The Actin Motor Protein Myosin 6 Contributes to Cell Migration and Expression of GIPC1 and Septins in Breast Cancer Cells.

Introduction: Breast cancer is highly metastatic. One protein that may participate in breast cancer cell migration is the actin motor protein myosin 6 (MYO6), which is likely regulated by the GIPC1 protein. Additionally, septins (SEPTs) appear to participate in breast cancer motility.

Plant-specific calreticulin is localized in the nuclei of highly specialized cells in the pistil-new observations for an old hypothesis.

One of the first cellular locations of the calreticulin (CRT) chaperone in eukaryotic cells, apart from its obvious localization in the endoplasmic reticulum (ER), was the cell nucleus (Opas et al. 1991). The presence of CRT has been detected inside the nucleus and in the nuclear envelope of animal and plant cells, and a putative nuclear localization signal (NLS) in the CRT amino acid sequence has been mapped in several animal and plant species.

Unconventional myosin VI in the heart: Involvement in cardiac dysfunction progressing with age.

Hypertrophic cardiomyopathy is the most common cardiovascular disease, which is characterized by structural and functional myocardial abnormalities. It is caused predominantly by autosomal dominant mutations, mainly in genes encoding cardiac sarcomeric proteins, resulting in diverse phenotypical patterns and a heterogenic clinical course. Unconventional myosin VI (MVI) is one of the proteins important for heart function, as it was shown that a point mutation within MYO6 is associated with left ventricular hypertrophy.

RNAi-Mediated Knockdown of Calreticulin3a Impairs Pollen Tube Growth in .

Pollen tube growth depends on several complex processes, including exo/endocytosis, cell wall biogenesis, intracellular transport, and cell signaling. Our previous results provided evidence that calreticulin (CRT)-a prominent calcium (Ca)-buffering molecular chaperone in the endoplasmic reticulum (ER) lumen-is involved in pollen tube formation and function. We previously cloned and characterized the gene belonging to the 2 subgroup from (), and found that post-transcriptional silencing of expression strongly impaired pollen tube growth in vitro.

Calreticulin expression and localization in relation to exchangeable Ca during pollen development in Petunia.

Background: Pollen development in the anther in angiosperms depends on complicated cellular interactions associated with the expression of gametophytic and sporophytic genes which control fundamental processes during microsporo/gametogenesis, such as exo/endocytosis, intracellular transport, cell signaling, chromatin remodeling, and cell division. Most if not all of these cellular processes depend of local concentration of calcium ions (Ca). Work from our laboratory and others provide evidence that calreticulin (CRT), a prominent Ca-binding/buffering protein in the endoplasmic reticulum (ER) of eukaryotic cells, may be involved in pollen formation and function.

Dynamic distribution of ARGONAUTE1 (AGO1) and ARGONAUTE4 (AGO4) in Hyacinthus orientalis L. pollen grains and pollen tubes growing in vitro.

The transcriptional and posttranscriptional AGO-mediated control of gene expression may play important roles during male monocot gametophyte development. In this report, we demonstrated dynamic changes in the spatiotemporal distribution of AGO1 and AGO4, which are key proteins of the RNA-induced silencing complex (RISC) in Hyacinthus orientalis male gametophyte development. During maturation of the bicellular pollen grains and in vitro pollen tube growth, the pattern of AGO1 localization was correlated with previously observed transcriptional activity of the cells.

Myosin VI maintains the actin-dependent organization of the tubulobulbar complexes required for endocytosis during mouse spermiogenesis†‡.

Myosin VI (MYO6) is an actin-based motor that has been implicated in a wide range of cellular processes, including endocytosis and the regulation of actin dynamics. MYO6 is crucial for actin/membrane remodeling during the final step of Drosophila spermatogenesis, and MYO6-deficient males are sterile. This protein also localizes to actin-rich structures involved in mouse spermiogenesis.

Phylogenetic analysis of plant calreticulin homologs.

Calreticulin (CRT) is an multifunctional resident endoplasmic reticulum (ER) luminal protein implicated in regulating a variety of cellular processes, including Ca storage/mobilization and protein folding. These multiple functions may be carried out by different CRT genes and protein isoforms. The plant CRT family consist of three genes: CRT1 and CRT2 classified in the common subclass (CRT1/2), and CRT3.

