Major urinary protein 5, a scent communication protein, is regulated by dietary restriction and subsequent re-feeding in mice

Major urinary protein (Mup) gene family deletion drives sex-specific alterations in the house-mouse gut microbiota

The gut microbiota is shaped by host metabolism. In house mice (Mus musculus), major urinary protein (MUP) pheromone production represents a considerable energy investment, particularly in sexually mature males. Deletion of the Mup gene family shifts mouse metabolism toward an anabolic state, marked by lipogenesis, lipid accumulation, and body mass increases. Given the metabolic implications of MUPs, they may also influence the gut microbiota. Here, we investigated the effect of a deletion of the Mup gene family on the gut microbiota of sexually mature mice. Shotgun metagenomics revealed distinct taxonomic and functional profiles between wild-type and knockout males but not females. Deletion of the Mup gene cluster significantly reduced diversity in microbial families and functions in male mice. Additionally, a species of Ruminococcaceae and several microbial functions, such as transporters involved in vitamin B5 acquisition, were significantly depleted in the microbiota of Mup knockout males. Altogether, these results show that MUPs significantly affect the gut microbiota of house mouse in a sex-specific manner.IMPORTANCEThe community of microorganisms that inhabits the gastrointestinal tract can have profound effects on host phenotypes. The gut microbiota is in turn shaped by host genes, including those involved with host metabolism. In adult male house mice, expression of the major urinary protein (Mup) gene cluster represents a substantial energy investment, and deletion of the Mup gene family leads to fat accumulation and weight gain in males. We show that deleting Mup genes also alters the gut microbiota of male, but not female, mice in terms of both taxonomic and functional compositions. Male mice without Mup genes harbored fewer gut bacterial families and reduced abundance of a species of Ruminococcaceae, a family that has been previously shown to reduce obesity risk. Studying the impact of the Mup gene family on the gut microbiota has the potential to reveal the ways in which these genes affect host phenotypes.

Major urinary protein (Mup) gene family deletion drives sex-specific alterations on the house mouse gut microbiota

The gut microbiota is shaped by host metabolism. In house mice (Mus musculus), major urinary protein (MUP) pheromone production represents a considerable energy investment, particularly in sexually mature males. Deletion of the Mup gene family shifts mouse metabolism towards an anabolic state, marked by lipogenesis, lipid accumulation, and body mass increases. Given the metabolic implications of MUPs, they may also influence the gut microbiota. Here, we investigated the effect of deletion of the Mup gene family on the gut microbiota of sexually mature mice. Shotgun metagenomics revealed distinct taxonomic and functional profiles between wildtype and knockout males, but not females. Deletion of the Mup gene cluster significantly reduced diversity in microbial families and functions in male mice. Additionally, specific taxa of the Ruminococcaceae family, which is associated with gut health and reduced risk of developing metabolic syndrome, and several microbial functions, such as transporters involved in vitamin B5 acquisition, were significantly depleted in the microbiota of Mup-knockout males. Altogether these results show that major urinary proteins significantly affect the gut microbiota of house mouse in a sex-specific manner.

Caloric restriction delays age-related muscle atrophy by inhibiting 11β-HSD1 to promote the differentiation of muscle stem cells

Introduction

Calorie restriction (CR) is an important direction for the delay of sarcopenia in elderly individuals. However, the specific mechanisms of CR against aging are still unclear.

Methods

In this study, we used a CR model of elderly mice with muscle-specific 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) knockout mice and 11β-HSD1 overexpression mice to confirm that CR can delay muscle aging by inhibiting 11β-HSD1 which can transform inactive GC(cortisone) into active GC(cortisol). The ability of self-proliferation and differentiation into muscle fibers of these mouse muscle stem cells (MuSCs) was observed in vitro. Additionally, the mitochondrial function and mitochondrial ATP production capacity of MuSCs were measured by mitochondrial oxygen consumption.

Results

It was found that the 11β-HSD1 expression level was increased in age-related muscle atrophy. Overexpression of 11β-HSD1 led to muscle atrophy in young mice, and 11β-HSD1 knockout rescued age-related muscle atrophy. Moreover, CR in aged mice reduced the local effective concentration of glucocorticoid (GC) through 11β-HSD1, thereby promoting the mitochondrial function and differentiation ability of MuSCs.

