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Mast cells play an important role in diverse physiological mechanisms as well as taking part in antimicrobial defense. What is more, these cells are important regulators of a number of pathophysiological processes, involving allergic reactions. Therefore, it seems to be very important to know and understand the factors and receptors influencing mast cell activity. Nowadays it is well established that activating signals are counterbalanced by negative or inhibition signals transmitted by inhibitory receptors containing immunoreceptor tyrosine-based inhibitory motifs (ITIMs). Inhibitory receptor engagement leads to ITIM tyrosine phosphorylation, the recruitment and activation of protein tyrosine phosphatases such as SHP-1, SHP-2 and/or SHIP, and the dephosphorylation of activating receptor associated proteins. There is growing evidence that a number of inhibitory receptors have been identified on mast cells. The scope of this paper is to present the current knowledge on mast cell-associated inhibitory receptors, such as FcgRIIB, paired immunoglobulin- like receptor B (PIR-B), CD300, CD172a, gp49B1, CD200R, sialic acid-binding immunoglobulin- like lectin (Siglec) molecules, CD305, allergin-1, mast cell function-associated antigen (MAFA), and CD72. The role of these inhibitory receptors in regulation mast cell activity is also discussed. [ABSTRACT FROM AUTHOR]

Phosphorylation and dephosphorylation play a fundamental role in most signaling pathways, as these processes can directly regulate various aspects of protein function. It is estimated that there are about 100,000 potential phosphorylation sites in proteins encoded by the human genome and about 30-50% of all proteins in the cell can be phosphorylated, which is directly related to the functions they perform. To determine whether a given protein is phosphorylated, any changes in its mobility caused by this modification are examined during PAGE electrophoresis. Concurrently, tandem mass spectrometry (MS/MS) allows to identify specific phosphorylation sites. The next step involves the prediction (using in silico analysis) which kinases can phosphorylate a specific site in the given protein. Then, in order to verify the information obtained from databases, in vitro and/or in vivo experiments are carried out.

Increased consumption of highly processed food and low level of physical activity are the main culprits of the obesity epidemic. Excessive visceral fat is an independent risk factor for insulin resistance. Pathogenesis of insulin resistance includes increased oxidation of free fatty acids and chronic inflammation. It seems that a recently discovered adipokine - omentin can play a role in the complex phenomenon of insulin resistance. Studies have shown that the concentrations of omentin are reduced in conditions associated with insulin resistance, such as obesity, polycystic ovary syndrome, type 2 diabetes and gestational diabetes amongst others. Available research also indicate a positive correlation between plasma adiponectin and omentin. Biological functions of omentin and its mechanism of action are not fully understood. It has been determined that omentin enhances insulin-stimulated glucose uptake in subcutaneous and visceral adipose tissue. However, this adipokine does not stimulate basal glucose transport. It has been shown that omentin increases phosphorylation of AMP-activated protein kinase, which indicates a potential role of omentin in energy homeostasis., (© 2015 MEDPRESS.)

The transcription factor Nrf2 controls the expression of genes encoding cytoprotective enzymes and proteins. Its activation is related to conformational changes in the inhibitory protein Keap1 and/or Nrf2 phosphorylation by upstream kinases. Activation of Nrf2 can lead to the induction of phase II enzymes responsible for the inactivation of potential carcinogens. This may constitute an important strategy of chemoprevention. Moreover, these enzymatic systems participating in the biotransformation of drugs can reduce their therapeutic effects, contributing to drug resistance. For this reason, a clear understanding of the role of Nrf2 is essential to assess the beneficial and adverse effects of its up-regulation, particularly in relation to the prevention and treatment of cancer. This article summarizes the current state of knowledge on the significance of Nrf2 in tumorigenesis.

Skeletal muscle insulin resistance manifests as a decreased ability of insulin to stimulate glucose uptake in consequence of an impairment in its intracellular signaling. Sirtuin 1 (SIRT1), which belongs to the family of sirtuins (Sir2; silent information regulator 2 protein) participates in the regulation of skeletal muscle glucose and lipid metabolism. Experimental studies indicate that SIRT1 may play a role in the pathogenesis of skeletal muscle insulin resistance. SIRT1 directly influences insulin signal transduction pathway. It increases insulin-dependent IRS2 phosphorylation and Akt activation. Moreover, SIRT1 interacts with PGC1α and AMPK to stimulate muscle glucose uptake and fatty acid oxidation and thus it can prevent insulin resistance. SIRT1 activators might be useful in the treatment of insulin resistance-related diseases.

