To determine the influence of FSH receptor variants Thr307-Asn680 (TN) and Ala307-Ser680 (AS) on ovarian function, we investigated the frequency of these gene polymorphisms by using restriction fragment length polymorphism analysis and observed their effects on clinical manifestations. In a population of 522 Japanese women, the overall frequency of TN/TN (NN), TN/AS (NS), and AS/AS (SS) was 41.0, 46.9 and 12.1% respectively. In polycystic ovary patients, the NS population was significantly larger when compared with the spontaneously ovulating group (66.7 versus 43.5%, P < 0.05). In the SS group, a significantly higher (46%) basal level of serum FSH was observed as compared with that in the NS group (P < 0.05). A higher dose of the exogenous gonadotrophin was required to achieve ovulation induction in the SS group as compared with the NS group (P < 0.05). At the time of hCG administration, estradiol levels per oocyte retrieved for IVF in the SS group were significantly lower as compared with the levels in the NS and NN groups (P < 0.05). There were no significant differences in FSH-stimulated cAMP production and PI turnover as well as ligand-binding affinity between the two receptor isoforms when overexpressed in transfected 293T cells. These results suggest that although FSH receptor polymorphisms have no discernible effect on FSH receptor function in vitro, there are associations between the genotype and some aspects of patient status.

Cell-mediated autoimmunity has been strongly implicated in the pathogenesis of vascular cell injury in Takayasu's arteritis. To clarify the immunological mechanisms involved, we examined the expression of a cytolytic factor, perforin in infiltrating cells of aortic tissue samples from seven patients with Takayasu's arteritis. We also examined the expression of a 65-kD heat-shock protein

Myosin X is involved in the reorganization of the actin cytoskeleton and protrusion of filopodia. Here we studied the molecular mechanism by which bovine myosin X is regulated. The globular tail domain inhibited the motor activity of myosin X in a Ca(2+)-independent manner. Structural analysis revealed that myosin X is monomeric and that the band 4.1-ezrin-radixin-moesin (FERM) and pleckstrin homology (PH) domains bind to the head intramolecularly, forming an inhibited conformation. Binding of phosphatidylinositol-3,4,5-triphosphate (PtdIns(3,4,5)P(3)) to the PH domain reversed the tail-induced inhibition and induced the formation of myosin X dimers. Consistently, disruption of the binding of PtdIns(3,4,5)P(3) attenuated the translocation of myosin X to filopodial tips in cells. We propose the following mechanism: first, the tail inhibits the motor activity of myosin X by intramolecular head-tail interactions to form the folded conformation; second, phospholipid binding reverses the inhibition and disrupts the folded conformation, which induces dimer formation, thereby activating the mechanical and cargo transporter activity of myosin X.

Compartmentalized signaling involving cholesterol-rich, liquid-ordered membrane domains occurs during cell activation triggered by receptor cross-linking, growth factors, or other extracellular stimuli (1-3). The redistribution of similar liquidordered domains, called lipid ''rafts,'' accompanies and is required for cell polarization and directed migration (4 -8). Although we do not know the precise molecular mechanisms by which the redistributions of plasma membrane domains occur, an active role of the actin-based membrane skeleton has long been postulated (reviewed in Ref. 9).Redistributions of activated or cross-linked receptors are accompanied by corresponding changes in the localizations of actin, nonmuscle myosin II, spectrin, and associated cytoskeletal proteins (9). Furthermore, disruption of actin filament integrity inhibits many lipid raft-mediated processes, including epidermal growth factor receptor capping in A431 cells (10), insulin receptor capping in lymphocytes (11), activation of fibroblasts (12), polarization of T lymphocytes (5), and downregulation of Fc⑀RI-mediated signaling in mast cells (13). A requirement for myosin II is shown by the greatly diminished receptor redistributions and/or developments of cell polarity that have been observed in cells that either lack myosin II (14, 15) or express a dominant-negative mutant of myosin II function (16 -18). Erythrocyte spectrin (19) and the nonerythroid spectrin called fodrin 1 (20, 21) also have been implicated in lipid raft-mediated processes. Taken together, these observations suggest that actin filaments, perhaps as components of a spectrin-based membrane skeleton, are required for the

Electron microscope studies have shown that the switched-off state of myosin II in muscle involves intramolecular interaction between the two heads of myosin and between one head and the tail. The interaction, seen in both myosin filaments and isolated molecules, inhibits activity by blocking actin-binding and ATPase sites on myosin. This interacting-heads motif is highly conserved, occurring in invertebrates and vertebrates, in striated, smooth, and nonmuscle myosin IIs, and in myosins regulated by both Ca binding and regulatory light-chain phosphorylation. Our goal was to determine how early this motif arose by studying the structure of inhibited myosin II molecules from primitive animals and from earlier, unicellular species that predate animals. Myosin II from (sea anemones, jellyfish), the most primitive animals with muscles, and (sponges), the most primitive of all animals (lacking muscle tissue) showed the same interacting-heads structure as myosins from higher animals, confirming the early origin of the motif. The social amoeba showed a similar, but modified, version of the motif, while the amoeba and fission yeast () showed no head-head interaction, consistent with the different sequences and regulatory mechanisms of these myosins compared with animal myosin IIs. Our results suggest that head-head/head-tail interactions have been conserved, with slight modifications, as a mechanism for regulating myosin II activity from the emergence of the first animals and before. The early origins of these interactions highlight their importance in generating the inhibited (relaxed) state of myosin in muscle and nonmuscle cells.