Endoplasmic Reticulum Stress in Heat- and Shake-Induced Injury in the Rat Small Intestine

We investigated the mechanisms underlying damage to rat small intestine in heat- and shake-induced stress. Eighteen Sprague-Dawley rats were randomly divided into a control group and a 3-day stressed group treated 2 h daily for 3 days on a rotary platform at 35°C and 60 r/min. Hematoxylin and eosin-stained paraffin sections of the jejunum following stress revealed shedding of the villus tip epithelial cells and lamina propria exposure. Apoptosis increased at the villus tip and extended to the basement membrane. Photomicrographs revealed that the microvilli were shorter and sparser; the nuclear envelope invaginated and gaps in the karyolemma increased; and the endoplasmic reticulum (ER) swelled significantly. Gene microarray analysis assessed 93 differentially expressed genes associated with apoptosis, ER stress, and autophagy. Relevant genes were compiled from the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Forty-one genes were involved in the regulation of apoptosis, fifteen were related to autophagy, and eleven responded to ER stress. According to KEGG, the apoptosis pathways, mitogen-activated protein kinase(MAPK) signaling pathway, the mammalian target of rapamycin (mTOR) signaling pathway, and regulation of autophagy were involved. Caspase3 (Casp3), caspase12 (Casp12), and microtubule-associate proteins 1 light chain 3(LC3) increased significantly at the villus tip while mTOR decreased; phosphorylated-AKT (P-AKT) decreased. ER stress was involved and induced autophagy and apoptosis in rat intestinal damage following heat and shake stress. Bioinformatic analysis will help determine the underlying mechanisms in stress-induced damage in the small intestine.

Caspase-12 silencing attenuates inhibitory effects of cigarette smoke extract on NOD1 signaling and hBDs expression in human oral mucosal epithelial cells

Cigarette smoke exposure is associated with increased risk of various diseases. Epithelial cells-mediated innate immune responses to infectious pathogens are compromised by cigarette smoke. Although many studies have established that cigarette smoke exposure affects the expression of Toll-liked receptor (TLR), it remains unknown whether the nucleotide-binding oligomerization domain-containing protein 1 (NOD1) expression is affected by cigarette smoke exposure. In the study, we investigated effects of cigarette smoke extract (CSE) on NOD1 signaling in an immortalized human oral mucosal epithelial (Leuk-1) cell line. We first found that CSE inhibited NOD1 expression in a dose-dependent manner. Moreover, CSE modulated the expression of other crucial molecules in NOD1 signaling and human β defensin (hBD) 1, 2 and 3. We found that RNA interference-induced Caspase-12 silencing increased NOD1 and phospho-NF-κB (p-NF-κB) expression and down-regulated RIP2 expression. The inhibitory effects of CSE on NOD1 signaling can be attenuated partially through Caspase-12 silencing. Intriguingly, Caspase-12 silencing abrogated inhibitory effects of CSE on hBD1, 3 expression and augmented induced effect of CSE on hBD2 expression. Caspase-12 could play a vital role in the inhibitory effects of cigarette smoke on NOD1 signaling and hBDs expression in oral mucosal epithelial cells.

[Effects of adipose-derived stem cells transplantation on the neuronal apoptosis and the expression of Bcl-2 and caspase-12 in the brain post focal cerebral ischemia in rats]

AIM

To investigate the effects of adipose-derived stem cells (ADSCs) transplantation on neuronal apoptosis in the brain after focal cerebral ischemia in rats.

METHODS

72 male adult Sprague-Dawley rats were randomly divided into 4 groups: Sham-operated group , Middle cerebral artery occlusion (MCAO) group, Vehicle group and ADSC-treated group (n=18). MCAO model was established with the modified Longa's method. One day after right MCAO, 30 μL of cell suspension containing 1×10(6); cells were injected into the lateral ventricle of ADSC-treated group and the same dose of PBS was given to the vehicle group. At 4 d, 7 d and 14 d after MCAO, the apoptosis of neuron was detected by terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling (TUNEL) method and the expression of Bcl-2 and caspase-12 in ischemic region was detected by immunohistochemistry and RT-PCR.

