Rottlerin Enhances the Autophagic Degradation of Phosphorylated Tau in Neuronal Cells

Intra-neuronal accumulation of hyper-phosphorylated tau as neurofibrillary tangles (NFT) is a hallmark of Alzheimer's disease (AD). To prevent the aggregation of phosphorylated tau in neurons, decreasing the phosphorylated tau protein levels is important. Here, we examined the biological effects of rottlerin, a phytochemical compound extracted from the Kamala tree, Mallotus philippinensis, on phosphorylated tau levels. Notably, rottlerin decreased the levels of intracellular phosphorylated and total tau. A marked increase in the LC3-II, a hallmark of autophagy, was observed in these cells, indicating that rottlerin strongly induced autophagy. Interestingly, rottlerin induced the phosphorylation of Raptor at S792 through the activation of adenosine-monophosphate activated-protein kinase (AMPK), which likely inhibits the mammalian target of rapamycin complex 1 (mTORC1), thus resulting in the activation of transcription factor EB (TFEB), a master regulator of autophagy. In addition, nuclear factor erythroid 2-related factor 2 (Nrf2) activity increased in the presence of rottlerin. The decrease of phosphorylated tau levels in the presence of rottlerin was ameliorated by the knockdown of TFEB and partially attenuated by the knockout of the Nrf2 gene. Taken together, rottlerin likely enhances the degradation of phosphorylated tau through autophagy activated by TFEB and Nrf2. Thus, our results suggest that a natural compound rottlerin could be used as a preventive and therapeutic drug for AD.

Effects of genomic estimated breeding value and dietary energy to protein ratio on growth performance, carcass trait, and lipogenic gene expression in Hanwoo steer

"Genome-based precision feeding" is a concept that involves the application of customised diets to different genetic groups of cattle. We investigated the effects of the genomic estimated breeding value (gEBV) and dietary energy to protein ratio (DEP) on growth performance, carcass traits, and lipogenic gene expression in Hanwoo (Korean cattle) steers. Forty-four Hanwoo steers (BW = 636 kg, age = 26.9 months) were genotyped using the Illumina Bovine 50 K BeadChip. The gEBV was calculated using genomic best linear unbiased prediction. Animals were separated into high gEBV of marbling score or low-gMS groups based on the upper and lower 50% groupings of the reference population, respectively. Animals were assigned to one of four groups in a 2 × 2 factorial arrangement: high gMS/high DEP (0.084 MJ/g), high gMS/low DEP (0.079 MJ/g), low gMS/high DEP, and low gMS/low DEP. Steers were fed concentrate with a high or low DEP for 31 weeks. The BW tended to be higher (0.05 < P < 0.1) in the high-gMS groups compared to the low-gMS groups at 0, 4, 8, 12, and 20 weeks. The average daily gain (ADG) tended to be lower (P = 0.08) in the high-gMS group than in the low-gMS group. Final BW and measured carcass weight (CW) were positively correlated with the gEBV of carcass weight (gCW). The DEP did not affect ADG. Neither the gMS nor the DEP affected the MS and beef quality grade. The intramuscular fat (IMF) content in the longissimus thoracis (LT) tended to be higher (P = 0.08) in the high-gMS groups than in the low-gMS groups. The mRNA levels of lipogenic acetyl-CoA carboxylase and fatty acid binding protein 4 genes in the LT were higher (P < 0.05) in the high-gMS group than in the low-gMS group. Overall, the IMF content tended to be affected by the gMS, and the genetic potential (i.e., gMS) was associated with the functional activity of lipogenic gene expression. The gCW was associated with the measured BW and CW. The results demonstrated that the gMS and the gCW may be used as early prediction indexes for meat quality and growth potential of beef cattle.

Altered TIMP-3 Levels in the Cerebrospinal Fluid and Plasma of Patients with Alzheimer’s Disease

Tissue inhibitor of metalloproteinase-3 (TIMP-3) is a component of the extracellular environment and is suggested to play an indirect role in regulating Aβ production and the pathophysiology of Aβ deposition in brains. However, studies on the amount of TIMP-3 in bodily fluids of Alzheimer’s disease (AD) patients have not been conducted. Here, we investigated the relationship between fluid TIMP-3 levels and AD pathology. We first showed that the fluid levels of TIMP-3 were lower in AD dementia patients compared with in non-AD patients. ELISA results revealed that plasma levels of TIMP-3 in 65 patients with AD were significantly lower than those in 115 healthy control subjects and 71 mild cognitive impairment (MCI) subjects. Furthermore, we found that cerebrospinal fluid (CSF) level of TIMP-3 was decreased in AD compared with that in healthy control. These data suggest that fluid TIMP-3 levels negatively correlated with progress of cognitive decline. Collectively, our study suggests that alterations of fluid TIMP-3 levels might be associated with AD pathology.

ApoE4 attenuates autophagy via FoxO3a repression in the brain

Apolipoprotein E (ApoE) plays multiple roles in lipid transport, neuronal signaling, glucose metabolism, mitochondrial function, and inflammation in the brain. It is also associated with neurodegenerative diseases, and its influence differs depending on the isoform. In particular, the ε4 allele of APOE is the highest genetic risk factor for developing late-onset Alzheimer's disease (AD). However, the mechanism by which ApoE4 contributes to the pathogenesis of AD remains unclear. We investigated the effect of ApoE4 on autophagy in the human brains of ApoE4 carriers. Compared to non-carriers, the expression of FoxO3a regulating autophagy-related genes was significantly reduced in ApoE4 carriers, and the phosphorylation level of FoxO3a at Ser253 increased in ApoE4 carriers, indicating that FoxO3a is considerably repressed in ApoE4 carriers. As a result, the protein expression of FoxO3a downstream genes, such as Atg12, Beclin-1, BNIP3, and PINK1, was significantly decreased, likely leading to dysfunction of both autophagy and mitophagy in ApoE4 carriers. In addition, phosphorylated tau accumulated more in ApoE4 carriers than in non-carriers. Taken together, our results suggest that ApoE4 might attenuate autophagy via the repression of FoxO3a in AD pathogenesis. The regulation of the ApoE4-FoxO3a axis may provide a novel therapeutic target for the prevention and treatment of AD with the APOE4 allele.

