PGRMC1 localization and putative function in the nucleolus of bovine granulosa cells and oocytes

Review: The putative role of Progesterone Receptor membrane Component 1 in bovine oocyte development and competence

Acquisition of developmental competence is a complex process in which many cell types cooperate to support oocyte maturation, fertilisation, and preimplantation embryonic development. In recent years, compelling evidence has shown that Progesterone Receptor Membra Component 1 (PGRMC1) is expressed in many cell types of the mammalian reproductive system where it exerts diverse functions. In the ovary, PGRMC1 affects follicular growth by controlling cell viability and proliferation of granulosa cells. PGRMC1 has also a direct role in promoting a proper completion of bovine oocyte maturation, as altering its function leads to defective chromosome segregation and polar body extrusion. Strikingly, the mechanism by which PGRMC1 controls mitotic and meiotic cell division seems to be conserved, involving an association with the spindle apparatus and the chromosomal passenger complex through Aurora kinase B. Conclusive data on a possible role of PGRMC1 in the preimplantation embryo are lacking and further research is needed to test whether the mechanisms that are set in place in mitotic cells also govern blastomere cleavage and subsequent differentiation. Finally, PGRMC1 is also expressed in oviductal cells and, as such, it might also impact fertilisation and early embryonic development, although this issue is completely unexplored. However, the study of PGRMC1 function in the mammalian reproductive system remains a complex matter, due to its pleiotropic function.

Insights on the Role of PGRMC1 in Mitotic and Meiotic Cell Division

During mitosis, chromosome missegregation and cytokinesis defects have been recognized as hallmarks of cancer cells. Cytoskeletal elements composing the spindle and the contractile ring and their associated proteins play crucial roles in the faithful progression of mitotic cell division. The hypothesis that PGRMC1, most likely as a part of a yet-to-be-defined complex, is involved in the regulation of spindle function and, more broadly, the cytoskeletal machinery driving cell division is particularly appealing. Nevertheless, more than ten years after the preliminary observation that PGRMC1 changes its localization dynamically during meiotic and mitotic cell division, this field of research has remained a niche and needs to be fully explored. To encourage research in this fascinating field, in this review, we will recap the current knowledge on PGRMC1 function during mitotic and meiotic cell division, critically highlighting the strengths and limitations of the experimental approaches used so far. We will focus on known interacting partners as well as new putative associated proteins that have recently arisen in the literature and that might support current as well as new hypotheses of a role for PGRMC1 in specific spindle subcompartments, such as the centrosome, kinetochores, and the midzone/midbody.

Pleiotropic Actions of PGRMC Proteins in Cancer

Progesterone receptor membrane component (PGRMC) proteins play important roles in tumor growth, progression, and chemoresistance, of which PGRMC1 is the best characterized. The ancestral member predates the evolution of metazoans, so it is perhaps not surprising that many of the purported actions of PGRMC proteins are rooted in fundamental metabolic processes such as proliferation, apoptosis, and DNA damage responses. Despite mediating some of the actions of progesterone (P4) and being fundamentally required for female fertility, PGRMC1 and PGRMC2 are broadly expressed in most tissues. As such, these proteins likely have both progesterone-dependent and progesterone-independent functions. It has been proposed that PGRMC1 acquired the ability to mediate P4 actions over evolutionary time through acquisition of its cytochrome b5-like heme/sterol-binding domain. Diverse reproductive and nonreproductive diseases associate with altered PGRMC1 expression, epigenetic regulation, or gene silencing mechanisms, some of which include polycystic ovarian disease, premature ovarian insufficiency, endometriosis, Alzheimer disease, and cancer. Although many studies have been completed using transformed cell lines in culture or in xenograft tumor approaches, recently developed transgenic model organisms are offering new insights in the physiological actions of PGRMC proteins, as well as pathophysiological and oncogenic consequences when PGRMC expression is altered. The purpose of this mini-review is to provide an overview of PGRMC proteins in cancer and to offer discussion of where this field must go to solidify PGRMC proteins as central contributors to the oncogenic process.