RESULTS

TUNEL-positive cells in ischemic region of ADSC-treated group were less than that in MCAO group and Vehicle group at 4 d, 7 d and 14 d post MCAO (P<0.05). Compared with MCAO group and Vehicle group, the expression of Bcl-2 significantly up-regulated while caspase-12 expression significantly decreased in ADSC-treated group at any time point post MCAO (P<0.05).

CONCLUSION

The transplantation of ADSCs can reduce neuronal apoptosis of rats with cerebral ischemic injury partly by promoting the expression of Bcl-2 which participates in apoptotic signals after mitochondrial damage and inhibiting the expression of caspase-12 which mediates endoplasmic reticulum (ER) stress-induced apoptosis.

Ageing enhances alpha-synuclein, ubiquitin and endoplasmic reticular stress protein expression in the nigral neurons of Asian Indians

Accumulating evidences suggest that dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc) during ageing and in Parkinson's disease (PD) is linked to neurodegenerative changes like exponential increase in alpha-synuclein expression and protein misfolding. Lewy body formation is also a quintessential observation in neurodegeneration and PD. In experimental models of PD, GRP78 a neuroprotective endoplasmic reticulum (ER) chaperone protein targets misfolded proteins for degradation and prevents release of caspase12 from the ER. Release of active caspase12 and its translocation to the nucleus induces ER mediated apoptosis. The effect of ageing on these proteins in human nigra is not known. We evaluated alpha-synuclein, caspase12, GRP78 and ubiquitin expression in the SNpc of Asian Indians, using immunohistochemistry and stereology. The number of alpha-synuclein and caspase12 immunoreactive neurons increased gradually with age whereas the number of GRP78-labeled neurons remained stable. In contrast, GRP78 protein expression was significantly upregulated with age, while alpha-synuclein and caspase12 increased slightly. An increase in the size and numbers of marinesco bodies was prominent after the sixth decade. The mild increase in alpha-synuclein expression and occurrence of marinesco bodies suggests ageing induced protein misfolding and GRP78 upregulation indicates presence of ER stress. The logarithmic upregulation of GRP78 could even be an indicator of neuroprotective or neuromodulatory response of ER to protein misfolding and initiation of unfolded protein response pathway. Since dopaminergic neurons are preserved in ageing Asian Indians, our study possibly signifies better proteasomal or ER response and partially explains the lower prevalence of PD in them.

Matrix metalloproteinase-3 is increased and participates in neuronal apoptotic signaling downstream of caspase-12 during endoplasmic reticulum stress

Although endoplasmic reticulum (ER) stress-induced apoptosis has been associated with pathogenesis of neurodegenerative diseases, the cellular components involved have not been well delineated. The present study shows that matrix metalloproteinase (MMP)-3 plays a role in the ER stress-induced apoptosis. ER stress induced by brefeldin A (BFA) or tunicamycin (TM) increases gene expression of MMP-3, selectively among various MMP subtypes, and the active form of MMP-3 (actMMP-3) in the brain-derived CATH.a cells. Pharmacological inhibition of enzyme activity, small interference RNA-mediated gene knockdown, and gene knock-out of MMP-3 all provide protection against ER stress. MMP-3 acts downstream of caspase-12, because both pharmacological inhibition and gene knockdown of caspase-12 attenuate the actMMP-3 increase, but inhibition and knock-out of MMP-3 do not alter caspase-12. Furthermore, independently of the increase in the protein level, the catalytic activity of MMP-3 enzyme can be increased via lowering of its endogenous inhibitor protein TIMP-1. Caspase-12 causes liberation of MMP-3 enzyme activity by degrading TIMP-1 that is already bound to actMMP-3. TIMP-1 is decreased in response to ER stress, and TIMP-1 overexpression leads to cell protection and a decrease in MMP-3 activity. Taken together, actMMP-3 protein level and catalytic activity are increased following caspase-12 activation during ER stress, and this in turn plays a role in the downstream apoptotic signaling in neuronal cells. MMP-3 and TIMP-1 may therefore serve as cellular targets for therapy against neurodegenerative diseases.

