Sumoylation: Implications for Neurodegenerative Diseases.

The covalent posttranslational modifications of proteins are critical events in signaling cascades that enable cells to efficiently, rapidly and reversibly respond to extracellular stimuli. This is especially important in the CNS where the processes affecting synaptic communication between neurons are highly complex and very tightly regulated. Sumoylation regulates the function and fate of a diverse array of proteins and participates in the complex cell signaling pathways required for cell survival. One of the most complex signaling pathways is synaptic transmission.Correct synaptic function is critical to the working of the brain and its alteration through synaptic plasticity mediates learning, mental disorders and stroke. The investigation of neuronal sumoylation is a new and exciting field and the functional and pathophysiological implications are far-reaching. Sumoylation has already been implicated in a diverse array of neurological disorders. Here we provide an overview of current literature highlighting recent insights into the role of sumoylation in neurodegeneration. In addition we present a brief assessment of drug discovery in the analogous ubiquitin system and extrapolate on the potential for development of novel therapies that might target SUMO-associated mechanisms of neurodegenerative disease.

SUMOylation of Syntaxin1A regulates presynaptic endocytosis.

Neurotransmitter release from the presynaptic terminal is under very precise spatial and temporal control. Following neurotransmitter release, synaptic vesicles are recycled by endocytosis and refilled with neurotransmitter. During the exocytosis event leading to release, SNARE proteins provide most of the mechanical force for membrane fusion. Here, we show one of these proteins, Syntaxin1A, is SUMOylated near its C-terminal transmembrane domain in an activity-dependent manner. Preventing SUMOylation of Syntaxin1A reduces its interaction with other SNARE proteins and disrupts the balance of synaptic vesicle endo/exocytosis, resulting in an increase in endocytosis. These results indicate that SUMOylation regulates the emerging role of Syntaxin1A in vesicle endocytosis, which in turn, modulates neurotransmitter release and synaptic function.

Artemin-GFRα3 interactions partially contribute to acute inflammatory hypersensitivity.

The expression of artemin (ARTN), a glial cell line-derived neurotrophic factor (GDNF) family ligand, increases in pre-clinical models of nociception and recent evidence suggests this growth factor may play a causative role in inflammatory pain mechanisms. The aim of this study was to demonstrate functional inhibition of ARTN with monoclonal antibodies and to determine whether ARTN neutralisation could reverse inflammatory pain in mice. We show that monoclonal antibodies with high affinity to ARTN, completely inhibit ARTN-induced Ret and ERK activation in a human neuroblastoma cell line, and block capsaicin-induced CGRP secretion from primary rat DRG cultures. In addition, administration of anti-ARTN antibodies to mice provides a transient, partial reversal (41%) of FCA-induced mechanical hypersensitivity. Anti-ARTN antibodies had no effect on hypersensitivity in response to partial nerve ligation in mice. These data suggest that ARTN-GFRα3 interactions partially mediate early stage nociceptive signalling following an inflammatory insult.

Combining modelling and mutagenesis studies of synaptic vesicle protein 2A to identify a series of residues involved in racetam binding.

LEV (levetiracetam), an antiepileptic drug which possesses a unique profile in animal models of seizure and epilepsy, has as its unique binding site in brain, SV2A (synaptic vesicle protein 2A). Previous studies have used a chimaeric and site-specific mutagenesis approach to identify three residues in the putative tenth transmembrane helix of SV2A that, when mutated, alter binding of LEV and related racetam derivatives to SV2A. In the present paper, we report a combined modelling and mutagenesis study that successfully identifies another 11 residues in SV2A that appear to be involved in ligand binding. Sequence analysis and modelling of SV2A suggested residues equivalent to critical functional residues of other MFS (major facilitator superfamily) transporters. Alanine scanning of these and other SV2A residues resulted in the identification of residues affecting racetam binding, including Ile273 which differentiated between racetam analogues, when mutated to alanine. Integrating mutagenesis results with docking analysis led to the construction of a mutant in which six SV2A residues were replaced with corresponding SV2B residues. This mutant showed racetam ligand-binding affinity intermediate to the affinities observed for SV2A and SV2B.

