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Congenital hypothyroidism (CH) is a neonatal endocrine disorder that might occur as itself or be associated to congenital extra-thyroidal defects. About 85% of affected subjects experience thyroid dysgenesis (TD), characterized by defect in thyroid gland development. In vivo experiments on null mice paved the way for the identification of genes involved thyroid morphogenesis and development, whose mutation has been strongly associated to TD. Most of them are thyroid-specific transcription factors expressed during early thyroid development. Despite the arduous effort in unraveling the genetics of TD in animal models, up to now these data have been discontinuously confirmed in humans and only 5% of TD have associated with known null mice-related mutations (mainly PAX8 and TSHR). Notwithstanding, the advance in genetic testing represented by the next-generation sequencing (NGS) approach is steadily increasing the list of genes whose highly penetrant mutation predisposes to TD. In this review we intend to outline the molecular bases of TD, summarizing the current knowledge on thyroid development in both mice and humans and delineating the genetic features of its monogenetic forms. We will also highlight current strategies to enhance the insight into the non-Mendelian mechanisms of abnormal thyroid development.

In the central nervous system, the extracellular matrix (ECM) compound laminin-2, present on developing axons, is essential in regulating oligodendrocyte (OLG) maturation. For example, laminin-2 is involved in mediating interactions between integrins and growth factors, initially localizing in separate membrane microdomains. The galactosphingolipid sulfatide is an important constituent of these microdomains and may serve as a receptor for laminin-2. Here, we investigated whether sulfatide interferes with ECM-integrin interactions and, in this manner, modulates OLG maturation. Our data reveal that disruption of laminin-2-sulfatide interactions impeded OLG differentiation and myelin-like membrane formation. On laminin-2, but not on (re)myelination-inhibiting fibronectin, sulfatide laterally associated with integrin alpha 6 in membrane microdomains. Sulfatide was partly excluded from membrane microdomains on fibronectin, thereby likely precluding laminin-2-mediated myelination. Anti-sulfatide antibodies disrupted integrin alpha 6-PDGF alpha R interactions on laminin-2 and induced demyelination in myelinated spheroid cultures, but intriguingly stimulated myelin-like membrane formation on fibronectin. Taken together, these findings highlight the importance of laminin-sulfatide interactions in the formation of functional membrane microdomains essential for myelination. Thus, laminin-sulfatide interactions might control the asynchronous localized differentiation of OLGs, thereby allowing myelination to be triggered by axonal demand. Given the accumulation of fibronectin in multiple sclerosis lesions, the findings also provide a molecular rationale for the potential of anti-sulfatide antibodies to trigger quiescent endogenous OLG progenitor cells in axon remyelination. GLIA 2014;62:927-942

Schnurri-3 (Shn3) is an essential regulator of postnatal skeletal remodeling. Shn3-deficient mice (Shn3-/-) have high bone mass; however, their bone mechanical and material properties have not been investigated to date. We performed three-point bending of femora, compression tests of L3 vertebrae. We also measured intrinsic material properties, including bone mineralization density distribution (BMDD) and osteocyte lacunae section (OLS) characteristics by quantitative backscatter electron imaging, as well as collagen cross-linking by Fourier transform infrared microspectroscopy of femora from Shn3-/- and WT mice at different ages (6 weeks, 4 months, and 18 months). Moreover, computer modeling was performed for the interpretation of the BMDD outcomes. Femora and L3 vertebrae from Shn3-/- aged 6 weeks revealed increased ultimate force (2.2- and 3.2-fold, p < .01, respectively). Mineralized bone volume at the distal femoral metaphysis was about twofold (at 6 weeks) to eightfold (at 4 and 18 months of age) in Shn3-/- (p < .001). Compared with WT, the average degree of trabecular bone mineralization was similar at 6 weeks, but increased at 4 and 18 months of age (+12.6% and +7.7%, p < .01, respectively) in Shn3-/-. The analysis of OLS characteristics revealed a higher OLS area for Shn3-/- versus WT at all ages (+16%, +23%, +21%, respectively, p < .01). The collagen cross-link ratio was similar between groups. We conclude that femora and vertebrae from Shn3-/- had higher ultimate force in mechanical testing. Computer modeling demonstrated that in cases of highly increased bone volume, the average degree of bone matrix mineralization can be higher than in WT bone, which was actually measured in the older Shn3-/- groups. The area of 2D osteocyte lacunae sections was also increased in Shn3-deficiency, which could only partly be explained by larger remnant areas of primary cortical bone. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

