Marble Burying and Nestlet Shredding as Tests of Repetitive, Compulsive-like Behaviors in Mice

Obsessive-compulsive disorder (OCD) and autism spectrum disorders (ASD) are serious and debilitating psychiatric conditions and each constitutes a ...

Wayne State University School of Medicine

Rab15 &#x662F;&#x65B0;&#x578B;&#x7684;&#x541E; Rab&#xFF0C;&#x8BA1;&#x6570;&#x5668;&#x5BF9;&#x65E9;&#x671F;&#x541E;&#x8D29;&#x8FD0; Rab5 GTP &#x7684;&#x523A;&#x6FC0;&#x5F71;&#x54CD;&#x3002;Rab15 &#x53EF;&#x80FD;&#x5E72;&#x6270; Rab5 &#x51FD;&#x6570;&#x7531;&#x6263;&#x62BC; Rab5 &#x4EA7;&#x751F;&#x5F71;&#x54CD;&#x7684;&#x624B;&#x6BB5;&#xFF0C;&#x76F4;&#x63A5;&#x6216;&#x95F4;&#x63A5;&#x5730;&#x901A;&#x8FC7;&#x5C0F;&#x8BF4;&#x8BBE;&#x7F6E;&#x6548;&#x5E94;&#x76F8;&#x4E92;&#x4F5C;&#x7528;&#x3002;&#x8981;&#x533A;&#x5206;&#x8FD9;&#x4E9B;&#x53EF;&#x80FD;&#x6027;&#xFF0C;&#x6211;&#x4EEC;&#x5BA1;&#x67E5;&#x4E86; Rab15 &#x7684;&#x6548;&#x5E94;&#x7ED1;&#x5B9A;&#x5C5E;&#x6027;&#x3002;Rab15 &#x4E0D;&#x76F4;&#x63A5;&#x4E0E; Rab5 &#x6548;&#x5E94;&#x5668; rabex-5 &#x548C; rabaptin-5 &#x5728;&#x9175;&#x6BCD;&#x53CC;&#x6742;&#x4EA4;&#x7ED3;&#x5408;&#x5206;&#x6790;&#x4EA4;&#x4E92;&#x3002;&#x800C;&#x54FA;&#x4E73;&#x52A8;&#x7269;&#x6291;&#x764C;&#x7684; Sec4 (Mss4) &#x88AB;&#x786E;&#x5B9A;&#x4E3A; Rab15 &#x7684;&#x4E00;&#x4E2A;&#x7ED1;&#x5B9A;&#x4F19;&#x4F34;&#x3002;Mss4 &#x4F18;&#x5148;&#x7ED1;&#x5B9A;&#x7ED1;&#x5B9A; GDP (T22N) &#x548C;&#x6838;&#x82F7;&#x9178;&#x514D;&#x8D39;&#x7684; (N121I) Rab15&#xFF0C;&#x7B26;&#x5408;&#x4F5C;&#x4E3A;&#x7A33;&#x5B9A;&#x7684;&#x4F34;&#x4FA3;&#x7684; Mss4 &#x62DF;&#x8BAE;&#x4F5C;&#x7528;&#x76EE;&#x6807; Rabs &#x5176;&#x65E0;&#x6838;&#x82F7;&#x9178;&#x7684;&#x7A97;&#x4F53;&#x4E2D;&#x3002;Rab15 &#x7A81;&#x53D8;&#x5206;&#x6790;&#x8868;&#x660E;&#xFF0C;&#x8D56;&#x6C28;&#x9178;&#x4F4D;&#x7F6E; 48 (K48Q) &#x662F;&#x7528;&#x4E8E;&#x7ED1;&#x5B9A;&#x5230; Mss4 Rab15-&#x56FD;&#x5185;&#x751F;&#x4EA7;&#x603B;&#x503C;&#x7684;&#x91CD;&#x8981;&#x3002;&#x6B64;&#x5916;&#xFF0C;K48Q &#x7A81;&#x53D8;&#x8BA1;&#x6570;&#x5668;&#x6291;&#x5236;&#x8868;&#x578B;&#x7684;&#x91CE;&#x751F;&#x578B; Rab15 &#x5BF9; HeLa &#x7EC6;&#x80DE;&#x548C;&#x540C;&#x578B; endosome &#x878D;&#x5408;&#x7EC6;&#x80DE;&#x53D7;&#x4F53;&#x4ECB;&#x5BFC;&#x5185;&#x541E;&#x4F5C;&#x7528;&#x800C;&#x4E0D;&#x6539;&#x53D8;&#x7EC6;&#x80DE;&#x8868;&#x9762;&#x76F8;&#x5173;&#x8F6C;&#x94C1;&#x86CB;&#x767D;&#x53D7;&#x4F53;&#x7684;&#x76F8;&#x5BF9;&#x91CF;&#x3002;&#x5728;&#x4E00;&#x8D77;&#xFF0C;&#x8FD9;&#x4E9B;&#x6570;&#x636E;&#x8868;&#x660E;&#x65B0;&#x578B;&#x4F5C;&#x7528;&#x7684; Mss4 &#x4F5C;&#x4E3A;&#x6548;&#x5E94;&#x4E3A; Rab15 &#x65E9;&#x671F;&#x541E;&#x8D29;&#x5356;&#x3002;

