Identification and Characterization of a Gene Encoding a Gut-enriched Krüppel-like Factor Expressed during Growth Arrest

doi:10.1074/jbc.271.33.20009

Identification and Characterization of a Gene Encoding a Gut-enriched Krüppel-like Factor Expressed during Growth Arrest*

From the Departments of ^‡ Medicine and
^∥ Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 and the
^¶ Center for Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center, San Antonio, Texas 78250

**To whom correspondence should be addressed:
Dept. of Medicine, Ross 918, The Johns Hopkins University School of Medicine, 720 Rutland Ave., Baltimore, MD 21205.
Tel.: 410-955-9691; Fax: 410-955-9677; E-mail: vyang{at}welchlink.welch.jhu.edu.

Abstract

A cDNA clone, named gut-enriched Krüppel-like factor (GKLF), was isolated from an NIH 3T3 library using a probe encoding the zinc finger region of the immediate-early transcription factor zif/268. The deduced GKLF amino acid sequence contains three tandem zinc fingers that are related to members of the Krüppel family of transcription factors. By indirect immunofluorescence, GKLF is localized to the cell nucleus. In cultured fibroblasts, GKLF mRNA is found in high levels in growth-arrested cells and is nearly undetectable in cells that are in the exponential phase of proliferation. The growth-arresting nature of GKLF is demonstrated by an inhibition of DNA synthesis in cells transfected with a GKLF-expressing plasmid construct. In the mouse, GKLF mRNA is present in select tissues and is most abundant in the colon, followed by the testis, lung, and small intestine. In situ hybridization experiments indicate that GKLF mRNA is enriched in epithelial cells located in the middle to upper crypt region of the colonic mucosa. Taken together, these results suggest that GKLF is potentially a negative regulator of cell growth in tissues such as the gut mucosa, where cell proliferation is intimately coupled to growth arrest and differentiation.

Footnotes

↵^§ Supported by a National Research Service Award from the National Institutes of Health.
↵* This work was supported in part by grants from the National Institutes of Health (to V. W. Y. and R. J. C.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

EKLF

erythroid Krüppel-like factor

GKLF

gut-enriched Krüppel-like factor

LKLF

lung Krüppel-like factor

bp

base pair(s)

ORF

open reading frame

PBS

phosphate-buffered saline

BrdUrd

bromodeoxyuridine

DMEM

Dulbecco's modified Eagle's medium

FCS

fetal calf serum

BTEB2

basic transcription element-binding protein 2.
↵²K. Okubo, unpublished data.
- Received December 29, 1995.
- Revision received April 16, 1996.