The KISSPEPTIN-1 receptor (KISS1R) and its ligands (KISSPEPTINS) are implicated in the regulation of the onset of puberty. We report the coding region and genomic structure of the kiss1r gene of a modern teleost, the Senegalese sole (Ss). Ss kiss1r cDNA contained an opening frame of 1137 bp, which results in a predicted 378 amino acid protein. Searching genomic databases allowed the identification of kiss1r orthologues in six new species belonging to three vertebrate groups and established the evolutionary relationships of all KISS1R sequences available to date. Analysis of Ss kiss1r revealed for the first time in any vertebrate KISS1R gene the presence of features that are characteristic of a mechanism of alternative splicing. This was confirmed by the identification of two transcripts, Ss kiss1r_v1 and Ss kiss1r_v2. The latter, arising from intron III retention, contained a 27 codons insert in transmembrane region 4 with two stop codons, suggesting it may lead to a truncated protein. The mRNA of the two variants was differently expressed in several tissues. In the brain, levels of the Ss kiss1r_v1 were higher than those of Ss kiss1r_v2. In the gonads, the opposite was observed. Both isoforms exhibited changes depending on sex and maturity stage. The presence of two variants may help to explain some discrepancies observed in past studies regarding KISS1R expression during puberty. Thus, the existence of alternative splicing for the KISS1R gene may contribute to our understanding of the many physiological functions suspected to be mediated by KISSPEPTIN-KISS1R signaling.

Kisspeptin signaling in the brain is involved in the control of the onset of puberty in vertebrates. In this study, we present novel evidence indicating that kisspeptin may link energy balance and reproduction. For that purpose, we determined the complete gene structure of kisspeptin in a teleost fish, the Senegalese sole (Ss). In contrast to the situation evident in several fish, in this species only Kiss2 was found. Yet, two Ss Kiss2 isoforms generated by alternative splicing through intronic retention were detected: Ss Kiss2_v1, producing the functional protein, and Ss Kiss2_v2, coding for a truncated, non-functional protein. Specific qPCRs showed that the expression of these two isoforms varied differently in brain and gonads throughout maturation. In addition, and in contrast to what has been observed in mammals, fasting increased hypothalamic mRNA levels of Ss Kiss2_v1, which also caused a concomitant rise in pituitary Ss LH and Ss FSH mRNA. Together, these data indicate the impact of the nutritional status on Kiss mRNA expression as a potential regulatory mechanism for the metabolic control of reproduction in non-mammalian species, albeit with some significant differences with respect to the situation described in mammals.

No abstract

No abstract

No abstract

In vertebrates, kisspeptins and their receptors are known to be related to puberty onset and gonadal maturation, however, there are few studies concerning their role in early development. Here, we characterize the kisspeptin system in the pejerrey, Odontesthes bonariensis, a fish with strong temperature-dependent sex determination. We reconstructed the phylogenetic history of the two ligands (kiss1 and kiss 2) and two receptors (kissr2 and kissr3) in pejerrey in the context of recent classifications of bony fishes, determined their tissue distribution and documented the early expression pattern of these ligands and receptors. Phylogenetic analysis of these gene families clearly resolved the percomorph clade and grouped pejerrey with Beloniformes. Paralogous sets of genes putatively arising from the teleost-specific genome duplication event (3R) were not detected. Kisspeptins and their receptors showed a wide tissue distribution in adult pejerrey, including tissues not related to reproduction. In larvae reared at 24°C, the four kisspeptin elements were expressed in the head from week 1 to week 8 of life, with no differences in transcript levels. Larvae kept at a female-producing temperature (17°C) did not show statistically significant differences in the transcript levels of all analyzed genes during the sex determination/differentiation period; however, in those larvae raised at male producing temperature (29°C), kiss2 levels were increased at week 4 after hatching. These results showed that all members of the kisspeptin system are expressed at this early period, and the increase of kiss2 transcripts at week 4 could be interpreted as it would be related to the differentiation of the brain-pituitary axis in male development.

No abstract

Protein-coding mutations in the transcription factor-encoding gene ARX cause various forms of intellectual disability (ID) and epilepsy. In contrast, variations in surrounding non-coding sequences are correlated with milder forms of non-syndromic ID and autism and had suggested the importance of ARX gene regulation in the etiology of these disorders. We compile data on several novel and some already identified patients with or without ID that carry duplications of ARX genomic region and consider likely genetic mechanisms underlying the neurodevelopmental defects. We establish the long-range regulatory domain of ARX and identify its brain region-specific autoregulation. We conclude that neurodevelopmental disturbances in the patients may not simply arise from increased dosage due to ARX duplication. This is further exemplified by a small duplication involving a non-functional ARX copy, but with duplicated enhancers. ARX enhancers are located within a 504-kb region and regulate expression specifically in the forebrain in developing and adult zebrafish. Transgenic enhancer-reporter lines were used as in vivo tools to delineate a brain region-specific negative and positive autoregulation of ARX. We find autorepression of ARX in the telencephalon and autoactivation in the ventral thalamus. Fluorescently labeled brain regions in the transgenic lines facilitated the identification of neuronal outgrowth and pathfinding disturbances in the ventral thalamus and telencephalon that occur when arxa dosage is diminished. In summary, we have established a model for how breakpoints in long-range gene regulation alter the expression levels of a target gene brain region-specifically, and how this can cause subtle neuronal phenotypes relating to the etiology of associated neuropsychiatric disease.