Photosynthetic electron transport rate (ETR) in the littoral herb Launaea sarmentosa known as mole crab in Thailand

Photosynthesis Research - Launaea sarmentosa (Willd.) Sch. Bip ex Kunze (Asteracaeae) is a littoral sand dune herb found in the Indian Ocean region, used as a folk medicine and as a savory...     

Chromatin regulation in schistosomes and histone modifying enzymes as drug targets

Only one drug is currently available for the treatment and control of schistosomiasis and the increasing risk of selecting strains of schistosome that are resistant to praziquantel means that the development of new drugs is urgent. With this objective we have chosen to target the enzymes modifying histones and in particular the histone acetyltransferases and histone deacetylases (HDAC). Inhibitors of HDACs (HDACi) are under intense study as potential anti-cancer drugs and act via the induction of cell cycle arrest and/or apoptosis. Schistosomes like other parasites can be considered as similar to tumours in that they maintain an intense metabolic activity and rate of cell division that is outside the control of the host. We have shown that HDACi can induce apoptosis and death of schistosomes maintained in culture and have set up a consortium (Schistosome Epigenetics: Targets, Regulation, New Drugs) funded by the European Commission with the aim of developing inhibitors specific for schistosome histone modifying enzymes as novel lead compounds for drug development.     

Epigenetic inactivation of the miR-124-1 in haematological malignancies

miR-124-1 is a tumour suppressor microRNA (miR). Epigenetic deregulation of miRs is implicated in carcinogenesis. Promoter DNA methylation and histone modification of miR-124-1 was studied in 5 normal marrow controls, 4 lymphoma, 8 multiple myeloma (MM) cell lines, 230 diagnostic primary samples of acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL), chronic myeloid leukaemia (CML), chronic lymphocytic leukaemia (CLL), MM, and non-Hodgkin's lymphoma (NHL), and 53 MM samples at stable disease or relapse. Promoter of miR-124-1 was unmethylated in normal controls but homozygously methylated in 4 of 4 lymphoma and 4 of 8 myeloma cell lines. Treatment of 5-Aza-2'-deoxycytidine led to miR-124-1 demethylation and re-expression of mature miR-124, which also associated with emergence of euchromatic trimethyl H3K4 and consequent downregulation of CDK6 in myeloma cells harboring homozygous miR-124-1 methylation. In primary samples at diagnosis, miR-124-1 methylation was absent in CML but detected in 2% each of MM at diagnosis and relapse/progression, 5% ALL, 15% AML, 14% CLL and 58.1% of NHL (p<0.001). Amongst lymphoid malignancies, miR-124-1 was preferentially methylated in NHL than MM, CLL or ALL. In primary lymphoma samples, miR-124-1 was preferentially hypermethylated in B- or NK/T-cell lymphomas and associated with reduced miR-124 expression. In conclusion, miR-124-1 was hypermethylated in a tumour-specific manner, with a heterochromatic histone configuration. Hypomethylation led to partial restoration of euchromatic histone code and miR re-expression. Infrequent miR-124-1 methylation detected in diagnostic and relapse MM samples showed an unimportant role in MM pathogenesis, despite frequent methylation found in cell lines. Amongst haematological cancers, miR-124-1 was more frequently hypermethylated in NHL, and hence warrants further study.     

High-throughput protein crystallization

High-throughput structural biology is a focus of a number of academic and pharmaceutical laboratories around the world. The use of X-ray crystallography in these efforts is critically dependent on high-throughput protein crystallization. The application of current protocols yields crystal leads for approximately 30% of the input proteins and well-diffracting crystals for a smaller fraction. Increasing the success rate will require a multidisciplinary approach that must invoke techniques from molecular biology, protein biochemistry, biophysics, artificial intelligence, and automation.     

