Regulation of Notch1 Signalling by Long Non-Coding RNAs in Cancers and Other Health Disorders.

Notch1 signalling plays a multifaceted role in tissue development and homeostasis. Currently, due to the pivotal role of Notch1 signalling, the relationship between NOTCH1 expression and the development of health disorders is being intensively studied. Nevertheless, Notch1 signalling is not only controlled at the transcriptional level but also by a variety of post-translational events. First is the ligand-dependent mechanical activation of NOTCH receptors and then the intracellular crosstalk with other signalling molecules-among those are long non-coding RNAs (lncRNAs). In this review, we provide a detailed overview of the specific role of lncRNAs in the modulation of Notch1 signalling, from expression to activity, and their connection with the development of health disorders, especially cancers.

Histone 3 Lysine 27 Trimethylation Signature in Breast Cancer.

Cancer development and progression rely on complicated genetic and also epigenetic changes which regulate gene expression without altering the DNA sequence. Epigenetic mechanisms such as DNA methylation, histone modifications, and regulation by lncRNAs alter protein expression by either promoting gene transcription or repressing it. The presence of so-called chromatin modification marks at various gene promoters and gene bodies is associated with normal cell development but also with tumorigenesis and progression of different types of cancer, including the most frequently diagnosed breast cancer. This review is focused on the significance of one of the abundant post-translational modifications of histone 3- trimethylation of lysine 27 (H3K27me3), which was shown to participate in tumour suppressor genes' silencing. Unlike other reviews in the field, here the overview of existing evidence linking H3K27me3 status with breast cancer biology and the tumour outcome is presented especially in the context of diverse breast cancer subtypes. Moreover, the potential of agents that target H3K27me3 for the treatment of this complex disease as well as H3K27 methylation in cross-talk with other chromatin modifications and lncRNAs are discussed.

Vorinostat (SAHA) and Breast Cancer: An Overview.

Vorinostat (SAHA), an inhibitor of class I and II of histone deacetylases, is the first histone deacetylase inhibitor (HDI) approved for the treatment of cutaneous T-cell lymphoma in 2006. HDIs are promising anticancer agents that inhibit the proliferation of many types of cancer cells including breast carcinoma (BC). BC is a heterogeneous disease with variable biological behavior, morphological features, and response to therapy. Although significant progress in the treatment of BC has been made, high toxicity to normal cells, serious side effects, and the occurrence of multi-drug resistance limit the effective therapy of BC patients. Therefore, new active agents which improve the effectiveness of currently used regimens are highly needed. This manuscript analyzes preclinical and clinical trials data of SAHA, applied individually or in combination with other anticancer agents, considering different histological subtypes of BC.

Phosphorylation of the conserved C-terminal domain of ribosomal P-proteins impairs the mode of interaction with plant toxins.

The ribosome is subjected to post-translational modifications, including phosphorylation, that affect its biological activity. Among ribosomal elements, the P-proteins undergo phosphorylation within the C terminus, the element which interacts with trGTPases or ribosome-inactivating proteins (RIPs); however, the role of phosphorylation has never been elucidated. Here, we probed the function of phosphorylation on the interaction of P-proteins with RIPs using the ribosomal P1-P2 dimer. We determined the kinetic parameters of the interaction with the toxins using biolayer interferometry and microscale thermophoresis. The results present the first mechanistic insight into the function of P-protein phosphorylation, showing that introduction of a negative charge into the C terminus of P1-P2 proteins promotes α-helix formation and decreases the affinity of the P-proteins for the RIPs.

Decoding LncRNAs.

Non-coding RNAs (ncRNAs) have been considered as unimportant additions to the transcriptome. Yet, in light of numerous studies, it has become clear that ncRNAs play important roles in development, health and disease. Long-ignored, long non-coding RNAs (lncRNAs), ncRNAs made of more than 200 nucleotides have gained attention due to their involvement as drivers or suppressors of a myriad of tumours. The detailed understanding of some of their functions, structures and interactomes has been the result of interdisciplinary efforts, as in many cases, new methods need to be created or adapted to characterise these molecules. Unlike most reviews on lncRNAs, we summarize the achievements on lncRNA studies by taking into consideration the approaches for identification of lncRNA functions, interactomes, and structural arrangements. We also provide information about the recent data on the involvement of lncRNAs in diseases and present applications of these molecules, especially in medicine.

Expression of maize calcium-dependent protein kinase (ZmCPK11) improves salt tolerance in transgenic Arabidopsis plants by regulating sodium and potassium homeostasis and stabilizing photosystem II.

In plants, CALCIUM-DEPENDENT PROTEIN KINASES (CDPKs/CPKs) are involved in calcium signaling in response to endogenous and environmental stimuli. Here, we report that ZmCPK11, one of maize CDPKs, participates in salt stress response and tolerance. Salt stress induced expression and upregulated the activity of ZmCPK11 in maize roots and leaves. Activation of ZmCPK11 upon salt stress was also observed in roots and leaves of transgenic Arabidopsis plants expressing ZmCPK11. The transgenic plants showed a long-root phenotype under control conditions and a short-root phenotype under NaCl, abscisic acid (ABA) or jasmonic acid (JA) treatment. Analysis of ABA and JA content in roots indicated that ZmCPK11 can mediate root growth by regulating the levels of these phytohormones. Moreover, 4-week-old transgenic plants were more tolerant to salinity than the wild-type plants. Their leaves were less chlorotic and showed weaker symptoms of senescence accompanied by higher chlorophyll content and higher quantum efficiency of photosystem II. The expression of Na+ /K+ transporters (HKT1, SOS1 and NHX1) and transcription factors (CBF1, CBF2, CBF3, ZAT6 and ZAT10) with known links to salinity tolerance was upregulated in roots of the transgenic plants upon salt stress. Furthermore, the transgenic plants accumulated less Na+ in roots and leaves under salinity, and showed a higher K+ /Na+ ratio in leaves. These results show that the improved salt tolerance in ZmCPK11-transgenic plants could be due to an upregulation of genes involved in the maintenance of intracellular Na+ and K+ homeostasis and a protection of photosystem II against damage.

