| 1. |
- Engblom, David, et al.
(författare)
-
Direct glucocorticoid receptor-Stat5 interaction in hepatocytes controls body size and maturation-related gene expression
- 2007
-
Ingår i: Genes & Development. - : Csh Cold Spring Harbor Laboratory Press. - 0890-9369 .- 1549-5477. ; 21:10, s. 1157-1162
-
Tidskriftsartikel (refereegranskat)abstract
- The glucocorticoid receptor regulates transcription through DNA binding as well as through cross-talk with other transcription factors. In hepatocytes, the glucocorticoid receptor is critical for normal postnatal growth. Using hepatocyte- specific and domain-selective mutations in the mouse we show that Stat5 in hepatocytes is essential for normal postnatal growth and that it mediates the growth- promoting effect of the glucocorticoid receptor through a direct interaction involving the N-terminal tetramerization domain of Stat5b. This interaction mediates a selective and unexpectedly extensive part of the transcriptional actions of these molecules since it controls the expression of gene sets involved in growth and sexual maturation.
|
|
| 2. |
- Khani, Sajjad, et al.
(författare)
-
Cold-induced expression of a truncated adenylyl cyclase 3 acts as rheostat to brown fat function
- 2024
-
Ingår i: Nature Metabolism. - 2522-5812. ; 6:6, s. 1053-1075
-
Tidskriftsartikel (refereegranskat)abstract
- Promoting brown adipose tissue (BAT) activity innovatively targets obesity and metabolic disease. While thermogenic activation of BAT is well understood, the rheostatic regulation of BAT to avoid excessive energy dissipation remains ill-defined. Here, we demonstrate that adenylyl cyclase 3 (AC3) is key for BAT function. We identified a cold-inducible promoter that generates a 5′ truncated AC3 mRNA isoform (Adcy3-at), whose expression is driven by a cold-induced, truncated isoform of PPARGC1A (PPARGC1A-AT). Male mice lacking Adcy3-at display increased energy expenditure and are resistant to obesity and ensuing metabolic imbalances. Mouse and human AC3-AT are retained in the endoplasmic reticulum, unable to translocate to the plasma membrane and lack enzymatic activity. AC3-AT interacts with AC3 and sequesters it in the endoplasmic reticulum, reducing the pool of adenylyl cyclases available for G-protein-mediated cAMP synthesis. Thus, AC3-AT acts as a cold-induced rheostat in BAT, limiting adverse consequences of cAMP activity during chronic BAT activation.
|
|
| 3. |
- Kornfeld, Jan-Wilhelm, et al.
(författare)
-
Variants in STAT5B Associate with Serum TC and LDL-C Levels
- 2011
-
Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 96:9, s. E1496-E1501
-
Tidskriftsartikel (refereegranskat)abstract
- Context: Known genetic variants influencing serum lipid levels do not adequately account for the observed population variability of these phenotypes. The GH/signal transducers and activators of transcription (STAT) signaling pathway is an evolutionary conserved system that exerts strong effects on metabolism, including that of lipids. Research Design and Methods: We analyzed the association of 11 single-nucleotide polymorphisms (SNP) spanning the STAT5B/STAT5A/STAT3 locus with serum lipid levels in six European populations (n = 5162 nondiabetic individuals). Results: After adjustment for age, sex, alcohol use, smoking, and body mass index, we identified STAT5B variants(rs8082391 and rs8064638) in novel association with total cholesterol (TC; P = 0.001 and P = 0.002) and low-density lipoprotein cholesterol (P = 0.002 and P = 0.004) levels. The minor alleles of these single-nucleotide polymorphisms were significantly enriched in hyperlipidemic individuals across the six discovery populations (P = 0.004 and P = 0.006). In transgenic mice deficient for hepatic STAT5A and STAT5B, reduced serum TC levels coincided with reduced hepatic cholesterol biosynthesis as demonstrated using gene expression profiling and pathway enrichment analysis. Conclusions: Genetic variants in STAT5B are associated with TC and low-density lipoprotein cholesterol levels among six populations. Mechanistically, STAT5B transcriptionally regulates hepatic cholesterol homeostasis.
|
|
| 4. |
- Mueller, Kristina M, et al.
(författare)
-
Impairment of Hepatic Growth Hormone and Glucocorticoid Receptor Signaling Causes Steatosis and Hepatocellular Carcinoma in Mice
- 2011
-
Ingår i: Hepatology. - : Wiley-Blackwell. - 0270-9139 .- 1527-3350. ; 54:4, s. 1398-1409
-
Tidskriftsartikel (refereegranskat)abstract
- Growth hormone (GH)-activated signal transducer and activator of transcription 5 (STAT5) and the glucocorticoid (GC)-responsive glucocorticoid receptor (GR) are important signal integrators in the liver during metabolic and physiologic stress. Their deregulation has been implicated in the development of metabolic liver diseases, such as steatosis and progression to fibrosis. Using liver-specific STAT5 and GR knockout mice, we addressed their role in metabolism and liver cancer onset. STAT5 single and STAT5/GR double mutants developed steatosis, but only double-mutant mice progressed to liver cancer. Mechanistically, STAT5 deficiency led to the up-regulation of prolipogenic sterol regulatory element binding protein 1 (SREBP-1) and peroxisome proliferator activated receptor gamma (PPAR-gamma) signaling. Combined loss of STAT5/GR resulted in GH resistance and hypercortisolism. The combination of both induced expression of adipose tissue lipases, adipose tissue lipid mobilization, and lipid flux to the liver, thereby aggravating STAT5-dependent steatosis. The metabolic dysfunctions in STAT5/GR compound knockout animals led to the development of hepatic dysplasia at 9 months of age. At 12 months, 35% of STAT5/GR-deficient livers harbored dysplastic nodules and similar to 60% hepatocellular carcinomas (HCCs). HCC development was associated with GH and insulin resistance, enhanced tumor necrosis factor alpha (TNF-alpha) expression, high reactive oxygen species levels, and augmented liver and DNA damage parameters. Moreover, activation of the c-Jun N-terminal kinase 1 (JNK1) and STAT3 was prominent. Conclusion: Hepatic STAT5/GR signaling is crucial for the maintenance of systemic lipid homeostasis. Impairment of both signaling cascades causes severe metabolic liver disease and promotes spontaneous hepatic tumorigenesis.
|
|