Mek2 is dispensable for mouse growth and development

MEK is a dual-specificity kinase that activates the extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinase upon agonist binding to receptors. The ERK/MAP kinase cascade is involved in cell fate determination in many organisms. In mammals, this pathway is proposed to regulate cell growth and differentiation. Genetic studies have shown that although a single Mek gene is present in Caenorhabditis elegans, Drosophila melanogaster, and Xenopus laevis, two Mek homologs, Mek1 and Mek2, are present in the mammalian cascade. The inactivation of the Mek1 gene leads to embryonic lethality and has revealed the unique role played by Mek1 during embryogenesis. To investigate the biological function of the second homolog, we have generated mice deficient in Mek2 function. Mek2 mutant mice are viable and fertile, and they do not present flagrant morphological alteration. Although several components of the ERK/MAP kinase cascade have been implicated in thymocyte development, no such involvement was observed for MEK2, which appears to be nonessential for thymocyte differentiation and T-cell-receptor-induced proliferation and apoptosis. Altogether, our findings demonstrate that MEK2 is not necessary for the normal development of the embryo and T-cell lineages, suggesting that the loss of MEK2 can be compensated for by MEK1.     

Suppressor of Cytokine Signaling (SOCS) 5 Utilises Distinct Domains for Regulation of JAK1 and Interaction with the Adaptor Protein Shc-1

Suppressor of Cytokine Signaling (SOCS)5 is thought to act as a tumour suppressor through negative regulation of JAK/STAT and epidermal growth factor (EGF) signaling. However, the mechanism/s by which SOCS5 acts on these two distinct pathways is unclear. We show for the first time that SOCS5 can interact directly with JAK via a unique, conserved region in its N-terminus, which we have termed the JAK interaction region (JIR). Co-expression of SOCS5 was able to specifically reduce JAK1 and JAK2 (but not JAK3 or TYK2) autophosphorylation and this function required both the conserved JIR and additional sequences within the long SOCS5 N-terminal region. We further demonstrate that SOCS5 can directly inhibit JAK1 kinase activity, although its mechanism of action appears distinct from that of SOCS1 and SOCS3. In addition, we identify phosphoTyr317 in Shc-1 as a high-affinity substrate for the SOCS5-SH2 domain and suggest that SOCS5 may negatively regulate EGF and growth factor-driven Shc-1 signaling by binding to this site. These findings suggest that different domains in SOCS5 contribute to two distinct mechanisms for regulation of cytokine and growth factor signaling.     

Multicompartmental distribution of the tuberous sclerosis gene products,hamartin and tuberin

Mutations of the TSC1 and TSC2 genes give rise to the clinical disorder of tuberous sclerosis characterized by the development of hamartomas predominantly affecting the central nervous system, kidney, skin, lung, and heart. The function of the gene products, hamartin and tuberin, is not well understood but we have previously suggested a role in vesicular transport. To define the subcellular compartment(s) involved with these two proteins, biochemical characterization of hamartin and tuberin was performed in primary tissues and cell lines. Fractionation of cell lysates identified both proteins in the cytosolic, microsomal, and cytoskeletal compartments. In each of these fractions, hamartin and tuberin formed a stable complex in coimmunoprecipitation analyses. Further, they colocalized extensively in discrete, vesicular structures in the cytoplasm. Within the microsomal compartment, hamartin and tuberin behaved as peripheral membrane proteins that associate with the cytosolic leaflet of membranous domains. Immunoisolation of tuberin-bound vesicles using magnetic beads showed an enrichment of rap1, rab5, and caveolin-1, all of which have been found in specialized lipid microdomains, caveolae. Our data suggest that hamartin and tuberin are multicompartmental proteins that partially reside in caveolin-1-enriched structures and potentially affect their signaling.     

Comparison of LDH-B4 allozymes of macrourids (Teleostei: Gadiformes) by electrophoresis and peptide mapping

The heart-type lactate dehydrogenase (LDH-_B4) homologs of two species of Nezumia and eight species of Coryphaenoides are isomobile on two commonly used electrophoretic buffer systems. To test the hypothesis that the homologs possess the same primary structures, the allozymes from N. bairdii and four species of Coryphaenoides were purified by affinity chromatography on an oxamate aminohexyl Sepharose column and digested with trypsin. The resulting peptide mixtures were then mapped using reversed-phase high-performance liquid chromatography. The peptide maps of the enzyme homologs indicate that the overall similarity of the homologs is high, but unique peptides in each species indicate that the allozymes are not identical in primary structure.