R-spondina1 e il suo ruolo nella determinazione e differenziazione sessuale

Sex development comprises a series of sequential events that act under strong genetic control. This complex process is responsible for the achievement of sexual dimorphism and functionality, necessary for reproduction and maintenance of the species. Sex development is the result of the interactions of multiple time and dose-sensitive genes. Although in the last 15 years important scientific progress has been made in our knowledge of the molecular pathways and genes underlying sex development, many factors still remain unknown. Any dysregulation of the mechanisms responsible for sex development may lead to “Disorders of Sex Development” (DSDs), comprising a large group of congenital conditions characterized by “atypical development of chromosomal, gonadal or phenotypic sex”. Due to the complex clinical considerations associated with DSD patients, a precise and well-timed diagnosis is absolutely indispensable. A correct diagnosis is essential to make decisions regarding correct gender assignment and is the basis for appropriate short- and long-term management of DSD patients, to optimise future quality of life. Development of appropriate diagnostic and therapeutic protocols is strongly linked to a deeper understanding of the complex molecular/genetic pathways at the basis of sex development. The purpose of this research has been to improve our understanding of sex development and to provide new insights into the causes of DSDs by studying RSPO1, a new gene we demonstrated to be involved in gonadal development. R-spondin1, a member of a new protein family involved in Wnt/β-catenin pathway, is a gene we discovered to be mutated in a patient with a syndromic form of XX “true hermaphroditism”. The effects of this mutation on mRNA and protein production have been investigated. Moreover, differences between wild-type and mutant protein found in our patient have been evaluated, by investigating RSPO1 cellular expression, localization and secretion. To clarify the mechanism of action of RSPO1, functional analysis has been performed using luciferase assays. Preliminary data about identification of RSPO1 target pathways and genes have been achieved by overexpression and microarray approaches. The work of this thesis has led to further elucidate the role of R-spondin1 in gonadal determination and to expand the spectrum of DSD phenotypes related to RSPO1 mutations. Our studies to define the role of R-spondin1 might lead to the development of new tools in the diagnosis and treatment of DSD pathologies.