Myosin VI in the nucleus of neurosecretory PC12 cells: Stimulation-dependent nuclear translocation and interaction with nuclear proteins.

Myosin VI (MVI) is a unique actin-based motor protein moving towards the minus end of actin filaments, in the opposite direction than other known myosins. Besides well described functions of MVI in endocytosis and maintenance of Golgi apparatus, there are few reports showing its involvement in transcription. We previously demonstrated that in neurosecretory PC12 cells MVI was present in the cytoplasm and nucleus, and its depletion caused substantial inhibition of cell migration and proliferation.

Calreticulin localizes to plant intra/extracellular peripheries of highly specialized cells involved in pollen-pistil interactions.

Calcium (Ca) plays essential roles in generative reproduction of angiosperms, but the sites and mechanisms of Ca storage and mobilization during pollen-pistil interactions have not been fully defined. Both external and internal Ca stores are likely important during male gametophyte communication with the sporophytic and gametophytic cells within the pistil. Given that calreticulin (CRT), a Ca-buffering protein, is able to bind Ca reversibly, it can serve as a mobile store of easily releasable Ca (so called an exchangeable Ca) in eukaryotic cells.

Expression and localization of myosin VI in developing mouse spermatids.

Myosin VI (MVI) is a versatile actin-based motor protein that has been implicated in a variety of different cellular processes, including endo- and exocytic vesicle trafficking, Golgi morphology, and actin structure stabilization. A role for MVI in crucial actin-based processes involved in sperm maturation was demonstrated in Drosophila. Because of the prominence and importance of actin structures in mammalian spermiogenesis, we investigated whether MVI was associated with actin-mediated maturation events in mammals.

Molecular characteristic and physiological role of DOPA-decarboxylase.

The enzyme DOPA decarboxylase (aromatic-L-amino-acid decarboxylase, DDC) plays an important role in the dopaminergic system and participates in the uptake and decarboxylation of amine precursors in the peripheral tissues. Apart from catecholamines, DDC catalyses the biosynthesis of serotonin and trace amines. It has been shown that the DDC amino acid sequence is highly evolutionarily conserved across many species.

Calreticulin is required for calcium homeostasis and proper pollen tube tip growth in Petunia.

Calreticulin is involved in stabilization of the tip-focused Ca gradient and the actin cytoskeleton arrangement and function that is required for several key processes driving Petunia pollen tube tip growth. Although the precise mechanism is unclear, stabilization of a tip-focused calcium (Ca) gradient seems to be critical for pollen germination and pollen tube growth. We hypothesize that calreticulin (CRT), a Ca-binding/buffering chaperone typically residing in the lumen of the endoplasmic reticulum (ER) of eukaryotic cells, is an excellent candidate to fulfill this role.

Nuclear matrix - structure, function and pathogenesis.

The nuclear matrix (NM), or nuclear skeleton, is the non-chromatin, ribonucleoproteinaceous framework that is resistant to high ionic strength buffers, nonionic detergents, and nucleolytic enzymes. The NM fulfills a structural role in eukaryotic cells and is responsible for maintaining the shape of the nucleus and the spatial organization of chromatin. Moreover, the NM participates in several cellular processes, such as DNA replication/repair, gene expression, RNA transport, cell signaling and differentiation, cell cycle regulation, apoptosis and carcinogenesis.

Late progamic phase and fertilization affect calreticulin expression in the Hyacinthus orientalis female gametophyte.

Calreticulin expression is upregulated during sexual reproduction of Hyacinthus orientalis, and the protein is localized both in the cytoplasm and a highly specialized cell wall within the female gametophyte. Several evidences indicate calreticulin (CRT) as an important calcium (Ca(2+))-binding protein that is involved in the generative reproduction of higher plants, including both pre-fertilization and post-fertilization events. Because CRT is able to bind and sequester exchangeable Ca(2+), it can serve as a mobile intracellular store of easily releasable Ca(2+) and control its local cytosolic concentrations in the embryo sac.