Functional Analysis of the Ribosomal uL6 Protein of Saccharomyces cerevisiae.

The genome-wide duplication event observed in eukaryotes represents an interesting biological phenomenon, extending the biological capacity of the genome at the expense of the same genetic material. For example, most ribosomal proteins in Saccharomyces cerevisiae are encoded by a pair of paralogous genes. It is thought that gene duplication may contribute to heterogeneity of the translational machinery; however, the exact biological function of this event has not been clarified. In this study, we have investigated the functional impact of one of the duplicated ribosomal proteins, uL6, on the translational apparatus together with its consequences for aging of yeast cells. Our data show that uL6 is not required for cell survival, although lack of this protein decreases the rate of growth and inhibits budding. The uL6 protein is critical for the efficient assembly of the ribosome 60S subunit, and the two uL6 isoforms most likely serve the same function, playing an important role in the adaptation of translational machinery performance to the metabolic needs of the cell. The deletion of a single uL6 gene significantly extends the lifespan but only in cells with a high metabolic rate. We conclude that the maintenance of two copies of the uL6 gene enables the cell to cope with the high demands for effective ribosome synthesis.

Multiplication of Ribosomal P-Stalk Proteins Contributes to the Fidelity of Translation.

The P-stalk represents a vital element within the ribosomal GTPase-associated center, which represents a landing platform for translational GTPases. The eukaryotic P-stalk exists as a uL10-(P1-P2)2 pentameric complex, which contains five identical C-terminal domains, one within each protein, and the presence of only one such element is sufficient to stimulate factor-dependent GTP hydrolysis in vitro and to sustain cell viability. The functional contribution of the P-stalk to the performance of the translational machinery in vivo, especially the role of P-protein multiplication, has never been explored. Here, we show that ribosomes depleted of P1/P2 proteins exhibit reduced translation fidelity at elongation and termination steps. The elevated rate of the decoding error is inversely correlated with the number of the P-proteins present on the ribosome. Unexpectedly, the lack of P1/P2 has little effect in vivo on the efficiency of other translational GTPase (trGTPase)-dependent steps of protein synthesis, including translocation. We have shown that loss of accuracy of decoding caused by P1/P2 depletion is the major cause of translation slowdown, which in turn affects the metabolic fitness of the yeast cell. We postulate that the multiplication of P-proteins is functionally coupled with the qualitative aspect of ribosome action, i.e., the recoding phenomenon shaping the cellular proteome.

Functional analysis of the uL11 protein impact on translational machinery.

The ribosomal GTPase associated center constitutes the ribosomal area, which is the landing platform for translational GTPases and stimulates their hydrolytic activity. The ribosomal stalk represents a landmark structure in this center, and in eukaryotes is composed of uL11, uL10 and P1/P2 proteins. The modus operandi of the uL11 protein has not been exhaustively studied in vivo neither in prokaryotic nor in eukaryotic cells. Using a yeast model, we have brought functional insight into the translational apparatus deprived of uL11, filling the gap between structural and biochemical studies. We show that the uL11 is an important element in various aspects of 'ribosomal life'. uL11 is involved in 'birth' (biogenesis and initiation), by taking part in Tif6 release and contributing to ribosomal subunit-joining at the initiation step of translation. uL11 is particularly engaged in the 'active life' of the ribosome, in elongation, being responsible for the interplay with eEF1A and fidelity of translation and contributing to a lesser extent to eEF2-dependent translocation. Our results define the uL11 protein as a critical GAC element universally involved in trGTPase 'productive state' stabilization, being primarily a part of the ribosomal element allosterically contributing to the fidelity of the decoding event.

Maize calcium-dependent protein kinase (ZmCPK11): local and systemic response to wounding, regulation by touch and components of jasmonate signaling.

Expression of ZmCPK11, a member of the maize (Zea mays) calcium-dependent protein kinases (CDPKs) family, is induced by mechanical wounding. A rapid increase of the activity of a 56-kDa CDPK has been observed in damaged leaves. In the present work, it is shown that the 56-kDa CDPK, identified as ZmCPK11, is also activated in non-wounded leaves as an element of systemic wound response. Moreover, an increase of the enzyme's activity and induction of ZmCPK11 expression was observed after touching the leaves. To study the role of ZmCPK11 in wound and touch signaling, transgenic Arabidopsis thaliana plants in which c-Myc-ZmCPK11 was expressed under control of the CaMV 35S promoter were generated. Analysis of the transgenic plants showed that c-Myc-ZmCPK11 was activated upon wounding and touching. Furthermore, pre-treatment with acetylsalicylic acid (acSA), an inhibitor of jasmonic acid (JA)-dependent wound signaling, abolished the wound-induced activation of ZmCPK11 in maize and the transgenic A. thaliana plants. Methyl jasmonate (MeJA) and linolenic acid (LA) stimulated the activity of ZmCPK11 as well as induced the expression of ZmCPK11 and other wound-responsive genes, lipoxygenase 1 (ZmLOX1) and proteinase inhibitor 1 (ZmWIP1). These results indicate that ZmCPK11, regulated at the enzymatic and transcriptional level by LA and MeJA, is a component of touch- and wound-induced pathway(s), participating in early stages of local and systemic responses.