Expression and Regulation of Lipocalin-Type Prostaglandin D Synthase in Rat Testis and Epididymis1

Distinct actions of testicular endocrine and lumicrine signaling on the proximal epididymal transcriptome

The epididymal function and gene expression in mammals are under the control of the testis. Sex steroids are secreted from the testis and act on the epididymis in an endocrine manner. There is another, non-sex steroidal secreted signaling, named lumicrine signaling, in which testis-derived secreted proteins go through the male reproductive tract and act on the epididymis. The effects of such multiple regulations on the epididymis by the testis have been investigated for many genes. The recent development of high-throughput next-generation sequencing now enables us a further comparative survey of endocrine and lumicrine action-dependent gene expression. In the present study, testis-derived endocrine and lumicrine actions on epididymal gene expression were comparatively investigated by RNA-seq transcriptomic analyses. This investigation utilized experimental animal models in which testis-derived endocrine and/or lumicrine actions were interfered with, such as unilateral or bilateral orchidectomy. By bilateral orchidectomy, which interferes with both endocrine and lumicrine actions, 431 genes were downregulated. By unilateral orchidectomy, which also interferes with endocrine and lumicrine actions by the unilateral testis, but the endocrine action was compensated by the contralateral testis, 283 genes were downregulated. The content of such genes downregulated by unilateral orchidectomy was like those of lumicrine action-interfered efferent duct-ligation, W/Wv, and Nell2-/- mice. When genes affected by unilateral and bilateral orchidectomy were compared, 154 genes were commonly downregulated, whereas 217 genes were specifically downregulated only by bilateral orchidectomy, indicating the distinction between endocrine and lumicrine actions on the proximal epididymal transcriptome. Comparative transcriptome analyses also showed that the expressions of genes emerging since Amniota were notably impacted by bilateral orchidectomy, unilateral orchidectomy, and lumicrine action-interfering treatments; the degree of influence from these treatments varied based on the evolutionary stage beyond Amniota. These findings unveil an evolutional transition of regulated gene expression in the proximal epididymis by two different testis-derived signaling mechanisms.

Busulfan administration replicated the characteristics of the epididymal initial segment observed in mice lacking testis-epididymis lumicrine signaling

The physiological functions of the mammalian epididymis are typically regulated by the testes. In addition to sex steroids secreted by testicular Leydig cells, which act on the epididymis in an endocrine manner, there is a non-sex-steroidal signaling pathway known as the lumicrine pathway. This lumicrine signaling pathway involves ligand proteins secreted from germ cells within the testicular seminiferous tubules traversing the male reproductive tract, which induce epithelial differentiation in the epididymis. These findings prompted an inquiry into whether treatments influencing testis physiology can disrupt epididymal function by interfering with testis-epididymis communication. Busulfan, an alkylating agent commonly used to deplete testicular germ cells in reproductive biology, has not been sufficiently explored because of its effects on the epididymis. This study investigated the effects of busulfan administration on the proximal epididymis using histological and transcriptomic analyses. Notably, busulfan, as opposed to the vehicle dimethyl sulfoxide (DMSO), altered the morphology of the initial segment of the epididymis, leading to a reduction in the cell height of the luminal epithelium. RNA sequencing identified 185 significantly downregulated genes in the proximal epididymis of busulfan-administered mice compared to DMSO-administered mice. Comparative transcriptome analyses revealed similarities between the epididymal transcriptome of busulfan-administered mice and lumicrine-deficient mice, such as efferent-duct-ligated W/Wv and Nell2-/- mice. However, this differed from that of bilaterally orchidectomized mice, in which both the endocrine and lumicrine signaling pathways were simultaneously ablated. Collectively, these results suggested that the harmful effects of busulfan on the proximal epididymis are secondary consequences of the ablation of testis-epididymis lumicrine signaling.

Association between Family History and Male Androgenetic Alopecia with Female Pattern Hair Loss

BACKGROUND

Male androgenetic alopecia (MAGA) is often accompanied by female pattern hair loss (FPHL). However, the risk factors related to MAGA with FPHL are unclear.

OBJECTIVE

To investigate demographic and laboratory factors related to MAGA with FPHL.

METHODS

This retrospective case-control study was performed in a single tertiary care center for MAGA with FPHL between March 2012 and September 2021. Eligible patients were males >12 years old diagnosed with androgenetic alopecia by a dermatologist. The patients were subdivided into MAGA with FPHL and MAGA without FPHL groups. Comorbidities as well as demographic, laboratory, and disease-specific variables were compared between the two groups. Data analysis was conducted between October 2021 and February 2022. The independent samples t-test, Mann-Whitney U test, and chi-squared test were used to assess the factors that contributed to MAGA with FPHL.

