Release of eIF6 (p27BBP) from the 60S subunit allows 80S ribosome assembly

The assembly of 80S ribosomes requires joining of the 40S and 60S subunits, which is triggered by the formation of an initiation complex on the 40S subunit. This event is rate-limiting for translation, and depends on external stimuli and the status of the cell. Here we show that 60S subunits are activated by release of eIF6 (also termed p27BBP). In the cytoplasm, eIF6 is bound to free 60S but not to 80S. Furthermore, eIF6 interacts in the cytoplasm with RACK1, a receptor for activated protein kinase C (PKC). RACK1 is a major component of translating ribosomes, which harbour significant amounts of PKC. Loading 60S subunits with eIF6 caused a dose-dependent translational block and impairment of 80S formation, which were reversed by expression of RACK1 and stimulation of PKC in vivo and in vitro. PKC stimulation led to eIF6 phosphorylation, and mutation of a serine residue in the carboxy terminus of eIF6 impaired RACK1/PKC-mediated translational rescue. We propose that eIF6 release regulates subunit joining, and that RACK1 provides a physical and functional link between PKC signalling and ribosome activation.

MTORC1 regulates cardiac function and myocyte survival through 4E-BP1 inhibition in mice

Mechanistic target of rapamycin (MTOR) plays a critical role in the regulation of cell growth and in the response to energy state changes. Drugs inhibiting MTOR are increasingly used in antineoplastic therapies. Myocardial MTOR activity changes during hypertrophy and heart failure (HF). However, whether MTOR exerts a positive or a negative effect on myocardial function remains to be fully elucidated. Here, we show that ablation of Mtor in the adult mouse myocardium results in a fatal, dilated cardiomyopathy that is characterized by apoptosis, autophagy, altered mitochondrial structure, and accumulation of eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). 4E-BP1 is an MTOR-containing multiprotein complex-1 (MTORC1) substrate that inhibits translation initiation. When subjected to pressure overload, Mtor-ablated mice demonstrated an impaired hypertrophic response and accelerated HF progression. When the gene encoding 4E-BP1 was ablated together with Mtor, marked improvements were observed in apoptosis, heart function, and survival. Our results demonstrate a role for the MTORC1 signaling network in the myocardial response to stress. In particular, they highlight the role of 4E-BP1 in regulating cardiomyocyte viability and in HF. Because the effects of reduced MTOR activity were mediated through increased 4E-BP1 inhibitory activity, blunting this mechanism may represent a novel therapeutic strategy for improving cardiac function in clinical HF.

Activation or inactivation of cardiac Akt/mTOR signaling diverges physiological from pathological hypertrophy

Cardiomyocyte hypertrophy differs according to the stress exerted on the myocardium. While pressure overload-induced cardiomyocyte hypertrophy is associated with depressed contractile function, physiological hypertrophy after exercise training associates with preserved or increased inotropy. We determined the activation state of myocardial Akt signaling with downstream substrates and fetal gene reactivation in exercise-induced physiological and pressure overload-induced pathological hypertrophies. C57BL/6J mice were either treadmill trained for 6 weeks, 5 days/week, at 85-90% of maximal oxygen uptake (VO(2max)), or underwent transverse aortic constriction (TAC) for 1 or 8 weeks. Total and phosphorylated protein levels were determined with SDS-PAGE, and fetal genes by real-time RT-PCR. In the physiologically hypertrophied heart after exercise training, total Akt protein level was unchanged, but Akt was chronically hyperphosphorylated at serine 473. This was accompanied by activation of the mammalian target of rapamycin (mTOR), measured as phosphorylation of its two substrates: the ribosomal protein S6 kinase-1 (S6K1) and the eukaryotic translation initiation factor-4E binding protein-1 (4E-BP1). Exercise training did not reactivate the fetal gene program (beta-myosin heavy chain, atrial natriuretic factor, skeletal muscle actin). In contrast, pressure overload after TAC reactivated fetal genes already after 1 week, and partially inactivated the Akt/mTOR pathway and downstream substrates after 8 weeks. In conclusion, changes in opposite directions of the myocardial Akt/mTOR signal pathway appears to distinguish between physiological and pathological hypertrophies; exercise training associating with activation and pressure overload associating with inactivation of the Akt/mTOR pathway.

