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1.
Nat Commun ; 12(1): 2083, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33828096

RESUMO

While Delta non-autonomously activates Notch in neighboring cells, it autonomously inactivates Notch through cis-inhibition, the molecular mechanism and biological roles of which remain elusive. The wave of differentiation in the Drosophila brain, the 'proneural wave', is an excellent model for studying Notch signaling in vivo. Here, we show that strong nonlinearity in cis-inhibition reproduces the second peak of Notch activity behind the proneural wave in silico. Based on this, we demonstrate that Delta expression induces a quick degradation of Notch in late endosomes and the formation of the twin peaks of Notch activity in vivo. Indeed, the amount of Notch is upregulated and the twin peaks are fused forming a single peak when the function of Delta or late endosomes is compromised. Additionally, we show that the second Notch peak behind the wavefront controls neurogenesis. Thus, intracellular trafficking of Notch orchestrates the temporal dynamics of Notch activity and the temporal patterning of neurogenesis.


Assuntos
Encéfalo/metabolismo , Proteínas de Drosophila/metabolismo , Transporte Proteico/fisiologia , Receptores Notch/metabolismo , Animais , Diferenciação Celular , Drosophila melanogaster , Endossomos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Silenciamento de Genes , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Neurogênese , Transporte Proteico/genética , Transdução de Sinais , Fatores de Transcrição , Proteínas rab de Ligação ao GTP/genética , Proteínas rab4 de Ligação ao GTP/genética
2.
Biomed Res Int ; 2021: 6662612, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33880375

RESUMO

miRNAs pose a good prospect in the diagnosis and treatment of type 2 diabetes (T2D). This study is aimed at investigating whether miR-720 targets Rab35 to regulate insulin secretion in MIN6 cells and its molecular mechanism and the clinical value of miR-720 as a specific biomarker of T2D. Fifty-five samples of new diagnosis T2D patients and normal control were collected. Levels of miR-720, fasting blood glucose, insulin, and other indicators of glucose and lipid metabolism were determined. We increased and decreased the miR-720 expression using miR-720 mimic and inhibitor to identify the effect of miR-720 on insulin secretion in MIN6 cells, respectively. Then, we used miR-720 mimic, miR-720 inhibitor, and dual luciferase reporter gene assays to prove miR-720 which regulates insulin secretion by targeting Rab35 in MIN6 cells. In addition, we overexpressed and silenced the Rab35 gene to detect the expression of PI3K, Akt, and mTOR in MIN6 cells by RT-PCR and western blot. In this study, circulating miR-720 was significantly higher in the T2D group than the control group, and miR-270 was positive correlated with FBG, while negatively correlated with FINS. The overexpression of miR-720 inhibited insulin secretion, and miR-720 downregulation promoted insulin secretion. miR-720 regulated insulin secretion by targeting Rab35 in MIN6 cells. Compared with the control group, the expression of PI3K, Akt, and mTOR was significantly decreased by the overexpression of the Rab35 gene, while the silencing Rab35 gene could induce the expression of PI3K, Akt, and mTOR. Furthermore, miR-720 mimic could activate the PI3K pathway. We conclude that miR-720 may be a potential biomarker for the diagnosis of T2D. Increase of miR-720 reduced the Rab35 expression then activate the PI3K/Akt/mTOR signal pathway, thus inhibiting insulin secretion.


Assuntos
Secreção de Insulina/genética , MicroRNAs/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Adulto , Idoso , Animais , Estudos de Casos e Controles , Linhagem Celular , MicroRNA Circulante/sangue , MicroRNA Circulante/genética , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/genética , Feminino , Humanos , Masculino , Camundongos , MicroRNAs/sangue , MicroRNAs/genética , Pessoa de Meia-Idade , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Adulto Jovem , Proteínas rab de Ligação ao GTP/genética
3.
Nat Commun ; 12(1): 841, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33547291

RESUMO

A new life begins with the unification of the maternal and paternal chromosomes upon fertilization. The parental chromosomes first become enclosed in two separate pronuclei near the surface of the fertilized egg. The mechanisms that then move the pronuclei inwards for their unification are only poorly understood in mammals. Here, we report two mechanisms that act in concert to unite the parental genomes in fertilized mouse eggs. The male pronucleus assembles within the fertilization cone and is rapidly moved inwards by the flattening cone. Rab11a recruits the actin nucleation factors Spire and Formin-2 into the fertilization cone, where they locally nucleate actin and further accelerate the pronucleus inwards. In parallel, a dynamic network of microtubules assembles that slowly moves the male and female pronuclei towards the cell centre in a dynein-dependent manner. Both mechanisms are partially redundant and act in concert to unite the parental pronuclei in the zygote's centre.


