Development Of Adult Tissues Research Articles

Genome-wide analysis of the chromatin sites targeted by HEX 70a storage protein in the honeybee brain and fat body.

Hexamerins, the proteins massively stored in the larval haemolymph of insects, are gradually used throughout metamorphosis as a source of raw material and energy for the development of adult tissues. Such behaviour defined hexamerins as storage proteins. Immunofluorescence experiments coupled with confocal microscopy show a hexamerin, HEX 70a, in the nucleus of the brain and fat body cells from honeybee workers, an unexpected localization for a storage protein. HEX 70a colocalizes with fibrillarin, a nucleolar-specific protein and H3 histone, thus suggesting a potential role as a chromatin-binding protein. This was investigated through chromatin immunoprecipitation and high-throughput DNA sequencing (ChIP-seq). The significant HEX 70a-DNA binding sites were mainly localized at the intergenic, promoter and intronic regions. HEX 70a targeted DNA stretches mapped to the genomic regions encompassing genes with relevant functional attributes. Several HEX 70a targeted genes were associated with H3K27ac or/and H3K27me3, known as active and repressive histone marks. Brain and fat body tissues shared a fraction of the HEX 70 targeted genes, and tissue-specific targets were also detected. The presence of overrepresented DNA motifs in the binding sites is consistent with specific HEX 70a-chromatin association. In addition, a search for HEX 70a targets in RNA-seq public libraries of fat bodies from nurses and foragers revealed differentially expressed targets displaying hex 70a-correlated developmental expression, thus supporting a regulatory activity for HEX 70a. Our results support the premise that HEX 70a is a moonlighting protein that binds chromatin and has roles in the brain and fat body cell nuclei, apart from its canonical role as a storage protein.

IN VIVO ACTIVATION OF P2Y4 PURINERGIC RECEPTORS USING ATP IN RAT EPIDERMAL TISSUE.

The aim: This study was carried out to examine the presence of P2Y4 receptors in rat epidermal tissue and how their in vivo activation leads to histological and genetic changes. Materials and methods: Thirty-six Wistar rats were separated into six groups each of six rats, the control group and five injected groups with increasing concentrations of ATP intradermally (0.1, 5.0, 10.0, 50.0, 100.0 μg/ml). The histological and genetic examination was performed from excised tissues. Results: Noticeable histological thickening of the epidermal layer in rats injected with high concentrations of ATP. No apparent histological damage was seen in all injected groups. The genetic expression seems to also increase following exposure to variable concentrations of ATP. Conclusions: Purinergic receptors activated by ATP molecules are highly involved in the development of adult tissues. Their precise location within the epidermal layer indicated their importance in cellular proliferation and differentiation of epidermal cells. Excessive exposure to ATP results in their robust genetic ectopic over expression indicative of increased cellular activity.

Insulin-like growth factor (IGF)-like peptide and 20-hydroxyecdysone regulate the growth and development of the male genital disk through different mechanisms in the silkmoth, Bombyx mori

It is well established that ecdysteroids play pivotal roles in the regulation of insect molting and metamorphosis. However, the mechanisms by which ecdysteroids regulate the growth and development of adult organs after pupation are poorly understood. Recently, we have identified insulin-like growth factor (IGF)-like peptides (IGFLPs), which are secreted after pupation under the control of 20-hydroxyecdysone (20E). In the silkmoth, Bombyx mori, massive amounts of Bombyx-IGFLP (BIGFLP) are present in the hemolymph during pupal-adult development, suggesting its importance in the regulation of adult tissue growth. Thus, we hypothesized that the growth and development of adult tissues including imaginal disks are regulated by the combined effects of BIGFLP and 20E. In this study, we investigated the growth-promoting effects of BIGFLP and 20E using the male genital disks of B. mori cultured ex vivo, and further analyzed the cell signaling pathways mediating hormone actions. We demonstrate that 20E induces the elongation of genital disks, that both hormones stimulate protein synthesis in an additive manner, and that BIGFLP and 20E exert their effects through the insulin/IGF signaling pathway and mitogen-activated protein kinase pathway, respectively. These results show that the growth and development of the genital disk are coordinately regulated by both BIGFLP and 20E.

