Loss of oxidative defense and potential blockade of satellite cell maturation in the skeletal muscle of patients with cancer but not in the healthy elderly

Purpose: Muscle wasting in old age or cancer may result from failure of myofibre regeneration and /or accelerated apoptosis both of which may be up-regulated by oxidative stress or inflammation. The aim of this study was to determine from the transcriptome in human skeletal muscle whether there is evidence for oxidative stress and its relationship with satellite cell differentiation or apoptosis in the muscle of patients with cancer (weight-stable: CWS or weight-losing: CWL) or healthy elderly (HE) when compared with healthy middle aged controls (HMAC) . Design: 28 patients with resectable upper GI/pancreatic cancer (CWS: 14 and CWL14), 17 HE and 22 HMAC underwent biopsy of the quadriceps muscle. Markers of muscle regeneration, inflammation, oxidative stress and apoptosis were measured by qPCR. Results: The expression of transcription factors responsible for muscle regeneration (Pax3, Pax7 and MyoD) were increased in the skeletal muscle of CWS and HE when compared with HMAC (P<0.001). In contrast, the expression of myogenic differentiation markers (MyoG and Myh2) was reduced in CWS and CWL but increased in HE when compared with HMAC (P<0.0001). The expression of the pro-apoptotic gene Bax was significantly increased in CWS, CWL and HE compared with HMAC (P<0.0001). Pro-inflammatory cytokine expression was variable with increased expression of TNF in CWS and HE, increased Il-6 in CWS and increased Il-1 in CWL when compared with HMAC. Expression of the oxidative defense genes SOD2, GCLM, and NRF2 was decreased in CWS and CWL but increased in HE when compared with HMA (P<0.0001). Conclusion: There is evidence for blockade of satellite cell maturation, upregulation of apoptosis and reduced oxidative defense in the skeletal muscle of cancer patients. In contrast, in muscle from healthy elderly the potential for myotube differentiation and oxidative defense is maintained

Responses of orchids to habitat change in Corsica over 27 years

International audienc

Temporal dynamics of orchids in a 27-year long interval in Corsica, a study based on a Bayesian multispecies site occupancy model

13-19 aprilInternational audienc

Multi-photon excitation of intrinsic protein fluorescence and its application to pharmaceutical drug screening.

The majority of proteins contain intrinsic fluorophores as natural sensors of molecular structures, dynamics, and interactions. The intrinsic protein fluorescence signal allows for the label-free and, hence, undisturbed and rapid study of protein-ligand interactions. Ultraviolet-based drug screening is hampered by the background, photobleaching, light scattering, inner filter effects, and interfering assay compounds. Such problems can be overcome by means of molecular three-photon excitation (3PE) with infrared femtosecond light pulses since longer excitation wavelengths result in less Raleigh scattering, and the subfemtoliter (confocal-like) 3PE volume minimizes out-of-focus photobleaching, background generation, and inner filter effects. We demonstrate the general feasibility of 3PE for protein spectroscopy and illustrate the technique's excellent potential for high-throughput screening. By using the intrinsic fluorescence intensity of a protein-substrate, we were able to discriminate between ligands of different affinities in binding assays

Evidence for ligand-independent transcriptional activation of the human estrogen-related receptor alpha (ERRalpha): crystal structure of ERRalpha ligand binding domain in complex with peroxisome proliferator-activated receptor coactivator-1alpha.

The crystal structure of the ligand binding domain (LBD) of the estrogen-related receptor alpha (ERRalpha, NR3B1) complexed with a coactivator peptide from peroxisome proliferator-activated receptor coactivator-1alpha (PGC-1alpha) reveals a transcriptionally active conformation in the absence of a ligand. This is the first x-ray structure of ERRalpha LBD, solved to a resolution of 2.5 A, and the first structure of a PGC-1alpha complex. The putative ligand binding pocket (LBP) of ERRalpha is almost completely occupied by side chains, in particular with the bulky side chain of Phe328 (corresponding to Ala272 in ERRgamma and Ala350 in estrogen receptor alpha). Therefore, a ligand of a size equivalent to more than approximately 4 carbon atoms could only bind in the LBP, if ERRalpha would undergo a major conformational change (in particular the ligand would displace H12 from its agonist position). The x-ray structure thus provides strong evidence for ligand-independent transcriptional activation by ERRalpha. The interactions of PGC-1alpha with ERRalpha also reveal for the first time the atomic details of how a coactivator peptide containing an inverted LXXLL motif (namely a LLXYL motif) binds to a LBD. In addition, we show that a PGC-1alpha peptide containing this nuclear box motif from the L3 site binds ERRalpha LBD with a higher affinity than a peptide containing a steroid receptor coactivator-1 motif and that the affinity is further enhanced when all three leucine-rich regions of PGC-1alpha are present

Autocrine activin A signaling in cancer cells controls secretion of IL-6 and autophagy in cancer cachexia

