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1.
Cancer Lett ; 592: 216929, 2024 Jun 28.
Article in English | MEDLINE | ID: mdl-38697461

ABSTRACT

Small cell lung cancer (SCLC) is a recalcitrant cancer characterized by high frequency loss-of-function mutations in tumor suppressors with a lack of targeted therapy due to absence of high frequency gain-of-function abnormalities in oncogenes. SMARCAL1 is a member of the ATP-dependent chromatin remodeling protein SNF2 family that plays critical roles in DNA damage repair and genome stability maintenance. Here, we showed that SMARCAL1 was overexpressed in SCLC patient samples and was inversely associated with overall survival of the patients. SMARCAL1 was required for SCLC cell proliferation and genome integrity. Mass spectrometry revealed that PAR6B was a downstream SMARCAL1 signal molecule which rescued inhibitory effects caused by silencing of SMARCAL1. By screening of 36 FDA-approved clinically available agents related to DNA damage repair, we found that an aza-anthracenedione, pixantrone, was a potent SMARCAL1 inhibitor which suppressed the expression of SMARCAL1 and PAR6B at protein level. Pixantrone caused DNA damage and exhibited inhibitory effects on SCLC cells in vitro and in a patient-derived xenograft mouse model. These results indicated that SMARCAL1 functions as an oncogene in SCLC, and pixantrone as a SMARCAL1 inhibitor bears therapeutic potentials in this deadly disease.


Subject(s)
Cell Proliferation , DNA Helicases , Lung Neoplasms , Small Cell Lung Carcinoma , Xenograft Model Antitumor Assays , Humans , Small Cell Lung Carcinoma/drug therapy , Small Cell Lung Carcinoma/genetics , Small Cell Lung Carcinoma/pathology , Small Cell Lung Carcinoma/metabolism , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Lung Neoplasms/metabolism , Animals , DNA Helicases/genetics , DNA Helicases/metabolism , Cell Proliferation/drug effects , Mice , Cell Line, Tumor , DNA Damage , Gene Expression Regulation, Neoplastic/drug effects , DNA Repair/drug effects
2.
Cell Rep ; 42(2): 112093, 2023 02 28.
Article in English | MEDLINE | ID: mdl-36773292

ABSTRACT

Apical-basal polarity and cell-fate determinants are crucial for the cell fate and control of stem cell numbers. However, their interplay leading to a precise stem cell number remains unclear. Drosophila pupal intestinal stem cells (pISCs) asymmetrically divide, generating one apical ISC progenitor and one basal Prospero (Pros)+ enteroendocrine mother cell (EMC), followed by symmetric divisions of each daughter before adulthood, providing an ideal system to investigate the outcomes of polarity loss. Using lineage tracing and ex vivo live imaging, we identify an interlocked polarity regulation network precisely determining ISC number: Bazooka inhibits Pros accumulation by activating Notch signaling to maintain stem cell fate in pISC apical daughters. A threshold of Pros promotes differentiation to EMCs and avoids ISC-like cell fate, and over-threshold of Pros inhibits miranda expression to ensure symmetric divisions in pISC basal daughters. Our work suggests that a polarity-dependent threshold of a differentiation factor precisely controls stem cell number.


Subject(s)
Drosophila Proteins , Drosophila melanogaster , Animals , Cell Count , Cell Differentiation , Cell Polarity , Drosophila/metabolism , Drosophila melanogaster/cytology , Drosophila melanogaster/metabolism , Drosophila Proteins/metabolism , Intestines
3.
Mol Neurobiol ; 60(3): 1626-1644, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36542194

