Insulin-like growth factor I (IGF-1) Ec/Mechano Growth factor--a splice variant of IGF-1 within the growth plate.

Human insulin-like growth factor 1 Ec (IGF-1Ec), also called mechano growth factor (MGF), is a splice variant of insulin-like growth factor 1 (IGF-1), which has been shown in vitro as well as in vivo to induce growth and hypertrophy in mechanically stimulated or damaged muscle. Growth, hypertrophy and responses to mechanical stimulation are important reactions of cartilaginous tissues, especially those in growth plates. Therefore, we wanted to ascertain if MGF is expressed in growth plate cartilage and if it influences proliferation of chondrocytes, as it does in musculoskeletal tissues.

Increased RLS prevalence in children and adolescents with migraine: a case-control study.

Background: Previous studies have reported an increased frequency of restless legs syndrome (RLS) in adult migraine patients. Until now, the frequency of RLS in pediatric patients has not been investigated. We set out to assess the frequency of RLS in children and adolescents with migraine compared to headache-free controls.

Splicing transitions of the anchoring protein ENH during striated muscle development.

The ENH (PDLIM5) protein acts as a scaffold to tether various functional proteins at subcellular sites via PDZ and three LIM domains. Splicing of the ENH primary transcript generates various products with different repertories of protein interaction modules. Three LIM-containing ENH predominates in neonatal cardiac tissue, whereas LIM-less ENHs are abundant in adult hearts, as well as skeletal muscles.

Gene expression profiling of rat spermatogonia and Sertoli cells reveals signaling pathways from stem cells to niche and testicular cancer cells to surrounding stroma.

Background: Stem cells and their niches are studied in many systems, but mammalian germ stem cells (GSC) and their niches are still poorly understood. In rat testis, spermatogonia and undifferentiated Sertoli cells proliferate before puberty, but at puberty most spermatogonia enter spermatogenesis, and Sertoli cells differentiate to support this program. Thus, pre-pubertal spermatogonia might possess GSC potential and pre-pubertal Sertoli cells niche functions.

Signal transduction via G protein coupled receptors: a personal outlook.

Intense research continues to address transmembrane signal transduction. Here we recall seven fundamental concepts governing this field. Only signal transduction via G protein coupled receptors (GPCR), is explicitly considered.

Changes in the endogenous BMP expression during redifferentiation of chondrocytes in 3D cultures.

Engineering cartilage tissue is challenging, mainly because chondrocytes lose their differentiated phenotype when cultured in monolayer. The aim of this study was to analyse the influence of 3D-culture conditions on the redifferentiation of chondrocytes, devoting special attention to BMPs. Dedifferentiated chondrocytes were seeded onto two different scaffolds (Bio-Gide and HYAFF-11) and were then cultured for 38 days.

IGF expression patterns and regulation in growth plate chondrocytes.

IGF-I and IGF-II are key regulators of growth and metabolism. Still, data about their expression and distribution within the growth plate in different animal models remain contradictory. Inferences drawn from rodent animal models can only be applied to human conditions to a limited extent as the rodent's growth plate never fuses.

Promoter-proximal pausing of RNA polymerase II: an opportunity to regulate gene transcription.

Transcription of eukaryotic genes by RNA polymerase II (pol II) is a complex, highly regulated multiphasic process. Pol II pauses in the proximity of the promoter on a large fraction of transcribed genes. Transcription initiation and elongation of transcripts are under distinct control.

Splice variants of enigma homolog, differentially expressed during heart development, promote or prevent hypertrophy.

Aims: Proteins with a PDZ (for PSD-95, DLG, ZO-1) and one to three LIM (for Lin11, Isl-1, Mec-3) domains are scaffolding sarcomeric and cytoskeletal elements that form structured muscle fibres and provide for the link to intracellular signalling by selectively associating protein kinases, ion channels, and transcription factors with the mechanical stress-strain sensors. Enigma homolog (ENH) is a PDZ-LIM protein with four splice variants: ENH1 with an N-terminal PDZ domain and three C-terminal LIM domains and ENH2, ENH3, and ENH4 without LIM domains. We addressed the functional role of ENH alternative splicing.

