Cyclin-dependent kinase-5 is a key molecule in tumor necrosis factor-α-induced insulin resistance

Stellate Ganglia and Cardiac Sympathetic Overactivation in Heart Failure

Heart failure (HF) is a major public health problem worldwide, especially coronary heart disease (myocardial infarction)-induced HF with reduced ejection fraction (HFrEF), which accounts for over 50% of all HF cases. An estimated 6 million American adults have HF. As a major feature of HF, cardiac sympathetic overactivation triggers arrhythmias and sudden cardiac death, which accounts for nearly 50–60% of mortality in HF patients. Regulation of cardiac sympathetic activation is highly integrated by the regulatory circuitry at multiple levels, including afferent, central, and efferent components of the sympathetic nervous system. Much evidence, from other investigators and us, has confirmed the afferent and central neural mechanisms causing sympathoexcitation in HF. The stellate ganglion is a peripheral sympathetic ganglion formed by the fusion of the 7th cervical and 1st thoracic sympathetic ganglion. As the efferent component of the sympathetic nervous system, cardiac postganglionic sympathetic neurons located in stellate ganglia provide local neural coordination independent of higher brain centers. Structural and functional impairments of cardiac postganglionic sympathetic neurons can be involved in cardiac sympathetic overactivation in HF because normally, many effects of the cardiac sympathetic nervous system on cardiac function are mediated via neurotransmitters (e.g., norepinephrine) released from cardiac postganglionic sympathetic neurons innervating the heart. This review provides an overview of cardiac sympathetic remodeling in stellate ganglia and potential mechanisms and the role of cardiac sympathetic remodeling in cardiac sympathetic overactivation and arrhythmias in HF. Targeting cardiac sympathetic remodeling in stellate ganglia could be a therapeutic strategy against malignant cardiac arrhythmias in HF.

Effects of dietary restriction on cognitive function: a systematic review and meta-analysis

BACKGROUND

Potential positive link between cognitive function and dietary restriction has been widely concerned. The present study describes a systematic review and preliminary meta-analysis to assess the efficacy of dietary restriction on cognitive function. We classified dietary restrictions as Calories Restriction (CR) and Intermittent Fasting (IF).

METHOD

This systematic review and meta-analysis conducted following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Statement (PRISMA) Checklist, Databases including PubMed, Embase, Web of Science, and the Cochrane Library were searched for randomized controlled trials (RCTs) assessing the cognition effectiveness of dietary restriction from database inception to Sep 2021.

RESULT

Eleven RCTs met the inclusion criteria in the systematic review and meta-analysis. The overall effect of dietary restriction on cognitive function is SMD = 0.22 (95% CI: 0.09-0.34, p < 0.01). The effect on global function SMD = 0.35 (95% CI: 0.04-0.65, p < 0.05) and memory SMD = 0.18 (95% CI: 0.00-0.35, p = 0.05) is significant. MCI showed the best effectiveness SMD = 0.36 (95% CI: 0.05-0.68, p < 0.05), followed by the normal weight population SMD = 0.28 (95% CI: 0.03-0.52, p < 0.05) and overweight population SMD = 0.20 (95% CI: 0.06-0.34, p < 0.01). No statistically significant difference showed between IF and CR (p > 0.05).

CONCLUSION

Our study demonstrated that dietary restriction has varying degrees of positive effect on cognitive function in overweight/normal-weight people and MCI. However, it should be cautious when generalizing to other populations. Additional high-quality, large-scale, cohort and intervention studies are needed to further assess the effectiveness of dietary restriction on cognition.

IL-34 was high in serum of women with polycystic ovary syndrome and may function as potential diagnostic biomarker and therapeutic target

BACKGROUND

Polycystic ovary syndrome (PCOS) is one of the most prevalent endocrine disorders in females of reproductive age, with a prevalence of 20%-33% in the general population. Interleukin (IL)-34 is a recently explored proinflammatory cytokine and is an important modulator in different disease types. However, the function of IL-34 in PCOS has yet to be investigated.

