Transportation Course of Macromolecules to the Nucleus from the Extracellular Environment: Steroid Hormones’ Cellular Entry Mode Revisited

Toshikazu Nishimura

doi:10.11648/j.cb.20180601.12

Abstract

Polyomavirus virions such as simian virus 40 (SV40), antinuclear antibodies such as immunoglobulin G (IgG) and steroid hormones all enter the nucleus from the extracellular environment. Testosterone-bovine serum albumin conjugate labeled with 2 nm colloidal gold (testosterone-BSA-gold) is taken up by endocytosis into target cells, and enter the nucleus through a similar route as SV40 nuclear migration. Upon injection into the vascular system of rats, IgG coupled with hydrocortisone also enters the hormone-target cell nuclei with intact antigenicity. These results suggest that steroid hormones could act as transporters to deliver exogenous macromolecules, e.g. drugs, into their target cell nuclei <i>in vivo</i>, although further studies are required on whether steroid hormones coupled with proteins exert genomic actions in the nucleus, etc. Finally, testosterone-BSA-gold seems to be isolated from the cytosol in the processes of nuclear entry. Together, these findings challenge the popular belief that steroid hormones mostly enter the cell in unbound form via uncontrolled passive diffusion.

Highlights

Various large molecules destined for cell nucleus arrive from the extracellular environment
Native immunoglobulin G (IgG) does not pass freely the cell- or nuclear membrane; IgG introduced to the cytoplasm did not enter the nucleus [1, 2]
Environment: Steroid Hormones’ Cellular Entry Mode Revisited nucleoplasmic side of the inner nuclear membrane [9, 10]. These results suggest that simian virus 40 (SV40)-containing vesicle membrane fuses to a single-bilayer diaphragm in the nuclear envelope in order to transport virus particles into the nucleoplasm, and that the exogenous macromolecules used here as cell membrane markers were transported into the nucleus in this manner (Figure 1b) [9]

Summary

Introduction

Various large molecules destined for cell nucleus arrive from the extracellular environment. Native IgG does not pass freely the cell- or nuclear membrane; IgG introduced to the cytoplasm did not enter the nucleus [1, 2] Polyomavirus virions such as simian virus 40 (SV40) comprise proteins and DNA, and are able to enter the nucleus from the extracellular environment [3]. Environment: Steroid Hormones’ Cellular Entry Mode Revisited nucleoplasmic side of the inner nuclear membrane [9, 10] These results suggest that SV40-containing vesicle membrane fuses to a single-bilayer diaphragm in the nuclear envelope in order to transport virus particles into the nucleoplasm, and that the exogenous macromolecules used here as cell membrane markers were transported into the nucleus in this manner (Figure 1b) [9]

Diaphragms in Nuclear Envelope

Conclusion