Assuntos
Núcleo Celular/metabolismo , Fertilização/genética , Forminas/genética , Proteínas dos Microfilamentos/genética , Proteínas do Tecido Nervoso/genética , Zigoto/metabolismo , Proteínas rab de Ligação ao GTP/genética , Actinas/genética , Actinas/metabolismo , Animais , Núcleo Celular/ultraestrutura , Feminino , Forminas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Genes Reporter , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Proteínas dos Microfilamentos/metabolismo , Microtúbulos/metabolismo , Microtúbulos/ultraestrutura , Movimento , Proteínas do Tecido Nervoso/metabolismo , Oócitos/metabolismo , Oócitos/ultraestrutura , Espermatozoides/metabolismo , Espermatozoides/ultraestrutura , Zigoto/ultraestrutura , Proteínas rab de Ligação ao GTP/metabolismo
4.
Yi Chuan ; 43(1): 16-29, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33509771

RESUMO

The intracellular membrane trafficking is a complicated pathway network. Rab GTPases are key regulators of membrane trafficking that are generally considered as specific markers and indicators of various organelles and membrane trafficking in endocytic and secretory pathways. Dysfunction in axonal and endosomal transport related to Rab proteins is one of the most important causes of neurodegenerative diseases. In this review, we mainly introduce how the Rab proteins change in different neurodegenerative diseases and their regulatory roles in the pathological mechanisms of related diseases. We also discuss the relationships between mitochondrial and glial cell dysfunctions and Rab proteins. Further exploration of the regulatory roles of Rab proteins will shed lights on revealing the pathogenic mechanisms of neurological diseases and providing potential targets for the early diagnosis and treatment of neurological diseases.


Assuntos
Doenças Neurodegenerativas , Proteínas rab de Ligação ao GTP , Humanos , Mitocôndrias , Doenças Neurodegenerativas/genética , Neuroglia , Transporte Proteico , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
5.
Dev Cell ; 56(1): 52-66.e7, 2021 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-33434526

RESUMO

ER tubules form and maintain membrane contact sites (MCSs) with endosomes. How and why these ER-endosome MCSs persist as endosomes traffic and mature is poorly understood. Here we find that a member of the reticulon protein family, Reticulon-3L (Rtn3L), enriches at ER-endosome MCSs as endosomes mature. We show that this localization is due to the long divergent N-terminal cytoplasmic domain of Rtn3L. We found that Rtn3L is recruited to ER-endosome MCSs by endosomal protein Rab9a, which marks a transition stage between early and late endosomes. Rab9a utilizes an FSV region to recruit Rtn3L via its six LC3-interacting region motifs. Consistent with our localization results, depletion or deletion of RTN3 from cells results in endosome maturation and cargo sorting defects, similar to RAB9A depletion. Together our data identify a tubular ER protein that promotes endosome maturation at ER MCSs.


Assuntos
Proteínas de Transporte/metabolismo , Retículo Endoplasmático/metabolismo , Endossomos/metabolismo , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Transporte Proteico/genética , Motivos de Aminoácidos , Autofagossomos/genética , Autofagossomos/metabolismo , Sistemas CRISPR-Cas , Proteínas de Transporte/genética , Linhagem Celular Tumoral , Retículo Endoplasmático/genética , Endossomos/genética , Técnicas de Silenciamento de Genes , Técnicas de Inativação de Genes , Humanos , Lisossomos/genética , Lisossomos/metabolismo , Proteínas de Membrana/genética , Microtúbulos/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas Nogo/genética , Proteínas Nogo/metabolismo , RNA Interferente Pequeno , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
6.
Neoplasma ; 68(2): 391-403, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33440987