Bovine models for human ovarian diseases

During early embryonic development, late fetal growth, puberty, adult reproductive years, and advanced aging, bovine and human ovaries closely share molecular pathways and hormonal signaling mechanisms. Other similarities between these species include the size of ovaries, length of gestation, ovarian follicular and luteal dynamics, and pathophysiology of ovarian diseases. As an economically important agriculture species, cattle are a foundational species in fertility research with decades of groundwork using physiologic, genetic, and therapeutic experimental techniques. Many technologies used in modern reproductive medicine, such as ovulation induction using hormonal therapy, were first used in cows before human trials. Human ovarian diseases with naturally occurring bovine correlates include premature ovary insufficiency (POI), polycystic ovarian syndrome (PCOS), and sex-cord stromal tumors (SCSTs). This article presents an overview of bovine ovary research related to causes of infertility, ovarian diseases, diagnostics, and therapeutics, emphasizing where the bovine model can offer advantages over other lab animals for translational applications.

PGRMC1 Exerts Its Function of Anti-Influenza Virus in the Central Nervous System

The influenza A virus (IAV) infection is usually restricted to the respiratory tract and only rarely enters the central nervous system (CNS) and causes neurological symptoms. However, the roles of host factors involved in IAV infection in the CNS remain largely undetermined. Therefore, we aimed to characterize the host responses to IAV infection in the brain. We isolated a strain of IAV H5N6, which is neurotoxic and highly pathogenic to mice. High-throughput RNA sequencing (RNA-seq) revealed 240 differentially expressed genes in IAV-infected brains. Among the significantly downregulated genes, we focused on the gene encoding progesterone receptor membrane component-1 (PGRMC1) and observed that IAV H5N6 infection clearly inhibited PGRMC1 in both neuroblastoma and glioma cells. Furthermore, treatment with AG205, a PGRMC1-specific inhibitor, or PGRMC1 knockout promoted H5N6 multiplication in vitro, while overexpression of PGRMC1 resulted in opposite effects. Furthermore, AG205 treatment or PGRMC1 knockout significantly inhibited the retinoic acid-inducible gene I (RIG-I)-mediated interferon beta (IFN-β) signaling pathway and reduced the levels of several antiviral proteins (Mx1 and ISG15). In addition, PGRMC1-mediated regulation of IFN signaling relied on inhibition of the expression and ubiquitination of RIG-I. The loss of PGRMC1 leads to an increased susceptibility of mice (brain and lung) to influenza A virus infection. Conclusively, our results show for the first time that IAV H5N6 downregulates PGRMC1 expression to contribute to virus proliferation by inhibiting RIG-I-mediated IFN-β production in the brain. These findings may offer new insights regarding the interplay between IAV and host factors that may impact IAV pathogenicity in the brain.

IMPORTANCE Central nervous system (CNS) disease is one of the most common extra-respiratory tract complications of influenza A virus (IAV) infections. However, there is still little knowledge about IAV regulating host responses in brain. In this study, we identified progesterone receptor membrane component-1 (PGRMC1) as a novel host factor involved in the replication and propagation of IAV H5N6 in the host brain. We also observed that PGRMC1 antagonism was required for viral evasion from the host immune response during IAV infection via inhibition of the retinoic acid-inducible gene I (RIG-I)-mediated interferon beta (IFN-β) signaling pathway and downstream antiviral gene expression. This study revealed a newly identified regulatory mechanism used by IAV H5N6 to ensure its life cycle in the CNS.

