Hepatic Inactivation of the Type 2 Deiodinase Confers Resistance to Alcoholic Liver Steatosis

A mouse with hepatocyte-specific deiodinase type II inactivation (Alb-D2KO) is resistant to diet-induced obesity, hepatic steatosis, and hypertriglyceridemia due to perinatal epigenetic modifications in the liver. This phenotype is linked to low levels of Zfp125, a hepatic transcriptional repressor that promotes liver steatosis by inhibiting genes involved in packaging and secretion of very-low-density lipoprotein.Here, we used chronic and binge ethanol (EtOH) in mice to cause liver steatosis.The EtOH treatment causes a 2.3-fold increase in hepatic triglyceride content; Zfp125 levels were approximately 50% higher in these animals. In contrast, Alb-D2KO mice did not develop EtOH-induced liver steatosis. They also failed to elevate Zfp125 to the same levels, despite being on the EtOH-containing diet for the same period of time. Their phenotype was associated with 1.3- to 2.9-fold up-regulation of hepatic genes involved in lipid transport and export that are normally repressed by Zfp125, that is, Mttp, Abca1, Ldlr, Apoc1, Apoc3, Apoe, Apoh, and Azgp1. Furthermore, genes involved in the EtOH metabolic pathway, that is, Aldh2 and Acss2, were also 1.6- to 3.1-fold up-regulated in Alb-D2KO EtOH mice compared with control animals kept on EtOH.EtOH consumption elevates expression of Zfp125. Alb-D2KO animals, which have lower levels of Zfp125, are much less susceptible to EtOH-induced liver steatosis

Early Developmental Disruption of Type 2 Deiodinase Pathway in Mouse Skeletal Muscle Does Not Impair Muscle Function

Background: Myogenesis is positively regulated by thyroid hormone (triiodothyronine [T3]), which is amplified by the type 2 deiodinase (D2) activation of thyroxine to T3. Global inactivation of the Dio2 gene impairs skeletal muscle (SKM) differentiation and regeneration in response to muscle injury. Given that newborn and adult mice with late developmental SKM Dio2 disruption do not develop a significant phenotype, it was hypothesized that D2 plays an early role in this process. Methods: This was tested in mice with SKM disruption of Dio2 driven by two early developmental promoters: MYF5 and MYOD. Results: MYF5 myoblasts in culture differentiate normally into myotubes, despite loss of almost all D2 activity. Dio2 mRNA levels in developing SKM obtained from MYF5-D2KO embryos (E18.5) were about 54% of control littermates, but the expression of the T3-responsive genes Myh1 and 7 and Atp2a1 and 2 were not affected. In MYF5-D2KO and MYOD-D2KO neonatal hind-limb muscle, the expression of Myh1 and 7 and Atp2a2 remained unaffected, despite 60-70% loss in D2 activity and/or mRNA. Only in MYOD-D2KO neonatal muscle was there a 40% reduction in Atp2a1 mRNA. Postnatal growth of both mouse models and SKM function as assessed by exercise capacity and measurement of muscle strength were normal. Furthermore, an analysis of the adult soleus revealed no changes in the expression of T3-responsive genes, except for an about 18% increase in MYOD-D2KO SOL Myh7 mRNA. Conclusion: Two mouse models of early developmental disruption of Dio2 in myocyte precursor exhibit no significant SKM phenotype.NIDDKBrazilian National Research Council (CNPq)American Thyroid Association (ATA)Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ)Rush Univ, Med Ctr, Div Endocrinol & Metab, 1735 W Harrison St,Suite 363,Cohn Bldg, Chicago, IL 60612 USAUniv Fed Rio de Janeiro, Biophys Inst, Rio De Janeiro, BrazilUniv Fed Rio de Janeiro, Sch Phys Educ & Sports, Rio De Janeiro, BrazilUniv Fed Rio de Janeiro, Nutr Inst Josue de Castro, Rio De Janeiro, BrazilUniv Fed Sao Paulo, Dept Translat Med, Sao Paulo, BrazilUniv Prebiteriana Mackenzie, Dev Disorders Program, Ctr Biol & Hlth Sci, Sao Paulo, BrazilHungarian Acad Sci, Inst Expt Med, Dept Endocrine Neurobiol, Budapest, HungaryUniv Fed Sao Paulo, Dept Translat Med, Sao Paulo, BrazilNIDDK: R01 65055ACNPq: 202189/2011-2American Thyroid Association (ATA): M1301627Web of Scienc

