No abstract

Changes that occur to mammalian sperm upon epididymal transit and maturation render these cells capable of moving progressively and capacitating. Signaling events leading to mammalian sperm capacitation depend on the modulation of proteins by phosphorylation and dephosphorylation cascades. Recent experiments have demonstrated that the Src family of kinases plays an important role in the regulation of these events. However, sperm from cSrc null mice display normal tyrosine phosphorylation associated with capacitation. We report here that, despite normal phosphorylation, sperm from cSrc null mice display a severe reduction in forward motility, and are unable to fertilize in vitro. Histological analysis of seminiferous tubules in the testes, caput and corpus epididymis do not reveal obvious defects. However, the cauda epididymis is significantly smaller, and expression of key transport proteins in the epithelial cells lining this region is reduced in cSrc null mice compared to wild type littermates. Although previously, we and others have shown the presence of cSrc in mature sperm from cauda epididymis, a closer evaluation indicates that this tyrosine kinase is not present in sperm from the caput epididymis, suggesting that this protein is acquired by sperm later during epididymal maturation. Consistent with this observation, cSrc is enriched in vesicles released by the epididymal epithelium known as epididymosomes. Altogether, these observations indicate that cSrc is essential for cauda epididymal development and suggest an essential role of this kinase in epididymal sperm maturation involving cSrc extracellular trafficking.

The multifaceted polycomb group gene Yin-Yang1 (Yy1) has been implicated in a variety of transcriptional regulatory roles both as an activator and silencer of gene expression. Here we examine the role of Yy1 during oocyte growth by conditional deletion of the locus in the growing oocyte. Our results indicate that YY1 is required for oocyte maturation and granulosa cell expansion. In mutant oocytes, we observe severely reduced expression of both Gdf9 and Bmp15, suggesting a mechanism underlying the failure of granulosa cell expansion. Consequently, we observe infertility, failure of estrus cycling, and altered reproductive hormone levels in mutant females. Additionally, we find that YY1-deficient oocytes exhibit altered levels of several oocyte-specific factors, including Pou5f1, Figla, Lhx8, Oosp1, and Sohlh2. These results document YY1's involvement in folliculogenesis and ovarian function in the mouse and indicate that YY1 is required specifically in the oocyte for oocyte-granulosa cell communication.

Background: The adherens protein VE-cadherin has diverse roles in organ-specific lymphatic vessels. However, its physiological role in cardiac lymphatics and its interaction with lymphangiogenic factors, has not been fully explored. We sought to determine the spatio-temporal functions of VE-cadherin in cardiac lymphatics and mechanistically elucidate how VE-cadherin loss influences pro-lymphangiogenic signaling pathways, such as adrenomedullin (AM) and VEGF-C/VEGFR3 signaling. Methods: Cdh5 flox/flox ;Prox1CreER T2 mice were used to delete VE-cadherin in lymphatic endothelial cells (LECs) across life stages, including embryonic, postnatal and adult. Lymphatic architecture and function was characterized utilizing immunostaining and functional lymphangiography. To evaluate the impact of temporal and functional regression of cardiac lymphatics in Cdh5 flox/flox ;Prox1CreER T2 mice, left anterior descending artery ligation was performed and cardiac function and repair after myocardial infarction was evaluated by echocardiography and histology. Cellular effects of VE-cadherin deletion on lymphatic signaling pathways were assessed by knock-down of VE-cadherin in cultured LECs. Results: Embryonic deletion of VE-cadherin produced edematous embryos with dilated cardiac lymphatics with significantly altered vessel tip morphology. Postnatal deletion of VE-cadherin caused complete disassembly of cardiac lymphatics. Adult deletion caused a temporal regression of the quiescent epicardial lymphatic network which correlated with significant dermal and cardiac lymphatic dysfunction, as measured by fluorescent and quantum dot lymphangiography, respectively. Surprisingly, despite regression of cardiac lymphatics, Cdh5 flox/flox ;Prox1CreER T2 mice exhibited preserved cardiac function, both at baseline and following myocardial infarction, compared to control mice. Mechanistically, loss of VE-cadherin leads to aberrant cellular internalization of VEGFR3, precluding the ability of VEGFR3 to be either canonically activated by VEGF-C or non-canonically transactivated by AM signaling, impairing downstream processes such as cellular proliferation. Conclusions: VE-cadherin is an essential scaffolding protein to maintain pro-lymphangiogenic signaling nodes at the plasma membrane, which are required for the development and adult maintenance of cardiac lymphatics, but not for cardiac function basally or after injury.