Curcumin activates Nrf2 through PKCδ-mediated p62 phosphorylation at Ser351

Curcumin, a phytochemical extracted from Curcuma longa rhizomes, is known to be protective in neurons via activation of Nrf2, a master regulator of endogenous defense against oxidative stress in cells. However, the exact mechanism by which curcumin activates Nrf2 remains controversial. Here, we observed that curcumin induced the expression of genes downstream of Nrf2 such as HO-1, NQO1, and GST-mu1 in neuronal cells, and increased the level of Nrf2 protein. Notably, the level of p62 phosphorylation at S351 (S349 in human) was significantly increased in cells treated with curcumin. Additionally, curcumin-induced Nrf2 activation was abrogated in p62 knockout (−/−) MEFs, indicating that p62 phosphorylation at S351 played a crucial role in curcumin-induced Nrf2 activation. Among the kinases involved in p62 phosphorylation at S351, PKCδ was activated in curcumin-treated cells. The phosphorylation of p62 at S351 was enhanced by transfection of PKCδ expression plasmid; in contrast, it was inhibited in cells treated with PKCδ-specific siRNA. Together, these results suggest that PKCδ is mainly involved in curcumin-induced p62 phosphorylation and Nrf2 activation. Accordingly, we demonstrate for the first time that curcumin activates Nrf2 through PKCδ-mediated p62 phosphorylation at S351.

Elevated Cerebrospinal Fluid and Plasma N-Cadherin in Alzheimer Disease

N-cadherin is a synaptic adhesion molecule stabilizing synaptic cell structure and function. Cleavage of N-cadherin by γ-secretase produces a C-terminal fragment, which is increased in the brains of Alzheimer disease (AD) patients. Here, we investigated the relationship between fluid N-cadherin levels and AD pathology. We first showed that the cleaved levels of N-cadherin were increased in homogenates of postmortem brain from AD patients compared with that in non-AD patients. We found that cleaved N-cadherin levels in the cerebrospinal fluid were increased in AD dementia compared with that in healthy control. ELISA results revealed that plasma levels of N-cadherin in 76 patients with AD were higher than those in 133 healthy control subjects. The N-cadherin levels in the brains of an AD mouse model, APP Swedish/PS1delE9 Tg (APP Tg) were reduced compared with that in control. The N-terminal fragment of N-cadherin produced by cleavage at a plasma membrane was detected extravascularly, accumulated in senile plaques in the cortex of an APP Tg mouse. In addition, N-cadherin plasma levels were increased in APP Tg mice. Collectively, our study suggests that alteration of N-cadherin levels might be associated with AD pathology.

Association between blood lead level and risk of stroke in Korean adults: a cross-sectional study in the Korea National Health and Nutrition Examination Survey 2008-2013

OBJECTIVES

Although lead is a potential risk factor for cardiovascular diseases such as stroke, research on this association in the Korean population remains limited. Therefore, we aimed to investigate the association between lead level and stroke in Korean adults.

DESIGN

A population-based cross-sectional study.

SETTING

The Korea National Health and Nutrition Examination Survey 2008-2013, which enrolled a representative sample of the Korean population.

PARTICIPANTS

We excluded participants younger than 20 years, missing weight data, pregnant or lactating, and missing blood lead and stroke data. A total of 11 510 participants were included in this analysis.

PRIMARY AND SECONDARY OUTCOME MEASUREMENT

The participants were classified by blood lead concentration into the low-level (≤2.189 µg/dL, n=5756) and high-level (>2.189 µg/dL, n=5754) groups. The main outcome, stroke, was assessed by information from physician diagnosis, prevalence of stroke or treatment for stroke. The ORs and 95% CIs were calculated to evaluate the association between blood lead level and stroke using multivariate logistic regression analysis.

RESULTS

Although blood lead level was not significantly associated with stroke (OR: 1.30, 95% CI: 0.66-2.58) in the multivariate-adjusted model, in individuals with hypertension, the high-level group was 2.36-fold higher odds of stroke (OR: 2.36, 95% CI: 1.02-5.44) compared to that in the low-level group. No association was observed in individuals with normotension (OR: 0.42, 95% CI: 0.13-1.38, p for interaction=0.007).

CONCLUSION

The association between blood lead concentration and stroke may be influenced by hypertension status. Our findings suggest the need for closer attention to lead exposure in patients with hypertension.

Altered COVID-19 receptor ACE2 expression in a higher risk group for cerebrovascular disease and ischemic stroke

Coronavirus disease 2019 (COVID-19) is a worldwide pandemic. It has a high transmission rate among humans, and is a threat to global public health. However, there are no effective prophylactics or therapeutics available. It is necessary to identify vulnerable and susceptible groups for adequate protection and care against this disease. Recent studies have reported that COVID-19 has angiotensin-converting enzyme 2 (ACE2) as a functional receptor, which may lead to the development of severe cerebrovascular diseases (CVD), including strokes, in patients with risk factors for CVD such as diabetes and smoking. Thus, the World Health Organization (WHO) advised caution against COVID-19 for smokers and patients with underlying clinical symptoms, including cardiovascular diseases. Here, we observed ACE2 expression in the brain of rat middle cerebral artery occlusion (MCAO) model and evaluated the effects of cigarette smoke extract (CSE) and diabetes on ACE2 expression in vessels. We showed that the levels of ACE2 expression was increased in the cortex penumbra after ischemic injuries. CSE treatment significantly elevated ACE2 expression in human brain vessels. We found that ACE2 expression was upregulated in primary cultured human blood vessels with diabetes compared to healthy controls. This study demonstrates that ACE2 expression is increased in ischemic brains and vessels exposed to diabetes or smoking, makes them vulnerable to COVID-19 infection.

