HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hawse, J. R. Articles by Kantorow, M. Search for Related Content PubMed PubMed Citation Articles by Hawse, J. R. Articles by Kantorow, M.

Activation of Metallothioneins and -Crystallin/sHSPs in Human Lens Epithelial Cells by Specific Metals and the Metal Content of Aging Clear Human Lenses

¹From the Department of Biology, West Virginia University, Morgantown, West Virginia; and the ²Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan.

PURPOSE. To identify those metallothionein and -crystallin/small heat-shock genes induced by toxic metals in human lens cells and to evaluate the levels of these metals between young and aged human lenses.

METHODS. Human SRA01/04 and primary human lens epithelial cells were cultured and exposed to Cd²⁺, Cu²⁺, and Zn²⁺. The levels of lens metallothioneins (Ig, If, Ih, Ie, and IIa) and -crystallin/small heat-shock (A-crystallin, B-crystallin, and HSP27) genes were analyzed by semiquantitative and quantitative competitive RT-PCR. The content of aluminum, cadmium, calcium, chromium, copper, iron, lead, magnesium, manganese, nickel, potassium, sodium, and zinc in young (mean, 32.8 years), middle-aged (mean, 52.3 years), and old (mean, 70.5 years) human lenses was analyzed by inductively coupled plasma-emission spectroscopy.

RESULTS. Lens metallothioneins (Ig, If, Ih, Ie, and IIa) and -crystallin/small heat-shock genes (A-crystallin, B-crystallin, and HSP27) were differentially induced by specific metals in SRA01/04 human lens epithelial cells. Cd²⁺ and Zn²⁺, but not Cu²⁺, induced the metallothioneins, whereas Cd²⁺ and Cu²⁺, but not Zn²⁺, induced B-crystallin and HSP27. A-crystallin was induced by Cu²⁺ only. Similar responses of the metallothionein IIa gene were detected in identically treated primary human lens epithelial cells. Cd²⁺ and Zn²⁺ induced metallothionein IIa to five times higher levels than metallothionein Ig. Of 13 different metals, only iron was altered, exhibiting an 81% decrease in old versus young lenses.

CONCLUSIONS. Induction of metallothioneins and -crystallin/small heat shock proteins by different metals indicates the presence of metal-specific lens regulatory pathways that are likely to be involved in protection against metal-associated stresses.

This article has been cited by other articles:

				M. Posner A Comparative View of Alpha Crystallins: The contribution of comparative studies to understanding function Integr. Comp. Biol., August 1, 2003; 43(4): 481 - 491. [Abstract] [Full Text] [PDF]