Abstract 2874: Genetic suppression reveals DNA repair-independent antagonism between BRCA1 and COBRA1 in mammary gland development

Abstract Breast cancer susceptibility gene BRCA1 is well known for its function in double strand break (DSB) DNA repair. While BRCA1 is also implicated in transcriptional regulation, the physiological significance remains unclear. Cofactor of BRCA1 (COBRA1) is a BRCA1-binding protein and an important regulator of transcription elongation. Here we used mouse genetics to interrogate functional interaction between BRCA1 and COBRA1 during mammary gland development. Tissue-specific deletion of Cobra1 reduced mammary epithelial compartments and blocked ductal morphogenesis, alveologenesis, and lactogenesis, demonstrating a pivotal role of COBRA1 in adult tissue development. Remarkably, these developmental deficiencies due to Cobra1 knockout were largely rescued by additional loss of full-length Brca1. Furthermore, Brca1/Cobra1 double knockout restored developmental transcription at puberty, altered luminal epithelial homeostasis, yet remained deficient in homologous recombination-based DSB repair. Thus our genetic suppression analysis uncovers a previously unappreciated, DNA repair-independent function of BRCA1 in antagonizing COBRA1-dependent transcription program during mammary gland development. Citation Format: Xiaowen Zhang, Sreejith J. Nair, Huai-Chin Chiang, Yao Wang, Md Jamiul Jahid, Jianhua Ruan, Victor X. Jin, Yanfen Hu, Rong Li. Genetic suppression reveals DNA repair-independent antagonism between BRCA1 and COBRA1 in mammary gland development. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2874.

Genetic suppression reveals DNA repair-independent antagonism between BRCA1 and COBRA1 in mammary gland development.

The breast cancer susceptibility gene BRCA1 is well known for its function in double-strand break (DSB) DNA repair. While BRCA1 is also implicated in transcriptional regulation, the physiological significance remains unclear. COBRA1 (also known as NELF-B) is a BRCA1-binding protein that regulates RNA polymerase II (RNAPII) pausing and transcription elongation. Here we interrogate functional interaction between BRCA1 and COBRA1 during mouse mammary gland development. Tissue-specific deletion of Cobra1 reduces mammary epithelial compartments and blocks ductal morphogenesis, alveologenesis and lactogenesis, demonstrating a pivotal role of COBRA1 in adult tissue development. Remarkably, these developmental deficiencies due to Cobra1 knockout are largely rescued by additional loss of full-length Brca1. Furthermore, Brca1/Cobra1 double knockout restores developmental transcription at puberty, alters luminal epithelial homoeostasis, yet remains deficient in homologous recombination-based DSB repair. Thus our genetic suppression analysis uncovers a previously unappreciated, DNA repair-independent function of BRCA1 in antagonizing COBRA1-dependent transcription programme during mammary gland development.

NKD1 marks intestinal and liver tumors linked to aberrant Wnt signaling

The activity of the Wnt pathway undergoes complex regulation to ensure proper functioning of this principal signaling mechanism during development of adult tissues. The regulation may occur at several levels and includes both positive and negative feedback loops. In the present study we employed one of such negative feedback regulators, naked cuticle homolog 1 (Nkd1), to follow the Wnt pathway activity in the intestine and liver and in neoplasia originated in these organs. Using lineage tracing in transgenic mice we localized Nkd1 mRNA to the bottom parts of the small intestinal crypts and hepatocytes surrounding the central vein of the hepatic lobule. Furthermore, in two mouse models of intestinal tumorigenesis, Nkd1 expression levels were elevated in tumors when compared to healthy tissue. We utilized a collection of human intestinal polyps and carcinomas to confirm that NKD1 represents a robust marker of neoplastic growth. In addition, expression analysis of NKD1 in liver cancer showed that high expression levels of the gene distinguish a subclass of hepatocellular carcinomas related to aberrant Wnt signaling. Finally, our results were confirmed by bioinformatic analysis of large publicly available datasets that included gene expression profiling and high-throughput sequencing data of human colon and liver cancer specimens.