Sec4 &#x54FA;&#x4E73;&#x52A8;&#x7269;&#x6291;&#x5236;&#x56E0;&#x5B50;&#x5728;&#x65E9;&#x671F;&#x5185;&#x541E;&#x4F5C;&#x7528;&#x8C03;&#x8282; Rab15 &#x7684;&#x6291;&#x5236;&#x4F5C;&#x7528;&#x3002;

Rab15 is a novel endocytic Rab that counters the stimulatory effect of Rab5-GTP on early endocytic trafficking. Rab15 may interfere with Rab5 function directly by sequestering Rab5 effectors or indirectly through novel sets of effector interactions. To distinguish between these possibilities, we examined the effector binding properties of Rab15. Rab15 does not interact directly with the Rab5 effectors rabex-5 and rabaptin-5 in a yeast two-hybrid binding assay. Rather mammalian suppressor of Sec4 (Mss4) was identified as a binding partner for Rab15. Mss4 preferentially binds GDP-bound (T22N) and nucleotide-free (N121I) Rab15, consistent with the proposed role of Mss4 as a chaperone that stabilizes target Rabs in their nucleotide-free form. Mutational analysis of Rab15 indicates that lysine at position 48 (K48Q) is important for the binding of Rab15-GDP to Mss4. Moreover, the mutation K48Q counters the inhibitory phenotype of wild type Rab15 on receptor-mediated endocytosis in HeLa cells and homotypic endosome fusion in vitro without altering the relative amount of cell surface-associated transferrin receptor. Together, these data indicate a novel role for Mss4 as an effector for Rab15 in early endocytic trafficking.

Mammalian suppressor of Sec4 modulates the inhibitory effect of Rab15 during early endocytosis.

Rab15 est un roman Rab endocytose qui contrecarre l&#39;effet stimulateur de Rab5-GTP sur trafic endocytose pr&eacute;coce. Rab15 peut interf&eacute;rer avec la fonction Rab5 directement par s&eacute;questration effecteurs Rab5 ou indirectement par l&#39;interm&eacute;diaire de roman d&eacute;finit des interactions de l&#39;effecteur. Pour faire la diff&eacute;rence entre ces possibilit&eacute;s, nous avons &eacute;tudi&eacute; les propri&eacute;t&eacute;s de liaison d&#39;effecteur des Rab15. Rab15 n&#39;interagit pas directement avec les effecteurs Rab5 rabex-5 et 5-rabaptin dans un essai de liaison de deux-hybride de levure. Plut&ocirc;t mammif&egrave;re suppresseur de Sec4 (Mss4) a &eacute;t&eacute; identifi&eacute; comme un partenaire de liaison pour Rab15. MSS4 lie pr&eacute;f&eacute;rentiellement le PIB li&eacute; (T22N) et de nucl&eacute;otides libres (N121I) Rab15, conforme au r&ocirc;le propos&eacute; de Mss4 comme un chaperon qui stabilise sortie Rabs dans leur forme d&eacute;pourvue de nucl&eacute;otides. Analyse mutationnelle du Rab15 indique que la lysine &agrave; la position 48 (K48Q) est importante pour la liaison de Rab15 PIB pour Mss4. De plus, la mutation K48Q r&eacute;plique le ph&eacute;notype inhibiteur de type sauvage Rab15 sur l&#39;endocytose des r&eacute;cepteurs dans les cellules HeLa et homotypiques endosome fusion in vitro sans modifier la quantit&eacute; relative de r&eacute;cepteur de la transferrine associ&eacute;e &agrave; la surface de cellules. Ensemble, ces r&eacute;sultats indiquent un nouveau r&ocirc;le pour Mss4 comme effecteur pour Rab15 dans le trafic de l&#39;endocytose pr&eacute;coce.

Mammif&egrave;res suppresseur de Sec4 modulant l&#39;effet inhibiteur du Rab15 au cours de l&#39;endocytose pr&eacute;coce.

Mammalian Suppressor of Sec4 moduliert die hemmende Wirkung von Rab15 w&#xE4;hrend der fr&#xFC;hen Endozytose.

