Revealing potential Rab proteins participate in regulation of secretory autophagy machinery.

Autophagy can be classified as degradative and secretory based on distinct functions. The small GTPase proteins Rab8a and Rab37 are responsible for secretory autophagy-mediated exocytosis of IL-1ß, insulin, and TIMP1 (tissue inhibitor of 54 metalloproteinase 1). Other Rab family members participating in secretory autophagy are poorly understood. Herein, we identified 26 overlapped Rab proteins in purified autophagosomes of mouse pancreatic ß-cell "Min-6" and human lung cancer cell "CL1-5-Q89L" with high secretory autophagy tendency by LC-MS/MS proteomics analysis. Six Rab proteins (Rab8a, Rab11b, Rab27a, Rab35, Rab37, and Rab7a) were detected in autophagosomes of four cell lines, associating them with autophagy-related vesicle trafficking. We used CL1-5-Q89L cell line model to evaluate the levels of Rab proteins colocalization with autophagy LC3 proteins and presence in purified autophagosomes. We found five Rab proteins (Rab8a, Rab11b, Rab27a, Rab35, and Rab37) are highly expressed in the autophagosome compared to the normal control by immunoblotting under active secretion conditions. However, only Rab8a, Rab35, and Rab37 showing high colocalization with LC3 protein by cofocal microscopy. Despite the discrepancy between the image and immunoblotting analysis, our data sustains the speculation that Rab8a, Rab11b, Rab27a, Rab35, and Rab37 are possibly associated with the secretory autophagy machinery. In contrast, Rab7a shows low colocalization with LC3 puncta and low level in the autophagosome, suggesting it regulates different vesicle trafficking machineries. Our findings open a new direction toward exploring the role of Rab proteins in secretory autophagy-related cargo exocytosis and identifying the cargoes and effectors regulated by specific Rab proteins.

Critical roles of tubular mitochondrial ATP synthase dysfunction in maleic acid-induced acute kidney injury.

Maleic acid (MA) induces renal tubular cell dysfunction directed to acute kidney injury (AKI). AKI is an increasing global health burden due to its association with mortality and morbidity. However, targeted therapy for AKI is lacking. Previously, we determined mitochondrial-associated proteins are MA-induced AKI affinity proteins. We hypothesized that mitochondrial dysfunction in tubular epithelial cells plays a critical role in AKI. In vivo and in vitro systems have been used to test this hypothesis. For the in vivo model, C57BL/6 mice were intraperitoneally injected with 400 mg/kg body weight MA. For the in vitro model, HK-2 human proximal tubular epithelial cells were treated with 2 mM or 5 mM MA for 24 h. AKI can be induced by administration of MA. In the mice injected with MA, the levels of blood urea nitrogen (BUN) and creatinine in the sera were significantly increased (p < 0.005). From the pathological analysis, MA-induced AKI aggravated renal tubular injuries, increased kidney injury molecule-1 (KIM-1) expression and caused renal tubular cell apoptosis. At the cellular level, mitochondrial dysfunction was found with increasing mitochondrial reactive oxygen species (ROS) (p < 0.001), uncoupled mitochondrial respiration with decreasing electron transfer system activity (p < 0.001), and decreasing ATP production (p < 0.05). Under transmission electron microscope (TEM) examination, the cristae formation of mitochondria was defective in MA-induced AKI. To unveil the potential target in mitochondria, gene expression analysis revealed a significantly lower level of ATPase6 (p < 0.001). Renal mitochondrial protein levels of ATP subunits 5A1 and 5C1 (p < 0.05) were significantly decreased, as confirmed by protein analysis. Our study demonstrated that dysfunction of mitochondria resulting from altered expression of ATP synthase in renal tubular cells is associated with MA-induced AKI. This finding provides a potential novel target to develop new strategies for better prevention and treatment of MA-induced AKI.

High-Frequency Fluctuation Intensity as a Predictor of Post-Stenotic Dilatation in Swine.

