scholarly journals Polymerase I and Transcript Release Factor Regulates Lipolysis via a Phosphorylation-Dependent Mechanism

Diabetes ◽  
2011 ◽  
Vol 60 (3) ◽  
pp. 757-765 ◽  
Author(s):  
Nabila Aboulaich ◽  
Patricia C. Chui ◽  
John M. Asara ◽  
Jeffrey S. Flier ◽  
Eleftheria Maratos-Flier
Keyword(s):  
Release Factor ◽  
Polymerase I ◽  
Dependent Mechanism

scholarly journals Polymerase I and transcript release factor (PTRF) regulates adipocyte differentiation and determines adipose tissue expandability

2014 ◽  
Vol 28 (8) ◽  
pp. 3769-3779 ◽  
Author(s):  
Sergio Perez‐Diaz ◽  
Lance A. Johnson ◽  
Robert M. DeKroon ◽  
Jose M. Moreno‐Navarrete ◽  
Oscar Alzate ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Adipocyte Differentiation ◽  
Release Factor ◽  
Polymerase I ◽  
Adipose Tissue Expandability

scholarly journals Vectorial proteomics reveal targeting, phosphorylation and specific fragmentation of polymerase I and transcript release factor (PTRF) at the surface of caveolae in human adipocytes

2004 ◽  
Vol 383 (2) ◽  
pp. 237-248 ◽  
Author(s):  
Nabila ABOULAICH ◽  
Julia P. VAINONEN ◽  
Peter STRÅLFORS ◽  
Alexander V. VENER
Keyword(s):  
Plasma Membranes ◽  
Leucine Zipper ◽  
Amine Oxidase ◽  
Cleavage Sites ◽  
Release Factor ◽  
Human Adipocytes ◽  
Nuclear Localization Signals ◽  
Membrane Surfaces ◽  
Specific Proteins ◽  
Polymerase I

Caveolae, the specialized invaginations of plasma membranes, formed sealed vesicles with outwards-orientated cytosolic surface after isolation from primary human adipocytes. This morphology allowed differential, vectorial identification of proteins at the opposite membrane surfaces by proteolysis and MS. Extracellular-exposed caveolae-specific proteins CD36 and copper-containing amine oxidase were concealed inside the vesicles and resisted trypsin treatment. The cytosol-orientated caveolins were efficiently digested by trypsin, producing peptides amenable to direct MS sequencing. Isolation of peripheral proteins associated with the cytosolic surface of caveolae revealed a set of proteins that contained nuclear localization signals, leucine-zipper domains and PEST (amino acid sequence enriched in proline, glutamic acid, serine and threonine) domains implicated in regulation by proteolysis. In particular, PTRF (polymerase I and transcript release factor) was found as a major caveolae-associated protein and its co-localization with caveolin was confirmed by immunofluorescence confocal microscopy. PTRF was present at the surface of caveolae in the intact form and in five different truncated forms. Peptides (44 and 45 amino acids long) comprising both the PEST domains were sequenced by nanospray-quadrupole-time-of-flight MS from the full-length PTRF, but were not found in the truncated forms of the protein. Two endogenous cleavage sites corresponding to calpain specificity were identified in PTRF; one of them was in a PEST domain. Both cleavage sites were flanked by mono- or diphosphorylated sequences. The phosphorylation sites were localized to Ser-36, Ser-40, Ser-365 and Ser-366 in PTRF. Caveolae of human adipocytes are proposed to function in targeting, relocation and proteolytic control of PTRF and other PEST-domain-containing signalling proteins.

Cavin 1 function does not follow caveolar morphology

2015 ◽  
Vol 308 (12) ◽  
pp. C1023-C1030 ◽  
Author(s):  
Tobias Timmel ◽  
Séverine Kunz ◽  
Franziska Seifert ◽  
Markus Schuelke ◽  
Simone Spuler
Keyword(s):  
Electron Microscopy ◽  
Cholera Toxin ◽  
Proper Function ◽  
Release Factor ◽  
Toxin B ◽  
Anatomic Structure ◽  
Cholera Toxin B ◽  
B Uptake ◽  
Polymerase I ◽  
Functional Analyses

The function of caveolae, small invaginations of the plasma membrane, remains a matter of debate. We discuss endocytosis and compartmentalization of metabolic and signaling pathways. Caveolin 3 (CAV3) and polymerase I and transcript release factor (PTRF) are important proteins that ensure shaping of caveolae in muscle cells. We investigated caveolae morphologically by electron microscopy in myotubes obtained from patients with CAV3 mutations and performed functional analyses in fibroblasts from a patient with a mutation in PTRF. Despite the complete clinical picture of a caveolinopathy, we found that caveolae in the CAV3-deficient myotubes were normal in shape and number. Furthermore, we found a difference in uptake of cholera toxin B between PTRF-deficient fibroblasts devoid of caveolae and normal fibroblasts. However, after caveolae were rescued by transfection of PTRF, cholera toxin B uptake did not normalize. We conclude that the presence of caveolae as an anatomic structure is not sufficient to ensure their proper function. Alternatively, the functional properties assigned to caveolae might be mediated by different mechanisms that have yet to be resolved.

