NCBI Summary:
The protein encoded by this gene belongs to the ROBO family, part of the immunoglobulin superfamily of proteins that are highly conserved from fly to human. The encoded protein is a transmembrane receptor for the slit homolog 2 protein and functions in axon guidance and cell migration. Mutations in this gene are associated with vesicoureteral reflux, characterized by the backward flow of urine from the bladder into the ureters or the kidney. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2014]
General function
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Cellular localization
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Ovarian function
Follicle atresia, Luteolysis
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Expression regulated by
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Ovarian localization
Oocyte, Granulosa, Luteal cells
Comment
Novel regulated expression of the SLIT/ROBO pathway in the ovary: possible role during luteolysis in women. Dickinson RE et al. The human corpus luteum (CL) undergoes luteolysis, associated with marked tissue and vascular remodeling, unless conception occurs and the gland is 'rescued' by human chorionic gonadotropin (hCG). In Drosophila the Slit gene product, a secreted glycoprotein, acts as a ligand for the roundabout (robo) transmembrane receptor. Together they influence the guidance and migration of neuronal and non-neuronal cells. In vertebrates three Slit (Slit1, Slit2, Slit3) and four Robo (Robo1, Robo2, Robo3/Rig-1, Robo4/Magic Robo) genes have been identified. ROBO1, SLIT2 and SLIT3 are also inactivated in human cancers and may regulate apoptosis and metastasis. Since processes such as apoptosis and tissue remodeling occur during the regression of the CL, the aim of this study was to investigate the expression, regulation and effects of the SLIT and ROBO genes in human luteal cells. Immunohistochemistry and RT-PCR revealed that SLIT2, SLIT3, ROBO1 and ROBO2 are expressed in luteal steroidogenic cells and fibroblast-like cells of the human CL. Furthermore, using real-time quantitative PCR, expression of SLIT2, SLIT3, and ROBO2 was maximal in the late-luteal phase and significantly reduced after luteal 'rescue' in vivo with exogenous hCG (P<0.05). Additionally, hCG significantly inhibited SLIT2, SLIT3 and ROBO2 expression in cultured luteinized granulosa cells (P<0.05). Blocking SLIT-ROBO activity increased migration and significantly decreased levels of apoptosis in primary cultures of luteal cells (P<0.05). Overall these results suggest the SLIT/ROBO pathway could play an important role in luteolysis in women.
Follicle stages
Comment
Involvement of the SLIT/ROBO pathway in follicle development in the fetal ovary. Dickinson RE et al. In humans and domestic mammals pivotal processes in ovary development, including primordial follicle assembly, occur prenatally. These events are essential for determining fertility in adult life however they remain poorly understood at the mechanistic level. In mammals the SLITs (SLIT1, SLIT2, SLIT3) and their ROBO (ROBO1, ROBO2, ROBO3/RIG-1, ROBO4/MAGIC ROBO) receptors regulate neural, leukocyte, vascular smooth muscle cell and endothelial cell migration. In addition the SLIT/ROBO pathway has functional roles in embryonic development and in the adult ovary by inhibiting cell migration and promoting apoptosis. We therefore characterised follicle formation and investigated the expression and localisation of the ROBO/SLIT pathway in the ovine fetal ovary. Using RT-PCR, we identified SLIT2, SLIT3, ROBO1, ROBO2 and ROBO4 in sheep ovaries harvested across gestation. The real-time quantitative PCR results implied that ROBO2 and ROBO4 expression were elevated during the early stages of follicle formation and stayed abundant during primordial follicle maturation (P<0.05). Immunohistochemistry examination demonstrated that ROBO1 was localised to the pre-granulosa cells while ROBO2, ROBO4 and SLIT2 were expressed in the oocytes of the developing primordial follicle. This indicates that in the fetal ovary SLIT-ROBO signalling may require an autocrine and paracrine interaction. Furthermore at the time of increased SLIT-ROBO expression there was a significant reduction in the number of proliferating oocytes in the developing ovary (P<0.0001). Overall these results suggest, for the first time, that the SLIT-ROBO pathway is expressed at the time of follicle formation during fetal ovary development.
Phenotypes
Mutations
1 mutations
Species: mouse
Mutation name: type: null mutation fertility: fertile Comment: Robo1/2 regulate follicle atresia through manipulating granulosa cell apoptosis in mice. Li J et al. (2015) Secreted Slit proteins and their Roundabout (Robo) receptors act as a repulsive cue to preventaxons from migrating to inappropriate locations during the development of the nervous system. Slit/Robo has also been implicated in reproductive system development, but the molecular mechanism of the Slit/Robo pathway in the reproductive system remains poorly understood. Using a transgenic mouse model, we investigated the function of the Slit/Robo pathway on ovarian follicle development and atresia. We first demonstrated that more offspring were born to mice with a partial knockout of the Robo1/2 genes in mice. We next showed that Robo1 and Robo2 are strongly expressed in ovarian granulosacells. Apoptosis in granulosa cells was reduced when Robo1/2 were partially knocked out, and this observation was further verified by in vitro Robo1/2 knockout experiments in mouse and human granulosa cells. We also found that ovarian angiogenesis wasenhanced by a partial lack of Robo1/2 genes. In summary, our data suggest that the Slit/Robo pathway can impact follicle development and atresia by influencinggranulosa cell apoptosis.//////////////////