Neurofilament functions in health and disease.

Transgenic approaches have recently been used to investigate the functions of neuronal intermediate filaments. Gene knockout studies have demonstrated that neurofilaments are not required for axogenesis and that individual neurofilament proteins play distinct roles in filament assembly and in the radial growth of axons. The involvement of neurofilaments in disease is supported by the discovery of novel mutations in the neurofilament heavy gene from cases of amyotrophic lateral sclerosis and by reports of neuronal death in mouse models expressing neurofilament and alpha-internexin transgenes. However, mouse studies have shown that axonal neurofilaments are not required for pathogenesis caused by mutations in superoxide dismutase and that increasing perikaryal levels of neurofilament proteins may even confer protection in this disease.     

Immune regulatory functions of DOCK family proteins in health and disease

DOCK proteins constitute a family of evolutionarily conserved guanine nucleotide exchange factors (GEFs) for Rho family of GTPases. Although DOCK family proteins do not contain the Dbl homology domain typically found in GEFs, they mediate the GTP–GDP exchange reaction through DHR-2 domain. Accumulating evidence indicates that the DOCK proteins act as major GEFs in varied biological settings. For example, DOCK2, which is predominantly expressed in hematopoietic cells, regulates migration and activation of leukocytes through Rac activation. On the other hand, it was recently reported that mutations of DOCK8, another member of the DOCK family proteins, cause a combined immunodeficiency syndrome in humans. This article reviews the structure, functions and signaling of DOCK2 and DOCK8, especially focusing on their roles in immune responses.     

Sirtuin chemical mechanisms

Sirtuins are ancient proteins widely distributed in all lifeforms of earth. These proteins are universally able to bind NAD⁺, and activate it to effect ADP-ribosylation of cellular nucleophiles. The most commonly observed sirtuin reaction is the ADP-ribosylation of acetyllysine, which leads to NAD⁺-dependent deacetylation. Other types of ADP-ribosylation have also been observed, including protein ADP-ribosylation, NAD⁺ solvolysis and ADP-ribosyltransfer to 5,6-dimethylbenzimidazole, a reaction involved in eubacterial cobalamin biosynthesis. This review broadly surveys the chemistries and chemical mechanisms of these enzymes.     

Sirtuin regulation in calorie restriction

The beneficial effects of calorie restriction diet in extending lifespan and preventing diseases have long been recognized. Recent genetic and molecular studies in model organisms began to uncover the molecular regulation of calorie restriction response, with the gene SIR2 playing an essential role. This article summarizes the latest development on how mammalian SIR2 homologs coordinately regulate the calorie restriction response.     

Structural Basis for Sirtuin Activity and Inhibition

Sir2 proteins, or sirtuins, are a family of enzymes that catalyze NAD⁺-dependent deacetylation reactions and can also process ribosyltransferase, demalonylase, and desuccinylase activities. More than 40 crystal structures of sirtuins have been determined, alone or in various liganded forms. These high-resolution architectural details lay the foundation for understanding the molecular mechanisms of catalysis, regulation, substrate specificity, and inhibition of sirtuins. In this minireview, we summarize these structural features and discuss their implications for understanding sirtuin function.     

Nuclear lamin functions and disease

Recent studies have shown that premature cellular senescence and normal organ development and function depend on the type V intermediate filament proteins, the lamins, which are major structural proteins of the nucleus. This review presents an up-to-date summary of the literature describing new findings on lamin functions in various cellular processes and emphasizes the relationship between the lamins and devastating diseases ranging from premature aging to cancer. Recent insights into the structure and function of the A- and B- type lamins in normal cells and their dysfunctions in diseased cells are providing novel targets for the development of new diagnostic procedures and disease intervention. We summarize these recent findings, focusing on data from mice and humans, and highlight the expanding knowledge of these proteins in both healthy and diseased cells.     

Cytokines in health and disease

Cytokines are cellular regulators of non-immunoglobulin character. The studies of interferon, a representative cytokine, support the view that cytokines are information molecules forming a network in the animal organism. Their main task is to protect the homeostasis of the organism. This may be disturbed both by external and internal causes. The results of the studies of interferon appearing in patients with systems lupus erythematosus do not support the assumption that interferons of this type may play a role in aetiology of autoimmune diseases.     

Oxytocin in health and disease

Oxytocin is a nonapeptide of the neurohypophyseal protein family that binds specifically to the oxytocin receptor to produce a multitude of central and peripheral physiological responses. Within the central nervous system oxytocin is expressed by the neurons of the hypothalamus that project into higher brain centres and the posterior pituitary gland, from where it enters the circulation by release into the portal capillaries. Centrally, it modulates, maternal, sexual, social and stress related behaviour. Peripheral actions of oxytocin are commonly associated with smooth muscle contraction, particularly within the female and male reproductive tracts. Local synthesis of oxytocin along with its receptor in these regions indicates the presence of local oxytocinergic systems. More sinister implications for oxytocin in autism, depression and several cancers have recently been identified. A greater understanding of the role of oxytocinergic mechanisms will determine the potential for targeting this regulatory peptide in the pharmacological management of these disorders.     

Magnesium in health and disease

Introduction

Magnesium is an essential electrolyte in living organisms, which has to be supplied daily in a sufficient amount.

Methods

The clinical importance of a magnesium overload or a magnesium intoxication is seldom. However, a magnesium deficiency is of special importance in humans, despite of a normal magnesium supplementation. The primary effect of a magnesium deficiency results in a reduction of energy production. This reduced energy production can result in a disturbed membrane function, calcium magnesium antagonism and cell dysfunction.

Results

Thereby consequences may result in an organ dysfunction and an altered answer to external and internal stress. The reduced energy status is responsible for the recovery of unhealthy individuals - e.g. cardiac arrhythmias, primary hypertension, pre-eclampsia, cramps, allergic reactions—upon repletion of Mg status.

Conclusions

The importance of an oral or intravenously supplementation of magnesium has often been described in a variety of diseases. In addition of special interest is the use of magnesium in critically ill patients in intensive care medicine.     

Leukotrienes in health and disease

The leukotrienes (LTs) are 5-lipoxygenase metabolites of arachidonic acid. The synthesis and release of LTs have been demonstrated in many cells and organs, and LTs are considered to be normal products of continuous metabolism of arachidonic acid. However, although evidence in favor of a critical role for LTs in regulation of physiological functions is still scarce, a growing body of evidence suggests a role for LTs in mediation of several pathophysiological processes such as generalized or local immune reactions, inflammation, asthma, shock, and trauma. LTs have been shown to have potent actions on many essential organs and systems, including the cardiovascular system (heart, blood vessels, microcirculation), the pulmonary system (lung, airways), the central nervous system (neural, glial, and vascular elements), the gastrointestinal tract, and the immune system. In these organs the effects of LTs are mediated by specific LT receptors. Identification of LTs and characterization of their regional and systemic pathological effects, together with characterization of their receptors and elucidation of their structure-activity relationships, are fundamental to developing LT antagonists or synthesis inhibitors that might prevent or reverse LT-dependent reactions. Preliminary reports have already shown that such pharmacological agents ameliorate some aspects of disease processes in experimental animals as well as in humans. In this brief review we intend to highlight the evidence that implicates LTs in normal physiological functions as well as in disease processes.     

Angiogenesis in health and disease

Blood vessels constitute the first organ in the embryo and form the largest network in our body but, sadly, are also often deadly. When dysregulated, the formation of new blood vessels contributes to numerous malignant, ischemic, inflammatory, infectious and immune disorders. Molecular insights into these processes are being generated at a rapidly increasing pace, offering new therapeutic opportunities that are currently being evaluated.