Reduced urea flux across the blood-testis barrier and early maturation in the male reproductive system in UT-B-null mice

2007 ◽  
Vol 293 (1) ◽  
pp. C305-C312 ◽  
Author(s):  
Lirong Guo ◽  
Dan Zhao ◽  
Yuanlin Song ◽  
Yan Meng ◽  
Huashan Zhao ◽  
...  
Keyword(s):  
Sertoli Cells ◽  
Reproductive System ◽  
Molecular Mechanisms ◽  
Male Reproductive System ◽  
Testis Weight ◽  
Wild Type ◽  
Early Puberty ◽  
Early Maturation ◽  
Androgen Binding

A urea-selective urine-concentrating defect was found in transgenic mice deficient in urea transporter (UT)-B. To determine the role of facilitated urea transport in extrarenal organs expressing UT-B, we studied the kinetics of [14C]urea distribution in UT-B-null mice versus wild-type mice. After renal blood flow was disrupted, [14C]urea distribution was selectively reduced in testis in UT-B-null mice. Under basal conditions, total testis urea content was 335.4 ± 43.8 μg in UT-B-null mice versus 196.3 ± 18.2 μg in wild-type mice ( P < 0.01). Testis weight in UT-B-null mice (6.6 ± 0.8 mg/g body wt) was significantly greater than in wild-type mice (4.2 ± 0.8 mg/g body wt). Elongated spermatids were observed earlier in UT-B-null mice compared with wild type mice on day 24 versus day 32, respectively. First breeding ages in UT-B knockout males (48 ± 3 days) were also significantly earlier than that in wild-type males (56 ± 2 days). In competing mating tests with wild-type males and UT-B-null males, all pups carried UT-B-targeted genes, which indicates that all pups were produced from breeding of UT-B-null males. Experiments of the expression of follicle-stimulating hormone receptor (FSHR) and androgen binding protein (ABP) indicated that the development of Sertoli cells was also earlier in UT-B-null mice than that in wild-type mice. These results suggest that UT-B plays an important role in eliminating urea produced by Sertoli cells and that UT-B deletion causes both urea accumulation in the testis and early maturation of the male reproductive system. The UT-B knockout mouse may be a useful experimental model to define the molecular mechanisms of early puberty.

scholarly journals X chromosome choice occurs independently of asynchronous replication timing

2005 ◽  
Vol 168 (3) ◽  
pp. 365-373 ◽  
Author(s):  
Joost Gribnau ◽  
Sandra Luikenhuis ◽  
Konrad Hochedlinger ◽  
Kim Monkhorst ◽  
Rudolf Jaenisch
Keyword(s):  
X Chromosome ◽  
Molecular Mechanisms ◽  
Replication Timing ◽  
S Phase ◽  
X Inactivation ◽  
Wild Type ◽  
Gene Deletions ◽  
Asynchronous Replication ◽  
Skewed X Inactivation

In mammals, dosage compensation is achieved by X chromosome inactivation in female cells. Xist is required and sufficient for X inactivation, and Xist gene deletions result in completely skewed X inactivation. In this work, we analyzed skewing of X inactivation in mice with an Xist deletion encompassing sequence 5 KB upstream of the promoter through exon 3. We found that this mutation results in primary nonrandom X inactivation in which the wild-type X chromosome is always chosen for inactivation. To understand the molecular mechanisms that affect choice, we analyzed the role of replication timing in X inactivation choice. We found that the two Xist alleles and all regions tested on the X chromosome replicate asynchronously before the start of X inactivation. However, analysis of replication timing in cell lines with skewed X inactivation showed no preference for one of the two Xist alleles to replicate early in S-phase before the onset of X inactivation, indicating that asynchronous replication timing does not play a role in skewing of X inactivation.