Interval training normalizes cardiomyocyte function, diastolic Ca2+ control, and SR Ca2+ release synchronicity in a mouse model of diabetic cardiomyopathy

RATIONALE

In the present study we explored the mechanisms behind excitation-contraction (EC) coupling defects in cardiomyocytes from mice with type-2 diabetes (db/db).

OBJECTIVE

We determined whether 13 weeks of aerobic interval training could restore cardiomyocyte Ca(2+) cycling and EC coupling.

METHODS AND RESULTS

Reduced contractility in cardiomyocytes isolated from sedentary db/db was associated with increased diastolic sarcoplasmic reticulum (SR)-Ca(2+) leak, reduced synchrony of Ca(2+) release, reduced transverse (T)-tubule density, and lower peak systolic and diastolic Ca(2+) and caffeine-induced Ca(2+) release. Additionally, the rate of SR Ca(2+) ATPase-mediated Ca(2+) uptake during diastole was reduced, whereas a faster recovery from caffeine-induced Ca(2+) release indicated increased Na(+)/Ca(2+)-exchanger activity. The increased SR-Ca(2+) leak was attributed to increased Ca(2+)-calmodulin-dependent protein kinase (CaMKIIdelta) phosphorylation, supported by the normalization of SR-Ca(2+) leak on inhibition of CaMKIIdelta (AIP). Exercise training restored contractile function associated with restored SR Ca(2+) release synchronicity, T-tubule density, twitch Ca(2+) amplitude, SR Ca(2+) ATPase and Na(+)/Ca(2+)-exchanger activities, and SR-Ca(2+) leak. The latter was associated with reduced phosphorylation of cytosolic CaMKIIdelta. Despite normal contractile function and Ca(2+) handling after the training period, phospholamban was hyperphosphorylated at Serine-16. Protein kinase A inhibition (H-89) in cardiomyocytes from the exercised db/db group abolished the differences in SR-Ca(2+) load when compared with the sedentary db/db mice. EC coupling changes were observed without changes in serum insulin or glucose levels, suggesting that the exercise training-induced effects are not via normalization of the diabetic condition.

CONCLUSIONS

These data demonstrate that aerobic interval training almost completely restored the contractile function of the diabetic cardiomyocyte to levels close to sedentary wild type.

Aerobic interval training enhances cardiomyocyte contractility and Ca2+ cycling by phosphorylation of CaMKII and Thr-17 of phospholamban

Cardiac adaptation to aerobic exercise training includes improved cardiomyocyte contractility and calcium handling. Our objective was to determine whether cytosolic calcium/calmodulin-dependent kinase II and its downstream targets are modulated by exercise training. A six-week aerobic interval training program by treadmill running increased maximal oxygen uptake by 35% in adult mice, whereupon left ventricular cardiomyocyte function was studied and myocardial tissue samples were used for biochemical analysis. Cardiomyocytes from trained mice had enhanced contractility and faster relaxation rates, which coincided with larger amplitude and faster decay of the calcium transient, but not increased peak systolic calcium levels. These changes were associated with reduced phospholamban expression relative to sarcoplasmic reticulum calcium ATPase and constitutively increased phosphorylation of phospholamban at the threonine 17, but not at the serine 16 site. Calcium/calmodulin-dependent kinase IIdelta phosphorylation was increased at threonine 287, indicating activation. To investigate the physiological role of calcium/calmodulin-dependent kinase IIdelta phosphorylation, this kinase was blocked specifically by autocamtide-2 related inhibitory peptide II. This maneuver completely abolished training-induced improvements of cardiomyocyte contractility and calcium handling and blunted, but did not completely abolish the training-induced increase in Ca(2+) sensitivity. Also, inhibition of calcium/calmodulin-dependent kinase II reduced the greater frequency-dependent acceleration of relaxation that was observed after aerobic interval training. These observations indicate that calcium/calmodulin-dependent kinase IIdelta contributes significantly to the functional adaptation of the cardiomyocyte to regular exercise training.