Rab15 &egrave; un romanzo endocitico Rab che contrasta l&#39;effetto stimolante del Rab5-GTP sulla tratta endocitico precoce. Rab15 pu&ograve; interferire con la funzione Rab5 direttamente sequestrando Rab5 effettori o indirettamente attraverso il romanzo imposta delle interazioni effettrici. Per distinguere tra queste possibilit&agrave;, abbiamo esaminato le propriet&agrave; di associazione effector di Rab15. Rab15 non interagisce direttamente con gli effettori Rab5 rabex 5 e rabaptin-5 in un dosaggio di associazione due-ibrido del lievito. Piuttosto dei mammiferi soppressore di Sec4 (Mss4) &egrave; stato identificato come un partner di associazione per Rab15. Mss4 si lega preferenzialmente PIL associati (T22N) e privo di nucleotide (N121I) Rab15, coerente con il ruolo proposto di Mss4 come un tuttofare che stabilizza target Rabs nella loro forma priva di nucleotidi. Analisi mutazionale di Rab15 indica che la lisina in posizione 48 (K48Q) &egrave; importante per l&#39;associazione di Rab15-PIL a Mss4. Inoltre, la mutazione K48Q contatori il fenotipo inibitorio del wild type Rab15 su endocitosi recettore-mediata di cellule HeLa e homotypic endosoma fusion in vitro senza alterare la relativa quantit&agrave; di recettore Transferrina associati di superficie delle cellule. Insieme, questi dati indicano un ruolo romanzo per Mss4 come un generatore di effetti per Rab15 nel traffico endocitico precoce.

Mammiferi soppressore di Sec4 modula l&#39;effetto inibitorio di Rab15 durante primi endocitosi.

