No abstract

We evaluated the feasibility and safety of therapy with mesenchymal stem cells (MSCs) through consecutively intra-arterial and three repeated intravenous injections and compared the long-term prognosis between MSC-treated (n ¼ 11) and control multiple system atrophy (MSA) patients (n ¼ 18). The MSC-treated patients showed significantly greater improvement on the unified MSA rating scale (UMSARS) than the control patients at all visits throughout the 12-month study period. Orthostasis in UMSARS I items and cerebellar dysfunction-related items of UMSARS II items were significantly different in favor of MSC treatment compared to controls. Serial positron emission tomography scan in the MSC-treated group showed that increased fluorodeoxyglucose uptake from baseline was noted in cerebellum and frontal white matters. No serious adverse effects related to MSC therapy occurred. This study demonstrated that MSC therapy in patients with MSA was safe and delayed the progression of neurological deficits with achievement of functional improvement in the follow-up period.Multiple system atrophy (MSA) is a sporadic, progressive, adult-onset neurodegenerative disorder associated with varying degrees of parkinsonism, autonomic dysfunction, and cerebellar ataxia, characterized pathologically by asynuclein-positive glial cytoplasmic inclusions in brain and spinal cord.

Dyrk is a dual specific protein kinase thought to be involved in normal embryo neurogenesis and brain development. Defects/imperfections in this kinase have been suggested to play an important role in the mental retardation of patients with Down's syndrome. The transcriptional factor cAMP response element-binding protein (CREB) has been implicated in the formation of many types of synaptic plasticity, such as learning and memory. In the present study we show that Dyrk1 activity is markedly induced during the differentiation of immortalized hippocampal progenitor (H19-7) cells. The addition of a neurogenic factor, basic fibroblast growth factor, to the H19-7 cells results in an increased specific binding of Dyrk1 to active CREB. In addition, Dyrk1 directly phosphorylates CREB, leading to the stimulation of subsequent CRE-mediated gene transcription during the neuronal differentiation in H19-7 cells. Blockade of Dyrk1 activation significantly inhibits the neurite outgrowth as well as CREB phosphorylation induced by basic fibroblast growth factor. These findings suggest that Dyrk1 activation and subsequent CREB phosphorylation is important in the neuronal differentiation of central nervous system hippocampal cells.

Lipin1 expression was induced at a late stage of differentiation of 3T3-L1 preadipocytes and maintained at high levels in mature adipocytes. Knockdown of expression of lipin1 by small interfering RNA in 3T3-L1 preadipocytes almost completely inhibited differentiation into adipocytes, whereas overexpression of lipin1 accelerated adipocyte differentiation, demonstrating that lipin1 is required for adipocyte differentiation. In mature adipocytes, transfection of lipin1-small interfering RNA decreased the expression of adipocyte functional genes, indicating the involvement of lipin1 in the maintenance of adipocyte function. Lipin1 increases the transcription-activating function of peroxisome proliferator-activated receptor ␥ 2 (PPAR␥ 2 ) via direct physical interaction, whereas lipin1 did not affect the function of other adipocyte-related transcription factors such as C/EBP␣, liver X-activated receptor ␣, or sterol regulatory element binding protein 1c. In mature adipocytes, lipin1 was specifically recruited to the PPAR␥-response elements of the phosphoenolpyruvate carboxykinase gene, an adipocyte-specific gene. C/EBP␣ up-regulates lipin1 transcription by directly binding to the lipin1 promoter. Based on the existence of a positive feedback loop between C/EBP␣ and PPAR␥ 2 , we propose that lipin1 functions as an amplifier of the network between these factors, resulting in the maintenance of high levels of the specific gene expression that are required for adipogenesis and mature adipocyte functions.Adipose tissue plays an essential role in maintaining metabolic homeostasis (1). White adipose tissue takes up fatty acids derived from the diet or the liver as well as increases the uptake of glucose in response to insulin by recruiting glucose transporter 4 (GLUT4) 2 to the plasma membrane. Then white adipose tissue stores the glucose or fatty acids as a form of triacylglyceride and releases free fatty acids during states of starvation. Recent studies have shown that adipose tissue secretes various humoral factors called adipocytokines which play numerous functions associated with food intake, insulin sensitivity, energy homeostasis, inflammatory responses, and atherogenesis (2). In obese subjects adipocytes cannot function adequately, thereby causing various metabolic syndromes including insulin resistance, dyslipidemia, and coronary-vascular disease (3-6). Lipodystrophy leads to the same condition as obesity due to lack of adipocyte function (7-9). Thus, studying the molecular mechanisms that control adipose tissue development and function is important for understanding the pathophysiology of metabolic syndromes.Adipogenesis is a process in which premature cells acquire adipocyte-specific functions. A complex network of transcription factors is developed during this process in response to extracellular adipogenic stimuli. In 3T3-L1 preadipocyte cells the CCAAT/enhancer-binding proteins ␤ and ␦ (C/EBP␤ and C/EBP␦) are induced immediately upon adipogenic hormonal stimuli, and they are expressed for approximately 2 days ...