ABSTRACT

The invasion of glioblastoma usually results in the recurrence and poor prognosis in patients with glioma. However, the underlying mechanisms involved in glioma invasion remains undefined. In this study, immunohistochemistry analyses of glioma specimens demonstrated that high expression of Par6 was positively correlated with malignancy and poor prognosis of patients with glioma. Par6-overexpressing glioma cells showed much more fibroblast-like morphology, suggesting that regulation of Par6 expression might be associated with tumor invasion in glioma cells. Further study indicated that Par6 overexpression subsequently increased CD44 and N-cadherin expression to enhance glioma invasion through activating MEK/ERK/STAT3 pathway, in vivo and in vitro. Moreover, we found that LIN28/let-7d axis was involved in this process via a positive feedback loop, suggesting that MEK/ERK/LIN28/let-7d/STAT3 cascade might be essential for Par6-mediated glioma invasion. Therefore, these data highlight the roles of Par6 in glioma invasion, and Par6 may serve as a potential therapeutic target for patients with glioma.


Subject(s)
Adaptor Proteins, Signal Transducing , Glioma , MicroRNAs , Humans , Cell Line, Tumor , Cell Proliferation , Feedback , Gene Expression Regulation, Neoplastic , Glioblastoma/pathology , Glioma/pathology , MAP Kinase Signaling System , MicroRNAs/metabolism , Mitogen-Activated Protein Kinase Kinases/metabolism , Adaptor Proteins, Signal Transducing/metabolism
4.
J Neurosci ; 42(24): 4774-4793, 2022 06 15.
Article in English | MEDLINE | ID: mdl-35705493

ABSTRACT

Normal neural circuits and functions depend on proper neuronal differentiation, migration, synaptic plasticity, and maintenance. Abnormalities in these processes underlie various neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Neural development and maintenance are regulated by many proteins. Among them are Par3, Par6 (partitioning defective 3 and 6), and aPKC (atypical protein kinase C) families of evolutionarily conserved polarity proteins. These proteins perform versatile functions by forming tripartite or other combinations of protein complexes, which hereafter are collectively referred to as "Par complexes." In this review, we summarize the major findings on their biophysical and biochemical properties in cell polarization and signaling pathways. We next summarize their expression and localization in the nervous system as well as their versatile functions in various aspects of neurodevelopment, including neuroepithelial polarity, neurogenesis, neuronal migration, neurite differentiation, synaptic plasticity, and memory. These versatile functions rely on the fundamental roles of Par complexes in cell polarity in distinct cellular contexts. We also discuss how cell polarization may correlate with subcellular polarization in neurons. Finally, we review the involvement of Par complexes in neuropsychiatric and neurodegenerative disorders, such as schizophrenia and Alzheimer's disease. While emerging evidence indicates that Par complexes are essential for proper neural development and maintenance, many questions on their in vivo functions have yet to be answered. Thus, Par3, Par6, and aPKC continue to be important research topics to advance neuroscience.


Subject(s)
Cell Polarity , Protein Kinase C , Cell Cycle Proteins/metabolism , Cell Polarity/physiology , Protein Kinase C/metabolism , Proteins , Signal Transduction
5.
Mol Biotechnol ; 64(12): 1319-1327, 2022 Dec.
Article in English | MEDLINE | ID: mdl-35610404

ABSTRACT

The tripartite partition defect (PAR) polarity complex, which includes the proteins PAR3, atypical protein kinase C (aPKC), and PAR6, is a major regulator of cellular polarity. It is highly conserved and expressed in various tissues. Its largest component, PAR3, controls protein-protein interactions of the PAR complex with a variety of interaction partners, and PAR3 self-association is critical for the formation of filament-like structures. However, little is known about the structure of the PAR complex. Here, we purified non-filamentous PAR3 and the aPKC-PAR6 complex and characterized them by single-particle electron microscopy (EM). We expressed and purified an oligomerization-deficient form of PAR3, PAR3V13D,D70K, and the active aPKC-PAR6 dimer. For PAR3, engineering at two positions is sufficient to form stable single particles with a maximum dimension of 20 nm. aPKC-PAR6 forms a complex with a maximum dimension of 13.5 nm that contains single copies of aPKC. Thus, the data present a basis for further high-resolution studies of PAR proteins and PAR complex formation.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Protein Kinase C , Adaptor Proteins, Signal Transducing/chemistry , Adaptor Proteins, Signal Transducing/genetics , Cell Polarity , Humans , Protein Kinase C/genetics , Protein Kinase C/metabolism
6.
Elife ; 102021 06 17.
Article in English | MEDLINE | ID: mdl-34137371