Progesterone Modulates Mitochondrial Functions in Human Glioblastoma Cells

A substantial literature supports the notion that cancer is a metabolic disease. Mitochondria are sexually dimorphic, and progesterone (P4) plays a key regulatory role in mitochondrial functions. We investigated the effect of P4 on mitochondrial functions in three human glioblastoma multiforme (GBM) cell lines. In dose-response and time-response studies, GBM cells were exposed to different concentrations of P4 followed by mitochondrial stress-testing with a Seahorse analyzer. Data were analyzed for oxygen consumption rate (OCR), extracellular acidification rate (ECAR), and spare respiratory capacity (SRC) to determine the effects of P4 exposure on mitochondrial respiration and rate of glycolysis. We also examined the effect of P4 on mitochondrial superoxide radical generation by confocal microscopy. As early as 1h post-P4 exposure, we found a substantial dose-dependent inhibitory effect of P4 on OCR, ECAR, and SRC in all GBM cell lines. P4 treatment altered the levels of basal respiration, maximum respiration, nonmitochondrial oxygen consumption, ATP production, and proton leak. P4 given at 80-μM concentration showed the maximum inhibitory effect compared to controls. Live imaging data showed an 11-22% increase in superoxide radical generation in all three GBM cell lines following 6h exposure to a high concentration of P4. Our data show that high-dose P4 exerts an inhibitory effect on both mitochondrial respiration and glycolysis in GBM cells. These effects would lead to decreased tumor size and rate of growth, representing a potential treatment to control the spread of GBM.

The nucleolus-like and precursor bodies of mammalian oocytes and embryos and their possible role in post-fertilization centromere remodelling

In nearly all somatic cells, the ribosome biosynthesis is a key activity. The same is true also for mammalian oocytes and early embryos. This activity is intimately linked to the most prominent nuclear organelles - the nucleoli. Interestingly, during a short period around fertilization, the nucleoli in oocytes and embryos transform into ribosome-biosynthesis-inactive structures termed nucleolus-like or nucleolus precursor bodies (NPBs). For decades, researchers considered these structures to be passive repositories of nucleolar proteins used by the developing embryo to rebuild fully functional, ribosome-synthesis competent nucleoli when required. Recent evidence, however, indicates that while these structures are unquestionably essential for development, the material is largely dispensable for the formation of active embryonic nucleoli. In this mini-review, we will describe some unique features of oocytes and embryos with respect to ribosome biogenesis and the changes in the structure of oocyte and embryonic nucleoli that reflect this. We will also describe some of the different approaches that can be used to study nucleoli and NPBs in embryos and discuss the different results that might be expected. Finally, we ask whether the main function of nucleolar precursor bodies might lie in the genome organization and remodelling and what the involved components might be.

PGRMC Proteins Are Coming of Age: A Special Issue on the Role of PGRMC1 and PGRMC2 in Metabolism and Cancer Biology

This is a preface by the guest editors of the special issue of Cancers featuring the biology of progesterone (P4) receptor membrane component (PGRMC) proteins as it relates to metabolism and cancer [...].

Corpora lutea affect in vitro maturation of bovine cumulus-oocyte complexes and embryonic development after fertilization with sex-sorted or conventional semen

Influence of both the presence of a corpus luteum on the ovary and semen sex-sorting on development following in vitro fertilization is not yet conclusive. To determine the effect of these factors, 376 bovine oocytes were processed in vitro according to luteal presence on the ovary (CL+ and CL-) and type of semen used (sexed or conventional). Maturation rate was higher (P < 0.01) in CL- (136/138; 98.6%) than in CL+ (217/238; 91.2%). Cleavage rate was lower (P < 0.01) in CL+ with sexed semen (60/172; 34.9%) than in CL- with sexed semen (42/71; 59.1%), CL+ with conventional semen (47/66; 71.2%), and CL- with conventional semen (54/67; 85.1%). Compaction was similar (P = 0.69) in CL- (49/99; 49.4%) and CL+ (50/107; 46.7%). Blastulation rate was higher (P < 0.01) in CL- (26/99, 26.2%) than in CL+ (13/107; 12.1%) group. Expansion rate was higher (P = 0.01) in CL- (22/99; 22%) than in CL+ (11/107; 10.2%) group. Compaction rates were similar (P = 0.78) in sex-sorted (50/102; 49.0%) or conventional semen (49/104; 47.1%) groups. Blastulation was also similar (P = 0.91) with sex-sorted semen (19/102; 18.6%) and conventional semen (20/104; 19.2%). The rate of expanded blastocysts was similar (P = 0.89) in sex-sorted (16/102; 15.6%) and conventional (17/104; 16.3%) semen groups. In conclusion, the presence of CL can compromise maturation of the oocytes and their development, as a higher proportion of cleavage-stage embryos can be obtained with non-sexed semen with oocytes from ovaries without a CL.