RESUMO

Circular RNAs (circRNAs) play a crucial role in tumor occurrence and progression. And the dysregulated circRNAs are reported to be relevant to glioma development. Nevertheless, the function and regulatory mechanism of hsa_circ_0030018 in glioma progression are largely indistinct. The abundances of hsa_circ_0030018, miR-1297, and RAB21 were detected using quantitative real-time polymerase chain reaction or western blot. Cell proliferation was assessed via colony formation assay and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Cell apoptosis and cell cycle progression were evaluated by flow cytometry. Cell migration and invasion were examined using transwell assay and wound healing assay. The protein levels were measured by western blot. The interaction between miR-1297 and hsa_circ_0030018 or RAB21 was validated via dual-luciferase reporter analysis, RNA immunoprecipitation (RIP), and RNA pull-down assays. A xenograft model experiment was performed to analyze the function of hsa_circ_0030018 on tumor growth in vivo. hsa_circ_0030018 and RAB21 levels were enhanced, and the miR-1297 level was reduced in glioma tissues and cells. The silence of hsa_circ_0030018 or overexpression of miR-1297 impeded cell proliferation, metastasis, and expedited cell apoptosis and cycle arrest in glioma cells. Furthermore, hsa_circ_0030018 modulated glioma malignant behaviors via sponging miR-1297, and miR-1297 suppressed glioma development via targeting RAB21. Moreover, hsa_circ_0030018 knockdown inhibited tumor growth in vivo. The hsa_circ_0030018 knockdown repressed glioma progression by mediating the miR-1297/RAB21 pathway, providing potential therapeutic targets for glioma treatment.


Assuntos
Glioma , MicroRNAs , Movimento Celular/genética , Proliferação de Células/genética , Glioma/genética , Humanos , MicroRNAs/genética , RNA Circular , Proteínas rab de Ligação ao GTP/genética
7.
Methods Mol Biol ; 2233: 193-202, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33222136

RESUMO

Neutrophils are short-lived cells after isolation. The analysis of neutrophil vesicular trafficking requires rapid and gentle handling. Recently developed super-resolution microscopy technologies have generated unparalleled opportunities to help understand the molecular mechanisms regulating neutrophil vesicular trafficking, exocytosis, and associated functions at the molecular level. Here, we describe super-resolution and total internal reflection fluorescence (TIRF) microscopy approaches for the analysis of vesicular trafficking and associated functions of primary neutrophils.


Assuntos
Exocitose/genética , Microscopia de Fluorescência/métodos , Neutrófilos/ultraestrutura , Cultura Primária de Células/métodos , Movimento Celular/genética , Humanos , Neutrófilos/metabolismo , Transporte Proteico/genética , Proteínas rab de Ligação ao GTP/genética
8.
Biochim Biophys Acta Mol Cell Res ; 1868(1): 118857, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32949647

RESUMO

Intracellular organelle cross-talk is a new and important research area. Under stress conditions, the coordinated action of the autophagy and endosomal systems in tumor cells is essential for maintaining cellular homeostasis and survival. The activation of the IκB kinase (IKK) complex is also involved in the regulation of stress and homeostasis in tumor cells. Here, we try to explore the effects of constitutively active IKKß subunits (CA-IKKß) on autophagy and endosomal system interactions. We confirm that CA-IKKß induces accumulation of autophagosomes and their fusion with MVBs to form amphisomes in cancer cells, and also drives the release of EVs containing autophagy components through an amphisome-dependent mechanism. We further demonstrate that CA-IKKß inhibits the expression of RAB7, thereby weakening the lysosomal-dependent degradation pathway. CA-IKKß also induces phosphorylation of SNAP23 at Ser95 instead of Ser110, which further promotes amphisome-plasma membrane fusion and sEV secretion. These results indicate that CA-IKKß drives the formation and transport of amphisomes, thereby regulating tumor cell homeostasis, which may illuminate a special survival mechanism in tumor cells under stress.


Assuntos
Autofagia/genética , Quinase I-kappa B/genética , Proteínas Qb-SNARE/genética , Proteínas Qc-SNARE/genética , Proteínas rab de Ligação ao GTP/genética , Autofagossomos/genética , Linhagem Celular Tumoral , Endossomos/genética , Exocitose/genética , Vesículas Extracelulares/genética , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Lisossomos/genética , Fusão de Membrana/genética , Neoplasias/genética , Neoplasias/patologia , Fosforilação/genética , Transdução de Sinais/genética
9.
Exp Cell Res ; 399(2): 112442, 2021 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-33359467

RESUMO

Rab30 is a poorly characterized small GTPase. Here we show that Rab30 is localised primarily to the TGN and recycling endosomes in a range of cell types, including primary neurons; minor levels of Rab30 were also detected throughout the Golgi stack and early endosomes. Silencing of Rab30 resulted in the dispersal of both early and recycling endosomes and TGN compartments in HeLa cells. By analyzing cargo trafficking in Rab30-silenced and Rab30-overexpressing HeLa cells, we demonstrate that Rab30 plays a role in retrograde trafficking of TGN38 from endosomes to the Golgi, but has no apparent role in the endocytic recycling of the transferrin receptor to the plasma membrane. Five interactive partners with Rab30 were identified by pull-down and MS analysis using GFP-tagged Rab30 mutant, Rab30(Q68L). Two of the interactive partners identified were Arf1 and Arf4, known regulators of endosome to TGN retrograde transport. Knockdown of Arf1 and Arf4 results in GFP-Rab30 decorated tubules arising from the recycling endosomes, suggesting association of Rab30 with tubular carriers. Overall our data demonstrates a role for Rab30 in regulating retrograde transport to the TGN and maintenance of endosomal-TGN organization.


