Sperm banking before gonadotoxic treatment: is it worth the effort?

We aimed to compare the sperm quality in different cancer types and benign diseases before gonadotoxic treatment, and assess the usage rate of cryopreserved sperm for assisted reproductive treatment (ART). This retrospective study was conducted at two university clinics between January 2008 and July 2018. A total of 545 patients suffering from cancer or benign diseases were included in the study. The pretreatment sperm analyses were based on the World Health Organization (WHO) guidelines. Patients with testicular malignancy (TM) showed a significantly lower sperm count (median [interquartile range]: 18.7 × 106 [5.3 × 106-43.0 × 106] ml-1; P = 0.03) as well as total sperm count (42.4 × 106 [13.3 × 106-108.5 × 106] per ejaculate; P = 0.007) compared to other malignant and benign diseases. In addition, patients with nonseminomatous TM showed the lowest sperm count (14.3 × 106 [6.0 × 106-29.9 × 106] ml-1, vs seminomas: 16.5 × 106 [4.6 × 106-20.3 × 106] ml-1; P = 0.001). With reference to the WHO 2010 guidelines, approximately 48.0% of the patients with TM and 23.0% with hematological malignancies (HM) had oligozoospermia. During the observation period, only 29 patients (5.3%) used their frozen sperms for 48 ART cycles, resulting in 15 clinical pregnancies and 10 live births. The sperm quality varies with the type of underlying disease, with TM and HM patients showing the lowest sperm counts. Due to the observed low usage rate of cryopreserved sperm, further patient interviews and sperm analyses should be included in the routine oncologic protocols to avoid unnecessary storage expenses. However, sperm banking is worth the effort as it provides hope for men who cannot reproduce naturally after gonadotoxic treatment.

Regulation of the delta and alpha epithelial sodium channel (ENaC) by ubiquitination and Nedd8.

The δ epithelial sodium channel (δENaC) is a proton-activated, sodium-selective, amiloride-sensitive ion channel in the ENaC/degenerin family of ion channels involved in blood pressure regulation and mechanosensation. Other ENaC family members are subject to ubiquitin modification leading to internalization from the cell surface, and degradation of the channel. Here, we show that δENaC is also modified by ubiquitin on three intracellular lysine residues. Absence of these lysines abolished ubiquitin modification of δENaC and increased cell surface levels of δENaC. Although the HECT-domain ubiquitin ligase Nedd4-2 reduced amiloride-sensitive current generated by δßγENaC-containing channels, δENaC does not contain a binding site for Nedd4-2; therefore, this effect is probably mediated by the ßγENaC subunits. Nedd8, a ubiquitin-like protein that regulates RING-domain E3 ubiquitin ligases, promoted δENaC ubiquitination, decreased both the intracellular and cell surface δENaC populations, and decreased δßγENaC amiloride-sensitive short circuit current (Isc -amiloride) in a mammalian epithelium. Nedd8 also promoted α- and γENaC ubiquitination, decreased the cell surface pools, and decreased αßγENaC Isc -amiloride. Conversely, XIAP, a single subunit RING E3 ligase, decreased ubiquitinated δENaC, increased the δENaC cell surface pool and increased δßγENaC Isc -amiloride. Therefore δ- and α - ßγENaC channel function may be influenced by RING-domain E3 ubiquitin ligases.

Genetic evidence for involvement of neuronally expressed S1P1 receptor in nociceptor sensitization and inflammatory pain.

Sphingosine-1-phosphate (S1P) is a key regulator of immune response. Immune cells, epithelia and blood cells generate high levels of S1P in inflamed tissue. However, it is not known if S1P acts on the endings of nociceptive neurons, thereby contributing to the generation of inflammatory pain. We found that the S1P1 receptor for S1P is expressed in subpopulations of sensory neurons including nociceptors. Both S1P and agonists at the S1P1 receptor induced hypersensitivity to noxious thermal stimulation in vitro and in vivo. S1P-induced hypersensitivity was strongly attenuated in mice lacking TRPV1 channels. S1P and inflammation-induced hypersensitivity was significantly reduced in mice with a conditional nociceptor-specific deletion of the S1P1 receptor. Our data show that neuronally expressed S1P1 receptors play a significant role in regulating nociceptor function and that S1P/S1P1 signaling may be a key player in the onset of thermal hypersensitivity and hyperalgesia associated with inflammation.

Identification of Murr1 as a regulator of the human delta epithelial sodium channel.

The human delta epithelial sodium channel (deltaENaC) subunit is related to the alpha-, beta-, and gammaENaC subunits that control salt homeostasis. DeltaENaC forms an amiloride-sensitive Na+ channel with the beta and gamma subunits. However, the in vivo function of deltaENaC is not known. To gain insight into the function of deltaENaC, a yeast two-hybrid screen of a human brain cDNA library was carried out using the C- and N-terminal domains of deltaENaC. A novel deltaENaC-interacting protein called Murr1 (mouse U2af1-rs1 region) was isolated in the C-terminal domain screen. Murr1 is a 21-kDa protein mutated in Bedlington terriers suffering from copper toxicosis. The interaction of Murr1 and deltaENaC was confirmed by glutathione S-transferase pulldown assay and coimmunoprecipitation. To test the functional significance of the interaction, Murr1 was coexpressed with deltabetagammaENaC in Xenopus oocytes. Murr1 inhibited amiloride-sensitive sodium current in a dose-dependent manner. In addition, deletion of the last 59 amino acids of deltaENaC abolished the inhibition. Murr1 also bound to the beta- and gammaENaC subunits and inhibited alphabetagammaENaC sodium current. Therefore, these results suggest that Murr1 is a novel regulator of ENaC.