Biotin controls intestinal stem cell mitosis and host-microbiome interactions

Host-diet-microbiota interplay in intestinal nutrition and health

The intestine is populated by a complex and dynamic assortment of microbes, collectively called gut microbiota, that interact with the host and contribute to its metabolism and physiology. Diet is considered a key regulator of intestinal microbiota, as ingested nutrients interact with and shape the resident microbiota composition. Furthermore, recent studies underscore the interplay of dietary and microbiota-derived nutrients, which directly impinge on intestinal stem cells regulating their turnover to ensure a healthy gut barrier. Although advanced sequencing methodologies have allowed the characterization of the human gut microbiome, mechanistic studies assessing diet-microbiota-host interactions depend on the use of genetically tractable models, such as Drosophila melanogaster. In this review, we first discuss the similarities between the human and fly intestines and then we focus on the effects of diet and microbiota on nutrient-sensing signaling cascades controlling intestinal stem cell self-renewal and differentiation, as well as disease. Finally, we underline the use of the Drosophila model in assessing the role of microbiota in gut-related pathologies and in understanding the mechanisms that mediate different whole-body manifestations of gut dysfunction.

Biotin-functionalized nanoparticles: an overview of recent trends in cancer detection

Electrochemical bio-sensing is a potent and efficient method for converting various biological recognition events into voltage, current, and impedance electrical signals. Biochemical sensors are now a common part of medical applications, such as detecting blood glucose levels, detecting food pathogens, and detecting specific cancers. As an exciting feature, bio-affinity couples, such as proteins with aptamers, ligands, paired nucleotides, and antibodies with antigens, are commonly used as bio-sensitive elements in electrochemical biosensors. Biotin-avidin interactions have been utilized for various purposes in recent years, such as targeting drugs, diagnosing clinically, labeling immunologically, biotechnology, biomedical engineering, and separating or purifying biomolecular compounds. The interaction between biotin and avidin is widely regarded as one of the most robust and reliable noncovalent interactions due to its high bi-affinity and ability to remain selective and accurate under various reaction conditions and bio-molecular attachments. More recently, there have been numerous attempts to develop electrochemical sensors to sense circulating cancer cells and the measurement of intracellular levels of protein thiols, formaldehyde, vitamin-targeted polymers, huwentoxin-I, anti-human antibodies, and a variety of tumor markers (including alpha-fetoprotein, epidermal growth factor receptor, prostate-specific Ag, carcinoembryonic Ag, cancer antigen 125, cancer antigen 15-3, etc.). Still, the non-specific binding of biotin to endogenous biotin-binding proteins present in biological samples can result in false-positive signals and hinder the accurate detection of cancer biomarkers. This review summarizes various categories of biotin-functional nanoparticles designed to detect such biomarkers and highlights some challenges in using them as diagnostic tools.

Biotin Homeostasis and Human Disorders: Recent Findings and Perspectives

Biotin (vitamin B7, or vitamin H) is a water-soluble B-vitamin that functions as a cofactor for carboxylases, i.e., enzymes involved in the cellular metabolism of fatty acids and amino acids and in gluconeogenesis; moreover, as reported, biotin may be involved in gene regulation. Biotin is not synthesized by human cells, but it is found in food and is also produced by intestinal bacteria. Biotin status/homeostasis in human individuals depends on several factors, including efficiency/deficiency of the enzymes involved in biotin recycling within the human organism (biotinidase, holocarboxylase synthetase), and/or effectiveness of intestinal uptake, which is mainly accomplished through the sodium-dependent multivitamin transporter. In the last years, administration of biotin at high/"pharmacological" doses has been proposed to treat specific defects/deficiencies and human disorders, exhibiting mainly neurological and/or dermatological symptoms and including biotinidase deficiency, holocarboxylase synthetase deficiency, and biotin-thiamine-responsive basal ganglia disease. On the other hand, according to warnings of the Food and Drug Administration, USA, high biotin levels can affect clinical biotin-(strept)avidin assays and thus lead to false results during quantification of critical biomarkers. In this review article, recent findings/advancements that may offer new insight in the abovementioned research fields concerning biotin will be presented and briefly discussed.

