Protein kinase C, an enzyme that is activated by the receptor-mediated hydrolysis of inositol phospholipids, relays information in the form of a variety of extracellular signals across the membrane to regulate many Ca2+-dependent processes. At an early phase of cellular responses, the enzyme appears to have a dual effect, providing positive forward as well as negative feedback controls over various steps of its own and other signaling pathways, such as the receptors that are coupled to inositol phospholipid hydrolysis and those of some growth factors. In biological systems, a positive signal is frequently followed by immediate negative feedback regulation. Such a novel role of this protein kinase system seems to give a logical basis for clarifying the biochemical mechanism of signal transduction, and to add a new dimension essential to our understanding of cell-to-cell communication.

https://science.sciencemag.org/content/sci/233/4761/305.full.pdf

Studies and perspectives of protein kinase C

The reference human genome sequence set the stage for studies of genetic variation and its association with human disease, but epigenomic studies lack a similar reference. To address this need, the NIH Roadmap Epigenomics Consortium generated the largest collection so far of human epigenomes for primary cells and tissues. Here we describe the integrative analysis of 111 reference human epigenomes generated as part of the programme, profiled for histone modification patterns, DNA accessibility, DNA methylation and RNA expression. We establish global maps of regulatory elements, define regulatory modules of coordinated activity, and their likely activators and repressors. We show that disease- and trait-associated genetic variants are enriched in tissue-specific epigenomic marks, revealing biologically relevant cell types for diverse human traits, and providing a resource for interpreting the molecular basis of human disease. Our results demonstrate the central role of epigenomic information for understanding gene regulation, cellular differentiation and human disease.

Integrative analysis of 111 reference human epigenomes

Bacteria communicate with one another using chemical signal molecules. As in higher organisms, the information supplied by these molecules is critical for synchronizing the activities of large groups of cells. In bacteria, chemical communication involves producing, releasing, detecting, and responding to small hormone-like molecules termed autoinducers. This process, termed quorum sensing, allows bacteria to monitor the environment for other bacteria and to alter behavior on a population-wide scale in response to changes in the number and/or species present in a community. Most quorum-sensing-controlled processes are unproductive when undertaken by an individual bacterium acting alone but become beneficial when carried out simultaneously by a large number of cells. Thus, quorum sensing confuses the distinction between prokaryotes and eukaryotes because it enables bacteria to act as multicellular organisms. This review focuses on the architectures of bacterial chemical communication networks; how c...

/pdf/quorum-sensing-cell-to-cell-communication-in-bacteria-15ypp5joz7.pdf

QUORUM SENSING: Cell-to-Cell Communication in Bacteria

Physiological actions of taurine

Prostanoids are the cyclooxygenase metabolites of arachidonic acid and include prostaglandin (PG) D2, PGE2, PGF2α, PGI2, and thromboxne A2. They are synthesized and released upon cell stimulation and act on cells in the vicinity of their synthesis to exert their actions. Receptors mediating the actions of prostanoids were recently identified and cloned. They are G protein-coupled receptors with seven transmembrane domains. There are eight types and subtypes of prostanoid receptors that are encoded by different genes but as a whole constitute a subfamily in the superfamily of the rhodopsin-type receptors. Each of the receptors was expressed in cultured cells, and its ligand-binding properties and signal transduction pathways were characterized. Moreover, domains and amino acid residues conferring the specificities of ligand binding and signal transduction are being clarified. Information also is accumulating as to the distribution of these receptors in the body. It is also becoming clear for some types of ...

/pdf/prostanoid-receptors-structures-properties-and-functions-39b6l6xzxf.pdf

Prostanoid Receptors: Structures, Properties, and Functions

Suprachiasmatic nucleus : the mind's clock

Prostaglandins (PG’s) stimulated resorption of fetal rat bone in 48–96 hr tissue culture. The effects of several PG’s were compared to the stimulation of bone resorption caused by parathyroid hormone (PTH). PGE1 and PGE2 caused increased release of previously incorporated radioactive calcium into the medium, losses of stable and labeled Ca from the bone and morphologic changes of osteoclastic resorption at 10−5-10−8M. The effects of PGE1 and PGE2 were similar to those of PTH (10−7- 10−8M) but in some experiments the effects of maximal doses of PTH were larger at 48 hr. Like PTH, the effects of PGE1 were inhibited by thyrocalcitonin and cortisol. PGA1 and PGFlα also stimulated bone resorption but only at higher doses (10−5M). In vivo studies demonstrated that injections of PGE1 in parathyroidectomized rats did not increase serum calcium concentration, while parathyroid extract (4–40 U/rat) was effective. (Endocrinology 86: 1436, 1970)

Prostaglandins: Stimulation of Bone Resorption in Tissue Culture

The activity of N-acetyltransferase in the rat pineal gland is more than 15 times higher at night than during the day. This circadian rhythm persists in complete darkness, or in blinded animals, and is suppressed in constant lighting. The N-acetyltransferase rhythm is 180 degrees out of phase with the serotonin rhythm and is similar to the norepinephrine and melatonin rhythms. Experiments in vitro indicate that norepinephrine, not serotonin, regulates the activity of N-acetyl-transferase through a highly specific receptor.

https://science.sciencemag.org/content/sci/169/3950/1093.full.pdf

David C. Klein

Papers

Suprachiasmatic nucleus : the mind's clock

Prostaglandins: Stimulation of Bone Resorption in Tissue Culture

Indole Metabolism in the Pineal Gland: A Circadian Rhythm in N-Acetyltransferase

Visual pathways and the central neural control of a circadian rhythm in pineal serotonin N-acetyltransferase activity

Pineal N-acetyltransferase and hydroxyindole-O-methyltransferase: control by the retinohypothalamic tract and the suprachiasmatic nucleus.