THE COMPOSITION AND PHYLOGENETIC SIGNIFICANCE OF THE MOUGEOTIA (CHAROPHYCEAE) CELL WALL1

The two-layered, fibrillar cell wall of Mougeotia C. Agardh sp. consisted of 63.6% non-cellulosic carbohydrates and 13.4% cellulose. The orientation of cellulose microfibrils in the native cell wall agrees with the multinet growth hypothesis, which has been employed to explain the shift in microfibril orientation from transverse (inner wall) toward axial (outer wall). Monosaccharide analysis of isolated cell walls revealed the presence of ten sugars with glucose, xylose and galactose most abundant. Methylation analysis of the acid-modified, 1 N NaOH insoluble residue fraction showed that it was composed almost exclusively of 4-linked glucose, confirming the presence of cellulose. The major hemicellulosic carbohydrate was semi-purified by DEAE Sephacel (Cl^?) anion-exchange chromatography of the hot 1 N NaOH soluble fraction. This hemicellulose was a xylan consisting of a 4-xylosyl backbone and 2,4-xylosyl branch points. The major hot water soluble neutral polysaccharide was identified as a 3-linked galactan. Mougeotia cell wall composition is similar to that of (Charophyceae) and has homologies with vascular plant cell walls. Our observations support transtructural evidence which suggests that members of the Charophyceae represent the phylogenetic line that gave rise to vascular plants. Therefore, the primary cell walls of vascular plants many have evolved directly from structures typical of the filamentous green algal cell walls found in the Charophyceae.     

Transcriptional Cofactor TBLR1 Controls Lipid Mobilization in White Adipose Tissue

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Highlights? TBLR1 controls cAMP-dependent lipolysis in adipocytes ? Adipocyte-specific deletion of TBLR1 in mice impairs fasting-induced lipolysis ? Lack of TBLR1 in adipocytes aggravates diet-induced obesity and metabolic dysfunction ? TBLR1 mRNA levels in WAT are elevated under lipolytic conditions in mice and humans     

Iron Regulatory Proteins Control a Mucosal Block to Intestinal Iron Absorption

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Highlights? Disruption of intestinal IRP function constrains iron absorption in adult mice ? IRPs must limit mucosal ferritin for efficient iron absorption ? IRPs control ferroportin directly and DMT1 directly or through HIF2α ? IRPs define a set point for hepcidin-mediated regulation of iron absorption     

Identification of liver‐derived bone morphogenetic protein (BMP)‐9 as a potential new candidate for treatment of colorectal cancer

Colorectal cancer (CRC) is a high‐incidence malignancy worldwide which still needs better therapy options. Therefore, the aim of the present study was to investigate the responses of normal or malignant human intestinal epithelium to bone morphogenetic protein (BMP)‐9 and to find out whether the application of BMP‐9 to patients with CRC or the enhancement of its synthesis in the liver could be useful strategies for new therapy approaches. In silico analyses of CRC patient cohorts (TCGA database) revealed that high expression of the BMP‐target gene ID1, especially in combination with low expression of the BMP‐inhibitor noggin, is significantly associated with better patient survival. Organoid lines were generated from human biopsies of colon cancer (T‐Orgs) and corresponding non‐malignant areas (N‐Orgs) of three patients. The N‐Orgs represented tumours belonging to three different consensus molecular subtypes (CMS) of CRC. Overall, BMP‐9 stimulation of organoids promoted an enrichment of tumour‐suppressive gene expression signatures, whereas the stimulation with noggin had the opposite effects. Furthermore, treatment of organoids with BMP‐9 induced ID1 expression (independently of high noggin levels), while treatment with noggin reduced ID1.In summary, our data identify the ratio between ID1 and noggin as a new prognostic value for CRC patient outcome. We further show that by inducing ID1, BMP‐9 enhances this ratio, even in the presence of noggin. Thus, BMP‐9 is identified as a novel target for the development of improved anti‐cancer therapies of patients with CRC.     

A new in vitro bioassay for cyst formation by renal cells from an autosomal dominant rat model of polycystic kidney disease

Summary Autosomal dominant polycystic kidney disease (ADPKD) is one of the most frequent human inherited diseases. The main feature of the disease is the development of renal cysts, first occurring in the proximal tubules, and with time, dominating all segments of the nephron, leading to end-stage renal disease in 50% of the patients in their fifth decade of life. A therapy for polycystic kidney disease (PKD) has not yet been developed. Patients coming to end-stage ADPKD require long-term dialysis and/or transplantation. A suitable animal model to study ADPKD is the spontaneously mutated Han:SPRD (cy/ +) rat, but a method to cultivate Han:SPRD (cy/ +) derived renal cells which preserves their ability to form cyst-like structures in vitro has previously not been reported. Based on this well-characterized animal model, we developed a cell culture model of renal cyst formation in vitro. When renal cells of the Han:SPRD (cy/ +) rat were isolated and cultured under conditions that prevent cell-substratum adhesion, large amounts of cyst-like structures were formed de novo from Han:SPRD (cy/ +) derived renal cells, but only a few from control rat renal cells. In contrast, when cultivated on plastic as monolayer cultures, Han:SPRD (cy/ +)-derived and control rat-derived renal cells were indistinguishable and did not form cyst-like structures. Immunohistochemical characterization of the cyst-like structures suggests tubular epithelial origin of the cyst-forming cells. The amount of cysts formed from Han:SPRD (cy/ +)-derived renal cells grown in a stationary suspension culture is susceptible to modulation by different conditions. Human cyst fluid and epidermal growth factor both stimulated the formation of cysts from Han:SPRD (cy/ +)-derived renal cells whereas taxol inhibited cystogenesis. In contrast, neither human cyst fluid nor epidermal growth factor affected the amount of cysts formed by control rat renal cells. As the culture model reported here allows not only the distinction of PKD-derived tubular epithelium from its normal counterpart, but also the modulation of cyst formation especially by Han:SPRD (cy/ +)-derived renal cells, it might be a useful prescreening protocol for potential treatments for PKD and thus reduce the need for animal experiments. Both authors contributed equally to the work.     