Conclusions

Together, our findings highlight promising sarcopenia protection with 40% CR in older ages. Furthermore, we speculated that targeting an 11β-HSD1-dependent metabolic pathway may represent a novel strategy for developing therapeutics against age-related muscle atrophy.

The major urinary protein gene cluster knockout mouse as a novel model for translational metabolism research

Scientific evidence suggests that not only murine scent communication is regulated by major urinary proteins, but that their expression may also vary in response to metabolism via a yet unknown mechanism. Major urinary proteins are expressed mainly in the liver, showing a sexually dimorphic pattern with substantially higher expression in males. Here, we investigate the metabolic implications of a major urinary protein knockout in twelve-week-old male and female C57BL/6N mice during ad libitum feeding. Despite both sexes of major urinary protein knockout mice displayed numerically increased body weight and visceral adipose tissue proportions compared to sex-matched wildtype mice, the main genotype-specific metabolic differences were observed exclusively in males. Male major urinary protein knockout mice exhibited plasma and hepatic lipid accumulation accompanied by a hepatic transcriptome indicating an activation of lipogenesis. These findings match the higher major urinary protein expression in male compared to female wildtype mice, suggesting a more distinct reduction in energy requirements in male compared to female major urinary protein knockout mice. The observed sex-specific anabolic phenotype confirms a role of major urinary protein in metabolism and, since major urinary proteins are not expressed in humans, suggests the major urinary protein knockout mouse as a potential alternative model for translational metabolism research which needs to be further elucidated.

The Impact of Varying Food Availability on Gene Expression in the Liver: Testing the Match-Mismatch Hypothesis

Background

During early phases of life, such as prenatal or early postnatal development and adolescence, an organism's phenotype can be shaped by the environmental conditions it experiences. According to the Match-Mismatch hypothesis (MMH), changes to this environment during later life stages can result in a mismatch between the individual's adaptations and the prevailing environmental conditions. Thus, negative consequences in welfare and health can occur. We aimed to test the MMH in the context of food availability, assuming adolescence as a sensitive period of adaptation.

Methods

We have previously reported a study of the physiological and behavioral effects of match and mismatch conditions of high (ad libitum) and low (90% of ad libitum intake) food availability from adolescence to early adulthood in female C57BL/6J mice (n = 62). Here, we performed RNA-sequencing of the livers of a subset of these animals (n = 16) to test the effects of match and mismatch feeding conditions on the liver transcriptome.

Results

In general, we found no effect of the match-mismatch situations. Contrarily, the amount of food available during early adulthood (low vs. high) drove the differences we observed in final body weight and gene expression in the liver, regardless of the amount of food available to the animals during adolescence. Many of the differentially expressed genes and the corresponding biological processes found to be overrepresented overlapped, implicating common changes in various domains. These included metabolism, homeostasis, cellular responses to diverse stimuli, transport of bile acids and other molecules, cell differentiation, major urinary proteins, and immunity and inflammation.

Conclusions

Our previous and present observations found no support for the MMH in the context of low vs high food availability from adolescence to early adulthood in female C57BL/6J mice. However, even small differences of approximately 10% in food availability during early adulthood resulted in physiological and molecular changes with potential beneficial implications for metabolic diseases.