OBJECTIVE: To identify the turbulent components of blood flow facilitating aortic lumen dilatation in a post-stenotic dilatation (PSD) porcine model. METHODS: The porcine abdominal aorta (AA) was moderately coarctated to induce overt flow turbulence in the downstream region and to lead to dilatation in time periods between four and twelve weeks. We propose a new metric, fluctuation intensity (FI), to quantify turbulent fluctuations of pulsatile aortic flow measured within twenty minutes post-coarctation. Lumen perimeter ratio (LPR) of the distal-to-suprarenal AA was used to assess the degree of PSD. Using k-means clustering analysis, we first divided FI frequency spectrum into low- and high-frequency fluctuation intensity (LFFI and HFFI), and subsequently grouped animals with coarctation. Receiver operating characteristic (ROC) analysis was performed to evaluate the ability of the proposed metric to predict PSD. RESULTS: The frequency band of the FI spectrum in facilitating aortic lumen dilatation was identified to be 40∼200 Hz. Using sham group as the reference, pigs receiving coarctation were clustered into two groups with (group A) and without (group B) increases in HFFI values. Coarctation significantly increased LPR values in group A, but not in group B. Moreover, group A exhibited a high probability density distribution on severe elastic fiber fragmentation. ROC analysis indicated HFFI to be capable of predicting PSD with excellent sensitivity and specificity. CONCLUSION: High-intensity, high-frequency components of blood flow fluctuations induced by moderate coarctation promote elastic lamella degradation and aortic lumen dilatation. SIGNIFICANCE: HFFI application in flowmeter programs may provide a useful predictor of PSD.

Zfra Inhibits the TRAPPC6AΔ-Initiated Pathway of Neurodegeneration.

When WWOX is downregulated in middle age, aggregation of a protein cascade, including TRAPPC6AΔ (TPC6AΔ), TIAF1, and SH3GLB2, may start to occur, and the event lasts more than 30 years, which results in amyloid precursor protein (APP) degradation, amyloid beta (Aß) generation, and neurodegeneration, as shown in Alzheimer's disease (AD). Here, by treating neuroblastoma SK-N-SH cells with neurotoxin MPP+, upregulation and aggregation of TPC6AΔ, along with aggregation of TIAF1, SH3GLB2, Aß, and tau, occurred. MPP+ is an inducer of Parkinson's disease (PD), suggesting that TPC6AΔ is a common initiator for AD and PD pathogenesis. Zfra, a 31-amino-acid zinc finger-like WWOX-binding protein, is known to restore memory deficits in 9-month-old triple-transgenic (3xTg) mice by blocking the aggregation of TPC6AΔ, SH3GLB2, tau, and amyloid ß, as well as inflammatory NF-κB activation. The Zfra4-10 peptide exerted a strong potency in preventing memory loss during the aging of 3-month-old 3xTg mice up to 9 months, as determined by a novel object recognition task (ORT) and Morris water maize analysis. Compared to age-matched wild type mice, 11-month-old Wwox heterozygous mice exhibited memory loss, and this correlates with pT12-WWOX aggregation in the cortex. Together, aggregation of pT12-WWOX may link to TPC6AΔ aggregation for AD progression, with TPC6AΔ aggregation being a common initiator for AD and PD progression.

Exercise Normalized the Hippocampal Renin-Angiotensin System and Restored Spatial Memory Function, Neurogenesis, and Blood-Brain Barrier Permeability in the 2K1C-Hypertensive Mouse.

Hypertension is associated with blood-brain barrier alteration and brain function decline. Previously, we established the 2-kidney,1-clip (2K1C) hypertensive mice model by renin-angiotensin system (RAS) stimulating. We found that 2K1C-induced hypertension would impair hippocampus-related memory function and decrease adult hippocampal neurogenesis. Even though large studies have investigated the mechanism of hypertension affecting brain function, there remains a lack of efficient ways to halt this vicious effect. The previous study indicated that running exercise ameliorates neurogenesis and spatial memory function in aging mice. Moreover, studies showed that exercise could normalize RAS activity, which might be associated with neurogenesis impairment. Thus, we hypothesize that running exercise could ameliorate neurogenesis and spatial memory function impairment in the 2K1C-hypertension mice. In this study, we performed 2K1C surgery on eight-weeks-old C57BL/6 mice and put them on treadmill exercise one month after the surgery. The results indicate that running exercise improves the spatial memory and neurogenesis impairment of the 2K1C-mice. Moreover, running exercise normalized the activated RAS and blood-brain barrier leakage of the hippocampus, although the blood pressure was not decreased. In conclusion, running exercise could halt hypertension-induced brain impairment through RAS normalization.

