The β-amyloid precursor protein analog P165 improves impaired insulin signal transduction in type 2 diabetic rats

CaMKIV/CREB/BDNF signaling pathway expression in prefrontal cortex, amygdala, hippocampus and hypothalamus in streptozotocin-induced diabetic mice with anxious-like behavior

Individuals with diabetes mellitus (DM) tend to manifest anxiety and depression, which could be related to changes in the expression of calcium/calmodulin-dependent protein kinase IV (CaMKIV), transcription factor cyclic AMP-responsive element binding protein (CREB), phosphorylated CREB (pCREB) and brain-derived neurotrophic factor (BDNF) in different brain regions. The objective of this study was to determine whether mice with type 1 diabetes (T1DM) induced with streptozotocin show a profile of anxious-type behaviors and alterations in the expression/activity of CaMKIV, CREB, pCREB and BDNF in different regions of the brain (prefrontal cortex, amygdala, hippocampus and hypothalamus) in comparison to non-diabetic mice (NDB). Mice with 3 months of chronic DM showed an anxious-like behavioral profile in two anxiety tests (Open Field and Elevated Plus Maze), when compared to NDB. There were significant differences in the expression of cell signaling proteins: diabetic mice had a lower expression of CaMKIV in the hippocampus, a greater expression of CREB in the amygdala and hypothalamus, as well as a lower pCREB/CREB in hypothalamus than NDB mice (P < 0.05). This is the first study evaluating the expression of CaMKIV in the brain of animals with DM, who presented lower expression of this protein in the hippocampus. In addition, it is the first time that CREB was evaluated in amygdala and hypothalamus of animals with DM, who presented a higher expression. Further research is necessary to determine the possible link between expression of CaMKIV and CREB, and the behavioral profile of anxiety in diabetic animals.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Reducing CXCR4 Resulted in Impairing Proliferation and Promoting Aging

BACKGROUND

Alzheimer's disease (AD) is one of the most common and devastating aging related neurodegenerative diseases. Aging is a natural physiological process, a progressive deterioration of the overall homeostatic brain mechanisms, accompanied by cognitive decline. CXCL12/CXCR4 chemokine signaling plays a critical role in modulating various nervous system developmental processes and in regulating synaptic plasticity.

RESULTS

In this article, we have firstly shown that CXCR4 is critical for cell proliferation and cytotoxicity in the SH-SY5Y cell model. Moreover, it has been firstly demonstrated that CXCR4 colocalized with AKT on the membrane and regulated the AKT activation to prevent aging and AD.

DISCUSSION

In a word, we supply a novel pathway that CXCR4 pathway stimulated by CXCL12 regulated AKT activation, CREB phosphorylation and P53 level to affect the process of aging and AD. Therefore, CXCR4 may be a novel target and biomarker for the diagnosis and treatment of AD and aging.

Cognitive function and insulin resistance in elderly patients with type 2 diabetes

PURPOSE

To explore the relationship between cognitive impairment and insulin resistance (IR) in elderly patients with type-2 diabetes mellitus.

MATERIALS AND METHODS

Two hundred and twelve elderly patients with type-2 diabetes were enrolled in this study and assigned into either the cognitive impairment group (n = 100) or the normal cognitive group (n = 112). Gender, age, education, body mass index (BMI), total cholesterol, triglyceride, low-density lipoprotein cholesterol, creatinine (Cr), fasting plasma glucose, fasting insulin (FINS) and homeostasis model of assessment for IR index (HOMA-IR) were compared between the two groups. Multifactorial logistic regression analysis was performed.

RESULTS

In cognitive impairment group, education level (33.00 vs 53.57%, p < 0.01) was lower, the level of BMI [(28.7 ± 4.5) kg/m² vs (23.9 ± 3.7) kg/m², p < 0.01], FINS [(21.8 ± 5.3) mU/L vs (12.9 ± 3.9) mU/L, p < 0.01], HOMA-IR [(6.9 ± 1.7) vs (3.9 ± 0.9), p < 0.01] were higher than the control group. In the logistic regression, education level (B = -0.996, p = 0.03), FINS (B = 1.120, p < 0.01) and HOMA-IR (B = 1.301, p < 0.01) were independent factors.

CONCLUSIONS

Our study demonstrates that the education level, FINS and HOMA-IR were independent factors of cognitive impairment in elderly patients with type-2 diabetes. IR is an important risk factor and higher education level in a protective factor for the cognitive impairment in elderly patients with type-2 diabetes.

Neurotrophic effects of amyloid precursor protein peptide 165 in vitro

Diabetic encephalopathy is one of the risk factors for Alzheimer's disease. Our previous findings indicated that animals with diabetic encephalopathy exhibit learning and memory impairment in addition to hippocampal neurodegeneration, both of which are ameliorated with amyloid precursor protein (APP) 17-mer (APP17) peptide treatment. Although APP17 is neuroprotective, it is susceptible to enzymatic degradation. Derived from the active sequence structure of APP17, we have previously structurally transformed and modified several APP5-mer peptides (APP328-332 [RERMS], APP 5). We have developed seven different derivatives of APP5, including several analogs. Results from the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human neuroblastoma SH-SY5Y cells in the present study showed that P165 was the most neuroprotective APP5 derivative. Furthermore, we tested the effects of APP5 and P165 on the number of cells and the release of lactate dehydrogenase. Western immunoblot analyses were also performed. The digestion rates of P165 and APP5 were determined by the pepsin digestion test. P165 resisted pepsin digestion significantly more than APP5. Therefore, P165 may be optimal for oral administration. Overall, these findings suggest that P165 may be a potential drug for the treatment of diabetic encephalopathy.