Regulation of Sexually Dimorphic Expression of Major Urinary Proteins

Male house mice excrete large amounts of protein in their urinary scent marks, mainly composed of Major Urinary Proteins (MUPs), and these lipocalins function as pheromones and pheromone carriers. Here, we review studies on sexually dimorphic MUP expression in house mice, including the proximate mechanisms controlling MUP gene expression and their adaptive functions. Males excrete 2 to 8 times more urinary protein than females, though there is enormous variation in gene expression across loci in both sexes. MUP expression is dynamically regulated depending upon a variety of factors. Males regulate MUP expression according to social status, whereas females do not, and males regulate expression depending upon health and condition. Male-biased MUP expression is regulated by pituitary secretion of growth hormone (GH), which binds receptors in the liver, activating the JAK2-STAT5 signaling pathway, chromatin accessibility, and MUP gene transcription. Pulsatile male GH secretion is feminized by several factors, including caloric restriction, microbiota depletion, and aging, which helps explain condition-dependent MUP expression. If MUP production has sex-specific fitness optima, then this should generate sexual antagonism over allelic expression (intra-locus sexual conflict) selectively favoring sexually dimorphic expression. MUPs influence the sexual attractiveness of male urinary odor and increased urinary protein excretion is correlated with the reproductive success of males but not females. This finding could explain the selective maintenance of sexually dimorphic MUP expression. Producing MUPs entails energetic costs, but increased excretion may reduce the net energetic costs and predation risks from male scent marking as well as prolong the release of chemical signals. MUPs may also provide physiological benefits, including regulating metabolic rate and toxin removal, which may have sex-specific effects on survival. A phylogenetic analysis on the origins of male-biased MUP gene expression in Mus musculus suggests that this sexual dimorphism evolved by increasing male MUP expression rather than reducing female expression.

Intergenerational effects of a paternal Western diet during adolescence on offspring gut microbiota, stress reactivity, and social behavior

The global consumption of highly processed, calorie-dense foods has contributed to an epidemic of overweight and obesity, along with negative consequences for metabolic dysfunction and disease susceptibility. As it becomes apparent that overweight and obesity have ripple effects through generations, understanding of the processes involved is required, in both maternal and paternal epigenetic inheritance. We focused on the patrilineal effects of a Western-style high-fat (21%) and high-sugar (34%) diet (WD) compared to control diet (CD) during adolescence and investigated F0 and F1 mice for physiological and behavioral changes. F0 males (fathers) showed increased body weight, impaired glycemic control, and decreased attractiveness to females. Paternal WD caused significant phenotypic changes in F1 offspring, including higher body weights of pups, increased Actinobacteria abundance in the gut microbiota (ascertained using 16S microbiome profiling), a food preference for WD pellets, increased male dominance and attractiveness to females, as well as decreased behavioral despair. These results collectively demonstrate the long-term intergenerational effects of a Western-style diet during paternal adolescence. The behavioral and physiological alterations in F1 offspring provide evidence of adaptive paternal programming via epigenetic inheritance. These findings have important implications for understanding paternally mediated intergenerational inheritance, and its relevance to offspring health and disease susceptibility.

Urinary protein analysis in mice lacking major urinary proteins

Mouse urine contains major urinary proteins (MUPs) that are not found in human urine. Therefore, even healthy mice exhibit proteinuria, unlike healthy humans, making it challenging to use mice as models for human diseases. It was also unknown whether dipsticks for urinalysis could measure protein concentrations precisely in urine containing MUPs. To resolve these problems, we produced MUP-knockout (Mup-KO) mice by removing the Mup gene cluster using Cas9 proteins and two guide RNAs and characterized the urinary proteins in these mice. We measured the urinary protein concentrations in Mup-KO and wild-type mice using a protein quantitation kit and dipsticks. We also examined the urinary protein composition using SDS-PAGE and two-dimensional electrophoresis (2DE). The urinary protein concentration was significantly lower (P<0.001) in Mup-KO mice (17.9 ± 1.8 mg/dl, mean ± SD, n=3) than in wild-type mice (73.7 ± 8.2 mg/dl, n=3). This difference was not reflected in the dipstick values, perhaps due to the low sensitivity to MUPs. This suggests that dipsticks have limited ability to measure changes in MUPs with precision. SDS-PAGE and 2DE confirmed that Mup-KO mice, like humans, had no MUPs in their urine, whereas wild-type mice had abundant MUPs in their urine. The absence of the masking effect of MUPs in 2DE would enable clear comparisons of urinary proteins, especially low-molecular-weight proteins. Thus, Mup-KO mice may provide a useful model for human urinalysis.

