title: Conditional postnatal deletion of the neonatal murine hepatic circadian gene, Npas2, alters the gut microbiome following restricted feeding.
abstract: We have recently shown in both non-human primates and in rodents that fetal and neonatal hepatic expression of the circadian transcription factor, Npas2, is modulated by a high fat maternal diet and plays a critical role in establishing life-long metabolic homeostasis. Similarly, we and others have also established the importance of the maternal and early postnatal diet on establishment of the early gut microbiome.
  
  
  
  We hypothesized that altered circadian gene expression solely in the neonatal liver would result in gut microbiome dysbiosis, especially with diet-induced metabolic stress (ie, restricted feeding). Using a murine model in which we conditionally knock out Npas2 in the neonatal liver, we aimed to determine the role of the circadian machinery in gut dysbiosis with restricted feeding.
  
  
  
  We collected fecal samples from liver Npas2 conditional knockout (n = 11) and wild-type (n = 13) reproductive-aged mice before (study day 0) and after the restricted feeding study (study day 17). Extracted DNA was sequenced using the MiSeq Illumina platform using primers specific for the V4 region of the 16S ribosomal DNA gene. The resulting sequences were quality filtered, aligned, and assigned taxonomy. Principal coordinate analysis was performed on unweighted and weighted UniFrac distances between samples with a permutation analysis of variance to assess clustering significance between groups. Microbial taxa that significantly differ between groups of interest was determined using linear discriminate analysis effect size and randomForrest.
  
  
  
  Principal coordinate analysis performed on weighted UniFrac distances between male conditional knockout and wild-type cohorts revealed that the gut microbiome of the mice did not differ by genotype at the start of the restricted feeding study but did differ by virtue of genotype at the end of the study (P = .001). Moreover, these differences could be at least partially attributed to restricted feeding-associated alterations in relative abundance of the Bacteroides genus, which has been implicated as crucial to establishing a healthy gut microbiome early in development.
  
  
  
  Here we have provided an initial key insight into the interplay between neonatal establishment of the peripheral circadian clock in the liver and the ability of the gut microbiome to respond to dietary and metabolic stress. Because Npas2 expression in the liver is a target of maternal high-fat diet-induced metabolic perturbations during fetal development, we speculate that these findings have potential implications in the long-term metabolic health of their offspring.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Baylor College of Medicine, Houston, TX; Interdepartmental Graduate Program of Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX.
authors.forename: Derek S
authors.initials: DS
authors.lastname: O'Neil
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Stewart
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Baylor College of Medicine, Houston, TX; Interdepartmental Graduate Program of Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX.
authors.forename: Derrick M
authors.initials: DM
authors.lastname: Chu
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Baylor College of Medicine, Houston, TX.
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Goodspeed
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Baylor College of Medicine, Houston, TX.
authors.forename: Pablo J
authors.initials: PJ
authors.lastname: Gonzalez-Rodriguez
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Baylor College of Medicine, Houston, TX.
authors.forename: Cynthia D
authors.initials: CD
authors.lastname: Shope
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Baylor College of Medicine, Houston, TX; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX; Department of Molecular and Cell Biology, Baylor College of Medicine, Houston, TX; Department of Molecular and Cellular Physiology, Baylor College of Medicine, Houston, TX; Interdepartmental Graduate Program of Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX. Electronic address: aagaardt@bcm.edu.
authors.forename: Kjersti M
authors.initials: KM
authors.lastname: Aagaard
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D002940:Circadian Rhythm; D004032:Diet; D005260:Female; D000069196:Gastrointestinal Microbiome / Q000235:genetics*; D005786:Gene Expression Regulation; D008297:Male; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009419:Nerve Tissue Proteins; C491259:Npas2 protein, mouse
keywords: Npas2; gut microbiome; mouse model; peripheral circadian clock; restricted feeding