Exploring the mechanism of interaction between TBG and halogenated thiophenols: Insights from fluorescence analysis and molecular simulation.

Thyroxine-binding globulin (TBG) plays a vital role in regulating metabolism, growth, organ differentiation, and energy homeostasis, exerting significant effects in various key metabolic pathways. Halogenated thiophenols (HTPs) exhibit high toxicity and harmfulness to organisms, and numerous studies have demonstrated their thyroid-disrupting effects. To understand the mechanism of action of HTPs on TBG, a combination of competitive binding experiments, multiple fluorescence spectroscopy techniques, molecular docking, and molecular simulations was employed to investigate the binding mechanism and identify the binding site. The competition binding assay between HTPs and ANS confirmed the competition of HTPs with thyroid hormone T4 for the active site of TBG, resulting in changes in the TBG microenvironment upon the binding of HTPs to the active site. Key amino acid residues involved in the binding process of HTPs and TBG were further investigated through residue energy decomposition. The distribution of high-energy contributing residues was determined. Analysis of root-mean-square deviation (RMSD) demonstrated the stability of the HTPs-TBG complex. These findings confirm the toxic mechanism of HTPs in thyroid disruption, providing a fundamental reference for accurately assessing the ecological risk of pollutants and human health. Providing mechanistic insights into how HTPS causes thyroid diseases.

Identification of Mutations in the Thyroxine-Binding Globulin (TBG) Gene in Patients with TBG Deficiency in Korea.

BACKGRUOUND: Thyroxine-binding globulin (TBG) is a major transporter protein for thyroid hormones. The serpin family A member 7 (SERPINA7) gene codes for TBG, and mutations of the SERPINA7 gene result in TBG deficiency. Although more than 40 mutations have been reported in several countries, only a few studies of TBG deficiency and SERPINA7 gene mutation have been performed in Korea. The aim of this study is to review the clinical presentations and laboratory findings of patients with TBG deficiency and to investigate the types of SERPINA7 gene mutation. METHODS: Five unrelated Korean adults with TBG deficiency attending endocrinology clinic underwent SERPINA7 gene sequencing. Four patients harbored a SERPINA7 gene mutation. Serum thyroid hormones, anti-microsomal antibodies, and TBG were measured. Genomic DNA was extracted from whole blood. All exons and intron-exon boundaries of the TBG gene were amplified and sequencing was performed. RESULTS: Two patients were heterozygous females, and the other two were hemizygous males. One heterozygous female had coexisting hypothyroidism. The other heterozygous female was erroneously prescribed levothyroxine at a local clinic. One hemizygous male harbored a novel mutation, p.Phe269Cysfs*18, which caused TBG partial deficiency. Three patients had the p.Leu372Phefs*23 mutation, which is known as TBG-complete deficiency Japan (TBG-CDJ) and was also presented in previous mutation analyses in Korea. CONCLUSION: This study presents four patients diagnosed with TBG deficiency and provides the results of SERPINA7 gene sequencing. One novel mutation, p.Phe269Cysfs*18, causing TBD-partial deficiency and three cases of TBG-CDJ were demonstrated. It is necessary to identify TBG deficiency to prevent improper treatment. Also, sequencing of the SERPINA7 gene would provide valuable information about the TBG variants in Korea.

Thyroxine replacement modifies changes in deiodinase and thyroid hormone transporter expression induced by subclinical hypothyroidism in rats.