6-methoxyflavone suppresses neuroinflammation in lipopolysaccharide- stimulated microglia through the inhibition of TLR4/MyD88/p38 MAPK/NF-κB dependent pathways and the activation of HO-1/NQO-1 signaling.

BACKGROUND: Microglia-related neuroinflammation is associated with a variety of neurodegenerative diseases. Flavonoids have demonstrated different pharmacological effects, such as antioxidation, neuroprotection and anti-inflammation However, the effect of flavonoid 6-methoxyflavone (6-MeOF) on microglia-mediated neuroinflammation remain unknown. PURPOSE: The current study aim to study the antineuroinflammatory effects of 6-MeOF in lipopolysaccharide- (LPS-) induced microglia in vitro and in vivo. METHODS: Pretreatment of BV2 microglia cells with 6-MeOF for 1 h then stimulated with LPS (100 ng/ml) for 24 h. The expression levels of pro-inflammatory factors, NO and reactive oxygen species (ROS) were performed by the enzyme-linked immunosorbent assay (ELISA), Griess assay and flow cytometry. Western blotting was used to assess MAPK, NF-κB signal transducer and antioxidant enzymes-related proteins. Analysis of ROS and microglial morphology was confirmed in the zebrafish and mice brain, respectively. RESULTS: Our results demonstrated that 6-MeOF dose-dependently prevent cell death and decreased the levels of pro-inflammatory mediators in LPS-stimulated BV2 microglia cells. Phosphorylated NF-κB/IκB and TLR4/MyD88/p38 MAPK/JNK proteins after exposure to 6-MeOF was suppressed in LPS-activated BV-2 microglial cells. 6-MeOF also presented antioxidant activity by reduction of NO, ROS, iNOS and COX-2 and the induction of the level of HO-1 and NQO1 expressions in LPS-activated BV2 microglial cells. Furthermore, we demonstrated that 6-MeOF inhibited LPS-induced NO generation in an experimental zebrafish model and prevent the LPS-induced microgliosis in the prefrontal cortex and substantia nigra of mice. CONCLUSION: These results explored that 6-MeOF possesses potential as anti-inflammatory and anti-oxidant agents against microglia-associated neuroinflammatory disorders.

Exploring the Impact of Glyoxal Glycation on ß-Amyloid Peptide (Aß) Aggregation in Alzheimer's Disease.

Alzheimer's disease (AD) is characterized by the presence of extracellular senile plaques formed by ß-amyloid (Aß) peptides in the patient's brain. Previous studies have shown that the plaques in the AD brains are colocalized with the advanced glycation end products, which is mainly formed from a series of nonenzymatic reactions of proteins with reducing sugars or reactive dicarbonyls. Glycation was also demonstrated to increase the neurotoxicity of the Aß peptides. To clarify the impact of glycation on Aß aggregation, we synthesized two glycated Aß42 peptides by replacing Lys16 and Lys28 with Nε-carboxymethyllysine respectively to mimic the occurrence of protein glycation. Afterward, we monitored the aggregation kinetics and conformational change for two glycated peptides. We also used fluorescence correlation spectroscopy to probe the early stage of peptide oligomerization and tested their abilities in copper binding and reactive oxygen species production. Our data show that glycation significantly slows down the aggregation process and induces more cytotoxicity especially at position 28. We speculated that the higher toxicity might result from a relatively stable oligomeric form of peptide and not from ROS production. The data shown here emphasized that glycated proteins would be an important therapeutic target in AD treatments.