Type 2 Deiodinase Disruption in Astrocytes Results in Anxiety-Depressive-Like Behavior in Male Mice

Millions of levothyroxine-treated hypothyroid patients complain of impaired cognition despite normal TSH serum levels. This could reflect abnormalities in the type 2 deiodinase (D2)-mediated T-4-to-T-3 conversion, given their much greater dependence on the D2 pathway for T-3 production. T-3 normally reaches the brain directly from the circulation or is produced locally by D2 in astrocytes. Here we report that mice with astrocyte-specific Dio2 inactivation (Astro-D2KO) have normal serum T-3 but exhibit anxiety-depression-like behavior as found in open field and elevated plus maze studies and when tested for depression using the tail-suspension and the forced-swimming tests. Remarkably, 4 weeks of daily treadmill exercise sessions eliminated this phenotype. Microarray gene expression profiling of the Astro-D2KO hippocampi identified an enrichment of three gene sets related to inflammation and impoverishment of three gene sets related to mitochondrial function and response to oxidative stress. Despite normal neurogenesis, the Astro-D2KO hippocampi exhibited decreased expression of four of six known to be positively regulated genes by T-3, ie, Mbp (similar to 43%), Mag (similar to 34%), Hr (similar to 49%), and Aldh1a1 (similar to 61%) and increased expression of 3 of 12 genes negatively regulated by T-3, ie, Dgkg (similar to 17%), Syce2 (similar to 26%), and Col6a1 (similar to 3-fold) by quantitative real-time PCR. Notably, in Astro-D2KO animals, there was also a reduction in mRNA levels of genes known to be affected in classical animal models of depression, ie, Bdnf (similar to 18%), Ntf3 (similar to 43%), Nmdar (similar to 26%), and GR (similar to 20%), which were also normalized by daily exercise sessions. These findings suggest that defects in Dio2 expression in the brain could result in mood and behavioral disorders.National Institute of Diabetes and Digestive and Kidney Diseases [R01 65055]Hungarian Brain Research Program Grant [NAP A I/3-4]Coordination for the Improvement of Higher Education Personnel Grant, Coordination for the Improvement of Higher Education Personnel (CAPES), BrazilRush Univ, Med Ctr, Div Endocrinol & Metab, 1735 West Harrison St, Chicago, IL 60612 USAUniv Fed Sao Paulo, Dept Translat Med, BR-04039002 Sao Paulo, SP, BrazilUniv Fed Rio de Janeiro, Inst Biophys, BR-21941599 Rio De Janeiro, RJ, BrazilUniv Fed Rio de Janeiro, Sch Phys Educ & Sports, BR-21941599 Rio De Janeiro, RJ, BrazilUniv Fed Sao Paulo, Dept Clin Endocrinol, BR-04039032 Sao Paulo, SP, BrazilUniv Prebiteriana Mackenzie, Ctr Biol Sci & Hlth, Dev Disorders Program, Rua Consolacao 930, BR-01302900 Sao Paulo, SP, BrazilHungarian Acad Sci, Inst Expt Med, Dept Endocrine Neurobiol, H-1083 Budapest, HungaryTufts Med Ctr, Tupper Res Inst, Div Endocrinol Diabet & Metab, Dept Med, Boston, MA 02111 USAUniv Paulista, Grad Program Dent, Grad Program Environm & Expt Pathol, BR-04026002 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Translat Med, BR-04039002 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Clin Endocrinol, BR-04039032 Sao Paulo, SP, BrazilNIDDK:R01 65055Web of Scienc

Thyroid hormone activation by type2 deiodinase mediates exercise-induced peroxisome proliferator-activated receptor-gamma coactivator-1 alpha expression in skeletal muscle