Taking pain out of NGF: a "painless" NGF mutant, linked to hereditary sensory autonomic neuropathy type V, with full neurotrophic activity

During adulthood, the neurotrophin Nerve Growth Factor (NGF) sensitizes nociceptors, thereby increasing the response to noxious stimuli. The relationship between NGF and pain is supported by genetic evidence: mutations in the NGF TrkA receptor in patients affected by an hereditary rare disease (Hereditary Sensory and Autonomic Neuropathy type IV, HSAN IV) determine a congenital form of severe pain insensitivity, with mental retardation, while a mutation in NGFB gene, leading to the aminoacid substitution R100W in mature NGF, determines a similar loss of pain perception, without overt cognitive neurological defects (HSAN V). The R100W mutation provokes a reduced processing of proNGF to mature NGF in cultured cells and a higher percentage of neurotrophin secreted is in the proNGF form. Moreover, using Surface Plasmon Resonance we showed that the R100W mutation does not affect NGF binding to TrkA, while it abolishes NGF binding to p75NTR receptors. However, it remains to be clarified whether the major impact of the mutation is on the biological function of proNGF or of mature NGF and to what extent the effects of the R100W mutation on the HSAN V clinical phenotype are developmental, or whether they reflect an impaired effectiveness of NGF to regulate and mediate nociceptive transmission in adult sensory neurons. Here we show that the R100 mutation selectively alters some of the signaling pathways activated downstream of TrkA NGF receptors. NGFR100 mutants maintain identical neurotrophic and neuroprotective properties in a variety of cell assays, while displaying a significantly reduced pain-inducing activity in vivo (n = 8-10 mice/group). We also show that proNGF has a significantly reduced nociceptive activity, with respect to NGF. Both sets of results jointly contribute to elucidating the mechanisms underlying the clinical HSAN V manifestations, and to clarifying which receptors and intracellular signaling cascades participate in the pain sensitizing action of NGF.

Increased cytoplasmic TDP-43 reduces global protein synthesis by interacting with RACK1 on polyribosomes

TDP-43 is a well known RNA binding protein involved in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Lobar Dementia (FTLD). In physiological conditions, TDP-43 mainly localizes in the nucleus and shuttles, at least in neurons, to the cytoplasm to form TDP-43 RNA granules. In the nucleus, TDP-43 participates to the expression and splicing of RNAs, while in the cytoplasm its functions range from transport to translation of specific mRNAs. However, if loss or gain of these TDP-43 functions are affected in ALS/FTLD pathogenesis is not clear. Here, we report that TDP-43 localizes on ribosomes not only in primary neurons but also in SH-SY5Y human neuroblastoma cells. We find that binding of TDP-43 to the translational machinery is mediated by an interaction with a specific ribosomal protein, RACK1, and that an increase in cytoplasmic TDP-43 represses global protein synthesis, an effect which is rescued by overexpression of RACK1. Ribosomal loss of RACK1, which excludes TDP-43 from the translational machinery, remarkably reduces formation of TDP-43 cytoplasmic inclusions in neuroblastoma cells. Finally, we corroborate the interaction between TDP-43 and RACK1 on polyribosomes of neuroblastoma cells with mis-localization of RACK1 on TDP-43 positive cytoplasmic inclusions in motor neurons of ALS patients. In conclusions, results from this study suggest that TDP-43 represents a translational repressor not only for specific mRNAs but for overall translation and that its binding to polyribosomes through RACK1 may promote, under conditions inducing ALS pathogenesis, the formation of cytoplasmic inclusions.