TDP-43 interacts with amyloid-ß, inhibits fibrillization, and worsens pathology in a model of Alzheimer's disease.

TDP-43 inclusions are found in many Alzheimer's disease (AD) patients presenting faster disease progression and greater brain atrophy. Previously, we showed full-length TDP-43 forms spherical oligomers and perturbs amyloid-ß (Aß) fibrillization. To elucidate the role of TDP-43 in AD, here, we examined the effect of TDP-43 in Aß aggregation and the attributed toxicity in mouse models. We found TDP-43 inhibited Aß fibrillization at initial and oligomeric stages. Aß fibrillization was delayed specifically in the presence of N-terminal domain containing TDP-43 variants, while C-terminal TDP-43 was not essential for Aß interaction. TDP-43 significantly enhanced Aß's ability to impair long-term potentiation and, upon intrahippocampal injection, caused spatial memory deficit. Following injection to AD transgenic mice, TDP-43 induced inflammation, interacted with Aß, and exacerbated AD-like pathology. TDP-43 oligomers mostly colocalized with intracellular Aß in the brain of AD patients. We conclude that TDP-43 inhibits Aß fibrillization through its interaction with Aß and exacerbates AD pathology.

Nitrite Protects Neurons Against Hypoxic Damage Through S-nitrosylation of Caspase-6.

Aims: The coordination of neurons to execute brain functions requires plenty of oxygen. Thus, it is not surprising that the chronic hypoxia resulting from chronic obstructive pulmonary diseases (COPD) can cause neuronal damage. Injury in the cortex can give rise to anxiety and cognitive dysfunction. This study investigated what causes hypoxia-induced neuronal injury and what strategies might be used to protect neurons against such damage. Results: This study found that hypoxia in primary cortical neurons caused neurite retraction, a caspase-6-dependent process. The hypoxic stress activated caspase-6 within the neurite, leading to microtubule disassembly and neurite retraction. The effect of hypoxia on caspase-6 activation, microtubule disassembly, and neurite retraction was alleviated by nitrite treatment. The protective role of nitrite was further supported by the observation that the active-site Cys146 of caspase-6 was S-nitrosylated in hypoxic neuro-2a cells treated with nitrite. We further validated the beneficial effect of nitrite on neuronal function against hypoxic stress in vivo. Using the wild-type or Apo E-/- mice exposed to chronic hypoxia as a model, we demonstrated that supplementing drinking water with nitrite suppressed active caspase-6 in the cortex of the brain, concomitant with the prevention of hypoxia-induced anxiety in the animals. Innovation: These results are the first evidence of a new pathway for the activation of caspase-6 and the first to indicate that nitrite can protect neurons against chronic hypoxic insult. Conclusion: Our findings suggest that nitrite holds great potential for the treatment of diseases such as COPD associated with hypoxia-induced neuronal injury.

Long-Term Moderate Exercise Rescues Age-Related Decline in Hippocampal Neuronal Complexity and Memory.

BACKGROUND: Aging impairs hippocampal neuroplasticity and hippocampus-related learning and memory. In contrast, exercise training is known to improve hippocampal neuronal function. However, whether exercise is capable of restoring memory function in old animals is less clear. OBJECTIVE: Here, we investigated the effects of exercise on the hippocampal neuroplasticity and memory functions during aging. METHODS: Young (3 months), middle-aged (9-12 months), and old (18 months) mice underwent moderate-intensity treadmill running training for 6 weeks, and their hippocampus-related learning and memory, and the plasticity of their CA1 neurons was evaluated. RESULTS: The memory performance (Morris water maze and novel object recognition tests), and dendritic complexity (branch and length) and spine density of their hippocampal CA1 neurons decreased as their age increased. The induction and maintenance of high-frequency stimulation-induced long-term potentiation in the CA1 area and the expressions of neuroplasticity-related proteins were not affected by age. Treadmill running increased CA1 neuron long-term potentiation and dendritic complexity in all three age groups, and it restored the learning and memory ability in middle-aged and old mice. Furthermore, treadmill running upregulated the hippocampal expressions of brain-derived neurotrophic factor and monocarboxylate transporter-4 in middle-aged mice, glutamine synthetase in old mice, and full-length TrkB in middle-aged and old mice. CONCLUSION: The hippocampus-related memory function declines from middle age, but long-term moderate-intensity running effectively increased hippocampal neuroplasticity and memory in mice of different ages, even when the memory impairment had progressed to an advanced stage. Thus, long-term, moderate intensity exercise training might be a way of delaying and treating aging-related memory decline.

