Fibroblast growth factor receptor 2c signaling is required for intestinal cell differentiation in zebrafish

Transcriptomic and proteomic signatures of stemness and differentiation in the colon crypt

Intestinal stem cells are non-quiescent, dividing epithelial cells that rapidly differentiate into progenitor cells of the absorptive and secretory cell lineages. The kinetics of this process is rapid such that the epithelium is replaced weekly. To determine how the transcriptome and proteome keep pace with rapid differentiation, we developed a new cell sorting method to purify mouse colon epithelial cells. Here we show that alternative mRNA splicing and polyadenylation dominate changes in the transcriptome as stem cells differentiate into progenitors. In contrast, as progenitors differentiate into mature cell types, changes in mRNA levels dominate the transcriptome. RNA processing targets regulators of cell cycle, RNA, cell adhesion, SUMOylation, and Wnt and Notch signaling. Additionally, global proteome profiling detected >2,800 proteins and revealed RNA:protein patterns of abundance and correlation. Paired together, these data highlight new potentials for autocrine and feedback regulation and provide new insights into cell state transitions in the crypt.

Cellular and epigenetic drivers of stem cell ageing

Adult tissue stem cells have a pivotal role in tissue maintenance and regeneration throughout the lifespan of multicellular organisms. Loss of tissue homeostasis during post-reproductive lifespan is caused, at least in part, by a decline in stem cell function and is associated with an increased incidence of diseases. Hallmarks of ageing include the accumulation of molecular damage, failure of quality control systems, metabolic changes and alterations in epigenome stability. In this Review, we discuss recent evidence in support of a novel concept whereby cell-intrinsic damage that accumulates during ageing and cell-extrinsic changes in ageing stem cell niches and the blood result in modifications of the stem cell epigenome. These cumulative epigenetic alterations in stem cells might be the cause of the deregulation of developmental pathways seen during ageing. In turn, they could confer a selective advantage to mutant and epigenetically drifted stem cells with altered self-renewal and functions, which contribute to the development of ageing-associated organ dysfunction and disease.

Fibroblast Growth Factors in the Gastrointestinal Tract: Twists and Turns

Fibroblast growth factors (FGFs) are a family of conserved peptides that play an important role in the development, homeostasis, and repair processes of many organ systems, including the gastrointestinal tract. All four FGF receptors and several FGF ligands are present in the intestine. They play important roles in controlling cell proliferation, differentiation, epithelial cell restitution, and stem cell maintenance. Several FGFs have also been proven to be protective against gastrointestinal diseases such as inflammatory bowel diseases or to aid in regeneration after intestinal loss associated with short bowel syndrome. Herein, we review the multifaceted actions of canonical FGFs in intestinal development, homeostasis, and repair in rodents and humans. Developmental Dynamics 246:344-352, 2017. © 2016 Wiley Periodicals, Inc.

Overexpression of miR-595 and miR-1246 in the sera of patients with active forms of inflammatory bowel disease

BACKGROUND

MicroRNAs (miRNAs) are dysregulated in the inflammatory bowel diseases, Crohn's disease (CD) and ulcerative colitis (UC), which arise due to dysfunctional host-microbe interactions and impairment of the barrier function of the intestine. Here, we sought to determine whether circulating miRNAs are biomarkers of active colonic CD and UC and can provide insights into disease pathogenesis. Comparison was made with serum miRNAs in patients with rheumatoid arthritis (RA).

METHODS

Total serum RNA from patients with colonic CD, UC, and RA, and normal healthy adults was screened for disease-associated miRNAs by microarray analysis, with subsequent validation by quantitative reverse-transcription polymerase chain reaction. MiRNA targets were identified by luciferase reporter assays.

RESULTS

MiR-595 and miR-1246 were significantly upregulated in the sera of active colonic CD, UC, and RA patients, compared with healthy subjects; and in active colonic CD and UC compared with inactive disease. Luciferase reporter assays indicated that miR-595 inhibits the expression of neural cell adhesion molecule-1 and fibroblast growth factor receptor 2.

CONCLUSIONS

Serum miR-595 and miR-1246 are biomarkers of active CD, UC, and RA. These findings gain significance from reports that miR-595 impairs epithelial tight junctions, whereas miR-1246 indirectly activates the proinflammatory nuclear factor of activated T cells. miR-595 targets the cell adhesion molecule neural cell adhesion molecule-1, and fibroblast growth factor receptor 2, which plays a key role in the differentiation, protection, and repair of colonic epithelium, and maintenance of tight junctions. miR-595 and miR-1246 warrant testing as potential targets for therapeutic intervention in the treatment of inflammatory bowel disease.

Regional environmental pressure influences population differentiation in turbot (Scophthalmus maximus)

Unravelling the factors shaping the genetic structure of mobile marine species is challenging due to the high potential for gene flow. However, genetic inference can be greatly enhanced by increasing the genomic, geographical or environmental resolution of population genetic studies. Here, we investigated the population structure of turbot (Scophthalmus maximus) by screening 17 random and gene-linked markers in 999 individuals at 290 geographical locations throughout the northeast Atlantic Ocean. A seascape genetics approach with the inclusion of high-resolution oceanographical data was used to quantify the association of genetic variation with spatial, temporal and environmental parameters. Neutral loci identified three subgroups: an Atlantic group, a Baltic Sea group and one on the Irish Shelf. The inclusion of loci putatively under selection suggested an additional break in the North Sea, subdividing southern from northern Atlantic individuals. Environmental and spatial seascape variables correlated marginally with neutral genetic variation, but explained significant proportions (respectively, 8.7% and 10.3%) of adaptive genetic variation. Environmental variables associated with outlier allele frequencies included salinity, temperature, bottom shear stress, dissolved oxygen concentration and depth of the pycnocline. Furthermore, levels of explained adaptive genetic variation differed markedly between basins (3% vs. 12% in the North and Baltic Sea, respectively). We suggest that stable environmental selection pressure contributes to relatively strong local adaptation in the Baltic Sea. Our seascape genetic approach using a large number of sampling locations and associated oceanographical data proved useful for the identification of population units as the basis of management decisions.