ABSTRACT

Sustained polarity and adhesion of epithelial cells is essential for the protection of our organs and bodies, and this epithelial integrity emerges during organ development amidst numerous programmed morphogenetic assaults. Using the developing Caenorhabditis elegans intestine as an in vivo model, we investigated how epithelia maintain their integrity through cell division and elongation to build a functional tube. Live imaging revealed that apical PAR complex proteins PAR-6/Par6 and PKC-3/aPkc remained apical during mitosis while apical microtubules and microtubule-organizing center (MTOC) proteins were transiently removed. Intestine-specific depletion of PAR-6, PKC-3, and the aPkc regulator CDC-42/Cdc42 caused persistent gaps in the apical MTOC as well as in other apical and junctional proteins after cell division and in non-dividing cells that elongated. Upon hatching, gaps coincided with luminal constrictions that blocked food, and larvae arrested and died. Thus, the apical PAR complex maintains apical and junctional continuity to construct a functional intestinal tube.


Subject(s)
Caenorhabditis elegans Proteins/metabolism , Epithelial Cells , Intestinal Mucosa , Animals , Caenorhabditis elegans , Epithelial Cells/cytology , Epithelial Cells/metabolism , Intestinal Mucosa/cytology , Intestinal Mucosa/metabolism , Intestinal Mucosa/physiology , Intestines/cytology , Intestines/growth & development , Larva/growth & development , Microtubule-Organizing Center/metabolism , Protein Kinase C/metabolism
7.
Development ; 148(7)2021 04 01.
Article in English | MEDLINE | ID: mdl-33688074

ABSTRACT

Discs large (Dlg) is an essential polarity protein and a tumor suppressor originally characterized in Drosophila but also well conserved in vertebrates. Like the majority of polarity proteins, plasma membrane (PM)/cortical localization of Dlg is required for its function in polarity and tumorigenesis, but the exact mechanisms targeting Dlg to the PM remain to be fully elucidated. Here, we show that, similar to recently discovered polybasic polarity proteins such as Lgl and aPKC, Dlg also contains a positively charged polybasic domain that electrostatically binds the PM phosphoinositides PI4P and PI(4,5)P2 Electrostatic targeting by the polybasic domain contributes significantly to the PM localization of Dlg in follicular and early embryonic epithelial cells, and is crucial for Dlg to regulate both polarity and tumorigenesis. The electrostatic PM targeting of Dlg is controlled by a potential phosphorylation-dependent allosteric regulation of its polybasic domain, and is specifically enhanced by the interactions between Dlg and another basolateral polarity protein and tumor suppressor, Scrib. Our studies highlight an increasingly significant role of electrostatic PM targeting of polarity proteins in regulating cell polarity.


Subject(s)
Cell Membrane/metabolism , Drosophila Proteins/metabolism , Static Electricity , Tumor Suppressor Proteins/metabolism , Animals , Animals, Genetically Modified , Carcinogenesis/metabolism , Cell Membrane/genetics , Cell Physiological Phenomena , Cell Polarity , Drosophila/metabolism , Drosophila Proteins/genetics , Epithelial Cells/metabolism , Female , Genes, Tumor Suppressor , Male , Tumor Suppressor Proteins/genetics
8.
Front Pharmacol ; 12: 752787, 2021.
Article in English | MEDLINE | ID: mdl-35069190

