Short-chain fatty acids induced autophagy serves as an adaptive strategy for retarding mitochondria-mediated apoptotic cell death

Short-chain fatty acids (SCFAs) are the major by-products of bacterial fermentation of undigested dietary fibers in the large intestine. SCFAs, mostly propionate and butyrate, inhibit proliferation and induce apoptosis in colon cancer cells, but clinical trials had mixed results regarding the anti-tumor activities of SCFAs. Herein we demonstrate that propionate and butyrate induced autophagy in human colon cancer cells to dampen apoptosis whereas inhibition of autophagy potentiated SCFA induced apoptosis. Colon cancer cells, after propionate treatment, exhibited extensive characteristics of autophagic proteolysis: increased LC3-I to LC3-II conversion, acidic vesicular organelle development, and reduced p62/SQSTM1 expression. Propionate-induced autophagy was associated with decreased mTOR activity and enhanced AMP kinase activity. The elevated AMPKα phosphorylation was associated with cellular ATP depletion and overproduction of reactive oxygen species due to mitochondrial dysfunction involving the induction of MPT and loss of Δψ. In this context, mitochondria biogenesis was initiated to recover cellular energy homeostasis. Importantly, when autophagy was prevented either pharmacologically (3-MA or chloroquine) or genetically (knockdown of ATG5 or ATG7), the colon cancer cells became sensitized toward propionate-induced apoptosis through activation of caspase-7 and caspase-3. The observations indicate that propionate-triggered autophagy serves as an adaptive strategy for retarding mitochondria-mediated apoptotic cell death, whereas application of an autophagy inhibitor (Chloroquine) is expected to enhance the therapeutic efficacy of SCFAs in inducing colon tumor cell apoptosis.

CBP80-promoted mRNP rearrangements during the pioneer round of translation, nonsense-mediated mRNA decay, and thereafter

In mammalian cells, two different messenger ribonucleoproteins (mRNPs) serve as templates for protein synthesis. Newly synthesized mRNPs bound by the cap-binding protein heterodimer CBP80-CBP20 (CBC) initially undergo a pioneer round of translation. One purpose of this round of translation is to ensure the quality of gene expression, as exemplified by nonsense-mediated messenger RNA (mRNA) decay (NMD). NMD largely functions to eliminate mRNAs that prematurely terminate translation, although NMD also contributes to proper gene control, and it targets CBC-bound mRNPs. CBC-bound mRNPs are remodeled to eukaryotic translation initiation factor (eIF)4E-bound mRNPs in steps that (1) are a consequence of the pioneer round of translation and (2) occur independently of translation. Rather than supporting NMD, eIF4E-bound mRNPs provide for the bulk of cellular protein synthesis and are the primary targets of mRNA decay mechanisms that conditionally regulate gene expression. Here, we overview cellular processes by which CBC-bound mRNPs are remodeled to eIF4E-bound mRNPs. We also describe the molecular movements of certain factors during NMD in view of the influential role of CBP80.

Let-7/miR-98 regulate Fas and Fas-mediated apoptosis

Fas is ubiquitously expressed on a variety of cells and triggers apoptosis, which have critical roles in the immune system. MicroRNAs (miRNAs) have been recently identified as regulators that modulate target gene expression and are involved in diverse biological processes, such as cell proliferation and apoptosis. This study was undertaken to investigate the contribution of miRNA in the regulation of Fas expression and Fas-mediated apoptosis. Bioinformatics analysis indicated that Fas was a potential target of let-7/miR-98 family. Indeed ectopic expression of let-7/miR-98 reduced, whereas knockdown of endogenous let-7/miR-98 increased the expression of Fas at both mRNA and protein levels. Let-7/miR-98 was verified to target Fas 3' untranslated region directly by site-directed gene mutagenesis and reporter gene assay. More importantly, introduction of let-7/miR-98 could decrease the sensitivity to Fas-induced apoptosis. Furthermore, let-7/miR-98 expression was reduced in activation-induced cell death process, accompanied by increased expression of Fas. In conclusion, our study first demonstrated that let-7/miR-98 regulated Fas expression and the sensitivity of Fas-mediated apoptosis.

A randomized prospective study of rehabilitation therapy in the treatment of radiation-induced dysphagia and trismus

PURPOSE

To evaluate the therapeutic effect of rehabilitation therapy on radiation-induced dysphagia and trismus in nasopharyngeal carcinoma (NPC) patients after radiotherapy.

PATIENTS AND METHODS

43 NPC patients after radiotherapy were included. Patients were randomly assigned to either the rehabilitation group or a control group. Both groups were subjected to routine treatment, while the rehabilitation group also received rehabilitation therapy for 3 months. The severity of dysphagia was assessed using the water swallow test, while trismus was evaluated with the LENT/SOMA score and the interincisor distance (IID). The water swallow test, the LENT/SOMA score, as well as IID for both groups before and after treatment were analyzed and compared.

RESULTS

After treatment, the rehabilitation group displayed a significant improvement in swallowing function, while the control group did not. The efficacy rate (percentage of patients with excellent or effective results) of rehabilitation group was higher than that of control group (77% vs. 43%), and the difference was statistically significant (ϰ(2) = 5.32, p = 0.02). IID pretreatment and posttreatment did not show much difference in the rehabilitation group, while in the control group IID significantly decreased posttreatment (1.1 ± 0.36 cm vs.1.8 ± 0.56 cm, p = 0.001). Although the mean IID in patients of both groups decreased after the 3 month follow-up, the decrease in the rehabilitation group was less than that of the control group (0.19 ± 0.5 cm vs. 0.69 ± 0.56 cm, p = 0.004 ). The efficacy rate of trismus in the rehabilitation group was significantly higher than that of the control group (64% vs. 28%, ϰ(2) = 5.31, p = 0.02).