RESULTS

Of 469 patients with MAGA, 309 (65.9%) had FPHL, which was a much higher rate than previously reported. Among the variables, only matrilineal (odds ratio, 1.605; 95% confidence interval, 1.014~2.541) and maternal history (odds ratio, 4.705; confidence interval, 1.632~13.559) of androgenetic alopecia were significantly associated with MAGA with FPHL. In the MAGA with FPHL group, a significant positive correlation was noted between body mass index and the type F score (r=0.114, p=0.025).

CONCLUSION

In this case-control study, patients with MAGA and a maternal history of androgenetic alopecia were at risk of FPHL. Therefore, early screening may benefit these patients.

CXXC5 Mediates DHT-Induced Androgenetic Alopecia via PGD2

The number of people suffering from hair loss is increasing, and hair loss occurs not only in older men but also in women and young people. Prostaglandin D₂ (PGD₂) is a well-known alopecia inducer. However, the mechanism by which PGD₂ induces alopecia is poorly understood. In this study, we characterized CXXC5, a negative regulator of the Wnt/β-catenin pathway, as a mediator for hair loss by PGD₂. The hair loss by PGD₂ was restored by Cxxc5 knock-out or treatment of protein transduction domain-Dishevelled binding motif (PTD-DBM), a peptide activating the Wnt/β-catenin pathway via interference with the Dishevelled (Dvl) binding function of CXXC5. In addition, suppression of neogenic hair growth by PGD₂ was also overcome by PTD-DBM treatment or Cxxc5 knock-out as shown by the wound-induced hair neogenesis (WIHN) model. Moreover, we found that CXXC5 also mediates DHT-induced hair loss via PGD₂. DHT-induced hair loss was alleviated by inhibition of both GSK-3β and CXXC5 functions. Overall, CXXC5 mediates the hair loss by the DHT-PGD₂ axis through suppression of Wnt/β-catenin signaling.

Biochemical and Structural Characteristics, Gene Regulation, Physiological, Pathological and Clinical Features of Lipocalin-Type Prostaglandin D2 Synthase as a Multifunctional Lipocalin

Lipocalin-type prostaglandin (PG) D₂ synthase (L-PGDS) catalyzes the isomerization of PGH₂, a common precursor of the two series of PGs, to produce PGD₂. PGD₂ stimulates three distinct types of G protein-coupled receptors: (1) D type of prostanoid (DP) receptors involved in the regulation of sleep, pain, food intake, and others; (2) chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2) receptors, in myelination of peripheral nervous system, adipocyte differentiation, inhibition of hair follicle neogenesis, and others; and (3) F type of prostanoid (FP) receptors, in dexamethasone-induced cardioprotection. L-PGDS is the same protein as β-trace, a major protein in human cerebrospinal fluid (CSF). L-PGDS exists in the central nervous system and male genital organs of various mammals, and human heart; and is secreted into the CSF, seminal plasma, and plasma, respectively. L-PGDS binds retinoic acids and retinal with high affinities (Kd < 100 nM) and diverse small lipophilic substances, such as thyroids, gangliosides, bilirubin and biliverdin, heme, NAD(P)H, and PGD₂, acting as an extracellular carrier of these substances. L-PGDS also binds amyloid β peptides, prevents their fibril formation, and disaggregates amyloid β fibrils, acting as a major amyloid β chaperone in human CSF. Here, I summarize the recent progress of the research on PGD₂ and L-PGDS, in terms of its “molecular properties,” “cell culture studies,” “animal experiments,” and “clinical studies,” all of which should help to understand the pathophysiological role of L-PGDS and inspire the future research of this multifunctional lipocalin.

The prostaglandin synthases, COX-2 and L-PGDS, mediate prostate hyperplasia induced by low-dose bisphenol A