ABSTRACT

Tight junctions (TJ) are formed by transmembrane and intracellular proteins that seal the intercellular space and control selective permeability of epithelia. Integrity of the epithelial barrier is central to tissue homeostasis and barrier dysfunction has been linked to many pathological conditions. TJ support the maintenance of cell polarity through interactions with the Par complex (Cdc42-Par-6-Par-3-aPKC) in which Par-6 is an adaptor and links the proteins of the complex together. Studies have shown that Par-6 overexpression delays the assembly of TJ proteins suggesting that Par-6 negatively regulates TJ assembly. Because restoring barrier integrity is of key therapeutic and prophylactic value, we focus on finding compounds that have epithelial barrier reinforcement properties; we developed a screening platform (theLiTE™) to identify compounds that modulate Par-6 expression in follicular epithelial cells from Par-6-GFP Drosophila melanogaster egg chambers. Hits identified were then tested whether they improve epithelial barrier function, using measurements of transepithelial electrical resistance (TEER) or dye efflux to evaluate paracellular permeability. We tested 2,400 compounds, found in total 10 hits. Here we present data on six of them: the first four hits allowed us to sequentially build confidence in theLiTE™ and two compounds that were shortlisted for further development (myricetin and quercetin). We selected quercetin due to its clinical and scientific validation as a compound that regulates TJ; food supplement formulated on the basis of this discovery is currently undergoing clinical evaluation in gastroesophageal reflux disease (GERD) sufferers.

9.
Elife ; 92020 12 10.
Article in English | MEDLINE | ID: mdl-33300872

ABSTRACT

The cortical polarity regulators PAR-6, PKC-3, and PAR-3 are essential for the polarization of a broad variety of cell types in multicellular animals. In C. elegans, the roles of the PAR proteins in embryonic development have been extensively studied, yet little is known about their functions during larval development. Using inducible protein degradation, we show that PAR-6 and PKC-3, but not PAR-3, are essential for postembryonic development. PAR-6 and PKC-3 are required in the epidermal epithelium for animal growth, molting, and the proper pattern of seam-cell divisions. Finally, we uncovered a novel role for PAR-6 in organizing non-centrosomal microtubule arrays in the epidermis. PAR-6 was required for the localization of the microtubule organizer NOCA-1/Ninein, and defects in a noca-1 mutant are highly similar to those caused by epidermal PAR-6 depletion. As NOCA-1 physically interacts with PAR-6, we propose that PAR-6 promotes non-centrosomal microtubule organization through localization of NOCA-1/Ninein.


Subject(s)
Caenorhabditis elegans Proteins/physiology , Caenorhabditis elegans/growth & development , Epidermis/metabolism , Microtubules/metabolism , Protein Kinase C/physiology , Animals , Caenorhabditis elegans/metabolism , Caenorhabditis elegans Proteins/metabolism , Cell Division , Larva , Protein Kinase C/metabolism
10.
Biochim Biophys Acta Biomembr ; 1862(10): 183399, 2020 10 01.
Article in English | MEDLINE | ID: mdl-32553946

ABSTRACT

Tight and adherens junctions are specialized sites of cell-cell interaction in epithelia and endothelia, and are involved in barrier, adhesion, and signaling functions. These functions are orchestrated by a highly organized meshwork of macromolecules in the membrane and cytoplasmic compartments. In this review, we discuss the structural organization and functions of the major cytoplasmic scaffolding and adaptor proteins of vertebrate apical junctions (ZO proteins, afadin, PLEKHA7, cingulin, paracingulin, polarity complex proteins, and a few others), focusing on their interactions with cytoskeletal and signaling proteins. Furthermore, we discuss recent results highlighting how mechanical tension, protein-protein interactions and post-translational modifications regulate the conformation and function of scaffolding proteins, and how spontaneous phase separation into biomolecular condensates contributes to apical junction assembly. Using a sequence-based algorithm, a large fraction of cytoplasmic proteins of apical junctions are predicted to be phase separating proteins (PSPs), suggesting that formation of biomolecular condensates is a general mechanism to organize cell-cell contacts by clustering proteins.