The proper maintenance of telomeres is essential for genome stability. Mammalian telomere maintenance is governed by a number of telomere binding proteins, including the newly identified CTC1–STN1–TEN1 (CST) complex. However, the in vivo functions of mammalian CST remain unclear. To address this question, we conditionally deleted CTC1 from mice. We report here that CTC1 null mice experience rapid onset of global cellular proliferative defects and die prematurely from complete bone marrow failure due to the activation of an ATR-dependent G2/M checkpoint. Acute deletion of CTC1 does not result in telomere deprotection, suggesting that mammalian CST is not involved in capping telomeres. Rather, CTC1 facilitates telomere replication by promoting efficient restart of stalled replication forks. CTC1 deletion results in increased loss of leading C-strand telomeres, catastrophic telomere loss and accumulation of excessive ss telomere DNA. Our data demonstrate an essential role for CTC1 in promoting efficient replication and length maintenance of telomeres.

Tetranectin was originally purified from human serum on the basis of plasminogen kringle 4-binding properties. Tetranectin enhances plasminogen activation by a tissue-type plasminogen activator so that it has been suggested to play a role in tissue remodeling. We have generated mice with a targeted disruption of the tetranectin gene to elucidate the biological function of tetranectin. In this study, we showed that wound healing was markedly delayed in tetranectin-null mice compared with wild-type mice. A single full-thickness incision was made in the dorsal skin. By 14 days after the incision, the wounds fully healed in all wild-type mice based on the macroscopic closure; in contrast, the progress of wound healing in the tetranectin null mice appeared to be impaired. In histological analysis, wounds of wild-type mice showed complete reepithelialization and healed by 14 days after the incision. However, those of tetranectin-null mice never showed complete reepithelialization at 14 days. At 21 days after the injury, the wound healed and was covered with an epidermis. These results supported the fact that tetranectin may play a role in the wound healing process.

Recent evidence suggests that alterations in insulin/insulin-like growth factor 1 (IGF1) signaling (IIS) can increase mammalian life span. For example, in several mouse mutants, impairment of the growth hormone (GH)/IGF1 axis increases life span and also insulin sensitivity. However, the intracellular signaling route to altered mammalian aging remains unclear. We therefore measured the life span of mice lacking either insulin receptor substrate (IRS) 1 or 2, the major intracellular effectors of the IIS receptors. Our provisional results indicate that female Irs1-/- mice are long-lived. Furthermore, they displayed resistance to a range of age-sensitive markers of aging including skin, bone, immune, and motor dysfunction. These improvements in health were seen despite mild, lifelong insulin resistance. Thus, enhanced insulin sensitivity is not a prerequisite for IIS mutant longevity. Irs1-/- female mice also displayed normal anterior pituitary function, distinguishing them from long-lived somatotrophic axis mutants. In contrast, Irs2-/- mice were short-lived, whereas Irs1+/- and Irs2+/- mice of both sexes showed normal life spans. Our results therefore suggest that IRS1 signaling is an evolutionarily conserved pathway regulating mammalian life span and may be a point of intervention for therapies with the potential to delay age-related processes.