Environmental pollution and toxic substances: Cellular apoptosis as a key parameter in a sensible model like fish

The industrial wastes, sewage effluents, agricultural run-off and decomposition of biological waste may cause high environmental concentration of chemicals that can interfere with the cell cycle activating the programmed process of cells death (apoptosis). In order to provide a detailed understanding of environmental pollutants-induced apoptosis, here we reviewed the current knowledge on the interactions of environmental chemicals and programmed cell death. Metals (aluminum, arsenic, cadmium, chromium, cobalt, zinc, copper, mercury and silver) as well as other chemicals including bleached kraft pulp mill effluent (BKME), persistent organic pollutants (POPs), and pesticides (organo-phosphated, organo-chlorinated, carbamates, phyretroids and biopesticides) were evaluated in relation to apoptotic pathways, heat shock proteins and metallothioneins. Although research performed over the past decades has improved our understanding of processes involved in apoptosis in fish, yet there is lack of knowledge on associations between environmental pollutants and apoptosis. Thus, this review could be useful tool to study the cytotoxic/apoptotic effects of different pollutants in fish species.

A novel, blocking, Fc-silent anti-CD40 monoclonal antibody prolongs nonhuman primate renal allograft survival in the absence of B cell depletion

CD40-CD154 pathway blockade prolongs renal allograft survival in nonhuman primates (NHPs). However, antibodies targeting CD154 were associated with an increased incidence of thromboembolic complications. Antibodies targeting CD40 prolong renal allograft survival in NHPs without thromboembolic events but with accompanying B cell depletion, raising the question of the relative contribution of B cell depletion to the efficacy of anti-CD40 blockade. Here, we investigated whether fully silencing Fc effector functions of an anti-CD40 antibody can still promote graft survival. The parent anti-CD40 monoclonal antibody HCD122 prolonged allograft survival in MHC-mismatched cynomolgus monkey renal allograft transplantation (52, 22, and 24 days) with accompanying B cell depletion. Fc-silencing yielded CFZ533, an antibody incapable of B cell depletion but still able to potently inhibit CD40 pathway activation. CFZ533 prolonged allograft survival and function up to a defined protocol endpoint of 98-100 days (100, 100, 100, 98, and 76 days) in the absence of B cell depletion and preservation of good histological graft morphology. CFZ533 was well-tolerated, with no evidence of thromboembolic events or CD40 pathway activation and suppressed a gene signature associated with acute rejection. Thus, use of the Fc-silent anti-CD40 antibody CFZ533 appears to be an attractive approach for preventing solid organ transplant rejection.

Akt increases sarcoplasmic reticulum Ca2+ cycling by direct phosphorylation of phospholamban at Thr17

Cardiomyocytes adapt to physical stress by increasing their size while maintaining cell function. The serine/threonine kinase Akt plays a critical role in this process of adaptation. We previously reported that transgenic overexpression of an active form of Akt (Akt-E40K) in mice results in increased cardiac contractility and cell size, as well as improved sarcoplasmic reticulum (SR) Ca(2+) handling. Because it is not fully elucidated, we decided to study the molecular mechanism by which Akt-E40K overexpression improves SR Ca(2+) handling. To this end, SR Ca(2+) uptake and the phosphorylation status of phospholamban (PLN) were evaluated in heart extracts from wild-type and Akt-E40K mice and mice harboring inducible and cardiac specific knock-out of phosphatidylinositol-dependent kinase-1, the upstream activator of Akt. Moreover, the effect of Akt was assessed in vitro by overexpressing a mutant Akt targeted preferentially to the SR, and by biochemical assays to evaluate potential interaction with PLN. We found that when activated, Akt interacts with and phosphorylates PLN at Thr(17), the Ca(2+)-calmodulin-dependent kinase IIdelta site, whereas silencing Akt signaling, through the knock-out of phosphatidylinositol-dependent kinase-1, resulted in reduced phosphorylation of PLN at Thr(17). Furthermore, overexpression of SR-targeted Akt in cardiomyocytes improved Ca(2+) handling without affecting cell size. Thus, we describe here a new mechanism whereby the preferential translocation of Akt to the SR is responsible for enhancement of contractility without stimulation of hypertrophy.