The Hippo pathway (also known as SWH--Salvador/Warts/Hippo), discovered for the first time in Drosophila melanogaster, is responsible for cell proliferation and organ size control in mammalian systems. The components of the pathway are two kinases and their adaptor proteins which inhibit the transcription co-activator YAP by phosphorylation. When the pathway is inactive (as an effect of upstream component gene expression disorders), activated YAP is translocated to the nucleus where it cooperates with TEAD transcription factor and promotes expression of genes that regulate cell proliferation and apoptosis. YAP acts generally as an oncogene, although there are some reports describing its role as a tumor suppressor. Since all of the core components are well known, the latest reports provide mostly information about upstream components of the Hippo pathway or its interaction with other biochemical pathways. Because of the Hippo pathway's role in the cell cycle, it has become a very attractive object for studies of the genetic background of cancer. The under- or overexpression of genes involved in the Hippo pathway has been described in many different types of cancers. Moreover, it has been shown that there is a strong connection between cancer cell phenotype and highly activated YAP presence in the nucleus. This paper reviews the most important data about Hippo pathway regulation in Drosophila and mammals, including its numerous disorders and their implications for cell function.

The commitment of myogenic cells in skeletal muscle differentiation requires earlier irreversible interruption of the cell cycle. At the molecular level, several key regulators of the cell cycle have been identified: cyclin-dependent kinases and their cyclins stimulate the cell cycle progress and its arrest is determined by the activity of cdk inhibitors (Cip/Kip and INK protein families) and pocket protein family: Rb, p107 and p130. The biological activity of cyclin/cdk complexes allows the successive phases of the cell cycle to occur. Myoblast specialization, differentiation and fusion require the activity of myogenic regulatory factors, which include MyoD, myogenin, Myf5 and MRF4. MyoD and Myf5 play a role in muscle cell specialization, myogenin controls the differentiation process, whereas MRF4 is involved in myotube maturation. The deregulation of the cell cycle leads to uncontrolled proliferation, which antagonizes the functions of myogenic factors and it explains the lack of differentiation-specific gene expression in dividing cells. Conversely, the myogenic factor MyoD seems to cooperate with cell cycle inhibitors leading to inhibition of cell cycle progress and commitment to the differentiation process. The hypophosphorylated form of Rb and cdk inhibitors play an important role in permanent arrest of the cell cycle in differentiated myotubes. Furthermore, cyclin/cdk complexes not only regulate cell division by phosphorylation of several substrates, but may also control other cellular processes such as signal transduction, differentiation and apoptosis. Beyond regulating the cell cycle, Cip/Kip proteins play an important role in cell death, transcription regulation, cell fate determination, cell migration and cytoskeletal dynamics. The article summarizes current knowledge concerning the interactions of intracellular signaling pathways controlling crucial stages of fetal and regenerative myogenesis.

O- and N-glycosylation are the most common and complex of the post-translational modifications. Both are enzymatic processes and it was suggested that both could be regulated by cAMP cascade at the early stages. N-glycosylation starts with the formation of lipid-linked oligosaccharides and this process is catalysed by crucial glycosyltransferase - dolichol phosphate mannose synthase. The results of several studies strongly suggest that the cAMP acting through a cAMP-dependent protein kinase A-mediated protein phosphorylation/dephosphorylation cycle may modulate activation of this enzyme. It was shown that cAMP can also up regulate another enzyme involved in phosphodolichole synthesis - cis-prenyltransferase. The mechanism acting here is the alteration of the rate of its gene expression. cAMP cascade is also involved in regulation of O-glycosylation since phosphorylation of human glutamine:fructose-6-phosphate amidotransferase results in depletion of O-GlcNAc structure formation. These observation suggested an important role of GPCRs and their ligand in regulation of N- and O-glycan synthesis.