OBJECTIVE

The purpose of this study was to determine the IL-34 serum level in women with PCOS and to compare it to that of a relatively healthy control group. Focusing on its relationship with IL-6, TNF-α, and IL-1β and homeostatic model assessment for insulin resistance (HOMA-IR), triglyceride, and low-density lipoprotein cholesterol (LDL-C).

MATERIALS AND METHODS

In this study, blood samples were obtained from 100 women with PCOS and 100 healthy control women for the purpose of estimating their serum levels of IL-34, IL-6, TNF-α, and IL-1β using the enzyme-linked immunosorbent assay technique.

RESULTS

Serum levels of IL-34, IL-6, TNF-α, and IL-1β were all higher in PCOS women than in healthy controls, and the difference was highly statistically significant. Serum IL-34 concentration was positively correlated with IL-6, TNF-α, and IL-1β concentration. Additionally, serum concentrations of IL-34 were positively correlated with HOMA-IR, triglyceride, and LDL-C.

CONCLUSION

When compared to normal women, IL-34, IL-6, TNF-α, and IL-1β levels were highly statistically significant in PCOS, and these high levels were associated with other cytokines (IL-6, TNF-α, and IL-1β), HOMA-IR, triglyceride, and LDL-C.

MiRNA-27a mediates insulin resistance in 3T3-L1 cells through the PPARγ

The biological actions of insulin have been originated by activation of membrane receptors, which trigger a diversity of signaling pathways in facilitating their biological activities. Insulin homeostasis functions in promoting metabolism balance and promotes cell growth and proliferation. If these mechanisms are reformed, this could lead to insulin resistance as a result of defective insulin signaling triggered by mutations in receptors or effector molecules located downstream or by abnormal posttranslational modifications. The purpose of this is to preliminarily investigate the mechanism of miRNA-27a-mediating insulin resistance in 3T3-L1 cells. Insulin resistance in 3T3-L1 adipocytes as a cell model was induced by tumor necrosis factor-alpha (TNF-α) and the miRNA-27a expression in 3T3-L1 adipocytes had been experiential. The regulation of peroxisome proliferator-activated receptor-gamma (PPARγ) mRNA by miRNA-27a had been studied by reverse transcription receptor polymerase chain reaction (RT-PCR). MiRNA-27a was up-regulated in 3T3-L1 cells, miRNA-27a mimics reserved expression of PPARγ mRNA, and miRNA-27a inhibitors up-regulated the expression of PPARγ mRNA. The insulin resistance in 3T3-L1 cells mediated by miRNA-27a may be achieved by targeting PPARγ.

CDK5 inhibition improves glucose uptake in insulin-resistant neuronal cells via ERK1/2 pathway

Role of CDK5 and its inhibition in various neuronal processes and functions are well established. However, role of CDK5 and its inhibition in neuronal insulin-signaling and-resistance is not yet explored. In the present study, we investigated the effect of CDK5 inhibition in neuronal insulin signaling, specifically insulin-stimulated glucose uptake. CDK5 expression in neuro-2a cells was increased under insulin-resistant state, developed by chronic treatment of insulin, confirming the crucial role of CDK5 in insulin resistance in neuronal cells. However, whether increased expression of CDK5 in hyperinsulinemia-mediated insulin-resistant conditions is a cause or a consequence, is still an unanswered question. We showed that CDK5 inhibition did not affect basal insulin signaling; however, insulin-stimulated glucose uptake enhanced in insulin-resistant cells. Moreover, CDK5 inhibition could improve glucose uptake, the ultimate outcome of insulin signaling, in insulin-resistant neuro-2a cells. We first time showed that CDK5 inhibition by roscovitine could ameliorate insulin resistance and increase glucose uptake in neuronal cells via ERK1/2 pathway. Our study provides intriguing insights about the effect of CDK5 inhibition on neuronal insulin resistance and opens up a new paradigm to develop new therapeutic strategies for neuronal insulin resistance and associated pathophysiological conditions.