Cocaine increases immunoglobulin heavy chain binding protein and caspase-12 expression in the rat dorsal striatum

RATIONALE

Cocaine increases endoplasmic reticulum (ER) stress protein expression via glutamate and dopamine receptor activation in the dorsal striatum.

OBJECTIVES

The present study was performed to investigate ER stress response in the dorsal striatum in response to acute or repeated cocaine stimulation. It was hypothesized that cocaine upregulates the ER stress protein immunoglobulin heavy chain binding protein (BiP) and the ER stress-associated protein caspase-12 via N-methyl-D-aspartate (NMDA) and D1 dopamine receptor activation.

MATERIALS AND METHODS

Western immunoblot and immunohistochemical analyses were mainly performed to test this hypothesis in the rat dorsal striatum.

RESULTS

The results showed that BiP and caspase-12 immunoreactivities were significantly increased at 30, 60, and 120 min after acute or repeated intraperitoneal (i.p.) injections of three doses (10, 20, 40 mg/kg) of cocaine for seven consecutive days. Intrastriatal (i.s.) infusion of the selective NMDA antagonist MK801 (2 nmol) or AP5 (2 nmol) significantly attenuated the increase in the immunoreactivity of caspase-12 in the dorsal striatum induced by repeated, but not acute, cocaine (20 mg/kg) administration. However, i.p. injection of the selective D1 antagonist SCH23390 (0.1 mg/kg) significantly attenuated the increase in the immunoreactivity of caspase-12 in the dorsal striatum induced by both acute and repeated cocaine (20 mg/kg) stimulation.

CONCLUSION

These findings suggest that acute or repeated cocaine administration can cause ER stress response in the dorsal striatum in which NMDA and D1 dopamine receptors participate in the mediation of the process.

Calpain Inhibition but not Reticulum Endoplasmic Stress Preconditioning Protects Rat Kidneys from p-Aminophenol Toxicity

p-Aminophenol (pAP, 225 mg/kg) administration to rats induced renal failure and has been associated with markers of endoplasmic reticulum (ER) stress, as well as calpain and caspase-12 activation in kidneys. To determine the importance of ER stress and calpain during pAP-induced nephrotoxicity, rats were pretreated with low, nontoxic, doses of ER stress inducers or with the selective calpain inhibitor PD150606 (3 mg/kg). Prior ER stress induced by tunicamycin and oxidized dithiothreitol did not result in protection against renal failure, but PD150606 administration was protective and decreased significantly the rise in creatinine and blood urea nitrogen observed after 24-h post-pAP administration. pAP-induced XBP1 upregulation was not modified by calpain inhibition, but a trend to lower GRP94 induction was determined, suggesting that pAP-induced ER stress was mostly calpain independent. In contrast, pAP-induced caspase-12 cleavage products were significantly decreased with PD150606 pretreatment, demonstrating that caspase-12 activation was calpain dependent. This study reveals the importance of calpain in pAP-induced renal failure. Further research with other nephrotoxicants needs to be performed to determine if calpain activation is a common feature of drug-induced renal failure.

[Apoptosis and caspase-12 expression in progressive compressive spinal cord injury: experiment with rats]

OBJECTIVE

To investigate the apoptosis and caspase-12 expression in progressive compression of spinal cord (PCSC).

METHODS

120 adult Wistar rats were randomly divided into 2 equal groups, experimental group, undergoing operation so as to establish PCSC models, and control group, undergoing sham operation. 1, 3, 7, 14, 21, and 28 days after the operation, 5 rats from each group were anesthetized with their spinal cords taken out. TUNNEL method was used to observe the apoptosis of the neurons in the compressed segments. Another 5 rats from each group at different time points were anesthetized with their spinal cords as well. Immunohistochemistry was used to detect the mRNA expression of caspase-12 in the compressed segments. Western blotting was used to detect the protein expression of caspase-12.

