In Vivo and in Vitro Structure-Activity Relationships and Structural Conformation of Kisspeptin-10-Related Peptides

International audienceKisspeptins, the natural ligands of the G protein-coupled receptor KISS1R, comprise a family of related peptides derived from the proteolytic processing of a common precursor encoded by the KISS1 gene. Among those, Kisspeptin-10 (Kp-10) contains the basic residues to retain full functional activity and exhibits higher receptor affinity and biopotency than longer forms of the peptide. Although kisspeptins were first characterized by their ability to inhibit tumor metastasis, recent studies have revealed that the KISS1/KISS1R system plays an essential role in the neuroendocrine control of the reproductive axis. In this context, development and functional analysis of Kp-10 analogs may help in the search for new agonists and antagonists as valuable tools to manipulate the KISS1/KISS1R system and hence fertility. We report herein functional and structural analyses of a series of Ala-substituted rat kp-10 analogs, involving [Ca(2+)](i) responses in rat kiss1r-transfected Chinese hamster ovary cells, dynamic luteinizing hormone (LH) responses in vivo, and NMR structural studies. In vitro assays revealed that Ala substitutions in positions 6 or 10 of kp-10 resulted in a significant increase in EC(50) values (>6.46 x 10(-6) M versus 1.54 to 2.6 x 10(-8) M for rat and human Kp-10, respectively) and a substantial decrease in the proportion of responsive cells coupled to a marked increase in the time required to reach maximal response. In vivo assays showed that Ala(6) substitution diminished and Ala(10) substitution eliminated LH secretory responses, whereas coadministration of each analog failed to affect the LH-releasing ability of kp-10. Molecular modeling under NMR restraints revealed that kp-10 exhibits a helicoidal structure between the Asn(4) and Tyr(10) residues, with mixed alpha- and 3(10)-helix characteristics. Ala(6) substitution induced limited destabilization of the helix around the position of the substitution. Ala(10) substitution was found to totally disrupt the helical structure in the C-terminal region of the molecule. Taken together, our results indicate that positions 6 and 10 are critical for kp-10 action at kiss1r and suggest that modifications in these positions could lead to the generation of new kisspeptin agonists and/or antagonists with altered functional and perhaps binding properties. Furthermore, they emphasize the importance of using combined, multidisciplinary approaches, including in vivo studies, to reliably evaluate structure function properties of novel kisspeptin analogs

Toxic-Metabolite-Producing Bacteria and Fungus in an Indoor Environment

Toxic-metabolite-emitting microbes were isolated from the indoor environment of a building where the occupant was suffering serious building-related ill-health symptoms. Toxic substances soluble in methanol and inhibitory to spermatozoa at <10 μg (dry weight) ml(−1) were found from six bacterial isolates and one fungus. The substances from isolates of Bacillus simplex and from isolates belonging to the actinobacterial genera Streptomyces and Nocardiopsis were mitochondriotoxic. These substances dissipated the mitochondrial membrane potential (Δψ) of boar spermatozoa. The substances from the Streptomyces isolates also swelled the mitochondria. The substances from isolates of Trichoderma harzianum Rifai and Bacillus pumilus damaged the cell membrane barrier function of sperm cells

Ecological footprinting as a top-down and bottom-up approach to complete campus engagement and transformation towards the One Planet Goal

Enabling students to apply well-informed and skill-based understandings to their own decision-making about the dynamic relationships between individuals, societies, environments and economies in a resource constrained world is a central sustainability goal in the tertiary sector. Ecological Footprinting (EF) measures how much people have, how much they use and identifies who uses what. At Macquarie University, in Sydney Australia, EF has been applied at the campus, faculty and building scales and integrated into student learning through the undergraduate Environmental Management curriculum, where students consider their own footprints (personal and household) and investigate EF at the faculty scale. At the building scale, the University's Property Department calculates the EF of individual buildings (new and existing) to ensure as the University grows, it reaches a One Planet campus target by 2030. The students' research projects utilise the Property Department's EF tool. This has generated a cross-campus partnership across academic-non-academic, disciplinary and department structures towards institutional goals. This integrated, top-down and bottom-up approach fosters transformative engagement across the entire campus. This paper presents the strategic and methodological approach of the integrated sustainability strategy, reviews early stage results and next steps towards a One Planet campus and society.24 page(s

A comprehensive model of predictors of quality of life in older adults with schizophrenia: results from the CSA study

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Effects of depression and cognitive impairment on quality of life in older adults with schizophrenia spectrum disorder: Results from a multicenter study

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