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The MRTFs (myocardin-releated transcription factors) protein family consists of myocardin, MRTF-A (MKL1, MAL) and MRTF-B (MKL2). These proteins are included in the common family due to the presence of evolutionarily conserved domains which are responsible for homo- and heterodimerization with other members of the family as well as actin binding and transcription activation. Despite high structural homology, these factors present different characteristics in terms of localization. The expression of myocardin is limited to the myocardial cells and smooth muscle cells, exclusively, whereas MRTF-A and MRTF-B are commonly found in various cells and tissues. These proteins interact with MADS box transcription factors as well as serum response factors (SRF) thus being engaged into signal transduction, which results from cytoskeleton reorganisation, from cytoplasm to the nucleus. It has been concluded that these proteins both take part in muscle tissue differentiation as well as mediate the development of pathological conditions (vascular diseases, cancer and fibrosis).

Filamin A (FLNA, filamin-1) is a homodimeric protein, commonly expressed in animal organisms. Its basic function in the cell is actin crosslinking and forming 3D cytoskeleton structure. Filamin-1 interacts with more than 60 different proteins with various functions such as: cell membrane and cytoskeleton formation, maintaining cell shape, intracellular signaling, nuclear functions or GTP-binding proteins regulation. FLNA interactions with oncogenesis- and metastasis-related proteins, such as K-RAS, TRAF2 or NIK indicate its crucial role in cancer progression. Filamin-1 undergoes proteolytic fragmentation producing products, translocation of which to the nucleus may be related to alterations in the cell metastatic ability. It was also demonstrated that FLNA dysfunctions can lead to sensitization of cells to ionizing irradiation or common chemotherapeutics: bleomycin and cisplatin. These findings indicate that FLNA can be considered as a novel target in anti-cancer therapy.

Rho proteins, including RhoA, Rac1 and Cdc42, are members of the Ras superfamily of monomeric GTP-binding proteins, which are well-known regulators of the cytoskeleton. Numerous studies have shown that an intact cytoskeleton is required for cell cycle progression through G1 phase as well as mitosis and cytokinesis. Because of their role in both cytoskeletal rearrangement and mitogenic signaling, Rho family proteins are key mediators of cell cycle progression. In this paper, we review the current state of knowledge concerning the Rho-dependent signaling pathways that regulate the expression of cell cycle regulatory proteins required for G1 phase progression and S phase entry.

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 Rho proteins are members of the Ras superfamily of small GTPases. They are thought to be crucial regulators of multiple signal transduction pathways that influence a wide range of cellular functions, including migration, membrane trafficking, adhesion, polarity and cell shape changes. Thanks to their ability to control the assembly and organization of the actin and microtubule cytoskeletons, Rho GTPases are known to regulate mitosis and cytokinesis progression. These proteins are required for formation and rigidity of the cortex during mitotic cell rounding, mitotic spindle formation and attachment of the spindle microtubules to the kinetochore. In addition, during cytokinesis, they are involved in promoting division plane determination, contractile ring and cleavage furrow formation and abscission. They are also known as regulators of cell cycle progression at the G1/S and G2/M transition. Thus, the signal transduction pathways in which Rho proteins participate, appear to connect dynamics of actin and microtubule cytoskeletons to cell cycle progression. We review the current state of knowledge concerning the molecular mechanisms by which Rho GTPase signaling regulates remodeling of actin and microtubule cytoskeletons in order to control cell division progression.

Myosins are actin-based motor proteins that use energy derived from ATP hydrolysis to generate force and move along actin filaments. Myosin VI is a unique motor protein because it moves towards the "minus" end of actin filament, which is the opposite direction to all of the other myosins studied so far, and therefore is thought to have unique properties and cellular functions. Localization and functional studies indicate that myosin VI plays a role in a variety of different intracellular processes, such as endocytosis and secretion as well as cell division, differentiation, and cell migration. These various functions of myosin VI are mediated by interaction with a range of different binding partners. In this review, we describe the structure, kinetic properties and functions proposed for myosin VI, and present current hypotheses on the mechanisms of functioning of this unique protein in vivo.

The superfamily of small, monomeric GTP-binding proteins, in Arabidopsis thaliana comprising 93 members, is classified into four families: Arf/Sar, Rab, Rop/Rac, and Ran families. All monomeric G proteins function as molecular switches that are activated by GTP and inactivated by the hydrolysis of GTP to GDP. GTP/GDP cycling is controlled by three classes of regulatory protein: guanine-nucleotide-exchange factors (GEFs), GTPase-activating proteins (GAPs), and guanine-nucleotide-dissociation inhibitors (GDIs). Proteins of Arf family are primarily involved in regulation of membrane traffic and organization of the cytoskeleton. Arf1/Sar1 proteins regulate the formation of vesicle coat at different steps in the exocytic and endocytic pathways. Rab GTPases are regulators of vesicular transport. They are involved in vesicle formation, recruitment of cytoskeletal motor proteins, and in vesicle tethering and fusion. Rop proteins serve as key regulators of cytoskeletal reorganization in response to extracellular signals. Several data have also shown that Rop proteins play additional roles in membrane trafficking and regulation of enzymes activity. Ran proteins are involved in nucleocytoplasmic transport.