Assuntos
Endossomos/metabolismo , Proteínas rab de Ligação ao GTP/fisiologia , Rede trans-Golgi/genética , Antígenos CD/metabolismo , Endossomos/genética , Complexo de Golgi/metabolismo , Células HeLa , Humanos , Transporte Proteico/genética , Receptores da Transferrina/metabolismo , Proteínas rab de Ligação ao GTP/genética , Rede trans-Golgi/metabolismo
10.
Development ; 147(24)2020 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-33361092

RESUMO

Using the zebrafish neural tube as a model, we uncover the in vivo mechanisms allowing the generation of two opposing apical epithelial surfaces within the centre of an initially unpolarised, solid organ. We show that Mpp5a and Rab11a play a dual role in coordinating the generation of ipsilateral junctional belts whilst simultaneously releasing contralateral adhesions across the centre of the tissue. We show that Mpp5a- and Rab11a-mediated resolution of cell-cell adhesions are both necessary for midline lumen opening and contribute to later maintenance of epithelial organisation. We propose that these roles for both Mpp5a and Rab11a operate through the transmembrane protein Crumbs. In light of a recent conflicting publication, we also clarify that the junction-remodelling role of Mpp5a is not specific to dividing cells.


Assuntos
Guanilato Ciclase/genética , Morfogênese/genética , Proteínas de Peixe-Zebra/genética , Peixe-Zebra/crescimento & desenvolvimento , Proteínas rab de Ligação ao GTP/genética , Animais , Polaridade Celular/genética , Células Epiteliais/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Junções Intercelulares/genética , Proteínas de Membrana , Tubo Neural/crescimento & desenvolvimento , Peixe-Zebra/genética
11.
Sci Rep ; 10(1): 21858, 2020 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-33318498

RESUMO

A signalling pathway involving PLEKHG5 (guanine exchange factor) for the Ras superfamily member RAB26 to transcription factor NF-κB was discovered in autophagy. PLEKHG5 was reported in glioblastoma multiforme (GBM) and correlates with patient survival. Thus, the generation of a cellular model for understanding PLEKHG5 signalling is the study purpose. We generated a CRISPR/Cas9-mediated knockout of PLEKHG5 in U251-MG glioblastoma cells and analysed resulting changes. Next, we used a mRFP-GFP-LC3+ reporter for visualisation of autophagic defects and rescued the phenotype of PLEKHG5 wildtype via transduction of a constitutively active RAB26QL-plasmid. Effects of overexpressing RAB26 were investigated and correlated with the O6-methylguanine-DNA methyltransferase (MGMT) and cellular survival. PLEKHG5 knockout showed changes in morphology, loss of filopodia and higher population doubling times. Accumulation of autolysosomes was resulted by decreased LAMP-1 in PLEKHG5-deficient cells. Rescue of PLEKHG5-/- restored the downregulation of RhoA activity, showed faster response to tumour necrosis factor and better cellular fitness. MGMT expression was activated after RAB26 overexpression compared to non-transduced cells. Survival of PLEKHG5 knockout was rescued together with sensitivity to temozolomide by RAB26QL. This study provides new insights in the PLEKHG5/RAB26 signalling within U251-MG cells, which suggests potential therapeutic strategies in other glioma cells and further in primary GBM.