PDE3 is a dual-substrate phosphodiesterase responsible for hydrolyzing both cAMP and cGMP whilst being simultaneously inhibited by cGMP. This feature is related to presence of the 44 amino acid insert in the catalytic domain, which determines the mechanism of introduction of the cyclic nucleotide into the catalytic pocket of the enzyme. Once bound in the catalytic site cGMP results in steric hindrance for cAMP to enter the site. The regulatory domain of PDE3 consists of two hydrophobic regions: NHR1 and NHR2. Their presence defines the enzyme's intracellular localization, thus determining its participation in particular signaling cascades. Due to the properties of PDE3 this enzyme has exceptional importance for the cross-talk between cAMP-dependent signaling and other cascades. There are two different mechanisms of action of PDE3 enzymes in cell signaling pathways. In many signaling cascades assembly of a signalosome is necessary for phosphorylation and activation of the PDE3 proteins. In response to certain hormones and growth factors, PDE3 merges the metabolism of cAMP with protein kinase-dependent signaling pathways. PDE3 also controls the level of cAMP with regard to the alternating concentration of cGMP. This effect occurs in signaling cascades activated by natriuretic peptide.

Ezrin, radixin and moesin, forming the ERM protein family, act as molecular crosslinkers between actin filaments and proteins anchored in the cell membrane. By participating in a complex intracellular network of signal transduction pathways, ERM proteins play a key role in the regulation of adhesion and polarity of normal cells through interactions with membrane molecules, e.g. E-cadherin. Dynamic cytoskeletal transformations, in which the ERM and Rho GTPases are involved, lead to the formation of membrane-cytoplasmic structures, such as filopodia and lamellipodia, which are responsible for cellular motility. The interactions of ERM proteins with active Akt kinase cause the acquisition of antiapoptotic cellular features by downregulation of the proapoptotic protein Bad. ERM protein activity is regulated by phosphorylation/dephosphorylation reactions and linking phosphatidylinositols. The model of activation based on the molecular conformation changes by breaking the intramolecular bonds and exposing actin binding sites is essential for the proper functioning of the ERM proteins. Additionally, the connection types between the ERM and membrane proteins (direct or indirect by EBP50 and E3KARP) play an important role in transduction of signals from the extracellular matrix. Due to the wide range of ezrin, radixin and moesin cytophysiological features, detailed exploration of the ERM biochemistry will provide a series of answers to questions about ambiguous functions in many intracellular signal transduction pathways.

The article presents the melanogenesis pathway and the role of cyclic adenosine monophosphate (cAMP) and microphthalmia transcription factor (MITF) in regulation of this process. Products of melanogenesis are eu- and/or pheomelanins synthesized in a multistage process of tyrosine oxidation and polymerization. The conversions require the presence of tyrosinase (TYR, key enzyme), tyrosine hydroxylase isoform I (THI) and tyrosinase related proteins (TRP1 and TRP2). Many types of signal molecules and transcription factors participate in regulation of melanin synthesis, but the most important are cAMP and MITF. cAMP is the second messenger in the intracellular signal cascade, which is synthesized from adenosine triphosphate (ATP) by adenylyl cyclase, activated among others by the melanocortin receptor and the αS subunit of G protein. The signal molecule cAMP regulates MITF, TYR, THI, GTP-cyclohydroxylase I (GTP-CHI) transcription and phenylalanine hydroxylase (PAH) phosphorylation at Ser16 by protein kinase A (PKA). Mutations of genes encoding proteins belonging to the cAMP signal cascade may lead to McCune-Albright and Carney syndromes. MITF is one of the most important nuclear transcription factors regulating melanogenesis. Currently 10 isoforms of human MITF are known, but in melanocytes only MITF-M, MITF-Mdel, MITF-A and MITF-H occur. MITF transcription factor regulates melanogenesis by activation of tyrosinase, TRP1 and TRP2 transcription. It also affects expression of other factors regulating melanosome maturation, biogenesis and transport. Moreover, it regulates melanocyte proliferation and protection against apoptosis. Mutations of the MITF gene may lead to hereditary diseases: Waardenburg type II and Tietz syndromes.

The scientific literature is rich in reports concerning the participation of MAP kinases in various aspects of the physiology of different organisms. There are, however few papers devoted to the evolution of these pathways. This paper offers a survey of the scientific literature describing how MAP kinase pathways have evolved. Why is the cascade of protein phosphorylation on serine, threonine and tyrosine residues more advantageous in Eucaryota than the two-component regulatory system, based on the phosphorylation of histidine and aspartic acid, which predominates in bacteria? How were these pathways formed and evolved? Finally, how important role do they play in the physiology of human organism? Disturbances in the proper functioning of the MAP kinase pathways lead to uncontrolled cell proliferation and the emergence of various diseases including cancer. Because the average life span has lenghtened we hear more and more often about neurodegenerative diseases that lead to dementia or paralysis. Disturbances in the proper functioning of the MAP kinase pathways in neurodegenerative diseases have also been reported recently. Therefore, in this paper I present the current state of research on the dysfunction of these pathways in three diseases: Alzheimer's, Parkinson's and amyotrophic lateral sclerosis (ALS).