Protein SUMOylation in neuropathological conditions.

Small ubiquitin-related modifier (SUMO) proteins are approximately 11 kDa proteins that can be covalently conjugated to lysine residues in defined target proteins. The resultant post-translational modification, SUMOylation, is vital for the viability of mammalian cells and regulates, among other things, a range of essential nuclear processes. It has become increasingly apparent in recent years that SUMOylation also serves multiple functions outside the nucleus and that it plays a critical role in the regulation of neuronal integrity and synaptic function. In particular, dysfunction of the SUMOylation pathway has been implicated in the molecular and cellular dysfunction associated with neurodegenerative and psychiatric disorders. Here, we outline current knowledge of the SUMO pathway and discuss the growing evidence for its involvement in multiple neurodegenerative disorders, with a view to highlighting the potential of the SUMO pathway as a putative drug target.

Addressing volume loss in hand rejuvenation: a report of clinical experience.

BACKGROUND: Current options for treating the aging hand include microdermabrasion, fractional thermolysis, chemical peeling, intense light sources and laser therapy (such as pigment lasers and ablative resurfacing), as well as injectable fillers and volumizers to correct soft tissue atrophy. OBJECTIVE: This article reviews the latest technologies in hand rejuvenation and provides data from three clinical practices using injectable poly-l-lactic acid (PLLA) for soft tissue augmentation. METHODS: Patient data from three clinical practices were retrospectively collected and tabulated. This included baseline patient data, the number of injections and vials of product used, and adverse events. RESULTS: PLLA was used to improve volume loss in the hand to the satisfaction of a majority of patients. The most commonly reported adverse events, such as bruising, swelling and pain, were injection-related and resolved within a few days of treatment. No papules or nodules were reported in any patients and there were no serious adverse events. CONCLUSION: The overall results from the three clinics presented here show that patients were very satisfied with the results of PLLA treatment for the hands, and experienced only minor and short-term injection-related adverse events.

Topical tazarotene in acne vulgaris: treatment approaches.

Topical tazarotene is effective and well tolerated in the treatment of acne vulgaris and has been used successfully in diverse patient populations. However, because factors such as patient skin type and climate may influence its optimal use and frequency of application, treatment approaches often differ according to the populations in which tazarotene is used. The authors review their prescribing practices and special considerations for women, African Americans, patients living in dry climates, adolescents, and Asian Americans.

Effect of adenovirus-mediated overexpression of bovine ADAMTS-4 and human ADAMTS-5 in primary bovine articular chondrocyte pellet culture system.

INTRODUCTION: Articular cartilage matrix synthesis and degradation are dynamic processes that must be balanced for proper maintenance of the tissue. In osteoarthritis (OA), this balance is skewed toward degradation and ultimate loss of matrix. The transcriptional and/or activity levels of hundreds of genes are dysregulated in chondrocytes from osteoarthritic cartilage, and a subset of these genes may represent pivotal factors that could be modulated if their specific role in the disease process could be identified. OBJECTIVE: To investigate the role of ADAMTS-4 and ADAMTS-5 in cartilage matrix degradation by developing a chondrocyte pellet culture assay in combination with adenoviral gene expression, and to demonstrate the utility of this assay by assessing the specific functional contribution of these genes to cartilage matrix metabolism. METHODS: A full-length cDNA for bovine ADAMTS-4 (bADAMTS-4) was isolated, and used to evaluate the expression, regulation, and activity of this gene in bovine cartilage. Adenoviruses expressing bADAMTS-4, human ADAMTS-5 (hADAMTS-5) or human bone morphogenetic protein 2 (BMP-2) were used to infect primary chondrocytes, and their effect on extracellular matrix metabolism was assessed by monitoring the accumulation and release of glycosaminoglycans (GAG) in three-dimensional chondrocyte pellet cultures. RESULTS: Analysis of bADAMTS-4 transcriptional regulation in chondrocytes revealed that interleukin-1alpha (IL-1alpha) was the most potent inducer of bADAMTS-4 mRNA and subsequent aggrecan degradation in cartilage explant cultures of those cytokines tested. bADAMTS-4 mRNA induction by IL-1alpha was greater in nasal cartilage than in articular cartilage. Chondrocytes infected with adenovirus expressing either bADAMTS-4 or hADAMTS-5 genes showed increased aggrecan degradation in newly synthesized matrix by pellet cultures while chondrocytes overexpressing BMP-2 showed increased aggrecan synthesis. CONCLUSION: Adenoviral delivery of genes to primary bovine chondrocytes, followed by culture in three-dimensional pellet format and evaluation of extracellular matrix protein metabolism, is a useful functional assay for assessing the role of genes on cartilage matrix synthesis and degradation.

