NOS1AP associates with Scribble and regulates dendritic spine development

Rewiring cell polarity signaling in cancer

Disrupted cell polarity is a feature of epithelial cancers. The Crumbs, Par and Scribble polarity complexes function to specify and maintain apical and basolateral membrane domains, which are essential to organize intracellular signaling pathways that maintain epithelial homeostasis. Disruption of apical-basal polarity proteins facilitates rewiring of oncogene and tumor suppressor signaling pathways to deregulate proliferation, apoptosis, invasion and metastasis. Moreover, apical-basal polarity integrates intracellular signaling with the microenvironment by regulating metabolic signaling, extracellular matrix remodeling and tissue level organization. In this review, we discuss recent advances in our understanding of how polarity proteins regulate diverse signaling pathways throughout cancer progression from initiation to metastasis.

Generation of a cre recombinase-conditional Nos1ap over-expression transgenic mouse

Polymorphic non-coding variants at the NOS1AP locus have been associated with the common cardiac, metabolic and neurological traits and diseases. Although, in vitro gene targeting-based cellular and biochemical studies have shed some light on NOS1AP function in cardiac and neuronal tissue, to enhance our understanding of NOS1AP function in mammalian physiology and disease, we report the generation of cre recombinase-conditional Nos1ap over-expression transgenic mice (Nos1ap (Tg)). Conditional transgenic mice were generated by the pronuclear injection method and three independent, single-site, multiple copies integration event-based founder lines were selected. For heart-restricted over-expression, Nos1ap (Tg) mice were crossed with Mlc2v-cre and Nos1ap transcript over-expression was observed in left ventricles from Nos1ap (Tg); Mlc2v-cre F1 mice. We believe that with the potential of conditional over-expression, Nos1ap (Tg) mice will be a useful resource in studying NOS1AP function in various tissues under physiological and disease states.

NOS1AP is associated with increased severity of PTSD and depression in untreated combat veterans

BACKGROUND

Posttraumatic stress disorder (PTSD) and depressive disorder are over represented in combat veterans. Veterans with both disorders have an increased risk of suicide. The nitric oxide synthase 1 adaptor protein (NOS1AP) gene, which modulates stress-evoked N-methyl-d-aspartate (NMDA) activity, was investigated in combat veterans.

METHODS

A comprehensive genetic analysis of NOS1AP and its association with PTSD was investigated in Vietnam combat veterans with PTSD (n=121) and a group of healthy control individuals (n=237). PTSD patients were assessed for symptom severity and level of depression using the Mississippi Scale for Combat-Related PTSD and the Beck Depression Inventory-II (BDI).

RESULTS

The G allele of NOS1AP SNP rs386231 was significantly associated with PTSD (p=0.002). Analysis of variance revealed significant differences in BDI-II and Mississippi scores between genotypes for rs386231 with the GG genotype associated with increased severity of depression (p=0.002 F=6.839) and higher Mississippi Scale for Combat-Related PTSD scores (p=0.033). Haplotype analysis revealed that the C/G haplotype (rs451275/rs386231) was significantly associated with PTSD (p=0.001).

LIMITATIONS

The sample sizes in our study were not sufficient to detect SNP associations with very small effects. In addition the study was limited by its cross sectional design.

CONCLUSIONS

This is the first study reporting that a variant of the NOS1AP gene is associated with PTSD. Our data also suggest that a genetic variant in NOS1AP may increase the susceptibility to severe depression in patients with PTSD and increased risk for suicide.

A protein complex of SCRIB, NOS1AP and VANGL1 regulates cell polarity and migration, and is associated with breast cancer progression

By analyzing public data sets of gene expression in human breast cancers we observed that increased levels of transcripts encoding the planar cell polarity (PCP) proteins SCRIB and VANGL1 correlate with increased risk of patient relapse. Experimentally, we found that reducing expression of SCRIB by short-hairpin RNAs (shRNAs) reduces the growth of human breast cancer cells in xenograft assays. To investigate SCRIB-associated proteins that might participate in the responses of breast cancer cells to altered levels of SCRIB, we used mass spectrometry and confocal microscopy. These studies reveal that SCRIB is present in at least two unique protein complexes: (1) a complex of SCRIB, ARHGEF, GIT and PAK (p21-activated kinase), and (2) a complex of SCRIB, NOS1AP and VANGL. Focusing on NOS1AP, we observed that NOS1AP colocalizes with both SCRIB and VANGL1 along cellular protrusions in metastatic breast cancer cells, but does not colocalize with either SCRIB or VANGL1 at cell junctions in normal breast cells. We investigated the effects of shRNA-mediated knockdown of NOS1AP and SCRIB in vitro, and found that reducing NOS1AP and SCRIB slows breast cancer cell migration and prevents the establishment of leading-trailing polarity. We also find that reduction of NOS1AP enhances anchorage-independent growth. Collectively these data point to the relevance of NOS1AP and SCRIB protein complexes in breast cancer.