Intranasal "painless" human Nerve Growth Factor [corrected] slows amyloid neurodegeneration and prevents memory deficits in App X PS1 mice

Nerve Growth Factor (NGF) is being considered as a therapeutic candidate for Alzheimer's disease (AD) treatment but the clinical application is hindered by its potent pro-nociceptive activity. Thus, to reduce systemic exposure that would induce pain, in recent clinical studies NGF was administered through an invasive intracerebral gene-therapy approach. Our group demonstrated the feasibility of a non-invasive intranasal delivery of NGF in a mouse model of neurodegeneration. NGF therapeutic window could be further increased if its nociceptive effects could be avoided altogether. In this study we exploit forms of NGF, mutated at residue R100, inspired by the human genetic disease HSAN V (Hereditary Sensory Autonomic Neuropathy Type V), which would allow increasing the dose of NGF without triggering pain. We show that "painless" hNGF displays full neurotrophic and anti-amyloidogenic activities in neuronal cultures, and a reduced nociceptive activity in vivo. When administered intranasally to APPxPS1 mice ( n = 8), hNGFP61S/R100E prevents the progress of neurodegeneration and of behavioral deficits. These results demonstrate the in vivo neuroprotective and anti-amyloidogenic properties of hNGFR100 mutants and provide a rational basis for the development of "painless" hNGF variants as a new generation of therapeutics for neurodegenerative diseases.

RACK1 is a ribosome scaffold protein for β-actin mRNA/ZBP1 complex

In neurons, specific mRNAs are transported in a translationally repressed manner along dendrites or axons by transport ribonucleic-protein complexes called RNA granules. ZBP1 is one RNA binding protein present in transport RNPs, where it transports and represses the translation of cotransported mRNAs, including β-actin mRNA. The release of β-actin mRNA from ZBP1 and its subsequent translation depends on the phosphorylation of ZBP1 by Src kinase, but little is known about how this process is regulated. Here we demonstrate that the ribosomal-associated protein RACK1, another substrate of Src, binds the β-actin mRNA/ZBP1 complex on ribosomes and contributes to the release of β-actin mRNA from ZBP1 and to its translation. We identify the Src binding and phosphorylation site Y246 on RACK1 as the critical site for the binding to the β-actin mRNA/ZBP1 complex. Based on these results we propose RACK1 as a ribosomal scaffold protein for specific mRNA-RBP complexes to tightly regulate the translation of specific mRNAs.

Molecular determinants of the physiological adaptation to stress in the cardiomyocyte: a focus on AKT

Cardiomyocytes (CMCs) adapt to physiological or pathological stimuli by undergoing molecular changes which differentiate according to the specificity of the stimulus and eventually generate a phenotype with peculiar molecular characteristics. Here, we review the literature on the molecular mechanisms activated in the CMC during physiologic adaptation to stress, as opposed to maladaptation. The critical role of the IGF-1 receptor/PI3K/Akt signaling pathway during this process is described, including effector targets regulating inotropism and cell size.

Prevalence of pain in elderly hospitalized patients

Several studies indicate that pain, although very common in the elderly, is under-treated, because it is considered as a concomitant effect of aging. This study aimed to evaluate the prevalence of pain among patients in eight Italian geriatric hospital departments, correlated to prescribed therapy. We enrolled 387 patients in the study, 367 of whom were evaluated. Each patient's recovery, co-morbidity, pain intensity, prescribed therapy, side effects, duration of pain, and efficacy of therapy were monitored during two 15-day periods from 15 July to end of August 2008, and from 1 October to 15 November 2008. The results of this study confirmed that hypertension, cardiopathic disease, diabetes, and chronic obstructive pulmonary disease (COPD) are common pathologies, and that pain is present in 67.3% of those recovered in geriatric departments. In general, however, pain is not treated. Indeed only 49% of those with pain had any type of treatment, which was adequate for the pain intensity. In fact 74.5% of patients considered the therapy to be of low or no efficacy. These data demonstrate the presence of pain in a high percentage of elderly patients, which is either not treated, or treated inadequately. Controlling pain is essential in elderly patients in order to allow a normal life and an active role in family and society. The main conclusion is that pain is often poorly considered in the elderly, thus leading to a dangerous under-treatment. We want to underline the crucial clinical impact of such under-treatment in elderly patients.