Most individuals with Down syndrome show early onset of Alzheimer disease (AD), resulting from the extra copy of chromosome 21. Located on this chromosome is a gene that encodes the dual specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A). One of the pathological hallmarks in AD is the presence of neurofibrillary tangles (NFTs), which are insoluble deposits that consist of abnormally hyperphosphorylated Tau. Previously it was reported that Tau at the Thr-212 residue was phosphorylated by Dyrk1A in vitro. To determine the physiological significance of this phosphorylation, an analysis was made of the amount of phospho-Thr-212-Tau (pT212) in the brains of transgenic mice that overexpress the human DYRK1A protein (DYRK1A TG mice) that we recently generated. A significant increase in the amount of pT212 was found in the brains of DYRK1A transgenic mice when compared with age-matched littermate controls. We further examined whether Dyrk1A phosphorylates other Tau residues that are implicated in NFTs. We found that Dyrk1A also phosphorylates Tau at Ser-202 and Ser-404 in vitro. Phosphorylation by Dyrk1A strongly inhibited the ability of Tau to promote microtubule assembly. Following this, using mammalian cells and DYRK1A TG mouse brains, it was demonstrated that the amounts of phospho-Ser-202-Tau and phospho-Ser-404-Tau are enhanced when DYRK1A amounts are high. These results provide the first in vivo evidence for a physiological role of DYRK1A in the hyperphosphorylation of Tau and suggest that the extra copy of the DYRK1A gene contributes to the early onset of AD. Down syndrome (DS)3 is the most common genetic disorder with a frequency of 1 in 800 live births, and it is caused by the presence of an extra copy of whole or part of human chromosome 21 (1, 2). DS patients suffer various symptoms, including congenital heart defects, immune and endocrine system defects, mental retardation, and early onset of Alzheimer disease (AD) (3). Both DS and AD patients have pathological hallmarks, amyloid plaques and neurofibrillary tangles (NFTs) that are insoluble deposits made of proteins called ␤-amyloid (A␤) and hyperphosphorylated Tau, respectively (4 -6). Although an early onset AD in DS patients is not clearly understood, one potential mechanism is the presence of three chromosomal copies of ␤-amyloid precursor protein (APP) gene. However, the APP overexpression alone in mice does not show the endosome abnormalities observed in AD-like pathology (7), implying the necessity of additional genes on the chromosome 21 for a full spectrum of AD pathologies.NFTs found in AD are composed of paired helical filaments (PHFs), which are mainly composed of hyperphosphorylated Tau protein (8). To date, more than 30 phosphorylation sites and 7-10 mol of phosphates per mol of Tau have been observed in PHF-Tau (9, 10). Although Tau protein is phosphorylated in vitro by numerous kinases, it is unclear how many kinases actually phosphorylate Tau in vivo. Currently, only glycogen synthase kinase 3␤ (GSK3␤), cyclin-dependent kinas...

