Differential regulation of kit ligand A (kitlga) expression in the zebrafish ovarian follicle cells--evidence for the existence of a cyclic adenosine 3', 5' monophosphate-mediated binary regulatory system during folliculogenesis

Therapeutic modulation of KIT ligand in melanocytic disorders with implications for mast cell diseases

KIT ligand and its associated receptor KIT serve as a master regulatory system for both melanocytes and mast cells controlling survival, migration, proliferation and activation. Blockade of this pathway results in cell depletion, while overactivation leads to mastocytosis or melanoma. Expression defects are associated with pigmentary and mast cell disorders. KIT ligand regulation is complex but efficient targeting of this system would be of significant benefit to those suffering from melanocytic or mast cell disorders. Herein, we review the known associations of this pathway with cutaneous diseases and the regulators of this system both in skin and in the more well-studied germ cell system. Exogenous agents modulating this pathway will also be presented. Ultimately, we will review potential therapeutic opportunities to help our patients with melanocytic and mast cell disease processes potentially including vitiligo, hair greying, melasma, urticaria, mastocytosis and melanoma.

cAMP signaling in ovarian physiology in teleosts: A review

Ovarian function in teleosts, like in other vertebrates, is regulated by two distinct gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Gonadotropin effects are mediated by membrane-bound G protein-coupled receptors localized on the surface of follicle cells. Gonadotropin receptor activation results in increased intracellular cAMP, the most important second cellular signaling molecule. FSH stimulation induces the production of 17β-estradiol in the cells of growing follicles to promote vitellogenesis in oocytes. In contrast, in response to LH, fully grown post-vitellogenic follicles gain the ability to synthesize maturation-inducing steroids, which induce meiotic resumption and ovulation. All these events were induced downstream of cAMP. In this review, we summarize studies addressing the role of the cAMP pathway in gonadotropin-induced processes in teleost ovarian follicles. Furthermore, we discuss future problems concerning cAMP signaling in relation to teleost ovarian function and the differences and similarities in the gonadotropin-induced cAMP signaling pathways between mammals and teleosts.

Zebrafish Nedd8 facilitates ovarian development and the maintenance of female secondary sexual characteristics via suppression of androgen receptor activity

Nedd8 is a ubiquitin-like protein that covalently conjugates to target proteins through neddylation. In addition to cullin-RING ligases, neddylation also modifies non-cullin proteins to regulate protein activity, stability and localization. However, the roles of NEDD8 remain largely unknown in vivo Here, we found that loss of nedd8 in female zebrafish led to defects in oogenesis, disrupted oocyte maturation and stimulated growth of the breeding tubercles (BTs) on the pectoral fins. The BTs are normally present in males, not females. However, the loss of one copy of ar can partially rescue the phenotypes displayed by nedd8-null female zebrafish. Further assays indicated that Nedd8 conjugates to Ar and Ar is neddylated at lysine 475 and lysine 862. Moreover, Nedd8 conjugation efficiently suppressed Ar transcriptional activity. Lysine 862 (K862) of Ar is the key site modified by neddylation to modulate Ar transcriptional activity. Thus, our results not only demonstrated that Nedd8 modulates ovarian maturation and the maintenance of female secondary sexual characteristics of female zebrafish in vivo, but also indicated that androgen signaling is strictly regulated by nedd8.

Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development

This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.

THE GENETICS OF EPIGENETIC INHERITANCE: MODES, MOLECULES, AND MECHANISMS

Organisms adapt developmental and physiological features to local and transient conditions in part by modulating transcription, translation, and protein functions, usually without changing DNA sequences. Remarkably, these epigenetic changes sometimes endure through meiosis and gametogenesis, thereby affecting phenotypic variation across generations, long after epigenetic changes were triggered. Transgenerational effects challenge our traditional understanding of inheritance. In this review, we focus on patterns of inheritance, molecular features, mechanisms that lead from environmental and genetic perturbations to phenotypic variation in later generations, and issues about study design and replication.