Assuntos
Autofagia , Metilases de Modificação do DNA/biossíntese , Enzimas Reparadoras do DNA/biossíntese , Regulação Neoplásica da Expressão Gênica , Glioblastoma/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Transdução de Sinais , Proteínas Supressoras de Tumor/biossíntese , Linhagem Celular Tumoral , Sobrevivência Celular , Metilases de Modificação do DNA/genética , Enzimas Reparadoras do DNA/genética , Técnicas de Inativação de Genes , Glioblastoma/genética , Glioblastoma/patologia , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Proteínas Supressoras de Tumor/genética , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo , Proteína rhoA de Ligação ao GTP/genética , Proteína rhoA de Ligação ao GTP/metabolismo
12.
PLoS Pathog ; 16(8): e1008822, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32866204

RESUMO

Shigella flexneri invades host cells by entering within a bacteria-containing vacuole (BCV). In order to establish its niche in the host cytosol, the bacterium ruptures its BCV. Contacts between S. flexneri BCV and infection-associated macropinosomes (IAMs) formed in situ have been reported to enhance BCV disintegration. The mechanism underlying S. flexneri vacuolar escape remains however obscure. To decipher the molecular mechanism priming the communication between the IAMs and S. flexneri BCV, we performed mass spectrometry-based analysis of the magnetically purified IAMs from S. flexneri-infected cells. While proteins involved in host recycling and exocytic pathways were significantly enriched at the IAMs, we demonstrate more precisely that the S. flexneri type III effector protein IpgD mediates the recruitment of the exocyst to the IAMs through the Rab8/Rab11 pathway. This recruitment results in IAM clustering around S. flexneri BCV. More importantly, we reveal that IAM clustering subsequently facilitates an IAM-mediated unwrapping of the ruptured vacuole membranes from S. flexneri, enabling the naked bacterium to be ready for intercellular spread via actin-based motility. Taken together, our work untangles the molecular cascade of S. flexneri-driven host trafficking subversion at IAMs to develop its cytosolic lifestyle, a crucial step en route for infection progression at cellular and tissue level.


Assuntos
Disenteria Bacilar , Shigella flexneri , Transdução de Sinais , Vacúolos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Disenteria Bacilar/genética , Disenteria Bacilar/metabolismo , Células HeLa , Humanos , Shigella flexneri/genética , Shigella flexneri/metabolismo , Shigella flexneri/patogenicidade , Vacúolos/genética , Vacúolos/metabolismo , Vacúolos/microbiologia , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
13.
Nat Commun ; 11(1): 4187, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32826901

RESUMO

EHBP1 is an adaptor protein that regulates vesicular trafficking by recruiting Rab8 family members and Eps15-homology domain-containing proteins 1/2 (EHD1/2). It also links endosomes to the actin cytoskeleton. However, the underlying molecular mechanism of activation of EHBP1 actin-binding activity is unclear. Here, we show that both termini of EHBP1 have membrane targeting potential. EHBP1 associates with PI(3)P, PI(5)P, and phosphatidylserine via its N-terminal C2 domain. We show that in the absence of Rab8 family members, the C-terminal bivalent Mical/EHBP Rab binding (bMERB) domain forms an intramolecular complex with its central calponin homology (CH) domain and auto-inhibits actin binding. Rab8 binding to the bMERB domain relieves this inhibition. We have analyzed the CH:bMERB auto-inhibited complex and the active bMERB:Rab8 complex biochemically and structurally. Together with structure-based mutational studies, this explains how binding of Rab8 frees the CH domain and allows it to interact with the actin cytoskeleton, leading to membrane tubulation.


Assuntos
Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Proteínas dos Microfilamentos/química , Proteínas dos Microfilamentos/metabolismo , Proteínas rab de Ligação ao GTP/química , Proteínas rab de Ligação ao GTP/metabolismo , Citoesqueleto de Actina/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Transporte/genética , Proteínas dos Microfilamentos/genética , Modelos Moleculares , Fosfatos de Fosfatidilinositol/metabolismo , Ligação Proteica , Conformação Proteica , Domínios Proteicos , Domínios e Motivos de Interação entre Proteínas , Transporte Proteico/fisiologia , Alinhamento de Sequência , Proteínas de Transporte Vesicular , Proteínas rab de Ligação ao GTP/genética
14.
Parasitol Res ; 119(9): 2991-3003, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32748038