Altered expression of Notch1 in Alzheimer's disease

Notch signaling is an evolutionarily conserved pathway that regulates cell-cell interactions through binding of Notch family receptors to their cognate ligands. Notch signaling has an essential role in vascular development and angiogenesis. Recent studies have reported that Notch may be implicated in Alzheimer’s disease (AD) pathophysiology. We measured the levels of soluble Notch1 (sNotch1) in the plasma samples from 72 dementia patients (average age 75.1 y), 89 subjects with amnestic mild cognitive impairment (MCI) (average age 73.72 y), and 150 cognitively normal controls (average age 72.34 y). Plasma levels of sNotch1 were 25.27% lower in dementia patients as compared to healthy control subjects. However, the level of Notch1 protein was significantly increased in human brain microvascular endothelial cells (HBMECs) after amyloid-beta treatment. Also, Notch1 mRNA level was significantly increased in HBMECs and iPSC-derived neuronal cells from AD patient compared to normal control. These results indicate that altered expression of Notch1 might be associated with the risk of Alzheimer’s disease.

Involvement of ADAM10 in acrolein-induced astrocytic inflammation

Acrolein is a neurotoxin produced through lipid peroxidation in the brain affected by ischemic stroke, which results in neuronal cell injury and inflammation. However the mechanism underlying acrolein-induced brain inflammation remains unclear. Therefore we examined how acrolein leads to astrocytic inflammation. It was found that acrolein increased the levels of NLRP3 and cleaved caspase-1, which led to the maturation of interleukin-1β (IL-1β). ELISA assay results, which showed that acrolein increased the secreted IL-1β, further supported acrolein-induced astrocytic inflammation. Acrolein increased ADAM10 protein levels and the cleavage of N-cadherin. The ADAM10 inhibitor, GI 254023X blocked N-cadherin cleavage by acrolein, suggesting that ADAM10 is an upstream of N-cadherin. Furthermore, we found that acrolein activated p38 MAPK and NF-κB p65, while pretreatment with p38 MAPK inhibitor, SB203580 and GI 254023X inhibited NF-κB p65 activation and NLRP3 inflammasome. This suggests that p38 MAPK mediates the activation of NF-κB p65, which is associated with NLRP3 expression. Finally, we showed that acrolein induced cell toxicity and decrease of EAAT1 expression, suggesting that acrolein may induce a loss of glutamate uptake function. In conclusion, we demonstrate that acrolein induces astrocytic inflammation through NLRP3 inflammasome, which is regulated by ADAM10 and attributed to p38 MAPK-activated NF-κB p65 activity.

Plasma ATG5 is increased in Alzheimer's disease

Alzheimer’s disease (AD) is a major cause of dementia. Growing evidence suggests that dysregulation of autophagy, a cellular mechanism essential for self-digestion of damaged proteins and organelles, is involved in neurological degenerative diseases including AD. Previously, we reported that autophagosomes are increased in the brains of AD mouse model. However, the plasma levels of autophagic markers have not yet been investigated in patients with AD. In this study, we investigated the expression of autophagy-related genes 5 and 12 (ATG5 and ATG12, respectively) in cells in vitro upon amyloid-beta (Aβ) treatment and in the plasma of AD patients. ATG5-ATG12 complex levels were increased in primary rat cortical neurons and human umbilical vein endothelial cells after Aβ treatment. Furthermore, we compared plasma from 69 patients with dementia, 82 patients with mild cognitive impairment (MCI), and 127 cognitively normal control participants. Plasma levels of ATG5 were significantly elevated in patients with dementia (149.3 ± 7.5 ng/mL) or MCI (152.9 ± 6.9 ng/mL) compared with the control subjects (129.0 ± 4.1 ng/mL) (p = 0.034, p = 0.016, respectively). Our results indicate that alterations in the plasma ATG5 levels might be a potential biomarker in patients at risk for AD.

Cigarette smoke extracts and cadmium induce COX-2 expression through γ-secretase-mediated p38 MAPK activation in C6 astroglia cells

Exposure to cigarette smoke has been implicated in the progression of cerebrovascular and neurological disorders like stroke through inflammation and blood-brain barrier disruption. In this study, we investigated the signaling cascade activated by cigarette smoke extracts (CSE) and cadmium (Cd) resulting in the COX-2 induction in C6 rat astroglia cells. CSE or Cd induced Notch1 cleavage and activated p38 MAPK and CREB signaling pathways in C6 astroglia cells. Knockdown of nicastrin using siRNA or γ-secretase inhibitors, DAPT and L-685,486, reduced Notch1 cleavage and phosphorylation of p38 MAPK and CREB, while phosphorylation of ERK and JNK remained unaffected. Additionally, the blockage of γ-secretase activity did not show any effect on the phosphorylation of AKT, another upstream activator of CREB, indicating that γ-secretase-mediated CREB activation occurs via p38 MAPK. γ-secretase inhibitor also inhibited the CSE and Cd-mediated increase in the expression of COX-2. Furthermore, recombinant overexpression of Notch1 intracellular domain resulted in an increase in the expression of COX-2. Notch signaling induced by CSE and Cd induced apoptosis in C6 cells. Our results demonstrate that CSE exposure activated the p38 MAPK and CREB-mediated induction in COX-2 expression in astrocytes via γ-secretase-mediated Notch1 signaling. Our data provides novel insights into the potential mechanism of pro-inflammatory response activated by exposure to cigarette smoke.