Rab15 &#x521D;&#x671F;&#x30A8;&#x30F3;&#x30C9;&#x30B5;&#x30A4;&#x30C8;&#x30FC;&#x30B7;&#x30B9;&#x4EBA;&#x8EAB;&#x58F2;&#x8CB7; Rab5 GTP &#x306E;&#x4FC3;&#x9032;&#x52B9;&#x679C;&#x3092;&#x30AB;&#x30A6;&#x30F3;&#x30BF;&#x30FC;&#x5C0F;&#x8AAC;&#x306E;&#x30A8;&#x30F3;&#x30C9;&#x30B5;&#x30A4;&#x30C8;&#x30FC;&#x30B7;&#x30B9; Rab &#x3067;&#x3059;&#x3002;Rab15 Rab5 &#x95A2;&#x6570;&#x3092;&#x76F4;&#x63A5; Rab5 &#x30A8;&#x30D5;&#x30A7;&#x30AF;&#x30BF;&#x9694;&#x96E2;&#x3057;&#x3066;&#x75C5;&#x6C17;&#x3092;&#x59A8;&#x3052;&#x308B;&#x53EF;&#x80FD;&#x6027;&#x304C;&#x3042;&#x308A;&#x307E;&#x3059;&#x3002; &#x307E;&#x305F;&#x306F;&#x30A8;&#x30D5;&#x30A7;&#x30AF;&#x30BF;&#x30FC;&#x306E;&#x76F8;&#x4E92;&#x4F5C;&#x7528;&#x306E;&#x5C0F;&#x8AAC;&#x3092;&#x76F4;&#x63A5;&#x306B;&#x8A2D;&#x5B9A;&#x3057;&#x307E;&#x3059;&#x3002;&#x3053;&#x308C;&#x3089;&#x306E;&#x72B6;&#x6CC1;&#x3092;&#x533A;&#x5225;&#x3059;&#x308B;&#x306B;&#x306F;&#x3001;Rab15 &#x306E;&#x30A8;&#x30D5;&#x30A7;&#x30AF;&#x30BF;&#x30FC;&#x7D50;&#x5408;&#x7279;&#x6027;&#x3092;&#x691C;&#x8A0E;&#x3057;&#x307E;&#x3057;&#x305F;&#x3002;Rab15 rabex 5&#x3001;rabaptin-5 &#x9175;&#x6BCD; 2 &#x30CF;&#x30A4;&#x30D6;&#x30EA;&#x30C3;&#x30C9; &#x30D0;&#x30A4;&#x30F3;&#x30C7;&#x30A3;&#x30F3;&#x30B0; &#x30A2;&#x30C3;&#x30BB;&#x30A4;&#x3067;&#x306E; Rab5 &#x30A8;&#x30D5;&#x30A7;&#x30AF;&#x30BF;&#x3068;&#x76F4;&#x63A5;&#x3084;&#x308A;&#x53D6;&#x308A;&#x3057;&#x307E;&#x305B;&#x3093;&#x3002;Sec4 &#x306E;&#x3067;&#x306F;&#x306A;&#x304F;&#x54FA;&#x4E73;&#x985E;&#x30B5;&#x30D7;&#x30EC;&#x30C3;&#x30B5;&#x30FC; (Mss4) Rab15 &#x306E;&#x305F;&#x3081;&#x306E;&#x30D0;&#x30A4;&#x30F3;&#x30C7;&#x30A3;&#x30F3;&#x30B0;&#x306E;&#x30D1;&#x30FC;&#x30C8;&#x30CA;&#x30FC;&#x3068;&#x3057;&#x3066;&#x8B58;&#x5225;&#x3055;&#x308C;&#x307E;&#x3057;&#x305F;&#x3002;Mss4 &#x512A;&#x5148;&#x7684; GDP &#x7D50;&#x5408; (T22N) &#x3092;&#x30D0;&#x30A4;&#x30F3;&#x30C9;&#x3057;&#x3066; (N121I) Rab15&#x3001;Mss4 &#x5B89;&#x5B9A;&#x30B7;&#x30E3;&#x30DA;&#x30ED;&#x30F3;&#x3068;&#x3057;&#x3066;&#x63D0;&#x6848;&#x3055;&#x308C;&#x305F;&#x5F79;&#x5272;&#x3068;&#x4E00;&#x8CAB;&#x6027;&#x306E;&#x3042;&#x308B;&#x7121;&#x6599;&#x306E;&#x30CC;&#x30AF;&#x30EC;&#x30AA;&#x30C1;&#x30C9;&#x3092;&#x30BF;&#x30FC;&#x30B2;&#x30C3;&#x30C8; Rabs&#x3001;&#x7121;&#x6599;&#x306E;&#x5869;&#x57FA;&#x914D;&#x5217;&#x306E;&#x5F62;&#x3067;&#x3002;Rab15 &#x306E;&#x5909;&#x7570;&#x89E3;&#x6790;&#x306F;&#x305D;&#x306E;&#x30EA;&#x30B8;&#x30F3; (K48Q) &#x4F4D;&#x7F6E; 48 &#x91CD;&#x8981;&#x306E; Rab15-GDP Mss4 &#x3078;&#x306E;&#x30D0;&#x30A4;&#x30F3;&#x30C7;&#x30A3;&#x30F3;&#x30B0;&#x3092;&#x793A;&#x3057;&#x307E;&#x3059;&#x3002;&#x307E;&#x305F;&#x3001;&#x5909;&#x7570; K48Q &#x91CE;&#x751F;&#x578B; Rab15 &#x53D7;&#x5BB9;&#x4F53;&#x3092;&#x4ECB;&#x3057;&#x305F;&#x30A8;&#x30F3;&#x30C9;&#x30B5;&#x30A4;&#x30C8;&#x30FC;&#x30B7;&#x30B9; HeLa &#x7D30;&#x80DE;&#x3068; in vitro &#x30A8;&#x30CD;&#x30EB;&#x30AE;&#x30FC; &#x30A8;&#x30F3;&#x30C9;&#x30BD;&#x30FC;&#x30E0;&#x306E;&#x878D;&#x5408;&#x306E;&#x963B;&#x5BB3;&#x8868;&#x73FE;&#x578B;&#x306E;&#x7D30;&#x80DE;&#x8868;&#x9762;&#x306B;&#x95A2;&#x9023;&#x4ED8;&#x3051;&#x3089;&#x308C;&#x305F;&#x30C8;&#x30E9;&#x30F3;&#x30B9;&#x30D5;&#x30A7;&#x30EA;&#x30F3;&#x53D7;&#x5BB9;&#x4F53;&#x306E;&#x76F8;&#x5BFE;&#x91CF;&#x3092;&#x5909;&#x66F4;&#x3059;&#x308B;&#x3053;&#x3068;&#x306A;&#x304F;&#x304C;&#x30AB;&#x30A6;&#x30F3;&#x30BF;&#x30FC;&#x3057;&#x307E;&#x3059;&#x3002;&#x4E00;&#x7DD2;&#x306B;&#x3001;&#x3053;&#x308C;&#x3089;&#x306E;&#x30C7;&#x30FC;&#x30BF;&#x65B0;&#x898F;&#x5F79;&#x5272; Mss4 &#x306E;&#x30A8;&#x30D5;&#x30A7;&#x30AF;&#x30BF;&#x30FC;&#x3068;&#x3057;&#x3066; Rab15 &#x306E;&#x521D;&#x671F;&#x306E;&#x30A8;&#x30F3;&#x30C9;&#x30B5;&#x30A4;&#x30C8;&#x30FC;&#x30B7;&#x30B9;&#x4EBA;&#x8EAB;&#x58F2;&#x8CB7;&#x3067;&#x793A;&#x3057;&#x307E;&#x3059;&#x3002;

