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Expression of SRY-box transcription factor 17 (Sox17) in the endodermal region caudal to the hepatic diverticulum during late gastrulation is necessary for hepato-pancreato-biliary system formation. Analysis of an allelic series of promoter-proximal mutations near the transcription start site (TSS) 2 of Sox17 in mouse has revealed that gallbladder (GB) and extrahepatic bile duct (EHBD) development is exquisitely sensitive to Sox17 expression levels. Deletion of a SOX17-binding cis-regulatory element in the TSS2 promoter impairs GB and EHBD development by reducing outgrowth of the nascent biliary bud. These findings reveal the existence of a SOX17-dependent autoregulatory loop that drives Sox17 expression above a critical threshold concentration necessary for GB and EHBD development to occur, and that minor impairments in Sox17 gene expression are sufficient to impair the expression of SOX17-regulated genes in the nascent GB and EHBD system, impairing or preventing development., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2025. Published by The Company of Biologists.)

G6PC2 is predominantly expressed in pancreatic islet β-cells where it encodes a glucose-6-phosphatase catalytic subunit that modulates the sensitivity of insulin secretion to glucose by opposing the action of glucokinase, thereby regulating fasting blood glucose (FBG). Prior studies have shown that the G6pc2 promoter alone is unable to confer sustained islet-specific gene expression in mice, suggesting the existence of distal enhancers that regulate G6pc2 expression. Using information from both mice and humans and knowledge that single nucleotide polymorphisms (SNPs) both within and near G6PC2 are associated with variations in FBG in humans, we identified several putative enhancers 3' of G6pc2. One region, herein referred to as enhancer I, resides in the 25th intron of Abcb11 and binds multiple islet-enriched transcription factors. CRISPR-mediated deletion of enhancer I in C57BL/6 mice had selective effects on the expression of genes near the G6pc2 locus. In isolated islets, G6pc2 and Spc25 expression were reduced ∼50%, and Gm13613 expression was abolished, whereas Cers6 and nostrin expression were unaffected. This partial reduction in G6pc2 expression enhanced islet insulin secretion at basal glucose concentrations but did not affect FBG or glucose tolerance in vivo, consistent with the absence of a phenotype in G6pc2 heterozygous C57BL/6 mice., (© 2023 by the American Diabetes Association.)

Homeostasis in the intestinal epithelium is maintained by Lgr5-positive intestinal stem cells (ISCs) located at the base of the crypt. The function of ISCs is reduced upon aging which leads to a decline of regeneration of the intestinal epithelium. We report that aged intestinal crypts present with an elevated activity of the small RhoGTPase Cdc42. Elevation of Cdc42 activity in young animals by genetic means causes premature ISC aging, whereas pharmacological suppression of elevated Cdc42 activity restores organoid formation potential in vitro . Consistent with a critical role of elevated Cdc42 activity in aged ISCs for a reduced regenerative capacity of aged ISCs, suppression of Cdc42 activity in vivo improves crypt regeneration in aged mice. Thus, pharmacological reduction of Cdc42 activity can improve the regeneration of aged intestinal epithelium., Competing Interests: H.G and Y.Z are inventors on patent US20150297563A1, Rejuvenation of precursor cells, which comprises, among others, methods of rejuvenating intestinal tissue via inhibition of GTPases., (© 2021 The Authors.)