Insulin Resistance and Diabetes Mellitus in Alzheimer's Disease

Type 2 diabetes mellitus is a progressive disease that is characterized by the appearance of insulin resistance. The term insulin resistance is very wide and could affect different proteins involved in insulin signaling, as well as other mechanisms. In this review, we have analyzed the main molecular mechanisms that could be involved in the connection between type 2 diabetes and neurodegeneration, in general, and more specifically with the appearance of Alzheimer's disease. We have studied, in more detail, the different processes involved, such as inflammation, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction.

Polycystic ovary syndrome associated with increased adiposity interferes with serum levels of TNF-alpha and IL-6 differently from leptin and adiponectin

Objective The aim of this study was to investigate polycystic ovary syndrome (PCOS) and to explore the relationship between body fat percentage and metabolic markers. Subjects and methods Sedentary women were assigned to PCOS (N = 60) and CONTROL (N = 60) groups. Each group was subdivided into three subgroups according to body fat percentage (22-27%, 27-32% and 32-37%). The protocol consisted of assessments of glucose, insulin, androgens, follicle stimulating hormone (FSH), luteinizing hormone (LH), 17-hydroxyprogesterone (17-OHP), leptin, adiponectin, tumor necrosis factor (TNF-α) and interleukin-6 (IL-6). Results The PCOS subgroups showed higher concentrations of androgens, LH and 17-OHP. Leptin showed direct relationship with increased body fat percentage, whereas adiponectin showed the inverse effect. However, both were unaffected by PCOS. TNF-α and IL-6 were higher in PCOS women and showed a direct relationship with increased body fat percentage. Glucose showed direct relationship with body fat percentage, whereas insulin presented higher values in PCOS women and direct relationship with increased body fat percentage. Conclusions Our findings indicate that PCOS and body fat percentage directly influence concentrations of insulin, TNF-α and IL-6, whereas leptin and adiponectin are influenced only by the increase in body fat percentage in these women. Arch Endocrinol Metab. 2020;64(1):4-10.

Role of cyclin-dependent kinases (CDKs) in hepatocellular carcinoma: Therapeutic potential of targeting the CDK signaling pathway

Liver cancer is the fourth leading cause of cancer related mortality in the world, with hepatocellular carcinoma (HCC) representing the most common primary subtype. Two-thirds of HCC patients have advanced disease when diagnosed, and for these patients, treatment strategies remain limited. In addition, there is a high incidence of tumor recurrence after surgical resection with the current treatment regimens. The development of novel and more effective agents is required. Cyclin-dependent kinases (CDKs) constitute a family of 21 different protein kinases involved in regulating cell proliferation, apoptosis, and drug resistance, and are evaluated in preclinical and clinical trials as chemotherapeutics. To summarize and discuss the therapeutic potential of targeting CDKs in HCC, recent published articles identified from PubMed were comprehensively reviewed. The key words included hepatocellular carcinoma, cyclin-dependent kinases, and CDK inhibitors. This review focuses on the emerging evidence from studies describing the genetic and functional aspects of CDKs in HCC. We also present an overview of CDK inhibitors that have shown efficacy in laboratory studies of HCC. Although many of the studies assessing CDK-targeting therapies in HCC are at the preclinical stage, there is significant evidence that CDK inhibitors used alone or in combination with established chemotherapy drugs could have significant applications in HCC.