In Contrast to Dietary Restriction, Application of Resveratrol in Mice Does not Alter Mouse Major Urinary Protein Expression

Resveratrol (RSV) supplementation in mice has been discussed as partly mimicking the beneficial effects of dietary restriction (DR). However, data on putative benefits from resveratrol application in mice and other model organisms including humans is contradictory. Mouse major urinary proteins (MUPs) are a family of proteins that are expressed in rodent liver and secreted via urine. Impacting (mating) behavior and pheromone communication, they are severely down-regulated upon DR. We carried out two studies in C57BL/6Rj mice where RSV was either supplemented via diet or injected intraperitoneally for 8 weeks. Contrary to −40% DR, RSV did not decrease total MUP protein expression or Mup (amongst others Mup3, Mup5, Mup6, Mup15, and Mup20) mRNA levels in mouse liver when compared to ad-libitum (AL)-fed controls. Since inhibitory glucocorticoid response elements can be found in Mup promoters, we also measured glucocorticoid receptor (GR) levels in nuclear hepatic extracts. Consistent with differential MUP expression, we observed more nuclear GR in DR mice than in RSV-supplemented and AL control mice with no difference between RSV and AL. These findings point to the notion that, in mice, RSV does not mimic DR in terms of differential MUP expression.

Immunochromatographic assay to detect α-tubulin in urine for the diagnosis of kidney injury

Backgrounds

Shortening of primary cilia in kidney epithelial cells is associated with kidney injury and involved with the induced level of α‐tubulin in urine. Therefore, rapid detection and quantification of α‐tubulin in the urine samples could be used to the preliminary diagnosis of kidney injury.

Methods

Cellulose‐based nanobeads modified with α‐tubulin were used for the detection probe of competitive immunochromatographic (IC) assay. The concentration of α‐tubulin in the urine samples was determined by IC assay and compared with the amount determined by Western blotting analysis.

Results

The relationship between α‐tubulin concentration and the colorimetric intensity resulted from IC assay was determined by logistic regression, and the correlation coefficient (R²) was 0.9948. When compared to the amount determined by Western blotting analysis, there was a linear relationship between the α‐tubulin concentrations measured by the two methods and the R² value was 0.823.

Conclusions

This method is simple, rapid, and adequately sensitive to detect α‐tubulin in patient urine samples, which could be used for the clinical diagnosis of kidney injury.

Resveratrol, lunularin and dihydroresveratrol do not act as caloric restriction mimetics when administered intraperitoneally in mice

Resveratrol as well as caloric restriction were shown to extend lifespan in some model organisms and may possibly delay onset of ageing-related diseases in humans. Yet, resveratrol supplementation does not always extend lifespan of animal models or improve health status of humans. Because of interindividual differences in human microbiota, resveratrol metabolite production in the gut differs. While some individuals produce lunularin and dihydroresveratrol in their gut, others produce dihydroresveratrol only. Therefore, we addressed the question whether these metabolites differ in their biological impact on ageing and intraperitoneally injected 13-month-old C57BL/6JRj mice on an ad-libitum (AL) HFD with resveratrol, dihydroresveratrol or lunularin (24 mg/kg bodyweight; 3 times/week). Compared to mice injected with vehicle (AL-control), resveratrol and dihydroresveratrol did not change bodyweight and had no impact on insulin or glucose levels while lunularin slightly reduced feed intake and bodyweight gain. CR-mice showed lowered cholesterol, insulin and leptin levels, elevated adiponectin and phosphorylated AMPK levels in liver as well as increased transcription of Pck1 and Pgc1α when compared to the AL-control. In contrast, injections with the test substances did not change these parameters. We therefore conclude that in our model, resveratrol, lunularin and dihydroresveratrol did not act as CR mimetics.