Recurrent "outsider" intronic variation in the SLC5A6 gene causes severe mixed axonal and demyelinating neuropathy, cyclic vomiting and optic atrophy in 3 families from Maghreb

Sodium dependent multivitamin transporter (SMVT) deficiency is a very rare autosomal recessive disorder characterized by multisystemic clinical manifestations due to combined biotin, panthotenic acid and lipoic acid deficiency. About 10 families have been described so far. Accurate diagnosis is crucial because of the possibility of a supplementation treatment with proven efficacy. Here we describe 4 new patients (3 additional families) originating from the same world region (Algeria, Maghreb). All patients, born form consanguineous parents, were homozygous carriers of the same intronic variation, outside of canonical sites, in the SLC5A6 gene encoding SMVT. RNA study in one family allowed confirming the pathogenic effect of the variation and re-classifying this variant of uncertain significance as pathogenic, opening the possibility of genetic counseling and treatment. The identification of the same variation in three distinct and apparently unrelated families is suggestive of a founder effect. The phenotype of all patients was very similar, with systematic optic atrophy (initially considered as a very rare sign), severe cyclic vomiting, and rapidly progressive mixed axonal and demyelinating sensory motor neuropathy.

Host-microbiota interaction in intestinal stem cell homeostasis

Intestinal stem cells (ISCs) play a pivotal role in gut physiology by governing intestinal epithelium renewal through the precise regulation of proliferation and differentiation. The gut microbiota interacts closely with the epithelium through myriad of actions, including immune and metabolic interactions, which translate into tight connections between microbial activity and ISC function. Given the diverse functions of the gut microbiota in affecting the metabolism of macronutrients and micronutrients, dietary nutrients exert pronounced effects on host-microbiota interactions and, consequently, the ISC fate. Therefore, understanding the intricate host-microbiota interaction in regulating ISC homeostasis is imperative for improving gut health. Here, we review recent advances in understanding host-microbiota immune and metabolic interactions that shape ISC function, such as the role of pattern-recognition receptors and microbial metabolites, including lactate and indole metabolites. Additionally, the diverse regulatory effects of the microbiota on dietary nutrients, including proteins, carbohydrates, vitamins, and minerals (e.g. iron and zinc), are thoroughly explored in relation to their impact on ISCs. Thus, we highlight the multifaceted mechanisms governing host-microbiota interactions in ISC homeostasis. Insights gained from this review provide strategies for the development of dietary or microbiota-based interventions to foster gut health.

Multi-omics analyses demonstrate the modulating role of gut microbiota on the associations of unbalanced dietary intake with gastrointestinal symptoms in children with autism spectrum disorder

Our previous work revealed that unbalanced dietary intake was an important independent factor associated with constipation and gastrointestinal (GI) symptoms in children with autism spectrum disorder (ASD). Growing evidence has shown the alterations in the gut microbiota and gut microbiota-derived metabolites in ASD. However, how the altered microbiota might affect the associations between unbalanced diets and GI symptoms in ASD remains unknown. We analyzed microbiome and metabolomics data in 90 ASD and 90 typically developing (TD) children based on 16S rRNA and untargeted metabolomics, together with dietary intake and GI symptoms assessment. We found that there existed 11 altered gut microbiota (FDR-corrected P-value <0.05) and 397 altered metabolites (P-value <0.05) in children with ASD compared with TD children. Among the 11 altered microbiota, the Turicibacter, Coprococcus 1, and Lachnospiraceae FCS020 group were positively correlated with constipation (FDR-corrected P-value <0.25). The Eggerthellaceae was positively correlated with total GI symptoms (FDR-corrected P-value <0.25). More importantly, three increased microbiota including Turicibacter, Coprococcus 1, and Eggerthellaceae positively modulated the associations of unbalanced dietary intake with constipation and total GI symptoms, and the decreased Clostridium sp. BR31 negatively modulated their associations in ASD children (P-value <0.05). Together, the altered microbiota strengthens the relationship between unbalanced dietary intake and GI symptoms. Among the altered metabolites, ten metabolites derived from microbiota (Turicibacter, Coprococcus 1, Eggerthellaceae, and Clostridium sp. BR31) were screened out, enriched in eight metabolic pathways, and were identified to correlate with constipation and total GI symptoms in ASD children (FDR-corrected P-value <0.25). These metabolomics findings further support the modulating role of gut microbiota on the associations of unbalanced dietary intake with GI symptoms. Collectively, our research provides insights into the relationship between diet, the gut microbiota, and GI symptoms in children with ASD.