&#x54FA;&#x4E73;&#x985E;&#x306E;&#x6291;&#x5236; Sec4 &#x306E; Rab15 &#x306E;&#x6291;&#x5236;&#x52B9;&#x679C;&#x306E;&#x65E9;&#x671F;&#x306E;&#x30A8;&#x30F3;&#x30C9;&#x30B5;&#x30A4;&#x30C8;&#x30FC;&#x30B7;&#x30B9;&#x4E2D;&#x3067;&#x5909;&#x8ABF;&#x3057;&#x307E;&#x3059;&#x3002;

Rab15 &#xCD08;&#xAE30; endocytic &#xC778;&#xC2E0; &#xB9E4;&#xB9E4;&#xC5D0; Rab5-GTP&#xC758; stimulatory &#xD6A8;&#xACFC; &#xCE74;&#xC6B4;&#xD130; &#xC18C;&#xC124; endocytic &#xB7A9;&#xC785;&#xB2C8;&#xB2E4;. Rab15 Rab5 &#xC774;&#xD399;&#xD130; sequestering &#xC758;&#xD574; &#xC9C1;&#xC811; Rab5 &#xAE30;&#xB2A5;&#xC744; &#xBC29;&#xD574;&#xD560; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4; &#xD558;&#xAC70;&#xB098; &#xC9C1;&#xC811; &#xC18C;&#xC124;&#xC744; &#xD1B5;&#xD574; &#xC124;&#xC815; &#xD558;&#xC9C0; &#xC774;&#xD399;&#xD130; &#xC0C1;&#xD638; &#xC791;&#xC6A9;&#xC758;. &#xC774;&#xB7EC;&#xD55C; &#xAC00;&#xB2A5;&#xC131;&#xC744; &#xAD6C;&#xBD84; &#xD558; &#xC6B0;&#xB9AC; rab15&#xC758; &#xC774;&#xD399;&#xD130; &#xBC14;&#xC778;&#xB529; &#xC18D;&#xC131;&#xC744; &#xAC80;&#xC0AC; &#xD569;&#xB2C8;&#xB2E4;. Rab15 rabex-5, &#xD6A8; &#xBAA8; 2 &#xC7A1;&#xC885; &#xBC14;&#xC778;&#xB529; &#xBD84;&#xC11D; &#xACB0;&#xACFC;&#xC5D0;&#xC11C; rabaptin-5 Rab5 &#xC774;&#xD399;&#xD130;&#xC640; &#xC9C1;&#xC811; &#xC0C1;&#xD638; &#xC791;&#xC6A9; &#xD558;&#xC9C0; &#xC54A;&#xC2B5;&#xB2C8;&#xB2E4;. &#xC624;&#xD788;&#xB824; &#xD3EC;&#xC720;&#xB958; &#xC5B5;&#xC555;&#xC758; Sec4 (Mss4) rab15&#xC5D0; &#xB300; &#xD55C; &#xBC14;&#xC778;&#xB529; &#xD30C;&#xD2B8;&#xB108;&#xB85C; &#xD655;&#xC778; &#xB418;&#xC5C8;&#xB2E4;. Mss4&#xB294; &#xC6B0;&#xC120;&#xC801;&#xC73C;&#xB85C; GDP &#xBC14;&#xC778;&#xB529; (T22N) &#xBC14;&#xC778;&#xB529;&#xD558;&#xACE0; &#xB274;&#xD074;&#xB808;&#xC624;&#xD2F0;&#xB4DC; &#xBB34;&#xB8CC; (N121I) Rab15, &#xC548;&#xC815;&#xD654; &#xBCF4;&#xD638;&#xC790;&#xB85C; &#xC11C; mss4&#xC758; &#xC81C;&#xC548; &#xB41C; &#xC5ED;&#xD560;&#xACFC; &#xC77C;&#xCE58; &#xB274;&#xD074;&#xB808;&#xC624;&#xD2F0;&#xB4DC; &#xBB34;&#xB8CC; &#xD615;&#xD0DC;&#xB85C; Rabs&#xC744; &#xB300;&#xC0C1;. Rab15&#xC758; mutational &#xBD84;&#xC11D; 48 &#xC704;&#xCE58;&#xC758; &#xD574;&#xB2F9; lysine (K48Q) Mss4 Rab15-GDP&#xC758; &#xBC14;&#xC778;&#xB529;&#xC5D0; &#xB300; &#xD55C; &#xC911;&#xC694; &#xD55C; &#xB098;&#xD0C0;&#xB0C5;&#xB2C8;&#xB2E4;. &#xB610;&#xD55C;, K48Q &#xB3CC;&#xC5F0;&#xBCC0;&#xC774; &#xC138;&#xD3EC; &#xD45C;&#xBA74; &#xAD00;&#xB828; transferrin &#xC218;&#xC6A9; &#xCCB4;&#xC758; &#xC0C1;&#xB300;&#xC801; &#xD06C;&#xAE30;&#xB97C; &#xBCC0;&#xACBD; &#xD558;&#xC9C0; &#xC54A;&#xACE0; &#xC57C;&#xC0DD; &#xD0C0;&#xC785; Rab15 homotypic endosome &#xC735;&#xD569; &#xCCB4; &#xC678; HeLa &#xC138;&#xD3EC;&#xC5D0; &#xC218;&#xC6A9; &#xCCB4;-&#xC911;&#xC7AC; endocytosis&#xC5D0; &#xC5B5;&#xC81C; &#xD615; &#xCE74;&#xC6B4;&#xD130;. &#xD568;&#xAED8;, &#xC774;&#xB7EC;&#xD55C; &#xB370;&#xC774;&#xD130;&#xB97C; &#xB098;&#xD0C0;&#xB0B4;&#xB294; &#xC0C8;&#xB85C;&#xC6B4; &#xC5ED;&#xD560; mss4&#xC5D0; &#xB300; &#xD55C; &#xD55C; &#xC774;&#xD399;&#xD130;&#xB85C; rab15&#xC5D0; &#xB300; &#xD55C; &#xCD08;&#xAE30; endocytic &#xC778;&#xC2E0; &#xB9E4;&#xB9E4;.