Subject(s)
Intercellular Junctions/metabolism , Vertebrates/metabolism , Animals , Biophysical Phenomena , Cytoplasm/metabolism , Ligands
11.
FASEB J ; 34(1): 1481-1496, 2020 01.
Article in English | MEDLINE | ID: mdl-31914615

ABSTRACT

As the key factor of the polarity protein complex, Par6 not only regulates polarization processes, but also plays important roles in tumor metastasis and progression in many epithelium malignancy tumors. Here, we showed that Par6 is an essential component in glioma tumorigenesis. Our results indicated the aberrant expression of Par6 in malignant glioma tissues and cell lines. We found that the regulation of Par6 expression induces cell proliferation and tumor growth in vivo and in vitro. Additionally, RNA-seq revealed the effects of Par6 were associated with cyclin D1-regulated cell cycle progression in glioma cells. Moreover, our results demonstrated that the regulation of Par6 can enhance the activation of Akt/PI3K signaling pathway, and subsequently upregulate the expression level of GSK-3ß protein, which then regulate cyclin D1-mediated cell cycle regulation. Furthermore, we found that TGF-ß-induced the upregulation of Par6 expression may be involved in this process. The pathological analysis confirmed the correlation between Par6 expression and the prognosis in human glioma tissues, suggesting the regulation of Par6 expression regulates glioma tumorigenesis and progression. Thus, our findings showed that Par6 might be a potential biomarker for the diagnosis and providing a therapeutic strategy for the treatment of malignant glioma.


Subject(s)
Adaptor Proteins, Signal Transducing/biosynthesis , Biomarkers, Tumor/biosynthesis , Cell Cycle , Gene Expression Regulation, Neoplastic , Glioma/metabolism , Signal Transduction , Adaptor Proteins, Signal Transducing/genetics , Animals , Biomarkers, Tumor/genetics , Cell Line, Tumor , Cyclin D1/genetics , Cyclin D1/metabolism , Glioma/genetics , Glioma/pathology , Glycogen Synthase Kinase 3 beta/genetics , Glycogen Synthase Kinase 3 beta/metabolism , Humans , Male , Mice , Mice, Nude , Phosphatidylinositol 3-Kinases/genetics , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism
12.
Development ; 146(15)2019 08 12.
Article in English | MEDLINE | ID: mdl-31405903

ABSTRACT

Cdc42 regulates epithelial morphogenesis together with the Par complex (Baz/Par3-Par6-aPKC), Crumbs (Crb/CRB3) and Stardust (Sdt/PALS1). However, how these proteins work together and interact during epithelial morphogenesis is not well understood. To address this issue, we used the genetically amenable Drosophila pupal photoreceptor and follicular epithelium. We show that during epithelial morphogenesis active Cdc42 accumulates at the developing apical membrane and cell-cell contacts, independently of the Par complex and Crb. However, membrane localization of Baz, Par6-aPKC and Crb all depend on Cdc42. We find that although binding of Cdc42 to Par6 is not essential for the recruitment of Par6 and aPKC to the membrane, it is required for their apical localization and accumulation, which we find also depends on Par6 retention by Crb. In the pupal photoreceptor, membrane recruitment of Par6-aPKC also depends on Baz. Our work shows that Cdc42 is required for this recruitment and suggests that this factor promotes the handover of Par6-aPKC from Baz onto Crb. Altogether, we propose that Cdc42 drives morphogenesis by conferring apical identity, Par-complex assembly and apical accumulation of Crb.