A Major Locus for Quantitatively Measured Shank Skin Color Traits in Korean Native Chicken

Shank skin color of Korean native chicken (KNC) shows large color variations. It varies from white, yellow, green, bluish or grey to black, whilst in the majority of European breeds the shanks are typically yellow-colored. Three shank skin color-related traits (i.e., lightness [L*], redness [a*], and yellowness [b*]) were measured by a spectrophotometer in 585 progeny from 68 nuclear families in the KNC resource population. We performed genome scan linkage analysis to identify loci that affect quantitatively measured shank skin color traits in KNC. All these birds were genotyped with 167 DNA markers located throughout the 26 autosomes. The SOLAR program was used to conduct multipoint variance-component quantitative trait locus (QTL) analyses. We detected a major QTL that affects b* value (logarithm of odds [LOD] = 47.5, p = 1.60×10⁻⁴⁹) on GGA24 (GGA for Gallus gallus). At the same location, we also detected a QTL that influences a* value (LOD = 14.2, p = 6.14×10⁻¹⁶). Additionally, beta-carotene dioxygenase 2 (BCDO2), the obvious positional candidate gene under the linkage peaks on GGA24, was investigated by the two association tests: i.e., measured genotype association (MGA) and quantitative transmission disequilibrium test (QTDT). Significant associations were detected between BCDO2 g.9367 A>C and a* (P_MGA = 1.69×10⁻²⁸; P_QTDT = 2.40×10⁻²⁵). The strongest associations were between BCDO2 g.9367 A>C and b* (P_MGA = 3.56×10⁻⁶⁶; P_QTDT = 1.68×10⁻⁶⁵). However, linkage analyses conditional on the single nucleotide polymorphism indicated that other functional variants should exist. Taken together, we demonstrate for the first time the linkage and association between the BCDO2 locus on GGA24 and quantitatively measured shank skin color traits in KNC.

Fisetin stimulates autophagic degradation of phosphorylated tau via the activation of TFEB and Nrf2 transcription factors

The neuronal accumulation of phosphorylated tau plays a critical role in the pathogenesis of Alzheimer's disease (AD). Here, we examined the effect of fisetin, a flavonol, on tau levels. Treatment of cortical cells or primary neurons with fisetin resulted in significant decreases in the levels of phosphorylated tau. In addition, fisetin decreased the levels of sarkosyl-insoluble tau in an active GSK-3β-induced tau aggregation model. However, there was no difference in activities of tau kinases and phosphatases such as protein phosphatase 2A, irrespective of fisetin treatment. Fisetin activated autophagy together with the activation of transcription factor EB (TFEB) and Nrf2 transcriptional factors. The activation of autophagy including TFEB is likely due to fisetin-mediated mammalian target of rapamycin complex 1 (mTORC1) inhibition, since the phosphorylation levels of p70S6 kinase and 4E-BP1 were decreased in the presence of fisetin. Indeed, fisetin-induced phosphorylated tau degradation was attenuated by chemical inhibitors of the autophagy-lysosome pathway. Together the results indicate that fisetin reduces levels of phosphorylated tau through the autophagy pathway activated by TFEB and Nrf2. Our result suggests fisetin should be evaluated further as a potential preventive and therapeutic drug candidate for AD.

SUMO1 promotes Aβ production via the modulation of autophagy

Autophagy is one of the main mechanisms in the pathophysiology of neurodegenerative disease. The accumulation of autophagic vacuoles (AVs) in affected neurons is responsible for amyloid-β (Aβ) production. Previously, we reported that SUMO1 (small ubiquitin-like modifier 1) increases Aβ levels. In this study, we explored the mechanisms underlying this. We investigated whether AV formation is necessary for Aβ production by SUMO1. Overexpression of SUMO1 increased autophagic activation, inducing the formation of LC3-II-positive AVs in neuroglioma H4 cells. Consistently, autophagic activation was decreased by the depletion of SUMO1 with small hairpin RNA (shRNA) in H4 cells. The SUMO1-mediated increase in Aβ was reduced by the autophagy inhibitors (3-methyladenine or wortmannin) or genetic inhibitors (siRNA targeting ATG5, ATG7, ATG12, or HIF1A), respectively. Accumulation of SUMO1, ATG12, and LC3 was seen in amyloid precursor protein transgenic mice. Our results suggest that SUMO1 accelerates the accumulation of AVs and promotes Aβ production, which is a key mechanism for understanding the AV-mediated pathophysiology of Alzheimer disease.

