The histology of the bovine liver with special reference to the formation of bile canaliculi

Call number: LD2668 .T4 1959 M3

Typing of methicillin resistant and sensitive Staphylococcus aureus isolated from Tamilnadu, India using DNA fingerprints by pulsed-field gel electrophoresis

MRSA infection is alarming particularly in hospital set ups/community. We typed 43 isolates of Staphylococcus aureus (MRSA and MSSA) based on genomic DNA restriction fragment length polymorphisms (RFLPs). The genomic DNA of the test isolates was digested with SmaI enzyme, fractionated by PFGE and the patterns were assessed by dendrogram for percentage similarity. The SmaI restricted genomic DNA of 19 MRSA and 24 MSSA identified 27 different PFGE patterns, in which 11 and 16 were from MRSA and MSSA, respectively. Prevalence predominance was observed in few types/subtypes of MSSA (type B and subtype I-1) and MRSA (sub type A-2) and high percentage of similarity was noticed among the subtypes of PFGE types such as P and I of MSSA. During the epidemiological studies, to understand the dissemination of endemic/epidemic MRSA and MSSA, PFGE-based typing of pathogens may be used as a reliable and effective typing method

Dual functionality of <i>O</i>-GlcNAc transferase is required for <i>Drosophila </i>development

Post-translational modification of intracellular proteins with O-linked N-acetylglucosamine (O-GlcNAc) catalysed by O-GlcNAc transferase (OGT) has been linked to regulation of diverse cellular functions. OGT possesses a C-terminal glycosyltransferase catalytic domain and N-terminal tetratricopeptide repeats that are implicated in protein–protein interactions. Drosophila OGT (DmOGT) is encoded by super sex combs (sxc), mutants of which are pupal lethal. However, it is not clear if this phenotype is caused by reduction of O-GlcNAcylation. Here we use a genetic approach to demonstrate that post-pupal Drosophila development can proceed with negligible OGT catalysis, while early embryonic development is OGT activity-dependent. Structural and enzymatic comparison between human OGT (hOGT) and DmOGT informed the rational design of DmOGT point mutants with a range of reduced catalytic activities. Strikingly, a severely hypomorphic OGT mutant complements sxc pupal lethality. However, the hypomorphic OGT mutant-rescued progeny do not produce F2 adults, because a set of Hox genes is de-repressed in F2 embryos, resulting in homeotic phenotypes. Thus, OGT catalytic activity is required up to late pupal stages, while further development proceeds with severely reduced OGT activity

Intellectual disability-associated disruption of O-GlcNAcylation impairs neuronal development and cognition-relevant habituation learning in Drosophila

O-GlcNAcylation is a reversible co-/post-translational modification involved in a multitude of cellular processes. The addition and removal of the O-GlcNAc modification is controlled by two conserved enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (OGA). Mutations in OGT have recently been discovered to cause a novel Congenital Disorder of Glycosylation (OGT-CDG) that is characterized by intellectual disability. The mechanisms by which OGT-CDG mutations affect cognition remain unclear. We manipulated O-GlcNAc transferase and O-GlcNAc hydrolase activity in Drosophila and demonstrate an important role of O-GlcNAcylation in habituation learning and synaptic development at the larval neuromuscular junction. Introduction of patient-specific missense mutations into Drosophila O-GlcNAc transferase using CRISPR/Cas9 gene editing leads to deficits in locomotor function and habituation learning. The habituation deficit can be corrected by blocking O-GlcNAc hydrolysis, indicating that OGT-CDG mutations affect cognition-relevant habituation via reduced protein O-GlcNAcylation. This study establishes a critical role for O-GlcNAc cycling and disrupted O-GlcNAc transferase activity in cognitive dysfunction, and suggests that blocking O-GlcNAc hydrolysis is a potential strategy to treat OGT-CDG

The Future Perspectives of Drug Repurposing and Treatment for the Drug Resistant Breast Cancer: A Review