RESUMO

Visceral leishmaniasis (VL, also known as kala-azar) is a vector borne disease caused by obligate intracellular protozoan parasite Leishmania donovani. To overcome the limitations of currently available drugs for VL, molecular target-based study is a promising tool to develop new drugs to treat this neglected tropical disease. One such target we recently identified from L. donovani (Ld) genome (WGS, clinical Indian isolate; BHU 1220, AVPQ01000001) is a small GTP-binding protein, Rab6 protein. We now report a specific inhibitor of the GTPase activity of Rab6 protein of L. donovani (LdRab6) without restricting host enzyme activity. First, to understand the nature of LdRab6 protein, we generated recombinant LdRab6 mutant proteins (rLdRab6) by systematically introducing deletion (two cysteine residues at C-terminal) and mutations [single amino acid substitutions in the conserved region of GTP (Q84L)/GDP(T38N) coding sequence]. The GTPase activity of rLdRab6:GTP and rLdRab6:GDP locked mutant proteins showed ~ 8-fold and ~ 1.5-fold decreases in enzyme activity, respectively, compared to the wild type enzyme activity. The mutant protein rLdRab6:ΔC inhibited the GTPase activity. Sequence alignment analysis of Rab6 protein of L. donovani with Homo sapiens showed identical amino acids in the G conserved region (GTP/GDP-binding sites) but it differed in the C-terminal region. We then evaluated the inhibitory activity of trans-dibenzalacetone (DBA, a synthetic analog of curcumin with strong antileishmanial activity reported earlier by us) in the GTPase activity of LdRab6 protein. Comparative molecular docking analysis of DBA and specific inhibitors of Rab proteins (Lovastatin, BFA, Zoledronate, and NE10790) indicated that DBA had optimum binding affinity with LdRab6 protein. This was further confirmed by the GTPase activity of DBA-treated LdRab6 which showed a basal GTP level significantly lower than that of the wild-type rLdRab6. The results confirm that DBA inhibits the GTPase activity of LdRab6 protein from L. donovani (LdRab6), a potential target for its antileishmanial effect.


Assuntos
Antiprotozoários/farmacologia , Inibidores Enzimáticos/farmacologia , Leishmania donovani/efeitos dos fármacos , Leishmaniose Visceral/parasitologia , Pentanonas/farmacologia , Proteínas de Protozoários/antagonistas & inibidores , Proteínas rab de Ligação ao GTP/antagonistas & inibidores , Sequência de Aminoácidos , Sítios de Ligação , Curcumina/farmacologia , Humanos , Leishmania donovani/química , Leishmania donovani/enzimologia , Leishmania donovani/genética , Leishmaniose Visceral/tratamento farmacológico , Simulação de Acoplamento Molecular , Pentanonas/química , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Alinhamento de Sequência , Proteínas rab de Ligação ao GTP/química , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
15.
PLoS One ; 15(8): e0235551, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32833964

RESUMO

VPS34 is a key regulator of endomembrane dynamics and cargo trafficking, and is essential in cultured cell lines and in mice. To better characterize the role of VPS34 in cell growth, we performed unbiased cell line profiling studies with the selective VPS34 inhibitor PIK-III and identified RKO as a VPS34-dependent cellular model. Pooled CRISPR screen in the presence of PIK-III revealed endolysosomal genes as genetic suppressors. Dissecting VPS34-dependent alterations with transcriptional profiling, we found the induction of hypoxia response and cholesterol biosynthesis as key signatures. Mechanistically, acute VPS34 inhibition enhanced lysosomal degradation of transferrin and low-density lipoprotein receptors leading to impaired iron and cholesterol uptake. Excess soluble iron, but not cholesterol, was sufficient to partially rescue the effects of VPS34 inhibition on mitochondrial respiration and cell growth, indicating that iron limitation is the primary driver of VPS34-dependency in RKO cells. Loss of RAB7A, an endolysosomal marker and top suppressor in our genetic screen, blocked transferrin receptor degradation, restored iron homeostasis and reversed the growth defect as well as metabolic alterations due to VPS34 inhibition. Altogether, our findings suggest that impaired iron mobilization via the VPS34-RAB7A axis drive VPS34-dependence in certain cancer cells.


Assuntos
Classe III de Fosfatidilinositol 3-Quinases/metabolismo , Ferro/metabolismo , Neoplasias/metabolismo , Hipóxia Celular , Linhagem Celular Tumoral , Proliferação de Células , Colesterol/biossíntese , Colesterol/genética , Classe III de Fosfatidilinositol 3-Quinases/genética , Endossomos/metabolismo , Células HEK293 , Humanos , Lisossomos/metabolismo , Receptores de LDL/metabolismo , Transferrina/metabolismo , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
16.
Arterioscler Thromb Vasc Biol ; 40(9): 2054-2069, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32640907