Gut microbiota bridges dietary nutrients and host immunity

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other, and thus affect host health and immune-mediated diseases. Here, we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions, emphasizing how this axis might influence host immunity in health and diseases. Of relevance, we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

The Sterol Transporter Npc2c Controls Intestinal Stem Cell Mitosis and Host-Microbiome Interactions in Drosophila

Cholesterol is necessary for all cells to function. The intracellular cholesterol transporters Npc1 and Npc2 control sterol trafficking and their malfunction leads to Neimann-Pick Type C disease, a rare disorder affecting the nervous system and the intestine. Unlike humans that encode single Npc1 and Npc2 transporters, flies encompass two Npc1 (Npc1a-1b) and eight Npc2 (Npc2a-2h) members, and most of the Npc2 family genes remain unexplored. Here, we focus on the intestinal function of Npc2c in the adult. We find that Npc2c is necessary for intestinal stem cell (ISC) mitosis, maintenance of the ISC lineage, survival upon pathogenic infection, as well as tumor growth. Impaired mitosis of Npc2c-silenced midguts is accompanied by reduced expression of Cyclin genes, and genes encoding ISC regulators, such as Delta, unpaired1 and Socs36E. ISC-specific Npc2c silencing induces Attacin-A expression, a phenotype reminiscent of Gram-negative bacteria overabundance. Metagenomic analysis of Npc2c-depleted midguts indicates intestinal dysbiosis, whereby decreased commensal complexity is accompanied by increased gamma-proteobacteria. ISC-specific Npc2c silencing also results in increased cholesterol aggregation. Interestingly, administration of the non-steroidal ecdysone receptor agonist, RH5849, rescues mitosis of Npc2c-silenced midguts and increases expression of the ecdysone response gene Broad, underscoring the role of Npc2c and sterols in ecdysone signaling. Assessment of additional Npc2 family members indicates potential redundant roles with Npc2c in ISC control and response to ecdysone signaling. Our results highlight a previously unidentified essential role of Npc2c in ISC mitosis, as well as an important role in ecdysone signaling and microbiome composition in the Drosophila midgut.

Intestinal stem cells and their niches in homeostasis and disease

Tissues such as the intestine harbor stem cells that have remarkable functional plasticity in response to a dynamic environment. To adapt to the environment, stem cells constantly receive information from their surrounding microenvironment (also called the 'niche') that instructs them how to adapt to changes. The Drosophila midgut shows morphological and functional similarities to the mammalian small intestine and has been a useful model system to study signaling events in stem cells and tissue homeostasis. In this review, we summarize the current understanding of the Drosophila midgut regarding how stem cells communicate with microenvironmental niches including enteroblasts, enterocytes, enteroendocrine cells and visceral muscles to coordinate tissue regeneration and homeostasis. In addition, distant cells such as hemocytes or tracheal cells have been shown to interact with stem cells and influence the development of intestinal diseases. We discuss the contribution of stem cell niches in driving or counteracting disease progression, and review conceptual advances derived from the Drosophila intestine as a model for stem cell biology.

Analysis and application of RNA binding protein gene pairs to predict the prognosis of gastric cancer

Background

RNA-binding proteins (RBPs) are closely related to tumors, but little is known about the mechanism of RBPs in tumorigenesis and progression of gastric cancer (GC). As genes do not usually act alone in the pathway deregulation, gene pair combinations are more likely to become stable and accurate biomarkers. The purpose of our research is to establish a novel signature based on RBP gene pairs to predict the prognosis of gastric cancer patients.

Methods

We downloaded genetic and clinical information from the TCGA and GEO database. TCGA and GSE13911 were used for screening differentially expressed genes (DEGs). The RBP genes were gathered from previous studies and employed to screen out DE-RBP genes after intersecting with DEGs. Samples were classified according to the relative expression of each pair of DE-RBP genes. The univariate Cox regression analysis and random forest were used to identify hub gene pairs to construct signature for predicting the prognosis of gastric cancer. Time-dependent ROC curves and KM survival curves were performed to evaluate the signature. GSEA was performed in TCGA training cohort and GSE62254 testing cohort to analyze enrichment pathways. Finally, the influence of these gene pairs on the prognosis of GC patients was further elucidated respectively through the combination of high and low expression of the two genes in each hub gene pair.