Enhanced Glucose Transport, but not Phosphorylation Capacity, Ameliorates Lipopolysaccharide-Induced Impairments in Insulin-Stimulated Muscle Glucose Uptake

Lipopolysaccharide (LPS) is known to impair insulin-stimulated muscle glucose uptake (MGU). We determined if increased glucose transport (GLUT4) or phosphorylation capacity (hexokinase II; HKII) could overcome the impairment in MGU. We used mice that overexpressed GLUT4 (GLUT4) or HKII (HK) in skeletal muscle. Studies were performed in conscious, chronically catheterized (carotid artery and jugular vein) mice. Mice received an intravenous bolus of either LPS (10 μg/g body weight) or vehicle (VEH). After 5 h, a hyperinsulinemic-euglycemic clamp was performed. As MGU is also dependent on cardiovascular function that is negatively affected by LPS, cardiac function was assessed using echocardiography. LPS decreased whole body glucose disposal and MGU in wild-type (WT) and HK mice. In contrast, the decrease was attenuated in GLUT4 mice. Although membrane-associated GLUT4 was increased in VEH-treated GLUT4 mice, LPS impaired membrane-associated GLUT4 in GLUT4 mice to the same level as LPS-treated WT mice. This suggested that overexpression of GLUT4 had further benefits beyond preserving transport activity. In fact, GLUT4 overexpression attenuated the LPS-induced decrease in cardiac function. The maintenance of MGU in GLUT4 mice following LPS was accompanied by sustained anaerobic glycolytic flux as suggested by increased muscle Pdk4 expression, and elevated lactate availability. Thus, enhanced glucose transport, but not phosphorylation capacity, ameliorates LPS-induced impairments in MGU. This benefit is mediated by long-term adaptations to the overexpression of GLUT4 that sustain muscle anaerobic glycolytic flux and cardiac function in response to LPS.

Therapeutic potential of the dual peroxisome proliferator activated receptor (PPAR)α/γ agonist aleglitazar in attenuating TNF-α-mediated inflammation and insulin resistance in human adipocytes

Adipose tissue inflammation is a mechanistic link between obesity and its related sequelae, including insulin resistance and type 2 diabetes. Dual ligands of peroxisome proliferator activated receptor (PPAR)α and γ, combining in a single molecule the metabolic and inflammatory-regulatory properties of α and γ agonists, have been proposed as a promising therapeutic strategy to antagonize adipose tissue inflammation. Here we investigated the effects of the dual PPARα/γ agonist aleglitazar on human adipocytes challenged with inflammatory stimuli. Human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were treated with aleglitazar or - for comparison - the selective agonists for PPARα or γ fenofibrate or rosiglitazone, respectively, for 24h before stimulation with TNF-α. Aleglitazar, at concentrations as low as 10nmol/L, providing the half-maximal transcriptional activation of both PPARα and PPARγ, reduced the stimulated expression of several pro-inflammatory mediators including interleukin (IL)-6, the chemokine CXC-L10, and monocyte chemoattractant protein (MCP)-1. Correspondingly, media from adipocytes treated with aleglitazar reduced monocyte migration, consistent with suppression of MCP-1 secretion. Under the same conditions, aleglitazar also reversed the TNF-α-mediated suppression of insulin-stimulated ser473 Akt phosphorylation and decreased the TNF-α-induced ser312 IRS1 phosphorylation, two major switches in insulin-mediated metabolic activities, restoring glucose uptake in insulin-resistant adipocytes. Such effects were similar to those obtainable with a combination of single PPARα and γ agonists. In conclusion, aleglitazar reduces inflammatory activation and dysfunction in insulin signaling in activated adipocytes, properties that may benefit diabetic and obese patients. The effect of aleglitazar was consistent with dual PPARα and γ agonism, but with no evidence of synergism.

Cdk5 controls IL-2 gene expression via repression of the mSin3a-HDAC complex

Cyclin-dependent kinase 5 (Cdk5) is a unique member of a family of serine/threonine cyclin-dependent protein kinases. We previously demonstrated disruption of Cdk5 gene expression in mice impairs T-cell function and ameliorates T-cell-mediated neuroinflammation. Here, we show Cdk5 modulates gene expression during T-cell activation by impairing the repression of gene transcription by histone deacetylase 1 (HDAC1) through specific phosphorylation of the mSin3a protein at serine residue 861. Disruption of Cdk5 activity in T-cells enhances HDAC activity and binding of the HDAC1/mSin3a complex to the IL-2 promoter, leading to suppression of IL-2 gene expression. These data point to essential roles for Cdk5 in regulating gene expression in T-cells and transcriptional regulation by the co-repressor mSin3a.

