Uses for JNK: the many and varied substrates of the c-Jun N-terminal kinases

The c-Jun N-terminal kinases (JNKs) are members of a larger group of serine/ threonine (Ser/Thr) protein kinases from the mitogen-activated protein kinase family. JNKs were originally identified as stress-activated protein kinases in the livers of cycloheximide-challenged rats. Their subsequent purification, cloning, and naming as JNKs have emphasized their ability to phosphorylate and activate the transcription factor c-Jun. Studies of c-Jun and related transcription factor substrates have provided clues about both the preferred substrate phosphorylation sequences and additional docking domains recognized by JNK There are now more than 50 proteins shown to be substrates for JNK These include a range of nuclear substrates, including transcription factors and nuclear hormone receptors, heterogeneous nuclear ribonucleoprotein K and the Pol I-specific transcription factor TIF-IA, which regulates ribosome synthesis. Many nonnuclear substrates have also been characterized, and these are involved in protein degradation (e.g., the E3 ligase Itch), signal transduction (e.g., adaptor and scaffold proteins and protein kinases), apoptotic cell death (e.g., mitochondrial Bcl2 family members), and cell movement (e.g., paxillin, DCX, microtubule-associated proteins, the stathmin family member SCG10, and the intermediate filament protein keratin 8). The range of JNK actions in the cell is therefore likely to be complex. Further characterization of the substrates of JNK should provide clearer explanations of the intracellular actions of the JNKs and may allow new avenues for targeting the JNK pathways with therapeutic agents downstream of JNK itself.

The motor neurite terminal determines where neuromuscular synapses form in the absence of agrin

Agrin is a proteoglycan secreted by motor neurite terminals that functions to initiate and maintain AChR clusters at the nerve terminal. This led to the theory that neurite terminals decide where neuromuscular synapses form by secreting agrin. However, initiation of AChR clustering occurs in the absence of the innervating motoneuron and in the absence of agrin. In this instance, the muscle, not the nerve, is deciding the location of neuromuscular synapses by drawing neurite terminals towards pre-existing AChR clusters. If this were true, one would expect the initial innervation patterns to be the same in agrin-deficient mice and wild-type mice. To test this we quantified the intramuscular axonal branching and synapse formation in the diaphragm at E14.5 in agrin-deficient mice and wild-type mice. Heterozygote mothers were anaesthetised with Nembutal (30 mg) and killed via cervical dislocation. In the diaphragm, the nerve trunk runs down the centre of the muscle and extends branches primarily toward the lateral side. In agrin-deficient mice however, we found significantly more branches exited the phrenic nerve trunk, branched in the periphery and extended further on the medial side. Moreover, we found that the percentage α-bungarotoxin/synaptophysin colocalisations, markers of pre- and postsynaptic differentiation, respectively, was the same in agrin-deficient mice and wild-type mice. These results show that initial innervation patterns are not the same in agrin-deficient mice and wild-type mice indicating neurite terminals, not muscle, decide the placement of neuromuscular synapses in the absence of agrin.

A regulatory domain in the C-terminal extension of the yeast glycerol channel Fps1p

The Saccharomyces cerevisiae gene FPS1 encodes an aquaglyceroporin of the major intrinsic protein (MIP) family. The main function of Fps1p seems to be the efflux of glycerol in the adaptation of the yeast cell to lower external osmolarity. Fps1p is an atypical member of the family, because the protein is much larger (669 amino acids) than most MIPs due to long hydrophilic extensions in both termini. We have shown previously that a short domain in the N-terminal extension of the protein is required for restricting glycerol transport through the channel (Tamás, M. J., Karlgren, S., Bill, R. M., Hedfalk, K., Allegri, L., Ferreira, M., Thevelein, J. M., Rydström, J., Mullins, J. G. L., and Hohmann, S. (2003) J. Biol. Chem. 278, 6337-6345). Deletion of the N-terminal domain results in an unregulated channel, loss of glycerol, and osmosensitivity. In this work we have investigated the role of the Fps1p C terminus (139 amino acids). A set of eight truncations has been constructed and tested in vivo in a yeast fps1Δ strain. We have performed growth tests, membrane localization following cell fractionation, and glycerol accumulation measurements as well as an investigation of the osmotic stress response. Our results show that the C-terminal extension is also involved in restricting transport through Fps1p. We have identified a sequence of 12 amino acids, residues 535-546, close to the sixth transmembrane domain. This element seems to be important for controlling Fps1p function. Similar to the N-terminal domain, the C-terminal domain is amphiphilic and has a potential to dip into the membrane.