Enzymatic hydrolysis of ovomucoid and the functional properties of its hydrolysates

Ovomucoid is well known as a "trypsin inhibitor" and is considered to be the main food allergen in egg. However, the negative functions of ovomucoid can be eliminated if the protein is cut into small peptides. The objectives of this study were to hydrolyze ovomucoid using various enzyme combinations, and compare the functional properties of the hydrolysates. Purified ovomucoid was dissolved in distilled water (20 mg/mL) and treated with 1% of pepsin, α-chymotrypsin, papain, and alcalase, singly or in combinations. Sodium sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) results of the hydrolysates indicated that pepsin (OMP), alcalase (OMAl), alcalase+trypsin (OMAlTr), and alcalase+papain (OMAlPa) treatments best hydrolyzed the ovomucoid, and the 4 treatments were selected to determine their functional characteristics. Among the 4 enzyme treatments, hydrolysate from OMAlTr showed the highest iron-chelating and antioxidant activities, while OMP showed higher ACE-inhibitory activity, but lower Fe-chelating activity than the other treatments. However, no difference in the copper-chelating activity among the treatments was found. MS/MS analysis identified numerous peptides from the hydrolysates of OMAlPa and OMAlTr, and majority of the peptides produced were <2 kDa. Pepsin treatment (OMP), however, hydrolyzed ovomucoid almost completely and produced only amino acid monomers, di- and tri-peptides. The ACE-inhibitory, antioxidant and iron-chelating activities of the enzyme hydrolysates were not consistent with the number and size of peptides in the hydrolysates, but we do not have information about the quantity of each peptide present in the hydrolysates at this point.

NDP52 associates with phosphorylated tau in brains of an Alzheimer disease mouse model

We previously showed that NDP52 (also known as calcoco2) plays a role as an autophagic receptor for phosphorylated tau facilitating its clearance via autophagy. Here, we examined the expression and association of NDP52 with autophagy-regulated gene (ATG) proteins including LC3, as well as phosphorylated tau and amyloid-beta (Aβ) in brains of an AD mouse model. NDP52 was expressed not only in neurons, but also in microglia and astrocytes. NDP52 co-localized with ATGs and phosphorylated tau as expected since it functions as an autophagy receptor for phosphorylated tau in brain. Compared to wild-type mice, the number of autophagic vesicles (AVs) containing NDP52 in both cortex and hippocampal regions was significantly greater in AD model mice. Moreover, the protein levels of NDP52 and phosphorylated tau together with LC3-II were also significantly increased in AD model mice, reflecting autophagy impairment in the AD mouse model. By contrast, a significant change in p62/SQSTM1 level was not observed in this AD mouse model. NDP52 was also associated with intracellular Aβ, but not with the extracellular Aβ of amyloid plaques. We conclude that NDP52 is a key autophagy receptor for phosphorylated tau in brain. Further our data provide clear evidence for autophagy impairment in brains of AD mouse model, and thus strategies that result in enhancement of autophagic flux in AD are likely to be beneficial.

A whole genome association study on meat palatability in hanwoo

A whole genome association (WGA) study was carried out to find quantitative trait loci (QTL) for sensory evaluation traits in Hanwoo. Carcass samples of 250 Hanwoo steers were collected from National Agricultural Cooperative Livestock Research Institute, Ansung, Gyeonggi province, Korea, between 2011 and 2012 and genotyped with the Affymetrix Bovine Axiom Array 640K single nucleotide polymorphism (SNP) chip. Among the SNPs in the chip, a total of 322,160 SNPs were chosen after quality control tests. After adjusting for the effects of age, slaughter-year-season, and polygenic effects using genome relationship matrix, the corrected phenotypes for the sensory evaluation measurements were regressed on each SNP using a simple linear regression additive based model. A total of 1,631 SNPs were detected for color, aroma, tenderness, juiciness and palatability at 0.1% comparison-wise level. Among the significant SNPs, the best set of 52 SNP markers were chosen using a forward regression procedure at 0.05 level, among which the sets of 8, 14, 11, 10, and 9 SNPs were determined for the respectively sensory evaluation traits. The sets of significant SNPs explained 18% to 31% of phenotypic variance. Three SNPs were pleiotropic, i.e. AX-26703353 and AX-26742891 that were located at 101 and 110 Mb of BTA6, respectively, influencing tenderness, juiciness and palatability, while AX-18624743 at 3 Mb of BTA10 affected tenderness and palatability. Our results suggest that some QTL for sensory measures are segregating in a Hanwoo steer population. Additional WGA studies on fatty acid and nutritional components as well as the sensory panels are in process to characterize genetic architecture of meat quality and palatability in Hanwoo.

Phylogenetic Analysis of a Privately-owned Korean Native Chicken Population Using mtDNA D-loop Variations

The use of Korean native chicken is increasing, and the discovery of new genetic resources is very important from both economic and genetic conservation points of view. In this study, mtDNA D-loop sequences from 272 privately-owned Korean native chickens from a Hyunin farm were investigated. Seventeen nucleotide substitutions were identified from the sequence analysis and they were classified as 6 haplotypes. Previously investigated haplotypes in five Korean native chicken populations have been compared with the Hyunin chicken population. The results indicated that two haplotypes, H10 and H15, in the Hyunin chicken population were not previously identified in other Korean native chicken populations, representing 33.09% (90/272) and 1.1% (3/272) of the Hyunin population, respectively. On the other hand, four other haplotypes were identical to those of a previous study of Korean native chicken populations. This result is indicative of conservation strategies of Hyunin chicken populations for expanding the genetic diversity in the Korean native chicken population.

Discrimination of korean native chicken lines using fifteen selected microsatellite markers

In order to evaluate the genetic diversity and discrimination among five Korean native chicken lines, a total of 86 individuals were genotyped using 150 microsatellite (MS) markers, and 15 highly polymorphic MS markers were selected. Based on the highest value of the number of alleles, the expected heterozygosity (He) and polymorphic information content (PIC) for the selected markers ranged from 6 to 12, 0.466 to 0.852, 0.709 to 0.882 and 0.648 to 0.865, respectively. Using these markers, the calculated genetic distance (Fst), the heterozygote deficit among chicken lines (Fit) and the heterozygote deficit within chicken line (Fis) values ranged from 0.0309 to 0.2473, 0.0013 to 0.4513 and -0.1002 to 0.271, respectively. The expected probability of identity values in random individuals (PI), random half-sib (PI half-sibs ) and random sibs (PI sibs ) were estimated at 7.98×10(-29), 2.88×10(-20) and 1.25×10(-08), respectively, indicating that these markers can be used for traceability systems in Korean native chickens. The unrooted phylogenetic neighbor-joining (NJ) tree was constructed using 15 MS markers that clearly differentiated among the five native chicken lines. Also, the structure was estimated by the individual clustering with the K value of 5. The selected 15 MS markers were found to be useful for the conservation, breeding plan, and traceability system in Korean native chickens.