Insulin-mimetic and anti-inflammatory potential of a vanadyl-Schiff base complex for its application against diabetes

Insulin-mimetic and anti-inflammatory potential of vanadium oxo complex (VOTP) enhances the GLUT4 translocation by inducing the phosphorylation of tyrosine moiety in insulin receptor substrate (IRS1).

High-mobility group nucleosome-binding domain 2 protein inhibits the invasion of Klebsiella pneumoniae into mouse lungs in vivo

Since bacterial invasion into host cells is a critical step in the infection process and the predominance of multiple-antibiotic-resistant Klebsiella (K.) pneumoniae strains, using molecular agents to interfere with K. pneumoniae invasion is an attractive approach for the prevention of infection and suppress the immune inflammatory response. In previous studies by our group, high-mobility group nucleosome-binding domain 2 (HMGN2) protein was shown to exhibit anti-bacterial activity in vitro. The objective of the present study was to investigate the effects of HMGN2 protein on the invasion of K. pneumoniae 03183 in vivo. The results showed that pre-treatment with 128 µg/ml HMGN2 significantly reduced K. pneumoniae 03183 invasion into mouse lungs and increased the mRNA expression of CXCL1 and LCN2 within 2 h. Immunohistochemical staining showed that F-actin expression was significantly decreased, and fluorescence microscopy and western blot analysis further demonstrated that HMGN2 significantly blocked K. pneumoniae 03183-induced actin polymerization. These changes implied that HMGN2 may provide protection against K. pneumoniae 03183 infection in vivo.

Adipocyte SIRT1 knockout promotes PPARγ activity, adipogenesis and insulin sensitivity in chronic-HFD and obesity

OBJECTIVE

Adipose tissue is the primary site for lipid deposition that protects the organisms in cases of nutrient excess during obesogenic diets. The histone deacetylase Sirtuin 1 (SIRT1) inhibits adipocyte differentiation by targeting the transcription factor peroxisome proliferator activated-receptor gamma (PPARγ).

METHODS

To assess the specific role of SIRT1 in adipocytes, we generated Sirt1 adipocyte-specific knockout mice (ATKO) driven by aP2 promoter onto C57BL/6 background. Sirt1 (flx/flx) aP2Cre (+) (ATKO) and Sirt1 (flx/flx) aP2Cre (-) (WT) mice were fed high-fat diet for 5 weeks (short-term) or 15 weeks (chronic-term). Metabolic studies were combined with gene expression analysis and phosphorylation/acetylation patterns in adipose tissue.

RESULTS

On standard chow, ATKO mice exhibit low-grade chronic inflammation in adipose tissue, along with glucose intolerance and insulin resistance compared with control fed mice. On short-term HFD, ATKO mice become more glucose intolerant, hyperinsulinemic, insulin resistant and display increased inflammation. During chronic HFD, WT mice developed a metabolic dysfunction, higher than ATKO mice, and thereby, knockout mice are more glucose tolerant, insulin sensitive and less inflamed relative to control mice. SIRT1 attenuates adipogenesis through PPARγ repressive acetylation and, in the ATKO mice adipocyte PPARγ was hyperacetylated. This high acetylation was associated with a decrease in Ser273-PPARγ phosphorylation. Dephosphorylated PPARγ is constitutively active and results in higher expression of genes associated with increased insulin sensitivity.

CONCLUSION

Together, these data establish that SIRT1 downregulation in adipose tissue plays a previously unknown role in long-term inflammation resolution mediated by PPARγ activation. Therefore, in the context of obesity, the development of new therapeutics that activate PPARγ by targeting SIRT1 may provide novel approaches to the treatment of T2DM.