248. Oestrogen receptor beta is involved in the regulation of Leydig cell number in the mouse

2005 ◽  
Vol 17 (9) ◽  
pp. 99
Author(s):  
M. Gould ◽  
H. D. Nicholson
Keyword(s):  
Leydig Cell ◽  
Sertoli Cells ◽  
Leydig Cells ◽  
Oestrogen Receptor ◽  
Physiological Role ◽  
Plasma Testosterone ◽  
Testis Weight ◽  
Wild Type ◽  
Significant Difference ◽  
Receptor Beta

Recent evidence suggests that oestrogen plays a physiological role in the testis. Both oestrogen receptor alpha and oestrogen receptor beta (ERb) are present in the testis and administration of oestrogen has been shown to inhibit the development of Sertoli, Leydig and germ cells. This study investigates the effect of ERb on the testis using ERb knockout mice (bERKO). Adult male bERKO mice (n=8) and their wild-type littermates (n=7) were killed at 11 weeks postpartum. One testis from each animal was fixed in Bouin’s fluid and embedded. Each testis was fractionated and thick sections cut and stained with PAS. The optical disector method was used to count the number of Leydig cells, Sertoli cells, spermatogonia, spermatocytes and spermatids in each testis. Trunk blood was collected and plasma testosterone concentrations measured by radioimmunoassay. No significant differences in body or testis weight were seen between the bERKO or wild-type mice. Similar numbers of Sertoli cells, spermatogonia, spermatocytes and spermatids were also observed between the two groups. The number of Leydig cells was significantly increased in bERKO mice compared with their wild-type littermates (P < 0.05). Despite the increased number of Leydig cells in the bERKO mice there was no significant difference in plasma testosterone concentrations in this group compared to the wild-type mice. Oestrogen has been reported to inhibit proliferation of adult-type Leydig cells and to inhibit steroidogenesis. This study suggests that the regulation of Leydig cell proliferation may be mediated by ERb. The presence of normal circulating testosterone concentrations in bERKO mice suggests that the effects of oestrogen on steroidogenesis are not brought about by ERbeta.

PHD Domain Deletion Mutations of ASXL1 Promote Myeloid Leukemia Transformation Through Epigenetic Dysregulation and Inhibit Megakaryocytic Differentiation Through the Inactivation of FOSB in K562 Cells.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2393-2393 ◽  
Author(s):  
Rabindranath Bera ◽  
Der-Cherng Liang ◽  
Ming-Chun Chiu ◽  
Ying-Jung Huang ◽  
Sung-Tzu Liang ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
Molecular Mechanisms ◽  
Blast Crisis ◽  
K562 Cells ◽  
Specific Cell ◽  
Wild Type ◽  
Megakaryocytic Differentiation ◽  
Deletion Mutations ◽  
Phd Domain

Abstract Abstract 2393 Somatic mutations of ASXL1 gene have been described in patients with myeloid malignancies and were associated with inferior outcomes. ASXL1 mutations have also been detected in myeloid blast crisis of chronic myeloid leukemia (CML) patients. The mechanisms of acute myeloid leukemia (AML) transformation and functional role of ASXL1 mutations in the leukemogenesis remain to be determined. Recently, we identified PHD domain deletion mutations (R693X and L885X) in patients with CML in myeloid blast crisis and/or AML with minimal differentiation (M0). In the present study, we aimed to investigate the role of PHD domain deletion mutations in the pathogenesis of AML transformation. The K562 cells carrying Philadelphia chromosome, serves as a model to study the molecular mechanisms associated with leukemogenesis. Our result showed that R693X/L885X mutations inhibited PMA-treated megakaryocytic differentiation with the change of physiological characteristic features and suppressed the induction of CD61, a specific cell surface marker of megakaryocytes. We also found that FOSB, a member of Fos family of AP-1 transcription factors was down-regulated in K562 cells expressing R693X and L885X compared to wild-type ASXL1 during PMA-mediated megakaryocytic differentiation. Examination of intracellular signaling pathways showed that the mutant ASXL1 protein prevented PMA-induced megakaryocytic differentiation through the inactivation of ERK, AKT and STAT5 which are required for differentiation. Further, ASXL1 depletion by shRNA in K562 cells led to enhanced cell proliferation, increased colony formation and impaired PMA-mediated differentiation. Previous studies in Drosophila had revealed that Asxl forms the protein complexes of both Trithorax and Polycomb groups that are required for maintaining chromatin in both activated and repressed transcriptional states. By using Western blot analysis, we demonstrated that PHD domain deletion mutations of ASXL1 significantly suppressed the transcriptionally repressive mark H3K27 trimethylation, however no effect on methylated H3K4 (H3K4me2 and H3K4me3), an active histone mark in K562 cells. Co-immunoprecipitation analysis revealed that wild-type, but not PHD domain deletion mutations of ASXL1 interact with EZH2, a member of the polycomb repressive complex 2 (PRC2). Importantly, PHD deletion mutations or downregulation of ASXL1 resulted in the suppression of EZH2 in K562 cells. Our study demonstrated that PHD deletion mutations of ASXL1 resulted in a loss-of-function which exhibited direct effects on the proliferation and differentiation and also proposed a specific role for ASXL1 in epigenetic regulation of gene expression in K562 cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Sperm oxidative stress: clinical significance and management

