Functional study of the ST6GAL2 gene regulating skeletal muscle growth and development.

ST6GAL2, a member of the sialoglycosyltransferase family, primarily localizes within the cellular Golgi apparatus. However, the role of the ST6GAL2 gene in skeletal muscle growth and development remains elusive. In this study, the impact of the ST6GAL2 gene on the proliferation, differentiation, and apoptosis of primary chicken myoblasts at the cellular level was investigated. Quantitative fluorescent PCR was used to measure the expression levels of genes. Subsequently, using gene knockout mice, we assessed its effects on skeletal muscle growth and development in vivo. Our findings reveal that the ST6GAL2 gene promotes the expression of cell cycle and proliferation-related genes, including CCNB2 and PCNA, and apoptosis-related genes, such as Fas and Caspase-9. At the individual level, double knockout of ST6GAL2 inhibited the formation of both fast and slow muscle fibers in the quadriceps, extensor digitorum longus, and tibial anterior muscle, while promoting their formation in the gastrocnemius and soleus. These results collectively demonstrate that the ST6GAL2 gene facilitates the proliferation, apoptosis, and fusion processes of primary chicken myoblasts. Additionally, it promotes the enlargement of cross-sectional muscle fiber areas and regulates the formation of fast and slow muscle fibers at the individual level, albeit inhibiting muscle fusion. This study provides valuable insights into the role of the ST6GAL2 gene in promoting proliferation of skeletal muscle.

The stability of FKBP9 maintained by BiP is crucial for glioma progression.

FK506-binding protein 9 (FKBP9) is involved in tumor malignancy by resistance to endoplasmic reticulum (ER) stress, and the up-regulation of FKBP9 is associated with patients' poor prognosis. The current knowledge of the molecular mechanisms is still limited. One previous study showed that FKBP9 could confer glioblastoma cell resistance to ER stress through ASK1-p38 signaling. However, the upstream regulatory mechanism of FKBP9 expression is still indistinct. In this study, we identified the FKBP9 binding proteins using co-immunoprecipitation followed by mass spectrometry. Results showed that FKBP9 interacted with the binding immunoglobulin protein (BiP). BiP bound directly to FKBP9 with high affinity. BiP prolonged the half-life of the FKBP9 protein and stabilized the FKBP9 protein. BiP and FKBP9 protein levels were positively correlated in patients with glioma, and patients with high expression of BiP and FKBP9 showed a worse prognosis. Further studies showed that FKBP9 knockout in genetically engineered mice inhibited intracranial glioblastoma formation and prolonged survival by decreasing cellular proliferation and ER stress-induced CHOP-related apoptosis. Moreover, normal cells may depend less on FKBP9, as shown by the absence of apoptosis upon FKBP9 knockdown in a non-transformed human cell line and overall normal development in homozygous knockout mice. These findings suggest an important role of BiP-regulated FKBP9-associated signaling in glioma progression and the BiP-FKBP9 axis may be a potential therapeutic target for glioma.

SRSF2 is essential for maintaining pancreatic beta-cell identity and regulating glucose homeostasis in mice.

Diabetes is characterized by decreased beta-cell mass and islet dysfunction. The splicing factor SRSF2 plays a crucial role in cell survival, yet its impact on pancreatic beta cell survival and glucose homeostasis remains unclear. We observed that the deletion of Srsf2 specifically in beta cells led to time-dependent deterioration in glucose tolerance, impaired insulin secretion, decreased islet mass, an increased number of alpha cells, and the onset of diabetes by the age of 10 months in mice. Single-cell RNA sequencing (scRNA-seq) analyses revealed that, despite an increase in populations of unfolded protein response (UPR)-activated and undifferentiated beta cells within the SRSF2_KO group, there was a notable decrease in the expression of UPR-related and endoplasmic reticulum (ER)-related genes, accompanied by a loss of beta-cell identity. This suggests that beta cells have transitioned from an adaptive phase to a maladaptive phase in islets of 10-month-old SRSF2_KO mice. Further results demonstrated that deletion of SRSF2 caused decreased proliferation in beta cells within 3-month-old islets and Min6 cells. These findings underscore the essential role of SRSF2 in controlling beta-cell proliferation and preserving beta-cell function in mice.

MYCBPAP is a central apparatus protein required for centrosome-nuclear envelope docking and sperm tail biogenesis in mice.