Subject(s)
Drosophila Proteins/metabolism , Drosophila melanogaster/growth & development , GTP-Binding Proteins/metabolism , Membrane Proteins/metabolism , Photoreceptor Cells/cytology , Protein Kinase C/metabolism , Animals , Cell Polarity/physiology , Drosophila melanogaster/metabolism , Epithelium/growth & development , Morphogenesis/physiology , Protein Binding/physiology
13.
F1000Res ; 72018.
Article in English | MEDLINE | ID: mdl-29983916

ABSTRACT

Establishing and maintaining cell polarity are dynamic processes that necessitate complicated but highly regulated protein interactions. Phosphorylation is a powerful mechanism for cells to control the function and subcellular localization of a target protein, and multiple kinases have played critical roles in cell polarity. Among them, atypical protein kinase C (aPKC) is likely the most studied kinase in cell polarity and has the largest number of downstream substrates characterized so far. More than half of the polarity proteins that are essential for regulating cell polarity have been identified as aPKC substrates. This review covers mainly studies of aPKC in regulating anterior-posterior polarity in the worm one-cell embryo and apical-basal polarity in epithelial cells and asymmetrically dividing cells (for example, Drosophila neuroblasts). We will go through aPKC target proteins in cell polarity and discuss various mechanisms by which aPKC phosphorylation controls their subcellular localizations and biological functions. We will also review the recent progress in determining the detailed molecular mechanisms in spatial and temporal control of aPKC subcellular localization and kinase activity during cell polarization.

14.
J Mol Histol ; 49(5): 449-458, 2018 Oct.
Article in English | MEDLINE | ID: mdl-29992488

ABSTRACT

The Par complex (Par-6/Par-3/aPKC) plays a key role in the maintenance of the intestinal barrier function through the regulation of epithelial junction formation. The aryl hydrocarbon receptor (AhR) has been shown to be an important regulator for intestinal homeostasis. In this study, we investigated the role of the AhR activation on the regulation of Par complex. AhR activation by 6-formylindolo (3,2-b) carbazole (FICZ) represses the abnormal expression of the Par complex in a mouse model of dextran sulphate sodium (DSS)-induced colitis. In T84 cells, overexpression of Par-6 causes intestinal barrier dysfunction. Lipopolysaccharide (LPS)-induced intestinal epithelial barrier dysfunction and increase in Par-6 expression was prevented by AhR activation. However, FICZ did not alter the expression of Par-3 or aPKC. Furthermore, AhR activation alleviated LPS-induced increase of Par-6 through repressing the expression of activating protein-2γ (Ap-2γ). These results reveal the protective effects of AhR activation on LPS induced disruption of intestinal epithelial barrier function through suppressing the expression of Par-6 expression. Our findings provide novel insights into the protective role of AhR in intestinal barrier function.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Intestinal Mucosa/physiology , Receptors, Aryl Hydrocarbon/physiology , Animals , Carbazoles/pharmacology , Cell Line , Colitis/chemically induced , Dextran Sulfate/adverse effects , Humans , Intercellular Junctions , Lipopolysaccharides , Mice , Receptors, Aryl Hydrocarbon/metabolism , Transcription Factor AP-2/metabolism
15.
FASEB J ; 32(10): 5577-5586, 2018 10.
Article in English | MEDLINE | ID: mdl-29727209

ABSTRACT

The human rhomboid family (RHBDF)1 gene is highly expressed in breast cancer under clinical conditions but not in normal mammary gland tissues. Silencing the RHBDF1 gene in breast cancer xenograft tumors leads to inhibition of tumor growth. We show in this study that artificially raising RHBDF1 protein levels in the mammary epithelial cells MCF-10A results in severe perturbations of the ability of the cells to form lumen-containing acini, either in 3-dimensional cell cultures or implanted in mouse mammary fat pads. Knocking down RHBDF1 with short hairpin (sh)RNA leads to restoration of acinus formation. Consistently, RHBDF1 overexpression gives rise to disordered distribution of polarity markers GM130 and laminin-5, which otherwise are located in apical and basal positions, respectively, in the acini. Further investigations reveal that RHBDF1 directly binds to Par6a, a component of a protein complex consisting of partitioning-defective scaffold protein (Par)6, Par3, renin-angiotensin system-related C3 botulinum toxin substrate (Rac)1, and cell-division cycle (Cdc)42, which is structurally critical to the formation of apicobasal polarity. RHBDF1 binding to Par6a results in collapse of the protein complex and thus disruption of polarity formation. Since early stages of breast cancer are characterized by the loss of mammary gland epithelial cell polarity, our findings indicate that perturbations of apicobasal polarity by high levels of RHBDF1 is a significant attribute in the development of breast neoplasia.-Peng, X.-M., Gao, S., Deng, H.-T., Cai, H.-X., Zhou, Z., Xiang, R., Zhang, Q.-Z., Li, L.-Y. Perturbation of epithelial apicobasal polarity by rhomboid family-1 gene overexpression.