Update on the human and mouse lipocalin (LCN) gene family, including evidence the mouse Mup cluster is result of an "evolutionary bloom"

Lipocalins (LCNs) are members of a family of evolutionarily conserved genes present in all kingdoms of life. There are 19 LCN-like genes in the human genome, and 45 Lcn-like genes in the mouse genome, which include 22 major urinary protein (Mup) genes. The Mup genes, plus 29 of 30 Mup-ps pseudogenes, are all located together on chromosome (Chr) 4; evidence points to an “evolutionary bloom” that resulted in this Mup cluster in mouse, syntenic to the human Chr 9q32 locus at which a single MUPP pseudogene is located. LCNs play important roles in physiological processes by binding and transporting small hydrophobic molecules —such as steroid hormones, odorants, retinoids, and lipids—in plasma and other body fluids. LCNs are extensively used in clinical practice as biochemical markers. LCN-like proteins (18–40 kDa) have the characteristic eight β-strands creating a barrel structure that houses the binding-site; LCNs are synthesized in the liver as well as various secretory tissues. In rodents, MUPs are involved in communication of information in urine-derived scent marks, serving as signatures of individual identity, or as kairomones (to elicit fear behavior). MUPs also participate in regulation of glucose and lipid metabolism via a mechanism not well understood. Although much has been learned about LCNs and MUPs in recent years, more research is necessary to allow better understanding of their physiological functions, as well as their involvement in clinical disorders.

Regulation of volatile and non-volatile pheromone attractants depends upon male social status

We investigated the regulation of chemical signals of house mice living in seminatural social conditions. We found that male mice more than doubled the excretion of major urinary proteins (MUPs) after they acquired a territory and become socially dominant. MUPs bind and stabilize the release of volatile pheromone ligands, and some MUPs exhibit pheromonal properties themselves. We conducted olfactory assays and found that female mice were more attracted to the scent of dominant than subordinate males when they were in estrus. Yet, when male status was controlled, females were not attracted to urine with high MUP concentration, despite being comparable to levels of dominant males. To determine which compounds influence female attraction, we conducted additional analyses and found that dominant males differentially upregulated the excretion of particular MUPs, including the pheromone MUP20 (darcin), and a volatile pheromone that influences female reproductive physiology and behavior. Our findings show that once male house mice become territorial and socially dominant, they upregulate the amount and types of excreted MUPs, which increases the intensities of volatiles and the attractiveness of their urinary scent to sexually receptive females.

Protein Restriction, Epigenetic Diet, Intermittent Fasting as New Approaches for Preventing Age-associated Diseases

Data from epidemiological and experimental studies have shown that diet and eating patterns have a major role in the pathogenesis of many age-associated diseases. Since 1935, calorie restriction (CR) has been identified as one of the most effective nongenetic dietary interventions that can increase lifespan. It involves reducing calorie intake by about 20%–40% below ad libitum, without malnutrition. Restricting food intake has been observed to increase lifespan and prevent many age-associated diseases in rats, mice, and many other species. Understanding the metabolic, molecular, and cellular mechanisms involved in the anti-aging effects of CR can help us to find dietary interventions that can mimic its effects. Recently, different studies have shown that intermittent fasting, protein restriction, and an epigenetic diet can have similar effects to those of CR. These approaches were selected because it has been indicated that they act through a similar molecular pathway and also, are safe and effective in delaying or preventing diseases. In this review, we focus on the mechanistic pathway involved in CR. Then, we review the mimicking interventions through the mechanistic approach. For this purpose, we reviewed both animal and human articles, mainly available through the PubMed online database. We then selected the most relevant full texts which are summarized in this article.

Calorie restriction effects on circadian rhythms in gene expression are sex dependent

The rhythms in the expression of circadian clock genes are affected by calorie restriction (CR), a dietary paradigm known to increase lifespan. Many physiological effects of CR differ between males and females; here we investigated if the sex of animals affects the CR induced changes in the circadian rhythms. The liver expression of some circadian clock genes such as Bmal1 and three Periods (Per1, Per2 and Per3) and the effect of CR on the expression of these genes were sex independent, while the expression of Rev-Erb alpha, Ror gamma and both Cryptochome (Cry1 and Cry2) genes was different between males and females. The effect of CR on Rev-Erb alpha, Ror gamma and Cry1 gene expression was sex dependent. The expression and the effects of CR were sex-specific for several genes previously reported to be regulated by CR: Fmo3, Mup4, Serpina12 and Cyp4a12, while the expression of Cyp4a14a was sex independent. IGF signaling plays an important role in aging and CR effects. Igf-1 expression is regulated by CR and by the circadian clock, we found that rhythms in Igf-1 expression have sexual dimorphism. Our data provide molecular evidence that the sex of animals is an important modulator of circadian rhythms in gene expression and their response to CR.