Hypertension Accelerates Alzheimer's Disease-Related Pathologies in Pigs and 3xTg Mice.

Epidemiological studies suggest there is an association between midlife hypertension and increased risk of late-life Alzheimer's disease (AD). However, whether hypertension accelerates the onset of AD or is a distinct disease that becomes more prevalent with age (comorbidity) remains unclear. This study aimed to test the possible relationship between hypertension and AD pathogenesis. Two animal models were used in this study. For the first model, 7-month-old Lanyu-miniature-pigs were given the abdominal aortic constriction operation to induce hypertension and their AD-related pathologies were assessed at 1, 2, and 3 months after the operation. The results showed that hypertension was detected since 1 month after the operation in the pigs. Levels of Aß, amyloid precursor protein, RAGE, phosphorylated tau and activated GSK3ß in the hippocampi increased at 3 months after the operation. For the second model, 3xTg mice at the ages of 2, 5, and 7 months were subjected to the "two-kidney-one-clip" operation to induce hypertension. One month after the operation, blood pressure was significantly increased in the 3xTg mice in any age. Aß, amyloid plaque load, and phosphorylated tau levels increased in the operated mice. Furthermore, the operation also induced shrinkage in the dendritic arbor of hippocampal dentate gyrus granule neurons, leakage in the blood-brain barrier, activation in microglia, and impairment in the hippocampus-dependent learning and memory in the 3xTg mice. In conclusion, hypertension accelerates the onset of AD. Blood pressure control during midlife may delay the onset of AD.

Zinc ion rapidly induces toxic, off-pathway amyloid-ß oligomers distinct from amyloid-ß derived diffusible ligands in Alzheimer's disease.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the elderly. Zinc (Zn) ion interacts with the pathogenic hallmark, amyloid-ß (Aß), and is enriched in senile plaques in brain of AD patients. To understand Zn-chelated Aß (ZnAß) species, here we systematically characterized ZnAß aggregates by incubating equimolar Aß with Zn. We found ZnAß40 and ZnAß42 both form spherical oligomers with a diameter of ~12-14 nm composed of reduced ß-sheet content. Oligomer assembly examined by analytical ultracentrifugation, hydrophobic exposure by BisANS spectra, and immunoreactivity of ZnAß and Aß derived diffusible ligands (ADDLs) are distinct. The site-specific 13C labeled solid-state NMR spectra showed that ZnAß40 adopts ß-sheet structure as in Aß40 fibrils. Interestingly, removal of Zn by EDTA rapidly shifted the equilibrium back to fibrillization pathway with a faster kinetics. Moreover, ZnAß oligomers have stronger toxicity than ADDLs by cell viability and cytotoxicity assays. The ex vivo study showed that ZnAß oligomers potently inhibited hippocampal LTP in the wild-type C57BL/6JNarl mice. Finally, we demonstrated that ZnAß oligomers stimulate hippocampal microglia activation in an acute Aß-injected model. Overall, our study demonstrates that ZnAß rapidly form toxic and distinct off-pathway oligomers. The finding provides a potential target for AD therapeutic development.

Zfra restores memory deficits in Alzheimer's disease triple-transgenic mice by blocking aggregation of TRAPPC6AΔ, SH3GLB2, tau, and amyloid ß, and inflammatory NF-κB activation.