The structure of the sperm flagellar axoneme is highly conserved across species and serves the essential function of generating motility to facilitate the meeting of spermatozoa with the egg. During spermiogenesis, the axoneme elongates from the centrosome, and subsequently the centrosome docks onto the nuclear envelope to continue tail biogenesis. Mycbpap is expressed predominantly in mouse and human testes and conserved in Chlamydomonas as FAP147. A previous cryo-electron microscopy analysis has revealed the localization of FAP147 to the central apparatus of the axoneme. Here, we generated Mycbpap-knockout mice and demonstrated the essential role of Mycbpap in male fertility. Deletion of Mycbpap led to disrupted centrosome-nuclear envelope docking and abnormal flagellar biogenesis. Furthermore, we generated transgenic mice with tagged MYCBPAP, which restored the fertility of Mycbpap-knockout males. Interactome analyses of MYCBPAP using Mycbpap transgenic mice unveiled binding partners of MYCBPAP including central apparatus proteins, such as CFAP65 and CFAP70, which constitute the C2a projection, and centrosome-associated proteins, such as CCP110. These findings provide insights into a MYCBPAP-dependent regulation of the centrosome-nuclear envelope docking and sperm tail biogenesis.

Beneficial effects of miR-132/212 deficiency in the zQ175 mouse model of Huntington's disease.

Huntington's disease (HD) is a rare genetic neurodegenerative disorder caused by an expansion of CAG repeats in the Huntingtin (HTT) gene. One hypothesis suggests that the mutant HTT gene contributes to HD neuropathology through transcriptional dysregulation involving microRNAs (miRNAs). In particular, the miR-132/212 cluster is strongly diminished in the HD brain. This study explores the effects of miR-132/212 deficiency specifically in adult HD zQ175 mice. The absence of miR-132/212 did not impact body weight, body temperature, or survival rates. Surprisingly, miR-132/212 loss seemed to alleviate, in part, the effects on endogenous Htt expression, HTT inclusions, and neuronal integrity in HD zQ175 mice. Additionally, miR-132/212 depletion led to age-dependent improvements in certain motor functions. Transcriptomic analysis revealed alterations in HD-related networks in WT- and HD zQ175-miR-132/212-deficient mice, including significant overlap in BDNF and Creb1 signaling pathways. Interestingly, however, a higher number of miR-132/212 gene targets was observed in HD zQ175 mice lacking the miR-132/212 cluster, especially in the striatum. These findings suggest a nuanced interplay between miR-132/212 expression and HD pathogenesis, providing potential insights into therapeutic interventions. Further investigation is needed to fully understand the underlying mechanisms and therapeutic potential of modulating miR-132/212 expression during HD progression.

Deficiency of Trps1 in Cementoblasts Impairs Cementogenesis and Tooth Root Formation.

Cementum is the least studied of all mineralized tissues and little is known about mechanisms regulating its formation. Therefore, the goal of this study was to provide new insights into the transcriptional regulation of cementum formation by determining the consequences of the deficiency of the Trps1 transcription factor in cementoblasts. We used Trps1Col1a1 cKO (2.3Co1a1-CreERT2;Trps1fl/fl) mice, in which Trps1 is deleted in cementoblasts. Micro-computed tomography analyses of molars of 4-week-old males and females demonstrated significantly shorter roots with thinner mineralized tissues (root dentin and cementum) in Trps1Col1a1 cKO compared to WT mice. Semi-quantitative histological analyses revealed a significantly reduced area of cellular cementum and localized deficiencies of acellular cementum in Trps1Col1a1 cKO mice. Immunohistochemical analyses revealed clustering of cementoblasts at the apex of roots, and intermittent absence of cementoblasts on Trps1Col1a1 cKO cementum surfaces. Fewer Osterix-positive cells adjacent to cellular cementum were also detected in Trps1Col1a1 cKO compared to WT mice. Decreased levels of tissue-nonspecific alkaline phosphatase (TNAP), an enzyme required for proper cementogenesis, were apparent in cementum, periodontal ligament, and alveolar bone of Trps1Col1a1 cKO. There were no apparent differences in levels of bone sialoprotein (Bsp) in cementum. Quantitative analyses of picrosirius red-stained periodontal ligament revealed shorter and disorganized collagen fibers in Trps1Col1a1 cKO mice demonstrating impaired periodontal structure. In conclusion, this study has identified Trps1 transcription factor as one of the important regulators of cellular and acellular cementum formation. Furthermore, this study suggests that Trps1 supports the function of cementoblasts by upregulating expression of the major proteins required for cementogenesis, such as Osterix and TNAP.