Background - The majority of patients with advanced cancer develop cachexia, a weight loss syndrome that severely reduces quality of life and limits survival. Our understanding of the underlying mechanisms that cause the condition is limited, and there are currently no treatment options that can completely reverse cachexia. Several tumor-derived factors and inflammatory mediators have been suggested to contribute to weight loss in cachectic patients. However, inconsistencies between studies are recurrent. Activin A and IL-6 are among the best studied factors that seem to be important, and several studies support their individual role in cachexia development. Methods – We investigated the interplay between activin A and IL-6 in the cachexia inducing TOV21G cell line both in culture and in tumours in mice. We previously found that the human TOV21G cells secrete IL-6 that induce autophagy in reporter cells and cachexia in mice. Using this established cachexia cell model, we targeted autocrine Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation activin A by genetic, chemical and biological approaches. The secretion of IL-6 from the cancer cells was determined both in culture and tumor-bearing mice by a species specific ELISA. Autophagy reporter cells were used to monitor the culture medium for autophagy inducing activities and muscle mass changes were evaluated in tumor bearing mice. Results – We show that activin A acts in an autocrine manner to promote the synthesis and secretion of IL-6 from cancer cells. We find that this is important for the ability of the cancer cells to accelerate autophagy in non-cancerous cells. Consistently, interfering with activin A signaling in cachectic tumor-bearing mice reduces serum levels of cancer cell-derived IL-6 and reverses cachexia. Thus, our data support a functional link between activin and IL-6 signaling pathways, and indicate that interference with activin A-induced IL-6 secretion from the tumor has therapeutic potential for cancer-induced cachexia

Loss of oxidative defense and potential blockade of satellite cell maturation in the skeletal muscle of patients with cancer but not healthy elderly

Purpose: Muscle wasting in old age or cancer may result from failure of myofibre regeneration and /or accelerated apoptosis both of which may be up-regulated by oxidative stress or inflammation. The aim of this study was to determine from the transcriptome in human skeletal muscle whether there is evidence for oxidative stress and its relationship with satellite cell differentiation or apoptosis in the muscle of patients with cancer (weight-stable: CWS or weight-losing: CWL) or healthy elderly (HE) when compared with healthy middle aged controls (HMAC) . Design: 28 patients with resectable upper GI/pancreatic cancer (CWS: 14 and CWL14), 17 HE and 22 HMAC underwent biopsy of the quadriceps muscle. Markers of muscle regeneration, inflammation, oxidative stress and apoptosis were measured by qPCR. Results: The expression of transcription factors responsible for muscle regeneration (Pax3, Pax7 and MyoD) were increased in the skeletal muscle of CWS and HE when compared with HMAC (P<0.001). In contrast, the expression of myogenic differentiation markers (MyoG and Myh2) was reduced in CWS and CWL but increased in HE when compared with HMAC (P<0.0001). The expression of the pro-apoptotic gene Bax was significantly increased in CWS, CWL and HE compared with HMAC (P<0.0001). Pro-inflammatory cytokine expression was variable with increased expression of TNF in CWS and HE, increased Il-6 in CWS and increased Il-1 in CWL when compared with HMAC. Expression of the oxidative defense genes SOD2, GCLM, and NRF2 was decreased in CWS and CWL but increased in HE when compared with HMA (P<0.0001). Conclusion: There is evidence for blockade of satellite cell maturation, upregulation of apoptosis and reduced oxidative defense in the skeletal muscle of cancer patients. In contrast, in muscle from healthy elderly the potential for myotube differentiation and oxidative defense is maintained

Synthesis and characterization of fluorescent ubiquitin derivatives as highly sensitive substrates for the deubiquitinating enzymes UCH-L3 and USP-2.

Deubiquitinating enzymes (DUBs) catalyze the removal of attached ubiquitin molecules from amino groups of target proteins. The large family of DUBs plays an important role in the regulation of the intracellular homeostasis of different proteins and influences therefore key events such as cell division, apoptosis, etc. The DUB family members UCH-L3 and USP2 are believed to inhibit the degradation of various tumor-growth-promoting proteins by removing the trigger for degradation. Inhibitors of these enzymes should therefore lead to enhanced degradation of oncoproteins and may thus stop tumor growth. To develop an enzymatic assay for the search of UCH-L3 and USP2 inhibitors, C-terminally labeled ubiquitin substrates were enzymatically synthesized. We have used the ubiquitin-activating enzyme E1 and one of the ubiquitin-conjugating enzymes E2 to attach a fluorescent lysine derivative to the C terminus of ubiquitin. Since only the epsilon-NH(2) group of the lysine derivatives was free and reactive, the conjugates closely mimic the isopeptide bond between the ubiquitin and the lysine side chains of the targeted proteins. Various substrates were synthesized by this approach and characterized enzymatically with the two DUBs. The variant consisting of the fusion protein between the large N-terminal NusA tag and the ubiquitin which was modified with alpha-NH(2)-tetramethylrhodamin-lysine, was found to give the highest dynamic range in a fluorescence polarization readout. Therefore we have chosen this substrate for the development of a miniaturized, fluorescence-polarization-based high-throughput screening assay