PURPOSE: The potential benefits of treating subclinical hypothyroidism (SCH) are unclear and still controversial. Thus, we surgically induced SCH in rats and evaluated the effects of thyroxine (T4) replacement on the gene expression levels of deiodinases and thyroid hormone (TH) transporters in different tissues. METHODS: SCH was induced by hemithyroid electrocauterization. The control animals underwent the same surgical procedure but were not subjected to electrocauterization (sham). After 14 days, half of the SCH animals were treated with T4 (SCH + T4). At the end of the experimental protocol, all of the rats were euthanized, serum hormone concentrations were measured, and RNA analyses were performed on different tissues and organs. RESULTS: Consistent with previous studies, we observed increased TSH levels, normal TH levels, and reduced hypothalamic TRH expression in the SCH group. Additionally, Dio2 mRNA expression was downregulated in the hippocampus and pituitary, and Dio1 was upregulated in the kidney and pituitary of the SCH animals. The changes in Dio3 expression were tissue-specific. Concerning TH transporters, Mct10 expression was upregulated in the pituitary, kidney, hypothalamus, and hippocampus, and Mct8 expression was downregulated in the kidney of the SCH group. Crym expression was upregulated in the kidney and pituitary. Notably, T4 replacement significantly attenuated serum TSH levels and reverted Dio1, Dio2, Mct10, and Crym expression in the pituitary, hippocampus, and kidney to levels that were similar to the sham group. Tissue-specific responses were also observed in the liver and hypothalamus. CONCLUSION: Our results indicate that treatment of SCH should be considered before the appearance of clinical symptoms of hypothyroidism.

Study on the binding characteristics of hydroxylated polybrominated diphenyl ethers and thyroid transporters using the multispectral technique and computational simulation.

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are a class of toxic environmental pollutants that are persistent, bioaccumulative, and difficult to degrade. Their structure is very similar to the thyroid hormone (T4) and uses the body's thyroid transporter (TTR) binding to interfere with the endocrine balance, disrupting the body's normal physiological activity. According to Fourier transform infrared spectroscopy and dynamics simulation of do_dssp module analysis, there are three kinds of OH-PBDEs that can induce TTR secondary structural changes. Fluorescence spectra and UV-Vis spectra show that for the three kinds of OH-PBDEs for TTR, the main methods of quenching are static quenching and non-radiative energy transfer. According to thermodynamic analysis, ΔG < 0, ΔH > 0, and ΔS > 0 combine to show that the hydrophobic interaction is the main driving force of the combination. From the molecular docking analysis, it was found that 4'-hydroxy-2,2',4,5'- tetrabromodiphenyl ether (4'-OH-BDE49) and 4 hydroxy-2,2',3,4',5,6,6'- heptabromodiphenyl ether (4-OH-BDE188) had a cationic-π interaction with TTR, whereas 4 hydroxy-2,2',3,4,5,5',6- heptabromodiphenyl ether (4-OH-BDE187) was bonded to TTR by hydrogen bonds to form stable complexes. In this paper, we highlight the consistency of spectroscopic experiments and computer simulations so as to provide a reliable analytical method for the toxicological properties of small molecule contaminants.

Possible mechanism for the polychlorinated bipheny-linduced liver-selective accumulation of thyroxine in rats.

We have previously reported that decrease in level of serum thyroxine T4 by Kanechor 500 (KC500) in rats would occur through the increase in hepatic T4 accumulation rather than the increase in hepatic T4-glucuronyl transferase activity. In the present study, to understand the mechanism underlying the KC500-mediated increase in hepatic T4 accumulation, we examined the relationship between the KC500-mediated changes in hepatic T4 accumulation and the expression levels of mRNAs of hepatic transporters including T4 transporters. [125I]T4 was intravenously injected into KC500-pretreated and control (KC500-untreated) Wistar rats, and [125I]T4 uptake levels of liver parenchymal cells were comparatively examined. The amount of [125I]T4 uptake by hepatic cells increased in a time-dependent manner up to 96 hr after KC500 treatment. Following KC500 treatment, a time-dependent increase in the mRNA level of hepatic T4 influx transporter LAT1 was observed up to 96 hr later, while a significant increase in hepatic T4 influx transporter Oatp2 mRNA occurred only at 96 hr later. No KC500-mediated increases in the mRNAs of other hepatic transporters (Oatp1, Oatp3, Oatp4, Ntcp, LAT2, and Mrp2) were observed at any timepoints, although the mRNA expression of the T4 conjugate(s) efflux transporter Mrp3 significantly increased in a time-dependent manner 24-96 hr following KC500 treatment. The present findings suggest that KC500-mediated increase in hepatic T4 accumulation occurs, at least in part, through the increase in the expression of hepatic T4-transporters, such as LAT1 and Oatp2.

