Table of Contents

Volume 2, Issue 1

  January/February/March 2012

  Pages 1 - 68

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EDITORIAL

Open Access Article

Cell lines: Valuable tools or useless artifacts

Gurvinder Kaur and Jannette M. Dufour
Pages 1 - 5
http://dx.doi.org/10.4161/spmg.19885
Abstract | Full Text | PDF

Cell lines are often used in place of primary cells to study biological processes. However, care must be taken when interpreting the results as cell lines do not always accurately replicate the primary cells. In this article, we will briefly talk about advantages and disadvantages of cell lines and then discuss results using the mouse Sertoli cell line, MSC-1, compared with primary mouse Sertoli cells. MSC-1 cells resemble Sertoli cells morphologically and possess several biochemical markers associated with Sertoli cells. Studies have demonstrated that the function and regulation of retinoic acid receptor α (RARα) is similar between MSC-1 and rat Sertoli cells. However, MSC-1 cells lack some of the immune privilege properties associated with primary Sertoli cells, including survival in animals with a fully functional immune system. Therefore, it has to be kept in mind that cell lines do not behave identically with primary cells and should not be used to replace primary cells. In order to strengthen the findings, key control experiments using primary cells should always be performed.




VIEWS, COMMENTARIES & OPINIONS

Open Access Article

In search of suitable in vitro models to study germ cell movement across the blood-testis barrier

Dolores D. Mruk and C. Yan Cheng
Pages 6 - 10
http://dx.doi.org/10.4161/spmg.19878
Abstract | Full Text | PDF

The movement of preleptotene/leptotene spermatocytes across the blood-testis barrier, also known as the Sertoli cell barrier, during stages VIII to XI of the seminiferous epithelial cycle is one of the most important cellular events taking place in the mammalian testis. Without the passage of spermatocytes, spermatogenesis would be halted, resulting in transient or permanent sterility. Unfortunately, we have very little knowledge on how preleptotene/leptotene spermatocytes cross the blood-testis barrier. While we know cytokines, proteases and androgens to mediate Sertoli cell junction restructuring, most data continue to be derived from experiments using Sertoli cells cultured alone in two dimensions. Thus, additional in vitro models which include germ cells must come into use. In this Commentary, we hope to shed new light on how we may better study spermatocyte movement across the BTB.




REVIEWS

Open Access Article

Tissue, cell type and stage-specific ectopic gene expression and RNAi induction in the Drosophila testis

Helen White-Cooper
Pages 11 - 22
http://dx.doi.org/10.4161/spmg.19088
Abstract | Full Text | PDF

The Drosophila testis has numerous advantages for the study of basic cellular processes, as production of sperm requires a highly orchestrated and complex combination of morphological changes and developmentally regulated transitions. Experimental genetics using Drosophila melanogaster has advanced dramatically with the advent of systems for ectopic expression of genetic elements in specific cells. However the genetic tools used in Drosophila research have rarely been generated with the testes in mind, and the utility of relatively few systems has been documented for this tissue. Here I will summarize ectopic expression systems that are known to work for the testis, and provide advice for selection of the most appropriate expression system in specific experimental situations.

Open Access Article

Genetically engineered immune privileged Sertoli cells: A new road to cell based gene therapy

Gurvinder Kaur, Charles R. Long and Jannette M. Dufour
Pages 23 - 31
http://dx.doi.org/10.4161/spmg.19119
Abstract | Full Text | PDF

Sertoli cells are immune privileged cells, important for controlling the immune response to male germ cells as well as maintaining the tolerogenic environment in the testis. Additionally, ectopic Sertoli cells have been shown to survive and protect co-grafted cells when transplanted across immunological barriers. The survival of ectopic Sertoli cells has led to the idea that they could be used in cell based gene therapy. In this review, we provide a brief overview of testis immune privilege and Sertoli cell transplantation, factors contributing to Sertoli cell immune privilege, the challenges faced by viral vector gene therapy, the use of immune privileged cells in cell based gene therapy and describe several recent studies on the use of genetically engineered Sertoli cells to provide continuous delivery of therapeutic proteins.

Open Access Article

Models of in vitro spermatogenesis

Damien Hunter, Ravinder Anand-Ivell, Sandra Danner and Richard Ivell
Pages 32 - 43
http://dx.doi.org/10.4161/spmg.19383
Abstract | Full Text | PDF

Understanding the mechanisms that lead to the differentiation of male germ cells from their spermatogonial stem cells through meiosis to give rise to mature haploid spermatozoa has been a major quest for many decades. Unlike most other cell types this differentiation process is more or less completely dependent upon the cells being located within the strongly structured niche provided by mature Sertoli cells within an intact seminiferous epithelium. While much new information is currently being obtained through the application and description of relevant gene mutations, there is still a considerable need for in vitro models with which to explore the mechanisms involved. Not only are systems of in vitro spermatogenesis important for understanding the basic science, they have marked pragmatic value in offering ex vivo systems for the artificial maturation of immature germ cells from male infertility patients, as well as providing opportunities for the transgenic manipulation of male germ cells. In this review, we have summarized literature relating to simplistic culturing of germ cells, co-cultures of germ cells with other cell types, especially with Sertoli cells, cultures of seminiferous tubule fragments, and briefly mention the opportunities of xenografting larger testicular pieces. The majority of methods are successful in allowing the differentiation of small steps in the progress of spermatogonia to spermatozoa; few tolerate the chromosomal reduction division through meiosis, and even fewer seem able to complete the complex morphogenesis which results in freely swimming spermatozoa. However, recent progress with complex culture environments, such as 3-d matrices, suggest that possibly success is now not too far away.