High-level resistance to gentamicin: genetic transfer between Enterococcus faecalis isolated from food of animal origin and human microbiota

AIMS

  To investigate the in vivo gene transfer of high-level gentamicin resistance (HLRG) from Enterococcus faecalis isolated from the food of animal origin to a human isolate, using a mouse model of intestinally colonized human microbiota.

METHODS AND RESULTS

  In vitro study: The presence of plasmids involved in HLRG coding was investigated. After the conjugation experiment, the recipient strain, Ent. faecalis JH2-SS, acquired a plasmid responsible for HLRG [minimal inhibitory concentration (MIC) >800 μg ml(-1) ], in a similar position to the donor cells. In vivo study: Seven BALB/c mice were dosed with ceftriaxone (400 mg kg(-1) ) and then inoculated with a dilution of 1/100 of human faeces (HFc). After 72 h, Ent. faecalis JH2-SS (recipient) was inoculated and then, after a further 72 h, the animals were given Ent. faecalis CS19, isolated from the food of animal origin, involved in HLRG (donor). The presence of transconjugant strains in HFc was subsequently recorded on a daily basis until the end of the experiment. The clonal relationship between Ent. faecalis and Escherichia coli in faeces was assessed by RAPD-PCR. Both the in vitro and in vivo studies showed that the receptor strain acquired a plasmid responsible for HLRG (MICs >800 μg ml(-1) ), which migrated with a similar relative mobility value. Transconjugant strains were detected from 24 h after the donor strain inoculation and persisted until the end of the experiment.

CONCLUSIONS

  The in vivo gene transfer of HLRG from Ent. faecalis strains, isolated from the food of animal origin, to human microbiota has been demonstrated in a mouse model.

SIGNIFICANCE AND IMPACT OF THE STUDY

  The complexity found on the therapeutic responses of invasive infectious diseases caused by Ent. faecalis facilitates the assessment of food of animal origin as a resistant pathogen reservoir. In addition, this study may contribute to the understanding of antimicrobials' resistance gene transfer between Ent. faecalis strains from food and human GI tract.

Diabetes mellitus: lessons from patient education

The education of diabetic patients, proposed as an essential therapeutic tool since the early 1920s and accepted as such by official medicine only in the 1970s, has generated great enthusiasm over the last decade, with increasing concern for greater effectiveness by improved motivation of both patients and doctors. Structured education depends on the precise definition of agreed, short-term objectives, whose attainment shall be verified. Educational objectives may be set at different levels: knowledge of the disease, skills required for treatment, capacity to integrate therapy in everyday life,... The most relevant objectives however are the therapeutic goals of each individual patient, i.e. most often, prevention of acute complications, near-normoglycemia to prevent late complications and foot care to prevent disabling consequences of the latter. This can only be attained through a global approach to the patient, at once medical, educational and psychological. Medical science has definitively confirmed the importance of near- normoglycemia and proposes more effective insulin regimens and new recommendations for diet and exercise. Education demands a lot from health care providers: specific training, teaching skills, good communication, supportive attitude, readiness to listen and to negotiate. Patients' motivation to learn and adhere to treatment is also greatly influenced by individual factors, both psychological and environmental, that need to be taken into account.