This study aimed to identify prostaglandin synthases (PGS) that mediate bisphenol A (BPA)-induced prostatic hyperplasia and explore their underlying mechanisms. In an in vivo study, male adult Sprague–Dawley rats were treated with different concentrations of BPA (10, 30, 90, or 270 μg/kg, i.g., daily), or with vehicle for 4 weeks. Results revealed that low-dose BPA induced prostatic hyperplasia with increased PCNA/TUNEL ratio. It significantly upregulated the expression of cyclooxygenase-2 (COX-2) and NF-κB in the dorsolateral prostate (P < 0.05) and the expression of lipocalin-type prostaglandin D synthase (L-PGDS) in ventral prostate (P < 0.05). The level of estradiol (E₂)/testosterone (T) and expression of androgen receptor (AR) and estrogen receptor α (ERα) were also altered. In vitro studies showed that low-dose BPA (0.1–10 nM) promoted the proliferation of human prostate fibroblasts and epithelial cells, and significantly upregulated the expression of COX-2 and L-PGDS in the cells. The two types of cell proliferation induced by BPA were inhibited by COX-2 inhibitor (NS398) and L-PGDS inhibitor (AT56), with increased apoptosis level. These findings suggested that COX-2 and L-PGDS could mediate low-dose BPA-induced prostatic hyperplasia through pathways involved in cell proliferation and apoptosis, which might be related to the functions of ERα and AR. The role of COX-2/NF-κB pathway in dorsolateral prostate requires further research.

Expression of prostaglandin (PG) D synthase lipocalin and hematopoietic type and PG D receptor during restart of spermatogenesis following downregulation using a slow release GnRH agonist implant in the dog

Prostaglandin D and the associated prostaglandin D synthases (PGDS) and receptor (DP) are considered to be involved in spermatogenesis. However, the interplay of the PGDS-DP system in male reproduction is far from being understood. The expression of PGDS lipocalin (L) and hematopoietic (H) type and DP was studied in the GnRH agonist-downregulated canine testis (week, w 0) and during recrudescence of spermatogenesis after implant removal (w 3, 6, 9, 12). H-PGDS, L-PGDS and DP were present in the adult (CG), juvenile (JG) and downregulated canine testis at the mRNA level. PGDS immunohistochemistry revealed positive staining in the cytoplasm of Leydig cells (LCs) of all samples i.e., no difference between groups. mRNA expression (ratio) of L-, H-PGDS and DP did not differ between groups w 0-12 and CG. In contrast, significant differences were found for L-PGDS (p = 0.0388), H-PGDS (p < 0.001) and DP (p < 0.001) for the groups at downregulation (w0, suprelorin group, SG, profact group, PRG) compared with the control groups (JG, CG). L-PGDS expression was lowest in JG, whereas H-PGDS was significantly lower in CG compared with JG and at downregulation (p < 0.001 to p < 0.01). The highest ratio for H-PGDS and DP was observed in the dogs treated with buserelin acetate (PRG). Our data show that the PGDS-DP system is expressed in juvenile and adult canine testes and that downregulation of the testicular endocrine and germinative function significantly affects H-PGDS, L-PGDS and DP mRNA expression indicating a role in the regulation of spermatogenesis.

Prostaglandin D2 Uses Components of ROS Signaling to Enhance Testosterone Production in Keratinocytes

Elevated levels of prostaglandin D2 (PGD2) have been shown to be present in the bald scalp of androgenic alopecia (AGA) patients and to functionally inhibit hair growth. However, its precise mechanism in AGA has yet to be clearly defined. Although testosterone plays a critical role in the initiation and progression of AGA, the existence of a possible link between PGD2 and testosterone in skin has not been investigated. Here we show that human keratinocytes treated with PGD2 show enhanced capacity to convert the weak androgen, androstenedione, to testosterone. At the same time, treatment with PGD2 induced reactive oxygen species as indicated by generation of the lipid peroxidation product, 4-hydroxynonenal. To determine whether these two events are linked, we used the reactive oxygen species scavenger N-acetyl-cysteine, which blocked the enhanced testosterone production from PGD2-treated keratinocytes. Our study suggests the existence of a possible crosstalk between the PGD2-reactive oxygen species axis and testosterone metabolism in keratinocytes. Thus, we propose that AGA patients might benefit from the use of N-acetyl-cysteine or other antioxidants as a supplement to currently available or emerging AGA therapies such as finasteride, minoxidil, and PGD2 receptor blockers.

Does prostaglandin D2 hold the cure to male pattern baldness?

Lipids in the skin are the most diverse in the entire human body. Their bioactivity in health and disease is underexplored. Prostaglandin D2 has recently been identified as a factor which is elevated in the bald scalp of men with androgenetic alopecia (AGA) and has the capacity to decrease hair lengthening. An enzyme which synthesizes it, prostaglandin D2 synthase (PTGDS or lipocalin-PGDS), is hormone responsive in multiple other organs. PGD2 has two known receptors, GPR44 and PTGDR. GPR44 was found to be necessary for the decrease in hair growth by PGD2 . This creates an exciting opportunity to perhaps create novel treatments for AGA, which inhibit the activity of PTGDS, PGD2 or GPR44. This review discusses the current knowledge surrounding PGD2 , and future steps needed to translate these findings into novel therapies for patients with AGA.