RESUMO

OBJECTIVE: Increased CTSS (cathepsin S) has been reported to play a critical role in atherosclerosis progression. Both CTSS synthesis and secretion are essential for exerting its functions. However, the underlying mechanisms contributing to CTSS synthesis and secretion in atherosclerosis remain unclear. Approach and Results: In this study, we showed that nicotine activated autophagy and upregulated CTSS expression in vascular smooth muscle cells and in atherosclerotic plaques. Western blotting and immunofluorescent staining showed that nicotine inhibited the mTORC1 (mammalian target of rapamycin complex 1) activity, promoted the nuclear translocation of TFEB (transcription factor EB), and upregulated the expression of CTSS. Chromatin immunoprecipitation-qualificative polymerase chain reaction, electrophoretic mobility shift assay, and luciferase reporter assay further demonstrated that TFEB directly bound to the CTSS promoter. mTORC1 inhibition by nicotine or rapamycin promoted lysosomal exocytosis and CTSS secretion. Live cell assays and IP-MS (immunoprecipitation-mass spectrometry) identified that the interactions involving Rab10 (Rab10, member RAS oncogene family) and mTORC1 control CTSS secretion. Nicotine promoted vascular smooth muscle cell migration by upregulating CTSS, and CTSS inhibition suppressed nicotine-induced atherosclerosis in vivo. CONCLUSIONS: We concluded that nicotine mediates CTSS synthesis and secretion through regulating the autophagy-lysosomal machinery, which offers a potential therapeutic target for atherosclerosis treatment.


Assuntos
Aterosclerose/tratamento farmacológico , Autofagia/efeitos dos fármacos , Catepsinas/biossíntese , Lisossomos/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Miócitos de Músculo Liso/efeitos dos fármacos , Nicotina/farmacologia , Animais , Aterosclerose/enzimologia , Aterosclerose/genética , Aterosclerose/patologia , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Catepsinas/genética , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Modelos Animais de Doenças , Exocitose , Lisossomos/enzimologia , Lisossomos/ultraestrutura , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos Knockout para ApoE , Músculo Liso Vascular/enzimologia , Músculo Liso Vascular/ultraestrutura , Miócitos de Músculo Liso/enzimologia , Miócitos de Músculo Liso/ultraestrutura , Via Secretória , Transdução de Sinais , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
17.
Nat Commun ; 11(1): 3516, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32665580

RESUMO

It is unclear whether the establishment of apical-basal cell polarity during the generation of epithelial lumens requires molecules acting at the plasma membrane/actin interface. Here, we show that the I-BAR-containing IRSp53 protein controls lumen formation and the positioning of the polarity determinants aPKC and podocalyxin. Molecularly, IRSp53 acts by regulating the localization and activity of the small GTPase RAB35, and by interacting with the actin capping protein EPS8. Using correlative light and electron microscopy, we further show that IRSp53 ensures the shape and continuity of the opposing plasma membrane of two daughter cells, leading to the formation of a single apical lumen. Genetic removal of IRSp53 results in abnormal renal tubulogenesis, with altered tubular polarity and architectural organization. Thus, IRSp53 acts as a membrane curvature-sensing platform for the assembly of multi-protein complexes that control the trafficking of apical determinants and the integrity of the luminal plasma membrane.


Assuntos
Membrana Celular/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Actinas/metabolismo , Polaridade Celular/genética , Polaridade Celular/fisiologia , Células Epiteliais/metabolismo , Feminino , Humanos , Morfogênese/genética , Morfogênese/fisiologia , Proteínas do Tecido Nervoso/genética , Transporte Proteico/genética , Transporte Proteico/fisiologia , Sialoglicoproteínas/genética , Sialoglicoproteínas/metabolismo , Proteínas rab de Ligação ao GTP/genética
18.
Nat Commun ; 11(1): 2835, 2020 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-32503983

RESUMO

Inherited peripheral neuropathies (IPNs) represent a broad group of disorders including Charcot-Marie-Tooth (CMT) neuropathies characterized by defects primarily arising in myelin, axons, or both. The molecular mechanisms by which mutations in nearly 100 identified IPN/CMT genes lead to neuropathies are poorly understood. Here we show that the Ras-related GTPase Rab35 controls myelin growth via complex formation with the myotubularin-related phosphatidylinositol (PI) 3-phosphatases MTMR13 and MTMR2, encoded by genes responsible for CMT-types 4B2 and B1 in humans, and found that it downregulates lipid-mediated mTORC1 activation, a pathway known to crucially regulate myelin biogenesis. Targeted disruption of Rab35 leads to hyperactivation of mTORC1 signaling caused by elevated levels of PI 3-phosphates and to focal hypermyelination in vivo. Pharmacological inhibition of phosphatidylinositol 3,5-bisphosphate synthesis or mTORC1 signaling ameliorates this phenotype. These findings reveal a crucial role for Rab35-regulated lipid turnover by myotubularins to repress mTORC1 activity and to control myelin growth.