Key points In skeletal muscle, physical exercise and thyroid hormone mediate the peroxisome proliferator-activated receptor- coactivator-1 (PGC-1a) expression that is crucial to skeletal muscle mitochondrial function. The expression of type 2 deiodinase (D2), which activates thyroid hormone in skeletal muscle is upregulated by acute treadmill exercise through a -adrenergic receptor-dependent mechanism. Pharmacological block of D2 or disruption of the Dio2 gene in skeletal muscle fibres impaired acute exercise-induced PGC-1a expression.Dio2 disruption also impaired muscle PGC-1a expression and mitochondrial citrate synthase activity in chronically exercised mice. AbstractThyroid hormone promotes expression of peroxisome proliferator-activated receptor- coactivator-1 (PGC-1a), which mediates mitochondrial biogenesis and oxidative capacity in skeletal muscle (SKM). Skeletal myocytes express the type 2 deiodinase (D2), which generates 3,5,3-triiodothyronine (T-3), the active thyroid hormone. To test whether D2-generated T-3 plays a role in exercise-induced PGC-1a expression, male rats and mice with SKM-specific Dio2 inactivation (SKM-D2KO or MYF5-D2KO) were studied. An acute treadmill exercise session (20min at 70-75% of maximal aerobic capacity) increased D2 expression/activity (1.5- to 2.7-fold) as well as PGC-1a mRNA levels (1.5- to 5-fold) in rat soleus muscle and white gastrocnemius muscle and in mouse soleus muscle, which was prevented by pretreatment with 1mg(100g body weight)(-1) propranolol or 6mg(100g body weight)(-1) iopanoic acid (5.9- vs. 2.8-foldP<0.05), which blocks D2 activity . In the SKM-D2KO mice, acute treadmill exercise failed to induce PGC-1a fully in soleus muscle (1.9-vs. 2.8-foldP<0.05), and in primary SKM-D2KO myocytes there was only a limited PGC-1a response to 1m forskolin (2.2- vs. 1.3-foldP<0.05). Chronic exercise training (6weeks) increased soleus muscle PGC-1a mRNA levels (approximate to 25%) and the mitochondrial enzyme citrate synthase (approximate to 20%). In contrast, PGC-1a expression did not change and citrate synthase decreased by approximate to 30% in SKM-D2KO mice. The soleus muscle PGC-1a response to chronic exercise was also blunted in MYF5-D2KO mice. In conclusion, acute treadmill exercise increases SKM D2 expression through a -adrenergic receptor-dependent mechanism. The accelerated conversion of T-4 to T-3 within myocytes mediates part of the PGC-1a induction by treadmill exercise and its downstream effects on mitochondrial function.National Institute of Diabetes and Digestive and Kidney DiseasesBrazilian National Research Council (CNPq)Carlos Chagas Filho Foundation for Research Support in Rio de Janeiro (FAPERJ)American Thyroid Association (ATA)Hungarian Research Fund (OTKA)Coordination for the Improvement of Higher Education Personnel (CAPES)Rush Univ, Med Ctr, Div Endocrinol & Metab, Chicago, IL 60612 USAUniv Fed Sao Paulo, Dept Translat Med, Sao Paulo, BrazilUniv Fed Rio de Janeiro, Inst Biophys Carlos Chagas Filho, BR-21941 Rio De Janeiro, BrazilUniv Fed Rio de Janeiro, Sch Phys Educ & Sports, BR-21941 Rio De Janeiro, BrazilUniv Miami, Miller Sch Med, Div Endocrinol Diabet & Metab, Miami, FL 33136 USAUniv Prebiteriana Mackenzie, Dev Disorders Program, Ctr Biol & Hlth Sci, Sao Paulo, BrazilHungarian Acad Sci, Dept Endocrine Neurobiol, Inst Expt Med, Budapest, HungaryUniv Fed Sao Paulo, Dept Translat Med, Sao Paulo, BrazilNIH: R01 65055ATA: M1301627OTKA: K109415Web of Scienc

The Foxo1-Inducible Transcriptional Repressor Zfp125 Causes Hepatic Steatosis and Hypercholesterolemia