Molecular evidence that rough endoplasmic reticulum is the site of calreticulin translation in Petunia pollen tubes growing in vitro.

In germinating pollen grains and growing pollen tubes, CRT is translated on ER membrane-bound ribosomes in the regions where its activity is required for stabilization of tip-focused Ca (2+) gradient. Pollen tube growth requires coordination of signaling, exocytosis, and actin cytoskeletal organization. Many of these processes are thought to be controlled by finely tuned regulation of cytoplasmic Ca(2+) in discrete regions of the tube cytoplasm.

Mechanical transition in a highly stretched and torsionally constrained DNA.

We show results of our high force (up to 1.8 nN) atomic force microscopy force spectroscopy measurements of a double stranded DNA. We have found that the force spectra of torsionally constrained molecules display a small plateau occurring at a force of approximately 1 nN.

Calreticulin expression in relation to exchangeable Ca(2+) level that changes dynamically during anthesis, progamic phase, and double fertilization in Petunia.

Calcium (Ca(2+)) plays essential roles in plant sexual reproduction, but the sites and the mechanism of Ca(2+) mobile storage during pollen-pistil interactions have not been fully defined. Because the Ca(2+)-buffering protein calreticulin (CRT) is able to bind and sequester Ca(2+), it can serve as a mobile intracellular store of easily releasable Ca(2+) and control its local concentration within the cytoplasm. Our previous studies showed an enhanced expression of Petunia hybrida CRT gene (PhCRT) during pistil transmitting tract maturation, pollen germination and tube outgrowth on the stigma, gamete fusion, and early embryogenesis.

Molecular cloning and transcriptional activity of a new Petunia calreticulin gene involved in pistil transmitting tract maturation, progamic phase, and double fertilization.

Calreticulin (CRT) is a highly conserved and ubiquitously expressed Ca²⁺-binding protein in multicellular eukaryotes. As an endoplasmic reticulum-resident protein, CRT plays a key role in many cellular processes including Ca²⁺ storage and release, protein synthesis, and molecular chaperoning in both animals and plants. CRT has long been suggested to play a role in plant sexual reproduction.

Epigenetic, transcriptional and posttranscriptional regulation of the tyrosine hydroxylase gene.

The activity of tyrosine hydroxylase (TH, EC 1.14.16.

Calreticulin expression and localization in plant cells during pollen-pistil interactions.

In this report, the distributions of calreticulin (CRT) and its transcripts in Haemanthus pollen, pollen tubes, and somatic cells of the hollow pistil were studied. Immunoblot analysis of protein extracts from mature anthers, dry and germinated pollen, growing pollen tubes, and unpollinated/pollinated pistils revealed a strong expression of CRT. Both in vitro and in situ studies confirmed the presence of CRT mRNA and protein in pollen/pollen tubes and somatic cells of the pistil transmitting tract.

[Calreticulin--the structure, cell localizations and functions in animals and plants].

Calreticulin (CRT) is an ubiquitously expressed Ca2+ binding protein in endoplasmic reticulum (ER) of eukaryotic cells. A highly conserved structure between CRTs from different species of animals and plants confirms an important role of the protein in living cells. CRT has been found in different cellular compartments, suggesting to play a role in many cellular processes both inside and outside the ER.

[The multifunctionality of CHIP protein in the protein quality-control system].

Selective protein degradation depends on their quality being controlled by the cellular system, which includes chaperones involved in protein folding and two degradation systems, the proteasomal and lysosomal. CHIP (carboxyl terminus of Hsp70-interacting protein), an E3 ubiquitin ligase and co-chaperone, serves as a chaperone-degradation system interface. This article reviews the molecular characteristics of CHIP protein, the mechanism of its action, and its role in cellular metabolism and discusses how CHIP dysfunction may lead to neurodegenerative diseases.

The bovine tyrosine hydroxylase gene associates in vitro with the nuclear matrix by its first intron sequence.

Recently we have shown that in vitro binding of the proximal part of the human tyrosine hydroxylase gene to the nuclear matrix is correlated with its transcriptional activity. The strongest binding potential was predicted by computing for the first intron sequence (Lenartowski & Goc, 2002, Neurosci Lett.; 330: 151-154).