Characterization of the degradation of wild-type and mutant HFE proteins during stress signalling in the endoplasmic reticulum

HFE is a transmembrane protein that becomes N-glycosylated during transport to the cell membrane. It acts to regulate cellular iron uptake by interacting with the Type 1 transferrin receptor and interfering with its ability to bind iron-loaded transferrin. There is also evidence that HFE regulates systemic iron levels by binding to the Type II transferrin receptor although the mechanism by which this occurs is still not well understood. Mutations to HFE that disrupt this function, or physiological conditions that decrease HFE protein levels, are associated with increased iron uptake, and its accumulation in tissues and organs. This is exemplified by the point mutation that results in conversion of cysteine residue 282 to tyrosine (C282Y), and gives rise to the majority of HFE-related hemochromatoses. The C282Y mutation prevents the formation of a disulfide bridge and disrupts the interaction with its co-chaperone β2-microglobulin. The resulting misfolded protein is retained within the endoplasmic reticulum (ER) where it activates the Unfolded Protein Response (UPR) and is subjected to proteasomal degradation. The absence of functional HFE at the cell surface leads to unregulated iron uptake and iron loading. While the E3 ubiquitin ligase involved in the degradation of HFE-C282Y has been identified, the mechanism by which it is targeted for degradation remains relatively obscure. The primary objective of this project was to further our understanding of how the iron regulatory HFE protein is targeted for degradation. Our studies suggest that the glycosylation status, and the active process of deglycosylation, are central to this process. We identified a number of additional factors that can contribute towards degradation and explored their regulation during ER stress conditions.

Echoes of existentialism in the works of Carlos Fuentes

In this thesis I have set out to trace the echoes of existentialism in the work of the Mexican novelist, Carlos Fuentes scrutinizing, in particular, La región más transparente, La muerte de Artemio Cruz and Cambio de piel. In the opening segment of the thesis I outline the essential tenets of existentialist thought and how it became the predominant philosophical and literary movement of the early part of the twentieth-century. Stemming from the work of Sören Kierkegaard in Denmark towards the end of the nineteenth-century, it challenged the arid philosophies of previous generations and provided a new way of looking at man and the human condition. In this opening chapter, I study the works of the more important philosophers in this regard such as Heidegger, Sartre, Jaspers, Marcel, Unamuno, and Ortega y Gasset and show how each in his own way contributed to the further development of the new philosophy. Chapter 2 is concerned with the spread of existentialism to the Latin American continent. In the early part of the twentieth-century, Mexico was emerging from a turbulent revolutionary period and seeking a solution to the fractured nature of its society. The Spanish philosopher, Ortega y Gasset, and the many Spanish intellectuals who sought refuge from Franco’s dictatorship in Mexico, helped to popularise the new philosophy and these lively debates about existentialism served to underpin ideas around mexicanidad or Mexican national identity. Carlos Fuentes was deeply immersed in the debate of his time, positioned as he was as a prominent public intellectual. In La muerte de Artemio Cruz he shows us how great wealth and power are a poor recompense for the loss of love and compassion and lead only to alienation and selfishness. In his other best known novel, La región más transparente, he explores the rise of modern Mexico and its society – an inauthentic society that is corrupted by a scramble for wealth and self-aggrandizement. The final chapter is devoted to the study of Cambio de piel which is concerned with violence and alienation as central pillars of existence. The violence depicted here precipitates a crisis in the human condition and an accompanying sense of alienation. The thesis seeks to establish that existentialism is central not only to Fuentes’s literary concerns but also forms a part of his ethics as an artist.