Mouse genetics: Catalogue and scissors

Phenotypic analysis of gene-specific knockout (KO) mice has revolutionized our understanding of in vivo gene functions. As the use of mouse embryonic stem (ES) cells is inevitable for conventional gene targeting, the generation of knockout mice remains a very time-consuming and expensive process. To accelerate the large-scale production and phenotype analyses of KO mice, international efforts have organized global consortia such as the International Knockout Mouse Consortium (IKMC) and International Mouse Phenotype Consortium (IMPC), and they are persistently expanding the KO mouse catalogue that is publicly available for the researches studying specific genes of interests in vivo. However, new technologies, adopting zinc-finger nucleases (ZFNs) or Transcription Activator-like Effector (TALE) Nucleases (TALENs) to edit the mouse genome, are now emerging as valuable and effective shortcuts alternative for the conventional gene targeting using ES cells. Here, we introduce the recent achievement of IKMC, and evaluate the significance of ZFN/TALEN technology in mouse genetics. [BMB Reports 2012; 45(12): 686-692]

Resistance exercise training-induced skeletal muscle strength provides protective effects on high-fat-diet-induced metabolic stress in mice

Background Resistance exercise training is known to improve metabolic disorders, such as obesity and type2 diabetes. In this study, we investigated whether the beneficial effects of resistance exercise training persisted even after the discontinuation of training with high-fat diet (HFD)-induced metabolic stress. We further evaluated whether the improvement in skeletal muscle strength and endurance by training were correlated with improved metabolism. Eight-week-old male C57BL/6N mice were divided into groups that remained sedentary or had access to daily resistance exercise via ladder climbing for 8 weeks. Trained and untrained mice were fed an HFD for 1 week after the exercise training intervention (n = 5–8 per group). Results Resistance exercise-trained mice had a lean phenotype and counteracted diet-induced obesity and glucose tolerance, even after exercise cessation. Grip strength was significantly inversely correlated with the body weight, fat mass, and glucose tolerance. However, hanging time was significantly inversely correlated with body weight only. Conclusions These results have strong implications for the preventive effect of resistance exercise-induced metabolic improvement by enhancing skeletal muscle strength rather than endurance.This work was supported by the Korea Mouse Phenotyping Project (NRF-2013M3A9D5072550) of the Ministry of Science, and ICT, through the National Research Foundation

Notch1 binds and induces degradation of Snail in hepatocellular carcinoma

<p>Abstract</p> <p>Background</p> <p>Hepatocellular carcinoma (HCC) is a common, highly invasive malignant tumor associated with a high mortality rate. We previously reported that the aberrant expression of Snail via activation of reactive oxygen species contributes to the invasive property of HCC, in part by downregulation of E-cadherin through both transcriptional repression and epigenetic modification of the E-cadherin promoter. Having demonstrated the ability of Snail to bind and recruit histone deacetylase 1 and DNA methyltransferase 1 in this context, we set out to look for other interactions that could affect its ability to promote oncogenic transformation and cancer cell invasion.</p> <p>Results</p> <p>Using cells that stably expressed Snail, we characterized Snail protein interactors by tandem affinity purification and mass spectrometry. Immunoprecipitation and subcellular colocalization studies were performed to confirm our identification of the Notch1 intracellular domain (NICD) as a novel Snail-binding partner. NICD interaction with Snail was found to induce ubiquitination and MDM2-dependent degradation of Snail. Interestingly, NICD inhibited Snail-dependent invasive properties in both HCC cells and mouse embryonic fibroblasts.</p> <p>Conclusions</p> <p>Our study demonstrates that NICD can oppose Snail-dependent HCC cell invasion by binding and inducing proteolytic degradation of Snail. Although Notch signaling and Snail are both widely considered tumor-promoting factors, our findings indicate that the individual oncogenic contribution of Notch1 and Snail in malignant systems should be interpreted carefully, particularly when they are conjointly expressed.</p

Evaluation of factors related to Anaesthesia-induced Lens opacity in experimental mice

To investigate conditions that cause temporal lens opacity, we tested chemical and physical factors, such as anaesthesia dose, ocular surface dryness, and infrared (IR) light exposure in anaesthetised C57BL/6 N mice. Mice were anaesthetised with a low (80%; tiletamine/zolazepam 32 mg/kg and xylazine 8 mg/kg, intraperitoneal injection) or high (120%; 48 mg/kg and 12 mg/kg) dose of anaesthetic and examined every 5 min from 10 to 30 min after anaesthesia was induced. Lens opacity levels were assessed and graded (1–6) using the standard classification system. Regardless of the anaesthetic dose, lens opacity grade was 1–2 in moisturised eyes with application of 0.5% carboxymethylcellulose, and 5–6 in dry ocular surface conditions. Lens opacity in mice with high-dose anaesthetic in the dry ocular surface condition was not different from that of mice with low-dose anaesthetic. Lens opacity grade 1–2 was noted in eyes in the wet ocular surface condition, regardless of IR light exposure. During IR light exposure in eyes in the dry ocular surface condition, lens opacity (grade 6) in mice with high-dose anaesthetic was not different from that (grade 6) in mice with low-dose anaesthetic. We demonstrated that ocular surface dryness might be a relevant factor for the formation and progression of lens opacity in anesthetized C57BL/6 N mice. Anaesthesia dose and IR light exposure did not strongly influence lens opacity formation. Furthermore, eyes with corneal dryness-induced lens opacity recovered to normal status without additional intervention.This research was supported by Korea Mouse Phenotyping Project (NRF2013M3A9D5072551) of the Ministry of Science and ICT through the National Research Foundation

The effects of wearing KF94 masks on cardiorespiratory function and hemorheological response during moderate intensity exercise in adult males