Phospholipase C is an enzyme which catalyzes the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P(2)) into second messengers inositol-1,4,5-triphosphate (Ins(1,4,5)P3) and diacylglycerol (DAG). These messengers then promote the activation of protein kinase C and release of Ca(2+) from intracellular stores, initiating numerous cellular events including proliferation, differentiation, signal transduction, endocytosis, cytoskeletal reorganization or activation of ion channels. There have been identified 14 isozymes of PLC among which PLCγ1 and PLCγ2 are of particular interest. PLCγ contains catalytic region XY and a few regulatory domains: PH, EF and C2. The most unique features of these two enzymes are the Src homology domains (SH2, SH3) and split PH domain within the catalytic barrel. PLCγ1 and PLCγ2 have an identical domain structure, but they differ in their function and occurrence. Phospholipase Cγ1 is expressed ubiquitously, especially in the brain, thymus and lungs. PLCγ1 can be activated by receptor tyrosine kinases (i.e.: PDGFR, EGFR, FGFR, Trk), as well as non-receptor protein kinases (Src, Syk, Tec) or phosphatidic acid, tau protein and its analogue. The molecular mechanism of PLCγ1 activation includes membrane recruitment, phosphorylation, rearrangements and activation in the presence of growth factors. In reference to PLCγ1 regulation, a number of positive and negative modulators have been considered. The most important positive modulator is phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P(2)). Protein kinase A and C, tyrosine phosphatases (SHP-1, PTP-1B) and Cbl, Grb2, Jak2/PTP-1B complex proteins have been described as negative regulators of PLCγ1 activation.

The p66Shc adaptor protein has been in the spotlight of many researchgroups around the world for over adecade. Experiments conducted inrecent years unraveled its structure and enabled the recognition of basic cellular functions. Despite an undoubtedly tremendous progress in the characterization of p66Shc, mechanisms through which this protein potentially impacts the metabolism of mitochondria, and thus the cellular energetics are still waiting to be elucidated. Particularly interesting and profoundly studied is the concept that p66Shc may be a key component of the cell response to oxidative stress which may effectively contribute to the lifespan of the organism. p66Shc phosphorylation at serine 36 triggers a cascade of events leading to an increase in reactive oxygen species (ROS) production. The widely accepted free radical theory of ageing, proposed by Harman inthe - 1950s, assumes that an uncontrolled increase of ROS may lead to oxidation of fundamental cellular components such as proteins and phospholipids even sometimes premature dand cause DNA damage. Accumulation of such lesions in cells may unfavorably affect the functions of tissues and organs, leading to pathologies oreath of the organism. Although well experimentally established, knowledge regarding the involvement of the p66Shc protein in the production of ROS and its impact on the lifespan of organisms remains insufficient and requires a lot of additional research. Further investigation will permit a better understanding ofthe mechanisms governing the processes o f aging andthe emergence of variouspathologies associated with oxidative stress. This work is an attempt to systematize the existing knowledge about the p66Shc protein structure and functions. Another objective was to draw attention to the most interesting aspects and results of in vivo and in vitro studies in different models in the context of oxidative stress-associated pathologies and in aging.

Nrf2 transcription factor plays a crucial role in protection of cells against oxidative stress. Under normal conditions Nrf2 is sequestered in cytoplasm by a cytoskeletal protein, Keapl. Situation is changed under stressful conditions,when electrophiles and/or reactiveoxygen species (ROS) cause dissociation of Nrf2 from Keap1. As a consequence, Nrf2 is translocated to the nucleus, that leads to activation of cytoprotective genes involved in electrophile conjugation, excretion of xenobiotics, ROS scavenging and stabilization of cellular redox potential. Amongst xenobiotics, there are many mutagenic and cancerogenic factors. Phase I and II enzymes are responsible for inactivation and removal of such compounds. It has been shown that induction of phase II enzymes confers protection upon insult by reactive metabolites of cancerogens or ROS. Since Nrf2 is an inductor of those enzymes it can be considered as a potential target for cancer chemoprevention. Similarly, in case of neurodegenerative disorders, which pathogenesis is connected to oxidative stress, Nrf2 may be important for therapeutical and preventive strategies