PGRMC1 effects on metabolism, genomic mutation and CpG methylation imply crucial roles in animal biology and disease

Background

Progesterone receptor membrane component 1 (PGRMC1) is often elevated in cancers, and exists in alternative states of phosphorylation. A motif centered on PGRMC1 Y180 was evolutionarily acquired concurrently with the embryological gastrulation organizer that orchestrates vertebrate tissue differentiation.

Results

Here, we show that mutagenic manipulation of PGRMC1 phosphorylation alters cell metabolism, genomic stability, and CpG methylation. Each of several mutants elicited distinct patterns of genomic CpG methylation. Mutation of S57A/Y180/S181A led to increased net hypermethylation, reminiscent of embryonic stem cells. Pathways enrichment analysis suggested modulation of processes related to animal cell differentiation status and tissue identity, as well as cell cycle control and ATM/ATR DNA damage repair regulation. We detected different genomic mutation rates in culture.

Conclusions

A companion manuscript shows that these cell states dramatically affect protein abundances, cell and mitochondrial morphology, and glycolytic metabolism. We propose that PGRMC1 phosphorylation status modulates cellular plasticity mechanisms relevant to early embryological tissue differentiation.

Early eukaryotic origins and metazoan elaboration of MAPR family proteins

The membrane-associated progesterone receptor (MAPR) family consists of heme-binding proteins containing a cytochrome b₅ (cytb₅) domain characterized by the presence of a MAPR-specific interhelical insert region (MIHIR) between helices 3 and 4 of the canonical cytb5-domain fold. Animals possess three MAPR genes (PGRMC-like, Neuferricin and Neudesin). Here we show that all three animal MAPR genes were already present in the common ancestor of the opisthokonts (comprising animals and fungi as well as related single-celled taxa). All three MAPR genes acquired extensions C-terminal to the cytb₅ domain, either before or with the evolution of animals. The archetypical MAPR protein, progesterone receptor membrane component 1 (PGRMC1), contains phosphorylated tyrosines Y139 and Y180. The combination of Y139/Y180 appeared in the common ancestor of cnidarians and bilaterians, along with an early embryological organizer and synapsed neurons, and is strongly conserved in all bilaterian animals. A predicted protein interaction motif in the PGRMC1 MIHIR is potentially regulated by Y139 phosphorylation. A multilayered model of animal MAPR function acquisition includes some pre-metazoan functions (e.g., heme binding and cytochrome P450 interactions) and some acquired animal-specific functions that involve regulation of strongly conserved protein interaction motifs acquired by animals (Metazoa). This study provides a conceptual framework for future studies, against which especially PGRMC1's multiple functions can perhaps be stratified and functionally dissected.

PGRMC1 phosphorylation affects cell shape, motility, glycolysis, mitochondrial form and function, and tumor growth

BACKGROUND

Progesterone Receptor Membrane Component 1 (PGRMC1) is expressed in many cancer cells, where it is associated with detrimental patient outcomes. It contains phosphorylated tyrosines which evolutionarily preceded deuterostome gastrulation and tissue differentiation mechanisms.