microRNA‐379 couples glucocorticoid hormones to dysfunctional lipid homeostasis

In mammals, glucocorticoids (GCs) and their intracellular receptor, the glucocorticoid receptor (GR), represent critical checkpoints in the endocrine control of energy homeostasis. Indeed, aberrant GC action is linked to severe metabolic stress conditions as seen in Cushing's syndrome, GC therapy and certain components of the Metabolic Syndrome, including obesity and insulin resistance. Here, we identify the hepatic induction of the mammalian conserved microRNA (miR)‐379/410 genomic cluster as a key component of GC/GR‐driven metabolic dysfunction. Particularly, miR‐379 was up‐regulated in mouse models of hyperglucocorticoidemia and obesity as well as human liver in a GC/GR‐dependent manner. Hepatocyte‐specific silencing of miR‐379 substantially reduced circulating very‐low‐density lipoprotein (VLDL)‐associated triglyceride (TG) levels in healthy mice and normalized aberrant lipid profiles in metabolically challenged animals, mediated through miR‐379 effects on key receptors in hepatic TG re‐uptake. As hepatic miR‐379 levels were also correlated with GC and TG levels in human obese patients, the identification of a GC/GR‐controlled miRNA cluster not only defines a novel layer of hormone‐dependent metabolic control but also paves the way to alternative miRNA‐based therapeutic approaches in metabolic dysfunction.     

Comparative transcriptome profiling of amyloid precursor protein family members in the adult cortex

Background

SOX2 is a key gene implicated in maintaining the stemness of embryonic and adult stem cells. SOX2 appears to re-activate in several human cancers including glioblastoma multiforme (GBM), however, the detailed response program of SOX2 in GBM has not yet been defined.

Results

We show that knockdown of the SOX2 gene in LN229 GBM cells reduces cell proliferation and colony formation. We then comprehensively characterize the SOX2 response program by an integrated analysis using several advanced genomic technologies including ChIP-seq, microarray profiling, and microRNA sequencing. Using ChIP-seq technology, we identified 4883 SOX2 binding regions in the GBM cancer genome. SOX2 binding regions contain the consensus sequence wwTGnwTw that occurred 3931 instances in 2312 SOX2 binding regions. Microarray analysis identified 489 genes whose expression altered in response to SOX2 knockdown. Interesting findings include that SOX2 regulates the expression of SOX family proteins SOX1 and SOX18, and that SOX2 down regulates BEX1 (brain expressed X-linked 1) and BEX2 (brain expressed X-linked 2), two genes with tumor suppressor activity in GBM. Using next generation sequencing, we identified 105 precursor microRNAs (corresponding to 95 mature miRNAs) regulated by SOX2, including down regulation of miR-143, -145, -253-5p and miR-452. We also show that miR-145 and SOX2 form a double negative feedback loop in GBM cells, potentially creating a bistable system in GBM cells.

Conclusions

We present an integrated dataset of ChIP-seq, expression microarrays and microRNA sequencing representing the SOX2 response program in LN229 GBM cells. The insights gained from our integrated analysis further our understanding of the potential actions of SOX2 in carcinogenesis and serves as a useful resource for the research community.     

Taxonomic significance of cellulosic cell walls in the bangiales (Rhodophyta)

Cellulose has been characterized from isolated cell walls of the conchocelis phases of both Porphyra umbilicalis and P. leucostricta. Evidence for cellulose II (regenerated cellulose) in Schweitzer's reagent extracts was provided by X-ray powder analysis and paper chromatography of partial hydrolyzates. The presence of cellulose in the conchocelis phase of species of Porphyra provides evidence for the continuity of cell wall composition within the Rhodophyta. Adoption of a classification scheme incorporating consolidation of all red algal orders under the single class Rhodophyceae is proposed.     

COMPOSITION OF EXTRACELLULAR POLYMERIC SUBSTANCES FROM PERIPHYTON ASSEMBLAGES IN THE FLORIDA EVERGLADES1

In wetland habitats, periphyton is a common component of open‐water areas with species assemblage determined by local water quality. Extracellular polymeric substances (EPS) secreted by algae and bacteria give structure to periphyton, and differences in EPS chemistry affect the functional roles of these polymers. The Florida Everglades provide a unique opportunity to study compositional differences of EPS from distinctive algal assemblages that characterize areas of differing water chemistry. Water conservation area (WCA)‐1 is a soft‐water impoundment; periphyton was loosely associated with Utricularia stems and amorphous in structure, with a diverse desmid and diatom assemblage, and varying cyanobacterial abundance. Extracellular polymers were abundant and were loosely cell‐associated sheaths and slime layers in addition to tightly cell‐associated capsules. The EPS were complex heteropolysaccharides with significant saccharide residues of glucose, xylose, arabinose, and fucose. Carboxylic acids were also prominent, while ester sulfates and proteins were small components. Structured, cohesive cyanobacteria‐dominated periphyton was observed in WCA‐2A, a minerotrophic impoundment, and filaments were heavily encrusted with calcium carbonate and detrital matter. EPS were primarily cell‐associated sheaths, and polymer residues were dominated by glucose, xylose, fucose, and galactose, with uronic acids also a significant component of the polymers. Principal components analysis revealed that periphyton community assemblage determined the monosaccharide composition of EPS, which ultimately determines a range of biogeochemical processes within the periphyton.