Thyroid hormones are essential for brain developat through specific time windows influencing neur... more Thyroid hormones are essential for brain developat through specific time windows influencing neurogenesis, neuronal migration, neuronal and glial cell differentiation, myelination, and synaptogenesis. The actions of thyroid hormones are mostly due to interaction of the active hormone T3 with nuclear receptors and regulation of gene expression. T4 and T3 also perform non-genomic actions. The genomically active T3 in brain derives in part from the circulation, and in part is formed locally by 5’-deiodination of T4, mediated by Dio2 in the astrocytes, in proportions that depend on the developmental stage. T4 and T3 are degraded by Dio3 present in neurons. Entry of T4 and T3 in brain is facilitated by specific transmembrane transporters, mainly the monocarboxylate transporter 8 (Mct8) and the organic anion transporter polypeptide 1c1 (Oatp1c1). In rodents Mct8 facilitates the transfer of T4 and T3 through the blood-brain barrier (BBB). Oatp1c1 transports T4 through the BBB and into to t...
The physiological and developmental effects of thyroid hormones are mainly due to the control of ... more The physiological and developmental effects of thyroid hormones are mainly due to the control of gene expression after interaction of T3with the nuclear receptors. To understand the role of thyroid hormones on cerebral cortex development, knowledge of the genes regulated by T3during specific stages of development is required. In our laboratory, we previously identified genes regulated by T3in primary cerebrocortical cells in culture. By comparing these data with transcriptomics of purified cell types from the developing cortex, the cellular targets of T3can be identified. In addition, many of the genes regulated transcriptionally by T3have defined roles in cortex development, from which the role of T3can be derived. This review analyzes the specific roles of T3-regulated genes in the different stages of cortex development within the physiological frame of the developmental changes of thyroid hormones and receptor concentrations in the human cerebral cortex during fetal development. ...
Mice deficient in the type 3 deiodinase (D3KO mice) manifest impaired clearance of thyroid hormon... more Mice deficient in the type 3 deiodinase (D3KO mice) manifest impaired clearance of thyroid hormone (TH), leading to elevated levels of TH action during development. This alteration causes reduced neonatal viability, growth retardation and central hypothyroidism. Here we examined how these phenotypes are affected by a deficiency in the monocarboxylate transporter 8 (MCT8), which is a major contributor to the transport of the active thyroid hormone, triiodothyronine (T3) into the cell. MCT8 deficiency eliminated the neonatal lethality of D3-deficient mice and significantly ameliorated their growth retardation. Double mutant newborn mice exhibited similar peripheral thyrotoxicosis and increased brain expression of T3-dependent genes as mice with D3 deficiency only. Later in neonatal life and adulthood, double mutant mice manifested central and peripheral TH status similar to mice with single MCT8 deficiency, with low serum T4, elevated serum TSH and T3, and decreased T3-dependent gene ...
Cerebral cortex (New York, N.Y. : 1991), Jan 2, 2015
Thyroid hormones, thyroxine, and triiodothyronine (T3) are crucial for cerebral cortex developmen... more Thyroid hormones, thyroxine, and triiodothyronine (T3) are crucial for cerebral cortex development acting through regulation of gene expression. To define the transcriptional program under T3 regulation, we have performed RNA-Seq of T3-treated and untreated primary mouse cerebrocortical cells. The expression of 1145 genes or 7.7% of expressed genes was changed upon T3 addition, of which 371 responded to T3 in the presence of cycloheximide indicating direct transcriptional regulation. The results were compared with available transcriptomic datasets of defined cellular types. In this way, we could identify targets of T3 within genes enriched in astrocytes and neurons, in specific layers including the subplate, and in specific neurons such as prepronociceptin, cholecystokinin, or cortistatin neurons. The subplate and the prepronociceptin neurons appear as potentially major targets of T3 action. T3 upregulates mostly genes related to cell membrane events, such as G-protein signaling, ne...
Proceedings of the National Academy of Sciences, 1997
Thyroid hormone plays an essential role in mammalian brain maturation and function, in large part... more Thyroid hormone plays an essential role in mammalian brain maturation and function, in large part by regulating the expression of specific neuronal genes. In this tissue, the type 2 deiodinase (D2) appears to be essential for providing adequate levels of the active thyroid hormone 3,5,3′-triiodothyronine (T3) during the developmental period. We have studied the regional and cellular localization of D2 mRNA in the brain of 15-day-old neonatal rats. D2 is expressed in the cerebral cortex, olfactory bulb, hippocampus, caudate, thalamus, hypothalamus, and cerebellum and was absent from the white matter. At the cellular level, D2 is expressed predominantly, if not exclusively, in astrocytes and in the tanycytes lining the third ventricle and present in the median eminence. These results suggest a close metabolic coupling between subsets of glial cells and neurons, whereby thyroxine is taken up from the blood and/or cerebrospinal fluid by astrocytes and tanycytes, is deiodinated to T3, an...