Double-strand breaks (DSBs) are highly deleterious DNA lesions because they can lead to chromosome aberrations or apoptosis. Various physical, chemical, and biological factors are involved in DSB induction. The formation of nuclear DSBs triggers phosphorylation of H2AX at Ser139; phosphorylated H2AX is named gamma H2AX. It is believed that histone H2AX phosphorylation is required for the concentration of DNA repair proteins to the damaged chromatin. H2AX is phosphorylated by members of phosphoinositide 3-kinase-related protein kinases (PIKKs), such as ATM (ataxia teleangiectasia mutated), which is the main mediator of H2AX phosphorylation in response to DSB induction. The development of immunocytochemical methods of gamma H2AX detection provided a convenient tool for research and is considered a gold standard for DSB analysis. These methods are sensitive and specific in the detection of a single DSB. Assessment of H2AX phosphorylation can be used in clinical practice as a marker of premalignant lesions and to predict cell sensitivity to radiotherapy and chemotherapy.

Mitochondria, besides playing a central role in energy metabolism within the cell, are involved in a cohort of other processes like cellular differentiation and apoptosis. Investigations during recent few years have shown that protein kinases, including PKA, PKB/Akt, PKC, Raf-1, p38 MAPK, JNK, ERK1/2, Src, Fyn and Csk, may directly interact with mitochondrial proteins. Their role mainly concentrates at phosphorylation of pro- and anti-apoptotic proteins (Bad, Bax, Bcl-2, Bcl-xL), phosphorylation/modification of electron transport chain proteins (complex I, COIV), MPTP forming proteins VDAC and ANT, proteins of mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) and phospholipid scramblase 3 (PLSCR3). Many experimental data showed the presence of protein kinases in the outer and inner mitochondrial membranes as well as in the mitochondrial matrix during in vitro cell stimulations, in neurodegenerative diseases and in in vivo ischaemia heart preconditioning. These data show that translocation of protein kinases to mitochondria plays an important role especially during ischaemia/reperfusion in brain and heart.

Focal adhesion kinase (FAK) is a 125-kDa cytoplasmic tyrosine kinase located in cells which create attachments with the extracellular matrix (ECM) or with other cells. The primary function of FAK is to transmit the signal coming from the integrine receptor, participating in adhesion, to the intracellular protein cascade. The FAK kinase transducing the signal indirectly plays a crucial role in many cellular processes. This protein is engaged in cell cycle regulation, adhesion, migration, invasion and metastasis, cytoskeleton protein phosphorylation, and apoptosis. Deregulation of the FAK-dependent processes, e.g. adhesion, growth, viability, and cell mobility, is a significant element of cancer progression. FAK protein level expression is varies widely and depends on the development grade of the cancer. A minor FAK overexpression is already observed in the preinvasion grade, increasing significantly in the invasive state. The high FAK expression correlates with cancer cell migration, invasion, and ability for metastasis. The evaluation of FAK expression in cancer cells might become an important prognostic factor, since FAK expression studies provide important information that provides the opportunity to identify the cancer grade.

Introduction: p53 protein is a critical regulator of cell cycle and apoptosis. Many stimuli change its expression and modify its functions. The aim of our work was to determine stability and chosen posttranslational modification of p53 protein during the treatment of lung cancer., Material and Methods: We investigated levels of poly-ADP-ribose- a marker of cellular DNA damage, DNA ploidy, Ki-67 expression, wild type and mutated p53 protein expression and intensity of phosphorylation of chosen p53 serine sites: C-terminal Ser392, and N-terminal Ser15, and Ser20 in fiberoptic bronchoscopy biopsy samples taken from patients suffering from recurrent squamous cell lung cancer before and after radio/chemotherapy. Analysis was based on results obtained from 23 patients after surgery in I-IIIA clinical stage of the disease., Results: Therapy lowered the number of G2/M cells, but increased S fraction cell population in about 50%. Therapy increased p53 expression and p53 phosphorylation at Ser392 and Ser20, and these changes correlated with poly-ADP-ribose levels and Ki-67 expression., Conclusions: Our results indicate that apart from changes in p53 quantity, p53 posttranslational phosphorylation play a role in regulation of neoplastic cells proliferation in response to drugs.