Sec4&#xC758; &#xD3EC;&#xC720;&#xB958; &#xC5B5;&#xC555; &#xCD08;&#xAE30; endocytosis &#xB3D9;&#xC548; rab15&#xC758; &#xC5B5;&#xC81C; &#xD6A8;&#xACFC;&#xB97C; &#xBCC0;&#xC870; &#xD55C;&#xB2E4;.

Rab15 es una novela Rab endoc&iacute;ticas que contrarresta el efecto estimulante del Rab5-GTP en tr&aacute;fico endoc&iacute;tico temprano. Rab15 puede interferir con la funci&oacute;n Rab5 directamente por secuestro Rab5 efectores o indirectamente a trav&eacute;s de la novela establece de interacciones efectoras. Para distinguir entre estas posibilidades, examinamos las propiedades de enlace de efector de Rab15. Rab15 no interact&uacute;a directamente con los efectores Rab5 rabex-5 y rabaptin-5 en un ensayo de uni&oacute;n de dos h&iacute;bridos de levadura. M&aacute;s bien mam&iacute;fero supresor de Sec4 (Mss4) fue identificado como socio de la Uni&oacute;n de Rab15. Mss4 preferencial se une PIB-limite (T22N) y libre de nucle&oacute;tido (N121I) Rab15, consistente con el papel propuesto de Mss4 como un acompa&ntilde;ante que estabiliza blanco Rab en su forma libre de nucle&oacute;tido. El an&aacute;lisis mutacional de Rab15 indica que lisina en la posici&oacute;n 48 (K48Q) es importante para la Uni&oacute;n del Rab15-PIB a Mss4. Adem&aacute;s, la mutaci&oacute;n K48Q contra el fenotipo inhibitorio del tipo salvaje Rab15 en endocitosis mediada por receptor en las c&eacute;lulas HeLa y homot&iacute;picos endosome fusi&oacute;n in vitro sin alterar la cantidad relativa de receptor de transferrina asociada a superficie de la c&eacute;lula. Juntos, estos datos indican un papel nuevo para Mss4 como un generador de efectos para Rab15 en el tr&aacute;fico endoc&iacute;tico temprano.

Mam&iacute;fero supresor de Sec4 modula el efecto inhibitorio de Rab15 durante la endocitosis temprano.

Mephedrone (4-methylmethcathinone) is a β-ketoamphetamine with close structural analogy to substituted amphetamines and cathinone derivatives. Abuse of mephedrone has increased dramatically in recent years and has become a significant public health problem in the United States and Europe. Unfortunately, very little information is available on the pharmacological and neurochemical actions of mephedrone. In light of the proven abuse potential of mephedrone and considering its similarity to methamphetamine and methcathinone, it is particularly important to know if mephedrone shares with these agents an ability to cause damage to dopamine nerve endings of the striatum. Accordingly, we treated mice with a binge-like regimen of mephedrone (4 × 20 or 40 mg/kg) and examined the striatum for evidence of neurotoxicity 2 or 7 days after treatment. While mephedrone caused hyperthermia and locomotor stimulation, it did not lower striatal levels of dopamine, tyrosine hydroxylase or the dopamine transporter under any of the treatment conditions used presently. Furthermore, mephedrone did not cause microglial activation in striatum nor did it increase glial fibrillary acidic protein levels. Taken together, these surprising results suggest that mephedrone, despite its numerous mechanistic overlaps with methamphetamine and the cathinone derivatives, does not cause neurotoxicity to dopamine nerve endings of the striatum.

