Growth Factor-Induced Delayed Early Response Genes

Abstract

Growth factors induce the sequential expression of cellular genes whose products are thought to mediate long-term responses to the growth factors. In mouse 3T3 fibroblastic cells, the first genes to be expressed (immediate-early genes) are activated within minutes after the addition of platelet-derived growth factor, fibroblast growth factor, or serum. By cDNA cloning, we have identified genes that are activated after a delay of a few hours and several hours prior to serum-induced DNA replication. Activation of these delayed early response genes requires new protein synthesis, presumably the synthesis of immediate-early transcription factors described previously. Partial or complete sequencing of 13 different delayed early cDNAs, representing about 40% of the 650 primary cDNA isolates, revealed that 8 were related to known gene sequences and 5 were not. Among the former are cDNAs encoding nonhistone chromosomal proteins [HMGI(Y) and HMGI-C], adenine phosphoribosyltransferase (APRT), a protein related to human macrophage migration inhibitory factor (MIF), a protein of the major intrinsic protein (MIP) family homologous to the integral membrane protein of human erythrocytes, and cyclin CYL1. In 3T3 cells, the delayed early gene response to growth factors appears to be at least as complex as the immediate-early gene response previously described.

Purification, Bioactivity, and Secondary Structure Analysis of Mouse and Human Macrophage Migration Inhibitory Factor (MIF)

“…The muMIF cDNA sequence obtained from six plasmid clones was compared to a previously published human T-cell MIF cDNA (Weiser et al, 1989). Mouse MIF cDNA was found to display a 88.2% sequence homology to this huMIF sequence over a 348-nucleotide open reading frame and to be identical in sequence with recently reported mouse 3T3 fibroblast and mouse embryonic eye lens MIF cDNAs (Lanahan et al, 1992;Wistow et al, 1993;Bemhagen et al, 1993) (EMBL Data Bank, accession number Z23048).…”

A Polypyrimidine/Polypurine Tract within the Hmga2 Minimal Promoter: A Common Feature of Many Growth-Related Genes

“…To ascertain the importance for transcription of the whole ppyr/ppur sequence, we have tested in transfection experiments the luciferase activity of the minimal promoter (HaP) with some deletion mutants. Transient transfections were done with -63mut, -45mut, -38mut, and -24mut in HMGA2-expressing NIH-3T3 mouse fibroblasts (35), and results are reported in Figure 1. Removal of 20 bp from HaP (-63mut) already results in a 2-fold decrease of promoter activity.…”

“…Since it appears from fine mapping results that the promoter region present in a single-stranded form involves nucleotides from -52 to -25, band-shift assays were carried out using as probes either the sense (Cs) or the antisense strand (Cas) of this region to search for potential single strand binding factors that could be involved in Hmga2 gene regulation. When the pyrimidine strand was labeled (Cs) and incubated with nuclear extracts prepared from several HMGA2-expressing cell lines such as NIH-3T3, PC Cl 3 E1A + raf, and QT6 (9,23,35), a specific predominant complex, called "A", was detected for each extract (Figure 5, lanes 2-4). This complex has the same mobility and similar intensity in all nuclear extracts tested and was efficiently competed by a 50-fold molar excess of the selfcold probe (lane 7).…”

Differential in Vivo Modifications of the HMGI(Y) Nonhistone Chromatin Proteins Modulate Nucleosome and DNA Interactions

“…In most normal nondividing cells and tissues, the levels of expression of HMGI(Y) mRNAs and proteins are very low or undetectable but are rapidly induced in response to certain growth stimulatory factors (1,2,(22)(23)(24)(25)(26). In contrast, in neoplastically transformed cells, as well as in embryonic cells that have not yet undergone overt differentiation, the constitutive level of HMGI(Y) gene products is often exceptionally high with increasing concentrations being correlated with increasing degrees of metastatic potential (recently reviewed in ref 27).…”