This project will investigate phosphorylation of keratin intermediate filaments as a mechanism for keratin filament disorganization in alcoholic hepatitis. Preliminary data have shown that (1) disorganization of keratin filaments in chemically treated cells is directly correlated with reduced phosphorylation of keratin polypeptides and that (2) liver keratins isolated from ethanol-fed rats show significant reduction in phosphorylation levels. Preliminary data also show that changes in keratin phosphorylation result in conformational changes in the protein. NMR spectroscopy will be used to identify phosphorylation sites on liver keratins 8 and 18 (K8/18) which display altered phosphorylation levels in alcoholic hepatitis. This information will be used to induce site-specific changes in K8/18 phosphorylation for analysis of conformational change. Effects of phosphorylation on keratin structure will be analyzed by employing techniques sensitive to protein structure and dynamics in both the end domains and in the rod domains of the keratins. Keratins labelled with the stable, NMR sensitive isotopes, 13C and 2H, in the end domains will be used to monitor their structure and dynamics, as a function of phosphorylation. 31P NMR will be used to monitor the immediate environments of the phosphorylation sites. To probe for effects of phosphorylation on the rod domains as a function of specific phosphorylation, circular dichroism (CD), reporting on the helix in the rod domains, and tryptophan fluorescence, arising exclusively from the rod domains, will be employed. These studies will provide a systematic analysis of the relationship between keratin phosphorylation and organization of keratin filaments in alcoholic hepatitis and will be the first to provide correlation between the effects of phosphorylation on keratin structure and organization in a pathological state.
| Negron, G; Eckert, B S (2000) Role of phosphorylation in ethanol-induced aggregation of keratin intermediate filaments. Alcohol Clin Exp Res 24:1343-52 |
| Sanhai, W R; Eckert, B S; Yeagle, P L (1999) Altering the state of phosphorylation of rat liver keratin intermediate filaments by ethanol treatment in vivo changes their structure. Biochim Biophys Acta 1429:459-66 |
| Eckert, B S; Yeagle, P L (1996) Site-specificity of ethanol-induced dephosphorylation of rat hepatocyte keratins 8 and 18: A 31P NMR study. Cell Motil Cytoskeleton 33:30-7 |
