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Wenhui Su and Xinchun Liu

integrity ( Madara et al . 1986 , 1992 , Balda et al . 1993 ), but the regulatory pathways that associate actin skeleton to TJ assembly still need to be elucidated. In the seminiferous epithelium, filamentous actin (F-actin) bundles at the Sertoli cell

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María Noel Galardo, María Fernanda Riera, Eliana Herminia Pellizzari, Selva Beatriz Cigorraga and Silvina Beatriz Meroni

cells are absolutely necessary in order to provide an adequate and protected environment within the seminiferous tubules. Germ cells situated beyond the blood testis barrier need to rely on Sertoli cell production of factors that fuel germ cell

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S Palmero, P De Marco and E Fugassa

ABSTRACT

A polymerase chain reaction (PCR)-based assay was used to evaluate the expression of thyroid hormone receptor β mRNA in Sertoli cells isolated from both prepubertal rat and piglet testes. The expression of an mRNA coding for the functional thyroid hormone receptor β isoform, as established by the PCR assay, agrees with the presence of specific tri-iodothyronine (T3)-binding sites in the Sertoli cell nuclei of both species, as previously evaluated by displacement analysis. The results ratify the existence of a functional T3 receptor in the prepubertal testis and confirm the Sertoli cell as a specific target for thyroid hormone action on the developing testis. On the other hand, in both peripubertal rat (Palmero et al. 1988; Jannini et al. 1990) and piglet (Palmero et al. 1992) testes, high-affinity, low-capacity T3 binding sites have been specifically localised at the Sertoli cell level and TRal mRNA expression has been detected very recently in immature Sertoli cells (Jannini et al. 1994).

The aim of the present work was to test if, in prepubertal Sertoli cells isolated from both immature rat and piglet testes, the expression of an erbAβ mRNA specifically coding for the TR protein could be detected employing an highly sensitive polymerase chain reaction (PCR)-based assay.

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S. Palmero, M. Benahmed, A. M. Morera, P. Trucchi and E. Fugassa

ABSTRACT

The existence of nuclear tri-iodothyronine (T3) receptors in both Sertoli and Leydig cells isolated from immature piglet testes was investigated. The results demonstrated the presence of high-affinity (K d=1·09±0·25 nm), low-capacity (185±24pg T3/mg DNA) binding sites for T3 in nuclei from freshly isolated Sertoli cells. No specific binding for T3 was observed in nuclei isolated from Leydig cells. The localization of specific T3 receptors, which might mediate the onset of thyroid hormone action, at Sertoli cell level confirms that these cells are a target for thyroid hormone and strongly sustain the role of the thyroid in the regulation of testicular functions during postnatal development.

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Zhen-Yu She and Wan-Xi Yang

. (1990)   Sox9 Transcription factor Campomelic dysplasia XY sex reversal (LOF) Abnormal Sertoli cell differentiation, XY sex reversal (LOF); XX sex reversal (GOF) Foster et al . (1994) , Huang et al . (1999) , Vidal et al . (2001

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P Grasso and L E Reichert Jr