Results

We screened out 6 hub RBP gene pairs (COL5A2/FEN1, POP1/GFRA1, EXO1/PLEKHS1, SLC39A10/CHI3L1, MMP7/PPP1R1 B and SLC5A6/BYSL) to predict the prognosis of patients with gastric cancer. Using the optimal cut-off value to divide patients into high-risk and low-risk groups in the training and testing cohort, we found that the overall survival (OS) of the low-risk group was higher than that of the high-risk group (P < 0.05). The area under the ROC curves for 1, 3, and 5 years were (0.659, 0.744, 0.758) and (0.624, 0.650, 0.653) in two cohorts. Univariate and multivariate Cox regression analysis showed that 6 RBP gene pairs signature were independent prognostic factors for gastric cancer (P < 0.05). In addition, the prognostic survival analysis showed that COL5A2-high/FEN1-low, POP1-low/GFRA1-high, EXO1-low/PLEKHS1-low,SLC39A10-high/CHI3L1-low, MMP7-high/PPP1R1 B-low, SLC5A6-low/BYSL-low had worse OS (P < 0.05). And the gene correlation analysis showed that there was no obvious correlation between the genes in each gene pairs except SLC5A6/BYSL and POP1/GFRA1. Finally, GSEA analysis showed that the high-risk group was enriched in tumor migration, invasion and growth-related pathways.

Conclusion

Our study identified a novel 6 RBP gene pairs signature to predict the prognosis of gastric cancer patients and provide potential targets for clinical gene therapy.

A novel SLC5A6 homozygous variant in a family with multivitamin-dependent neurometabolic disorder: Phenotype expansion and long-term follow-up

The sodium-dependent multivitamin transporter (hSMVT) encoded by the SLC5A6 gene is required for the intestinal absorption of biotin, pantothenic acid and lipoate, three micronutrients essential for normal growth and development. Systemic deficiency of these elements, either occurring from nutritional causes or genetic defects, is associated with neurological disorders, growth delay, skin and hair changes, metabolic and immunological abnormalities. A few patients with biallelic variants of SLC5A6 have been reported, exhibiting a spectrum of neurological and systemic clinical features with variable severity. We describe three patients from a single family carrying a homozygous p.(Leu566Valfs*33) variant of SLC5A6 disrupting the frame of the C-terminal portion of the hSMVT. In these patients, we documented a severe disorder featuring developmental delay, sensory polyneuropathy, optic atrophy, recurrent infections, and repeated episodes of intestinal pseudo-obstruction. Two patients who did not receive multivitamin supplementation therapy died in early infancy. In a third patient, early supplementation of biotin and pantothenic acid stabilized the clinical picture changing the course of the disease. These findings extend genotype-phenotype correlations and show how a timely and lifelong multivitamin treatment may be crucial to reduce the risk of life-threatening events in patients with pathogenic variants of the SLC5A6 gene.

Eucommia Polysaccharides Ameliorate Aging-Associated Gut Dysbiosis: A Potential Mechanism for Life Extension in Drosophila

The gut microbiota is increasingly considered to play a key role in human immunity and health. The aging process alters the microbiota composition, which is associated with inflammation, reactive oxygen species (ROS), decreased tissue function, and increased susceptibility to age-related diseases. It has been demonstrated that plant polysaccharides have beneficial effects on the gut microbiota, particularly in reducing pathogenic bacteria abundance and increasing beneficial bacteria populations. However, there is limited evidence of the effect of plant polysaccharides on age-related gut microbiota dysbiosis and ROS accumulation during the aging process. To explore the effect of Eucommiae polysaccharides (EPs) on age-related gut microbiota dysbiosis and ROS accumulation during the aging process of Drosophila, a series of behavioral and life span assays of Drosophila with the same genetic background in standard medium and a medium supplemented with EPs were performed. Next, the gut microbiota composition and protein composition of Drosophila in standard medium and the medium supplemented with EPs were detected using 16S rRNA gene sequencing analysis and quantitative proteomic analysis. Here, we show that supplementation of Eucommiae polysaccharides (EPs) during development leads to the life span extension of Drosophila. Furthermore, EPs decreased age-related ROS accumulation and suppressed Gluconobacter, Providencia, and Enterobacteriaceae in aged Drosophila. Increased Gluconobacter, Providencia, and Enterobacteriaceae in the indigenous microbiota might induce age-related gut dysfunction in Drosophila and shortens their life span. Our study demonstrates that EPs can be used as prebiotic agents to prevent aging-associated gut dysbiosis and reactive oxidative stress.