Thyroid hormone is an important regulator of mammalian brain maturation. By differential display ... more Thyroid hormone is an important regulator of mammalian brain maturation. By differential display PCR, we isolated a cDNA clone (S2) that is specifically up-regulated in the striatum of neonatal hypothyroid rats. S2 was identified as KIAA0719, the first human gene distantly homologous to the fungal Tom70, which encodes a member of the translocase mitochondrial outer membrane complex involved in the import of preproteins into the mitochondria. By northern and in situ hybridization studies, KIAA0719 was found to be up-regulated in the striatum, nucleus accumbens, and discrete cortical layers of 15-day-old hypothyroid rats. In contrast, lower expression was found in the olfactory tubercle, whereas no differences were detected in other brain regions. Significantly, treatment of hypothyroid animals with single injections of thyroxine restored the normal levels of KIAA0719 expression. Moreover, treatment of control animals with thyroxine led to a reduced expression, demonstrating a negative hormonal regulation in vivo. Thus, KIAA0719 gene expression is regulated by thyroid hormone in the neonatal rat brain in a region-specific fashion. Given the role of the homologous Tom70 gene, the alteration of KIAA0719 expression may contribute to the changes in mitochondrial morphology and physiology caused by hypothyroidism in the developing rat brain.
The Journal of Clinical Endocrinology & Metabolism, 1974
ABSTRACT A human congenital goiter has been shown to contain minute amounts of TG-like immunoreac... more ABSTRACT A human congenital goiter has been shown to contain minute amounts of TG-like immunoreactive material (1). The subcellular distribution of the TG-like antigens after differential centrifugation of the homogenate and digitonin solubilization of the particulate fractions has been studied by means of a RIA of TG: 61% of the antigens were found in the soluble fraction, and 21% and 16% in the nuclear and microsomal ones, respectively. The analysis of each fraction by linear sucrose density gradient ultracentrifugation revealed that the antigen was heterogeneous; the main component in the soluble and nuclear fractions was a 12S protein. A 6–7S component and small amounts of 19S were found in the microsomal fraction.
The transcriptional properties of unliganded thyroid hormone receptors are thought to cause the m... more The transcriptional properties of unliganded thyroid hormone receptors are thought to cause the misdevelopment during hypothyroidism of several functions essential for adult life. To specifically determine the role of unliganded thyroid hormone receptor α1 (TRα1) in neuronal tissues, we introduced a mutation into the mouse TRα1 gene that lowers affinity to thyroid hormone (TH) 10-fold. The resulting heterozygous mice exhibit several distinct neurological abnormalities: extreme anxiety, reduced recognition memory, and locomotor dysfunction. The anxiety and memory deficiencies were relieved by treatment with high levels of TH in adulthood, an effect that correlated with a normalization of GABAergic inhibitory interneurons in the hippocampal CA1 region. In contrast, a post-natal TH treatment was necessary and sufficient for ameliorating the adult locomotor dysfunction. Here, the hormone treatment normalized the otherwise delayed cerebellar development. The data thus identify two novel ...
Lipocalin-type prostaglandin D2 synthase is the enzyme responsible for the synthesis of prostagla... more Lipocalin-type prostaglandin D2 synthase is the enzyme responsible for the synthesis of prostaglandin D2, a major prostaglandin in the central nervous system. We analysed the effects of thyroid hormone deprivation on prostaglandin D2 synthase gene expression in the developing rat brain. By in situ hybridization, the strongest prostaglandin D2 synthase mRNA signal was detected in the leptomeninges and choroid plexus. The signal was greatly reduced in the cerebellar interlaminar meninges of hypothyroid rats aged 15 and 25 days. Immunohistochemical studies defined changes in the location of the prostaglandin D2 synthase protein. In control but not in hypothyroid animals, Cajal-Retzius neurons of cortical layer I, and pyramidal cortical plate neurons were intensely stained on postnatal day 5. Conversely, prostaglandin D2 synthase protein levels were higher in neurons of the CA1 and CA3 regions and the dentate gyrus of the hippocampus of hypothyroid animals on postnatal days 5, 15 and 25, and also in subplate neurons on postnatal days 15 and 25. In agreement with the in situ hybridization and northern blotting data, the major difference was found in the cerebellar interlaminar meninges of hypothyroid animals, where the protein was clearly down-regulated on postnatal days 15 and 25. These results show that hypothyroidism causes both age- and region-specific alterations in the expression and location of the prostaglandin D2 synthase during postnatal brain development, probably reflecting a cell-specific regulatory effect of thyroid hormone on the prostaglandin D2 synthase.