2021 ◽  
pp. 19-27
Author(s):  
S. I. Gamidov ◽  
T. V. Shatylko ◽  
A. Yu. Popova ◽  
N. G. Gasanov ◽  
R. S. Gamidov
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Reproductive System ◽  
Molecular Mechanisms ◽  
Assisted Reproductive Technologies ◽  
Reactive Oxygen ◽  
Reproductive Technologies ◽  
Male Reproductive System ◽  
Antioxidant Systems ◽  
Oxygen Species

Oxidative stress is one of the leading causes of sperm dysfunction. Excessive amounts of reactive oxygen species can damage sperm membranes and disrupt their DNA integrity, which affects not only the likelihood of getting pregnant naturally, but also the clinical outcomes of assisted reproductive technologies and the risk of miscarriage. Sperm cells are extremely vulnerable to oxidative stress, given the limited functional reserve of their antioxidant systems and the DNA repair apparatus. Lifestyle factors, most of which are modifiable, often trigger generation of reactive oxygen species.  Both the lifestyle modification and use of antioxidant dietary supplements are adequate and compatible ways to combat male oxidative stress-associated infertility. The search for other internal and external sources of reactive oxygen species, the identification of the etiology of oxidative stress and treatment of respective diseases are necessary for the successful regulation of redox processes in the male reproductive system in clinical practice, which is required not only to overcome infertility, but also to prevent induced epigenetic disorders in subsequent generations. The article presents the analysis of the molecular mechanisms of male idiopathic infertility. The authors provide an overview of how to prevent oxidative stress as one of the causes of subfebrile fever. The article provides an overview of modern therapeutics, as well as the options for eliminating the consequences of the effect of reactive oxygen species on spermatogenesis and male reproductive system in general.

scholarly journals Tetrapeptides Modelled to the Androgen Binding Site of ZIP9 Stimulate Expression of Tight Junction Proteins and Tight Junction Formation in Sertoli Cells

Biology ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 55
Author(s):  
Marie-Louise Möller ◽  
Ahmed Bulldan ◽  
Georgios Scheiner-Bobis
Keyword(s):  
Androgen Receptor ◽  
Tight Junction ◽  
Binding Site ◽  
Sertoli Cells ◽  
Alternative Pathway ◽  
Tight Junction Formation ◽  
Associated Proteins ◽  
A Cell ◽  
Androgen Binding

Androgens stimulate the expression of tight junction (TJ) proteins and the formation of the blood–testis barrier (BTB). Interactions of testosterone with the zinc transporter ZIP9 stimulate the expression of TJ-forming proteins and promote TJ formation in Sertoli cells. In order to investigate androgenic effects mediated by ZIP9 but not by the nuclear androgen receptor (AR), the effects of three tetrapeptides fitting the androgen binding site of ZIP9 were compared with those induced by testosterone in a Sertoli cell line expressing ZIP9 but not the AR. Three tetrapeptides and testosterone displaced testosterone-BSA-FITC from the surface of 93RS2 cells and stimulated the non-classical testosterone signaling pathway that includes the activation of Erk1/2 kinases and transcription factors CREB and ATF-1. The expression of the TJ-associated proteins ZO-1 and claudin-5 was triggered as was the re-distribution of claudin-1 from the cytosol to the membrane and nucleus. Furthermore, TJ formation was stimulated, indicated by increased transepithelial electrical resistance. Silencing ZIP9 expression by siRNA prevented all of these responses. These results are consistent with an alternative pathway for testosterone action at the BTB that does not involve the nuclear AR and highlight the significant role of ZIP9 as a cell-surface androgen receptor that stimulates TJ formation.

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