PLXNB1 is a protein of the hepatic growth factor receptor family and the reecptor for the transmembrane semaphorin SEMA4D, also called
CD100 (OMIM 601866).
NCBI Summary:
Plexin 5; involved in mediating cell guidance; member of the plexin family of semaphorin receptors
General function
Receptor
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Cellular localization
Plasma membrane
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Ovarian function
Steroid metabolism
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Expression regulated by
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Ovarian localization
Oocyte, Granulosa
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Taft RA, et al 2002 reported the identification of genes encoding mouse oocyte secretory and
transmembrane proteins by a signal sequence trap.
At all stages of follicular
development, oocytes interact with surrounding granulosa cells and promote their
differentiation into the types of cells that support further oocyte growth and
developmental competence. These interactions suggest the existence of an
oocyte-granulosa cell regulatory loop that includes both secreted proteins and cell
surface receptors on both cell types. Factors involved in the regulatory loop will
therefore contain a signal sequence, which can be used to identify them through a
signal sequence trap (SST). A screen of an oocyte SST library identified three
classes of oocyte-expressed sequences: known mouse genes, sequences homologous
to known mammalian genes, and novel sequences of unknown function. Many of the
recovered genes may have roles in the oocyte-granulosa cell regulatory loop. For
several of the known mouse genes, new roles in follicular development are implied
by identification of their expression, for the first time, in the oocyte.
Plexin B1 was found by the SST screen.
Follicle stages
Antral
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Expression of plexin-B1 in the mouse ovary and its possible role in follicular development Regev A, et al .
OBJECTIVE: To study the expression of plexin-B1 in the mouse ovary and its possible role in follicular development. DESIGN: Controlled laboratory study. SETTING: Research laboratory, Ha'Emek Medical Center. PATIENT(S): ICR female mice (n = 36) were studied. MAIN OUTCOME MEASURE(S): Plexin-B1 expression by immunohistochemistry, Western blot analysis, and reverse transcriptase-polymerase chain reaction. Microscopic morphometric and morphologic analysis for the evaluation of mouse follicular growth and E2, P, and T secretion from the developed follicles. RESULT(S): Plexin-B1 was expressed in the mouse ovary mostly in the granulosa cells. Plexin-B1 gene expression increased significantly by 126.8% +/- 38% in the pregnant mare serum gonadotropin-treated group and increased by 98.7% +/- 15.2 and 262.2% +/- 65.4% in the hCG-treated group 6 h and 24 h after injection, respectively (ANOVA; P < .05). Comparison of the maximum diameters of the control and study groups on day 9 of the culture period revealed a significant difference between the two groups (P < .001). In the control group, the mean maximum diameter was 191 +/- 2.6 microm compared with 136 +/- 5.13 microm in the presence of neutralizing antibodies against plexin-B1. Neutralizing antibody against plexin-B1 decreases E2 and P secretion. CONCLUSION(S): This study shows for the first time the expression of plexin-B1 in the mouse ovary. A possible role for plexin-B1 in follicular growth and steroidogenesis, most likely via the granulosa cells, is suggested.