INTRODUCTION: Zinc finger-like protein that regulates apoptosis (Zfra) is a naturally occurring 31-amino-acid protein. Synthetic peptides Zfra1-31 and Zfra4-10 are known to effectively block the growth of many types of cancer cells. METHODS: Ten-month-old triple-transgenic (3×Tg) mice for Alzheimer's disease (AD) received synthetic Zfra peptides via tail vein injections, followed by examining restoration of memory deficits. RESULTS: Zfra significantly downregulated TRAPPC6AΔ, SH3GLB2, tau, and amyloid ß (Αß) aggregates in the brains of 3×Tg mice and effectively restored their memory capabilities. Zfra inhibited melanoma-induced neuronal death in the hippocampus and plaque formation in the cortex. Mechanistically, Zfra blocked the aggregation of amyloid ß 42 and many serine-containing peptides in vitro, suppressed tumor necrosis factor-mediated NF-κB activation, and bound cytosolic proteins for accelerating their degradation in ubiquitin/proteasome-independent manner. DISCUSSION: Zfra peptides exhibit a strong efficacy in blocking tau aggregation and amyloid Αß formation and restore memory deficits in 3×Tg mice, suggesting its potential for treatment of AD.

Alzheimer's Amyloid-ß Sequesters Caspase-3 in Vitro via Its C-Terminal Tail.

Amyloid-ß (Aß), the main constituent in senile plaques found in the brain of patients with Alzheimer's disease (AD), is considered as a causative factor in AD pathogenesis. The clinical examination of the brains of patients with AD has demonstrated that caspase-3 colocalizes with senile plaques. Cellular studies have shown that Aß can induce neuronal apoptosis via caspase-3 activation. Here, we performed biochemical and in silico studies to investigate possible direct effect of Aß on caspase-3 to understand the molecular mechanism of the interaction between Aß and caspase-3. We found that Aß conformers can specifically and directly sequester caspase-3 activity in which freshly prepared Aß42 is the most potent. The inhibition is noncompetitive, and the C-terminal region of Aß plays an important role in sequestration. The binding of Aß to caspase-3 was examined by cross-linking and proteolysis and by docking and all-atom molecular dynamic simulations. Experimental and in silico results revealed that Aß42 exhibits a higher binding affinity than Aß40 and the hydrophobic C-terminal region plays a key role in the caspase-Aß interaction. Overall, our study describes a novel mechanism demonstrating that Aß sequesters caspase-3 activity via direct interaction and facilitates future therapeutic development in AD.

Estrogen ameliorates microglial activation by inhibiting the Kir2.1 inward-rectifier K(+) channel.

Microglial activation is implicated in the pathogenesis of Parkinson's disease (PD). Although the etiology of PD remains unclear, age and male gender are known PD risk factors. By comparing microglia and dopaminergic (DA) neurons in the substantia nigra (SN) of male and female mice of different ages, we found that the degrees of microglial activation and DA neuron loss increased with age in both genders, but were more pronounced in males, as were peripheral lipopolysaccharide (LPS)-induced microglial activation and DA neuron loss. A bilateral ovariectomy (OVX) eliminated the female-associated protection against age- and LPS-induced microglial activation, which suggests that ovary hormones are involved in gender-specific responses. Treating female mice with 17ß-estradiol supplements reduced the age-associated microglial activation in OVX mice. Moreover, pretreating mouse BV2 microglial cells with 17ß-estradiol inhibited LPS-induced elevation of Toll-like receptor 4, phosphorylated p38, and TNF-α levels. We then examined the effect of 17ß-estradiol on inward-rectifier K(+) channel Kir2.1, a known regulator of microglial activation. We found that 17ß-estradiol inhibited the Kir2.1 activity of BV2 cells by reducing the probability that the channel would be open. We conclude that age- and inflammation-associated microglial activation is attenuated by ovarian estrogen, because it inhibits Kir2.1.

Neurodegeneration in Amygdala Precedes Hippocampus in the APPswe/ PS1dE9 Mouse Model of Alzheimer's Disease.