Ectodomain shedding and ADAMs in development

Proteolytic enzymes belonging to the A Disintegin And Metalloproteinase (ADAM) family are able to cleave transmembrane proteins close to the cell surface, in a process referred to as ectodomain shedding. Substrates for ADAMs include growth factors, cytokines, chemokines and adhesion molecules, and, as such, many ADAM proteins play crucial roles in cell-cell adhesion, extracellular and intracellular signaling, cell differentiation and cell proliferation. In this Review, we summarize the fascinating roles of ADAMs in embryonic and adult tissue development in both vertebrates and invertebrates.

The Role of Cellular Plasticity in Cancer Development

It has traditionally been accepted that, in the process of cellular differentiation, developmental options are progressively restricted until commitment to a specific fate is established and then only terminal differentiation along this lineage is possible. Although this is usually the case in normal physiological development, the latest experimental evidences indicate that the differentiated state of mature cells is not always as stable and durable as it was thought to be. In fact, recently, a hidden plasticity has been revealed in differentiated cells which allows them to deviate to other cell types that might be, functionally, very far away in other developmental pathways. This plasticity has biological significance since it is necessary for normal development to occur, but it also makes possible the emergence of aberrant lineages when interferences with the normal transcriptional and epigenetic mechanisms in charge of maintaining cellular identity do appear. Cancer is one of the possible outcomes of this aberrant reprogramming. The plasticity of the initial cell suffering the first oncogenic alteration plays an essential role in cancer development, since only if this cell possesses enough plasticity a tumoral reprogramming will be possible and a full-blown tumor will develop. Also, plasticity makes it possible for differentiated cells to acquire cancer stem cell properties in the presence of the appropriate oncogenic insults. In this review we discuss the role of cellular plasticity in the normal development of adult tissues and how cellular susceptibility to reprogramming plays an essential part in cancer development.

Preferential Adhesion Mediated by Hibris and Roughest Regulates Morphogenesis and Patterning in the Drosophila Eye

Cell adhesion is essential for morphogenesis; however, the mechanisms by which cell adhesion coordinates precisely regulated morphogenesis are poorly understood. Here we analyze the morphogenetic processes that organize the interommatidial precursor cells (IPCs) of the Drosophila pupal eye. We demonstrate that the Drosophila immunoglobulin superfamily members Hibris and Roughest are essential for IPC morphogenesis in the eye. The two loci are expressed in complementary cell types, and Hibris and Roughest proteins bind directly in vivo. Primary pigment cells employ Hibris to function as organizers in this process; IPCs minimize contacts with neighboring IPCs and utilize Roughest to maximize contacts with primaries. In addition, we provide evidence that interactions between Hibris and Roughest promote junction formation and that levels of Roughest in individual cells determine their capacity for competition. Our results demonstrate that preferential adhesion mediated by heterophilic interacting cell-adhesion molecules can create a precise pattern by minimizing surface free energy.

A Wingful of Wingless

The Wnt protein encoded by the Drosophila wingless gene has critical roles in pattern formation during embryonic development and also in later development of the adult appendages. In embryonic development, the wingless (Wg) signal promotes expression of the product of the naked cuticle gene, Nkd, which functions as an intracellular inhibitor of wingless (Wg) signaling, thus providing a critical negative feedback loop. Given that Nkd appears to have no effect during development of the adult tissues, Gerlitz and Basler screened for additional genes whose expression pattern was consistent with function as a feedback inhibitor for Wg signaling. They isolated a new gene they call wingful. The Wf protein is a secreted protein with sequence similarity to hydrolases, indicating that it might function extracellularly to cleave a signaling molecule. Loss of function of Wf enhanced Wg signaling, whereas gain of Wf function inhibited Wf signaling. But Wf acted on development of the adult tissues, not the embryonic ones responsive to Nkd. The authors note that the two inhibitors of Wg signaling appear beautifully adapted to their respective roles. In early development, where Wg signals at short range, the Nkd protein inhibits intracellular signals whereas in later development of adult tissues, where Wg signaling occurs over a longer range, the extracellular Wf inhibitor comes into play, presumably assuring just the right shape and range of the Wg morphogen gradient.O. Gerlitz, K. Basler, Wingful, an extracellular feedback inhibitor of wingless. Genes Dev. 16, 1055-1059 (2002).[Abstract][Full Text]