Metabotropic glutamate receptors (mGluRs) 1-8 are G proteincoupled receptors (GPCRs) that modulate excitatory neurotransmission, neurotransmitter release, and synaptic plasticity. PKC regulates many aspects of mGluR function, including protein-protein interactions, Ca 2؉ signaling, and receptor desensitization. However, the mechanisms by which PKC regulates mGluR function are poorly understood. We have now identified calmodulin (CaM) as a dynamic regulator of mGluR5 trafficking. We show that the major PKC phosphorylation site on the intracellular C terminus of mGluR5 is serine 901 (S901), and phosphorylation of this residue is up-regulated in response to both receptor and PKC activation. In addition, S901 phosphorylation inhibits mGluR5 binding to CaM, decreasing mGluR5 surface expression. Furthermore, blocking PKC phosphorylation of mGluR5 on S901 dramatically affects mGluR5 signaling by prolonging Ca 2؉ oscillations. Thus, our data demonstrate that mGluR5 activation triggers phosphorylation of S901, thereby directly linking PKC phosphorylation, CaM binding, receptor trafficking, and downstream signaling.phosphorylation ͉ protein kinase C ͉ receptor trafficking T he group I metabotropic glutamate receptor mGluR5 is highly expressed in the forebrain, where it regulates synaptic plasticity (1, 2). In addition, mGluR5 plays a role in pain (3) and addiction (4) and in neurological disorders such as fragile X syndrome (5, 6). Group I mGluRs are G protein-coupled receptors (GPCRs), which are coupled to phospholipase C, and receptor activation triggers phosphoinositide turnover, release of intracellular Ca 2ϩ , and activation of Protein Kinase C (PKC) (7). Although PKC activity regulates mGluR5-mediated Ca 2ϩ signaling and receptor function (8-11), there are no studies linking PKC phosphorylation of mGluR5 to receptor surface expression, endocytosis, or intracellular trafficking.Like other GPCRs, mGluR5 interacts with many proteins in addition to the guanine nucleotide-binding proteins (G proteins). Most of the binding sites for these protein-protein interactions reside within the long intracellular C-terminal domain of mGluR5, suggesting that this region is critical in the functional regulation of mGluR5. For example, the Homer proteins bind to the PPxxFR motif within the distal C terminus, the Tamalin protein associates with the distal C terminus, and calmodulin (CaM) and the E3 ligase Siah-1A bind to the first one-third of the mGluR5 C terminus (12-15). However, the dynamic regulation of these protein-protein interactions has not been described. CaM is a particularly intriguing candidate as an mGluR5 regulator because of its Ca 2ϩ dependence and its key role in synaptic plasticity (16,17). Furthermore, CaM binding to other GPCRs, including dopamine, opioid, and serotonin receptors, has been documented, consistent with a conserved regulatory role for CaM in regulating . We now show that PKC phosphorylation of serine 901 (S901) on mGluR5 inhibits CaM binding and decreases mGluR5 surface expression. Furthermore, preve...

GLUT2 is mainly expressed in the liver, ␤-cells of the pancreas, and the basolateral membrane of kidney proximal tubules and plays an important role in glucose homeostasis in living organisms. The transcription of the GLUT2 gene is known to be upregulated in the liver during postprandial hyperglycemic states or in type 2 diabetes. However, a molecular mechanism by which glucose activates GLUT2 gene expression is not known. In this study, we report evidence that sterol response element-binding protein (

Recent studies have provided evidence that Zn 21 plays a crucial role in ischemia-and seizure-induced neuronal death. However, the intracellular signaling pathways involved in Zn 21-induced cell death are largely unknown. In the present study, we investigated the roles of mitogen-activated protein kinases (MAPKs), such as c-Jun N-terminal kinase (JNK), p38 MAPK and extracellular signal-regulated kinase (ERK), and of reactive oxygen species (ROS)