The PROGINS polymorphism of the human progesterone receptor diminishes the response to progesterone

Abstract

The human progesterone receptor (PR) is a ligand-dependent transcription factor and two isoforms, (PRA and PRB), can be distinguished. PROGINS, a PR polymorphic variant, affects PRA and PRB and acts as a risk-modulating factor in several gynaecological disorders. Little is known about the functional consequences of this variant. Here, we characterise the properties of PROGINS with respect to transcription, mRNA maturation, protein activity and proliferation. PROGINS is characterised by a 320 bp PV/HS-1 Alu insertion in intron G and two point mutations, V660L in exon 4 and H770H (silent substitution) in exon 5. The Alu element contains a half oestrogen-response element/Sp1-binding site (Alu-ERE/Sp1), which acts as an in-cis intronic enhancer leading to increased transcription of the PROGINS allele in response to 17b-oestradiol. Moreover, Alu insertions in the human genome are frequently methylated. Our data indicate that the PROGINS-Alu does not affect gene transcription due to DNA methylation. However, the Alu element reduced the stability of the PROGINS transcript compared with the CP allele and does not generate splice variants. The amino acid substitution (V600L) in exon 4 leads to differences in PR phosphorylation and degradation in the two PR variants upon ligand binding, most likely as a result of differences in the three-dimensional structures of the two PR variants. As a consequence, the PR-L660 (PROGINS) variant (1) displays decreased transactivation activity in a luciferase reporter system and (2) is less efficient in opposing cell proliferation in hamster ovarian cells expressing human PRA, when compared with the PR-V660 (most common variant). Taken together, our results indicate that the PROGINS variant of PR is less responsive to progestin compared with the most common PR because of (i) reduced amounts of gene transcript and (ii) decreased protein activity.

Progesterone receptor variation and risk of ovarian cancer is limited to the invasive endometrioid subtype: results from the ovarian cancer association consortium pooled analysis

“…However, this finding was amongst all cell types (Akahira et al, 2000). There is also a suggestion that the PROGINS allele as defined by the V660L exon five variant (as examined in the present study) decreases overall response to progesterone which would be consistent with an increased risk of disease associated with this variant (Romano et al, 2007).…”

Association of progesterone receptor gene polymorphism with male infertility and clinical outcome of ICSI

“…This polymorphic variant is also functionally relevant as presence of PROGINS in the PR affects the stability of its mRNA and the resulting protein has reduced response to progesterone [33]. To test if the PROGINS insertion may be a cause of reduced PR expression and or its activity in the infertile men, we screened for its presence in the DNA of fertile and infertile individuals.…”

“…Recent clinical and experimental evidences have indeed suggested that epigenetic defects in the sperm DNA is associated with recurrent spontaneous abortions [4,31]. Since the PR mRNA is expressed in the mature spermatozoa [37,38] and the PROGINS polymorphism is associated with defective PR transcription [11,33], we tested if the PROGINS insertion in the paternal genome has any effect on fertilization, embryo quality and pregnancy rates. However, no significant differences were noted when these parameters were compared in the group, where the male partner had PROGINS allele vs the wild type allele.…”

“…Characterized by a 320 bp PV/HS-1 Alu insertion in intron G and two point mutations, V660L in exon 4 and H770H (silent substitution) in exon 5; the Alu element contains a half oestrogenresponse element/Sp1-binding site (Alu-ERE/Sp1), which acts as an in-cis intronic enhancer leading to increased transcription of the PROGINS allele in response to 17beta-oestradiol. The Alu element reportedly reduces the stability of the PROGINS transcript compared with the wild allele; the amino acid substitution V600L leads to differences in PR phosphorylation and degradation upon ligand binding, most likely as a result of differences in the three-dimensional structures of the variant [33]. As a consequence, the PROGINS variant displays decreased transactivation activity, the resulting protein has poor bioactivity and affects cell cycle in cultured endometrial cells [11,33].…”

“…The Alu element reportedly reduces the stability of the PROGINS transcript compared with the wild allele; the amino acid substitution V600L leads to differences in PR phosphorylation and degradation upon ligand binding, most likely as a result of differences in the three-dimensional structures of the variant [33]. As a consequence, the PROGINS variant displays decreased transactivation activity, the resulting protein has poor bioactivity and affects cell cycle in cultured endometrial cells [11,33]. Intriguingly, studies have demonstrated that the presence of this polymorphism increases the risk of women towards gynecologic disorders including cancers [30,32,34,39].…”