The review is devoted for the occurance, meaning of silicon and their compounds, especially silicon acids and silicones. Silicon participates in biosynthesis of collagen, the basic component of connective tissue. It strengthens and makes the walls of blood vessels more flexible, diminishes capillaries permeability, accelerates healing processes, has a sebostatic activity, strengthens hair and nails. This element has a beneficial effect on phosphorylation of proteins saccharides, and nucleotides. It is also essential for the formation of cytoskeleton and other cellular structures of mechanical or supportive function. Silicon is an initial substrate for obtaining silicones. These are synthetic polymers, in which silicon atoms are bound by oxygen bridges. They are used in almost all kinds of products due to their most convenient physical and chemical properties: moistening and film-forming, giving liquid form increasing solubility. Silicon acids form colloid gel, silica gel, with absorptive abilities, like active carbon.

Proteins of the Rho protein family (RhoA, Rac1, Cdc42) work as molecular switches in the regulation of many cellular processes. They are involved in cell migration, cell-cycle control, apoptosis, and the regulation of gene transcription. Rho proteins show their activity mainly in the cell's cytoskeleton by taking part in the reorganization of microfilaments and microtubules. In recent years, significant progress has been made in understanding the biochemical and genetic nature of many processes controlled by Rho proteins. Although there are still seveal unknowns and hypothesizes which require confirmation, newer and more precise experimental results allow us to better understand these processes. It has also been suggested to use Rho family proteins in the therapy of some diseases. The purpose of this study was to characterize the significance of Rho processes in the cellular cytoskeleton.

Phospholipase C (PLC) catalyzes the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2) to yield diacylglycerol (DAG) and inositol-1,4,5-triphosphate (IP3). Phospholipase C activities have been described in several organisms, including bacteria, yeast, plants, and mammals. In mammalian cells, PLC (PLC-beta, PLC-gamma, PLC-delta, PLC-epsilon, PLC-zeta, and PLC-eta isoforms) has been implicated in intracellular signal transduction, vesicle transport, endocytosis, exocytosis, ion channel function, mitosis, cytoskeletal reorganization, and neuronal signal transduction. Mammalian phospholipase C is regulated by many factors, including calcium ions, receptor tyrosine kinases, and small G-proteins of the Ras and Rho families. In this review the structure and biological function of PLC are discussed.

The postsynaptic density (PSD) is a dynamic multi-protein complex attached to the postsynaptic membrane composed of several hundred proteins such as receptors and channels, scaffolding and adaptor proteins, cell-adhesion proteins, cytoskeletal proteins, G-proteins and their modulators and signaling molecules including kinases and phosphtases. This review focuses on the prominent PSD scaffolds proteins such as members of the MAGUK (membrane-associated guanylyl kinase), Shank (SH3 domain and ankyrin repeat-containing protein) and Homer families. These molecules interact simultaneously with different kinds of receptors and modulate their function by linking the receptors to downstream signaling events. For example PSD 95, a main member of MAGUK family, interacts directly with carboxyl termini of NMDA receptor subunits and clusters them to the postsynaptic membrane. In addition, PSD 95 is involved in binding and organizing proteins connected with NMDAR signaling. Based on the modular character and ability to form multiproteins interactions, MAGUK, Shank and Homer are perfectly suited to act as a major scaffold in postsynaptic density.

Microfilaments, microtubules, and intermediate filaments form the cytoskeleton. These substructures play a significant role in cell motility, transport, divisions, differentiation, tumor transformation, and apoptosis. These processes are related with changes in cell shape, in which cytoskeletal proteins take an active part. In non-muscle cells, actin is an essential constituent of microfilaments, tubulin forms microtubules, and vimentin is one of the characteristic proteins of intermediate filaments. The differentiation of cells is associated inseparably with tissue and organ formation, and the induction of malignant cell differentiation can be a method of treatment, especially in hematopoietic steam cell disease therapy. In studies on tumor cell differentiation, agents such as cytokines, retinoids, forbol esters, and vitamin D3 are the most commonly used, and results show these substances may participate in different pathways of signal transduction. Retinoids and vitamin D3 mostly affect gene transcription via nuclear receptors, whereas cytokines act through membrane receptors. The results of studies show actin, tubulin, and vimentin reorganization during the differentiation of leukemia cells, but it remains unknown whether the observed changes are the cause or the result of the differentiation process.

Migration of crawling cells (amoebae and some kinds of the tissue cells) is a process related to the dynamic reorganization of actomyosin cytoskeleton. That reorganization engages actin polymerization and de-polymerization, branching of actin network and interaction of myosin II with actin filaments. All those cytoskeleton changes lead to the cell progression, contraction and shifting of the uropod and the cell adhesion. Numerous external stimuli, which activate various surface receptors and signal transduction pathways, can promote migration. Rho family proteins play an important role in the regulation of actin cytoskeleton organization. The most known members of this family are Rho, Rac and Cdc42 proteins, present in all mammalian tissue cells. These proteins control three different stages of cell migration: progression of the frontal edge, adhesion which stabilizes the frontal area, and de-adhesion and shifting of the uropod. Cdc42 and Rac control cell polarization, lamellipodium formation and expansion, organization of focal complexes. Rho protein regulates contractile activity of actomyosin cytoskeleton outside the frontal area, and thus contraction and de-adhesion of the uropod.

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 literature review dealing with participation of proteolytic enzymes in initiation and execution of apoptosis was done. Cysteine proteases with Asp-X cleavage specificity, called caspases, play the main role in this process. The other proteases such calpains and proteasomes take also part in apoptosis. The proteases degrade proteins of cytoskeleton and structural proteins of nucleus, they also activate proendonucleases.