Laura Suomalainen

Nuclear Factor-κB Activation in Human Testicular Apoptosis

Apoptotic cell death plays an important role in limiting testicular germ cell population during spermatogenesis and its dysregulation has been shown to be associated with male infertility. The growing evidence on the role of the transcription factor nuclear factor (NF)-κB in controlling apoptosis prompted us to investigate NF-κB activity in the normal human testis and its role in testis tissue undergoing excessive apoptosis in vitro. In electrophoretic mobility shift assays, low-level constitutive NF-κB DNA-binding activity was found and, by immunostaining of the RelA and p50 NF-κB subunits, was localized to Sertoli cell nuclei. During in vitro-induced testicular apoptosis, the Sertoli cell nuclear NF-κB levels and whole seminiferous tubule NF-κB DNA-binding activity increased previous detection of germ cells undergoing apoptosis. The anti-inflammatory drug sulfasalazine effectively suppressed stress-induced NF-κB DNA binding and NF-κB-mediated IκBα gene expression. Importantly, concomitantly with inhibiting NF-κB, sulfasalazine blocked germ cell apoptosis. These results suggest that during testicular stress Sertoli cell NF-κB proteins exert proapoptotic effects on germ cells, which raises the possibility that pharmacological inhibition of NF-κB could be a therapeutic target in transient stress situations involving excessive germ cell death.

Protection from Radiation-Induced Male Germ Cell Loss by Sphingosine-1-Phosphate

Abstract Male germ cells are susceptible to radiation-induced injury, and infertility is a common problem after total-body irradiation. Here we investigated, first, the effects of irradiation on germ cells in mouse testis and, second, the role of sphingosine-1-phosphate (S1P) treatment in radiation-induced male germ cell loss. Irradiation of mouse testes mainly damaged the early developmental stages of spermatogonia. The damage was seen by means of DNA flow cytometry 21 days after irradiation as decreasing numbers of spermatocytes and spermatids with increasing amounts of ionizing radiation (0.1–2.0 Gy). Intratesticular injections of S1P given 1–2 h before irradiation (0.5 Gy) did not protect against short-term germ cell loss as measured by in situ end labeling of DNA fragmentation 16 h after irradiation. However, after 21 days, in the S1P-treated testes, the numbers of primary spermatocytes and spermatogonia at G2 (4C peak as measured by flow cytometry) were higher at all stages of spermatogenesis compared with vehicle-treated testes, indicating protection of early spermatogonia by S1P, whereas the spermatid (1C) populations were similar. In conclusion, S1P appears to protect partially (16%–47%) testicular germ cells against radiation-induced cell death. This warrants further studies aimed at development of therapeutic agents capable of blocking sphingomyelin-induced pathways of germ cell loss.

Sphingosine-1-Phosphate Inhibits Nuclear Factor κB Activation and Germ Cell Apoptosis in the Human Testis Independently of Its Receptors

Early apoptosis-inducing events are potentially important targets for preventing germ cell loss caused by external stress. The sphingolipid sphingosine-1-phosphate (S1P) is an important regulator of stress-induced apoptosis. It affects the cell as an intracellular signaling molecule or as a ligand to its cell membrane-bound S1P(1-5) receptors. We previously demonstrated that S1P inhibits stress-induced male germ cell death in vitro and in vivo. Here, we further define the mechanisms of S1P-mediated inhibition of male germ cell death. Using immunohistochemistry, we detected expression of the S1P(1) and S1P(2) receptors in the somatic Sertoli cells of the human testis. In a culture of human seminiferous tubules, S1P inhibited germ cell apoptosis, suppressed both nuclear factor kappaB (NF-kappaB) DNA-binding activity and expression of phosphorylated Akt, but did not affect activator protein-1 (AP-1) DNA-binding activity. Dihydro-S1P, which binds to and activates S1P receptors but has no direct intracellular effect, suppressed neither apoptosis nor NF-kappaB activity. These results suggest that S1P inhibits male germ cell apoptosis independently of its receptors, possibly by inhibiting the transcription factor NF-kappaB and Akt phosphorylation.

Effects of media exposure on adolescents traumatized in a school shooting

This study analyzes the impact of the media on adolescents traumatized in a school shooting. Participants were trauma-exposed students (n = 231) and comparison students (n = 526), aged 13-19 years. A questionnaire that included the Impact of Event Scale and a 36-item General Health Questionnaire was administered 4 months after the shooting. Being interviewed was associated with higher scores on the Impact of Event Scale (p = .005), but posttraumatic symptoms did not differ between those who refused to be interviewed and those not approached by reporters. Following a higher number of media outlets did not affect symptoms.