Activation of the KATP channels results in faster fatigue rates as the channels depress action potential amplitude, whereas abolishing the channel activity has no effect in whole extensor digitorum longus (EDL) and soleus muscles. In this study, we examined the effects of abolished KATP channel activity during fatigue at 37°C on free intracellular Ca2+(Ca2+i) and tetanic force using single muscle fibres and small muscle bundles from the flexor digitorum brevis (FDB). KATP channel deficient muscle fibres were obtained (i) pharmacologically by exposing wild-type fibres to glibenclamide, and (ii) genetically using null mice for the Kir6.2 gene (Kir6.2−/− mice). Fatigue was elicited using 200 ms tetanic contractions every second for 3 min. This study demonstrated for the first time that abolishing KATP channel activity at 37°C resulted in faster fatigue rates, where decreases in peak Ca2+i and tetanic force were faster in KATP channel deficient fibres than in control wild-type fibres. Furthermore, several contractile dysfunctions were also observed in KATP channel deficient muscle fibre. They included partially or completely supercontracted single muscle fibres, greater increases in unstimulated Ca2+i and unstimulated force, and lower force recovery. We propose that the observed faster rate of fatigue in KATP channel deficient fibres is because the decreases in peak Ca2+i and force caused by contractile dysfunctions prevail over the expected slower decreases when the channels do not depress action potential amplitude.

Objectives: Our macrophage-targeting epigallocatechin gallate (EGCG) nanocarriers (E-nano) have anti-atherogenic bioactivities. But their effects on liver cholesterol content are unknown. This stud...

Objectives: We successfully synthesize epigallocatechin gallate (EGCG) nanocarriers (E-nano), which have anti-atherogenic and anti-inflammatory bioactivities. But their effects on liver fat, primarily triglyceride, content have not been known yet. Therefore, we compared the effects of native EGCG and different types of E-nano on liver fat content in LDL receptor null (LDLr-/-) mice. Methods: Mice were fed an atherogenic diet and received weekly intravenous injection of the following 6 treatments for 20 weeks: saline, high dose (25 mg/kg body weight) of EGCG (EGCG-H), E-nano (E-nano-H), macrophage-targeting E-nano (TE-nano-H), and low dose (10 mg/kg body weight) of E-nano (E-nano-L), macrophage-targeting E-nano (TE-nano-L). Liver lipids were extracted by a chloroform/methanol mixture. Liver triglyceride content was measured using an enzymatic method. Liver fat content was determined using an EchoMRI scanning method. Results: Compared to other treatments, native EGCG significantly decreased liver fat conten...

Skeletal muscle atrophy is caused by a multitude of conditions, including denervation, corticosteroids, immobilization and aging. The nicotinic acetylcholine receptors cluster at the neuromuscular ...

An imbalance between glutamatergic and g-aminobutyric acid (GABA)ergic synaptic transmission is associated with hyperbaric oxygen (HBO2) induced seizures. Here we explored the impact of S-nitrosyla...

The functional significance of smooth muscle-specific h1-calponin up-regulation in the smooth muscle contractility of SM-B null mice was studied by generating double knockout mice lacking both h1-calponin and SM-B myosin. The double knockout mice appear healthy, reproduce well and do not show any smooth muscle pathology. Loss of h1-calponin in the SM-B null mice bladder resulted in increased maximal shortening velocity (Vmax) and steady-state force generation. The force dilatation pressure, which was decreased in the SM-B null mesenteric vessels, was restored to wild-type levels in the double knockout vessels. In contrast, the half-time to maximal constriction was significantly increased in the double knockout vessels similar to that of SM-B null mice and indicating decreased shortening velocity in the double knockout vessels. Biochemical analyses showed that there is a significant reduction in smooth muscle α-actin levels, whereas h-caldesmon levels are increased in the double knockout bladder and mesenteric vessels, suggesting that these changes may also partly contribute to the altered contractile function. Taken together, our studies suggest that up-regulation of h1-calponin in the SM-B null mice may be necessary to maintain a reduced level of cross-bridge cycling over time in the absence of SM-B myosin and play an important role in regulating the smooth muscle contraction.