Membrane intrinsic proteins (MIPs) are a diverse class of integral membrane proteins that mediate the bi-directional flux of water (aquaporins), uncharged small solutes such as glycerol and/or gases across cellular membranes. The past year has brought significant advances in the characterization in plants of a large class this of water channel. MIPs have been identified in many single- and multi- cellular organisms. Aquaporins play important role in plant development and their adaptation to even changing environment. At the transcriptional level aquaporins have been up- or down-regulated in response to hormones, drought, salnity and light. Recent data indicate that plant aquaporin activity might be regulated by phosphorylation and intracellular protons. Novel mechanisms of regulation by hetero-tetramer formation or through control by reactive oxygen species and osmotic or hydrostatic pressure gradients is also discussed.

Transitory starch is accumulated during the day and is the main source of energy for the cell metabolism during the night. The observed periodical starch degradation has become a model often used by scientist in their experiments. Starch granule degradation could be divided into 2 periods: initiation of degradation and digestion of amylopectin and amylose into maltooligosaccharide and their derivative. Key meaning is attributed in this process to beta-amylaze, product of its activity beta-maltose is transported to the cytosole and there it subjects farthest conversions. It has been demonstrated that a number of enzymes take part in the starch degradation process. However, the way of regulating their activity is still not fully explained. There is most important elements effecting rate of starch decomposition: day cycle, starch phosphorylation and regulation of enzyme activity. It proceeds through redox potential, pH changes and phosphorylation of protein involved in starch degradation due specific phosphatases. The purpose of the current work is to systematize the knowledge of the Arabidopsis thaliana L. leaf starch degradation. The results of the recent research cast a new light on the starch degradation process as well as on its control.

Glycosylation, consisting in incorporation of single beta-N-acetyl-D-glucosamine residues attached by O-linkage to serine or threonine residues, is a common modification of cytoplasmic and nuclear proteins. Up to now about 200 proteins modified by O-GlcNAc have been identified including transcription factors, signaling components and metabolic enzymes. O-GlcNAc modified proteins can be also phosphorylated. In some cases O-GlcNAc and O-phosphate alternatively occupy the same sites. It has been suggested, that in signal transduction, instead of simple regulation by phosphorylation, more complex mechanism including glycosylation, is involved. Presented work focus on the structure and function of enzymes involved in O-GlcNAc modification and the role of this modification in regulating signal transduction and transcription.

Recent plant genome analyses have revealed a large number of genes encoding receptor-like kinases (RLKs) in plants. Theyare transmembrane proteins structurally related to the animal tyrosine and serin/threonine families with differences in their extracellular domains. There are more than 20 classes of plant RLKs, distinguished according to their extracellular domains, which can potentially bind an array of molecules. Although the majority of these RLKs remains uncharacterized, several members of this family are known to function in a diverse biological processes including plant growth and development, self-incompatibility, hormone perception and plant-microbe interactions. Despite knowledge of RLKs functions is increasing rapidly, yet major challenges remain. These include identifying ligands that activate RLKs and characterizing downstream pathways.

SR proteins are components of the spliceosome, a dynamic complex catalysing removal of pre-mRNA introns during splicing reaction. Recent studies have shown additional functions for SR proteins in mRNA transport and translation. Several protein kinases have been identified that can phosphorylate SR proteins. Phosphorylation is a common posttranslational modification among proteins. However in the case of SR proteins it has got a special meaning. Phosphorylation of serine residues clustered in a narrow area of RS domains affects all aspects of SR proteins functions. It influences subcellular localization and determines process in which the proteins take part.