Thyroid hormones regulate brain development and function through the control of gene expression, ... more Thyroid hormones regulate brain development and function through the control of gene expression, mediated by binding of T3 to nuclear receptors. Brain T3 concentration is tightly controlled by homeostatic mechanisms regulating transport and metabolism of T4 and T3. We have examined the role of the inactivating enzyme type 3 deiodinase (D3) in the regulation of 43 thyroid hormone-dependent genes in the cerebral cortex of 30-d-old mice. D3 inactivation increased slightly the expression of two of 22 positively regulated genes and significantly decreased the expression of seven of 21 negatively regulated genes. Administration of high doses of T3 led to significant changes in the expression of 12 positive genes and three negative genes in wild-type mice. The response to T3 treatment was enhanced in D3-deficient mice, both in the number of genes and in the amplitude of the response, demonstrating the role of D3 in modulating T3 action. Comparison of the effects on gene expression observed...
Mutations of the gene expressing plasma membrane transporter for thyroid hormones MCT8 (SLC16A2) ... more Mutations of the gene expressing plasma membrane transporter for thyroid hormones MCT8 (SLC16A2) in humans lead to altered thyroid hormone levels and a severe neurodevelopmental disorder. Genetically engineered defect of the Mct8 gene in mice leads to similar thyroid hormone abnormalities but no obvious impairment of brain development or function. In this work we studied the relative role of the blood-brain barrier and the neuronal plasma cell membrane in the restricted access of T3 to the target neurons. To this end we compared the effects of low doses of T4 and T3 on cerebellar structure and gene expression in wild-type (Wt) and Mct8 null male mice [Mct8-/y, knockout (KO)] made hypothyroid during the neonatal period. We found that compared with Wt animals, T4 was considerably more potent than T3 in the Mct8KO mice, indicating a restricted access of T3, but not T4, to neurons after systemic administration in vivo. In contrast, T3 action in cultured cerebellar neurons was similar in...
Thyroid hormones are essential for brain developat through specific time windows influencing neur... more Thyroid hormones are essential for brain developat through specific time windows influencing neurogenesis, neuronal migration, neuronal and glial cell differentiation, myelination, and synaptogenesis. The actions of thyroid hormones are mostly due to interaction of the active hormone T3 with nuclear receptors and regulation of gene expression. T4 and T3 also perform non-genomic actions. The genomically active T3 in brain derives in part from the circulation, and in part is formed locally by 5’-deiodination of T4, mediated by Dio2 in the astrocytes, in proportions that depend on the developmental stage. T4 and T3 are degraded by Dio3 present in neurons. Entry of T4 and T3 in brain is facilitated by specific transmembrane transporters, mainly the monocarboxylate transporter 8 (Mct8) and the organic anion transporter polypeptide 1c1 (Oatp1c1). In rodents Mct8 facilitates the transfer of T4 and T3 through the blood-brain barrier (BBB). Oatp1c1 transports T4 through the BBB and into to t...
The physiological and developmental effects of thyroid hormones are mainly due to the control of ... more The physiological and developmental effects of thyroid hormones are mainly due to the control of gene expression after interaction of T3with the nuclear receptors. To understand the role of thyroid hormones on cerebral cortex development, knowledge of the genes regulated by T3during specific stages of development is required. In our laboratory, we previously identified genes regulated by T3in primary cerebrocortical cells in culture. By comparing these data with transcriptomics of purified cell types from the developing cortex, the cellular targets of T3can be identified. In addition, many of the genes regulated transcriptionally by T3have defined roles in cortex development, from which the role of T3can be derived. This review analyzes the specific roles of T3-regulated genes in the different stages of cortex development within the physiological frame of the developmental changes of thyroid hormones and receptor concentrations in the human cerebral cortex during fetal development. ...
