Calcium dependent activation of the NF-AT transcription factor by p59fyn

AbstractA reporter gene under the control of a T-cell antigen receptor response element was activated in Jurkat cells by antigen receptor triggering or by a combination of phorbol myristate acetate, which activates protein kinase C, and a calcium ionophore. Both these signals were necessary for expression of the reporter gene. When co-transfected with a construct capable of overexpressing the tyrosine kinase p59fyn, the reporter gene was activated by PMA alone. Thus p59fyn could replace the calcium ionophore but not activation of protein kinase C. The activation by p59fyn plus PMA was blocked by EGTA and by the immunosuppressant drug cyclosporin A

Laparoscopic Cholecystectomy in the Cirrhotic: Review of Literature on Indications and Technique

Cholelithiasis is twice more common in patients suffering from liver cirrhosis compared to overall population and in those patients, acute cholecystitis occurs significantly more often. Our goal was to review the literature and to overview the indications, contra-indications, and alternatives in the cirrhotic with biliary stones. We conducted a systematic review of the literature using the key words "Cirrhosis", "cholecystectomy", "laparoscopy"and "indications". Selected articles were reviewed for information specific to indications, contra-indications, and alternatives to laparoscopic cholecystectomy in cirrhotics. Results showed that laparoscopic cholecystectomy might offer several advantages in cirrhotic population, however cholecystectomy can be challenging: specific indications and alternatives to surgery must be discussed case by case. Laparoscopic cholecystectomy can be performed safely in selected patients with cirrhosis; special precautions are warranted regarding pneumoperitoneum pressure, trocar placement and increased safety with Indocyanine-green (ICG) fluorescence cholangiography. Nevertheless, in high-risk cirrhotic patients (Child C) and/or in common bile duct lithiasis endoscopic and non-surgical conservative treatments are preferable

RSA, CMJ, Leger, 10m sprint responses to Pre-season training in semi-Professional Soccer Players

Aim: The aim of this study was to analyze RSA, CMJ, Leger, 10m sprint responses to Pre-season Training in Semi-Professional Soccer Players (SPSP). Considering that numerous studies1,2 highlighted the combination of high levels of physical, technical and tactical skills during a soccer match, the cure of physical training pose a particular attention on training load that generally increases up to 2.4 times during the pre-season period compared with the in-season3. Methods: Six SPSP (age: 23±7yr; BMI: 23.3±1.8) were requested to perform aerobic training over an 8-week period on alternate days with the functional strength training sessions and sprint training drills as prescribed by the coaches and strength and conditioning staff. Repeated Sprint Ability (RSA, Total Time –TT- and percentage of fatigue index -%FI), Leger, 10m sprint and Counter Mouvement Jump (CMJ) tests, were performed before and after pre-season soccer training. ANOVA for repeated measures was conducted to assess differences (p<0.05) with respect to pre seasonal training. Correlation was calculated between the percentage of variation (Δ) of each test. Results: Compared to the values recorded before the pre-season, improvement of Leger (3%) and %FI (17.6%) and a deterioration of TT (10%), 10m sprint (0.2%) and CMJ (2.4%) were found. In addition, we have found a main effect between before and after pre-seasonal training in TT (F(1,4)=60.2; p=0.001) and Leger (F(1,5)=25; p<0.005). ΔCMJ showed very large correlation with ΔLeger (r=-0.88) and nearly perfect with Δ%FI (r=0.93); while ΔLeger was largely correlated with Δ%FI (r=-0.69). Conclusions: Given that the cure of the physical preparation is considered as an important element in order to influence the final soccer game result, this study want to be useful information for the coach in order to maximize the best physical condition of the whole team relative to the beginning of the regular season

Calcium-dependent cyclosporin A-sensitive activation of the interleukin-2 promoter by p56lck.

T-cell antigen receptor engagement results in suboptimal activation of protein kinase C and a prolonged increase in intracellular free calcium concentration. These signals, in combination with stimulation via accessory molecules usually supplied by the antigen presenting cell, activate expression of interleukin-2 (IL-2) and initiate autocrine growth. The lymphocyte-specific tyrosine kinase p56lck is physically associated with CD4 and is brought into close proximity of the intracellular domain of the antigen receptor by CD4 recognition of the major histocompatibility complex during antigen presentation. p56lck activation enhances and may be essential for antigen receptor signaling. We report that a constitutively active form of p56lck delivers a signal which contributes to IL-2 promoter activation. The signal substituted for a calcium-mobilizing signal in a Jurkat cell model of T-cell activation. The activation was sensitive to EGTA and cyclosporin A, indicating that p56lck functions at an early stage of the calcium-mediated pathway. The transcription factor NF-AT mediated, at least in part, the p56lck activation of IL-2 expression. In addition, activated p56lck synergized with constitutively active p21Ha-ras, which can replace protein kinase C activation, resulting in activation of NF-AT in the absence of external signals

ras protein activity is essential for T-cell antigen receptor signal transduction.