Inherited defects of thyroxine-binding proteins.

Thyroid hormones (TH) are bound to three major serum transport proteins, thyroxine-binding globulin (TBG), transthyretin (TTR) and human serum albumin (HSA). TBG has the strongest affinity for TH, whereas HSA is the most abundant protein in plasma. Individuals harboring genetic variations in TH transport proteins present with altered thyroid function tests, but are clinically euthyroid and do not require treatment. Clinical awareness and early recognition of these conditions are important to prevent unnecessary therapy with possible untoward effects. This review summarizes the gene, molecular structure and properties of these TH transport proteins and provides an overview of their inherited abnormalities, clinical presentation, genetic background and pathophysiologic mechanisms.

Heredity and lifestyle in the determination of between-subject variation in thyroid hormone levels in euthyroid men.

OBJECTIVE: Variation in thyroid hormone (TH) concentrations between subjects is greater than in a single subject over a prolonged period of time, suggesting an individual set point for thyroid function. We have previously shown that TH levels within normal range are associated with clinical indices such as bone mass, BMI, and heart rate. The aim of this study on young men was therefore to gain insight into the determinants of variation in TH levels among healthy subjects. METHODS: Healthy male siblings (n=941, 25-45 years) were recruited in a cross-sectional, population-based study; a history or treatment of thyroid disease and thyroid auto-immunity were exclusion criteria. A complete assessment of TH status was performed (TSH, free thyroxine (FT4), free triiodothyronine (FT3), thyroperoxidase, and thyroglobulin antibodies, reverse T3 (rT3), thyroid-binding globulin (TBG), and urinary iodine levels). Genotyping was performed by TaqMan and KASP (KBiosciences) genotyping assays. RESULTS: (F)T4, rT3, and TBG had heritability estimates between 80 and 90%. Estimates were lower for (F)T3 (60%) and lowest for TSH (49%). Significant associations were observed between different single-nucleotide polymorphisms (SNPs) in the thyroid pathway and TSH, FT4, ratio FT3:FT4, and rT3. Nevertheless, these SNPs only explain a limited part of the heredity. As to age and lifestyle-related factors, (F)T3 was negatively related to age and education level, positively to smoking and BMI (all P<0.0001) but not substantially to urinary iodine concentrations. Smoking was also negatively related to TSH and positively to FT4. CONCLUSION: Both genetic and lifestyle-related factors play a role in determining between-subject variation in TH levels in euthyroid young men, although genetic factors seem most important.

Dysthyronemia in normal concentrations of thyrotropin--analytical and clinical consequences.

This article discusses the conditions that may lead to a phenomenon called dysthyronemia. Here, the thyroid gland has concentration of thyrotropin in circulation within the reference range, but the concentrations of free or total fractions of thyroid hormones are outside the reference range. Normal values of thyrotropin (TSH) and increased values of THs are referred to as hyperthyroxinemia, while normal values of thyrotropin and decreased values of thyroid hormone are hypothyroxinemia. As shown by our observations, it is a relatively frequent situation in the parallel determinations of TSH and free thyroxine, when results verging on hyperthyroxinemia were found in 7% of cases (6.74%, n=259,590), and also in the parallel sets of TSH and total triiodothyronine when hypotriiodothyroninemia reached 8.5% (8.48%, n=73,143). We are assuming that the main cause of hyperthyroxinemia in the free thyroxine and TSH system is the presence of autoantibodies against thyroxine in patients with autoimmune thyroid disease. The reason of hypotriiodothyroninemia in the system of triiodothyronine and TSH is a decreased concentration of thyroid binding globulin in postmenopausal women. Manufacturers of immunoanalytical kits should take into account the potential adverse effects of autoantibodies against thyroid hormones when measuring the results of immunoassay determination of the free fraction of these hormones.