RESULTS

We demonstrate that manipulating PGRMC1 phosphorylation status in MIA PaCa-2 (MP) cells imposes broad pleiotropic effects. Relative to parental cells over-expressing hemagglutinin-tagged wild-type (WT) PGRMC1-HA, cells expressing a PGRMC1-HA-S57A/S181A double mutant (DM) exhibited reduced levels of proteins involved in energy metabolism and mitochondrial function, and altered glucose metabolism suggesting modulation of the Warburg effect. This was associated with increased PI3K/AKT activity, altered cell shape, actin cytoskeleton, motility, and mitochondrial properties. An S57A/Y180F/S181A triple mutant (TM) indicated the involvement of Y180 in PI3K/AKT activation. Mutation of Y180F strongly attenuated subcutaneous xenograft tumor growth in NOD-SCID gamma mice. Elsewhere we demonstrate altered metabolism, mutation incidence, and epigenetic status in these cells.

CONCLUSIONS

Altogether, these results indicate that mutational manipulation of PGRMC1 phosphorylation status exerts broad pleiotropic effects relevant to cancer and other cell biology.

Progesterone Increases Mitochondria Membrane Potential in Non-human Primate Oocytes and Embryos

Mitochondrial activity is critical and correlates with embryo development. The identification of a novel human mitochondrial progesterone receptor (PR-M) that increases cellular respiration brings into question a role for progesterone in oocyte and preimplantation embryo development. Oocytes and embryos were generated from three Rhesus non-human primates (Macaca mulatta) undergoing in vitro fertilization. Immunohistochemical (IHC) staining for the progesterone receptor and mitochondria, RT-PCR with product sequencing for a mitochondrial progesterone receptor, and mitochondrial membrane determination with JC-1 staining were performed. IHC staining with selective antibodies to the progesterone receptor showed non-nuclear staining. Staining was absent in mouse control embryos. RT-PCR with product sequencing demonstrated PR-M transcript in Rhesus oocytes and embryos, which was absent in mouse embryos. Treatment of Rhesus oocytes and embryos with progesterone showed increased mitochondrial membrane potential, which was absent in mouse embryos. Our results support that progesterone increases mitochondrial membrane potential in oocytes and developing embryos. This is likely an in vivo mechanism to support preimplantation embryo development, and brings up the possibility of in vitro manipulation of culture media for optimization of growth.

Progesterone induced Warburg effect in HEK293 cells is associated with post-translational modifications and proteasomal degradation of progesterone receptor membrane component 1

Progesterone (P4) is a major steroid hormone that has important effects on metabolism. The progesterone receptor membrane component 1 (PGRMC1) is a non-canonical P4 binding protein. The biological functions affected by PGRMC1 include cholesterol/steroid biosynthesis and metabolism, iron homeostasis and heme trafficking, autophagy, regulation of cell cycle and proliferation, cell migration and invasion. PGRMC1 has been an attractive target for therapeutic intervention in cancer and neurodegenerative disorders due to its biological role in promoting cell survival. P4 has been used in a number of clinical applications and is considered neuroprotective. The involvement of PGRMC1 in P4-mediated regulation of cellular glucose metabolism is not well studied. PGRMC1 is a 21 kDa protein but complex post-translational modifications (PTMs) lead to the existence of several high molecular mass proteins whose molecular function, intracellular distribution, and physiological relevancies are not fully known. Therefore, in this study, P4-PGRMC1-mediated cellular glucose metabolism and PTMs of PGRMC1 were studied using wild-type and CRISPR/Cas9 mediated PGRMC1 knockout (KO) human embryonic kidney-derived (HEK293) cell lines. A 70 kDa (p70) and 100 kDa (p100) PGRMC1 proteins were identified that are predominantly associated with endoplasmic reticulum/mitochondria and nuclear fractions in the cells, respectively. Phosphorylation, acetylation, ubiquitination, and sumoylation of native PGRMC1 under serum starvation were identified which provided an explanation for the higher molecular masses. This study indicates that P4-PGRMC1 signaling caused a rapid increase in glycolysis in the presence of oxygen (aerobic glycolysis) and a corresponding decrease in cellular respiration, known as the Warburg effect. Further, it was demonstrated that the P4-induced increase in glycolysis is associated with rapid proteasomal degradation of the p70 and reduction of the nuclear p100 protein level. P4 treatment also caused significant alteration in the dynamics of PGRMC1 PTMs and its association with potential interacting proteins. Overall, this study provides a hitherto unknown aspect of P4-PGRMC1 mediated signaling that changes basic cellular metabolism in HEK293 cells.