Mice deficient in the type 3 deiodinase (D3KO mice) manifest impaired clearance of thyroid hormon... more Mice deficient in the type 3 deiodinase (D3KO mice) manifest impaired clearance of thyroid hormone (TH), leading to elevated levels of TH action during development. This alteration causes reduced neonatal viability, growth retardation and central hypothyroidism. Here we examined how these phenotypes are affected by a deficiency in the monocarboxylate transporter 8 (MCT8), which is a major contributor to the transport of the active thyroid hormone, triiodothyronine (T3) into the cell. MCT8 deficiency eliminated the neonatal lethality of D3-deficient mice and significantly ameliorated their growth retardation. Double mutant newborn mice exhibited similar peripheral thyrotoxicosis and increased brain expression of T3-dependent genes as mice with D3 deficiency only. Later in neonatal life and adulthood, double mutant mice manifested central and peripheral TH status similar to mice with single MCT8 deficiency, with low serum T4, elevated serum TSH and T3, and decreased T3-dependent gene ...
Cerebral cortex (New York, N.Y. : 1991), Jan 2, 2015
Thyroid hormones, thyroxine, and triiodothyronine (T3) are crucial for cerebral cortex developmen... more Thyroid hormones, thyroxine, and triiodothyronine (T3) are crucial for cerebral cortex development acting through regulation of gene expression. To define the transcriptional program under T3 regulation, we have performed RNA-Seq of T3-treated and untreated primary mouse cerebrocortical cells. The expression of 1145 genes or 7.7% of expressed genes was changed upon T3 addition, of which 371 responded to T3 in the presence of cycloheximide indicating direct transcriptional regulation. The results were compared with available transcriptomic datasets of defined cellular types. In this way, we could identify targets of T3 within genes enriched in astrocytes and neurons, in specific layers including the subplate, and in specific neurons such as prepronociceptin, cholecystokinin, or cortistatin neurons. The subplate and the prepronociceptin neurons appear as potentially major targets of T3 action. T3 upregulates mostly genes related to cell membrane events, such as G-protein signaling, ne...
Proceedings of the National Academy of Sciences, 1997
Thyroid hormone plays an essential role in mammalian brain maturation and function, in large part... more Thyroid hormone plays an essential role in mammalian brain maturation and function, in large part by regulating the expression of specific neuronal genes. In this tissue, the type 2 deiodinase (D2) appears to be essential for providing adequate levels of the active thyroid hormone 3,5,3′-triiodothyronine (T3) during the developmental period. We have studied the regional and cellular localization of D2 mRNA in the brain of 15-day-old neonatal rats. D2 is expressed in the cerebral cortex, olfactory bulb, hippocampus, caudate, thalamus, hypothalamus, and cerebellum and was absent from the white matter. At the cellular level, D2 is expressed predominantly, if not exclusively, in astrocytes and in the tanycytes lining the third ventricle and present in the median eminence. These results suggest a close metabolic coupling between subsets of glial cells and neurons, whereby thyroxine is taken up from the blood and/or cerebrospinal fluid by astrocytes and tanycytes, is deiodinated to T3, an...
Thyroid hormone is an important regulator of mammalian brain maturation. By differential display ... more Thyroid hormone is an important regulator of mammalian brain maturation. By differential display PCR, we isolated a cDNA clone (S2) that is specifically up-regulated in the striatum of neonatal hypothyroid rats. S2 was identified as KIAA0719, the first human gene distantly homologous to the fungal Tom70, which encodes a member of the translocase mitochondrial outer membrane complex involved in the import of preproteins into the mitochondria. By northern and in situ hybridization studies, KIAA0719 was found to be up-regulated in the striatum, nucleus accumbens, and discrete cortical layers of 15-day-old hypothyroid rats. In contrast, lower expression was found in the olfactory tubercle, whereas no differences were detected in other brain regions. Significantly, treatment of hypothyroid animals with single injections of thyroxine restored the normal levels of KIAA0719 expression. Moreover, treatment of control animals with thyroxine led to a reduced expression, demonstrating a negative hormonal regulation in vivo. Thus, KIAA0719 gene expression is regulated by thyroid hormone in the neonatal rat brain in a region-specific fashion. Given the role of the homologous Tom70 gene, the alteration of KIAA0719 expression may contribute to the changes in mitochondrial morphology and physiology caused by hypothyroidism in the developing rat brain.
The Journal of Clinical Endocrinology & Metabolism, 1974
ABSTRACT A human congenital goiter has been shown to contain minute amounts of TG-like immunoreac... more ABSTRACT A human congenital goiter has been shown to contain minute amounts of TG-like immunoreactive material (1). The subcellular distribution of the TG-like antigens after differential centrifugation of the homogenate and digitonin solubilization of the particulate fractions has been studied by means of a RIA of TG: 61% of the antigens were found in the soluble fraction, and 21% and 16% in the nuclear and microsomal ones, respectively. The analysis of each fraction by linear sucrose density gradient ultracentrifugation revealed that the antigen was heterogeneous; the main component in the soluble and nuclear fractions was a 12S protein. A 6–7S component and small amounts of 19S were found in the microsomal fraction.
