FOXA1 was expressed in all medullary carcinomas. No significant correlation was found with all clinicopathological features (p > 0.05 for all). The pattern of FOXA1 staining was similar to that of calcitonin and chromogranin A (p = 0.04 and p = 0.003, respectively).

CONCLUSIONS

FOXA1 is expressed mostly in all medullary thyroid carcinomas. Hence, FOXA1 could serve as an additional marker for refining the diagnosis of medullary thyroid carcinoma.

Expression and prognosis analyses of forkhead box A (FOXA) family in human lung cancer

Despite advances in early diagnosis and treatment, cancer still remains the major reason of mortality worldwide. The forkhead box A (FOXA) family is reported to participate in diverse human diseases. However, little is known about their expression and prognostic values in human lung cancer. Herein, we conducted a detailed cancer vs. normal analysis. The mRNA expression levels of FOXA family in numerous kind of cancers, including lung cancer, were analyzed using the Oncomine and GEPIA database. We observed that the mRNA expression levels of FOXA1, and FOXA3 were all increased while FOXA2 were decreased in most cancers compared with normal tissues, especially in lung cancer. Moreover, the expression levels of FOXA1, and FOXA3 are also highly expressed, while FOXA2 were decreased in almost all cancer cell lines, particularly in lung cancer cell lines, analyzing by Cancer Cell Line Encyclopedia (CCLE) and EMBL-EBI databases. Furthermore, the LinkedOmics database was used to evaluate the prognostic values, indicating that higher expression of FOXA1, FOXA3 indicated a poor overall survival (OS), while increased FOXA2 revealed a better OS in lung cancer. To conclusion, FOXA family showed significant expression differences between cancer and normal tissues, especially lung cancer, and FOXA1, FOXA3 could be promising prognostic biomarkers for lung cancer.

A SoxB gene acts as an anterior gap gene and regulates posterior segment addition in a spider

Sox genes encode a set of highly conserved transcription factors that regulate many developmental processes. In insects, the SoxB gene Dichaete is the only Sox gene known to be involved in segmentation. To determine if similar mechanisms are used in other arthropods, we investigated the role of Sox genes during segmentation in the spider Parasteatoda tepidariorum. While Dichaete does not appear to be involved in spider segmentation, we found that the closely related Sox21b-1 gene acts as a gap gene during formation of anterior segments and is also part of the segmentation clock for development of the segment addition zone and sequential addition of opisthosomal segments. Thus, we have found that two different mechanisms of segmentation in a non-mandibulate arthropod are regulated by a SoxB gene. Our work provides new insights into the function of an important and conserved gene family, and the evolution of the regulation of segmentation in arthropods.

Markers and Methods to Study Adult Midgut Stem Cells

Stem cells have emerged as a promising cell source to heal, replace or regenerate tissue and organs damaged by aging, injury or diseases. The intestinal epithelium is the most rapidly renewing tissue in our body, which is maintained by intestinal stem cells (ISCs), located at the bottom of the crypts. ISCs continuously replace lost or injured intestinal epithelial cells in organisms ranging from Drosophila to humans. The adult Drosophila midgut provides an excellent in vivo model system to study ISC behavior during stress, regeneration, aging and infection. There are several signaling pathways/genes have been identified to regulate ISCs self-renewal and differentiation during normal and pathological conditions. A significant number of genetic tools and markers have been developed in the last one decade to study Drosophila ISCs behavior. Here, we describe some of the markers and methods used to study ISCs behavior in adult midgut of Drosophila.