Cloning and primary characterizations of rLcn9, a new member of epididymal lipocalins in rat

Lipocalins are a structurally conserved and diversely functional family of proteins that are of potential importance in epididymis functions. The rat Lcn9 gene was cloned by in silico methods and genome walking based on homology to the rhesus monkey epididymal ESC513 and its polyclonal antisera were prepared. The rat Lcn9 gene is located on chromosome 3p13 spanning 7 exons, contains 2.3 kb and encodes 179 amino acids with a 17-amino acid signal peptide. Northern blot, western blot, and immunohistochemical staining analysis revealed that rat Lcn9 was a novel epididymis-specific gene, expressed selectively in the proximal caput region, influenced by luminal fluid testicular factors. Moreover, Lcn9 protein was modified by N-glycosylation and bound on the postacrosomal domain of caput sperm. In conclusion, the rat Lcn9 exhibited tissue-, region-, and temporal-specific expression patterns and its expression was regulated by luminal testicular factors. Its potential roles in sperm maturation are discussed.

Prostaglandin D2 inhibits hair growth and is elevated in bald scalp of men with androgenetic alopecia

Testosterone is necessary for the development of male pattern baldness, known as androgenetic alopecia (AGA); yet, the mechanisms for decreased hair growth in this disorder are unclear. We show that prostaglandin D(2) synthase (PTGDS) is elevated at the mRNA and protein levels in bald scalp compared to haired scalp of men with AGA. The product of PTGDS enzyme activity, prostaglandin D(2) (PGD(2)), is similarly elevated in bald scalp. During normal follicle cycling in mice, Ptgds and PGD(2) levels increase immediately preceding the regression phase, suggesting an inhibitory effect on hair growth. We show that PGD(2) inhibits hair growth in explanted human hair follicles and when applied topically to mice. Hair growth inhibition requires the PGD(2) receptor G protein (heterotrimeric guanine nucleotide)-coupled receptor 44 (GPR44), but not the PGD(2) receptor 1 (PTGDR). Furthermore, we find that a transgenic mouse, K14-Ptgs2, which targets prostaglandin-endoperoxide synthase 2 expression to the skin, demonstrates elevated levels of PGD(2) in the skin and develops alopecia, follicular miniaturization, and sebaceous gland hyperplasia, which are all hallmarks of human AGA. These results define PGD(2) as an inhibitor of hair growth in AGA and suggest the PGD(2)-GPR44 pathway as a potential target for treatment.

The role of androgen and androgen receptor in skin-related disorders

Androgen and androgen receptor (AR) may play important roles in several skin-related diseases, such as androgenetic alopecia and acne vulgaris. Current treatments for these androgen/AR-involved diseases, which target the synthesis of androgens or prevent its binding to AR, can cause significant adverse side effects. Based on the recent studies using AR knockout mice, it has been suggested that AR and androgens play distinct roles in the skin pathogenesis, and AR seems to be a better target than androgens for the treatment of these skin diseases. Here, we review recent studies of androgen/AR roles in several skin-related disorders, including acne vulgaris, androgenetic alopecia and hirsutism, as well as cutaneous wound healing.

Estradiol regulation of lipocalin-type prostaglandin D synthase promoter activity: evidence for direct and indirect mechanisms

In the CNS, lipocalin-type prostaglandin D synthase (L-PGDS) is predominantly a non-neuronal enzyme responsible for the production of PGD(2), an endogenous sleep promoting substance. We have previously demonstrated that estradiol differentially regulates L-PGDS transcript levels in the rodent brain. In hypothalamic nuclei, estradiol increases L-PGDS transcript expression, whereas in the ventrolateral preoptic area L-PGDS gene expression is reduced after estradiol treatment. In the present study, we have used an immortalized glioma cell line transfected with a L-PGDS reporter construct and estrogen receptor (ER) alpha and ERbeta expression plasmids to further elucidate the mechanisms underlying estradiol regulation of L-PGDS gene expression. We found that physiologically relevant concentrations of estradiol evoked an inverted U response in cells expressing ERalpha. The most effective concentration of estradiol (10(-11)M) increased the promoter activity 3-fold over baseline. Expression of ERbeta did not increase activity over control and when ERbeta was co-expressed with ERalpha there was a significant attenuation of the promoter activity. While ERalpha significantly increased L-PGDS promoter activity, our previous in vivo studies demonstrate a greater magnitude of change in L-PGDS gene expression in the presences of estradiol. This led us to ask whether estradiol is signaling via a paracrine factor released by the neighboring neurons. Conditioned media from estradiol treated neurons applied to the glioma cell line resulted in a significant 7-fold increase in L-PGDS promoter activity supporting the possibility that neuronal-glial interactions are involved in estradiol regulation of L-PGDS.

