Iron photocatalysis via Brønsted acid-unlocked ligand-to-metal charge transfer.

Reforming sustainable 3d-metal-based visible light catalytic platforms for inert bulk chemical activation is highly desirable. Herein, we demonstrate the use of a Brønsted acid to unlock robust and practical iron ligand-to-metal charge transfer (LMCT) photocatalysis for the activation of multifarious inert haloalkylcarboxylates (CnXmCOO-, X = F or Cl) to produce CnXm radicals. This process enables the fluoro-polyhaloalkylation of non-activated alkenes by combining easily available Selectfluor as a fluorine source. Valuable alkyl fluorides including potential drug molecules can be easily obtained through this protocol. Mechanistic studies indicate that the real light-harvesting species may derive from the in situ-assembly of Fe3+, CnXmCOO-, H+, and acetonitrile solvent, in which the Brønsted acid indeed increases the efficiency of LMCT between the iron center and CnXmCOO- via hydrogen-bond interactions. We anticipate that this Brønsted acid-unlocked iron LMCT platform would be an intriguing sustainable option to execute the activation of inert compounds.

Insm1 regulates mTEC development and immune tolerance.

The expression of self-antigens in medullary thymic epithelial cells (mTECs) is essential for the establishment of immune tolerance, but the regulatory network that controls the generation and maintenance of the multitude of cell populations expressing self-antigens is poorly understood. Here, we show that Insm1, a zinc finger protein with known functions in neuroendocrine and neuronal cells, is broadly coexpressed with an autoimmune regulator (Aire) in mTECs. Insm1 expression is undetectable in most mimetic cell populations derived from mTECs but persists in neuroendocrine mimetic cells. Mutation of Insm1 in mice downregulated Aire expression, dysregulated the gene expression program of mTECs, and altered mTEC subpopulations and the expression of tissue-restricted antigens. Consistent with these findings, loss of Insm1 resulted in autoimmune responses in multiple peripheral tissues. We found that Insm1 regulates gene expression in mTECs by binding to chromatin. Interestingly, the majority of the Insm1 binding sites are co-occupied by Aire and enriched in superenhancer regions. Together, our data demonstrate the important role of Insm1 in the regulation of the repertoire of self-antigens needed to establish immune tolerance.

Prox2 and Runx3 vagal sensory neurons regulate esophageal motility.

Vagal sensory neurons monitor mechanical and chemical stimuli in the gastrointestinal tract. Major efforts are underway to assign physiological functions to the many distinct subtypes of vagal sensory neurons. Here, we use genetically guided anatomical tracing, optogenetics, and electrophysiology to identify and characterize vagal sensory neuron subtypes expressing Prox2 and Runx3 in mice. We show that three of these neuronal subtypes innervate the esophagus and stomach in regionalized patterns, where they form intraganglionic laminar endings. Electrophysiological analysis revealed that they are low-threshold mechanoreceptors but possess different adaptation properties. Lastly, genetic ablation of Prox2 and Runx3 neurons demonstrated their essential roles for esophageal peristalsis in freely behaving mice. Our work defines the identity and function of the vagal neurons that provide mechanosensory feedback from the esophagus to the brain and could lead to better understanding and treatment of esophageal motility disorders.

Two Bariatric Surgical Procedures Differentially Alter the Intestinal Microbiota in Obesity Patients.

AIMS: To explore the intestinal microbiota composition affected by the two most widely used procedures of bariatric surgery, laparoscopic sleeve gastrectomy (LSG) and laparoscopic roux-en-Y gastric bypass (LRYGB), in Chinese obesity patients. METHODS: Stool samples were collected from the obese patients before (n = 87) and with follow-up after the surgery (n = 53). After DNA extraction, 16S rDNA (V3 + V4 regions) sequencing was completed on Illumina HiSeq 2500 sequencing platform. The samples were analyzed base on four groups, pre-LSG (n = 54), pre-LRYGB (n = 33), post-LSG (n = 33), and post-LRYGB (n = 20). The linear mixed models were used to analyze the alteration of intestinal microbiota before and after the surgeries of LSG or LRYGB. Student's t test and χ2 test were used for analysis of independent groups; Metastats analysis was used to compare the relative abundance of bacteria, and Pearson correlation and Spearman correlation analysis were used to test the correlation between indicated groups. RESULTS: 87 patients were included and 53 (60.92%) of them completed the follow-up (9.60 ± 3.92 months). Body mass index (BMI) decreased from 37.84 ± 6.16 kg/m2 to 26.22 ± 4.33 kg/m2 after LSG and from 45.75 ± 14.26 kg/m2 to 33.15 ± 10.99 kg/m2 after LRYGB. The relative abundance of 5 phyla and 42 genera were altered after the surgery in the cohort. Although no alteration of Firmicutes was observed at phylum level, 54.76% of the altered genera belong to phylum Firmicutes. Both LSG and LRYGB procedures increased the richness and evenness of intestinal microbiota in obese patients after the surgery. Particularly, 33 genera altered after LSG and 19 genera altered after LRYGB, in which 11 genera were common alterations in both procedures. CONCLUSION: Both LSG and LRYGB altered the composition of intestinal microbiota in Chinese obesity patients, and particularly increased the richness and evenness of microbiota. Genera belonging to phylum Firmicutes were the most altered bacteria by bariatric surgery. The procedure of LSG resulted in much more pronounced alteration of the intestinal microbiota abundance than that observed in LRYGB. While different genera were altered after LSG and LRYGB procedures, 10 genera were the common altered genera in both procedures. Bacteria altered after LSG and LRYGB were functionally associated with BMI, and with relieving of the metabolic syndromes.