Chronic Co-species Housing Mice and Rats Increased the Competitiveness of Male Mice

Rats are predators of mice in nature. Nevertheless, it is a common practice to house mice and rats in a same room in some laboratories. In this study, we investigated the behavioral and physiological responsively of mice in long-term co-species housing conditions. Twenty-four male mice were randomly assigned to their original raising room (control) or a rat room (co-species-housed) for more than 6 weeks. In the open-field and light-dark box tests, the behaviors of the co-species-housed mice and controls were not different. In a 2-choice test of paired urine odors [rabbit urine (as a novel odor) vs. rat urine, cat urine (as a natural predator-scent) vs. rabbit urine, and cat urine vs. rat urine], the co-species-housed mice were more ready to investigate the rat urine odor compared with the controls and may have adapted to it. In an encounter test, the rat-room-exposed mice exhibited increased aggression levels, and their urines were more attractive to females. Correspondingly, the levels of major urinary proteins were increased in the co-species-housed mouse urine, along with some volatile pheromones. The serum testosterone levels were also enhanced in the co-species-housed mice, whereas the corticosterone levels were not different. The norepinephrine, dopamine, and 5-HT levels in the right hippocampus and striatum were not different between the 2. Our findings indicate that chronic co-species housing results in adaptation in male mice; furthermore, it appears that long-term rat-odor stimuli enhance the competitiveness of mice, which suggests that appropriate predator-odor stimuli may be important to the fitness of prey animals.

Diversity of major urinary proteins (MUPs) in wild house mice

Major urinary proteins (MUPs) are often suggested to be highly polymorphic, and thereby provide unique chemical signatures used for individual and genetic kin recognition; however, studies on MUP variability have been lacking. We surveyed populations of wild house mice (Mus musculus musculus), and examined variation of MUP genes and proteins. We sequenced several Mup genes (9 to 11 loci) and unexpectedly found no inter-individual variation. We also found that microsatellite markers inside the MUP cluster show remarkably low levels of allelic diversity, and significantly lower than the diversity of markers flanking the cluster or other markers in the genome. We found low individual variation in the number and types of MUP proteins using a shotgun proteomic approach, even among mice with variable MUP electrophoretic profiles. We identified gel bands and spots using high-resolution mass spectrometry and discovered that gel-based methods do not separate MUP proteins, and therefore do not provide measures of MUP diversity, as generally assumed. The low diversity and high homology of Mup genes are likely maintained by purifying selection and gene conversion, and our results indicate that the type of selection on MUPs and their adaptive functions need to be re-evaluated.

Regulation of highly homologous major urinary proteins in house mice quantified with label-free proteomic methods

Major urinary proteins (MUPs) are highly homologous proteoforms that function in binding, transporting and releasing pheromones in house mice. The main analytical challenge for studying variation in MUPs, even for state-of-the-art proteomics techniques, is their high degree of amino acid sequence homology. In this study we used unique peptides for proteoform-specific identification. We applied different search engines (ProteinPilot™vs. PEAKS®) and protein databases (MUP database vs. SwissProt + unreviewed MUPs), and found that proteoform identification is influenced by addressing background proteins (unregulated urinary proteins, non-MUPs) during the database search. High resolution Q-TOF mass spectrometry was used to identify and precisely quantify the regulation of MUP proteoforms in male mice that were reared in standard housing and then transferred to semi-natural enclosures (within-subject design). By using a designated MUP database we were able to distinguish 19 MUP proteoforms, with A2CEK6 (a Mup11 gene product) being the most abundant based on spectral intensities. We compared three different quantification strategies based on MS1- (from IDA and SWATH™ spectra) and MS2 (SWATH™) data, and the results of these methods were correlated. Furthermore, three data normalization methods were compared and we found that increased statistical significance of fold-changes can be achieved by normalization based on urinary protein concentrations. We show that male mice living in semi-natural enclosures significantly up-regulated some but not all MUPs (differential regulation), e.g., A2ANT6, a Mup6 gene product, was upregulated between 9-fold (MS1) and 13-fold (MS2) using the designated MUP database. Finally, we show that 85 ± 7% of total MS intensity can be attributed to MUP-derived peptides, which supports the assumption that MUPs are the primary proteins in mouse urine. Our results provide new tools for assessing qualitative and quantitative variation of MUPs and suggest that male mice regulate the expression of specific MUP proteoforms, depending upon social conditions.