Nutrients affect adult stem cells through complex mechanisms involving multiple organs. Adipocytes are highly sensitive to diet and have key metabolic roles, and obesity increases the risk for many cancers. How diet-regulated adipocyte metabolic pathways influence normal stem cell lineages, however, remains unclear. Drosophila melanogaster has highly conserved adipocyte metabolism and a well-characterized female germline stem cell (GSC) lineage response to diet. Here, we conducted an isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis to identify diet-regulated adipocyte metabolic pathways that control the female GSC lineage. On a rich (relative to poor) diet, adipocyte Hexokinase-C and metabolic enzymes involved in pyruvate/acetyl-CoA production are upregulated, promoting a shift of glucose metabolism toward macromolecule biosynthesis. Adipocyte-specific knockdown shows that these enzymes support early GSC progeny survival. Further, enzymes catalyzing fatty acid oxidation and phosphatidylethanolamine synthesis in adipocytes promote GSC maintenance, whereas lipid and iron transport from adipocytes controls vitellogenesis and GSC number, respectively. These results show a functional relationship between specific metabolic pathways in adipocytes and distinct processes in the GSC lineage, suggesting the adipocyte metabolism-stem cell link as an important area of investigation in other stem cell systems., (Copyright © 2017 by the Genetics Society of America.)

Although intestinal homeostasis is maintained by intestinal stem cells (ISCs), regeneration is impaired upon aging. Here, we first uncover changes in intestinal architecture, cell number, and cell composition upon aging. Second, we identify a decline in the regenerative capacity of ISCs upon aging because of a decline in canonical Wnt signaling in ISCs. Changes in expression of Wnts are found in stem cells themselves and in their niche, including Paneth cells and mesenchyme. Third, reactivating canonical Wnt signaling enhances the function of both murine and human ISCs and, thus, ameliorates aging-associated phenotypes of ISCs in an organoid assay. Our data demonstrate a role for impaired Wnt signaling in physiological aging of ISCs and further identify potential therapeutic avenues to improve ISC regenerative potential upon aging., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Intestinal stem cells (ISCs) drive small intestinal epithelial homeostasis and regeneration. Mechanistic target of rapamycin (mTOR) regulates stem and progenitor cell metabolism and is frequently dysregulated in human disease, but its physiologic functions in the mammalian small intestinal epithelium remain poorly defined. We disrupted the genes mTOR, Rptor, Rictor, or both Rptor and Rictor in mouse ISCs, progenitors, and differentiated intestinal epithelial cells (IECs) using Villin-Cre. Mutant tissues and wild-type or heterozygous littermate controls were analyzed by histologic immunostaining, immunoblots, and proliferation assays. A total of 10 Gy irradiation was used to injure the intestinal epithelium and induce subsequent crypt regeneration. We report that mTOR supports absorptive enterocytes and secretory Paneth and goblet cell function while negatively regulating chromogranin A-positive enteroendocrine cell number. Through additional Rptor, Rictor, and Rptor/Rictor mutant mouse models, we identify mechanistic target of rapamycin complex 1 as the major IEC regulatory pathway, but mechanistic target of rapamycin complex 2 also contributes to ileal villus maintenance and goblet cell size. Homeostatic adult small intestinal crypt cell proliferation, survival, and canonical wingless-int (WNT) activity are not mTOR dependent, but Olfm4(+) ISC/progenitor population maintenance and crypt regeneration postinjury require mTOR. Overall, we conclude that mTOR regulates multiple IEC lineages and promotes stem and progenitor cell activity during intestinal epithelium repair postinjury., (© FASEB.)

