Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The synthetic progestins, medroxyprogesterone acetate (MPA) and norethisterone (Net) and its
derivatives (norethisterone enanthate (Net-EN) and norethisterone acetate (Net-A)), are widely used
as contraceptives and in hormone replacement therapy (HRT). Several studies have indicated that
synthetic progestins modulate immune function and increase the risk of sexually transmitted
infections. However, little is known about the molecular mechanism of action of MPA and Net, in
particular their regulation of gene expression in the female genital tract, as compared to
progesterone (P4). In the first part of this thesis, the effect of P4, MPA and Net-A on the expression
of the endogenous chemokine genes, macrophage inflammatory protein (MIP)-1α and MIP-1β, was
investigated in a human vaginal epithelial cell line (Vk2/E6E7). Quantitative realtime PCR (QPCR)
showed that both P4 and MPA upregulated the TNF-α-induced expression of MIP-1α and MIP-1β
mRNA, while Net-A had no effect. Using siRNA technology, it was found that the responses to P4
and MPA on the MIP-1α gene, but not the MIP-1β gene, are mediated via the glucocorticoid
receptor (GR). In the second part of the thesis, it was investigated whether the HIV-1 accessory
protein, viral protein R (Vpr), could modulate the action of ligands on MIP-1α and MIP-1β gene
expression. QPCR showed that Vpr abrogates the effects of P4 and MPA on the TNF-α induced
expression of MIP-1α and MIP-1β. Silencing the GR with siRNA technology showed that the GR
plays a role in the effect of Vpr on the P4 and MPA-induced expression of MIP-1α. Taken together,
these results show that MPA and Net-A display differential effects on chemokine gene expression in
a human vaginal epithelial cell line. Furthermore, this study shows that Vpr modulates the effects of
MPA bound to the GR. Thus, the results of this thesis provide insight into the effect of synthetic
progestins on the immune response in the vagina, and possibly how HIV-infection may alter these
responses. / AFRIKAANSE OPSOMMING: Die sintetiese progestiene medroksieprogesteroon asetaat (MPA) en noretisteroon (Net) en derivate
daarvan (noretisteroon enantaat (Net-EN) en noretisteroon asetaat (Net-A)), word op grootskaal
gebruik as voorbehoedmiddels en in hormoonvervangingsterapie (HVT). Verskeie studies het al
aangedui dat sintetiese progestiene immuunfunksie moduleer en die risiko vir seksuel oordraagbare
infeksies verhoog. Daar is egter min bekend oor die molekulêre meganisme van aksie van MPA en
Net, in die besonder die regulering van geenuitdrukking in die vroulike geslagskanaal in
vergelyking met progesteroon (P4). In die eerste deel van hierdie tesis is die effek van P4, MPA en
Net-A op die uitdrukking van endogene chemokiene gene, makrofaag inflammatoriese proteïen
(MIP)-1α en MIP-1β, in 'n menslike vaginale epiteel sellyn (Vk2/E6E7) bestudeer. Kwantitatiewe
intydse PKR (KPKR) het getoon dat beide P4 en MPA die TNF-α-geïnduseerde uitdrukking van
beide die MIP-1α en MIP-1β mRNA uitdrukking op reguleer, terwyl Net-A geen effek getoon het
nie. Met die gebruik van siRNA-tegnologie is daar bevind dat die effekte van P4 en MPA, bemiddel
word deur die glukokortikoïd-reseptor (GR) op MIP-1α geen uitdrukking, maar nie op MIP-1β nie.
In die tweede deel van die tesis, is ondersoek of die MIV-1-bykomstigheidsproteïen, virale proteïen
R (Vpr), die aksie van die ligande op MIP 1α en MIP-1β geenuitdrukking kan moduleer. KPKR
toon dat Vpr die uitwerking van P4 en MPA op die TNF-α-geïnduseerde uitdrukking van MIP 1α en
MIP-1β kanselleer. Die verwydering van die GR met siRNA-tegnologie toon dat die GR 'n rol in die
uitwerking van Vpr op die P4 en MPA-geïnduseerde uitdrukking van MIP-1α speel. Ter
samevatting: hierdie resultate toon dat MPA en Net-A differensiële uitwerkings vertoon op
chemokiene geenuitdrukking in 'n menslike vaginale epiteel sellyn, en dat Vpr hierdie uitwerkings
moduleer van MPA gobonde aan die GR. Die resultate van hierdie tesis werp dus lig tot die
uitwerking van sintetiese progestiene op die immuunreaksie in die vagina, sowel as hoe MIVinfeksie
hierdie reaksies kan verander.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/20368 |
| Date | 03 1900 |
| Creators | Noeth, Dewald Johan |
| Contributors | Africander, Donita, Hapgood, Janet P., Stellenbosch University. Faculty of Science. Dept. of Biochemistry. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
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