Unlabelled: The aim of this work was to determine the bioaccumulation of fluoride and some metals (Cu, Zn, Pb) in tissues of snails under strictly controlled conditions expecting with this approach to verify the hypothesis that snails are suitable for the monitoring of environmental hazards. Additionally, the toxicity of fluorides administered orally on the energy balance of the snail's foot was investigated basing on concentrations of nucleosides, nucleotides and their products measured with high-performance liquid chromatography (HPLC). Two parallel snail cultures were started. The effect of dose on tissue levels of fluoride and metals was studied in the first part of the experiment. The second part served to study the effects of fluoride on energy metabolism of foot muscle (Tab. 1). Quantitation of fluoride and metal levels was done in soft tissues (foot, hepatopancreas) and shells of snails. Qualitative and quantitative analysis of purine compounds was performed in slices of foot. Fluoride concentrations in pulverized shells were measured using an ion-selective electrode. Gas chromatography served to determine fluoride concentrations in soft tissues (hepatopancreas and foot). Concentrations of metals were determined spectrophotometrically. Fluoride and metal content was calculated basing on weight of the pulverized sample. Purines were measured in foot muscle slices with high-performance liquid chromatography (HPLC). Concentrations were adjusted for protein content of sample. Concentrations of the following nucleosides, nucleotides and their products were determined: ATP, ADP, AMP, Ado (adenosine), GTP, GDP, GMP, Guo (guanosine), Hyp (hypoxanthine), IMP, Ino (inosine), Xan (xanthine), Urd (uridine), UA (uric acid), NAD+, and NADP (Fig. 1.). Statistical analysis was done with non-parametric test of Kruskal-Wallis, Mann-Whitney U-test and Spearman Rank Correlation Coefficient., Conclusions: 1. Accumulation in the shell was significantly increased at the lowest concentration of fluoride, but levels remained below those in the foot or hepatopancreas. It can be inferred that due to low sensitivity, accumulation of fluoride in soft tissues is not a suitable indicator for biomonitoring purposes. Shells seem to be more suited for this aim. 2. Due to low sensitivity, accumulation of metals in soft tissues is not a suitable indicator for biomonitoring purposes. 3. Fluoride had a statistically significant effect on the energy metabolism in muscle, especially on the content of AMP and GMP (Fig. 3, 4). The content of adenylate derivatives was increased (Fig. 3, 4) and phosphorylation of ADP to ATP was inhibited (Fig. 2, 5). 4. An increase in TAN and AEC with 1330 mg F-/kg seems to result from inhibition by fluoride of energy-consuming processes (Fig. 5). 5. In cases of high levels of fluoride it seems reasonable to measure the content of AMP, GMP, Guo or the value of AEC which appear to serve as universal indicators of depressed metabolic function (Fig. 3, 4, 5, 6).

This review focuses on results of patch-clamp studies on modulation of T lymphocyte potassium channel activity by physiologically relevant factors. In the preface the patch-clamp technique is briefly presented and basic properties of potassium channels in T lymphocytes are characterised. The paper contains an overview of the data on modulatory effects of extracellular and intracellular pH, temperature, extracellular potassium, extracellular divalent and trivalent metal cations, channel phosphorylation processes and membrane lipid metabolities on potassium channel activity. Some still unresolved problems in that area are indicated.

The tyrosine hydroxylase plays a key role in the catecholamine synthesis responding to many stimuli disturbing homeostasis. In this part we described the posttranscriptional levels of the gene and the protein regulation including: alternative splicing, isoform specificity, feedback inhibition, protein phosphorylation and dephosphorylation, protein stability, translational regulation.

Interleukin-2 (IL-2) and interleukin-12 (IL-12) belong to lympho-hematopoietic cytokines and play a critical role in the promotion and enhancement of cellular response. IL-2 as the second signal of antigenic stimulation facilitates the transition of the cell cycle from phase G1 to phase S and is responsible for the regulation of T lymphocytes proliferation and the activation of cytotoxic T cells, natural killers, macrophages and granulocytes. IL-12 is the dominant factor in T helper cells polarization leading to the secretion of IFN-gamma. Receptors for both of the cytokines (IL-2R or IL-12R) represent class I cytokine receptors composed of multiple subunits. Generally, they contain a similar extracellular conserved motif of four cysteines, and amino acid sequence--WSXWS (interacting directly with ligand) but possess no catalytic domens in the intrinsic tail of the chains. For this reason, to transfer the impact, the association with number of signaling molecules, allowing the activation of the signaling pathways is required. The connections of IL-2R or IL-12R with their ligands recruit receptor-associated cytoplasmic proteins from the JAK family (JAK1/JAK3 or JAK2/TYK2, respectively), which catalyze the phosphorylation of themselves and intrinsic tyrosine residues on the receptor, creating STAT docking sites. This phosphorylated and subsequent dimerised proteins bind rapidly to DNA and activate it. This review, presents the differences and similarities between the signaling pathways triggered by IL-2R or IL-12R ligation.

