Lip, a Human Gene Detected by Transfection of DNA From a Human Liposarcoma Encodes a Protein With Homology to Regulators of Small G Proteins

Helen Patterson,Harry Benjamin,Colin S Cooper,Sandra Gill,Philip J Mitchell

doi:10.1080/13577149878145

Abstract

Purpose/Method. Transfection experiments have been used to identify activated oncogenes in a wide variety of tumour types. Here we describe the use of transfection experiments utilizing DNA from a human pleomorphic liposarcoma to identify a novel gene, designated lip which maps to chromosome 19. Results. lip was expressed in all sarcoma cell lines examined and a wide variety of normal tissues. Sequencing of cDNAs prepared from transcripts of the normal lip gene indicates that lip is predicted to encode a 966 amino acid protein with a region of homology to proteins such as vav, dbl, lbc and ect-2 which act as GDP–GTP exchange factors for the RAS superfamily of small GTP-binding proteins, and the N-terminal 830 amino acids are identical to the recently identified gene p115-RhoGEF, an exchange factor for RHOA. In transfectants, lip has undergone a rearrangement which results in C-terminal truncation of the predicted LIP protein. However, we failed to detect this alteration in the primary liposarcoma used in the original transfection experiments, or in other sarcoma specimens examined. Discussion. When considered together, these observations suggest that transforming lip sequences represent an alternatively spliced form of p115-RhoGEF that is activated for transformation by C-terminal truncation during transfection, and is not widely involved in sarcoma development.

Highlights

Transfection of D NA into N IH3T3 mouse ® broblasts has been used to survey a wide variety of hum an tumours for the presence of transform ing oncogenes
In an attempt to identify oncogenes activated in human soft tissue tumours, DNA from 29 sarcomas was examined for the ability to transform NIH3T3 cells.[13]
Complete bidirectional sequencing of clone 11A generated a sequence of 3023 bp including a 39-bp polyA tail. This clone corresponded in size to the 3.0 kb transcript detected by Northern analysis in a variety of human tumour cell lines, the open reading frame present in this cDNA extended to the 59 end of the sequence, raising the possibility that an additional 59 sequence existed

Summary

Introduction

Transfection of D NA into N IH3T3 mouse ® broblasts has been used to survey a wide variety of hum an tumours for the presence of transform ing oncogenes. In addition the N-terminal 830 amino acids are almost completely identical to the recently cloned p115-RhoGEF.[14] Sequencing of cDNA clones isolated from a primary transfectant

Results

Conclusion