Investigation of MC1R SNPs and Their Relationships with Plumage Colors in Korean Native Chicken

The melanocortin 1 receptor (MC1R) gene is related to the plumage color variations in chicken. Initially, the MC1R gene from 30 individuals was sequenced and nine polymorphisms were obtained. Of these, three and six single nucleotide polymorphisms (SNPs) were confirmed as synonymous and nonsynonymous mutations, respectively. Among these, three selected SNPs were genotyped using the restriction fragment length polymorphism (RFLP) method in 150 individuals from five chicken breeds, which identified the plumage color responding alleles. The neighbor-joining phylogenetic tree using MC1R gene sequences indicated three well-differentiated different plumage pigmentations (eumelanin, pheomelanin and albino). Also, the genotype analyses indicated that the TT, AA and GG genotypes corresponded to the eumelanin, pheomelanin and albino plumage pigmentations at nucleotide positions 69, 376 and 427, respectively. In contrast, high allele frequencies with T, A and G alleles corresponded to black, red/yellow and white plumage color in 69, 376 and 427 nucleotide positions, respectively. Also, amino acids changes at position Asn23Asn, Val126Ile and Thr143Ala were observed in melanin synthesis with identified possible alleles, respectively. In addition, high haplotype frequencies in TGA, CGG and CAA haplotypes were well discriminated based on the plumage pigmentation in chicken breeds. The results obtained in this study can be used for designing proper breeding and conservation strategies for the Korean native chicken breeds, as well as for the developing breed identification markers in chicken.

Sulforaphane induces autophagy through ERK activation in neuronal cells

Sulforaphane (SFN), an activator of nuclear factor E2-related factor 2 (Nrf2), has been reported to induce autophagy in several cells. However, little is known about its signaling mechanism of autophagic induction. Here, we provide evidence that SFN induces autophagy with increased levels of LC3-II through extracellular signal-regulated kinase (ERK) activation in neuronal cells. Pretreatment with NAC (N-acetyl-l-cysteine), a well-known antioxidant, completely blocked the SFN-induced increase in LC3-II levels and activation of ERK. Knockdown or overexpression of Nrf2 did not affect autophagy. Together, the results suggest that SFN-mediated generation of reactive oxygen species (ROS) induces autophagy via ERK activation, independent of Nrf2 activity in neuronal cells.

Nrf2 reduces levels of phosphorylated tau protein by inducing autophagy adaptor protein NDP52

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a pivotal transcription factor in the defence against oxidative stress. Here we provide evidence that activation of the Nrf2 pathway reduces the levels of phosphorylated tau by induction of an autophagy adaptor protein NDP52 (also known as CALCOCO2) in neurons. The expression of NDP52, which we show has three antioxidant response elements (AREs) in its promoter region, is strongly induced by Nrf2, and its overexpression facilitates clearance of phosphorylated tau in the presence of an autophagy stimulator. In Nrf2-knockout mice, phosphorylated and sarkosyl-insoluble tau accumulates in the brains concurrent with decreased levels of NDP52. Moreover, NDP52 associates with phosphorylated tau from brain cortical samples of Alzheimer disease cases, and the amount of phosphorylated tau in sarkosyl-insoluble fractions is inversely proportional to that of NDP52. These results suggest that NDP52 plays a key role in autophagy-mediated degradation of phosphorylated tau in vivo.

Cadmium induces N-cadherin cleavage via ERK-mediated γ-secretase activation in C6 astroglia cells

N-cadherin has known to be involved in tumor progression and metastasis. However, it is still obscure about the signaling pathway involving in the processing of N-cadherin. Thus, we examined which signaling pathway plays a major role in the processing of N-cadherin in C6 glioma cells following treatment of cadmium (Cd), a highly ubiquitous heavy metal. A cleavage product of N-cadherin, N-cad/CTF2 was observed by the treatment of Cd to C6 cells in a time and concentration-dependent manner. The production of N-cad/CTF2 was inhibited by pretreatment of γ-secretase inhibitors or siRNA transfection of nicastrin, indicating that γ-secretase is involved in the cleavage. Interestingly, Cd could activate both ERK and JNK signaling pathways in C6 cells; however, γ-secretase-mediated N-cad/CTF2 production by Cd was completely blocked by MEK1/2 inhibitors PD184352 and U0126, but not by a JNK inhibitor SP600125, demonstrating that the ERK signaling pathway plays a major role in the cleavage. In addition, pretreatment of an antioxidant or Ca²⁺ blocker blocked the production of N-cad/CTF2 by Cd together with the inhibition of ERK1/2 phosphorylation. Collectively, these results suggest that Cd increases intracellular Ca²⁺ or ROS, which induces γ-secretase-dependent N-cad/CTF2 production via the activation of the ERK signaling pathway in C6 glial cells.