The antiepileptic drug levetiracetam selectively modifies kindling-induced alterations in gene expression in the temporal lobe of rats.

Gene expression profiling by microarrays is a powerful tool for identification of genes that may encode key proteins involved in molecular mechanisms underlying epileptogenesis. Using the Affymetrix oligonucleotide microarray, we have surveyed the expression levels of more than 26,000 genes and expressed sequence tags (ESTs) in the amygdala-kindling model of temporal lobe epilepsy. Furthermore, the effect of the antiepileptic drug levetiracetam (LEV) on kindling-induced alterations of gene expression was studied. Treatment of rats with LEV during kindling acquisition significantly suppressed kindling development. For gene expression profiling, six groups of rats were included in the present study: (i) and (ii) sham-operated rats treated with saline or LEV; (iii) and (iv) electrode-implanted but non-kindled rats treated with saline or LEV; (v) and (vi) kindled rats treated with saline or LEV. Treatment was terminated after 11 or 12 daily amygdala stimulations, when all vehicle-treated rats had reached kindling criterion, i.e. a stage 5 seizure. Twenty-four hours later, the ipsilateral temporal lobe was dissected for mRNA preparation. Six temporal lobe preparations from each group were analysed for differential gene expression. In control (non-kindled) rats, LEV treatment was devoid of any significant effect on gene expression. In saline-treated kindled rats, a large number of genes were observed to display mRNA expression alterations compared with non-kindled rats. LEV treatment induced marked effects on gene expression from kindled rats. Previously described epilepsy-related genes, such as neuropeptide Y (NPY), thyrotropin-releasing hormone (TRH) and glial fibrillary acidic protein (GFAP) were confirmed to be up-regulated by kindling and partially normalized by LEV treatment. Real-time quantitative polymerase chain reaction confirmed NPY, TRH and GFAP expression data from chip experiments. Furthermore, a number of novel genes were identified from the gene chip experiments. A subgroup of these genes demonstrated correlation between expression changes and kindled phenotype measurements. In summary, this study identified many genes with potentially important roles in epileptogenesis and highlighted several important issues in using the gene chip technology for the study of animal models of CNS disorders.

Compared efficacy and safety of tretinoin 0.1% microsphere gel alone and in combination with benzoyl peroxide 6% cleanser for the treatment of acne vulgaris.

Our purpose was to evaluate the efficacy and safety of a combination of benzoyl peroxide 6% cleanser and tretinoin 0.1% microsphere gel versus monotherapy with tretinoin 0.1% microsphere gel. Eighty-seven healthy males and nonpregnant nonlactating females between the ages of 12 and 30 years with moderate inflammatory acne vulgaris were enrolled in this randomized controlled, investigator-blind, parallel group clinical trial. Subjects were evaluated over 12 weeks for a total of 4 visits. The investigators and subjects completed questionnaires about the test medications. Data from the 56 subjects completing the protocol were considered in the analyses of efficacy and tolerability. The reduction in inflammatory lesions from baseline was significant for both treatment groups at the end of the study. However, there was a significantly greater reduction in the group receiving the combination regimen. Both treatment groups had significant reductions from baseline in noninflammatory lesions at week 12, but no differences were observed between treatment groups. With the exception of skin tightness, which was significantly greater at week 12 in the subjects who received the monotherapy, there were no significant differences between the 2 treatment groups with respect to localized irritation. Adverse events were rare in all subjects. Not only did the combination regimen result in a greater reduction of inflammatory acne lesions than use of the monotherapy but also it did not result in an increase in local irritation.