title: Keratins modulate the shape and function of hepatocyte mitochondria: a mechanism for protection from apoptosis.
abstract: Absence or mutation of keratins 8 (K8) or 18 (K18) cause predisposition to liver injury and apoptosis. We assessed the mechanisms of hepatocyte keratin-mediated cytoprotection by comparing the protein expression profiles of livers from wild-type and K8-null mice using two-dimensional differential-in-gel-electrophoresis (2D-DIGE) and mass spectrometry. Prominent among the alterations were those of mitochondrial proteins, which were confirmed using 2D-DIGE of purified mitochondria. Ultrastructural analysis showed that mitochondria of livers that lack or have disrupted keratins are significantly smaller than mitochondria of wild-type livers. Immunofluorescence staining showed irregular distribution of mitochondria in keratin-absent or keratin-mutant livers. K8-null livers have decreased ATP content; and K8-null mitochondria have less cytochrome c, increased release of cytochrome c after exposure to Ca(2+) and oxidative stimulation, and a higher sensitivity to Ca(2+)-induced permeability transition. Therefore, keratins play a direct or indirect role in regulating the shape and function of mitochondria. The effects of keratin mutation on mitochondria are likely to contribute to hepatocyte predisposition to apoptosis and oxidative injury, and to play a pathogenic role in keratin-mutation-related human liver disease.
authors.affiliation: Department of Surgery, Stanford University, Palo Alto, CA 94305, USA.
authors.forename: Guo-Zhong
authors.initials: GZ
authors.lastname: Tao
authors.forename: Kok Sun
authors.initials: KS
authors.lastname: Looi
authors.forename: Diana M
authors.initials: DM
authors.lastname: Toivola
authors.forename: Pavel
authors.initials: P
authors.lastname: Strnad
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhou
authors.forename: Jian
authors.initials: J
authors.lastname: Liao
authors.forename: Yuquan
authors.initials: Y
authors.lastname: Wei
authors.forename: Aida
authors.initials: A
authors.lastname: Habtezion
authors.forename: M Bishr
authors.initials: MB
authors.lastname: Omary
mesh_terms: D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology* / Q000378:metabolism*; D053538:Keratin-18 / Q000235:genetics / Q000378:metabolism*; D053533:Keratin-8 / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress
chemical_list: D053538:Keratin-18; D053533:Keratin-8; C486595:Krt8 protein, mouse; D045304:Cytochromes c