Brain Region-Specific Expression Levels of Synuclein Genes in an Acid Sphingomyelinase Knockout Mouse Model: Correlation with Depression-/Anxiety-Like Behavior and Locomotor Activity in the Absence of Genotypic Variation.

Accumulating evidence suggests an involvement of sphingolipids, vital components of cell membranes and regulators of cellular processes, in the pathophysiology of both Parkinson's disease and major depressive disorder, indicating a potential common pathway in these neuropsychiatric conditions. Based on this interaction of sphingolipids and synuclein proteins, we explored the gene expression patterns of α-, ß-, and γ-synuclein in a knockout mouse model deficient for acid sphingomyelinase (ASM), an enzyme catalyzing the hydrolysis of sphingomyelin to ceramide, and studied associations with behavioral parameters. Normalized Snca, Sncb, and Sncg gene expression was determined by quantitative PCR in twelve brain regions of sex-mixed homozygous (ASM-/-, n = 7) and heterozygous (ASM+/-, n = 7) ASM-deficient mice, along with wild-type controls (ASM+/+, n = 5). The expression of all three synuclein genes was brain region-specific but independent of ASM genotype, with ß-synuclein showing overall higher levels and the least variation. Moreover, we discovered correlations of gene expression levels between brain regions and depression- and anxiety-like behavior and locomotor activity, such as a positive association between Snca mRNA levels and locomotion. Our results suggest that the analysis of synuclein genes could be valuable in identifying biomarkers and comprehending the common pathological mechanisms underlying various neuropsychiatric disorders.

VPAC1 and VPAC2 receptors mediate tactile hindpaw hypersensitivity and carotid artery dilatation induced by PACAP38 in a migraine relevant mouse model.

BACKGROUND: Pituitary adenylate cyclase-activating peptide (PACAP) is a neuropeptide pivotal in migraine pathophysiology and is considered a promising new migraine drug target. Although intravenous PACAP triggers migraine attacks and a recent phase II trial with a PACAP-inhibiting antibody showed efficacy in migraine prevention, targeting the PACAP receptor PAC1 alone has been unsuccessful. The present study investigated the role of three PACAP receptors (PAC1, VPAC1 and VPAC2) in inducing migraine-relevant hypersensitivity in mice. METHODS: Hindpaw hypersensitivity was induced by repeated PACAP38 injections. Tactile sensitivity responses were quantified using von Frey filaments in three knockout (KO) mouse strains, each lacking one of the PACAP-receptors (Ntotal = 160). Additionally, ex vivo wire myography was used to assess vasoactivity of the carotid artery, and gene expression of PACAP receptors was examined by qPCR. RESULTS: PACAP38 induced hypersensitivity in WT controls (p < 0.01) that was diminished in VPAC1 and VPAC2 KO mice (p < 0.05). In contrast, PAC1 KO mice showed similar responses to WT controls (p > 0.05). Myograph experiments supported these findings showing diminished vasoactivity in VPAC1 and VPAC2 KO mice. We found no upregulation of the non-modified PACAP receptors in KO mice. CONCLUSIONS: This study assessed all three PACAP receptors in a migraine mouse model and suggests a significant role of VPAC receptors in migraine pathophysiology. The lack of hypersensitivity reduction in PAC1 KO mice suggests the involvement of other PACAP receptors or compensatory mechanisms. The results indicate that targeting only individual PACAP receptors may not be an effective migraine treatment.

Experience-dependent grooming microstructure alterations and gastrointestinal dysfunction in the SAPAP3 knockout mouse model of compulsive behaviour.