A dileucine motif in the COOH-terminal domain of NKCC1 targets the cotransporter to the plasma membrane

Na⁺-K⁺-2Cl^- cotransporter-1 (NKCC1) mediates the electroneutral transport of Na⁺, K⁺, and Cl^- and is normally localized to the basolateral membrane of polarized epithelial cells. We recently reported the first known solute carrier family 12 member 2 ( SLC12A2) mutation (we call NKCC1-DFX) that causes epithelial dysfunction in an undiagnosed disease program case. The heterozygous mutation leads to truncation of the COOH-terminal tail of the cotransporter, resulting in both mutant and wild-type cotransporters being mistrafficked to the apical membrane of polarized epithelial cells. Here we demonstrate by using consecutive truncations and site-directed mutagenesis of the COOH-terminal domain of NKCC1 that truncation of NKCC1 COOH domain uncouples the cotransporter from the lateral membrane. We identify a dileucine motif that, when mutated, leads to cotransporter accumulation in the cytoplasm and mistrafficking to the apical/subapical region of epithelial cells, thereby recapitulating the phenotype observed with the patient mutation. We show that truncation deletion and LL substitution mutants are trafficked out of the endoplasmic reticulum and trans-Golgi network but accumulate in early and late endosomes where they are degraded.

Progestins Inhibit Tumor Necrosis Factor α-Induced Matrix Metalloproteinase 9 Activity via the Glucocorticoid Receptor in Primary Amnion Epithelial Cells

Progestins have been recommended for preterm birth prevention in high-risk women; however, their mechanism of action still remains an area of debate. Medroxyprogesterone acetate (MPA) has previously been shown to significantly inhibit tumor necrosis factor α (TNFα)-induced matrix metalloproteinase 9 (MMP9) messenger RNA (mRNA) expression and activity in primary amnion epithelial cells, a process that may lead to preterm premature rupture of membranes. A mechanism that explains MPA's inhibition of TNFα-induced MMP9 mRNA expression and activity in primary amnion epithelial cells is unclear since these cells lack the classic nuclear progesterone receptor but express a membrane-associated progesterone receptor-progesterone receptor membrane component 1 (PGRMC1) along with the glucocorticoid receptor (GR). Primary amnion epithelial cells harvested from healthy term pregnant women at cesarean section were treated with PGRMC1 (to knockdown PGRMC1 expression), GR (to knockdown GR expression), or control small interfering RNA (siRNA; 10 nm) for 72 hours, pretreated with ethanol or MPA (10^-6 M) for 6 hours, and then stimulated with or without TNFα 10 ng/mL for 24 hours. Real-time quantitative polymerase chain reaction and gelatin zymography were used to quantify MMP9 mRNA expression and activity, respectively. Experimental groups were compared using 1-way analysis of variance. Both TNFα-induced MMP9 mRNA expression and activity were significantly inhibited by pretreatment with MPA; however, only the inhibition of TNFα-induced MMP9 activity was partially reversed with PGRMC1 siRNA. However, GR siRNA reversed both the inhibition of TNFα-induced MMP9 mRNA expression and activity by MPA. This study demonstrates that MPA mediates its anti-inflammatory effects primarily through GR and partially through PGRMC1 in primary amnion epithelial cells.