Genomic and post-genomic leads toward regulation of spermatogenesis

Declining male fertility without sign of any recovery and limited understanding about mechanisms involved in the intra-testicular regulation of spermatogenesis, withholding clinicians from delivering appropriate line of treatment, are serious causes of concern. Several infertile men are not amenable to treatment because hormonal deficiency or physical obstruction is not the underlying cause. A hope has been generated in the post genomic era where we can have information about the testicular genes and proteins which regulate germ cell division, differentiation and maturation in an interactive manner. Expression of some of these genes and proteins may be governed by classical hormones. However, if the genes are defective (naturally or acquired later in life), mere treatment with hormone(s), as is opted presently by clinicians, would not result into production of sperm. High throughput techniques and post genomic endeavors have generated plethora of data for fundamental and clinical andrology. Appropriate analyses and interlinking of these datasets may provide access to very precise information on a myriad of somatic and germ cell specific genes and proteins. Studies of functional genomics involving cell and age specific expression of some of these testicular genes will not only pin point precise role of certain biomolecules in various steps of spermatogenesis but it will also provide strong basis for the diagnosis and treatment of male infertility. In this review, we present some transcriptomic and proteomic information from various testicular somatic and germ cell studies and discuss how a systems biology approach may be brought in to meaningfully utilize the available information

The effect of IBMX and hormones on gene expression by rat Sertoli cells

Background: Sertoli cells (Sc) regulate spermatogenesis under the control of FSH and testosterone (T). Functional maturation of Sc for supporting the spermatogenic onset during pubertal development is prerequisite for male fertility. However, the effect of hormone driven maturational changes in Sc is not well known. Objectives and experimental model: In this present study we have compared hormone induced gene expression of immature and mature Sc isolated from neonatal (9-days old) and prepubertal (18-days-old) rat testes, respectively, to investigate the developmental difference of hormone responsiveness of Sc during postnatal maturation as well as influence of 3-isobutyl-1-methylxanthine (IBMX), a nonspecific inhibitor of phosphodiesterase in primary culture of Sc. Results and conclusion: Our results suggested that FSH responsiveness of Sc obtained from 18-days-old rats were more prominent in terms of augmentation of lactate, cAMP and gene transcription as compared to Sc from 9-days of age. Our result also indicated that although the use of IBMX in primary culture of Sc generates a better readout in terms of FSH induced cAMP response, the presence of such pharmacological agent mellows down FSH stimulated gene expression profile. Our data indicated further that immature Sc are capable of differentiating in vitro if cultured with continuous supplementation of FSH and T (in combination). Taken together, we also concluded that for accurate evaluation of the modulation of gene expression by hormones, use of IBMX should be avoided in primary cultures of Sc

Unilateral nevoid trichoepitheliomas on the neck: an unfamiliar presentation

Trichoepitheliomas are epidermal appendageal hamartomas, which usually present as solitary lesions; rarely multiple lesions may be present, mainly involving the centrofacial skin symmetrically. We report herein an adolescent male patient with multiple trichoepitheliomas, linearly arranged and dermatomal, present since birth, along the left side of the neck

Germ cell development in teleost gonads

Among vertebrate species, fishes are considered to be the most developmentally diverse taxa exhibiting remarkable gonadal plasticity with capacity of sex reversal. Sex determination in teleost fishes is governed via a complex regulatory network involving multiple genetic, environmental (temperature, population density, pH), social interaction/stress factors. Piscine germ-line originates as Primordial germ cells (PGC) from cleavage blastomeres/endoderm and gets specified by maternal inheritance of Vasa, Nanos, Tdrds, Dnd, Dazl etc and subsequently migrates to reach the embryonic gonadal primordium. Post-hatching, mitotically active germ cells (Gc) continue to proliferate via two distinct pathways-firstly, stem cell-like mode followed by meiosis-committed cystic division. In Japanese rice fish medaka, Oryzias latipes sex gets determined on the chromosomal basis, where XY becomes a male because of testicular Dmy transcription and XX develops as female owing to Gc restricted Foxl3 expression. Sex specific germ-line stem cell systems also have been found in adult O. latipes. Intriguingly in teleost fishes, the developmental fate of transplanted Gc do not depend on the sex of the donor rather solely relies upon the sex of the recipient. Furthermore, sexually mature piscine gonads remain developmentally plastic showing extensive responsiveness towards sex steroids. The critical regulation of gonadal differentiation is directed by female specific 17β-estradiol (E2) and bio-active male androgen 11-keto-testosretone (11-kT). Various transcription factors (TFs) e.g.- Dmrt1, DAX1, Ad4BP/SF-1, Foxl2 regulate the bio-conversion rate of testosterone (T) to either E2 or 11-kT. Similarly, multiple endocrine factors (EFs) e.g.- LH, FSH, E2, 11-kT and growth factors (GFs) e.g- AMH, GSDF, IGF-1/3, GDF-9/BMP-15 critically induce Gc differentiation to regulate the gametogenic output. In this article we have precisely discussed the endocrine regulation of Gc development during gonadal maturation of teleosts

Insufficient androgen and FSH signaling may be responsible for the azoospermia of the infantile primate testes despite exposure to an adult-like hormonal milieu