Both the hippocampus and amygdala are early vulnerable brain regions in the development of Alzheimer's disease (AD). However, previous studies mainly focused on characterizing the hippocampus in the pathophysiology of AD, leaving the amygdala less explored. Here, we characterized the structures and functions of neurons in the hippocampus and amygdala of young (2, 3 and 4 months of age) APP/PS1 double transgenic (Tg) mice, a widely used AD mouse model. Compared to wild-type littermates (Wt ), Tg mice performed worse in amygdala-dominant memory at all three ages, while hippocampus-dominant memory remained intact until 4-month-old. Likewise, the dendritic arbors of neurons in the basolateral amygdala were reduced in Tg mice as early as 2-months-old, while the dendritic arbors of neurons in the hippocampal CA1 and CA3 regions were relatively intact. BDNF signaling pathways (e.g. AKT and PKC) were reduced in the amygdala, but not in the hippocampus, of young Tg mice. Furthermore, reduction of 5-HT and elevation of Aß levels also occurred earlier in the amygdala and were more pronounced than those in the hippocampus. Negative correlations between the levels of 5-HT and Aß were evident in the amygdala, but not in the hippocampus. Taken together, these results suggest that neurodegeneration occurs earlier in the amygdala than in the hippocampus. We suggest that amygdala function should be incorporated into the cognitive screening tool for the diagnosis of mild cognitive impairment due to AD.

Running exercise delays neurodegeneration in amygdala and hippocampus of Alzheimer's disease (APP/PS1) transgenic mice.

Alzheimer's disease (AD) is an age-related neurodegenerative disease. Post-mortem examination and brain imaging studies indicate that neurodegeneration is evident in the hippocampus and amygdala of very early stage AD patients. Exercise training is known to enhance hippocampus- and amygdala-associated neuronal function. Here, we investigated the effects of exercise (running) on the neuronal structure and function of the hippocampus and amygdala in APP/PS1 transgenic (Tg) mice. At 4-months-old, an age before amyloid deposition, the amygdala-associated, but not the hippocampus-associated, long-term memory was impaired in the Tg mice. The dendritic complexities of the amygdalar basolateral neurons, but not those in the hippocampal CA1 and CA3 neurons, were reduced. Furthermore, the levels of BDNF/TrkB signaling molecules (i.e. p-TrkB, p-Akt and p-PKC) were reduced in the amygdala, but not in the hippocampus of the 4-month-old Tg mice. The concentrations of Aß40 and Aß42 in the amygdala were higher than those in the hippocampus. Ten weeks of treadmill training (from 1.5- to 4-month-old) increased the hippocampus-associated memory and dendritic arbor of the CA1 and CA3 neurons, and also restored the amygdala-associated memory and the dendritic arbor of amygdalar basolateral neurons in the Tg mice. Similarly, exercise training also increased the levels of p-TrkB, p-AKT and p-PKC in the hippocampus and amygdala. Furthermore, exercise training reduced the levels of soluble Aß in the amygdala and hippocampus. Exercise training did not change the levels of APP or RAGE, but significantly increased the levels of LRP-1 in both brain regions of the Tg mice. In conclusion, our results suggest that tests of amygdala function should be incorporated into subject selection for early prevention trials. Long-term exercise protects neurons in the amygdala and hippocampus against AD-related degeneration, probably via enhancements of BDNF signaling pathways and Aß clearance. Physical exercise may serve as a means to delay the onset of AD.

Apolipoprotein C-III is an amyloid-ß-binding protein and an early marker for Alzheimer's disease.

