Genetically programmed changes in transcription of the novel progranulin regulator.

Progranulin is a glycoprotein marking chronic inflammation in obesity and type 2 diabetes. Previous studies suggested PSRC1 (proline and serine rich coiled-coil 1) to be a target of genetic variants associated with serum progranulin levels. We aimed to identify potentially functional variants and characterize their role in regulation of PSRC1. Phylogenetic module complexity analysis (PMCA) prioritized four polymorphisms (rs12740374, rs629301, rs660240, rs7528419) altering transcription factor binding sites with an overall score for potential regulatory function of Sall > 7.0. The effects of these variants on transcriptional activity and binding of transcription factors were tested by luciferase reporter and electrophoretic mobility shift assays (EMSA). In parallel, blood DNA promoter methylation of two regions was tested in subjects with a very high (N = 100) or a very low (N = 100) serum progranulin. Luciferase assays revealed lower activities in vectors carrying the rs629301-A compared with the C allele. Moreover, EMSA indicated a different binding pattern for the two rs629301 alleles, with an additional prominent band for the A allele, which was finally confirmed with the supershift for the Yin Yang 1 transcription factor (YY1). Subjects with high progranulin levels manifested a significantly higher mean DNA methylation (P < 1 × 10-7) in one promoter region, which was in line with a significantly lower PSRC1 mRNA expression levels in blood (P = 1 × 10-3). Consistently, rs629301-A allele was associated with lower PSRC1 mRNA expression (P < 1 × 10-7). Our data suggest that the progranulin-associated variant rs629301 modifies the transcription of PSRC1 through alteration of YY1 binding capacity. DNA methylation studies further support the role of PSRC1 in regulation of progranulin serum levels. KEY MESSAGES: PSRC1 (proline and serine rich coiled-coil 1) SNPs are associated with serum progranulin levels. rs629301 regulates PSRC1 expression by affecting Yin Yang 1 transcription factor (YY1) binding. PSRC1 is also epigenetically regulated in subjects with high progranulin levels.

The Effects of Thyroid Hormones on Gene Expression of Acyl-Coenzyme A Thioesterases in Adipose Tissue and Liver of Mice.

BACKGROUND: Thyroid hormones (TH) exert pleiotropic effects on glucose and lipid homeostasis. However, it is as yet unclear how TH regulate lipid storage and utilization in order to adapt to metabolic needs. Acyl-CoA thioesterases (ACOTs) have been proposed to play a regulatory role in the metabolism of fatty acids. OBJECTIVES: We investigated the interaction between thyroid dysfunction and Acot expression in adipose tissues and livers of thyrotoxic and hypothyroid mice. METHODS: Ten-week-old female C57BL/6NTac mice (n = 10/group) were made hyperthyroid by the application of L-thyroxine (2 µg/ml in drinking water) for 4 weeks. Hypothyroidism was induced in 10-week-old mice by feeding an iodine-free chow supplemented with 0.15% PTU for 4 weeks. We measured mRNA expression levels of Acot8, 11 and 13 in the liver and epididymal and inguinal white and brown adipose tissues (BAT). Furthermore, we investigated hepatic Acot gene expression in TRα- and TRß-deficient mice. RESULTS: We showed that the expression of Acot8, 11 and 13 is predominantly stimulated by a thyrotoxic state in the epididymal white adipose tissue. In contrast, hypothyroidism predominantly induces the expression of Acot8 in BAT in comparison with BAT of thyrotoxic and euthyroid mice (p < 0.01). However, no significant changes in Acot expression were observed in inguinal white adipose tissue. In liver, Acot gene expression is collectively elicited by a thyrotoxic state. CONCLUSIONS: These data suggest that ACOTs are targets of TH and are likely to influence 3,5,3'-triiodo-L-thyronine-orchestrated mechanisms of lipid uptake, storage and utilization to adapt the regulation of metabolic demands.