scholarly journals Caveolar Dysfunction and Lipodystrophies

2021 ◽  
Author(s):  
Nivedita Patni ◽  
Ra Hegele ◽  
Abhimanyu Garg
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Autosomal Recessive ◽  
Autosomal Recessive Disorder ◽  
Release Factor ◽  
Metabolic Complications ◽  
Caveolin 1 ◽  
Total Absence ◽  
Genetic Subtypes ◽  
Polymerase I

Congenital generalized lipodystrophy (CGL) is a rare, heterogeneous, autosomal recessive disorder characterized by near total absence of body fat with increased muscularity noticed at birth or in early infancy. Four distinct genetic subtypes of CGL have been reported to date. Types 1 and 2 are caused by biallelic variants in the 1-acylglycerol-3-phosphate-O-acyltransferase 2 (AGPAT2) and Berardinelli-Seip Congenital Lipodystrophy 2 (BSCL2) genes, respectively, and are the most common subtypes (1). Types 3 and 4 are extremely rare and are caused by biallelic variants in the caveolin 1 (CAV1) (2), and Caveolae Associated Protein-1 (CAVIN1; also known as polymerase I and transcript release factor (PTRF)]) genes (3), respectively. Patients with all CGL subtypes are predisposed to metabolic complications of insulin resistance, such as diabetes mellitus, hypertriglyceridemia and hepatic steatosis; however, each subtype presents with some unique clinical features.

scholarly journals PTRF (polymerase I and transcript-release factor) is tissue-specific and interacts with the BFCOL1 (binding factor of a type-I collagen promoter) zinc-finger transcription factor which binds to the two mouse type-I collagen gene promoters

2000 ◽  
Vol 347 (1) ◽  
pp. 55-59 ◽  
Author(s):  
Tadao HASEGAWA ◽  
Akihide TAKEUCHI ◽  
Osamu MIYAISHI ◽  
Hengyi XIAO ◽  
Jalin MAO ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Zinc Finger ◽  
Type I Collagen ◽  
Rna Polymerase I ◽  
Proximal Promoter ◽  
Type I ◽  
Release Factor ◽  
Binding Factor ◽  
Polymerase I ◽  
Collagen Promoter

We have used the yeast two-hybrid system to clone the protein that interacts with the BFCOL1 (binding factor of a type-I collagen promoter) zinc-finger transcription factor that was cloned previously as the factor that binds to the two mouse proximal promoters of the type-I collagen genes. We utilized as bait the N-terminal domain of BFCOL1 that includes the zinc-finger DNA-binding domain. One cDNA contained a potential open reading frame for a polypeptide of 392 amino acids and was identical to PTRF (polymerase I and transcript-release factor), which is involved in transcription termination of the RNA polymerase I reaction. Northern-blot analysis revealed that the pattern of mRNA expression was similar to that of the type-I collagen gene. In addition, we detected the mRNA expression only in a fibroblast cell line and two bone cell lines, but not in other blood and neuronal cell lines. Recombinant protein was shown to enhance the binding of BFCOL1 to its binding site in the mouse proα2(I) collagen proximal promoter in vitro. The transient-transfection experiment showed that PTRF had a suppressive effect on the mouse proα2(I) collagen proximal promoter activity. We speculate that PTRF might play a role in the RNA polymerase II reaction as well as that of RNA polymerase I.

scholarly journals Caveolin-1 Induces Formation of Membrane Tubules That Sense Actomyosin Tension and Are Inhibited by Polymerase I and Transcript Release Factor/Cavin-1

2010 ◽  
Vol 21 (13) ◽  
pp. 2226-2240 ◽  
Author(s):  
Prakhar Verma ◽  
Anne G. Ostermeyer-Fay ◽  
Deborah A. Brown
Keyword(s):  
Cancer Cells ◽  
Actin Filaments ◽  
Release Factor ◽  
Cortical Actin ◽  
Functional Interaction ◽  
Tubule Formation ◽  
Normal Cells ◽  
Caveolin 1 ◽  
Membrane Tubules ◽  
Polymerase I

Caveolin-1 and caveolae are often lost in cancer. We found that levels of caveolin-1 and polymerase I and transcript release factor (PTRF)/cavin-1 correlated closely in a panel of cancer and normal cells. Caveolin-1 reexpression in cancer cells lacking both proteins induced formation of long membrane tubules rarely seen in normal cells. PTRF/cavin-1 inhibited tubule formation when coexpressed with caveolin-1 in these cells, whereas suppression of PTRF/cavin-1 expression in cells that normally expressed both genes stimulated tubule formation by endogenous caveolin-1. Caveolin-1 tubules shared several features with previously described Rab8 tubules. Coexpressed Rab8 and caveolin-1 labeled the same tubules (as did EHD proteins), and synergized to promote tubule formation, whereas a dominant-interfering Rab8 mutant inhibited caveolin-1 tubule formation. Both overexpression and inhibition of dynamin-2 reduced the abundance of caveolin-1 tubules. Caveolin-1 reexpression in SK-BR-3 breast cancer cells also induced formation of short membrane tubules close to cortical actin filaments, which required actin filaments but not microtubules. Actomyosin-induced tension destabilized both long and short tubules; they often snapped and resolved to small vesicles. Actin filament depolymerization or myosin II inhibition reduced tension and stabilized tubules. These data demonstrate a new function for PTRF/cavin-1, a new functional interaction between caveolin-1 and Rab8 and that actomyosin interactions can induce tension on caveolin-1-containing membranes.

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