Chemical Anoxia Delays Germ Cell Apoptosis in the Human Testis

Abstract An understanding of testicular physiology and pathology requires knowledge of the regulation of cell death. Previous observation of suppression of apoptosis by hypoxia suggested a role for ATP in germ cell death. However, the exact effects of ATP production on germ cell death and of apoptosis on the levels of ATP and other adenine nucleotides (ANs) have remained unclear. We investigated the levels of ANs during human testicular apoptosis (analyzed by HPLC) and the role of chemical anoxia in germ cell death (detected by Southern blot analysis of DNA fragmentation, in situ end labeling of DNA, and electron microscopy). Incubation of seminiferous tubule segments under serum-free conditions induced apoptosis and concomitantly decreased the levels of ANs. Chemical anoxia, induced with potassium cyanide (KCN), an inhibitor of mitochondrial respiration, dropped ATP levels further and suppressed apoptosis at 4 h. After 24 h, many of the testicular cells underwent delayed apoptosis despite ATP depletion. Some cells showed signs of necrosis or toxicity. The addition of 2-deoxyglucose, an antimetabolite of glycolysis, did not alter the results obtained with KCN alone, whereas a toxic concentration of hydrogen peroxide switched apoptosis to necrosis. In most of the testicular cells, mitochondrial respiration appears to play a crucial role in controlling primary cell death cascades. In the human testis, there seem to be secondary apoptotic pathways that do not require functional respiration (or ATP).

Effects of Acid Sphingomyelinase Deficiency on Male Germ Cell Development and Programmed Cell Death

Abstract Deficiency of acid sphingomyelinase (ASM), an enzyme responsible for producing a pro-apoptotic second messenger ceramide, has previously been shown to promote the survival of fetal mouse oocytes in vivo and to protect oocytes from chemotherapy-induced apoptosis in vitro. Here we investigated the effects of ASM deficiency on testicular germ cell development and on the ability of germ cells to undergo apoptosis. At the age of 20 weeks, ASM knock-out (ASMKO) sperm concentrations were comparable with wild-type (WT) sperm concentrations, whereas sperm motility was seriously affected. ASMKO testes contained significantly elevated levels of sphingomyelin at the age of 8 weeks as detected by high-performance, thin-layer chromatography. Electron microscopy revealed that the testes started to accumulate pathological vesicles in Sertoli cells and in the interstitium at the age of 21 days. Irradiation of WT and ASMKO mice did not elevate intratesticular ceramide levels at 16 h after irradiation. In situ end labeling of apoptotic cells also showed a similar degree of cell death in both groups. After a 21-day recovery period, the numbers of primary spermatocytes and spermatogonia at G2 as well as spermatids were essentially the same in the WT and ASMKO testes, as detected by flow cytometry. In serum-free cultures both ASMKO and WT germ cells showed a significant increase in the level of ceramide, as well as massive apoptosis. In conclusion, ASM is required for maintenance of normal sphingomyelin levels in the testis and for normal sperm motility, but not for testicular ceramide production or for the ability of the germ cells to undergo apoptosis.

The role of attachment in recovery after a school-shooting trauma

Background Survivors of life-endangering trauma use varying resources that help them to recover. Attachment system activates in the times of distress, and is expected to associate with stress responses, arousal regulation, and mental health. Objective We examined the associations of attachment style with posttraumatic stress disorders (PTSD) symptoms and dissociative symptoms, and posttraumatic growth (PTG) among students exposed to a school shooting in Finland in a three-wave follow-up setting. Method Participants were students (M age=24.9 years; 95% female) who were followed 4 (T1, N=236), 16 (T2, N=180), and 28 months (T3, N=137) after the shooting. The assessments included the Attachment Style Questionnaire, the Impact of Event Scale, part of the Adolescent Dissociative Experiences Scale and the Posttraumatic Growth Inventory. Results Securely attached survivors had lower levels of posttraumatic stress and dissociative symptoms than preoccupied at T1 and T2 as hypothesized. At T3 survivors with avoidant attachment style had higher levels of intrusive and hyperarousal symptoms than those with secure style. Concerning PTG, survivors with avoidant attachment style scored lower in PTG at T3 than survivors with both secure and preoccupied style. Conclusion Secure attachment style was beneficial in trauma recovery. A challenge to the health care systems is to acknowledge that survivors with preoccupied and avoidant attachment styles react uniquely to trauma, and thus need help in different doses, modalities, and timings.