RESULTS

The apoptotic rates of neurons and gliocytes 1, 3, 7, 14, 21, and 28 days after were 12.5% +/- 2.3%, 13.0% +/- 3.6%, 17.2% +/- 4.3%, 29.4% +/- 4.4%, 36.1% +/- 6.5%, and 2.3% +/- 7.9% respectively, with significant differences among the values 14, 21, and 28 days and those at other time points after the operation (all P < 0.05). Immunohistochemistry showed that the number of caspase-12 positive neurons increased since 1 day after, and became remarkably high 14, 21, and 28 days after with significant differences among different time points (all P < 0.05). Western blotting showed that the protein expression of caspase-12 was low 1, 3, and 7 days after, and peaked 14 days after, and then gradually decreased, however, the expression levels 21 and 28 days after were still significantly higher then those 1, 3, and 7 days after (all P < 0.05).

CONCLUSION

Caspase-12 is involved in the apoptosis of neurons in PCSC.

[Inhibition of mouse hepatocyte apoptosis by anti-caspase-12 small interfering RNA]

OBJECTIVES

To study the inhibition of primary mouse hepatocyte apoptosis by small interfering RNA (siRNAs) against caspase-12.

METHODS

The Balb/c mouse primary hepatocytes were isolated in situ with two-step liver perfusion with 0.5 g/L collagenase type IV, and apoptosis were induced with 4 micromol/L thapsigargin (TG). The three kingds of siRNAs targeting different gene sites (130, 214, 521) were synthetized chemically. The single-stranded RNAs were annealed to produce double-stranded siRNAs, then the mouse primary hepatocytes were transfected by oligofectamine package. The inhibition of caspase-12 was analyzed with RT-PCR and Western-blot. The viable hepatocytes following the induction of apoptosis were evaluated with MTT.

RESULTS

All the three kinds of siRNAs could obviously inhibit normal mouse hepatocyte caspase-12 mRNA. The siRNA (214) were more effective than the other two when the concentration was 100 nmol/L. The caspase-12 mRNA expression was inhibited by 52.08%, while that of siRNA (521) was 30.73% (t=4.30, P <0.05). However when the concentration was 200 nmol/L, the inhibitions were similar (88.07%, 86.22% and 89.41% respectively). siRNA (214) could downregulate the expression of apoptotic hepatocytes procaspase-12 by 51.43% ( t=4.30, P <0.01). Contrasted with apoptotic hepatocytes, the cell activity, which was analyzed with MTT, increased by 48.76% (t=2.23, P <0.01).

CONCLUSION

siRNAs could effectively downregulate the expression of caspase-12 at mRNA and protein levels and prevent mouse primary hepatocytes from apoptosis.

[Caspase-12 expression and activation in the pathogenesis of acute hepatic failure induced by lipopolysaccharide and D-galactosamine]

OBJECTIVE

To study the role of caspase-12 expression on hepatocyte apoptosis in an experimental model of acute hepatic failure (AHF).

METHODS

A mouse experimental model of AHF was developed by intraperitoneal injection of lipopolysaccharide (LPS) and D-galactosamine (D-Gal). Hepatocyte apoptosis was examined by DNA agarose gel and liver pathology. Caspase-12 mRNA expression in liver was detected by reverse transcriptase PCR (RT-PCR) method. The expression of caspase-12, GRP78 proteins in livers was determined by Western blot.

RESULTS

Caspase-12 mRNA expression in the livers increased significantly from 5 to 7 hours after administration of LPS and D-Gal. Typical manifestation of hepatocyte apoptosis appeared at 5 hours after the drug administration. After 5 hours the level of serum ALT and AST were remarkably increased, and they reached the peak at 7 hours. The expression of procaspase-12 protein decreased obviously at 7 hours. Seven hours after the drug administration, hepatocyte apoptosis and necrosis both started. The marker of endoplasmic reticulum (ER) stress, Bip/GRP78 was activated during the development of hepatocyte apoptosis. The level of Bip/GRP78 protein was gradually increased at 5 hours after the drug induction.

CONCLUSION

Hepatocyte apoptosis plays an important role in the pathogenesis of AHF. Caspase-12 induced ER stress involves in hepatocyte apoptosis. It suggests that inhibition of caspase-12 activation might be a potential strategy in the treatment of AHF in the future.