In a Jurkat cell model of T-cell activation an interleukin-2 promoter/reporter gene construct was activated by antigen receptor agonism in combination with the lymphokine interleukin-1. Antigen receptor signals could be mimicked by suboptimal activation of protein kinase C (PKC) with phorbol esters in combination with calcium mobilization by an ionophore. In cotransfection experiments, oncogenic rats obviated the need for PKC stimulation but did not replace either the calcium signal or interleukin-1. Activated ras expression also replaced the requirement for PKC stimulation in activation of the T-cell transcription factor NF-AT. A dominant inhibitory ras mutant specifically blocked antigen receptor agonism, indicating that ras activity is required for antigen receptor signaling. In addition, an inhibitor of PKC blocked both activated ras and phorbol ester stimulation, suggesting a role for ras upstream of PKC

Interleukin-2 promoter activation in T-cells expressing activated Ha-ras.

Antigen triggering of the T-cell receptor results in an accumulation of activated GTP-bound p21ras protein. To assess the role of ras protein in T-cell activation we have cotransfected the murine thymoma line EL4 with a construct capable of expressing a constitutively active, oncogenic form of Ha-ras and a reporter construct containing the human interleukin-2 promoter fused upstream of the bacterial gene for chloramphenicol acetyltransferase. We show that the ras oncoprotein contributes to interleukin-2 promoter activation. Its pattern of synergism with a calcium ionophore or the lymphokine interleukin-1 indicates that it replaces a signal mediated by protein kinase C. Interleukin-2 promoter activity in the presence of ras oncoprotein was inhibited by H7, a potent inhibitor of protein kinase C, but not by HA1004, an inhibitor of cyclic nucleotide-dependent kinase, suggesting that protein kinase C mediates the ras effect. In addition, we show that in these cells, expression of activated ras results in activation of a synthetic promoter containing several copies of an NF kappa B binding site

Cyclosporin A blocks calcium-dependent pathways of gene activation

We have used an interleukin-2 (IL-2) promoter-CAT fusion gene to study activation of IL-2 gene expression by IL-1, phytohemagglutinin (PHA), phorbol myristate acetate (PMA), and calcium ionophore in the murine thymoma line EL4 and the human lymphoma line Jurkat. The two cell lines respond differently to combinations of these stimuli. IL-1 in combination with suboptimal concentration of PMA induced chloramphenicol acetyltransferase (CAT) activity in EL4. In Jurkat cells, IL-1 failed to synergize with PMA or PHA. Cotransfection with the IL-2/CAT gene and a construct capable of expressing murine T-cell type IL-1 receptors converted Jurkat cells to IL-1 responsiveness. IL-1 in combination with PHA but not with PMA resulted in induction of CAT activity in these cells. Induction of IL-2/CAT activity by all stimuli in both cell lines was blocked by the presence of EGTA in the culture medium. EGTA did not inhibit IL-1/PMA activation of an SV40 early promoter-CAT fusion gene in either EL4 or Jurkat cells; therefore, calcium was not required for IL-1 or PMA signal transduction. Jurkat cells were shown to differ from EL4 in their requirement for calcium mobilization. Two different calcium-dependent pathways of gene activation were distinguished, both of which were blocked by the immunosuppressive drug cyclosporin A

Physical activity and hypocaloric diet recovers osteoblasts homeostasis in women affected by abdominal obesity.

Obesity is a multifactorial disease linked to metabolic chronic disorders such as diabetes, and hypertension. Also, it has recently been associated with skeletal alterations and low bone mineral density. We previously demonstrated that exposure of osteoblasts to sera of sedentary subjects affected by obesity alters cell homeostasis in vitro, leading to disruption of intracellular differentiation pathways and cellular activity. Thus, the purpose of the present study has been to evaluate whether sera of sedentary obese women, subjected to physical activity and hypocaloric diet, could recover osteoblast homeostasis in vitro as compared to the sera of same patients before intervention protocol. To this aim, obese women were evaluated at time 0 and after 4, 6, and 12 months of individualized prescribed physical activity and hypocaloric diet. Dual-energy-X-ray absorptiometry measurements were performed at each time point, as well as blood was collected at the same points. Cells were incubated with sera of subjects before and after physical activity as described: obese at baseline and after for 4, 6, and 12 months of physical activity and nutritional protocol intervention. Osteoblasts exposed to sera of patients, who displayed increased lean and decreased fat mass (from 55.5 ± 6.5 to 57.1 ± 5.6% p ≤ 0.05; from 44.5 ± 1.1 to 40.9 ± 2.6% p ≤ 0.01 respectively), showed a time-dependent increase of Wnt/β-catenin signaling, versus cells exposed to sera of obese patients before intervention protocol, suggesting recovery of osteoblast homeostasis upon improvement of body composition. An increase in β-catenin nuclear accumulation and nuclear translocation was also observed, accompanied by an increase in Adiponectin receptor 1 protein expression, suggesting positive effect on cell differentiation program. Furthermore, a decrease in sclerostin amount and an increase of type 1 procollagen amino-terminal-propeptide were depicted as compared to baseline, proportionally to the time of physical activity, suggesting a recovery of bone remodeling modulation and an increase of osteoblast activity induced by improvement of body composition. In conclusion, our results show for the first time that sera of obese sedentary women who increased lean mass and decreased fat mass, by physical activity and hypocaloric diet, rescue osteoblasts differentiation and activity likely due to a reactivation of Wnt/β-catenin-pathway, suggesting that a correct life style can improve skeletal metabolic alteration induced by obesity