BACKGROUND: Compulsive- and anxiety-like behaviour can be efficiently modelled in SAPAP3 knockout (KO) mice, a preclinical model of relevance to obsessive-compulsive disorder (OCD). Although there is emerging evidence in the clinical literature of gastrointestinal dysfunction in OCD, no previous studies have investigated gut function in preclinical models of relevance to OCD. Similarly, the effects of voluntary exercise (EX) or environmental enrichment (EE) have not yet been explored in this context. METHOD: We comprehensively phenotyped the SAPAP3 KO mouse model, including the assessment of grooming microstructure, anxiety- and depressive-like behaviour, and gastrointestinal function. Mice were exposed to either standard housing (SH), exercise (EX, provided by giving mice access to running wheels), or environmental enrichment (EE) for 4 weeks to investigate the effects of enriched housing conditions in this animal model relevant to OCD. FINDINGS: Our study is the first to assess grooming microstructure, perseverative locomotor activity, and gastrointestinal function in SAPAP3 KO mice. We are also the first to report a sexually dimorphic effect of grooming in young-adult SAPAP3 KO mice; along with changes to grooming patterning and indicators of gut dysfunction, which occurred in the absence of gut dysbiosis in this model. Overall, we found no beneficial effects of voluntary exercise or environmental enrichment interventions in this mouse model; and unexpectedly, we revealed a deleterious effect of wheel-running exercise on grooming behaviour. We suspect that the detrimental effects of experimental housing in our study may be indicative of off-target effects of stress-a conclusion that warrants further investigation into the effects of chronic stress in this preclinical model of compulsive behaviour.

ZMYND12 serves as an IDAd subunit that is essential for sperm motility in mice.

Inner dynein arms (IDAs) are formed from a protein complex that is essential for appropriate flagellar bending and beating. IDA defects have previously been linked to the incidence of asthenozoospermia (AZS) and male infertility. The testes-enriched ZMYND12 protein is homologous with an IDA component identified in Chlamydomonas. ZMYND12 deficiency has previously been tied to infertility in males, yet the underlying mechanism remains uncertain. Here, a CRISPR/Cas9 approach was employed to generate Zmynd12 knockout (Zmynd12-/-) mice. These Zmynd12-/- mice exhibited significant male subfertility, reduced sperm motile velocity, and impaired capacitation. Through a combination of co-immunoprecipitation and mass spectrometry, ZMYND12 was found to interact with TTC29 and PRKACA. Decreases in the levels of PRKACA were evident in the sperm of these Zmynd12-/- mice, suggesting that this change may account for the observed drop in male fertility. Moreover, in a cohort of patients with AZS, one patient carrying a ZMYND12 variant was identified, expanding the known AZS-related variant spectrum. Together, these findings demonstrate that ZMYND12 is essential for flagellar beating, capacitation, and male fertility.

Development of functional spermatozoa in mammalian spermiogenesis.

Infertility is a global health problem affecting one in six couples, with 50% of cases attributed to male infertility. Spermatozoa are male gametes, specialized cells that can be divided into two parts: the head and the flagellum. The head contains a vesicle called the acrosome that undergoes exocytosis and the flagellum is a motility apparatus that propels the spermatozoa forward and can be divided into two components, axonemes and accessory structures. For spermatozoa to fertilize oocytes, the acrosome and flagellum must be formed correctly. In this Review, we describe comprehensively how functional spermatozoa develop in mammals during spermiogenesis, including the formation of acrosomes, axonemes and accessory structures by focusing on analyses of mouse models.

MicroRNA-26a deficiency attenuates the severity of frozen shoulder in a mouse immobilization model.

The main pathogenesis of the frozen shoulder is thought to be the inflammation of the intra-articular synovium and subsequent fibrosis of the shoulder joint capsule. However, the molecular pathogenesis of the frozen shoulder is still unknown. A class of noncoding RNAs, microRNAs contribute to various diseases including musculoskeletal diseases. MicroRNA-26a (miR-26a) has been reported to be associated with fibrosis in several organs. This study aims to reveal the role of miR-26a on fibrosis in the shoulder capsule using a frozen shoulder model in miR-26a deficient (miR-26a KO) mice. MiR-26a KO and wild-type (WT) mice were investigated using a frozen shoulder model. The range of motion (ROM) of the shoulder, histopathological changes such as synovitis, and fibrosis-related gene expression in the model mice were evaluated to determine the role of miR-26a. In WT mice, both inflammatory cell infiltration and thickening of the inferior shoulder joint capsule were observed after 1 week of immobilization, and this thickening further progressed over the subsequent 6 weeks. However, the immobilized shoulder in miR-26a KO mice consistently exhibited significantly better ROM compared with WT mice at 1 and 6 weeks, and histological changes were significantly less severe. The expression of inflammation- and fibrosis-related genes was decreased in the miR-26a KO mice compared with WT mice at 1 and 6 weeks. Together, miR-26a deficiency attenuated the severity of frozen shoulder in the immobilization model mouse. The present study suggests that miR-26a has the potential to be a target miRNA for therapeutic approach to frozen shoulder.