Industrial relations in the road passenger transport industry-a political-economic analysis.

This thesis examines the British Bus and Tram Industry from 1889 to 1988. The first determinant of the pattern of industrial relations is the development of the labour-process. The labour process changes with the introduction of new technology (electrified trams and mechanised buses), the concentration and centralisation of ownership, the decline of competition, changing market position, municipal and state regulation, ownership and control. The tram industry, as a consequence of electrification, is almost wholly municipally owned and the history of the labour process from horse-trams to the decline of the industry is examined. The bus industry has a less unified structure and is examined by sector; London, Municipal, and Territorial/Provincial. The small independent sector is largely ignored. The labour process is examined from the horse-bus to the present day. The development of resistance in the labour process is discussed both as a theoretical problematic (the `Braverman Debate') and through the process of unionisation, the centralisation and bureaucratisation of the unions, the development of national bargaining structures (National Joint Industrial Council and the National Council for the Omnibus Industry), and the development of resistance to those processes. This resistance takes either a syndicalist form, or under Communist Party leadership the form of rank and file movements, or simply unofficial organisations of branch officials. The process of centralisation of the unions, bureaucratisation and the institutionalisation of bargaining and the relationship between this process and the role of the Unions in the Labour Party is examined. Neo-corporatism, that is the increasing integration of the leadership of the main Union, the T.G.W.U.with the Labour Party and with the State is discussed. In theoretical terms, this thesis considers the debate around the notion of `labour process', the relationship between labour process and labour politics and between labour process and labour history. These relationships are placed within a discussion of class consciousness.

The development of an in vivo model of drug-induced terminal differentiation of Leukaemic cells

The technique of growing human leukaemic cells in diffusion chambers was developed to enable chemicals to be assessed for their ability to induce terminal differentiation. HL-60 promyelocytic leukaemia cell growth, in a lucite chamber with a Millipore filter, was optimised by use of a lateral incision site. Chambers were constructed using 0.45um filters and contained 150ul of serum-free HL-60 cells at a density of 1x106 cells/ml. The chambers were implanted into CBA/Ca mice and spontaneous terminal differentiation of the cells to granulocytes was prevented by the use of serum-free medium. Under these conditions there was an initial growth lag of 72 hours and a logarithmic phase of growth for 96 hours; the cell number reached a plateau after 168 hours of culture in vivo. The amount of drug in the plasma of the animal and in chambers that had been implanted for 5 days, was determined after a single ip injection of equitoxic doses of N-methylformamide, N-ethylformamide, tetramethylurea, N-dibutylformamide, N-tetramethylbutylformamide and hexamethylenebisacetamide. Concentrations of both TMU and HMBA were obtained in the plasma and in the chamber which were pharmacologically effective for the induction of differentiation of HL-60 cells in vitro, that is 12mM TMU and 5mM HMBA. A 4 day regime of treatment of animals implanted with chambers demonstrated that TMU and HMBA induced terminal differentiation of 50% and 35%, respectively, of the implanted HL-60 cells to granulocyte-like cells, assessed by measurement of functional and biochemical markers of maturity. None of the other agents attained concentrations in the plasma that were pharmacologically effective for the induction of differentiation of the cells in vitro and were unable to induce the terminal differentiation of the cells in vivo.

