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Background and Objectives: Perilipins 1-5 (PLIN) are lipid droplet-associated proteins that participate in regulating lipid storage and metabolism, and the PLIN5 isoform is known to form a nuclear complex with peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α) to regulate lipid metabolism gene expression. However, the changes in PLIN isoforms' expression in response to pregnancy-induced cardiac hypertrophy are not thoroughly studied. The aim of this study was to quantify the mRNA expression of PLIN isoforms and PGC-1α along with total triacylglycerol (TAG) and cholesterol levels during late pregnancy and the postpartum period in the rat left ventricle. Materials and Methods: Female Sprague-Dawley rats were divided into three groups: non-pregnant, late pregnancy, and postpartum. The mRNA and protein levels were evaluated using quantitative RT-PCR and Western blotting, respectively. TAG and total cholesterol content were evaluated using commercial colorimetric methods. Results: The expression of mRNAs for PLIN1, 2, and 5 increased during pregnancy and the postpartum period. PGC-1α mRNA and protein expression increased during pregnancy and the postpartum period. Moreover, TAG and total cholesterol increased during pregnancy and returned to basal levels after pregnancy. Conclusions: Our results demonstrate that pregnancy upregulates differentially the expression of PLIN isoforms along with PGC-1α, suggesting that together they might be involved in the regulation of the lipid metabolic shift induced by pregnancy.

Hypoxia inducible factor-1 (HIF-1) is a transcriptional factor that induces genes involved in glucose metabolism. HIF-1 is formed by a regulatory α-subunit (HIF-1α) and a constitutive β-subunit (HIF-1β). The white spot syndrome virus (WSSV) induces a shift in glucose metabolism and oxidative stress. HIF-1α is associated with the induction of metabolic changes in tissues of WSSV-infected shrimp. However, the contributions of HIF-1 to viral load and antioxidant responses in WSSV-infected shrimp have been not examined. In this study, the effect of HIF-1 silencing on viral load and the expression and activity of antioxidant enzymes (superoxide dismutase-SOD, glutathione S-transferase-GST, and catalase) along with oxidative damage (lipid peroxidation and protein carbonyl) in tissues of white shrimp infected with the WSSV were studied. The viral load increased in hepatopancreas and muscle after WSSV infection, and the accumulative mortality was of 100% at 72 h post-infection. The expression and activity of SOD, catalase, and GST decreased in each tissue evaluated after WSSV infection. Protein carbonyl concentrations increased in each tissue after WSSV infection, while lipid peroxidation increased in hepatopancreas, but not in muscle. Silencing of HIF-1α decreased the WSSV viral load in hepatopancreas and muscle of infected shrimp along with shrimp mortality. Silencing of HIF-1α ameliorated the antioxidant response in a tissue-specific manner, which translated to a decrease in oxidative damage. These results suggest that HIF-1 is essential for restoring the antioxidant response, which counters the oxidative injury associated with WSSV infection.

Food deprivation in mammals is typically associated with reduced thyroid hormone (TH) concentrations and deiodinase content and activity to suppress metabolism. However, in prolonged-fasted, metabolically active elephant seal pups, TH levels are maintained, if not elevated. The functional relevance of this apparent paradox is unknown and demonstrates variability in the regulation of TH levels, metabolism and function in food-deprived mammals. To address our hypothesis that cellular TH-mediated activity is upregulated with fasting duration, we quantified the mRNA expression and protein content of adipose and muscle deiodinase type I (DI1) and type II (DI2), and TH receptor beta-1 (THrß-1) after 1, 3 and 7 weeks of fasting in northern elephant seal pups (N=5-7 per week). Fasting did not decrease the concentrations of plasma thyroid stimulating hormone, total triiodothyronine (tT3), free T3, total thyroxine (tT4) or free T4, suggesting that the hypothalamic-pituitary-thyroid axis is not suppressed, but rather maintained during fasting. Mean mRNA expression of adipose DI1 and DI2 increased threefold and fourfold, respectively, and 20- and 30-fold, respectively, in muscle. With the exception of adipose DI1, protein expression of adipose DI2 and muscle DI1 and DI2 increased twofold to fourfold. Fasting also increased adipose (fivefold) and muscle (fourfold) THrß-1 mRNA expression, suggesting that the mechanisms mediating cellular TH activity are upregulated with prolonged fasting. The data demonstrate a unique, atypical mechanism of TH activity and regulation in mammals adapted to prolonged food deprivation in which the potential responsiveness of peripheral tissues and cellular TH activity are increased, which may contribute to their lipid-based metabolism. [ABSTRACT FROM AUTHOR]