Background: In humans, as well as in other higher primates, the infantile testis is exposed to an adult-like hormonal milieu, but spermatogenesis is not initiated at this stage of primate development. In the present study, we examined the molecular basis of this intriguing infertile state of the primate testis. Methods: The integrity of androgen receptor (AR) and FSH receptor (FSHR) signaling pathways in primary cultures of Sertoli cells (Scs) harvested from azoospermic infant and spermatogenic pubertal monkey testes were investigated under identical in vitro hormonal conditions. In order to synchronously harvest Scs from early pubertal testis, the activation of testicular puberty was timed experimentally by prematurely initiating gonadotrophin secretion in juvenile animals with an intermittent infusion of gonadotrophin-releasing hormone. Results: While qRT–PCR demonstrated that AR and FSHR mRNA expression in Scs from infant and pubertal testes were comparable, androgen-binding and FSH-mediated cAMP production by infant Scs was extremely low. Compromised AR and FSHR signaling in infant Scs was further supported by the finding that testosterone (T) and FSH failed to augment the expression of the T responsive gene, claudin 11, and the FSH responsive genes, inhibin-βB, stem cell factor (SCF) and glial cell line-derived neurotrophic factor (GDNF) in Scs harvested at this stage of development. Conclusion: These results indicate that compromised AR and FSHR signaling pathways in Scs underlie the inability of the infant primate testis to respond to an endogenous hormonal milieu that later in development, at the time puberty, stimulates the initiation of spermatogenesis. This finding may have relevance to some forms of idiopathic infertility in men

Advantages of pulsatile hormone treatment for assessing hormone-induced gene expression by cultured rat Sertoli cells

In response to various hormonal (follicle-stimulating hormone [FSH] and testosterone [T]) and biochemical inputs, testicular Sertoli cells (Sc) produce factors that regulate spermatogenesis. A number of FSH- and T-responsive Sc-specific genes, necessary for spermatogenesis, have been identified to date. However, the hormone-induced in vitro expression pattern of most of these genes is reported to be inconsistent at various time points in primary rat Sc cultures. As a matter of convenience, cultured Sc are constantly exposed to hormones for a few hours to days in the reported literature, although Sc are exposed to pulsatile FSH and T in vivo. The major aim of the present study is to evaluate the advantage, if any, of the in vitro administration of pulsatile hormone (FSH and T in combination) treatment on gene expression of cultured Sc as compared with that of constant hormone treatment. Pulsatile treatment (a 30-min hormonal exposure every 3 h) mimicking the in vivo condition reveals a more prominent effect of hormones in augmenting gene expression as compared with constant treatment. Our results indicate that the expressions of Stem cell factor (Scf, only responsive to FSH), Claudin11 (only responsive to T) and Transferrin (both FSH- and T-responsive) mRNAs are significantly higher at 12 h upon pulsatile treatment than upon constant hormonal treatment. Maximal expression of relevant genes because of pulsatile treatment with hormones suggests that this protocol provides a more suitable premise for assessing hormone-induced gene expression in isolated Sc than one involving constant exposure to hormones

Calcified Keratoacanthoma with Tumoral Calcinosis in a 10-year-old Boy: A mere Co-incidence?

Keratoacanthoma (KA) is a rapidly evolving benign cutaneous tumor, occurring in elderly individuals with a tendency towards spontaneous regression and histopathologic similarity to squamous cell carcinoma. Tumoral calcinosis is an uncommon condition, associated with the deposition of painless calcific masses. The occurrence of these two conditions in the same patient is a rarity itself, whereas deposition of calcium within the KA lesion in our 13-year-old patient makes it even more intriguing. Such an association has been seldom reported in the literature, and this prompted the current report

Primers used for validation of microarray genes.

<p>Primers used for validation of microarray genes.</p

A switch in Sertoli cell responsiveness to FSH may be responsible for robust onset of germ cell differentiation during prepubartal testicular maturation in rats

FSH and Testosterone (T) regulate spermatogenesis via testicular Sertoli cells (Sc), which bear receptors for these hormones. Despite sufficient circulating levels of FSH and T postnatally, predominant appearance of spermatogonia B and spermatocytes is not discernible until 11 and 18 days of postnatal age, respectively, in rat testes. In an attempt to explore the underlying causes, we cultured Sc from neonatal (5- and 9-day-old) and prepubertal (12- and 19-day-old) rat testes and compared the status of FSH receptor (FSH-R) and androgen receptor (AR) signaling. Protein and mRNA levels of FSH-R and AR remained uniform in cultured Sc from all age groups. Androgen binding ability of AR was similar, and T-induced nuclear localization of AR was discernible in Sc from all age groups. Binding of FSH to FSH-R, subsequent production of cAMP, and mRNA of stem cell factor (SCF) and glial cell line-derived neurotrophic factor (GDNF), known to be essential for the robust differentiation of repopulating spermatogonia, were significantly augmented in prepubertal Sc compared with those in neonatal Sc. However, treatment of neonatal Sc with cholera toxin or forskolin, which stimulate cAMP production bypassing FSH-R, demonstrated a concomitant rise in SCF and GDNF mRNA expression, which was similar to the FSH-mediated rise observed in prepubertal Sc. These observations suggested that, during prepubertal Sc maturation, the ability of FSH-R to respond to FSH is significantly augmented and is associated with the robust differentiation of repopulating spermatogonia, and such a switch in Sc from FSH-resistant to FSH-responsive mode during prepubertal development may underlie the initiation of robust spermatogenesis