The Influence of BMP6 on Serotonin and Glucose Metabolism.

Previous studies have suggested a potential role of bone morphogenetic protein 6 (BMP6) in glucose metabolism, which also seems to be regulated by serotonin (5-hydroxytryptamine, 5HT), a biogenic amine with multiple roles in the organism. In this study, we explored possible interactions between BMP6, serotonin, and glucose metabolism regulation. The effect of BMP6 or 5HT on pancreatic ß-cells has been studied in vitro using the INS-1 832/13 rat insulinoma cell line. Studies in vivo have been performed on mice with the global deletion of the Bmp6 gene (BMP6-/-) and included glucose and insulin tolerance tests, gene expression studies using RT-PCR, immunohistochemistry, and ELISA analyses. We have shown that BMP6 and 5HT treatments have the opposite effect on insulin secretion from INS-1 cells. The effect of BMP6 on the 5HT system in vivo depends on the tissue studied, with no observable systemic effect on peripheral 5HT metabolism. BMP6 deficiency does not cause diabetic changes, although a mild difference in insulin tolerance test between BMP6-/- and WT mice was observed. In conclusion, BMP6 does not directly influence glucose metabolism, but there is a possibility that its deletion causes slowly developing changes in glucose and serotonin metabolism, which would become more expressed with ageing.

Reduced vacuolar ATPase protects mice from Friend virus infection - an unintended but instructive effect in Hif-2afl mice.

During acute viral infections, innate immune cells invade inflamed tissues and face hypoxic areas. Hypoxia-inducible factors (HIFs) adapt cellular responses towards these conditions. We wanted to investigate the effects of a loss of HIF-2α in macrophages during acute Friend murine leukemia retrovirus (FV) infection in C57BL/6 mice using a Cre/loxP system. Remarkably, mice with floxed Hif-2a (Hif-2afl; Hif-2a is also known as Epas1) did not show any signs of FV infection independent of Cre activity. This prevented a detailed analysis of the role of macrophage HIF-2α for FV infection but allowed us to study a model of unexpected FV resistance. Hif-2afl mice showed a significant decrease in the expression of the Atp6v1e2 gene encoding for the E2 subunit of the vacuolar H+-ATPase, which resulted in a decreased acidification of lysosomes and limited virus entry into the cell. These findings highlight that the insertion of loxP sites is not always without functional consequences and has established a phenotype in the floxed Hif-2a mouse, which is not only unexpected, but unwanted and is of relevance for the use of this mouse strain in (at least virus) experiments.

KCNQ1 is an essential mediator of the sex-dependent perception of moderate cold temperatures.

Low temperatures and cooling agents like menthol induce cold sensation by activating the peripheral cold receptors TRPM8 and TRPA1, cation channels belonging to the TRP channel family, while the reduction of potassium currents provides an additional and/or synergistic mechanism of cold sensation. Despite extensive studies over the past decades to identify the molecular receptors that mediate thermosensation, cold sensation is still not fully understood and many cold-sensitive peripheral neurons do not express the well-established cold sensor TRPM8. We found that the voltage-gated potassium channel KCNQ1 (Kv7.1), which is defective in cardiac LQT1 syndrome, is, in addition to its known function in the heart, a highly relevant and sex-specific sensor of moderately cold temperatures. We found that KCNQ1 is expressed in skin and dorsal root ganglion neurons, is sensitive to menthol and cooling agents, and is highly sensitive to moderately cold temperatures, in a temperature range at which TRPM8 is not thermosensitive. C-fiber recordings from KCNQ1-/- mice displayed altered action potential firing properties. Strikingly, only male KCNQ1-/- mice showed substantial deficits in cold avoidance at moderately cold temperatures, with a strength of the phenotype similar to that observed in TRPM8-/- animals. While sex-dependent differences in thermal sensitivity have been well documented in humans and mice, KCNQ1 is the first gene reported to play a role in sex-specific temperature sensation. Moreover, we propose that KCNQ1, together with TRPM8, is a key instrumentalist that orchestrates the range and intensity of cold sensation.