Carbon monoxide levels experienced by heavy smokers impair aerobic capacity and cardiac contractility and induce pathological hypertrophy

Cigarette smoke contains hundreds of potentially toxic compounds and is an important risk factor for cardiovascular disease. However, the key components responsible for endothelial and myocardial dysfunction have not been fully identified. The objective of the present study was to determine the cardiovascular effects of long-term inhalation of carbon monoxide (CO) administrated to give concentrations in the blood similar to those observed in heavy smokers. Female rats were exposed to either CO or air (control group) (n = 12). The CO group was exposed to 200 ppm CO (100 h/wk) for 18 mo. Rats exposed to CO had 24% lower maximal oxygen uptake, longer (145 vs. 123 microm) and wider (47 vs. 25 microm) cardiomyocytes, reduced cardiomyocyte fractional shortening (12 vs. 7%), and 26% longer time to 50% re-lengthening than controls. In addition, cardiomyocytes from CO-exposed rats had 48% lower intracellular calcium (Ca2 +) amplitude, 22% longer time to Ca2 + decay, 34% lower capacity of sarcoplasmic reticulum Ca2 +-ATPase (SERCA2a), and 37% less t-tubule area compared to controls. Phosphorylation levels of phospholamban at Ser16 and Thr17 were significantly reduced in the CO group, whereas total concentration of phospholamban and SERCA2a were unchanged. Cardiac atrial natriuretic peptide, vascular endothelial growth factor, cyclic guanosine monophosphate, calcineurin, calmodulin, pERK, and pS6 increased, whereas pAkt and pCaMKII delta remained unchanged by CO. Endothelial function and systemic blood pressure were not affected by CO exposure. Long-term CO exposure reduces aerobe capacity and contractile function and leads to pathological hypertrophy. Impaired Ca2 + handling and increased growth factor signaling seem to be responsible for these pathological changes.

Zebrafish as a translational regeneration model to study the activation of neural stem cells and role of their environment

The review is an overview of the current knowledge of neuronal regeneration properties in mammals and fish. The ability to regenerate the damaged parts of the nervous tissue has been demonstrated in all vertebrates. Notably, fish and amphibians have the highest capacity for neurogenesis, whereas reptiles and birds are able to only regenerate specific regions of the brain, while mammals have reduced capacity for neurogenesis. Zebrafish (Danio rerio) is a promising model of study because lesions in the brain or complete cross-section of the spinal cord are followed by an effective neuro-regeneration that successfully restores the motor function. In the brain and the spinal cord of zebrafish, stem cell activity is always able to re-activate the molecular programs required for central nervous system regeneration. In mammals, traumatic brain injuries are followed by reduced neurogenesis and poor axonal regeneration, often insufficient to functionally restore the nervous tissue, while spinal injuries are not repaired at all. The environment that surrounds the stem cell niche constituted by connective tissue and stimulating factors, including pro-inflammation molecules, seems to be a determinant in triggering stem cell proliferation and/or the trans-differentiation of connective elements (mainly fibroblasts). Investigating and comparing the neuronal regeneration in zebrafish and mammals may lead to a better understanding of the mechanisms behind neurogenesis, and the failure of the regenerative response in mammals, first of all, the role of inflammation, considered the main inhibitor of the neuronal regeneration.

Sen34p depletion blocks tRNA splicing in vivo and delays rRNA processing

Tif6p (eIF6) is necessary for 60S biogenesis, rRNA maturation and must be released from 60S to permit 80S assembly and translation. We characterized Tif6p interactors. Tif6p is mostly on 66S-60S pre-ribosomes, partly free. Tif6p complex(es) contain nucleo-ribosomal factors and Asc1p. Surprisingly, Tif6p particle contains the low-abundance endonuclease Sen34p. We analyzed Sen34p role on rRNA/tRNA synthesis, in vivo. Sen34p depletion impairs tRNA splicing and causes unexpected 80S accumulation. Accordingly, Sen34p overexpression causes 80S decrease and increased polysomes which suggest increased translational efficiency. With delayed kinetics, Sen34p depletion impairs rRNA processing. We conclude that Sen34p is absolutely required for tRNA splicing and that it is a rate-limiting element for efficient translation. Finally, we confirm that Tif6p accompanies 27S pre-rRNA maturation to 25S rRNA and we suggest that Sen34p endonuclease in Tif6p complex may affect also rRNA maturation.