Adipocytes have key endocrine roles, mediated in large part by secreted protein hormones termed adipokines. The adipokine adiponectin is well known for its role in sensitizing peripheral tissues to insulin, and several lines of evidence suggest that adiponectin might also modulate stem cells/precursors. It remains unclear, however, how adiponectin signaling controls stem cells and whether this role is secondary to its insulin-sensitizing effects or distinct. Drosophila adipocytes also function as an endocrine organ and, although no obvious adiponectin homolog has been identified, Drosophila AdipoR encodes a well-conserved homolog of mammalian adiponectin receptors. Here, we generate a null AdipoR allele and use clonal analysis to demonstrate an intrinsic requirement for AdipoR in germline stem cell (GSC) maintenance in the Drosophila ovary. AdipoR null GSCs are not fully responsive to bone morphogenetic protein ligands from the niche and have a slight reduction in E-cadherin levels at the GSC-niche junction. Conversely, germline-specific overexpression of AdipoR inhibits natural GSC loss, suggesting that reduction in adiponectin signaling might contribute to the normal decline in GSC numbers observed over time in wild-type females. Surprisingly, AdipoR is not required for insulin sensitization of the germline, leading us to speculate that insulin sensitization is a more recently acquired function than stem cell regulation in the evolutionary history of adiponectin signaling. Our findings establish Drosophila female GSCs as a new system for future studies addressing the molecular mechanisms whereby adiponectin receptor signaling modulates stem cell fate., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Little is known about the long-term effects of dietary energy density (ED) on weight gain., Objective: The objective was to assess the long-term relation between changes in dietary ED and age-related weight gain., Design: We conducted a prospective study of 50 026 women (x +/- SD age: 36.5 +/- 4.6 y) in the Nurses' Health Study II followed from 1991 to 1999. Dietary ED and body weight were ascertained in 1991, 1995, and 1999. Total dietary ED was calculated by dividing each subject's daily energy intake (kcal) by the reported weight (g) of all foods consumed., Results: Dietary ED was positively correlated with saturated fat (r = 0.16), trans fat (r = 0.15), and the glycemic index (r = 0.16), but was inversely correlated with vegetable protein (r = -0.30), vegetables (r = -0.27), and fruit (r = -0.17). ED was not significantly correlated with total fat intake as a percentage of energy (r = 0.08). Women who increased their dietary ED during follow-up the most (5th quintile) had a significantly greater multivariate-adjusted weight gain than did those who decreased their dietary ED (1st quintile) (8-y time period: 6.42 kg compared with 4.57 kg; P for trend < 0.001). However, the amount of weight change over time varied considerably according to the ED values of individual foods and beverages., Conclusion: A high dietary ED reflects a dietary pattern higher in saturated and trans fats and refined carbohydrates. Increases in dietary ED were associated with greater weight gain among middle-aged women during 8 y of follow-up. However, public health recommendations cannot be made simply on the basis of ED values of individual foods and beverages.

Macrophage CSF (M-CSF, CSF-1) and IL-4 are two cytokines known to have effects on mature monocytic phagocytes in vitro. In this report we show that M-CSF and IL-4 activate resident mouse peritoneal macrophages to ingest particles via their C3b and C3bi receptors, which are not capable of mediating ingestion in resting cells. IgG-mediated ingestion was also increased by IL-4 and M-CSF. IL-1, IL-2, TNF-alpha, and IFN-gamma were not able to stimulate C receptor-mediated ingestion. Stimulation by IL-4 and M-CSF is dependent upon high cell density and greater than 24-h exposure to the cytokine. Interestingly, antibody to IFN-alpha/beta and mAb to IFN-beta inhibited the enhanced ingestion caused by both M-CSF and IL-4. However, neither IFN-alpha nor IFN-beta alone stimulated C receptor-mediated ingestion. M-CSF did not affect the ligand-independent distribution of CR3 on the macrophage surface. We conclude that two apparently unrelated cytokines, M-CSF and IL-4, both enhance macrophage phagocytosis of C and IgG-coated targets via a common pathway in which autocrine stimulation with IFN-alpha/beta is necessary but not sufficient.

The late operon of bacteriophage lambda contains the genes encoding the morphogenetic proteins of the phage. These genes are transcribed equally from the single late promoter. Although the functional half-lives of the mRNA for the various genes of this operon vary less than 2-fold, their relative rates of expression have been shown to vary by nearly 1000-fold. This variation could result from differing rates of translation initiation, from overlapping upstream translation, or from differential elongation rates due to the presence of codons for which the corresponding tRNAs are rare. To distinguish between these possibilities, we have cloned sequences surrounding the initiator codons of several of these genes and measured their ability to drive synthesis of hybrid lambda-beta-galactosidase proteins. The rates of expression of the hybrid genes thus produced correlate very well with the natural rates of expression of the corresponding phage genes, suggesting that the rate of initiation of translation controls the relative expression rates of these genes.