Coactosin-like protein 1 regulates integrity and repair of model intestinal epithelial barriers via actin binding dependent and independent mechanisms.

The actin cytoskeleton regulates the integrity and repair of epithelial barriers by mediating the assembly of tight junctions (TJs), and adherens junctions (AJs), and driving epithelial wound healing. Actin filaments undergo a constant turnover guided by numerous actin-binding proteins, however, the roles of actin filament dynamics in regulating intestinal epithelial barrier integrity and repair remain poorly understood. Coactosin-like protein 1 (COTL1) is a member of the ADF/cofilin homology domain protein superfamily that binds and stabilizes actin filaments.

Cell surface CD55 traffics to the nucleus leading to cisplatin resistance and stemness by inducing PRC2 and H3K27 trimethylation on chromatin in ovarian cancer.

Background: Platinum resistance is the primary cause of poor survival in ovarian cancer (OC) patients. Targeted therapies and biomarkers of chemoresistance are critical for the treatment of OC patients. Our previous studies identified cell surface CD55, a member of the complement regulatory proteins, drives chemoresistance and maintenance of cancer stem cells (CSCs).

Retrotransposons in embryogenesis and neurodevelopment.

Retrotransposable elements (RTEs) are genetic elements that can replicate and insert new copies into different genomic locations. RTEs have long been identified as 'parasitic genes', as their mobilization can cause mutations, DNA damage, and inflammation. Interestingly, high levels of retrotransposon activation are observed in early embryogenesis and neurodevelopment, suggesting that RTEs may possess functional roles during these stages of development.

Condensin-mediated restriction of retrotransposable elements facilitates brain development in Drosophila melanogaster.

Neural stem and progenitor cell (NSPC) maintenance is essential for ensuring that organisms are born with proper brain volumes and head sizes. Microcephaly is a disorder in which babies are born with significantly smaller head sizes and cortical volumes. Mutations in subunits of the DNA organizing complex condensin have been identified in microcephaly patients.

Condensin I and condensin II proteins form a LINE-1 dependent super condensin complex and cooperate to repress LINE-1.

Condensin I and condensin II are multi-subunit complexes that are known for their individual roles in genome organization and preventing genomic instability. However, interactions between condensin I and condensin II subunits and cooperative roles for condensin I and condensin II, outside of their genome organizing functions, have not been reported. We previously discovered that condensin II cooperates with Gamma Interferon Activated Inhibitor of Translation (GAIT) proteins to associate with Long INterspersed Element-1 (LINE-1 or L1) RNA and repress L1 protein expression and the retrotransposition of engineered L1 retrotransposition in cultured human cells.

A myosin chaperone, UNC-45A, is a novel regulator of intestinal epithelial barrier integrity and repair.

The actomyosin cytoskeleton serves as a key regulator of the integrity and remodeling of epithelial barriers by controlling assembly and functions of intercellular junctions and cell-matrix adhesions. Although biochemical mechanisms that regulate the activity of non-muscle myosin II (NM-II) in epithelial cells have been extensively investigated, little is known about assembly of the contractile myosin structures at the epithelial adhesion sites. UNC-45A is a cytoskeletal chaperone that is essential for proper folding of NM-II heavy chains and myofilament assembly.

Integrated multiomics analysis identifies molecular landscape perturbations during hyperammonemia in skeletal muscle and myotubes.

Ammonia is a cytotoxic molecule generated during normal cellular functions. Dysregulated ammonia metabolism, which is evident in many chronic diseases such as liver cirrhosis, heart failure, and chronic obstructive pulmonary disease, initiates a hyperammonemic stress response in tissues including skeletal muscle and in myotubes. Perturbations in levels of specific regulatory molecules have been reported, but the global responses to hyperammonemia are unclear.

Functional genomics analysis of human colon organoids identifies key transcription factors.

Organoids are a valuable three-dimensional (3D) model to study the differentiated functions of the human intestinal epithelium. They are a particularly powerful tool to measure epithelial transport processes in health and disease. Though biological assays such as organoid swelling and intraluminal pH measurements are well established, their underlying functional genomics are not well characterized.

PACT-mediated PKR activation acts as a hyperosmotic stress intensity sensor weakening osmoadaptation and enhancing inflammation.

The inability of cells to adapt to increased environmental tonicity can lead to inflammatory gene expression and pathogenesis. The Rel family of transcription factors TonEBP and NF-κB p65 play critical roles in the switch from osmoadaptive homeostasis to inflammation, respectively. Here we identified PACT-mediated PKR kinase activation as a marker of the termination of adaptation and initiation of inflammation in embryonic fibroblasts.

Epigenetics, DNA Organization, and Inflammatory Bowel Disease.

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders affecting the gastrointestinal tract. The incidence of IBD is increasing, with more cases occurring in developed countries. Multiple factors such as genetics, environmental changes, gut microbiota, and immune abnormalities have been associated with development of IBD.

