Correlation of Heparan Sulfate Proteoglycan Structure and Metabolism With the Regulation of Cell Division

Heparan sulfate proteoglycan (HSPG), a ubiquitous cell surface component in animal cells, is a complex, polyanionic macromolecule consisting of a core protein to which are attached several heparan sulfate (HS) chains. Growing and confluent cultures of a rat hepatocyte cell line were labeled with $\sp{35}$SO$\sb4\sp{2-}$ and the HS in the culture medium, the pericellular matrix, the nucleus, the outer nuclear membrane, and the remaining cytoplasmic pool was purified by DEAE-cellulose chromatography. The HS in all pools from the confluent cells exhibited a higher average charge density than the corresponding pools from the growing cells. Analysis of the mixtures of di- and tetrasaccharides formed by cleavage of HS with nitrous acid showed that the structural features of the HS in each pool were different and were altered significantly when growing cells became confluent. The nuclear HS was structurally unique and possessed a high content of sulfated glucuronic acid (GlcUA). The correlation of the levels and structures of HS with cell growth was also observed in primary rat hepatocytes which do not divide in culture, in two rat hepatoma cell lines which exhibited no density-dependent inhibition of growth, and in cytolytic thymic lymphocytes which require interleukin 2 to proliferate. Primary hepatocytes synthesized HS with a structure similar to that made by confluent cultures of the hepatocyte cell line and the nuclear pools contained an elevated sulfated-GlcUA content. The hepatomas produced low levels of HS and the nuclear pools lacked the high content of sulfated GlcUA residues. The lymphocytes exhibited a consistent difference in HS metabolism in the quiescent versus the proliferative state. The addition of HSPG, prepared from confluent monolayers of a rat hepatocyte cell line, to synchronized cultures released from block at the Gl/S boundary arrested the cells in the following Gl phase. Studies of ($\sp{35}$SO$\sb4$) HSPG and $\sp{35}$SO$\sb4\sp{2-}$ uptake and metabolism by synchronized cultures of the hepatocytes revealed a similar pattern of cell cycle-dependent appearance and disappearance of nuclear HS. These results confirm a correlation of HS metabolism with the regulation of cell division.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biochemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Fedarko, Neal Steven

• Chemistry, Biochemistry

Identifier

(UMI)AAI8721629

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70566