Body composition and metabolic parameters are associated with variation in thyroid hormone levels among euthyroid young men.

OBJECTIVE: Thyroid disorders affect metabolism and body composition. Existing literature has been conflicting on whether this is also the case for thyroid hormone levels within the euthyroid range. Therefore, we have investigated the relationship between thyroid hormone concentrations and body composition together with metabolic parameters in a population of healthy euthyroid men. METHODS: Healthy male siblings (n=941, 25-45 years, median BMI 24.6) were recruited in a cross-sectional, population-based study; a history or treatment of thyroid disease and thyroid autoimmunity were exclusion criteria. Body composition and muscle cross-sectional area were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Total (triiodothyronine (T(3); TT(3)) thyroxine and (T(4); TT(4))) and free thyroid hormones (FT(3) and FT(4)), TSH, and reverse T(3) (rT(3)) and thyroid-binding globulin (TBG) were determined using immunoassays. RESULTS: BMI was positively associated with (F)T(3) (P<0.0001). Whole body fat mass displayed positive associations with TT(3) and with (F)T(4) and TBG (P≤0.0006). Positive associations were further observed between leptin and (F)T(3), TT(4), and TBG (P≤0.0002). Inverse associations between lean mass and muscle cross-sectional area and (F)T(3), (F)T(4), and TBG were observed (P≤0.0003). Higher levels of (F)T(3) and TBG were associated with lower insulin sensitivity, assessed by homeostatic model assessment of insulin resistance (IR; P≤0.0001). No associations between TSH and body composition or metabolic parameters were seen. CONCLUSION: We show that a less favorable body composition (with higher fat and lower muscle mass and accompanying higher leptin concentrations) and IR are associated with higher thyroid hormone levels in healthy young men with well characterized euthyroidism.

A transgenic approach to identify thyroxine transporter-expressing structures in brain development.

Transporters are essential in thyroid hormone metabolism. Thyroxine (T4) is transported by solute carrier organic anion transporter 1c1 (SLCO1C1, OATP14) into the adult brain, where T4 is converted to 3,5,3'-triiodothyronine (T3). In adults, SLCO1C1 expression is found in two brain barrier structures: the blood-brain barrier (BBB) and choroid plexus. However, little is known about how T4 is transported in the developing brain, when the BBB is not yet completely formed. We employed bacterial artificial chromosome recombineering to generate transgenic mice carrying Cre recombinase in the Slco1c1 locus (Slco1c1-Cre mice). In Slco1c1-Cre mice Cre was expressed at the sites that have been previously reported for SLCO1C1 in adults. To trace Cre expression during development, we crossed Slco1c1-Cre transgenic mice with Rosa26 reporter mice. ß-galactosidase staining showed Cre activity in neurones of various brain structures, such as cortical layer 2/3 and the hippocampus, suggesting transient Slco1c1 expression during brain development. At embryonic day15, SLCO1C1 was expressed at the same site as TBR2, a marker of neuronal progenitors. Neurones that express SLCO1C1 during their development could be T4 sensitive. In support of this hypothesis, hypothyroxinaemia induced by propylthiouracil treatment of dams decreased the number of ß-galactosidase-positive neurones in cortical layer 2/3 of newborn Slco1c1-Cre/Rosa26 mice. In conclusion, by generating Slco1c1-Cre transgenic mice, we demonstrated that SLCO1C1 is expressed in the neuronal cell lineage during brain development. Expression of SLCO1C1 may underlie the extraordinary sensitivity of specific neuronal populations to hypothyroxinaemia.

Structure-activity relationship study on the binding of PBDEs with thyroxine transport proteins.