Transcription elongation factors are involved in programming hormone production in pituitary neuroendocrine GH4C1 cells.

Transcription elongation of many eukaryotic genes is regulated. Two negative transcription elongation factors, 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) sensitivity-inducing factor (DSIF) and negative elongation factor (NELF) are known to stall collaboratively RNA polymerase II promoter proximally. We discovered that DSIF and NELF are linked to hormone expression in rat pituitary GH4C1 cells.

The FoxO/Bcl-6/cyclin D2 pathway mediates metabolic and growth factor stimulation of proliferation in Min6 pancreatic beta-cells.

Lack of nutrients and growth factors activates FoxO transcription factors in pancreatic beta-cells, whereas PI3K/Akt-dependent inactivation of FoxO favors proliferation. To address the link between FoxO and cell cycle control, we deprived Min6 cells of serum and glucose which activated FoxO and inhibited proliferation. Concomitantly, expression of the transcriptional repressor Bcl-6 was stimulated, whereas cyclin D2 was lowered.

Dedifferentiation of human articular chondrocytes is associated with alterations in expression patterns of GDF-5 and its receptors.

Human articular chondrocytes are expanded in monolayer culture in order to obtain sufficient cells for matrix-associated cartilage transplantation. During this proliferation process, the cells change their shape as well as their expression profile. These changes resemble those that occur during embryogenesis, when the limb anlagen form the interzone that later develops the joint cleft.

The transcription elongation factors NELF, DSIF and P-TEFb control constitutive transcription in a gene-specific manner.

We examined whether transcription elongation factors control constitutive transcription of the histone H1(0) and GAPDH genes. Chromatin immunoprecipitation demonstrated positive transcription elongation factor b (P-TEFb) and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) sensitivity-inducing factor (DSIF) present together with RNA polymerase II (pol II) throughout the histone H1(0) gene, whereas negative elongation factor (NELF) was confined to the 5' region. Contrarily, DSIF, NELF and pol II were confined to the 5' region on the GAPDH.

Alterations in CD44 isoforms and HAS expression in human articular chondrocytes during the de- and re-differentiation processes.

The purpose of this study was to investigate the expression of different CD44 and hyaluronan synthase isoforms in cartilage, their alterations during the chondrocyte dedifferentiation process in monolayer culture and during the redifferentiation process on 3D scaffolds. Chondrocytes isolated from human articular cartilage were cultured as a monolayer for up to 36 days and were seeded on two different 3D scaffolds (HYAFF 11 and Bio-Gide). Expression levels of CD44s, CD44-lt, CD44-st, HAS1, HAS2, HAS3 and UDPGD were determined by real-time RT-PCR at different time points.

A functional NF-kappaB enhancer element in the first intron contributes to the control of c-fos transcription.

Eukaryotic gene transcription is controlled not only by gene promoters but also by intragenic cis-elements. Such regulation is important for the transcription of immediate early genes (IEGs) and in particular for the c-fos gene, the first intron of which contains many potential transcription factor binding elements. In the present study, we addressed the intronic control of c-fos transcription by the NF-kappaB signalling pathway in the neuroendocrine cell line GH4C1.

Negative elongation factor NELF controls transcription of immediate early genes in a stimulus-specific manner.

The transcription rate of immediate early genes (IEGs) is controlled directly by transcription elongation factors at the transcription elongation step. Negative elongation factor (NELF) and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) sensitivity-inducing factor (DSIF) stall RNA polymerase II (pol II) soon after transcription initiation. Upon induction of IEG transcription, DSIF is converted into an accelerator for pol II elongation.

Scaffold-dependent differentiation of human articular chondrocytes.

Matrix-associated autologous chondrocyte transplantation (MACT) is a tissue-engineered approach for the treatment of cartilage defects and combines autologous chondrocytes seeded on biomaterials. The objective of the study is the analysis of growth and differentiation behaviour of human articular chondrocytes grown on three different matrices used for MACT. Human articular chondrocytes were kept in monolayer culture for 42 days and then seeded on matrices consisting of either collagen type I/III, hyaluronan, or gelatine.