Involvement of Microbiota in Insect Physiology: Focus on B Vitamins

Insects are highly successful in colonizing a wide spectrum of ecological niches and in feeding on a wide diversity of diets. This is notably linked to their capacity to get from their microbiota any essential component lacking in the diet such as vitamins and amino acids. Over a century of research based on dietary analysis, antimicrobial treatment, gnotobiotic rearing, and culture-independent microbe detection progressively generated a wealth of information about the role of the microbiota in specific aspects of insect fitness. Thanks to the recent increase in sequencing capacities, whole-genome sequencing of a number of symbionts has facilitated tracing of biosynthesis pathways, validation of experimental data and evolutionary analyses. This field of research has generated a considerable set of data in a diversity of hosts harboring specific symbionts or nonspecific microbiota members. Here, we review the current knowledge on the involvement of the microbiota in insect and tick nutrition, with a particular focus on B vitamin provision. We specifically question if there is any specificity of B vitamin provision by symbionts compared to the redundant yet essential contribution of nonspecific microbes. We successively highlight the known aspects of microbial vitamin provision during three main life stages of invertebrates: postembryonic development, adulthood, and reproduction.

The opportunistic pathogen Pseudomonas aeruginosa exploits bacterial biotin synthesis pathway to benefit its infectivity

Pseudomonas aeruginosa is an opportunistic pathogen that predominantly causes nosocomial and community-acquired lung infections. As a member of ESKAPE pathogens, carbapenem-resistant P. aeruginosa (CRPA) compromises the limited therapeutic options, raising an urgent demand for the development of lead compounds against previously-unrecognized drug targets. Biotin is an important cofactor, of which the de novo synthesis is an attractive antimicrobial target in certain recalcitrant infections. Here we report genetic and biochemical definition of P. aeruginosa BioH (PA0502) that functions as a gatekeeper enzyme allowing the product pimeloyl-ACP to exit from fatty acid synthesis cycle and to enter the late stage of biotin synthesis pathway. In relative to Escherichia coli, P. aeruginosa physiologically requires 3-fold higher level of cytosolic biotin, which can be attributed to the occurrence of multiple biotinylated enzymes. The BioH protein enables the in vitro reconstitution of biotin synthesis. The repertoire of biotin abundance is assigned to different mouse tissues and/or organ contents, and the plasma biotin level of mouse is around 6-fold higher than that of human. Removal of bioH renders P. aeruginosa biotin auxotrophic and impairs its intra-phagosome persistence. Based on a model of CD-1 mice mimicking the human environment, lung challenge combined with systemic infection suggested that BioH is necessary for the full virulence of P. aeruginosa. As expected, the biotin synthesis inhibitor MAC13772 is capable of dampening the viability of CRPA. Notably, MAC13772 interferes the production of pyocyanin, an important virulence factor of P. aeruginosa. Our data expands our understanding of P. aeruginosa biotin synthesis relevant to bacterial infectivity. In particular, this study represents the first example of an extracellular pathogen P. aeruginosa that exploits biotin cofactor as a fitness determinant, raising the possibility of biotin synthesis as an anti-CRPA target.

Host Microbiomes Influence the Effects of Diet on Inflammation and Cancer

Cancer is the second leading cause of death globally, and there is a growing appreciation for the complex involvement of diet, microbiomes, and inflammatory processes culminating in tumorigenesis. Although research has significantly improved our understanding of the various factors involved in different cancers, the underlying mechanisms through which these factors influence tumor cells and their microenvironment remain to be completely understood. In particular, interactions between the different microbiomes, specific dietary factors, and host cells mediate both local and systemic immune responses, thereby influencing inflammation and tumorigenesis. Developing an improved understanding of how different microbiomes, beyond just the colonic microbiome, can interact with dietary factors to influence inflammatory processes and tumorigenesis will support our ability to better understand the potential for microbe-altering and dietary interventions for these patients in future.

Tiny Drosophila intestinal stem cells, big power

The signaling pathways are highly conserved between Drosophila and mammals concerning intestinal development, regeneration, and disease. The powerful genetic tools of Drosophila make it a valuable and convenient alternative to answer basic biological questions that can not be addressed using mammalian models. In this review, we discuss recent advances in how we use fly midgut to answer the following key questions: (1) How intestine stem cell niches are established; (2) which factors control asymmetric division of stem cells; (3) how intestinal cells interact with environmental factors, such as tissue damage, microbiota, and diet; (4) how to screen aging/cancer-related factors or drugs by fly intestine stem cells.