Open Access Article

p70 S6 kinase and actin dynamics: A perspective

Carman K.M. Ip and Alice S.T. Wong
Pages 44 - 52
http://dx.doi.org/10.4161/spmg.19413
Abstract | Full Text | PDF

p70 S6 kinase (p70^S6K), a member of the AGC serine/threonine kinase family, was initially identified as a key player, together with its downstream effector S6, in the regulation of cellular growth and survival. The p70^S6K protein has emerged in recent years as a multifunctional protein which also regulates the actin cytoskeleton and thus plays a role in cell migration. This new function is through two important activities of p70^S6K, namely actin cross-linking and Rac1 and Cdc42 activation. The testis is critically dependent on an intricate balance of fundamental cellular processes such as adhesion, migration, and differentiation. It is increasingly evident that Rho GTPases and actin binding proteins play fundamental roles in regulating spermatogenesis within the testis. In this review, we will discuss current findings of p70^S6K in the control of actin cytoskeleton dynamics. In addition, the potential role of p70^S6K in spermatogenesis and testicular function will be highlighted.




REPORTS

Open Access Article

Electroacupuncture enhances spermatogenesis in rats after scrotal heat treatment

Jing Gao, Yan Zuo, Kam-Hei So, William S.B. Yeung, Ernest H.Y. Ng and Kai-Fai Lee
Pages 53 - 62
http://dx.doi.org/10.4161/spmg.19282
Abstract | Full Text | PDF

Spermatogenesis is regulated by a cascade of steroid regulated genes in the testis. Recent studies suggested that acupuncture may improve fertility in men with abnormal semen parameters. Yet, the underlying mechanisms in which acupuncture enhances spermatogenesis remain largely unknown. Here we used a scrotal heat-treated rat model to study the effect of electroacupuncture (EA) on recovery of spermatogenesis. In this model, spermatogenesis was disrupted by 30 min scrotal heat treatment at 43°C. Ten sessions of EA were given at Baihui (GV20), Guanyuan (CV4), Zusanli (ST36) and Sanyinjiao (SP6) from day 9 to day 36 post-treatment. Sperm motility and production, morphology of the germinal epithelium by Johnsen’s scoring, germ cell apoptosis by TUNEL staining, proliferation by proliferating cell nuclear antigen (PCNA) staining, as well as serum testosterone and inhibin B levels by immunoassays were evaluated on day 0, 1, 9, 25, 37, 46, 56 and 79. When compared with the heat-treated (H) group, the heat-treated plus EA (H⁺EA) group showed a significant increase (p < 0.05) in PCNA-positive cells and inhibin B levels on days 37 and 46, and a higher Johnsen’s score till day 56. On day 79, motile spermatozoa could be found in the vas deferens of H⁺EA group only. Consistently, there was a trend of improved motility and increased number of motile epididymal spermatozoa in the H⁺EA group than the H group; while apoptosis of germ cells and serum testosterone levels were similar between the two groups. Taken together, EA enhanced germ cell proliferation through improvement of Sertoli cell functions. This may facilitate the recovery of spermatogenesis and may restore normal semen parameters in subfertile patients.

Open Access Article

Focal adhesion proteins Zyxin and Vinculin are co-distributed at tubulobulbar complexes

J’Nelle S. Young and A. Wayne Vogl
Pages 63 - 68
http://dx.doi.org/10.4161/spmg.19391
Abstract | Full Text | PDF

Tubulobulbar complexes (TBCs) are actin-related double-membrane invaginations formed at intercellular junctions in the seminiferous epithelium of mammalian testis. They occur at basal junction complexes between neighboring Sertoli cells and at apical junctions between Sertoli cells and spermatids. They are proposed to internalize intercellular junctions during the translocation of spermatocytes from basal to adluminal compartments of the seminiferous epithelium, and during sperm release from Sertoli cells. Although TBCs are specific to the seminiferous epithelium, they morphologically resemble podosomes in osteoclasts. Previously, we have reported that a key group of proteins consisting of N-WASp, Arp2/3, cortactin and dynamin that occur at podosomes also is present at TBCs. Here we explore the prediction that zyxin, a focal adhesion protein known to be present at podosomes, also is present at apical TBCs. A rabbit polyclonal anti-zyxin antibody (B71) was used to label fixed fragments and frozen sections of testis. In both fragments and sections, B71 labeled tubular regions of TBCs at apical sites of attachment between Sertoli cells and spermatids, in addition to being localized at actin related intercellular adhesion junctions termed ectoplasmic specializations. Although the function of zyxin at TBCs has yet to be determined, the protein is known to interact with the cytoplasmic domain of integrins at focal adhesions, and integrins are known to be present in TBCs.