CONCLUSIONS

Rehabilitation training can improve swallow function and slow down the progress of trismus in NPC patients following radiotherapy.

[One-stage posterior approach and pedicle instrumentation for correction of scoliosis associated with Chiari I malformation in adolescent]

OBJECTIVE

To analyze the clinical features of scoliosis associated with Chiari I malformation in adolescent patients, and to explore the validity and safety of one-stage posterior approach and vertebral column resection for the correction of severe scoliosis.

METHODS

Between October 2004 and August 2008, 17 adolescent patients with scoliosis associated with Chiari I malformation were treated with surgical correction through posterior approach and pedicle instrumentation. There were 9 males and 8 females with an average age of 15.1 years (range, 12-19 years). The MRI scanning showed that 16 of 17 patients had syringomyelia in cervical or thoracic spinal cord. Apex vertebra of scoliosis were located at T7-12. One-stage posterior vertebral column resection and instrumental correction were performed on 9 patients whose Cobb angle of scoliosis or kyphosis was more than 90 degrees, or who was associated with apparent neurological deficits (total spondylectomy group). Other 8 patients underwent posterior instrumental correction alone (simple correction group). All patients' fixation and fusion segment ranged from upper thoracic spine to lumbar spine.

RESULTS

The operative time and the blood loss were (384 +/- 65) minutes and (4 160 +/- 336) mL in total spondylectomy group, and were (246 +/- 47) minutes and (1 450 +/- 213) mL in simple correction group; showing significant differences (P < 0.05). In total spondylectomy group, coagulation disorder occurred in 1 case, pleural perforation in 4 cases, and lung infection in 1 case. In simple correction group, pleural perforation occurred in 1 case. These patients were improved after symptomatic treatment. All patients were followed up 24-36 months (32.5 months on average). Bony healing was achieved at 6-12 months in total spondylectomy group. No breakage or pulling-out of internal fixator occurred. The angles of kyphosis and scoliosis were significantly improved at 1 week after operation (P < 0.01) when compared with those before operation. The correction rates of scoliosis and kyphosis (63.4% +/- 4.6% and 72.1% +/- 5.8%) in total spondylectomy group were better than those (69.4% +/- 17.6% and 48.8% +/- 19.3%) in simple correction group.

CONCLUSION

Suboccipital decompression before spine deformity correction may not always be necessary in adolescent scoliosis patients associated with Chiari I malformation. In patients with severe and rigid curve or apparente neurological deficits, posterior vertebral column resection would provide the opportunity of satisfied deformity correction and decrease the risk of neurological injury connected with surgical correction.

Defective Ca(2+) handling proteins regulation during heart failure

Abnormal release of Ca(2+) from sarcoplasmic reticulum (SR) via the cardiac ryanodine receptor (RyR2) may contribute to contractile dysfunction in heart failure (HF). We previously demonstrated that RyR2 macromolecular complexes from HF rat were significantly more depleted of FK506 binding protein (FKBP12.6). Here we assessed expression of key Ca(2+) handling proteins and measured SR Ca(2+) content in control and HF rat myocytes. Direct measurements of SR Ca(2+) content in permeabilized cardiac myocytes demonstrated that SR luminal [Ca(2+)] is markedly lowered in HF (HF: DeltaF/F(0) = 26.4+/-1.8, n=12; control: DeltaF/F(0) = 49.2+/-2.9, n=10; P<0.01). Furthermore, we demonstrated that the expression of RyR2 associated proteins (including calmodulin, sorcin, calsequestrin, protein phosphatase 1, protein phosphatase 2A), Ca(2+) ATPase (SERCA2a), PLB phosphorylation at Ser16 (PLB-S16), PLB phosphorylation at Thr17 (PLB-T17), L-type Ca(2+) channel (Cav1.2) and Na(+)- Ca(2+) exchanger (NCX) were significantly reduced in rat HF. Our results suggest that systolic SR reduced Ca(2+) release and diastolic SR Ca(2+) leak (due to defective protein-protein interaction between RyR2 and its associated proteins) along with reduced SR Ca(2+) uptake (due to down-regulation of SERCA2a, PLB-S16 and PLB-T17), abnormal Ca(2+) extrusion (due to down-regulation of NCX) and defective Ca(2+) -induced Ca(2+) release (due to down-regulation of Cav1.2) could contribute to HF.

Differentiation of ruminant transmissible spongiform encephalopathy isolate types, including bovine spongiform encephalopathy and CH1641 scrapie

With increased awareness of the diversity of transmissible spongiform encephalopathy (TSE) strains in the ruminant population, comes an appreciation of the need for improved methods of differential diagnosis. Exposure to bovine spongiform encephalopathy (BSE) has been associated with the human TSE, variant Creutzfeldt-Jakob disease, emphasizing the necessity in distinguishing low-risk TSE types from BSE. TSE type discrimination in ruminants such as cattle, sheep, goats and deer, requires the application of several prion protein (PrP)-specific antibodies in parallel immunochemical tests on brain homogenates or tissue sections from infected animals. This study uses in a single incubation step, three PrP-specific antibodies and fluorescent Alexa dye-labelled anti-mouse Fabs on a Western blot. The usual amount of brain tissue needed is 0.5 mg. This multiplex application of antibodies directed towards three different PrP epitopes enabled differential diagnosis of all established main features of classical scrapie, BSE and Nor98-like scrapie in sheep and goats, as well as the currently known BSE types C, H and L in cattle. Moreover, due to an antibody-dependent dual PrP-banding pattern, for the first time CH1641 scrapie of sheep can be reliably discriminated from the other TSE isolate types in sheep.