Impaired mitochondrial dynamics and Nrf2 signaling contribute to compromised responses to oxidative stress in striatal cells expressing full-length mutant huntingtin

Huntington disease (HD) is an inherited neurodegenerative disease resulting from an abnormal expansion of polyglutamine in huntingtin (Htt). Compromised oxidative stress defense systems have emerged as a contributing factor to the pathogenesis of HD. Indeed activation of the Nrf2 pathway, which plays a prominent role in mediating antioxidant responses, has been considered as a therapeutic strategy for the treatment of HD. Given the fact that there is an interrelationship between impairments in mitochondrial dynamics and increased oxidative stress, in this present study we examined the effect of mutant Htt (mHtt) on these two parameters. STHdh(Q111/Q111) cells, striatal cells expressing mHtt, display more fragmented mitochondria compared to STHdh(Q7/Q7) cells, striatal cells expressing wild type Htt, concurrent with alterations in the expression levels of Drp1 and Opa1, key regulators of mitochondrial fission and fusion, respectively. Studies of mitochondrial dynamics using cell fusion and mitochondrial targeted photo-switchable Dendra revealed that mitochondrial fusion is significantly decreased in STHdh(Q111/Q111) cells. Oxidative stress leads to dramatic increases in the number of STHdh(Q111/Q111) cells containing swollen mitochondria, while STHdh(Q7/Q7) cells just show increases in the number of fragmented mitochondria. mHtt expression results in reduced activity of Nrf2, and activation of the Nrf2 pathway by the oxidant tBHQ is significantly impaired in STHdh(Q111/Q111) cells. Nrf2 expression does not differ between the two cell types, but STHdh(Q111/Q111) cells show reduced expression of Keap1 and p62, key modulators of Nrf2 signaling. In addition, STHdh(Q111/Q111) cells exhibit increases in autophagy, whereas the basal level of autophagy activation is low in STHdh(Q7/Q7) cells. These results suggest that mHtt disrupts Nrf2 signaling which contributes to impaired mitochondrial dynamics and may enhance susceptibility to oxidative stress in STHdh(Q111/Q111) cells.

Analysis of volatile components and the sensory characteristics of irradiated raw pork

Longissimus dorsi muscle strips, approximately 20 mm long, 40 mm wide, and 5 mm thick (4 g), of pig were randomly placed in a single layer into labeled bags (four strips per bag) and packaged either aerobically or under vacuum. Samples in the bags were irradiated at 0, 5, or 10 kGy and stored at 4°C for 5 days. Lipid oxidation, the amount and identity of volatile components and sensory characteristics of raw pork strips were determined at 0 and 5 days of storage. Irradiated muscle strips produced more 2-thiobarbituric acid reactive substances (TBARS) than nonirradiated only in aerobic packaging during storage. Irradiation had no effect on the production of volatiles related to lipid oxidation, but produced a few sulfur-containing compounds not found in nonirradiated meat. This indicates that the major contributor of off-odor in irradiated meat is not lipid oxidation, but radiolytic breakdown of sulfur-containing amino acids. Many of the irradiation-dependent volatiles reduced to 50 to 25% levels during the 5-days storage under aerobic conditions. Irradiated muscle strips produced stronger irradiation odor than nonirradiated, but no irradiation dose or storage effect was found. Irradiation had no negative effect on the acceptance of meat, and approximately 70% of sensory panels characterized irradiation odor as barbecued-corn-like odor.

Effect of irradiation and packaging conditions after cooking on the formation of cholesterol and lipid oxidation products in meats during storage

The effect of irradiation and packaging conditions on the content of cholesterol oxidation products (COPs) and lipid oxidation in cooked turkey, beef, and pork during storage was studied. Ground turkey leg, beef, and pork were cooked, packaged either in oxygen-permeable or oxygen-impermeable bags, and irradiated at 0 or 4.5 kGy. Lipid oxidation and COPs were determined after 0 and 7 days of storage at 4°C. Packaging of cooked meat was more important than irradiation in developing COPs and lipid oxidation in cooked meats during storage. 7α-Hydroxycholesterol, 7β-hydroxycholesterol, β-epoxide, and 7-ketocholesterol were among the major COPs formed in cooked turkey, beef, and pork after storage, and their amounts increased dramatically during the 7-day storage in aerobic conditions. Irradiation had no significant effect on the amounts of any of the COPs found in cooked turkey and beef, but increased (P<0.05) the amounts of α- plus 7β-hydroxycholesterol, β-epoxide, 7-ketocholesterol, and total COPs in aerobically packaged cooked pork. The amounts of COPs and lipid oxidation products (TBARS) closely related to the proportion of polyunsaturated fatty acids in meat. The results indicated that the composition of fats in meat is important on the oxidation rates of lipids and cholesterol, and packaging is far more important than irradiation in the formation of COPs and lipid oxidation in cooked meat.

Effect of muscle type, packaging, and irradiation on lipid oxidation, volatile production, and color in raw pork patties

Effects of packaging and irradiation combinations on lipid oxidation, off-flavor, and color changes of raw patties prepared from three pork muscles were studied. Patties were prepared from each of the ground L. dorsi (L. thoracis and lumborum), psoas, and R. femoris muscles of pig, packaged either in oxygen permeable polyethylene bags or impermeable nylon/polyethylene bags, irradiated with an electron beam at 0 or 4.5 kGy dose, and then stored up to two weeks at 4 °C. Lipid 8 oxidation and color of the patties were determined after 0, 3, 7, and 14 days of storage, and volatiles 24 hr after irradiation. Irradiation and high fat content accelerated the lipid oxidation in raw meat during storage. Oxygen availability during storage, however, was more important than irradiation on the lipid oxidation and color values of raw patties. Irradiated meat produced more volatiles than nonirradiated patties, and the proportion of volatiles varied by the packaging-irradiation conditions of patties. Irradiation produced many unidentified volatiles that could be responsible for the off-odor in irradiated raw meat. No single volatile components but total volatiles, however, could be used to predict lipid oxidation status of raw meat.