Differential expression and regulation of integral membrane protein 2b in rat male reproductive tissues

AIM

To examine the expression and regulation of integral membrane protein 2b (Itm2b) in rat male reproductive tissues during sexual maturation and under different treatments by in situ hybridization.

METHODS

Testis, epididymis, and vas deferens were collected on days 1-70 to examine Itm2b expression during sexual maturation. To further examine the regulation of Itm2b, adult rats underwent surgical castration and cryptorchidism. Ethylene dimethane sulfonate and busulfan treatments were carried out to test the regulation of Itm2b after destruction of Leydig cells and germ cells.

RESULTS

In testis, Itm2b expression was moderately detected in the adluminal area of seminiferous cords on days 1-10, and detected at a low level in the spermatogonia on days 20 and 30. The Itm2b level was markedly increased in Leydig cells from day 20 to day 70. In epididymis and vas deferens, Itm2b was detected from neonate to adults, and the signal gradually increased in accordance with sexual maturation. Itm2b expression was significantly downregulated in epididymis and vas deferens of castrated rats, and strongly stimulated when castrated rats were treated with testosterone. Cryptorchidism led to a significant decline of Itm2b expression in testis and caput epididymis. Itm2b expression in epididymis and vas deferens was significantly decreased after the Leydig cells were destroyed by ethylene dimethane sulfonate. Busulfan treatment produced no obvious change in Itm2b expression in epididymis or vas deferens.

CONCLUSION

Our data suggested that Itm2b expression is upregulated by testosterone and might play a role in rat male reproduction.

Identification of transcripts related to high egg production in the chicken hypothalamus and pituitary gland

To identify transcripts related to high egg production expressed specifically in the hypothalamus and pituitary gland of the chicken, two subtracted cDNA libraries were constructed. Two divergently selected strains of Taiwan Country Chickens (TCCs), B (sire line) and L2 (dam line) were used; they had originated from a single population and were further subjected (since 1982) to selection for egg production to 40 wk of age and body weight/comb size, respectively. A total of 324 and 370 clones were identified from the L2-B (L2-subtract-B) and the B-L2 subtracted cDNA libraries, respectively. After sequencing and annotation, 175 and 136 transcripts that represented 53 known and 65 unknown non-redundant sequences were characterized in the L2-B subtracted cDNA library. Quantitative reverse-transcription (RT)-PCR was used to screen the mRNA expression levels of 32 randomly selected transcripts in another 78 laying hens from five different strains. These strains included the two original strains (B and L2) used to construct the subtracted cDNA libraries and an additional three commercial strains, i.e., Black- and Red-feather TCCs and Single-Comb White Leghorn (WL) layer. The mRNA expression levels of 16 transcripts were significantly higher in the L2 than in the B strain, whereas the mRNA expression levels of nine transcripts, BDH, NCAM1, PCDHA@, PGDS, PLAG1, PRL, SAR1A, SCG2 and STMN2, were significantly higher in two high egg production strains, L2 and Single-Comb WL; this indicated their usefulness as molecular markers of high egg production.

Suppression of prostate tumor cell growth by stromal cell prostaglandin D synthase-derived products

Stromal-epithelial interactions and the bioactive molecules produced by these interactions maintain tissue homeostasis and influence carcinogenesis. Bioactive prostaglandins produced by prostaglandin synthases and secreted by the prostate into seminal plasma are thought to support reproduction, but their endogenous effects on cancer formation remain unresolved. No studies to date have examined prostaglandin enzyme production or prostaglandin metabolism in normal prostate stromal cells. Our results show that lipocalin-type prostaglandin D synthase (L-PGDS) and prostaglandin D2 (PGD2) metabolites produced by normal prostate stromal cells inhibited tumor cell growth through a peroxisome proliferator-activated receptor gamma (PPARgamma)-dependent mechanism. Enzymatic products of stromal cell L-PGDS included high levels of PGD2 and 15-deoxy-delta(12,14)-PGD2 but low levels of 15-deoxy-delta(12,14)-prostaglandin J2. These PGD2 metabolites activated the PPARgamma ligand-binding domain and the peroxisome proliferator response element reporter systems. Thus, growth suppression of PPARgamma-expressing tumor cells by PGD2 metabolites in the prostate microenvironment is likely to be an endogenous mechanism involved in tumor suppression that potentially contributes to the indolence and long latency period of this disease.