integrated into the host chromosome in a manner so 
as to disrupt E2 expression. As a result of integra- 
tion, repression of E6 and E7 is removed, and high 
levels of the transforming proteins are expressed. 
The integration of viral sequences may thus be an 
important step in the progression of HPV-induced 
disease. The amino acids responsible for DNA bind- 
ing and dimerization of the E2 proteins have been 
identified in collaborative studies with Dr. Eliott 
Androphy (Tufts University). The function of E2 
may not be limited to transcription, as studies have 
shov^n it to form a complex with the HPV replica- 
tion protein. El. This E1-E2 complex may play a 
significant role in both the initiation of replication 
and transcriptional regulation. The interplay of viral 
and cellular regulators is a determining factor in 
both the productive stages of HPV infection and in 
HPV-induced cancers. 
Propagation of Human Papillomavirus 
in Tissue Culture 
Dr. Laimins and his colleagues have recently de- 
veloped a method to propagate HPVs in culture. The 
maintenance of viral genomes as episomes is a neces- 
sary prerequisite for virus production, yet when 
viral sequences are transfected into human keratino- 
cytes they quickly integrate into the host chromo- 
some. To overcome this restriction, the laboratory 
has isolated cell lines derived from low-grade cervi- 
cal neoplasias that contain episomal copies of HPV. 
When these ceil lines are allowed to stratify in raft 
cultures in vitro, amplification of viral genomes is 
observed in the highly difl'erentiated suprabasal 
cells in a manner similar to that observed in produc- 
tive infections in vivo. In addition, differentiation- 
specific induction of late transcription is observed 
in raft cultures. Recently Dr. Laimins has been able 
to induce the production in culture of one of the 
oncogenic viral types, HPV 31b, through the addi- 
tion of phorbol esters to the media. This is the first 
propagation of an oncogenic type of HPV in a tissue 
culture system. In the future this system will allow 
for the study of the entire viral life cycle in a tissue 
culture system. A grant from the American Cancer 
Society provided support for the project described 
above. 
Dr. Laimins is also Associate Professor of Molec- 
ular Genetics and Cell Biology and on the Com- 
mittee on Virology at the University of Chicago. 
Articles 
Lechner, M.S., Mack, D.H., Finicle, A.B., Crook, T., 
Vousden, K.H., and Laimins, L.A. 1992. Human 
papillomavirus E6 proteins bind p53 in vivo and 
abrogate p53-mediated repression of transcrip- 
tion. EMBO f 1 1 :3045-3052. 
Mack, D.H., and Laimins, L.A. 1991. A keratino- 
cyte-specific transcription factor, KRF- 1 , interacts 
with AP I to activate expression of human papil- 
lomavirus type 18 in squamous epithelial cells. 
Proc Natl Acad Sci USA 88:9102-9106. 
Meyers, C, Frattini, M.G., Hudson, J.B., and Lai- 
mins, L.A. 1992. Biosynthesis of human papillo- 
mavirus from a continuous cell line upon epithe- 
lial differentiation. Science 257:971-973- 
Prakash, S.S., Grossman, S.R., Pepinsky, R.B., Lai- 
mins, L.A., and Androphy, E.J. 1992. Amino acids 
necessary for DNA contact and dimerization imply 
novel motifs in the papillomavirus E2 ?ran5-acti- 
vator. Genes Dev 6:105-116. 
GENETIC STUDIES IN CARDIOVASCULAR DISEASE 
Jean-Marc Lalouel, M.D., D.Sc, Investigator 
Common cardiovascular disorders such as coro- 
nary artery disease and hypertension exhibit a famil- 
ial tendency. Such broad clinical categories repre- 
sent complex etiological entities, where many 
genes and environmental determinants are likely to 
be involved. Multiplicity and heterogeneity in cau- 
sation stretch the ability of genetic methods to the 
limit. In addition to investigations of familial hyper- 
lipidemias — where the possible contribution of 
two key lipolytic enzymes, lipoprotein lipase and 
hepatic triglyceride lipase, is being examined — re- 
search in Dr. Lalouel 's laboratory also bears on the ge- 
netics of human hypertension. This report summarizes 
progress in the latter area. (This work was supported in 
part by a grant from the National Heart, Lung, and Blood 
Institute, National Institutes of Health.) 
Human hypertension can serve as a genetic para- 
digm of common disease. While linkage analysis be- 
comes increasingly attractive for an ever-broader 
class of familial disorders, hypertension research re- 
quires critical decisions in experimental design, par- 
ticularly with respect to definition of phenotype, 
GENETICS 215 