PEPT2 is functionally active and localized to the apical membrane of rat choroid plexus epithelial cells. However, little is known about the transport mechanisms of endogenous neuropeptides in choroid plexus, and the role of PEPT2 in this process. In the present study, we examined the uptake kinetics of carnosine in rat choroid plexus primary cell cultures and choroid plexus whole tissue from wild-type (PEPT2(+/+)) and null (PEPT2(-/-)) mice. Our results indicate that carnosine is preferentially taken up from the apical as opposed to basolateral membrane of cell monolayers, and that basolateral efflux in limited. Transepithelial flux of carnosine was not distinguishable from that of paracellular diffusion. The apical uptake of carnosine was characterized by a high affinity (K(m) = 34 microM), low capacity (V(max) = 73 pmol/mg protein/min) process, consistent with that of PEPT2. The non-saturable component was small (K(d) = 0.063 microL/mg protein/min) and, under linear conditions, was only 3% of the total uptake. Studies in transgenic mice clearly demonstrated that PEPT2 was responsible for over 90% of carnosine's uptake in choroid plexus whole tissue. These findings elucidate the unique role of PEPT2 in regulating neuropeptide homeostasis at the blood-cerebrospinal fluid interface.

The farnesoid X receptor (FXR/Nr1h4) is a critical transcriptional regulator for genes involved in bile acid processing, as well as lipid and glucose metabolism. However, very little is shown regar...

We previously reported that a Western Diet increased levels of free arachidonic acid (AA) and its metabolites in the small intestine and plasma of LDLR null mice and increased plasma levels of serum amyloid A (SAA). To determine the role of AA metabolites in initiating inflammation, LDLR null mice on a chow diet were or were not administered 15-hydroxyeicosatetraenoic acid (15-HETE) at a dose of 5 μg/day (mixed into the chow) or the mice received 5 μg/day subcutaneously (SQ). After two weeks the mice were bled, perfused with saline to remove any remaining blood and the heart was harvested. Plasma levels of SAA were determined by ELISA and levels of free AA and its metabolites were determined in plasma by LC-ESI-MS/MS. Plasma SAA levels increased from 6.4 ± 1.9 ug/mL on chow without 15-HETE to 15 ± 7 ug/mL with oral 15-HETE (p

Myostatin inhibits while insulin-like growth factors (IGF) 1 and 2 increase pre- and postnatal skeletal muscle growth. However, the contribution of altered IGF expression to the hypermuscular pheno...

Fibrillar collagens give integrity and tensile strength to many organs in the body. Collagen XXIV is a non-traditional collagen in the fibrillar collagen family. To determine what its function might be in bone, collagen XXIV knock out (KO) mice were analyzed. Since femurs of null mice at 3 and 5 months of age were found to be osteoporotic compared to WT mice, our goal was to quantify mRNAs involved in regulation of bone deposition and resorption, and determine whether the loss of collagen XXIV affected their expression. Femur RNA was extracted from WT and KO mice at 7 days, 1 month, 2 months, 3 months, 6 months, 1 year and 1.5 years of age. RNA was converted to cDNA, and real time qPCR was performed using GAPDH as a control. In WT mice, collagen XXIV mRNA was high at 7 d and 1 month of age. At 2 months it was present at less than half of what it was at 1 month. By 3 months its levels were greatly attenuated. This trend continued for all ages up to 1.5 yrs. KO mice showed minor amounts of collagen XXIV mRN...

SOD1 null (SOD1-/-) mice are a powerful model to study the effects of ageing on musculoskeletal tissues. The aim of this study was to determine the effect of lack of SOD1 in mice on mechanical chan...

Thrombospondin-1 null mice exhibit enhanced microvessel endothelium dependent vasodilation, reduced adrenergic sensitivity The extracellular matrix protein thrombospondin -1 (TSP-1), is an antagoni...

Supernutritional selenium (Se, 4× RDA) in humans is associated with risk of diabetes. In mice, Se supplementation above the requirement is reported to elevate diabetes biomarkers (DB) and glutathio...