A Wingful of Wingless

The Wnt protein encoded by the Drosophila wingless gene has critical roles in pattern formation during embryonic development and also in later development of the adult appendages. In embryonic development, the wingless (Wg) signal promotes expression of the product of the naked cuticle gene, Nkd, which functions as an intracellular inhibitor of wingless (Wg) signaling, thus providing a critical negative feedback loop. Given that Nkd appears to have no effect during development of the adult tissues, Gerlitz and Basler screened for additional genes whose expression pattern was consistent with function as a feedback inhibitor for Wg signaling. They isolated a new gene they call wingful . The Wf protein is a secreted protein with sequence similarity to hydrolases, indicating that it might function extracellularly to cleave a signaling molecule. Loss of function of Wf enhanced Wg signaling, whereas gain of Wf function inhibited Wf signaling. But Wf acted on development of the adult tissues, not the embryonic ones responsive to Nkd. The authors note that the two inhibitors of Wg signaling appear beautifully adapted to their respective roles. In early development, where Wg signals at short range, the Nkd protein inhibits intracellular signals whereas in later development of adult tissues, where Wg signaling occurs over a longer range, the extracellular Wf inhibitor comes into play, presumably assuring just the right shape and range of the Wg morphogen gradient. O. Gerlitz, K. Basler, Wingful, an extracellular feedback inhibitor of wingless. Genes Dev. 16 , 1055-1059 (2002). [Abstract] [Full Text]

Repression of Wnt-5a impairs DDR1 phosphorylation and modifies adhesion and migration of mammary cells.

The Wnt-5a gene encodes a secreted protein that controls several normal processes during embryogenesis and development of adult tissues by as yet unknown mechanisms. Endogenous expression of Wnt-5a mRNA is known to occur in both mouse and human mammary cell lines. To investigate the biological role of Wnt-5a in the human mammary epithelial cell line HB2, we used an antisense approach to repress endogenous expression of Wnt-5a protein. We also generated a cell population that constitutively overexpresses this protein. We found that overexpression of Wnt-5a protein enhanced cell-to-collagen binding and abolished hepatocyte growth factor-stimulated migration of HB2 transfectants through collagen matrices. Conversely, repression of Wnt-5a protein led to cell scattering, impaired cell-collagen interaction and enhanced cell motility. As we were searching for modified collagen receptors in antisense cells, we discovered that the collagen-binding discoidin domain receptor 1 (DDR1) failed to undergo phosphorylation. In reciprocal experiments, phosphorylation of DDR1 was consistently enabled by expression of Wnt-5a-HA protein in non-Wnt-5a-producing MCF-7 breast cancer cells. Activation of the Wnt/beta-catenin signalling pathway did not influence or mimic the Wnt-5a-mediated effect on DDR1 phosphorylation. These data demonstrate that Wnt-5a protein participates in regulation of adhesion to and migration through collagen and is also a co-factor necessary for collagen-induced activation of DDR1 receptors in mammary epithelial cells.

Insect metamorphosis: out with the old, in with the new.

During insect metamorphosis, the steroid hormone ecdysone activates programmed cell death of larval tissues and the further development of adult tissues. Recent studies suggest that the E93 gene is both necessary and sufficient to target tissues for ecdysone-induced apoptosis.