Molecular docking and three-dimensional quantitative structure-activity relationships (3D-QSAR) were used to develop models to predict binding affinity of polybrominated diphenyl ether (PBDE) compounds to the human transthyretin (TTR). Based on the molecular conformations derived from the molecular docking, predictive comparative molecular similarity indices analysis (CoMSIA) models were developed. The results of CoMSIA models were as follows: leave-one-out (LOO) cross-validated squared coefficient q² (LOO) = 0.827 (full model, for all 28 compounds); q² (LOO) = 0.752 (split model, for 22 compounds in the training set); leave-many-out (LMO) cross-validated squared coefficient q² (LMO, two groups) = 0.723 ± 0.100 (full model, for all 28 compounds); q² (LMO, five groups) = 0.795 ± 0.030 (full model, for all 28 compounds); and the predictive squared correlation coefficient r²(pred) = 0.928 (for six compounds in the test set). The developed CoMSIA models can be used to infer the activities of compounds with similar structural characteristics. In addition, the interaction mechanism between hydroxylated polybrominated diphenyl ethers (HO-PBDEs) and the TTR was explored. Hydrogen bonding with amino acid residues Asp74, Ala29, and Asn27 may be an important determinant for HO-PBDEs binding to TTR. Among them, forming hydrogen bonds with amino acid residues Asp74 might exert a more important function.

Blood plasma sample preparation method for the assessment of thyroid hormone-disrupting potency in effect-directed analysis.

A sample preparation method combining solid-phase extraction (SPE) and liquid-liquid extraction (LLE) was developed to be used in Effect-Directed Analysis (EDA) of blood plasma. Until now such a method was not available. It can be used for extraction of a broad range of thyroid hormone (TH)-disruptors from plasma with high recoveries. Validation of the method using spiked cow plasma showed good recoveries for hydroxylated polybrominated diphenyl ethers (OH-PBDEs; 93.8 ± 19.5%), hydroxylated polychlorinated biphenyls (OH-PCBs; 93.8 ± 15.5%), other halogenated phenols (OHPs; 107 ± 8.1%), and for short-chain (<8 C-atoms) perfluoroalkyl substances (PFASs; 85.2 ± 24.6%). In the same extracts, the potency of the compound classes spiked to the cow plasma to competitively bind to transthyretin (TTR) was recovered by 84.9 ± 8.8%. Furthermore, the SPE-LLE method efficiently removed endogenous THs from the extracts, thereby eliminating their possible contribution to the binding assay response. The SPE-LLE method was applied to polar bear plasma samples to investigate its applicability in future EDA studies focusing on TH-disrupting compounds in this top predator species that is exposed to relatively high levels of bioaccumulating pollutants. A first screening revealed TTR-binding potency in the polar bear plasma extracts, which could be explained for 60-85% by the presence of OH-PCBs.

Oxygen concentration regulates expression and uptake of transthyretin, a thyroxine binding protein, in JEG-3 choriocarcinoma cells.

Maternal thyroid hormone is provided to the fetus before the onset of fetal thyroid function (at about 16 weeks) and is essential for normal neurologic development. Mechanisms of transport are uncertain but transthyretin (TTR), a thyroxine binding protein produced by the placenta may be involved. Placental oxygen concentrations in early pregnancy are low, about 1% early in the first trimester and rising to 8% over the next 12 weeks. This study investigated the regulation of TTR expression, secretion and uptake in JEG-3 placental cells cultured at different oxygen concentrations. TTR mRNA and protein expression and (125)I-TTR and Alexa-Fluor594-TTR uptake were significantly higher in cells cultured at 1% and 3% O(2), than at 8% O(2). This suggests that increased carrier mediated T(4) transport by placental TTR may be induced by the low oxygen environment of early pregnancy, a time when the fetus has its highest requirement for transport of maternal T(4).