Abstract: Hypoxia inducible factors (HIFs) are important regulators of energy homeostasis and cellular adaptation to low oxygen conditions. Northern elephant seals are naturally adapted to prolonged periods (1–2months) of food deprivation (fasting) which result in metabolic changes that may activate HIF-1. However, the effects of prolonged fasting on HIFs are not well defined. We obtained the full-length cDNAs of HIF-1α and HIF-2α, and partial cDNA of HIF-3α in northern elephant seal pups. We also measured mRNA and nuclear protein content of HIF-1α, -2α, -3α in muscle and adipose during prolonged fasting (1, 3, 5 & 7weeks), along with mRNA expression of HIF-mediated genes, LDH and VEGF. HIF-1α, -2α and -3α are 2595, 2852 and 1842bp and encode proteins of 823, 864 and 586 amino acid residues with conserved domains needed for their function (bHLH and PAS) and regulation (ODD and TAD). HIF-1α and -2α mRNA expression increased 3- to 5-fold after 7weeks of fasting in adipose and muscle, whereas HIF-3α increased 5-fold after 7weeks of fasting in adipose. HIF-2α protein expression was detected in nuclear fractions from adipose and muscle, increasing approximately 2-fold, respectively with fasting. Expression of VEGF increased 3-fold after 7weeks in adipose and muscle, whereas LDH mRNA expression increased 12-fold after 7weeks in adipose. While the 3 HIFα genes are expressed in muscle and adipose, only HIF-2α protein was detectable in the nucleus suggesting that HIF-2α may contribute more significantly in the up-regulation of genes involved in the metabolic adaptation during fasting in the elephant seal. [Copyright &y& Elsevier]

Abstract: Hypoxia inducible factor 1 (HIF-1) is a key transcription factor that regulates a variety of molecular responses to hypoxia. Some marine crustaceans experience changes of oxygen tension in their aquatic environment, but knowledge about the function and expression of HIF-1 is very limited. HIF-1 is a heterodimer composed by α and β subunits. We report the complete cDNA sequences of HIF-1α and HIF-1β from the white shrimp Litopenaeus vannamei. HIF-1α (LvHIF-1α) is 3672bp and codes for 1050 amino acids, while HIF-1β is 2135bp (LvHIF-1β) and 608 amino acids. Both, the α and β subunits have the helix-loop-helix (bHLH) and PAS domains. HIF-1α also has the oxygen dependent degradation (ODD) and the C-terminal transactivation domain (C-TAD), important for regulation in normoxia. Phylogenetic analyses of the proteins indicate separation of invertebrates from vertebrates. Large differences of HIF-1α and HIF-1β transcripts abundance were detected in gills, hepatopancreas and muscle under normoxia (6mg/L dissolved oxygen, DO) and hypoxia (2.5 and 1.5mg/L DO). HIF-1α was more abundant in gills and HIF-1β in hepatopancreas. Large changes in response to hypoxia were detected for HIF-1α in gills, while HIF-1β remained fairly constant. Glucose and lactate in hemolymph increased rapidly in hypoxia in all cases and up to 4.7 and 5.0-fold, respectively, in response to 1.5mg/L DO for 1h. [Copyright &y& Elsevier]

Crustaceans overcome osmotic disturbances by regulating their intracellular concentration of ions and osmolytes. Glycine betaine (GB), an osmolyte accumulated in response to hyperosmotic stress, is synthesized by betaine aldehyde dehydrogenase (BADH EC 1.2.1.8) through the oxidation of betaine aldehyde. A partial BADH cDNA sequence from the white shrimp Litopenaeus vannamei was obtained and its organ-specific expression during osmotic stress (low and high salinity) was evaluated. The partial BADH cDNA sequence (LvBADH) is 1103 bp long and encodes an open reading frame for 217 protein residues. The amino acid sequence of LvBADH is related to that of other BADHs, TMABA-DH and ALDH9 from invertebrate and vertebrate homologues, and includes the essential domains of their function and regulation. LvBADH activity and mRNA expression were detected in the gills, hepatopancreas and muscle with the highest levels in the hepatopancreas. LvBADH mRNA expression increased 2–3-fold in the hepatopancreas and gills after 7 days of osmotic variation (25 and 40 ppt). In contrast, LvBADH mRNA expression in muscle decreased 4-fold and 15-fold after 7 days at low and high salinity, respectively. The results indicate that LvBADH is ubiquitously expressed, but its levels are organ-specific and regulated by osmotic stress, and that LvBADH is involved in the cellular response of crustaceans to variations in environmental salinity. [ABSTRACT FROM AUTHOR]

Hypoxia inducible factor-1 (HIF-1) is a transcriptional factor that induces genes involved in glucose metabolism. HIF-1 is formed by a regulatory α-subunit (HIF-1α) and a constitutive β-subunit (HIF-1β). The white spot syndrome virus (WSSV) induces a shift in glucose metabolism and oxidative stress. HIF-1α is associated with the induction of metabolic changes in tissues of WSSV-infected shrimp. However, the contributions of HIF-1 to viral load and antioxidant responses in WSSV-infected shrimp have been not examined. In this study, the effect of HIF-1 silencing on viral load and the expression and activity of antioxidant enzymes (superoxide dismutase-SOD, glutathione S-transferase-GST, and catalase) along with oxidative damage (lipid peroxidation and protein carbonyl) in tissues of white shrimp infected with the WSSV were studied. The viral load increased in hepatopancreas and muscle after WSSV infection, and the accumulative mortality was of 100% at 72 h post-infection. The expression and activity of SOD, catalase, and GST decreased in each tissue evaluated after WSSV infection. Protein carbonyl concentrations increased in each tissue after WSSV infection, while lipid peroxidation increased in hepatopancreas, but not in muscle. Silencing of HIF-1α decreased the WSSV viral load in hepatopancreas and muscle of infected shrimp along with shrimp mortality. Silencing of HIF-1α ameliorated the antioxidant response in a tissue-specific manner, which translated to a decrease in oxidative damage. These results suggest that HIF-1 is essential for restoring the antioxidant response, which counters the oxidative injury associated with WSSV infection. [ABSTRACT FROM AUTHOR]