The Presence Of Strange Males' Odor Induces Behavioral Responses And Elevated Levels Of Low Molecular Weight Proteins Excreted In The Urine Of Mature Water Vole Males (Arvicola amphibius L)

We hypothesized that low molecular weight urinary proteins play a role in male-male chemical communication in the water vole, Arvicola ampibius L. We studied the effect of placing soiled litter from strange males into the cage of another sexually mature male on the intensity of its digging and scattering, urination on the litter, and alteration in the levels of low molecular weight proteins (15-25 kDa) excreted in the urine before and after 4 days of exposure as determined by chip electrophoresis. The intensity of digging and scattering was positively correlated with levels of testosterone in serum of males exposed to strange male odors (r = 0.56; P < 0.01), as well as with the concentration of low molecular weight proteins in the donor's urine (r = 0.52, P < 0.05). At the end of the experiment, the level of low molecular weight protein in excreted urine was elevated in the males exposed to the strange male's litter. These results highlight the importance of quantitative inter-individual variation of low molecular weight urinary proteins in the modulation of the physiology and behavior of conspecifics.

Restriction on an energy-dense diet improves markers of metabolic health and cellular aging in mice through decreasing hepatic mTOR activity

Dietary restriction (DR) on a normal low-fat diet improves metabolic health and may prolong life span. However, it is still uncertain whether restriction of an energy-dense, high-fat diet would also be beneficial and mitigate age-related processes. In the present study, we determined biomarkers of metabolic health, energy metabolism, and cellular aging in obesity-prone mice subjected to 30% DR on a high-fat diet for 6 months. Dietary-restricted mice had significantly lower body weights, less adipose tissue, lower energy expenditure, and altered substrate oxidation compared to their ad libitum-fed counterparts. Hepatic major urinary proteins (Mup) expression, which is linked to glucose and energy metabolism, and biomarkers of metabolic health, including insulin, glucose, cholesterol, and leptin/adiponectin ratio, were likewise reduced in high-fat, dietary-restricted mice. Hallmarks of cellular senescence such as Lamp2a and Hsc70 that mediate chaperone-mediated autophagy were induced and mechanistic target of rapamycin (mTOR) signaling mitigated upon high-fat DR. In contrast to DR applied in low-fat diets, anti-oxidant gene expression, proteasome activity, as well as 5'-adenosine monophosphate-activated protein kinase (AMPK) activation were not changed, suggesting that high-fat DR may attenuate some processes associated with cellular aging without the induction of cellular stress response or energy deprivation.

Strategy for NMR metabolomic analysis of urine in mouse models of obesity--from sample collection to interpretation of acquired data

The mouse model of monosodium glutamate induced obesity was used to examine and consequently optimize the strategy for analysis of urine samples by NMR spectroscopy. A set of nineteen easily detectable metabolites typical in obesity-related studies was selected. The impact of urine collection protocol, choice of (1)H NMR pulse sequence, and finally the impact of the normalization method on the detected concentration of selected metabolites were investigated. We demonstrated the crucial effect of food intake and diurnal rhythms resulting in the choice of a 24-hour fasting collection protocol as the most convenient for tracking obesity-induced increased sensitivity to fasting. It was shown that the Carr-Purcell-Meiboom-Gill (CPMG) experiment is a better alternative to one-dimensional nuclear Overhauser enhancement spectroscopy (1D-NOESY) for NMR analysis of mouse urine due to its ability to filter undesirable signals of proteins naturally present in rodent urine. Normalization to total spectral area provided comparable outcomes as did normalization to creatinine or probabilistic quotient normalization in the CPMG-based model. The optimized approach was found to be beneficial mainly for low abundant metabolites rarely monitored due to their overlap by strong protein signals.