Research progress on neurobiology of neuronal nitric oxide synthase

Neuronal nitric oxide synthase (nNOS) is mainly expressed in neurons, to some extent in astrocytes and neuronal stem cells. The alternative splicing of nNOS mRNA generates 5 isoforms of nNOS, including nNOS-α, nNOS-β, nNOS-µ, nNOS-γ and nNOS-2. Monomer of nNOS is inactive, and dimer is the active form. Dimerization requires tetrahydrobiopterin (BH4), heme and L-arginine binding. Regulation of nNOS expression relies largely on cAMP response element-binding protein (CREB) activity, and nNOS activity is regulated by heat shock protein 90 (HSP90)/HSP70, calmodulin (CaM), phosphorylation and dephosphorylation at Ser847 and Ser1412, and the protein inhibitor of nNOS (PIN). There are primarily 9 nNOS-interacting proteins, including post-synaptic density protein 95 (PSD95), clathrin assembly lymphoid leukemia (CALM), calcium/calmodulin-dependent protein kinase II alpha (CAMKIIA), Disks large homolog 4 (DLG4), DLG2, 6-phosphofructokinase, muscle type (PFK-M), carboxy-terminal PDZ ligand of nNOS (CAPON) protein, syntrophin and dynein light chain (LC). Among them, PSD95, CAPON and PFK-M are important nNOS adapter proteins in neurons. The interaction of PSD95 with nNOS controls synapse formation and is implicated in N-methyl-D-aspartic acid-induced neuronal death. nNOS-derived NO is implicated in synapse loss-mediated early cognitive/motor deficits in several neuropathological states, and negatively regulates neurogenesis under physiological and pathological conditions.

Immature T-cell clustering and efficient differentiation require the polarity protein Scribble

T-cell polarization is required for cell migration and cell-cell interactions, cellular behaviors crucial for lymphocyte differentiation. Despite expression of the epithelial polarity network in T cells, neither its contribution to thymocyte polarity nor its requirement during development is known. We report here that depletion of the polarity protein Scribble in hematopoietic progenitor cells results in inefficient T-cell development characterized by a partial developmental block during the early double-negative (DN) stage of differentiation. Scribble-depleted hematopoietic progenitor cells exhibit a delayed transition into late CD44(lo/-)CD25(+) DN3 cells, evidenced by the accumulation of early CD44(int)CD25(+) DN3 cells. As a consequence, a limited cellular expansion and a reduced frequency of intracellular T-cell receptor β-positive DN3 cells are observed among Scribble-deficient differentiating T cells. Moreover, whereas purified Scribble-depleted DN2 and DN3 cells do not exhibit compromised spontaneous motility, T-cell clustering and prolonged homotypic interactions among such cells are reduced. This deficiency correlates with a lack of polarization of the integrin LFA-1 during T-cell migration or on the initiation of T-cell-T-cell interactions. Scribble is therefore a critical contributor to the clustering of immature T cells, an event shown here to be necessary for efficient developmental progression.

The planar polarity protein Scribble1 is essential for neuronal plasticity and brain function

Scribble (Scrib) is a key regulator of apicobasal polarity, presynaptic architecture, and short-term synaptic plasticity in Drosophila. In mammals, its homolog Scrib1 has been implicated in cancer, neural tube closure, and planar cell polarity (PCP), but its specific role in the developing and adult nervous system is unclear. Here, we used the circletail mutant, a mouse model for PCP defects, to show that Scrib1 is located in spines where it influences actin cytoskeleton and spine morphing. In the hippocampus of these mutants, we observed an increased synapse pruning associated with an increased number of enlarged spines and postsynaptic density, and a decreased number of perforated synapses. This phenotype was associated with a mislocalization of the signaling pathway downstream of Scrib1, leading to an overall activation of Rac1 and defects in actin dynamic reorganization. Finally, Scrib1-deficient mice exhibit enhanced learning and memory abilities and impaired social behavior, two features relevant to autistic spectrum disorders. Our data identify Scrib1 as a crucial regulator of brain development and spine morphology, and suggest that Scrib1(crc/+) mice might be a model for studying synaptic dysfunction and human psychiatric disorders.