Biochemical and proteomic characterization of alkaptonuric chondrocytes.

Abstract

Alkaptonuria (AKU) is a rare genetic disease associated with the accumulation of homogentisic acid (HGA) and its oxidized/polymerized products which leads to the deposition of melanin-like pigments (ochronosis) in connective tissues. Although numerous case reports have described ochronosis in joints, little is known on the molecular mechanisms leading to such a phenomenon. For this reason, we characterized biochemically chondrocytes isolated from the ochronotic cartilage of AKU patients. Based on the macroscopic appearance of the ochronotic cartilage, two sub-populations were identified: cells coming from the black portion of the cartilage were referred to as "black" AKU chondrocytes, while those coming from the white portion were referred to as "white" AKU chondrocytes. Notably, both AKU chondrocytic types were characterized by increased apoptosis, NO release, and levels of pro-inflammatory cytokines. Transmission electron microscopy also revealed that intracellular ochronotic pigment deposition was common to both "white" and "black" AKU cells. We then undertook a proteomic and redox-proteomic analysis of AKU chondrocytes which revealed profound alterations in the levels of proteins involved in cell defence, protein folding, and cell organization. An increased post-translational oxidation of proteins, which also involved high molecular weight protein aggregates, was found to be particularly relevant in "black" AKU chondrocytes.

• Authors: Daniela Braconi, Giulia Bernardini, Claretta Bianchini, Marcella Laschi, Lia Millucci, Loredana Amato, Laura Tinti, Tommaso Serchi, Federico Chellini, Adriano Spreafico, Annalisa Santucci
• Journal: Journal of cellular physiology (J Cell Physiol) Vol. 227 Issue 9 Pg. 3333-43 (Sep 2012) ISSN: 1097-4652 [Electronic] United States
• PMID: 22213341 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2011 Wiley Periodicals, Inc.

Chemical References

• Cytokines
• Proteome
• Nitric Oxide

Topics

• Aged
• Alkaptonuria (genetics, metabolism, pathology)
• Apoptosis (genetics)
• Cartilage (metabolism, pathology)
• Cell Proliferation
• Chondrocytes (metabolism, pathology)
• Cytokines (genetics, metabolism)
• Female
• Gene Expression Regulation
• Humans
• Male
• Microscopy, Electron, Transmission
• Middle Aged
• Nitric Oxide (metabolism)
• Ochronosis (genetics, metabolism, pathology)
• Oxidation-Reduction
• Pigmentation (genetics)
• Proteome (genetics, metabolism)