Major urinary protein (MUP) profiles show dynamic changes rather than individual 'barcode' signatures

House mice (Mus musculus) produce a variable number of major urinary proteins (MUPs), and studies suggest that each individual produces a unique MUP profile that provides a distinctive odor signature controlling individual and kin recognition. This 'barcode hypothesis' requires that MUP urinary profiles show high individual variability within populations and also high individual consistency over time, but tests of these assumptions are lacking. We analyzed urinary MUP profiles of 66 wild-caught house mice from eight populations using isoelectric focusing. We found that MUP profiles of wild male house mice are not individually unique, and though they were highly variable, closer inspection revealed that the variation strongly depended on MUP band type. The prominent ('major) bands were surprisingly homogenous (and hence most MUPs are not polymorphic), but we also found inconspicuous ('minor') bands that were highly variable and therefore potential candidates for individual fingerprints. We also examined changes in urinary MUP profiles of 58 males over time (from 6 to 24 weeks of age), and found that individual MUP profiles and MUP concentration were surprisingly dynamic, and showed significant changes after puberty and during adulthood. Contrary to what we expected, however, the minor bands were the most variable over time, thus no good candidates for individual fingerprints. Although MUP profiles do not provide individual fingerprints, we found that MUP profiles were more similar among siblings than non-kin despite considerable fluctuation. Our findings show that MUP profiles are not highly stable over time, they do not show strong individual clustering, and thus challenge the barcode hypothesis. Within-individual dynamics of MUP profiles indicate a different function of MUPs in individual recognition than previously assumed and advocate an alternative hypothesis ('dynamic changes' hypothesis).

Chemical signals in terrestrial vertebrates: search for design features

We review current information on intraspecific chemical signals and search for patterns in signal chemistry among modern terrestrial vertebrates (Amniota), including tortoises, squamate reptiles (amphisbaenians, lizards, and snakes), birds, and mammals.

Changes in gene expression associated with FTO overexpression in mice

Single nucleotide polymorphisms in the first intron of the fat-mass-and-obesity-related gene FTO are associated with increased body weight and adiposity. Increased expression of FTO is likely underlying this obesity phenotype, as mice with two additional copies of Fto (FTO-4 mice) exhibit increased adiposity and are hyperphagic. FTO is a demethylase of single stranded DNA and RNA, and one of its targets is the m6A modification in RNA, which might play a role in the regulation of gene expression. In this study, we aimed to examine the changes in gene expression that occur in FTO-4 mice in order to gain more insight into the underlying mechanisms by which FTO influences body weight and adiposity. Our results indicate an upregulation of anabolic pathways and a downregulation of catabolic pathways in FTO-4 mice. Interestingly, although genes involved in methylation were differentially regulated in skeletal muscle of FTO-4 mice, no effect of FTO overexpression on m6A methylation of total mRNA was detected.

Beneficial effects of a 6-month dietary restriction are time-dependently abolished within 2 weeks or 6 months of refeeding-genome-wide transcriptome analysis in mouse liver

Dietary restriction (DR) has been shown to exert a number of beneficial effects including the prolongation of life span. One of the mechanisms by which DR leads to these advantages seems to be the induction of endogenous antioxidant defense and stress response mechanisms. However, little is known about the persistence of DR benefits after return to an ad libitum diet. In this study, male C57BL/6 mice were fed 75% of a normal diet for 6 months (DR) followed by 6 months of ad libitum refeeding (RF) and compared to a continuously ad libitum fed control group. To study the impact of DR and RF on the liver transcriptome, a global gene expression profile was generated using microarray technology. In comparison, the DR group showed lower body weight, lower triglyceride and cholesterol levels, reduced lipid peroxidation, and a changed hepatic fatty acid pattern. mRNA transcription and activity of antioxidant and phase II enzymes, as well as metallothionein 1 gene expression, were increased and autophagy was induced. Shifting from long-term DR to RF abolished 96% of the DR-mediated changes in differential gene expression within 2 weeks, and after 6 months of refeeding all of the previously differentially expressed genes were similar in both groups. These results indicate that DR has to be maintained continuously to keep its beneficial effects.