The role of keratin intermediate filaments in the colon epithelial cells

Keratins (K) are cytoskeletal proteins mainly expressed in the epithelium and constitute the largest subgroup of intermediate filaments (IFs). Simple epithelial keratins (SEKs) K7-K8 and K18-K20 are the major IF elements in the colon. SEK mutations are known to cause around 30 human diseases, mainly affecting liver and skin. However, so far no strong associations between K8 mutations and the development of human colitis have been found. The keratin contribution to colonic health comes from the K8 knock-out (K8-/-) mouse model, which develops an early chronic inflammation and hyperproliferation in the colon. The aim of this thesis was to investigate how keratins contribute to intestinal health and disease mainly by the experimental analysis using the K8-/- mouse colon and cell culture models. The work described here is divided into three studies. The first study revealed involvement of keratins in Notch1 signaling, which is the master regulator of cell fate in the colon. Immunoprecipitation and immunostaining, both in vitro and in vivo showed that K8 binds and co-localizes with Notch1. Interestingly, overexpression of keratins enhanced Notch1 levels and stabilized Notch intracellular domain (NICD), leading to higher activity of Notch signaling. The dramatic decrease in Notch activity in the K8-/- colon resulted in a differentiation shift towards goblet and enteroendocrine cells. The second study focused on the involvement of keratins in colitis-associated cancer (CAC). Although, the K8-/- inflamed colon did not develop colorectal cancer (CRC) spontaneously, it was dramatically more susceptible to induced CRC in two CRC models: azoxymethane (AOM) and multiple intestinal neoplasia (ApcMin/+). To understand how the loss of K8 contributes to CAC, the epithelial inflammasome signaling pathway was analyzed. The released component of active inflammasome, cleaved caspase-1 and its downstream protein, interleukin (IL)-18, were significantly increased in K8-/- and K8-/-ApcMin/+ colons. The inflammasome pathway has recently been suggested to control the levels of IL-22 binding protein (IL-22BP), which is a negative regulator of IL-22 activity. Interestingly, the activated inflammasome correlated with an upregulation of IL-22 and a complete loss of IL-22BP in the K8-null colons. The activation of IL-22 was confirmed by increased levels of downstream signaling, which is phosphorylated signal transducer and activator of transcription 3 (P-STAT3), a transcription factor promoting proliferation and tissue regeneration in the colon. The objective of the third study, was to examine the role of keratins in colon energy metabolism. A proteomic analysis identified mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) as the major ownregulated protein in the K8-/- colonocytes. HMGCS2 is the rate-limiting enzyme in ketogenesis, where energy from bacterially produced short chain fatty acids (SCFAs), mainly butyrate, is converted into ketone bodies in colonic epithelium. Lower levels and activity of HMGCS2 in the K8-/- colon resulted in a blunted ketogenesis. The studies upstream from HMGCS2, identified decreased levels of the SCFA-transporter monocarboxylate transporter 1 (MCT1), which led to increased SCFA content in the stool suggesting impaired butyrate transport through the colonic epithelium. Taken together, the results of the herein thesis indicate that keratins are essential regulators of colon homeostasis, in particular epithelial differentiation, tumorigenesis and energy metabolism.

I volontari italiani nelle Waffen-SS. Il pensiero politico, la formazione culturale e le motivazioni al volontariato. Una storia orale

My doctoral dissertation examines the experiences of the Italian volunteers in the Waffen-SS troops using in-depth interviews with former volunteers as the main primary source. This phenomenon, even if significant in size (depending on the source, some 15 000-20 000 Italian men volunteered in the Waffen-SS), has been hitherto largely unknown to historical research. The available literature on the Italian volunteers, mainly written by military history enthusiast journalists and methodologically weak, concentrates mainly on the combat operations and military organization, and offers a rather stereotypical profile of the volunteers. My dissertation does not aim to reconstruct the military history of the different divisions of the Waffen-SS in which Italian volunteers operated but instead to examine the subjective, private and intimate experience of the volunteers in order to understand the motivations, attitudes, beliefs and cultural and family background, as well as their political ideas. The main objective of my doctoral dissertation is to discover the ideological precepts of the volunteers’ political credo. As the last phase of fascism and its ideology, often defined as the “Germanisation” or “Nazification” of fascism, is still the object of wide academic debate, a better understanding of the volunteers’ ideology also contributes to deepening overall knowledge of the nature of this last phase. The theoretical frame of my dissertation lies in oral history, in particular in the postmodernist approach to oral history, through which I reconstruct the volunteers’ ideology. In-depth interviews with former volunteers are the main primary source, but multiple data collection methods have been adopted. Phone interviews and correspondence with the volunteers have also been considered as primary sources. In addition to interviews and correspondence, family archives consisting of diaries, correspondence with the volunteers’ relatives and photographic material have also been collected and examined. An ethnographic observation of the volunteers’ domestic spaces has been conducted during the in-depth interviews, and photo self-elicitation techniques have been used in cases where the volunteers were willing to share their photographs. An exhaustive portrait of the ideological structure of the volunteers has been obtained, as well as of the cultural and social origins of the values that contributed to the rise and adoption of this ideology. Further, the volunteers’ motivations to enlist have been clearly reconstructed, together with their cultural, political, social and military backgrounds. The results of the research are particularly relevant both for comprehension of the Italian phenomenon of volunteering in the Waffen-SS and for the reconstruction of the ideological dynamics of the last phase of fascism. The volunteers’ political and ideological system, which can be defined as the Italian SS-fascist ideology, disagrees strongly with the vaguely described ideological profile offered by previous studies that describe volunteers as generically “super-fascist”. The research also offers the opportunity for a deeper understanding of the final fascist ideological trajectory, currently defined, not without a certain level of approximation, as the “Germanisation” or “Nazification” of fascist ideology.

Ce gu'il fant savoir de la Finlande

kuv., 9 x 12 cm