Acid ceramidase expression reduces IFNγ secretion by mouse CD4+ T cells and is crucial for maintaining B-cell numbers in mice.

Acid ceramidase (Ac) is a lysosomal enzyme catalyzing the generation of sphingosine from ceramide, and Ac inhibitors are currently being investigated as potential cancer therapeutics. Yet, the role of the Ac in immune responses, particularly anti-viral immunity, is not fully understood. To investigate the impact of Ac expression on various leukocyte populations, we generated a tamoxifen-inducible global knockout mouse model for the Ac (iAc-KO). Following tamoxifen administration to healthy mice, we extracted primary and secondary lymphoid organs from iAc-KO and wild-type (wt) littermates and subsequently performed extensive flow cytometric marker analysis. In addition, we isolated CD4+ T cells from the spleen and lymph nodes for sphingolipid profiling and restimulated them in vitro with Dynabeads™ Mouse T-activator CD3/CD28. Intracellular cytokine expression (FACS staining) was analyzed and secreted cytokines detected in supernatants. To study cell-intrinsic effects, we established an in vitro model for iAc-KO in isolated CD4+ T and B cells. For CD4+ T cells of iAc-KO versus wt mice, we observed reduced Ac activity, an increased ceramide level, and enhanced secretion of IFNγ upon CD3/CD28 costimulation. Moreover, there was a marked reduction in B cell and plasma cell and blast numbers in iAc-KO compared to wt mice. To study cell-intrinsic effects and in line with the 3R principles, we established in vitro cell culture systems for iAc-KO in isolated B and CD4+ T cells. Our findings pinpoint to a key role of the Ac in mature B and antibody-secreting cells and in IFNγ secretion by CD4+ T cells.

Downregulation of the metalloproteinases ADAM10 or ADAM17 promotes osteoclast differentiation.

Bone resorption is driven through osteoclast differentiation by macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-Β ligand (RANKL). We noted that a disintegrin and metalloproteinase (ADAM) 10 and ADAM17 are downregulated at the expression level during osteoclast differentiation of the murine monocytic cell line RAW264.7 in response to RANKL. Both proteinases are well known to shed a variety of single-pass transmembrane molecules from the cell surface. We further showed that inhibitors of ADAM10 or ADAM17 promote osteoclastic differentiation and furthermore enhance the surface expression of receptors for RANKL and M-CSF on RAW264.7 cells. Using murine bone marrow-derived monocytic cells (BMDMCs), we demonstrated that a genetic deficiency of ADAM17 or its required regulator iRhom2 leads to increased osteoclast development in response to M-CSF and RANKL stimulation. Moreover, ADAM17-deficient osteoclast precursor cells express increased levels of the receptors for RANKL and M-CSF. Thus, ADAM17 negatively regulates osteoclast differentiation, most likely through shedding of these receptors. To assess the time-dependent contribution of ADAM10, we blocked this proteinase by adding a specific inhibitor on day 0 of BMDMC stimulation with M-CSF or on day 7 of subsequent stimulation with RANKL. Only ADAM10 inhibition beginning on day 7 increased the size of developing osteoclasts indicating that ADAM10 suppresses osteoclast differentiation at a later stage. Finally, we could confirm our findings in human peripheral blood mononuclear cells (PBMCs). Thus, downregulation of either ADAM10 or ADAM17 during osteoclast differentiation may represent a novel regulatory mechanism to enhance their differentiation process. Enhanced bone resorption is a critical issue in osteoporosis and is driven through osteoclast differentiation by specific osteogenic mediators. The present study demonstrated that the metalloproteinases ADAM17 and ADAM10 critically suppress osteoclast development. This was observed for a murine cell line, for isolated murine bone marrow cells and for human blood cells by either preferential inhibition of the proteinases or by gene knockout. As a possible mechanism, we studied the surface expression of critical receptors for osteogenic mediators on developing osteoclasts. Our findings revealed that the suppressive effects of ADAM17 and ADAM10 on osteoclastogenesis can be explained in part by the proteolytic cleavage of surface receptors by ADAM10 and ADAM17, which reduces the sensitivity of these cells to osteogenic mediators. We also observed that osteoclast differentiation was associated with the downregulation of ADAM10 and ADAM17, which reduced their suppressive effects. We therefore propose that this downregulation serves as a feedback loop for enhancing osteoclast development.