Increased phospholamban phosphorylation limits the force-frequency response in the MLP-/- mouse with heart failure

Reduced Ca(2+) release from the sarcoplasmic reticulum (SR) and a negative force-frequency relation characterize end-stage human heart failure. The MLP(-/-) mouse with dilated cardiomyopathy is used as a model to explore novel therapeutic interventions but the alterations in Ca(2+) handling in MLP(-/-) remain incompletely understood. We studied [Ca(2+)](i) in left ventricular myocytes from MLP(-/-) and WT mice (3-4 months old; whole-cell voltage clamp, 30 degrees C). At 1 Hz stimulation, the amplitude of [Ca(2+)](i) transients was similar. However, in contrast to WT, at higher frequencies the [Ca(2+)](i) transient amplitude declined in MLP(-/-) and there was no increase in SR Ca(2+) content. Unexpectedly, the decline of [Ca(2+)](i) was faster in MLP(-/-) than in WT (at 1 Hz, tau of 80 +/- 9 vs. 174 +/- 29 ms, P < 0.001) and the frequency-dependent acceleration of the decline was abolished suggesting an enhanced basal SERCA activity. Indeed, the Ca(2+) affinity of SR Ca(2+) uptake in homogenates was higher in MLP(-/-), with the maximal uptake rate similar to WT. Phosphorylation of phospholamban in MLP(-/-) was increased (2.3-fold at Ser(16) and 2.9-fold at the Thr(17) site, P < 0.001) with similar SERCA and total phospholamban protein levels. On increasing stimulation frequency to 4 Hz, WT, but not MLP(-/-), myocytes had a net gain of Ca(2+), suggesting inadequate Ca(2+) sequestration in MLP(-/-). In conclusion, increased baseline phosphorylation of phospholamban in MLP(-/-) leads to a reduced reserve for frequency-dependent increase of Ca(2+) release. This represents a novel paradigm for altered Ca(2+) handling in heart failure, underscoring the importance of phosphorylation pathways.

Bio-preservation of ground beef meat by Enterococcus faecalis CECT7121

Meat and particularly ground beef is frequently associated with Food Poisoning episodes and breeches in Food Safety. The main goal of this research was to evaluate the bactericide effect of the probiotic Enterococcus faecalis CECT7121, against different pathogens as: Escherichia coli O157:H7, Staphylococcus aureus, Clostridium perfringens and Listeria monocytogenes, inoculated in ground beef meat. Three studies were performed to evaluate the inhibition of E. faecalis CECT7121 on ground beef meat samples inoculated with pathogens: Study I: Samples (100 g meat) were inoculated with pathogens (10(3) CFU/g)) and E. faecalis CECT7121 (10(4) CFU/g) simultaneously. Study II: Samples were inoculated with E. faecalis CECT7121 24 h before the pathogens. Study III: E. faecalis CECT7121were inoculated 24 h after pathogens. The viable counts were performed at 0, 24, 48 and 72 h post-inoculation. The simultaneous inoculation of E. faecalis CECT7121 with E. coli O157:H7 strains resulted in the absence of viable counts of bacteria at 72 h post-treatment. However, when the probiotic was added 24 h before and 24 h after the pathogen E. coli O157:H7, viable cells were not detected at 24 h and 48 h post-treatment, respectively. Consistently, neither S. aureus nor Cl. perfringens viable bacteria were detected at 48 h in whole assays when inoculated with E. faecalis CECT7121. The same trend than described before was obtained after applying the 3 models assayed for L. monocytogenes. The current assays demonstrated the bactericide activity of E. faecalis CECT7121 strain on bacterial pathogens in ground beef meat.