Mephedrone, an abused psychoactive component of 'bath salts' and methamphetamine congener, does not cause neurotoxicity to dopamine nerve endings of the striatum.

Neuropsychiatric disorders characterized by behavioral disinhibition, including disorders of compulsivity (e.g. obsessive-compulsive disorder; OCD) and impulse-control (e.g. impulsive aggression), are severe, highly prevalent and chronically disabling. Treatment options for these diseases are extremely limited. The pathophysiological bases of disorders of behavioral disinhibition are poorly understood but it has been suggested that serotonin dysfunction may play a role. Mice lacking the gene encoding brain tryptophan hydroxylase 2 (Tph2-/-), the initial and rate-limiting enzyme in the synthesis of serotonin, were tested in numerous behavioral assays that are well known for their utility in modeling human neuropsychiatric diseases. Mice lacking Tph2 (and brain 5HT) show intense compulsive and impulsive behaviors to include extreme aggression. The impulsivity is motor in form and not cognitive because Tph2-/- mice show normal acquisition and reversal learning on a spatial learning task. Restoration of 5HT levels by treatment of Tph2-/- mice with its immediate precursor 5-hydroxytryptophan attenuated compulsive and impulsive-aggressive behaviors. Surprisingly, in Tph2-/- mice, the lack of 5HT was not associated with anxiety-like behaviors. The results indicate that 5HT mediates behavioral disinhibition in the mammalian brain independent of anxiogenesis.

Genetic depletion of brain 5HT reveals a common molecular pathway mediating compulsivity and impulsivity.

Blast overpressure has long been known to cause barotrauma to air-filled organs such as lung and middle ear. However, experience in Iraq and Afghanistan is revealing that individuals exposed to explosive munitions can also suffer traumatic brain injury (TBI) even in the absence of obvious external injury. The interaction of a blast shock wave with the brain in the intact cranial vault is extremely complex making it difficult to conclude that a blast wave interacts in a direct manner with the brain to cause injury. In an attempt to "isolate" the shock wave and test its primary effects on cells, we exposed cultured microglia to simulated blast overpressure in a barochamber. Overpressures ranging from 15 to 45 psi did not change microglial Cox-2 levels or TNF-α secretion nor did they cause cell damage. Microarray analysis revealed increases in expression of a number of microglial genes relating to immune function and inflammatory responses to include Saa3, Irg1, Fas and CxCl10. All changes in gene expression were dependent on pulse duration and were independent of pressure. These results indicate that microglia are mildly activated by blast overpressure and uncover a heretofore undocumented role for pulse duration in this process.

Altered gene expression in cultured microglia in response to simulated blast overpressure: possible role of pulse duration.

Autism is a complex neurodevelopmental disorder characterized by impaired reciprocal social interaction, communication deficits and repetitive behaviors. A very large number of genes have been linked to autism, many of which encode proteins involved in the development and function of synaptic circuitry. However, the manner in which these mutated genes might participate, either individually or together, to cause autism is not understood. One factor known to exert extremely broad influence on brain development and network formation, and which has been linked to autism, is the neurotransmitter serotonin. Unfortunately, very little is known about how alterations in serotonin neuronal function might contribute to autism. To test the hypothesis that serotonin dysfunction can contribute to the core symptoms of autism, we analyzed mice lacking brain serotonin (via a null mutation in the gene for tryptophan hydroxylase 2 (TPH2)) for behaviors that are relevant to this disorder. Mice lacking brain serotonin (TPH2-/-) showed substantial deficits in numerous validated tests of social interaction and communication. These mice also display highly repetitive and compulsive behaviors. Newborn TPH2-/- mutant mice show delays in the expression of key developmental milestones and their diminished preference for maternal scents over the scent of an unrelated female is a forerunner of more severe socialization deficits that emerge in weanlings and persist into adulthood. Taken together, these results indicate that a hypo-serotonin condition can lead to behavioral traits that are highly characteristic of autism. Our findings should stimulate new studies that focus on determining how brain hyposerotonemia during critical neurodevelopmental periods can alter the maturation of synaptic circuits known to be mis-wired in autism and how prevention of such deficits might prevent this disorder.