The Rab proteins are small GTP-binding proteins and form the largest group within the Ras superfamily. Around 60 mammalian Rab proteins are known. Each Rab is localised to a specific subcellular compartment. Rabs are involved in vesicular traffic of proteins between all compartments of the cell during the exocytic and endocytic pathways. Rabs also interact with cytoskeletal elements and influence the movement of intracellular membrane vesicles and tubules. The Rab proteins are posttranslationally modified at their C-termini by addition of the 20-carbon isoprenoid, geranylgeranyl, mediated by Rab GGTase and this modification is crucial for their function. Mutations in genes encoding proteins essential for the prenylation reaction, Rab Escort Protein and Rab geranylgeranyl transferase, lead to genetic diseases called Choroideremia and Hermansky-Pudlak syndrome.

The aim of the present immunohistochemical study was to investigate distribution of dopamine D1 receptors in the paraventricular nucleus of hypothalamus and to estimate whether D1 receptors colocalize with pCREB protein, a functional marker of stimulation generated via receptors positively linked to cAMP/PKA system. D1 receptors were found in numerous neurones of the paraventricular nucleus of hypothalamus, especially in its magnocellular part. In double-staining experiment, 74% of all stained neurones showed colocalization of D1 receptors and pCREB protein, 23% of neurones was pCREB-positive only and 3%--D1 receptor-positive only. The presence of D1 receptors in the paraventricular nucleus of hypothalamus indicates that these receptors may be possibly engaged in regulation of the endocrine system (release of oxytocin, vasopressin or CRH). Almost complete colocalization of D1 receptors with pCREB protein suggests that these receptors are likely functional (active). The presence of D1 receptors and pCREB protein in studied structures of rat brain, as well as the specificity of applied antibodies were confirmed by Western Blot method. It was demonstrated that antibodies against D1 receptor and pCREB protein recognized main bands with molecular weight approximately 40 and approximately 46 kDa, respectively, what correlates well with the literature data.

Acidic fibroblast growth factor belongs to the fibroblast growth factor family. It is a potent mitogenic agent. The growth factor acts through activation of specific cell-surface receptors leading to intracellular tyrosine phosphorylation cascade. In addition to its extracellular action, however, there are reports indicating that aFGF enters cells and that it has an intracellular function as well. Using different experimental approaches it was found that: 1) aFGF can stimulate DNA synthesis in cells without specific receptors when is translocated into cells as a fusion protein with diphtheria toxin, 2) the growth factor as such is able to enter cells expressing FGF receptors and localize in nuclei, and 3) an intracellular protein, which specifically binds only to mitogenic aFGF was found as well. Therefore it might be concluded, that transport of the growth factor from the cell-surface into the nucleus is an important event in the mechanism of stimulation of DNA synthesis and activation the proliferation program during aFGF treatment.

An age-related dysfunction of the immune system, and especially of the T lymphocytes, is the most common feature observed during aging. It is well recognized by now that changes in the molecular mechanisms connecting the antigen receptor of the T cell with its nuclear machinery, commonly called 'signal transduction pathways' are the basis for this dysfunction. This paper is an up-to-date review of current literature of the problem, describing age-related changes in the functioning of three major, complementary pathways of signal transduction in murine and human T cell: IP3/Ca2+/calcineurin, DAG/protein kinase C (PKC) and Ras/MAP kinases, discovered so far.

On the basis of recent reports we discuss the role of Vav in TCR-dependent signaling pathways. The Vav protein is GDP/GTP exchange factor for Rac, which initiates transduction of signals in JNK pathway. Upon stimulation of TCR by antigenic peptides, Vav associates with Zap-70 in TCR/CD3 signaling complex and becomes phosphorylated on Tyr-174 by tyrosine kinase Lck. The function of Vav is modulated by substrates and products of PI3-kinase activated by interaction of CD28 on thymocytes with B7 on antigen presenting cells. The PI3-kinase substrates inhibit activation of Vav, while the products enhance phosphorylation and activation of Vav by Lck. It seems that Vav functions in key point of TCR-mediated signaling pathway, which is regulated by costimulatory molecule (CD28) necessary for negative selection. The Vav-mediated integration of signals results in positive or negative selection of thymocytes.