Liver-specific disruption of the type 2 deiodinase gene (Alb-D2KO) results in resistance to both diet-induced obesity and liver steatosis in mice. Here, we report that this is explained by an similar to 60% reduction in liver zinc-finger protein-125 (Zfp125) expression. Zfp125 is a Foxo1-inducible transcriptional repressor that causes lipid accumulation in the AML12 mouse hepatic cell line and liver steatosis in mice by reducing liver secretion of triglycerides and hepatocyte efflux of cholesterol. Zfp125 acts by repressing 18 genes involved in lipoprotein structure, lipid binding, and transport. The ApoE promoter contains a functional Zfp125-binding element that is also present in 17 other lipid-related genes repressed by Zfp125. While liver-specific knockdown of Zfp125 causes an "Alb-D2KO-like'' metabolic phenotype, liver-specific normalization of Zfp125 expression in Alb-D2KO mice rescues the phenotype, restoring normal susceptibility to diet-induced obesity, liver steatosis, and hypercholesterolemia.NIDDKEUHungarian Brain Research ProgramFundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Coordenadoria de Apoio a Pesquisa (CAPES), BrazilRush Univ, Med Ctr, Div Endocrinol & Metab, Chicago, IL 60612 USAUniv Fed Sao Paulo, Program Translat Med, Sao Paulo, BrazilUniv Illinois, Coll Med, Dept Med, Sect Endocrinol Diabet & Metab, Chicago, IL USARush Univ, Div Digest Dis & Nutr, Med Ctr, Chicago, IL 60612 USAHarvard Med Sch, Joslin Diabet Ctr, Boston, MA USAUniv Prebiteriana Mackenzie, Ctr Biol Sci & Hlth, Dev Disorders Program, Sao Paulo, BrazilHungarian Acad Sci, Inst Expt Med, Dept Endocrine Neurobiol, Budapest, HungaryUniv Fed Sao Paulo, Program Translat Med, Sao Paulo, BrazilNIDDK: DK65055, R01DK106193, P30DK036836EU: 666869Hungarian Brain Research Program: KTIA_13_NAP_A_I/4FAPESP: 2011/21847-6Web of Scienc

Type 2 Deiodinase Disruption in Astrocytes Results in Anxiety-Depressive-Like Behavior in Male Mice

Millions of levothyroxine-treated hypothyroid patients complain of impaired cognition despite normal TSH serum levels. This could reflect abnormalities in the type 2 deiodinase (D2)-mediated T(4)-to-T(3) conversion, given their much greater dependence on the D2 pathway for T(3) production. T(3) normally reaches the brain directly from the circulation or is produced locally by D2 in astrocytes. Here we report that mice with astrocyte-specific Dio2 inactivation (Astro-D2KO) have normal serum T(3) but exhibit anxiety-depression-like behavior as found in open field and elevated plus maze studies and when tested for depression using the tail-suspension and the forced-swimming tests. Remarkably, 4 weeks of daily treadmill exercise sessions eliminated this phenotype. Microarray gene expression profiling of the Astro-D2KO hippocampi identified an enrichment of three gene sets related to inflammation and impoverishment of three gene sets related to mitochondrial function and response to oxidative stress. Despite normal neurogenesis, the Astro-D2KO hippocampi exhibited decreased expression of four of six known to be positively regulated genes by T(3), ie, Mbp (∼43%), Mag (∼34%), Hr (∼49%), and Aldh1a1 (∼61%) and increased expression of 3 of 12 genes negatively regulated by T(3), ie, Dgkg (∼17%), Syce2 (∼26%), and Col6a1 (∼3-fold) by quantitative real-time PCR. Notably, in Astro-D2KO animals, there was also a reduction in mRNA levels of genes known to be affected in classical animal models of depression, ie, Bdnf (∼18%), Ntf3 (∼43%), Nmdar (∼26%), and GR (∼20%), which were also normalized by daily exercise sessions. These findings suggest that defects in Dio2 expression in the brain could result in mood and behavioral disorders

Type 2 deiodinase polymorphism causes ER stress and hypothyroidism in the brain

Levothyroxine (LT4) is a form of thyroid hormone used to treat hypothyroidism. In the brain, T4 is converted to the active form T3 by type 2 deiodinase (D2). Thus, it is intriguing that carriers of the Thr92Ala polymorphism in the D2 gene ( DIO2 ) exhibit clinical improvement when liothyronine (LT3) is added to LT4 therapy. Here, we report that D2 is a cargo protein in ER Golgi intermediary compartment (ERGIC) vesicles, recycling between ER and Golgi. The Thr92-to-Ala substitution (Ala92-D2) caused ER stress and activated the unfolded protein response (UPR). Ala92-D2 accumulated in the trans-Golgi and generated less T3, which was restored by eliminating ER stress with the chemical chaperone 4-phenyl butyric acid (4-PBA). An Ala92-Dio2 polymorphism–carrying mouse exhibited UPR and hypothyroidism in distinct brain areas. The mouse refrained from physical activity, slept more, and required additional time to memorize objects. Enhancing T3 signaling in the brain with LT3 improved cognition, whereas restoring proteostasis with 4-PBA eliminated the Ala92-Dio2 phenotype. In contrast, primary hypothyroidism intensified the Ala92-Dio2 phenotype, with only partial response to LT4 therapy. Disruption of cellular proteostasis and reduced Ala92-D2 activity may explain the failure of LT4 therapy in carriers of Thr92Ala-DIO2