FoxO proteins in pancreatic β-cells as potential therapeutic targets in diabetes.

Diabetes results from complete (Type 1) or progressive (Type 2) insulin insufficiency. Resulting chronic and acute hyperglycemia are thus prevented mainly by insulin injections, a therapy that is care intensive, costly and does not abolish vascular damage, with severe consequences for the patient in the long term. In view of the epidemic spread of the disease, diabetes is considered a major threat for public healthcare systems.

Enigma homolog 1 scaffolds protein kinase D1 to regulate the activity of the cardiac L-type voltage-gated calcium channel.

Aims: In cardiomyocytes, protein kinase D1 (PKD1) plays a central role in the response to stress signals. From a yeast two-hybrid assay, we have identified Enigma Homolog 1 (ENH1) as a new binding partner of PKD1. Since in neurons, ENH1, associated with protein kinase Cepsilon, was shown to modulate the activity of N-type calcium channels, and the pore-forming subunit of the cardiac L-type voltage-gated calcium channel, alpha1C, possesses a potential phosphorylation site for PKD1, we studied here a possible role of ENH1 and PKD1 in the regulation of the cardiac L-type voltage-gated calcium channel.

Up-regulation of P-TEFb by the MEK1-extracellular signal-regulated kinase signaling pathway contributes to stimulated transcription elongation of immediate early genes in neuroendocrine cells.

The positive elongation factor P-TEFb appears to function as a crucial C-terminal-domain (CTD) kinase for RNA polymerase II (Pol II) transcribing immediate early genes (IEGs) in neuroendocrine GH4C1 cells. Chromatin immunoprecipitation indicated that in resting cells Pol II occupied the promoter-proximal regions of the c-fos and junB genes, together with the negative elongation factors DSIF and NELF. Thyrotropin-releasing hormone (TRH)-induced recruitment of positive transcription elongation factor b (P-TEFb) abolished the pausing of Pol II and enhanced phosphorylation of CTD serine 2, resulting in transcription elongation.

NOX5 is expressed at the plasma membrane and generates superoxide in response to protein kinase C activation.

NOX5 is a ROS-generating NADPH oxidase which contains an N-terminal EF-hand region and can be activated by cytosolic Ca(2+) elevations. However the C-terminal region of NOX5 also contains putative phosphorylation sites. In this study we used HEK cells stably expressing NOX5 to analyze the size and subcellular localization of the NOX5 protein, its mechanisms of activation, and the characteristics of the ROS released.

Transcriptional response of pancreatic beta cells to metabolic stimulation: large scale identification of immediate-early and secondary response genes.

Background: Physiological long term adaptation of pancreatic beta cells is driven by stimuli such as glucose and incretin hormones acting via cAMP (e.g. GLP-1) and involves regulated gene expression.

Sequential actions of ERK1/2 on the AP-1 transcription factor allow temporal integration of metabolic signals in pancreatic beta cells.

The AP-1 transcription factor composed of fos and jun gene products mediates transcriptional responses to hormonal and metabolic stimulations of pancreatic beta cells. Here, we investigated the mechanisms that dynamically control expression of AP-1 subunit proteins. In MIN6 cells, glucose and GLP-1 raised c-FOS protein with biphasic kinetics, an initial peak being followed by a plateau that persisted as long as stimuli were maintained.

NOX4 activity is determined by mRNA levels and reveals a unique pattern of ROS generation.

NOX4 is an enigmatic member of the NOX (NADPH oxidase) family of ROS (reactive oxygen species)-generating NADPH oxidases. NOX4 has a wide tissue distribution, but the physiological function and activation mechanisms are largely unknown, and its pharmacology is poorly understood. We have generated cell lines expressing NOX4 upon tetracycline induction.

The emerging role of FOXO transcription factors in pancreatic beta cells.

FOXO transcription factors critically control fundamental cellular processes, including metabolism, cell differentiation, cell cycle arrest, DNA repair, and other reactions to cellular stress. FOXO factors sense the balance between stimuli promoting growth and differentiation versus stress stimuli signaling damage. Integrated through the FOXO system, these divergent stimuli decide on cell fate, a choice between proliferation, differentiation, or apoptosis.