ABSTRACT

We have previously shown that a synthetic peptide amide corresponding to residues 1–15 of the human FSH β-subunit (hFSH-β-(1–15)) possesses structural characteristics and calcium-binding properties similar to the calcium-binding loops of calmodulin (CaM). The calcium-binding property of hFSH-β-(1–15) correlated well with its ability to stimulate uptake of calcium (as45 Ca2+) by cultured rat Sertoli cells and proteoliposomes enriched with bovine calf testis FSH receptors. A sequence found in the calcium-binding loops of CaM and a number of other calcium-binding proteins can be represented by the motif +−+−+−+−+−−+, where + represents a calcium-binding residue and − represents a non-binding residue. A sequence containing a similar motif appears in hFSHβ-(1–15) between residues 4 and 15: +−++−+−−−+−+. Using a synthetic peptide strategy, we undertook to determine whether the first three residues of hFSH-β-(1–15) were required to induce uptake of calcium by cultured rat Sertoli cells and FSH receptor-enriched proteoliposomes, and to assess whether rearrangement of the putative calcium-binding ligands (+) of hFSH-β-(1–15) to correspond to their linear sequence in CaM would enhance the ability of hFSH-β-(1–15) to induce calcium uptake in these two model systems. Our results indicate that (1) the amino terminal tripeptide of hFSH-β-(1–15), NSC, is not required for its effects on calcium influx and (2), although the putative calcium-binding loop of hFSH-β-(1–15) does not strictly adhere to the structural motif present in the calcium-binding loops of CaM, this does not adversely affect the potency of hFSH-β-(1–15) in the systems studied. In addition to providing a structural basis for understanding the affinity of hFSH-β-(1–15) for calcium, these studies suggest that the effects of FSH on calcium flux in Sertoli cells may involve a CaM-like region of its β-subunit.

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MF Riera, SB Meroni, EH Pellizzari and SB Cigorraga

Basic fibroblast growth factor (bFGF) belongs to the large set of intratesticular regulators that provide the fine tuning of cellular processes implicated in the maintenance of spermatogenesis. The aim of the present study was to determine the participation of mitogen-activated protein kinase (MAPK) and phosphatidyl inositol 3-kinase/protein kinase B (PI3K/PKB) pathways in bFGF regulation of Sertoli cell function. Twenty-day-old rat Sertoli cell cultures were used. Stimulation of the cultures with bFGF showed a time-dependent increment in phosphorylated MAPK and PKB levels that reached maximal values in 5-min incubations. MAPK kinase inhibitors U0126 (U) and PD98059 (PD) and a PI3K inhibitor wortmannin (W) were able to block the stimulatory effects of bFGF on phosphorylated MAPK and PKB levels respectively. The participation of MAPK- and PI3K/PKB-signaling pathways in the regulation by bFGF of two well-known Sertoli cell-differentiated functions, lactate and transferrin production, was next explored. As for lactate production, PD and W did not modify the ability of bFGF to stimulate lactate production. However, a combination of PD and W partially impaired the increase in lactate production elicited by bFGF. The participation of MAPK- and PI3K/PKB-signaling pathways in the regulation by bFGF of glucose uptake and lactate dehydrogenase (LDH) activity was also analysed. In this respect, it was observed that W markedly decreased basal and bFGF-stimulated glucose uptake and that U and PD did not modify it. On the other hand, U and PD decreased the stimulation of LDH activity by bFGF whereas W did not modify it. As for transferrin production, while both MAPK kinase inhibitors partially decreased the ability of bFGF to stimulate transferrin secretion, the PI3K inhibitor did not modify it. In summary, the results demonstrated that bFGF stimulates MAPK- and PI3K/PKB-dependent pathways in rat Sertoli cells. Moreover, these results showed that while bFGF utilizes the MAPK pathway to regulate transferrin production and LDH activity, it uses the PI3K/PKB pathway to regulate glucose transport into the cell.

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Wing-Yee Lui and Will M Lee

interactions between Sertoli cells and between Sertoli and germ cells are important for germ cell differentiation and these can be achieved via the precise organization of different types of cell junctions (for review, see Cheng & Mruk 2002 ). For instance

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M Vigier, M Weiss, M H Perrard, M Godet and P Durand

(RS) and in the expression of genes specific to PS or RS. Materials and methods Isolation and coculture of rat Sertoli cells and pachytene spermatocytes (PS) Sertoli cells and PS were isolated as previously

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M H Abel, D Baban, S Lee, H M Charlton and P J O'Shaughnessy

through direct action on the Sertoli cells ( McLachlan et al . 2002 ). The role of gonadotrophins is clearly seen in the hypogonadal ( hpg ) mouse that lacks GnRH ( Mason et al . 1986 ) and, consequently, has undetectable circulating levels of LH and FSH