Mice genetically depleted of brain serotonin display social impairments, communication deficits and repetitive behaviors: possible relevance to autism.

Mephedrone (4-methylmethcathinone) is a β-ketoamphetamine stimulant drug of abuse with close structural and mechanistic similarities to methamphetamine. One of the most powerful actions associated with mephedrone is the ability to stimulate dopamine (DA) release and block its re-uptake through its interaction with the dopamine transporter (DAT). Although mephedrone does not cause toxicity to DA nerve endings, its ability to serve as a DAT blocker could provide protection against methamphetamine-induced neurotoxicity like other DAT inhibitors. To test this possibility, mice were treated with mephedrone (10, 20, or 40 mg/kg) prior to each injection of a neurotoxic regimen of methamphetamine (four injections of 2.5 or 5.0 mg/kg at 2 h intervals). The integrity of DA nerve endings of the striatum was assessed through measures of DA, DAT, and tyrosine hydroxylase levels. The moderate to severe DA toxicity associated with the different doses of methamphetamine was not prevented by any dose of mephedrone but was, in fact, significantly enhanced. The hyperthermia caused by combined treatment with mephedrone and methamphetamine was the same as seen after either drug alone. Mephedrone also enhanced the neurotoxic effects of amphetamine and 3,4-methylenedioxymethamphetamine on DA nerve endings. In contrast, nomifensine protected against methamphetamine-induced neurotoxicity. As mephedrone increases methamphetamine neurotoxicity, the present results suggest that it interacts with the DAT in a manner unlike that of other typical DAT inhibitors. The relatively innocuous effects of mephedrone alone on DA nerve endings mask a potentially dangerous interaction with drugs that are often co-abused with it, leading to heightened neurotoxicity.

Mephedrone does not damage dopamine nerve endings of the striatum, but enhances the neurotoxicity of methamphetamine, amphetamine, and MDMA.

Mephedrone is a stimulant drug of abuse with close structural and mechanistic similarities to methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA). Although mephedrone does not damage dopamine nerve endings it increases the neurotoxicity of amphetamine, methamphetamine and MDMA. The effects of mephedrone on serotonin (5HT) nerve endings are not fully understood, with some investigators reporting damage while others conclude it does not. Presently, we investigate if mephedrone given alone or with methamphetamine or MDMA damages 5HT nerve endings of the hippocampus.

Effects of combined treatment with mephedrone and methamphetamine or 3,4-methylenedioxymethamphetamine on serotonin nerve endings of the hippocampus.

Our study was designed to determine if central nervous system serotonin is required for the induction of ventilatory long-term facilitation (LTF) in intact spontaneously breathing mice. Nineteen tryptophan hydroxylase 2 deficient (Tph2(-/-)) mice, devoid of serotonin in the central nervous system, and their wild type counterparts (Tph2(+/+)) were exposed to intermittent hypoxia each day for 10 consecutive days. Ventilatory LTF, caused by increases in breathing frequency, was evident in Tph2(+/+) and Tph2(-/-) mice following exposure to intermittent hypoxia each day; however, the magnitude of the response was greater in the Tph2(+/+) compared to the Tph2(-/-) mice (1.11 ± 0.02 vs. 1.05 ± 0.01 - normalized to baseline on each day; p = 0.01). The magnitude of ventilatory LTF increased significantly from the initial to the finals days of the protocol in the Tph2(-/-) (1.06 ± 0.02 vs. 1.11 ± 0.03 - normalized to baseline on the initial days; p = 0.004) but not in the Tph2(+/+) mice. This enhanced response was mediated by increases in tidal volume. We conclude that ventilatory LTF after acute exposure to intermittent hypoxia is mediated by increases in breathing frequency and occurs in the absence of serotonin; although the magnitude of the response is diminished. This weakened response is enhanced following repeated daily exposure to intermittent hypoxia, via increases in tidal volume, to a similar magnitude evident in Tph2(+/+) mice. Thus, the magnitude of ventilatory LTF following repeated daily exposure to intermittent hypoxia may not be dependent on the presence of central nervous system serotonin.

Ventilatory long-term facilitation is evident after initial and repeated exposure to intermittent hypoxia in mice genetically depleted of brain serotonin.

Dina M. Francescutti

Research and Development Service,
John D. Dingell VA Medical Center and Department of Psychiatry & Behavioral Neurosciences,
Research and Development Service, John D. Dingell VA Medical Center and Department of Psychiatry & Behavioral Neurosciences

Wayne State University School of Medicine

Marble Burying and Nestlet Shredding as Tests of Repetitive, Compulsive-like Behaviors in Mice