Structure-based investigation on the binding interaction of hydroxylated polybrominated diphenyl ethers with thyroxine transport proteins.

Polybrominated diphenyl ethers (PBDEs) have been shown to alter thyroid hormone level in experimental animals. One of the possible mechanisms for hormone disruption is the competitive binding of hydroxylated PBDEs (OH-PBDEs) with hormone transport proteins. In this study, binding interaction of 14 diversely structured OH-PBDEs with two thyroxine transport proteins was investigated by fluorescence displacement assay, circular dichroism, and molecular docking. Binding affinity of the 14 OH-PBDEs with transthyretin (TTR) and thyroxine-binding globulin (TBG) was measured by competitive fluorescence displacement assay. The binding constant was found to fall in the range of 1.4 x 107 M and 6.9 x 108 M⁻¹ for TTR, and between 6.5 x 106 M⁻¹ and 2.2 x 108 M⁻¹ for TBG. Binding affinity increased significantly with bromination number from 1 to 4, whereas 5- and 6-brominated diphenyl ethers did not show any further increase. Protein secondary structural change of TTR and TBG upon binding with 5-OH-BDE-047 was investigated by circular dichroism. The spectral change displayed a pattern similar to the one with thyroxine, suggesting that the environmental chemical binds to the two proteins at the same sites as the hormone. In molecular docking analysis, a ligand-binding channel in TTR was revealed for OH-PBDEs binding, which appeared to be mostly hydrophobic inside but guarded by positively charged residue Lys15 at the entrance. Binding affinity of the 14 OH-PBDEs with TTR could be rationalized reasonably well by their pocket binding mode and hydrophobic characteristics. Based on the binding constant obtained in this work, possibility of in vitro competitive displacement of thyroid hormones from the transport proteins by OH-PBDEs was evaluated.

Therapeutic drug monitoring during pregnancy and lactation: thyroid function assessment in pregnancy-challenges and solutions.

The diagnosis and monitoring of thyroid disease necessitates the knowledge of thyroid pathophysiology and of the technical limitations of current thyroid-related biochemical tests. Thyroid disease diagnosis and monitoring are further complicated during pregnancy and lactation, due to pregnancy-related changes in thyroid hormone metabolism. Dramatic changes that occur in thyroxine and triiodothyronine ranges during pregnancy pose challenges for hypothyroid gravidas. Very early in pregnancy, levothyroxine replacement needs to be increased. Moreover, increases in thyroid hormone replacement need to be conducted individually and on a timely basis. For reasons that are still not entirely clear, although dependent in part on changes in thyroxine binding, free thyroxine (FT4) levels decrease as pregnancy progresses necessitating the use of trimester-specific reference intervals for appropriate replacement. Thyroxine binding protein levels vary by hormonal status, inheritance, and disease states and are higher in pregnancy; hence, FT4 assays became popular because they measure the unbound hormone. However, current FT4 immunoassays are estimate tests that do not reliably measure FT4 and are known to be sensitive to alterations in binding proteins and therefore are method-specific. The need to reliably identify hypothyroxinemic pregnant patients, especially in the first trimester, is of prime importance for early fetal brain development before the fetal thyroid functions. This article addresses 1) the current limitations of laboratory-free thyroxine immunoassay methodologies and especially during pregnancy; 2) trimester-specific reference intervals for thyroid function tests; and 3) the study of levothyroxine pharmacokinetics in pregnant and nonpregnant women.

Liver-directed recombinant adeno-associated viral gene delivery rescues a lethal mouse model of methylmalonic acidemia and provides long-term phenotypic correction.