The influence of political, economic and passenger market factors on international civil aviation

Civil aviation plays an essential role in maintaining international communications. Many extraneous factors influence the daily operations of the air transport industry. This thesis begins by investigating the major categories of so­ called "external interests" in civil aviation. These are shown to have played a significant part in ensuring the need for international agreement over the adoption of regulating principles. The combination and interaction of the various influences has produced a particular type of regulatory environment in which all commercial air services have to operate. The need for such regulation and the extreme difficulty experienced in trying to define universally acceptable methods of supervision is discussed. It is shown how opportunity for the development of on-scheduled air services was created by default on the part of the European Governments.The concept of so-called "scheduled" and "non-scheduled" sectors" is considered and it is suggested that growth of the inclusive tour industry resulted from inappropriate categorisation of the air services involved. The means by which development opportunities were created for inclusive tour operations is considered and the work then investigates the importance of British air transport policy in their exploitation. The politics of British civil aviation in the post-war years is the subject of detailed examination and the process by which Independent airlines were encouraged to develop inclusive tours, is identified. This theme is expanded to demonstrate the vital contribution of British air transport policy in the restructuring of the international industry. The subsequent involvement of the United States is shown to have been directed specifically towards the satisfaction of domestic issues. British objectives, however, are considered to have been more generally concerned with improving the tariff structure. The unique opportunities for British experimentation with international fares are seen to have major influence in forcing the pace of tariff rationalisation.

Attenuation of muscle atrophy by an N-terminal peptide of the receptor for proteolysis-inducing factor (PIF)

Background: Atrophy of skeletal muscle in cancer cachexia has been attributed to a tumour-produced highly glycosylated peptide called proteolysis-inducing factor (PIF). The action of PIF is mediated through a high-affinity membrane receptor in muscle. This study investigates the ability of peptides derived from the 20 N-terminal amino acids of the receptor to neutralise PIF action both in vitro and in vivo. Methods: Proteolysis-inducing factor was purified from the MAC16 tumour using an initial pronase digestion, followed by binding on DEAE cellulose, and the pronase was inactivated by heating to 80°C, before purification of the PIF using affinity chromatography. In vitro studies were carried out using C2C12 murine myotubes, while in vivo studies employed mice bearing the cachexia-inducing MAC16 tumour. Results: The process resulted in almost a 23?000-fold purification of PIF, but with a recovery of only 0.004%. Both the D- and L-forms of the 20mer peptide attenuated PIF-induced protein degradation in vitro through the ubiquitin-proteosome proteolytic pathway and increased expression of myosin. In vivo studies showed that neither the D- nor the L-peptides significantly attenuated weight loss, although the D-peptide did show a tendency to increase lean body mass. Conclusion: These results suggest that the peptides may be too hydrophilic to be used as therapeutic agents, but confirm the importance of the receptor in the action of the PIF on muscle protein degradation.

Terminal galactose residues on transferrin are increased in mid-life adults compared to young adults

Humans undergo biological ageing at different rates. This associates with functional decline in a number of physiological systems and increasing incidence of age-related pathologies. The discovery of robust biomarkers of ageing could be used to identify early divergence from a path of healthy ageing towards age-related disease. In the present study, we undertook proteomic analysis of plasma from healthy young men (mean age = 21.4 ± 1.5 years) and healthy mid-life men (mean age = 57.0 ±1.6 years). We identified twelve spots including transferrin, complement C3b and transthyretin that differed in abundance between the age groups. Transferrin spots showed an acidic pI shift in older males. Sandwich ELISAs were used to investigate the changes further. C3b levels were below the level of detection by ELISA and plasma concentrations of total transferrin or transthyretin were not different between the age groups studied here. However, analysis of transferrin N-glycan structures showed an increase in terminal galactose residues in older men, suggesting that the loss of terminal N-acetyl neuraminic acid residues contributes to the more acid pI of transferrin spots observed with age. Terminal galactosylation of transferrin may be a biomarker of healthy ageing and is now under investigation in the MARKAGE study.

The effect of growth conditions on the synthesis of Pseudomonas aeruginosa terminal oxidase.

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