Assuntos
Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Bainha de Mielina/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Animais , Astrócitos , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/patologia , Regulação para Baixo , Técnicas de Introdução de Genes , Células HEK293 , Células HeLa , Humanos , Metabolismo dos Lipídeos/genética , Camundongos Transgênicos , Mutação , Bainha de Mielina/patologia , Cultura Primária de Células , Proteínas Tirosina Fosfatases não Receptoras/antagonistas & inibidores , Proteínas Tirosina Fosfatases não Receptoras/genética , Proteínas Tirosina Fosfatases não Receptoras/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Proteínas rab de Ligação ao GTP/genética
19.
Nat Commun ; 11(1): 3017, 2020 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-32541798

RESUMO

Breast cancer brain metastases (BCBM) have a 5-20 year latency and account for 30% of mortality; however, mechanisms governing adaptation to the brain microenvironment remain poorly defined. We combine time-course RNA-sequencing of BCBM development with a Drosophila melanogaster genetic screen, and identify Rab11b as a functional mediator of metastatic adaptation. Proteomic analysis reveals that Rab11b controls the cell surface proteome, recycling proteins required for successful interaction with the microenvironment, including integrin ß1. Rab11b-mediated control of integrin ß1 surface expression allows efficient engagement with the brain ECM, activating mechanotransduction signaling to promote survival. Lipophilic statins prevent membrane association and activity of Rab11b, and we provide proof-of principle that these drugs prevent breast cancer adaptation to the brain microenvironment. Our results identify Rab11b-mediated recycling of integrin ß1 as regulating BCBM, and suggest that the recycleome, recycling-based control of the cell surface proteome, is a previously unknown driver of metastatic adaptation and outgrowth.


Assuntos
Neoplasias Encefálicas/metabolismo , Neoplasias da Mama/patologia , Integrina beta1/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Animais , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/fisiopatologia , Neoplasias Encefálicas/secundário , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Proliferação de Células , Modelos Animais de Doenças , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Feminino , Humanos , Integrina beta1/genética , Camundongos , Camundongos Endogâmicos C57BL , Metástase Neoplásica , Transporte Proteico , Transdução de Sinais , Microambiente Tumoral , Proteínas rab de Ligação ao GTP/genética
20.
Proc Natl Acad Sci U S A ; 117(25): 14532-14542, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32513733

RESUMO

Implantation is initiated when an embryo attaches to the uterine luminal epithelium and subsequently penetrates into the underlying stroma to firmly embed in the endometrium. These events are followed by the formation of an extensive vascular network in the stroma that supports embryonic growth and ensures successful implantation. Interestingly, in many mammalian species, these processes of early pregnancy occur in a hypoxic environment. However, the mechanisms underlying maternal adaptation to hypoxia during early pregnancy remain unclear. In this study, using a knockout mouse model, we show that the transcription factor hypoxia-inducible factor 2 alpha (Hif2α), which is induced in subluminal stromal cells at the time of implantation, plays a crucial role during early pregnancy. Indeed, when preimplantation endometrial stromal cells are exposed to hypoxic conditions in vitro, we observed a striking enhancement in HIF2α expression. Further studies revealed that HIF2α regulates the expression of several metabolic and protein trafficking factors, including RAB27B, at the onset of implantation. RAB27B is a member of the Rab family of GTPases that allows controlled release of secretory granules. These granules are involved in trafficking MMP-9 from the stroma to the epithelium to promote luminal epithelial remodeling during embryo invasion. As pregnancy progresses, the HIF2α-RAB27B pathway additionally mediates crosstalk between stromal and endothelial cells via VEGF granules, developing the vascular network critical for establishing pregnancy. Collectively, our study provides insights into the intercellular communication mechanisms that operate during adaptation to hypoxia, which is essential for embryo implantation and establishment of pregnancy.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Hipóxia Celular/fisiologia , Implantação do Embrião/fisiologia , Vesículas Secretórias/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Comunicação Celular/fisiologia , Linhagem Celular , Embrião de Mamíferos , Endométrio/citologia , Endométrio/metabolismo , Feminino , Técnicas de Introdução de Genes , Humanos , Masculino , Camundongos , Camundongos Knockout , Gravidez , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Transdução de Sinais/fisiologia , Células Estromais , Proteínas rab de Ligação ao GTP/genética
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