Methylmalonic acidemia is a severe metabolic disorder caused by a deficiency of the ubiquitously expressed mitochondrial enzyme, methylmalonyl-CoA mutase (MUT). Liver transplantation has been used to treat a small number of patients with variable success, and whether liver-directed gene therapy might be employed in such a pleiotropic metabolic disorder is uncertain. In this study, we examined the therapeutic effects of hepatocyte-directed delivery of the Mut gene to mice with a severe form of methylmalonic acidemia. We show that a single intrahepatic injection of recombinant adeno-associated virus serotype 8 expressing the Mut gene under the control of the liver-specific thyroxine-binding globulin (TBG) promoter is sufficient to rescue Mut(-/-) mice from neonatal lethality and provide long-term phenotypic correction. Treated Mut(-/-) mice lived beyond 1 year of age, had improved growth, lower plasma methylmalonic acid levels, and an increased capacity to oxidize [1-(13)C]propionate in vivo. The older treated mice showed increased Mut transcription, presumably mediated by upregulation of the TBG promoter during senescence. The results indicate that the stable transduction of a small number of hepatocytes with the Mut gene can be efficacious in the phenotypic correction of an inborn error of organic acid metabolism and support the rapid translation of liver-directed gene therapy vectors already optimized for human subjects to patients with methylmalonic acidemia.

Evolutionary changes to transthyretin: developmentally regulated and tissue-specific gene expression.

A survey of the expression of the transthyretin and thyroxine-binding globulin genes in various species during development provides clues as to how the present thyroid hormone distribution network in extracellular compartments developed during vertebrate evolution. Albumin may be the 'oldest' component of the thyroid hormone distribution network as it is found in the plasma of all vertebrates investigated. Subsequent to albumin, transthyretin appeared as the second component in this network during the evolution of vertebrates. The strong expression of transthyretin genes in the liver coincides with the presence of recognition site(s) for liver-enriched transcription factors, such as HNF-3beta (Foxa2), in the transthyretin promoter regions of vertebrates. Finally, the addition of thyroxine-binding globulin to this network occurred at postnatal stages in some marsupials and rodents and in perinatal to adult stages in most eutherians. All vertebrates have defined developmental stages when thyroid hormone-dependent transition from larval to juvenile forms occurs. The inclusion of transthyretin and thyroxine-binding globulin in the thyroid hormone distribution network may be correlated with the increased requirement of thyroid hormones for thyroid hormone-dependent tissue remodeling during these stages and/or increased metabolism in thyroid hormone-target tissues with the acquisition of homeothermy.

A novel variant in Serpina7 gene in a family with thyroxine-binding globulin deficiency.

Thyroxine-binding globulin (TBG) carries approximately 75% of serum T4 and T3. This protein is encoded by serpina7 gene, formerly known as TBG gene, localized on X-chromosome (Xq22.2). A deficiency in TBG is suspected when abnormally low serum total T4 and T3 are encountered in clinically euthyroid subjects in the presence of normal serum TSH. This condition has been associated with different serpina7 gene mutations resulting in amino acid substitutions or truncations in the mature protein. Herein, we report a new serpina7 gene variant in three members of the same family. It results in the replacement of the normal asparagine 233 by isoleucine and, subsequently, in disruption of a glycosylation site. Co-segregation of this new variant with undetectable levels of TBG in the hemizygous man studied and failure to recognize the same variant in 100 alleles at random, made us to consider it as the underlying cause of the TBG deficiency.

Gene expression profiling in rat liver after VMH lesioning.

It has been reported that ventromedial hypothalamic (VMH) lesions induce hepatic cell proliferation and apoptosis and metabolic changes in the body. In the present study, we identified genes of which expression profiles showed significant modulation in rat liver after VMH lesions. Total RNA was extracted, and differences in the gene expression profiles between rats at day 3 after VMH lesioning and sham-VMH lesioned rats were investigated using DNA microarray analysis. The results revealed that VMH lesions regulated the genes that were involved in various types of metabolisms and cell proliferations in the liver. Real-time PCR also confirmed that gene expressions of ELOVL6 and SPC24 were upregulated, and that of SERPINA7 was downregulated. VMH lesions may change the expressions of multiple metabolism genes and cell proliferation-related genes in rat liver.