Common and uncommon mouse models of growth hormone deficiency.

Mouse models of growth hormone deficiency (GHD) have provided important tools for uncovering the various actions of GH. Nearly 100 years of research using these mouse lines has greatly enhanced our knowledge of the GH/IGF-1 axis. Some of the shared phenotypes of the five "common" mouse models of GHD include reduced body size, delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, and enhanced insulin sensitivity. Since these common mouse lines outlive their normal-sized littermates - and have protection from age-associated disease - they have become important fixtures in the aging field. On the other hand, the twelve "uncommon" mouse models of GHD described herein have tremendously divergent health outcomes ranging from beneficial aging phenotypes (similar to those described for the common models) to extremely detrimental features (such as improper development of the CNS, numerous sensory organ defects, and embryonic lethality). Moreover, advancements in next generation sequencing technologies have led to the identification of an expanding array of genes that are recognized as causative agents to numerous rare syndromes with concomitant GHD. Accordingly, this review provides researchers with a comprehensive up-to-date collection of the common and uncommon mouse models of GHD that have been used to study various aspects of physiology and metabolism associated with multiple forms of GHD. For each mouse line presented, the closest comparable human syndromes are discussed providing important parallels to the clinic.

Activation of the aryl hydrocarbon receptor improves allergen-specific immunotherapy of murine allergic airway inflammation: a novel adjuvant option?

Background: Allergen-specific immunotherapy (AIT) is able to restore immune tolerance to allergens in allergic patients. However, some patients do not or only poorly respond to current treatment protocols. Therefore, there is a need for deeper mechanistic insights and further improvement of treatment strategies. The relevance of the aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor, has been investigated in several inflammatory diseases, including allergic asthma. However, its potential role in AIT still needs to be addressed. Methods: A murine model of AIT in ovalbumin-induced allergic airway inflammation was performed in AhR-deficient (AhR-/-) and wild-type mice. Furthermore, AIT was combined with the application of the high-affinity AhR agonist 10-chloro-7H-benzimidazo[2,1-a]benzo[de]iso-quinolin-7-one (10-Cl-BBQ) as an adjuvant to investigate the effects of AhR activation on therapeutic outcome. Results: Although AhR-/- mice suffer stronger allergic responses than wild-type mice, experimental AIT is comparably effective in both. Nevertheless, combining AIT with the administration of 10-Cl-BBQ improved therapeutic effects by an AhR-dependent mechanism, resulting in decreased cell counts in the bronchoalveolar fluid, decreased pulmonary Th2 and Th17 cell levels, and lower sIgE levels. Conclusion: This study demonstrates that the success of AIT is not dependent on the AhR. However, targeting the AhR during AIT can help to dampen inflammation and improve tolerogenic vaccination. Therefore, AhR ligands might represent promising candidates as immunomodulators to enhance the efficacy of AIT.

Multi-layered metabolic effects of trehalose on the liver proteome in apoE-knockout mice model of liver steatosis.

BACKGROUND: Metabolic dysfunction-associated fatty liver disease has been well documented as a key independent risk factor for the development of atherosclerosis. A growing body of evidence suggests that due to its numerous favorable molecular effects, trehalose may exert beneficial effects in counteracting liver steatosis. In our previous study, we described the antiatherosclerotic and antisteatotic properties of trehalose, which we attributed to the induction of autophagy. Considering the pleiotropic activities of trehalose, our present study aimed to extend our preliminary results with the comprehensive examination of proteome-wide changes in the livers of high-fat-fed apoE-/- mice. METHODS: Thus, we applied modern, next-generation proteomic methodology to comprehensively analyze the effects of trehalose on the alterations of liver proteins in apoE-/- mice. RESULTS: Our proteomic analysis showed that the administration of trehalose elicited profound changes in the liver proteome of apoE-/- mice. The collected data allowed the identification and quantitation of 3 681 protein groups of which 129 were significantly regulated in the livers of trehalose-treated apoE-/- mice. CONCLUSIONS: The presented results are the first to highlight the effects of disaccharide on the induction of proteins mainly related to the metabolism and elimination of lipids, especially by peroxisomal ß-oxidation. Our study provides evidence for the pleiotropic activity of trehalose, extending our initial observations of its potential mechanisms responsible for mitigating of liver steatosis, which paves the way for new pharmacological strategies in fatty liver disease.