Identification of nuclear hormone receptor pathways causing insulin resistance by transcriptional and epigenomic analysis

Insulin resistance is a cardinal feature of Type 2 diabetes (T2D) and a frequent complication of multiple clinical conditions, including obesity, ageing and steroid use, among others. How such a panoply of insults can result in a common phenotype is incompletely understood. Furthermore, very little is known about the transcriptional and epigenetic basis of this disorder, despite evidence that such pathways are likely to play a fundamental role. Here, we compare cell autonomous models of insulin resistance induced by the cytokine tumour necrosis factor-α or by the steroid dexamethasone to construct detailed transcriptional and epigenomic maps associated with cellular insulin resistance. These data predict that the glucocorticoid receptor and vitamin D receptor are common mediators of insulin resistance, which we validate using gain- and loss-of-function studies. These studies define a common transcriptional and epigenomic signature in cellular insulin resistance enabling the identification of pathogenic mechanisms.

Secreted nucleobindin-2 inhibits 3T3-L1 adipocyte differentiation

Nucleobindin-2 is a 420 amino acid EF-hand Ca2+ binding protein that can be further processed to generate an 82 amino terminal peptide termed Nesfatin-1. To examine the function of secreted Nucleobindin-2 in adipocyte differentiation, cultured 3T3-L1 cells were incubated with either 0 or 100 nM of GST, GST-Nucleobindin-2, prior to and during the initiation of adipocyte differentiation. Nucleobindin-2 treatment decreased neutral lipid accumulation (Oil-Red O staining) and expression of several marker genes for adipocyte differentiation (PPARγ, aP2, and adipsin). When Nucleobindin-2 was constitutively secreted into cultured medium, cAMP content and insulin stimulated CREB phosphorylation were significantly reduced. On the other hand, intracellularly overexpressed Nucleobindin-2 failed to affect cAMP content and CREB phosphorylation. Taken together, these data indicate that secreted Nucleobindin-2 is a suppressor of adipocyte differentiation through inhibition of cAMP production and insulin signal.

Stop feeding cancer: pro-inflammatory role of visceral adiposity in liver cancer

Liver cancer is the fifth most common cancer in the world with an estimated over half a million new cases diagnosed every year. Due to the difficulty in early diagnosis and lack of treatment options, the prevalence of liver cancer continues to climb with a 5-year survival rate of between 6% and 11%. Coinciding with the rise of liver cancer, the prevalence of obesity has rapidly increased over the past two decades. Evidence from epidemiological studies demonstrates a higher risk of hepatocellular carcinoma (HCC) in obese individuals. Obesity is recognised as a low-grade inflammatory disease, this is of particular relevance as inflammation has been proposed as the seventh hallmark of cancer development with abdominal visceral adiposity considered as an important source of pro-inflammatory stimuli. Emerging evidence points towards the direct role of visceral adipose tissue rather than generalised body fat in carcinogenesis. Cytokines such as IL-6 and TNF-α secreted from visceral adipose tissue have been demonstrated to induce a chronic inflammatory condition predisposing the liver to a protumourigenic milieu. This review focuses on excess visceral adiposity rather than simple obesity; particularly adipokines and their implications for chronic inflammation, lipid accumulation, insulin resistance, Endoplasmic Reticulum (ER) stress and angiogenesis. Evidence of molecular signalling pathways that may give rise to the onset and progression of HCC in this context are depicted. Delineation of the pro-inflammatory role of visceral adiposity in liver cancer and its targeting will provide better rational and therapeutic approaches for HCC prevention and elimination. The concept of a central role for metabolism in cancer is the culmination of an effort that began with one of the 20th century's leading biochemists and Nobel laureate of 1931, Otto Warburg.