No abstract

Electronic nicotine delivery system (e-cigarette) use is prevalent among pregnant women as a seemingly safe alternative to traditional tobacco use, known to result in fetal developmental abnormalities and impaired fertility of male offspring. However, little is known about the effects of e-cigarette use on fertility or pregnancy outcomes. A successful pregnancy is initiated by a multitude of dynamic molecular alterations in the uterus resulting in embryo implantation at day 4.5 in the mouse. We examined whether e-cigarette exposure impairs implantation and offspring health. Pregnant C57BL/6J mice were exposed five times a week to e-cigarette vapor or sham. After 4 months, e-cigarette exposed dams exhibited a significant delay in the onset of the first litter. Furthermore, exposure of new dams in early pregnancy significantly impaired embryo implantation, as evidenced by nearly complete absence of implantation sites in e-cigarette–exposed animals at day 5.5, despite exhibiting high levels of progesterone, an indicator of pregnancy. RNA microarray from day 4.5 pseudopregnant mice revealed significant changes in the integrin, chemokine, and JAK signaling pathways. Moreover, female offspring exposed to e-cigarettes in utero exhibited a significant weight reduction at 8.5 months, whereas males exhibited a slight but nonsignificant deficiency in fertility. Thus, e-cigarette exposure in mice impairs pregnancy initiation and fetal health, suggesting that e-cigarette use by reproductive-aged women or during pregnancy should be considered with caution.

Transforming growth factor‐β (TGF‐β) superfamily signaling via their cognate receptors is frequently modified by TGF‐β superfamily co‐receptors. Signaling through SMAD‐mediated pathways may be enhanced or depressed depending on the specific co‐receptor and cell context. This dynamic effect on signaling is further modified by the release of many of the co‐receptors from the membrane to generate soluble forms that are often antagonistic to the membrane‐bound receptors. The co‐receptors discussed here include TβRIII (betaglycan), endoglin, BAMBI, CD109, SCUBE proteins, neuropilins, Cripto‐1, MuSK, and RGMs. Dysregulation of these co‐receptors can lead to altered TGF‐β superfamily signaling that contributes to the pathophysiology of many cancers through regulation of growth, metastatic potential, and the tumor microenvironment. Here we describe the role of several TGF‐β superfamily co‐receptors on TGF‐β superfamily signaling and the impact on cellular and physiological functions with a particular focus on cancer, including a discussion on recent pharmacological advances and potential clinical applications targeting these co‐receptors.

Gastric inhibitory polypeptide (GIP) receptor is a class B1 GPCR, that responds to GIP and physiologically potentiates glucose-stimulated insulin secretion. Like most class B1 GPCRs, GIPR has been shown to interact with RAMPs, yet the effects of RAMPs on its signalling and trafficking remain poorly understood. We demonstrate that RAMPs modulate G protein activation and GIPR internalisation profiles. RAMP3 reduced GIPR Gs activation and cAMP production but retained GIPR at the cell surface, and this was associated with prolonged ERK1/2 phosphorylation and β-arrestin association. By contrast, RAMP1/2 reduced Gq/11/15 activation of the GIPR. Through knockout mice studies, we show that RAMP1 is important to the normal physiological functioning of GIPR to regulate blood glucose levels. Thus, RAMPs act on G protein/β-arrestin complexes, having both acute and chronic effects on GIPR function, while this study also raises the possibility of a more general role of RAMP3 to enhance GPCR plasma membrane localisation.