Keratinocyte Growth Factor Inhibits Cross-linked Envelope Formation and Nucleosomal Fragmentation in Cultured Human Keratinocytes

doi:10.1074/jbc.271.11.6245

Keratinocyte Growth Factor Inhibits Cross-linked Envelope Formation and Nucleosomal Fragmentation in Cultured Human Keratinocytes (*)

From the Department of Pathology and Program in Developmental Biology, University of Wisconsin, Madison, Wisconsin 53706

^§To whom correspondence should be addressed. Tel.: 608-262-2884; Fax: 608-265-3301; blallenh{at}facstaff.wisc.edu.

Abstract

Keratinocyte growth factor (KGF) exhibits paracrine action on numerous epithelia, including skin. We have found that cultures of normal human keratinocytes must attain confluence before KGF promotes an increase in cell number relative to untreated controls. In postconfluent cultures, treatment with KGF promoted tight packing of keratinocytes with a small basal cell morphology. Based on these observations, we hypothesized that KGF increased cell number in postconfluent cultures by affecting the ability of normal keratinocytes to undergo terminal differentiation and/or programmed cell death. In support of this hypothesis, keratinocytes treated with KGF produced fewer cross-linked envelopes and exhibited reduced membrane-associated transglutaminase activity relative to cells treated with epidermal growth factor or untreated controls. We also found that nucleosomal fragmentation was reduced in postconfluent cultures of KGF-treated keratinocytes. Furthermore, KGF-treated keratinocytes were more resistant to suspension-induced nucleosomal fragmentation than control or epidermal growth factor-treated cultures. Therefore, it appears that KGF modulates aspects of keratinocyte terminal differentiation which share features with programmed cell death. We propose that stromally-derived KGF may act as a paracrine survival factor in skin and perhaps other renewal tissues.

Footnotes

↵* This work was supported in part by National Institutes of Health Grant AR40284 (to B. L. A. H.), a supplement from the National Institutes of Health Grant R29-AR40285-S1 (to B. L. A. H. and M. D. H.), and an Advanced Opportunity Fellowship from the University of Wisconsin Graduate School (to M. D. H.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

KGF

keratinocyte growth factor

KGFR

keratinocyte growth factor receptor

FGF

fibroblast growth factor

EGF

epidermal growth factor

CE

cross-linked envelope

BSA

bovine serum albumin

TGF-α

transforming growth factor α

PBS

phosphate-buffered saline

TGase

transglutaminase

BrdUrd

5-bromo-2′-deoxyuridine

ELISA

enzyme-linked immunosorbent assay.
↵²K. F. Sachsenmeier and B. L. Allen-Hoffmann, submitted for publication.
- Received October 19, 1995.
- Revision received January 12, 1996.