Breast cancer is a major health concern as it is the second leading cause of death from cancer. There are several well-known risk factors that contribute to breast cancer. Despite the various treatment options available, complete cure is still difficult due to heterogenicity of BC subtypes. As a result, identifying BC subtypes is critical for determining the optimal treatment approach. Over the last several years, new drugs targeting particular therapeutic targets have resulted in significant advances in the treatment of breast cancer. Nonetheless, resistance to treatment is the “major” issue, and a significant increase in survival rates has been the main focus for researchers. The purpose of this review article is to provide a broad overview of the molecular basis of drug resistance in breast cancer, as well as a detailed assessment of current treatment options, potential new treatment methods for drug-resistant breast cancer and repurposed drugs used for treatment. The possibility of non-cancer drugs being studied for breast cancer in the future, as well as the obstacles and bottlenecks of drug repurposing, is also highlighted. Finally, we go through present problems and future prospects in drug-resistant breast cancer therapy

Importance of Protein Kinase and Its Inhibitor: A Review

Deregulation of a broad range of protein kinases has been linked to the development and growth of cancer cells. Protein kinases are intracellular enzymes that regulate cell growth and proliferation as well as the triggering and regulation of immune responses. Protein kinases are important therapeutic targets in cancer because of their critical role in signalling mechanisms that drive malignant cell characteristics. Intensive efforts in drug research have been made in this area over the last two decades. The current study delves into the catalytic domain of a protein kinase as well as information transfer from the cell’s membrane to internal targets. It also discusses the function of protein kinases in signal transduction and their cellular signalling pathways. Furthermore, it specifically outlines a systematic method to hybrid therapies to solve the issue of protein kinase resistance. The therapeutic use of nitric oxide, as well as other targets such as Phosphoinositide 3-kinases (PI3K), Protein Kinase B (Akt), serine/threonine protein kinase (mTOR), p38 mitogen-activated protein kinases (p38 MAPK), vascular endothelial growth factor receptors (VEGFR), epidermal growth factor receptors (EGFR), and anaplastic lymphoma (ALK) etc., According to the review article, selective therapy has shown high effectiveness in the treatment of advanced cancer, with protein kinase inhibitors being a main focus of the therapy. As a result, the latest review summarized that, the current state of science with the aim of identifying a novel protein kinase inhibitor that may be utilized in the treatment of advanced cancers

A mutant O-GlcNAcase enriches Drosophila developmental regulators

YesProtein O-GlcNAcylation is a reversible post-translational modification of serines/threonines on nucleocytoplasmic proteins. It is cycled by the enzymes O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (O-GlcNAcase or OGA). Genetic approaches in model organisms have revealed that protein O-GlcNAcylation is essential for early embryogenesis. Drosophila melanogaster OGT/supersex combs (sxc) is a polycomb gene, null mutants of which display homeotic transformations and die at the pharate adult stage. However, the identities of the O-GlcNAcylated proteins involved, and the underlying mechanisms linking these phenotypes to embryonic development, are poorly understood. Identification of O-GlcNAcylated proteins from biological samples is hampered by the low stoichiometry of this modification and limited enrichment tools. Using a catalytically inactive bacterial O-GlcNAcase mutant as a substrate trap, we have enriched the O-GlcNAc proteome of the developing Drosophila embryo, identifying, amongst others, known regulators of Hox genes as candidate conveyors of OGT function during embryonic development.Wellcome Trust Investigator Award (110061); MRC grant (MC_UU_12016/5); and Royal Society Research Grant

Nucleocytoplasmic human O-GlcNAc transferase is sufficient for O-GlcNAcylation of mitochondrial proteins

O-linked N-acetylglucosamine modification (O-GlcNAcylation) is a nutrient-dependent protein post-translational modification (PTM), dynamically and reversibly driven by two enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) that catalyse the addition and the removal of the O-GlcNAc moieties to/from serine and threonine residues of target proteins respectively. Increasing evidence suggests involvement of O-GlcNAcylation in many biological processes, including transcription, signalling, neuronal development and mitochondrial function. The presence of a mitochondrial O-GlcNAc proteome and a mitochondrial OGT (mOGT) isoform has been reported. We explored the presence of mOGT in human cell lines and mouse tissues. Surprisingly, analysis of genomic sequences indicates that this isoform cannot be expressed in most of the species analysed, except some primates. In addition, we were not able to detect endogenous mOGT in a range of human cell lines. Knockdown experiments and Western blot analysis of all the predicted OGT isoforms suggested the expression of only a single OGT isoform. In agreement with this, we demonstrate that overexpression of the nucleocytoplasmic OGT (ncOGT) isoform leads to increased O-GlcNAcylation of mitochondrial proteins, suggesting that ncOGT is necessary and sufficient for the generation of the O-GlcNAc mitochondrial proteome