The Drosophila Cyclin D-Cdk4 complex promotes cellular growth

Mammalian cyclin D-Cdk4 complexes have been characterized as growth factor-responsive cell cycle regulators. Their levels rise upon growth factor stimulation, and they can phosphorylate and thus neutralize Retinoblastoma (Rb) family proteins to promote an E2F-dependent transcriptional program and S-phase entry. Here we characterize the in vivo function of Drosophila Cyclin D (CycD). We find that Drosophila CycD-Cdk4 does not act as a direct G(1)/S-phase regulator, but instead promotes cellular growth (accumulation of mass). The cellular response to CycD-Cdk4-driven growth varied according to cell type. In undifferentiated proliferating wing imaginal cells, CycD-Cdk4 caused accelerated cell division (hyperplasia) without affecting cell cycle phasing or cell size. In endoreplicating salivary gland cells, CycD-Cdk4 caused excessive DNA replication and cell enlargement (hypertrophy). In differentiating eyes, CycD-Cdk4 caused cell enlargement (hypertrophy) in post-mitotic cells. Interaction tests with a Drosophila Rb homolog, RBF, indicate that CycD-Cdk4 can counteract the cell cycle suppressive effects of RBF, but that its growth promoting activity is mediated at least in part via other targets.

Thyroid hormone regulation of apoptotic tissue remodeling: Implications from molecular analysis of amphibian metamorphosis

Organogenesis and tissue remodeling are critical processes during postembryonic animal development. Anuran metamorphosis has for nearly a century served as an excellent model to study these processes in vertebrates. Frogs not only have essentially the same organs with the same functions as higher vertebrates such as humans, but also employ similar organogenic processes involving highly conserved genes. Development of frog organs takes place during metamorphosis, which is free of any maternal influences but absolutely dependent on the presence of thyroid hormone. Furthermore, this process can be easily manipulated both in intact tadpoles and in organ cultures by controlling the availability of thyroid hormone. These interesting properties have led to extensive morphological, cellular, and biochemical studies on amphibian metamorphosis. More recently, the cloning of thyroid hormone receptors and the demonstration that they are transcription factors have encouraged enormous interest in the molecular pathways controlling tissue remodeling induced by thyroid hormone during metamorphosis. This article summarizes some of the recent studies on the mechanisms of gene regulation by thyroid hormone receptors and isolation and functional characterization of genes induced by thyroid hormone during Xenopus metamorphosis. Particular focus is placed on the remodeling of the animal intestine, which involves both apoptosis (programmed cell death) of larval cells and de novo development of adult tissues, and the roles of thyroid hormone-induced genes that encode matrix metalloproteinases during this process.

Crooked legs encodes a family of zinc finger proteins required for leg morphogenesis and ecdysone-regulated gene expression during Drosophila metamorphosis.

Drosophila imaginal discs undergo extensive pattern formation during larval development, resulting in each cell acquiring a specific adult fate. The final manifestation of this pattern into adult structures is dependent on pulses of the steroid hormone ecdysone during metamorphosis, which trigger disc eversion, elongation and differentiation. We have defined genetic criteria that allow us to screen for ecdysone-inducible regulatory genes that are required for this transformation from patterned disc to adult structure. We describe here the first genetic locus isolated using these criteria: crooked legs (crol). crol mutants die during pupal development with defects in adult head eversion and leg morphogenesis. The crol gene is induced by ecdysone during the onset of metamorphosis and encodes at least three protein isoforms that contain 12-18 C2H2 zinc fingers. Consistent with this sequence motif, crol mutations have stage-specific effects on ecdysone-regulated gene expression. The EcR ecdysone receptor, and the BR-C, E74 and E75 early regulatory genes, are submaximally induced in crol mutants in response to the prepupal ecdysone pulse. These changes in gene activity are consistent with the crol lethal phenotypes and provide a basis for understanding the molecular mechanisms of crol action. The genetic criteria described here provide a new direction for identifying regulators of adult tissue development during insect metamorphosis.

Size Variation and the Distribution of Hemimetabolous Aquatic Insects: Two Thermal Equilibrium Hypotheses

Adult body size and fecundity of a number of hemimetabolous aquatic insects depend largely on thermal conditions during the larval period. Small adults and reduced fecundity result when temperatures are either warmed or cooled with respect to more optimal thermal conditions. Temperature apparently affects adult size by altering the larval growth rate and the timing and rate of adult tissue development for each larva. The data suggest a new interpretation for the geographic distribution of aquatic insects.