SUMO1 modulates Aβ generation via BACE1 accumulation

Accumulation of disease-related proteins is a characteristic event observed in the pathogenesis of neurodegenerative diseases. β-secretase (BACE)-1, which initiates generation of β-amyloid (Aβ), is increased in the Alzheimer's diseased brain. However, the mechanisms of BACE1 accumulation in Alzheimer's disease are largely unknown. In this report, we found that small ubiquitin-like modifier (SUMO)-1 interacts with the dileucine motif of BACE1 and regulates the level of BACE1 protein. This was proved by the coimmunoprecipitation, and gain or loss of function experiments. Altering 3 SUMO isoforms affects BACE1 protein levels, and consequently results in altered amyloid precursor protein processing and Aβ generation. BACE1 levels were increased in response to Aβ or apoptosis, but not in cells lacking SUMO1. Aβ increased SUMO1 protein levels in rat cortical neurons. Moreover, SUMO1 immunoreactivity was increased in the amyloid precursor protein transgenic mice. Furthermore, the C-terminus fragments of BACE1 containing dileucine motif reduced Aβ generation by SUMO1 overexpression. Our study indicates SUMO1 is not only a novel and potent regulator of BACE1 accumulation and Aβ generation but also a potential therapeutic target for Alzheimer's disease.

Effect of sex and dietary organic zinc on growth performance, carcass traits, tissue mineral content, and blood parameters of broiler chickens

Zinc (Zn) is an essential mineral for animal development and function. A study was carried out to evaluate the effect of sex and dietary organic zinc (OZ) on growth performance, carcass traits, tissue mineral content, and blood parameters of broiler chickens. A total of 240 1-day-old male and 240 female broiler chicks (Cobb × Cobb) were assigned to two dietary levels of OZ (2 × 2 factorial) with six replicates per treatment (20 birds/replicate pen). The OZ supplementation levels were 0 and 25 ppm. Results showed that OZ supplementation did not affect the growth performance of male and female broilers, but the males showed significantly better (P < 0.05) growth performance than females did. Similarly, OZ supplementation did not affect the thickness of both the back and thigh skin of male and female broilers; however, males had thicker skin than females. Dietary OZ supplementation did not affect collagen contents in the skin and meat samples. Male broilers had higher skin collagen contents than females, but no sex difference was found in meat collagen contents. OZ supplementation did not affect the shear force values of skin and meat samples. Male broilers had higher shear force values of back skin than females, but not in the meat samples. Dietary OZ supplementation increased (P < 0.05) the thigh meat Zn content in both sexes. The plasma Ca content was significantly (P < 0.05) increased by dietary OZ supplementation; however, other blood parameters were not affected by dietary OZ supplementation. Males had higher plasma glucose and cholesterol content than females. It is concluded that dietary OZ supplementation at the level of 25 ppm does not affect the growth performance and skin quality of broiler chickens but increases the Zn content in thigh meat and Ca content in plasma of broiler chickens. Male broilers had better growth performance and skin quality than females.

γ-Secretase-dependent cleavage of E-cadherin by staurosporine in breast cancer cells

E-cadherin is a transmembrane protein that serves as a cell adhesion molecule component of the adherens junction. We previously showed that cadmium induced γ-secretase-dependent E-cadherin cleavage via oxidative stress. In this study, we report that staurosporine (STS)-induced apoptosis induces caspase-2 and/or -8-dependent E-cadherin cleavage. STS increased γ-secretase-dependent cleavage of E-cadherin in breast cancer cells through caspase activation. The ability of the γ-secretase inhibitor DAPT and the caspase inhibitor zVAD-FMK to block E-cadherin cleavage provided support for these results. The cleavage of E-cadherin was blocked by caspase-2 and -8 inhibitors. Immunofluorescence analysis confirmed that, along with the disappearance of E-cadherin staining at the cell surface, the E-cadherin cytoplasmic domain accumulated in the cytosol. In the presence of an inhibitor of γ-secretase or caspase, the cleavage of E-cadherin was partially blocked. Our findings suggest that activation of caspase-2/-8 stimulated the disruption of cadherin-mediated cell-cell contacts in apoptotic cells via γ-secretase activation.

Supplementation of graded levels of organic zinc in the diets of female broilers: effects on performance and carcase quality

Zinc is an essential trace element. The objective of this research was to investigate the effects of various levels of organic zinc (OZ) supplementation on growth performance and carcase quality of female broiler chickens. A total of 3200 1-d-old female broiler chicks were randomly allotted to 16 floor pens with 200 birds per pen. A maize-wheat-soyabean meal basal diet (Control) was formulated and 20 mg/kg OZ (20 OZ), 40 mg/kg OZ (40 OZ), and 80 mg/kg OZ (80 OZ) were added to the basal diet to form 4 dietary treatments with 4 replicates per treatment. The OZ source was zinc proteinate which contained 15% zinc. Results showed no significant difference between the treatments in growth performance. A significant increase in thigh skin epidermis and dermis thickness was shown in the OZ supplementation groups; however, no effect was found on the thickness of back skin epidermis and dermis. Collagen contents in breast and thigh meats were not influenced by OZ supplementation but a significant increase in collagen content was found in the back and thigh skin. This increase in collagen content was significantly greater in the back and thigh skin of OZ 80 than with OZ 20. Shear force value and zinc concentration in skins and meat were not significantly influenced by supplementation with OZ. It is concluded that dietary OZ does not improve growth performance of broilers; however, it could increase skin thickness by increasing collagen content in skin, thereby improving carcase quality.