Condensin II and GAIT complexes cooperate to restrict LINE-1 retrotransposition in epithelial cells.

LINE-1 (L1) retrotransposons can mobilize (retrotranspose) within the human genome, and mutagenic de novo L1 insertions can lead to human diseases, including cancers. As a result, cells are actively engaged in preventing L1 retrotransposition. This work reveals that the human Condensin II complex restricts L1 retrotransposition in both non-transformed and transformed cell lines through inhibition of L1 transcription and translation.

Layilin is critical for mediating hyaluronan 35kDa-induced intestinal epithelial tight junction protein ZO-1 in vitro and in vivo.

Tight junction proteins are critical in maintaining homeostatic intestinal permeability. Multiple intestinal inflammatory diseases are correlated with reduced expression of tight junction proteins. We have recently reported that oral treatment of mice with Hyaluronan 35kDa (HA35) increases colonic expression of tight junction protein zonula occludens-1 (ZO-1).

Glioblastoma Cancer Stem Cells Evade Innate Immune Suppression of Self-Renewal through Reduced TLR4 Expression.

Tumors contain hostile inflammatory signals generated by aberrant proliferation, necrosis, and hypoxia. These signals are sensed and acted upon acutely by the Toll-like receptors (TLRs) to halt proliferation and activate an immune response. Despite the presence of TLR ligands within the microenvironment, tumors progress, and the mechanisms that permit this growth remain largely unknown.

Protein Kinase R Mediates the Inflammatory Response Induced by Hyperosmotic Stress.

High extracellular osmolarity results in a switch from an adaptive to an inflammatory gene expression program. We show that hyperosmotic stress activates the protein kinase R (PKR) independently of its RNA-binding domain. In turn, PKR stimulates nuclear accumulation of nuclear factor κB (NF-κB) p65 species phosphorylated at serine-536, which is paralleled by the induction of a subset of inflammatory NF-κB p65-responsive genes, including inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), and IL-1β.

Drosophila Condensin II subunit Chromosome-associated protein D3 regulates cell fate determination through non-cell-autonomous signaling.

The pattern of the Drosophila melanogaster adult wing is heavily influenced by the expression of proteins that dictate cell fate decisions between intervein and vein during development. dSRF (Blistered) expression in specific regions of the larval wing disc promotes intervein cell fate, whereas EGFR activity promotes vein cell fate. Here, we report that the chromatin-organizing protein CAP-D3 acts to dampen dSRF levels at the anterior/posterior boundary in the larval wing disc, promoting differentiation of cells into the anterior crossvein.

Crossing the LINE Toward Genomic Instability: LINE-1 Retrotransposition in Cancer.

Retrotransposons are repetitive DNA sequences that are positioned throughout the human genome. Retrotransposons are capable of copying themselves and mobilizing new copies to novel genomic locations in a process called retrotransposition. While most retrotransposon sequences in the human genome are incomplete and incapable of mobilization, the LINE-1 retrotransposon, which comprises~17% of the human genome, remains active.

Chromosome-associated protein D3 promotes bacterial clearance in human intestinal epithelial cells by repressing expression of amino acid transporters.

Background & Aims: Defects in colonic epithelial barrier defenses are associated with ulcerative colitis (UC). The proteins that regulate bacterial clearance in the colonic epithelium have not been completely identified. The Drosophila chromosome-associated protein D3 (dCAP-D3) regulates responses to bacterial infection.

Condensin II subunit dCAP-D3 restricts retrotransposon mobilization in Drosophila somatic cells.

Retrotransposon sequences are positioned throughout the genome of almost every eukaryote that has been sequenced. As mobilization of these elements can have detrimental effects on the transcriptional regulation and stability of an organism's genome, most organisms have evolved mechanisms to repress their movement. Here, we identify a novel role for the Drosophila melanogaster Condensin II subunit, dCAP-D3 in preventing the mobilization of retrotransposons located in somatic cell euchromatin.

On the role of PDZ domain-encoding genes in Drosophila border cell migration.

Cells often move as collective groups during normal embryonic development and wound healing, although the mechanisms governing this type of migration are poorly understood. The Drosophila melanogaster border cells migrate as a cluster during late oogenesis and serve as a powerful in vivo genetic model for collective cell migration. To discover new genes that participate in border cell migration, 64 out of 66 genes that encode PDZ domain-containing proteins were systematically targeted by in vivo RNAi knockdown.

Identification of E2F target genes that are rate limiting for dE2F1-dependent cell proliferation.

Background: Microarray studies have shown that the E2F transcription factor influences the expression of many genes but it is unclear how many of these targets are important for E2F-mediated control of cell proliferation.

Results: We assembled a collection of mutant alleles of 44 dE2F1-dependent genes and tested whether these could modify visible phenotypes caused by the tissue-specific depletion of dE2F1. More than half of the mutant alleles dominantly enhanced de2f1-dsRNA phenotypes suggesting that the in vivo functions of dE2F1 can be limited by the reduction in the level of expression of many different targets.