HDAC4 mutations cause diabetes and induce ß-cell FoxO1 nuclear exclusion.

BACKGROUND: Studying patients with rare Mendelian diabetes has uncovered molecular mechanisms regulating ß-cell pathophysiology. Previous studies have shown that Class IIa histone deacetylases (HDAC4, 5, 7, and 9) modulate mammalian pancreatic endocrine cell function and glucose homeostasis. METHODS: We performed exome sequencing in one adolescent nonautoimmune diabetic patient and detected one de novo predicted disease-causing HDAC4 variant (p.His227Arg). We screened our pediatric diabetes cohort with unknown etiology using Sanger sequencing. In mouse pancreatic ß-cell lines (Min6 and SJ cells), we performed insulin secretion assay and quantitative RT-PCR to measure the ß-cell function transfected with the detected HDAC4 variants and wild type. We carried out immunostaining and Western blot to investigate if the detected HDAC4 variants affect the cellular translocation and acetylation status of Forkhead box protein O1 (FoxO1) in the pancreatic ß-cells. RESULTS: We discovered three HDAC4 mutations (p.His227Arg, p.Asp234Asn, and p.Glu374Lys) in unrelated individuals who had nonautoimmune diabetes with various degrees of ß-cell loss. In mouse pancreatic ß-cell lines, we found that these three HDAC4 mutations decrease insulin secretion, down-regulate ß-cell-specific transcriptional factors, and cause nuclear exclusion of acetylated FoxO1. CONCLUSION: Mutations in HDAC4 disrupt the deacetylation of FoxO1, subsequently decrease the ß-cell function including insulin secretion, resulting in diabetes.

Haploinsufficiency of Insm1 Impairs Postnatal Baseline ß-Cell Mass.

Baseline ß-cell mass is established during the early postnatal period when ß-cells expand. In this study, we show that heterozygous ablation of Insm1 decreases baseline ß-cell mass and subsequently impairs glucose tolerance. When exposed to a high-fat diet or on an ob/ob background, glucose intolerance was more severe in Insm1+/lacZ mice compared with Insm1+/+ mice, although no further decrease in the ß-cell mass was detected. In islets of early postnatal Insm1+/lacZ mice, the cell cycle was prolonged in ß-cells due to downregulation of the cell cycle gene Ccnd1 Although Insm1 had a low affinity for the Ccnd1 promoter compared with other binding sites, binding affinity was strongly dependent on Insm1 levels. We observed dramatically decreased binding of Insm1 to the Ccnd1 promoter after downregulation of Insm1 expression. Furthermore, downregulation of Ccnd1 resulted in a prolonged cell cycle, and overexpression of Ccnd1 rescued cell cycle abnormalities observed in Insm1-deficient ß-cells. We conclude that decreases in Insm1 interfere with ß-cell specification during the early postnatal period and impair glucose homeostasis during metabolic stress in adults. Insm1 levels are therefore a factor that can influence the development of diabetes.

Insm1 controls development of pituitary endocrine cells and requires a SNAG domain for function and for recruitment of histone-modifying factors.

The Insm1 gene encodes a zinc finger factor expressed in many endocrine organs. We show here that Insm1 is required for differentiation of all endocrine cells in the pituitary. Thus, in Insm1 mutant mice, hormones characteristic of the different pituitary cell types (thyroid-stimulating hormone, follicle-stimulating hormone, melanocyte-stimulating hormone, adrenocorticotrope hormone, growth hormone and prolactin) are absent or produced at markedly reduced levels. This differentiation deficit is accompanied by upregulated expression of components of the Notch signaling pathway, and by prolonged expression of progenitor markers, such as Sox2. Furthermore, skeletal muscle-specific genes are ectopically expressed in endocrine cells, indicating that Insm1 participates in the repression of an inappropriate gene expression program. Because Insm1 is also essential for differentiation of endocrine cells in the pancreas, intestine and adrenal gland, it is emerging as a transcription factor that acts in a pan-endocrine manner. The Insm1 factor contains a SNAG domain at its N-terminus, and we show here that the SNAG domain recruits histone-modifying factors (Kdm1a, Hdac1/2 and Rcor1-3) and other proteins implicated in transcriptional regulation (Hmg20a/b and Gse1). Deletion of sequences encoding the SNAG domain in mice disrupted differentiation of pituitary endocrine cells, and resulted in an upregulated expression of components of the Notch signaling pathway and ectopic expression of skeletal muscle-specific genes. Our work demonstrates that Insm1 acts in the epigenetic and transcriptional network that controls differentiation of endocrine cells in the anterior pituitary gland, and that it requires the SNAG domain to exert this function in vivo.