STAT1, NF-κB and ERKs play a role in the induction of lipocalin-2 expression in adipocytes

Lipocalin-2 (LCN2) is induced in conditions of obesity and Type 2 diabetes (T2DM). IFNγ and TNFα induce LCN2 expression in adipocytes in a manner that is dependent on transcription. The effects of these cytokines are additive. IFNγ induced STAT1 and TNFα induced NF-κB play a role in the induction of LCN2. In the LCN2 promoter, one NF-κB binding site and four STAT1 binding sites were identified by in silico and in vitro approaches. MAPK (ERKs 1 and 2) activation was required for the IFNγ and TNFα induction of LCN2 expression, but did not affect the nuclear translocation or DNA binding activity of STAT1 or NF-κB. The NF-κB binding site and the STAT1 binding sites we identified in vitro were confirmed by in vivo studies. Transfection of a LCN2 promoter/luciferase reporter construct confirmed acute activation by IFNγ and TNFα. Our studies identify mechanisms involved in the actions of cytokines secreted from immune cells in adipose tissue that induce LCN2 expression in conditions of obesity and T2DM.

Extraneuronal activities and regulatory mechanisms of the atypical cyclin-dependent kinase Cdk5

Cyclin-dependent kinase, Cdk5, is an atypical but essential member of the Cdk family of proline-directed serine/threonine kinases with no evident role in cell cycle progression. Cdk5 is present in post-mitotic and terminally differentiated neuronal/glial cells and is also known to arrest cell cycle. Also atypical is the activation of Cdk5 by binding of a non-cyclin activator protein, namely, the Cdk5 regulatory proteins Cdk5R1 (p35), truncated Cdk5R1 (p25), or Cdk5R2 (p39). Despite its ubiquitous presence in all cells and tissues, Cdk5 is often referred to as a neuron-specific kinase largely due to the abundant presence of the activator proteins in neuronal cells. Recently, this concept of a canonical neuronal function of Cdk5 has been extended, if not challenged, by the observation of p35 and p39 expression, as well as Cdk5 activity, in multiple non-neuronal cells. Extraneuronal Cdk5 regulates critical biological processes including transcript-selective translation control for regulation of macrophage gene expression, glucose-inducible insulin secretion, hematopoietic cell differentiation, vascular angiogenesis, cell migration, senescence, and wound-healing, among others. Recent advances in the extraneuronal functions of Cdk5 are reviewed and discussed here in the context of their physiological activities and pathophysiological implications with some speculative comments on the endogenous control mechanisms that might "turn on" Cdk5 activity. The potential importance of targeted inhibition of Cdk5 as therapeutic agents against glucotoxicity, diabetes, cardiovascular diseases, and cancer is also discussed.

Protective Effects of Total Flavonoids from Litsea coreana on Alcoholic Fatty Liver in Rats Associated with Down-Regulation Adipose Differentiation-Related Protein Expression

Alcoholic fatty liver (AFL) is a reversible condition, but it can potentiate the development of alcoholic hepatitis and even cirrhosis by increasing oxidant generation, which is one of the key pathogenic factors and could result in alcoholic liver disease (ALD). Total flavonoids from Litsea coreana (TFLC), an active component extracted from Litsea coreana leve, have been shown to have therapeutic effects on hyperlipidemia. The present study was to evaluate the protective effects of TFLC on alcoholic fatty liver (AFL) in rats, and investigate the potential mechanism. An AFL model in rats was established by intaking different doses of alcohol (concentration from 5% to 40%) over 12 weeks. Serum levels of TG, TC, LDL-C, HDL-C, TNF-α, insulin, and glucose were measured, histopathologic changes were determined, and expression of adipose differentiation-related protein (ADRP) in the liver were evaluated by Western blotting and immunohistochemistry, respectively. The results showed that treatment with TFLC resulted in decreased serum levels of TG, TC, LDL-C, TNF-α, glucose and insulin, as well as improved liver index. Morphological evaluation revealed rats in model group developed a severe steatosis, but the severities of liver steatosis were effectively ameliorated in TFLC (200 and 400 mg/kg) treated groups. Expression of hepatic ADRP were increased in model group, and suppressed in TFLC treated groups. These results suggest that TFLC had a protective effect on AFL rats; the mechanism may be involved in regulation serum lipid profiles via down-regulation of hepatic expression of ADRP in AFL rats.