The transcriptional properties of unliganded thyroid hormone receptors are thought to cause the m... more The transcriptional properties of unliganded thyroid hormone receptors are thought to cause the misdevelopment during hypothyroidism of several functions essential for adult life. To specifically determine the role of unliganded thyroid hormone receptor α1 (TRα1) in neuronal tissues, we introduced a mutation into the mouse TRα1 gene that lowers affinity to thyroid hormone (TH) 10-fold. The resulting heterozygous mice exhibit several distinct neurological abnormalities: extreme anxiety, reduced recognition memory, and locomotor dysfunction. The anxiety and memory deficiencies were relieved by treatment with high levels of TH in adulthood, an effect that correlated with a normalization of GABAergic inhibitory interneurons in the hippocampal CA1 region. In contrast, a post-natal TH treatment was necessary and sufficient for ameliorating the adult locomotor dysfunction. Here, the hormone treatment normalized the otherwise delayed cerebellar development. The data thus identify two novel ...
Lipocalin-type prostaglandin D2 synthase is the enzyme responsible for the synthesis of prostagla... more Lipocalin-type prostaglandin D2 synthase is the enzyme responsible for the synthesis of prostaglandin D2, a major prostaglandin in the central nervous system. We analysed the effects of thyroid hormone deprivation on prostaglandin D2 synthase gene expression in the developing rat brain. By in situ hybridization, the strongest prostaglandin D2 synthase mRNA signal was detected in the leptomeninges and choroid plexus. The signal was greatly reduced in the cerebellar interlaminar meninges of hypothyroid rats aged 15 and 25 days. Immunohistochemical studies defined changes in the location of the prostaglandin D2 synthase protein. In control but not in hypothyroid animals, Cajal-Retzius neurons of cortical layer I, and pyramidal cortical plate neurons were intensely stained on postnatal day 5. Conversely, prostaglandin D2 synthase protein levels were higher in neurons of the CA1 and CA3 regions and the dentate gyrus of the hippocampus of hypothyroid animals on postnatal days 5, 15 and 25, and also in subplate neurons on postnatal days 15 and 25. In agreement with the in situ hybridization and northern blotting data, the major difference was found in the cerebellar interlaminar meninges of hypothyroid animals, where the protein was clearly down-regulated on postnatal days 15 and 25. These results show that hypothyroidism causes both age- and region-specific alterations in the expression and location of the prostaglandin D2 synthase during postnatal brain development, probably reflecting a cell-specific regulatory effect of thyroid hormone on the prostaglandin D2 synthase.
Thyroid hormones regulate brain development and function through the control of gene expression, ... more Thyroid hormones regulate brain development and function through the control of gene expression, mediated by binding of T3 to nuclear receptors. Brain T3 concentration is tightly controlled by homeostatic mechanisms regulating transport and metabolism of T4 and T3. We have examined the role of the inactivating enzyme type 3 deiodinase (D3) in the regulation of 43 thyroid hormone-dependent genes in the cerebral cortex of 30-d-old mice. D3 inactivation increased slightly the expression of two of 22 positively regulated genes and significantly decreased the expression of seven of 21 negatively regulated genes. Administration of high doses of T3 led to significant changes in the expression of 12 positive genes and three negative genes in wild-type mice. The response to T3 treatment was enhanced in D3-deficient mice, both in the number of genes and in the amplitude of the response, demonstrating the role of D3 in modulating T3 action. Comparison of the effects on gene expression observed...
Mutations of the gene expressing plasma membrane transporter for thyroid hormones MCT8 (SLC16A2) ... more Mutations of the gene expressing plasma membrane transporter for thyroid hormones MCT8 (SLC16A2) in humans lead to altered thyroid hormone levels and a severe neurodevelopmental disorder. Genetically engineered defect of the Mct8 gene in mice leads to similar thyroid hormone abnormalities but no obvious impairment of brain development or function. In this work we studied the relative role of the blood-brain barrier and the neuronal plasma cell membrane in the restricted access of T3 to the target neurons. To this end we compared the effects of low doses of T4 and T3 on cerebellar structure and gene expression in wild-type (Wt) and Mct8 null male mice [Mct8-/y, knockout (KO)] made hypothyroid during the neonatal period. We found that compared with Wt animals, T4 was considerably more potent than T3 in the Mct8KO mice, indicating a restricted access of T3, but not T4, to neurons after systemic administration in vivo. In contrast, T3 action in cultured cerebellar neurons was similar in...
Uploads
Papers by Juan Bernal