The purpose of this study was to examine the effect of wearing a Korea filter 94 (KF94) mask on cardiorespiratory function and hemorheological responses during moderate intensity exercise in men during the Coronavirus disease 2019 (COVID-19) pandemic. 12 healthy males aged 20 to 29 years (28.3 ± 3.6 yr) were recruited for this study. The exercise intensity corresponding to the anaerobic threshold level was determined following a maximum graded exercise test, and exercise was performed for 40 minutes with a cycle ergometer at the target exercise intensity. Cardiorespiratory function, blood pressure, and hemorheological responses were measured every 10 minutes at rest and during exercise. Our results indicated no differences between conditions in respiratory frequency (Rf), tidal volume (TV), minute ventilation (VE), carbon dioxide production (V̇CO2), and partial pressure of arterial oxygen (PaO2). However, oxygen consumption (V̇O2) was significantly lower in the KF94 mask group compared to the control. There were no differences in systolic blood pressure (SBP), diastolic blood pressure (DBP), rate pressure product (RPP), aggregation index (AI), and blood critical stress (BCS) between the two groups. The mask group had a significant respiratory exchange ratio (R) at rest and during 10 minutes exercise compared to the control. The elongation index was higher at rest, 10 minutes, and 30 minutes in the mask group than control group (p < 0.05). Overall, our results suggest that although V̇O2 was decreased and R values were increased, the effects of other physiological parameters and hemorheological responses imposed by face masks during moderate intensity exercise are small. Thus, although negative effects of using face masks affect exercise capacity (i.e., exercise tolerance), our findings suggest that individuals wearing KF94 could safely exercise and get some health benefits from physical activities during the COVID-19 pandemic

Adult Hippocampal Neurogenesis Can Be Enhanced by Cold Challenge Independently From Beigeing Effects

In this study, we investigated the effects of cold challenge on adult hippocampal neurogenesis (AHN) and hippocampal gene expression and whether these are mediated by beigeing of peripheral fat tissues. Cold challenge (6 ± 2°C) for 1 and 4 weeks was found to induce beigeing effects in inguinal white adipose tissue based on hematoxylin and eosin staining as well as uncoupled protein-1 immunohistochemical staining. In the hippocampus, cold challenge for 1 or 4 weeks increased dentate gyrus neurogenesis and expression of genes related to AHN, including notch signaling, G protein-coupled receptor signaling, and adrenergic beta receptor-1. However, this enhancement of neurogenesis and gene expression by cold challenge was not shown by administration of CL 316,243, which induces peripheral beigeing similar to cold challenge but does not cross the blood–brain barrier. These results suggest that cold challenge promotes AHN and central expression of AHN-related, signaling, and β1-adrenergic receptors genes, and that peripheral beigeing by itself is not sufficient to mediate these effects. Considering the increase in AHN and gene expression changes, cold challenge may offer a novel approach to hippocampal modulation

Gut taste receptor type 1 member 3 is an intrinsic regulator of Western diet-induced intestinal inflammation

Background Long-term intake of a Western diet (WD), characterized by a high-fat content and sugary drinks, is hypothesized to contribute to the development of inflammatory bowel disease (IBD). Despite the identified clinical association, the molecular mechanisms by which dietary changes contribute to IBD development remain unknown. Therefore, we examined the influence of long-term intake of a WD on intestinal inflammation and the mechanisms by which WD intake affects IBD development. Methods Mice fed normal diet or WD for 10weeks, and bowel inflammation was evaluated through pathohistological and infiltrated inflammatory cell assessments. To understand the role of intestinal taste receptor type 1 member 3 (TAS1R3) in WD-induced intestinal inflammation, cultured enteroendocrine cells harboring TAS1R3, subjected to RNA interference or antagonist treatment, and Tas1r3-deficient mice were used. RNA-sequencing, flow cytometry, 16S metagenomic sequencing, and bioinformatics analyses were performed to examine the involved mechanisms. To demonstrate their clinical relevance, intestinal biopsies from patients with IBD and mice with dextran sulfate sodium-induced colitis were analyzed. Results Our study revealed for the first time that intestinal TAS1R3 is a critical mediator of WD-induced intestinal inflammation. WD-fed mice showed marked TAS1R3 overexpression with hallmarks of serious bowel inflammation. Conversely, mice lacking TAS1R3 failed to exhibit inflammatory responses to WD. Mechanistically, intestinal transcriptome analysis revealed that Tas1r3 deficiency suppressed mTOR signaling, significantly increasing the expression of PPARγ (a major mucosal defense enhancer) and upregulating the expression of PPARγ target-gene (tight junction protein and antimicrobial peptide). The gut microbiota of Tas1r3-deficient mice showed expansion of butyrate-producing Clostridia. Moreover, an increased expression of host PPARγ-signaling pathway proteins was positively correlated with butyrate-producing microbes, suggesting that intestinal TAS1R3 regulates the relationship between host metabolism and gut microflora in response to dietary factors. In cultured intestinal cells, regulation of the TAS1R3–mTOR–PPARγ axis was critical for triggering an inflammatory response via proinflammatory cytokine production and secretion. Abnormal regulation of the axis was observed in patients with IBD. Conclusions Our findings suggest that the TAS1R3–mTOR–PPARγ axis in the gut links Western diet consumption with intestinal inflammation and is a potential therapeutic target for IBD.This work was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education (Grant NRF-2021R1A2C3010280), and the Korea Mouse Phenotyping Project through the National Research Foundation of Korea funded by the Ministry of Science and ICT (Grant NRF-2013M3A9D5072550). The funding sources had no role in the design of the study, in the collection, analysis, and interpretation of data, or in the writing of the manuscrip