Septins belong to a family of polymerizing GTP-binding proteins that are required for many cellular functions, such as membrane compartmentalization, vesicular trafficking, mitosis, and cytoskeletal remodeling. One family member, septin12, is expressed specifically in the testis. In this study, we found septin12 expressed in multiple subcellular compartments during terminal differentiation of mouse germ cells. In humans, the testicular tissues of men with either hypospermatogenesis or maturation arrest had lower levels of SEPTIN12 transcripts than normal men. In addition, increased numbers of spermatozoa with abnormal head, neck, and tail morphologies lacked SEPT12 immunostaining signals, as compared with normal spermatozoa. To elucidate the role of septin12, we generated 129 embryonic stem cells containing a septin12 mutant allele with a deletion in the exons that encode the N-terminal GTP-binding domain. Most chimeras derived from the targeted embryonic stem cells were infertile, and the few fertile chimeras only produced offspring with a C57BL/6 background. Semen analysis of the infertile chimeras showed a decreased sperm count, decreased sperm motility, and spermatozoa with defects involving all subcellular compartments. The testicular phenotypes included maturation arrest of germ cells at the spermatid stage, sloughing of round spermatids, and increased apoptosis of germ cells. Electron microscopic examination of spermatozoa showed misshapen nuclei, disorganized mitochondria, and broken acrosomes. Our data indicate that Septin12 expression levels are critical for mammalian spermiogenesis.
Septins are members of the GTPase superfamily, which has been implicated in diverse cellular functions including cytokinesis and morphogenesis. Septin 12 (SEPT12) is a testis-specific gene critical for the terminal differentiation of male germ cells. We report the identification of two missense SEPT12 mutations, c.266C>T/p.Thr89Met and c.589G>A/p.Asp197Asn, in infertile men. Both mutations are located inside the GTPase domain and may alter the protein structure as suggested by in silico modeling. The p.Thr89Met mutation significantly reduced guanosine-5'-triphosphate (GTP) hydrolytic activity, and the p.Asp197Asn mutation (SEPT12(D197N)) interfered with GTP binding. Both mutant SEPT12 proteins restricted the filament formation of the wild-type SEPT12 in a dose-dependent manner. The patient carrying SEPT12(D197N) presented with oligoasthenozoospermia, whereas the SEPT12(T89M) patient had asthenoteratozoospermia. The characteristic sperm pathology of the SEPT12(D197N) patient included defective annulus with bent tail and loss of SEPT12 from the annulus of abnormal sperm. Our finding suggests loss-of-function mutations in SEPT12 disrupted sperm structural integrity by perturbing septin filament formation.
Prostaglandin (PG) E2 has been shown to stimulate steroidogenesis in ectopic endometriotic stromal cells and may be involved in the development of endometriosis since this disorder is highly estrogen dependent. The biosynthesis of PGE2 is controlled by the rate-limiting enzyme termed cyclooxygenase (COX). The objective of the current study was to investigate the expression of COX in peritoneal macrophages isolated from women with and without endometriosis, and to explore the effects of pro-inflammatory agents on COX expression in peritoneal macrophages. Using quantitative RT-PCR and Western blot analyses, we found that expression of COX-2 was markedly increased (P < 0.05) in peritoneal macrophages isolated from women with early or severe endometriosis, whereas expression of COX-1 was elevated only in the severe stage (P < 0.05). On the contrary, monocytes/macrophages purified from peripheral blood of patients with endometriosis had minimal or undetectable levels of COX-2, and this was not different from disease-free women. Treatment with interleukin-1beta, tumour necrosis factor-alpha or PGE2 caused a significant increase in COX-2 (P < 0.05) but not COX-1 expression in peritoneal macrophages isolated from disease-free women. In contrast, these agents had no substantial effect on COX-1 and COX-2 expression in peritoneal macrophages from women with endometriosis. In summary, expression of COX in peritoneal macrophages was associated with the severity of endometriosis. Elevated expression of both COX-1 and COX-2 in peritoneal macrophages may contribute to the increased peritoneal fluid PGE2 concentrations and may thus play an important role in the development of endometriosis.
This observation may help to explain the excessive response often seen during gonadotrophin administration in women with PCOS. We believe that a quantification study of the vascular flow, including the VI, FI, and VFI of the entire ovarian stroma using 3D power Doppler, is more accurate than the previously reported quantification analysis using 2D imaging, and may be a new parameter to assist in the ultrasound diagnosis of PCOS.
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