It has been demonstrated that peripheral injection of anti-amyloid-ß (Aß) antibodies to patients with Alzheimer's disease (AD) and AD transgenic mice facilitate Aß clearance. We hypothesized that peripheral circulating Aß-binding proteins also possess the ability to enhance Aß clearance and the levels of circulating Aß-binding proteins could serve as early AD biomarkers. Circulating Aß-binding proteins were isolated from plasma and identified by LC-MS/MS. Their levels were compared among non-demented individuals without AD family history (ND), with AD family history (ND-FH), and patients with mild AD. The results showed that most of the identified Aß-binding proteins were apolipoproteins, i.e., apoA-I, apoB-100, apoC-III, and apoE. Aß bound preferentially to apoA-I-enriched HDL, followed by apoC-III- and apoE-enriched VLDL, and bound less favorably to apoB-100-enriched LDL. Levels of apoA-I were reduced in AD patients and could be used to discriminate AD from ND groups (AUC: 0.93); whereas levels of apoC-III were reduced in both ND-FH and AD groups and could be used to differentiate ND-FH from ND individuals (AUC: 0.81). Both the levels of apoA-1 and apoC-III positively correlated with CASI and MMSE scores. In conclusion, these results suggest that plasma apoA-I could be a sensitive AD biomarker and individuals with low plasma levels of apoC-III are at risk for AD.

Cerebrovascular pathology and amyloid plaque formation in Alzheimer's disease.

Accumulation, aggregation and deposition of the amyloid-ß (Aß) peptides in the brain are widely accepted as the central events in the pathogenesis of Alzheimer's disease (AD). Any factor that is capable of causing these events is potentially a risk factor for AD. In the last decade, evidence has accumulated to support the association between cerebral vascular diseases (CVD) and AD. CVD is known to induce amyloid deposition and affects the age of onset for sporadic AD; whereas, amyloid deposition has been shown to cause cerebrovascular degeneration. In this review, we propose a positive feedback loop between CVD and amyloid deposition. The disease cycle could be triggered by aging and/or other environmental factor-associated CVD, as in late-onset sporadic AD patients, or by over production of Aß, as in the familial AD patients and amyloid precursor protein transgenic animals.

Coarctation-induced degenerative abdominal aortic aneurysm in a porcine model.

OBJECTIVE: Hemodynamic stress participates in the initiation and progression of aneurysmal degeneration. Coarctation increases flow-mediated stress on the aortic wall. We tested the hypothesis that prolonged coarctation of an infrarenal abdominal aorta (AA) segment leads to abdominal aortic aneurysm (AAA) formation in mini pigs. METHODS: An asymmetric, funnel-shaped flow path was created by constricting the infrarenal AA segment of Taiwanese Lanyu mini pigs (age, 7-10 months; male and female) wrapped with an 8-mm-wide expanded polytetrafluoroethylene Teflon strip for 4 weeks (4w), 8 weeks (8w), and 12 weeks (12w) (seven pigs per group). This mimics the tortuous aneurysm neck in human AAA, which increases downstream flow-mediated stress. Significant flow disturbance resulting from moderate coarctation was indicated by a pulsatility index reduced to one third the inherent levels. Sham control pigs received Teflon wrapping without coarctation. RESULTS: Aneurysm characterized by progressive medial degeneration occurred at the terminal AA after 12w coarctation. The outer dimension enlargement of the distal AA exceeded 50% compared with that of the proximal AA at 4w, 8w, and 12w postcoarctation (sham, 1.0; 4w, 1.7 ± 0.08; 8w, 1.5 ± 0.09; 12w, 1.7 ± 0.01). Lumen ratio of the distal-to-suprarenal AA increased time dependently, with 12w postcoarctation exhibiting significant increase (sham, 1.0 ± 0.05; 4w, 1.1 ± 0.11; 8w, 1.4 ± 0.20; 12w, 1.5 ± 0.09). In the distal AA, elastic lamellae exhibited fragmentation at 4w and more pronounced fragmentation with decreased density at 8w and 12w postcoarctation. Medial collagen density exhibited the trend to increase at 4w and 8w but was reversed at 12w postcoarctation. Smooth muscle exhibited disarray and nuclear density decrease at 8w and 12w postcoarctation (sham, 6966 ± 888/mm; 4w, 5747 ± 1340/mm; 8w, 4153 ± 323/mm; 12w, 4083 ± 465/mm). Gelatin zymography revealed that matrix metalloproteinase-9 activity markedly increased at 4w postcoarctation. CONCLUSIONS: Prolonged moderate coarctation caused regional hemodynamic stress and thereby induced degenerative AAA in the terminal AA.