Subject(s)
Breast Neoplasms/metabolism , Cell Polarity , Epithelial Cells/metabolism , Gene Expression Regulation, Neoplastic , Mammary Glands, Human/metabolism , Membrane Proteins/biosynthesis , Neoplasm Proteins/biosynthesis , Adaptor Proteins, Signal Transducing/biosynthesis , Adaptor Proteins, Signal Transducing/genetics , Autoantigens/biosynthesis , Autoantigens/genetics , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Cell Adhesion Molecules/biosynthesis , Cell Adhesion Molecules/genetics , Cell Line, Tumor , Humans , Mammary Glands, Human/pathology , Membrane Proteins/genetics , Neoplasm Proteins/genetics , Kalinin
16.
Biochem Biophys Res Commun ; 495(1): 1476-1481, 2018 01 01.
Article in English | MEDLINE | ID: mdl-29155179

ABSTRACT

Par6α (partitioning defective 6 homologue alpha), a component of the Par3/Par6/aPKC complex, was recently shown to be essential for axon specification during neuronal development. However, the biological functions and regulatory mechanisms of Par6α in the mesenchymal stem cell (MSC) differentiation process have not been investigated. In this study, we found that the expression of let-7f-5p was downregulated during differentiation of bone marrow-derived MSCs to neuron-like cells. Interestingly, Par6α was predicted to be a target gene of let-7f-5p by computerized analysis and the luciferase reporter assay. Using gain- and loss-of-function approaches, we found that expression of Par6α was inversely correlated with let-7f-5p levels during differentiation (p < 0.05). By silencing Par6α using siRNAs, we demonstrated that Par6α was necessary for MSC neuronal differentiation. Altogether, our studies proved that inhibition of let-7f-5p facilitates induction of MSCs into neuron-like cells by directly targeting Par6α.


Subject(s)
Carrier Proteins/metabolism , Cell Differentiation/physiology , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/physiology , MicroRNAs/metabolism , Neurons/cytology , Neurons/physiology , Adaptor Proteins, Signal Transducing , Animals , Cells, Cultured , Gene Expression Regulation, Developmental/physiology , Neurogenesis/physiology , Rats , Rats, Sprague-Dawley
17.
Dev Cell ; 42(4): 400-415.e9, 2017 08 21.
Article in English | MEDLINE | ID: mdl-28781174

ABSTRACT

The conserved polarity effector proteins PAR-3, PAR-6, CDC-42, and atypical protein kinase C (aPKC) form a core unit of the PAR protein network, which plays a central role in polarizing a broad range of animal cell types. To functionally polarize cells, these proteins must activate aPKC within a spatially defined membrane domain on one side of the cell in response to symmetry-breaking cues. Using the Caenorhabditis elegans zygote as a model, we find that the localization and activation of aPKC involve distinct, specialized aPKC-containing assemblies: a PAR-3-dependent assembly that responds to polarity cues and promotes efficient segregation of aPKC toward the anterior but holds aPKC in an inactive state, and a CDC-42-dependent assembly in which aPKC is active but poorly segregated. Cycling of aPKC between these distinct functional assemblies, which appears to depend on aPKC activity, effectively links cue-sensing and effector roles within the PAR network to ensure robust establishment of polarity.


Subject(s)
Caenorhabditis elegans Proteins/metabolism , Cell Polarity , Cyclic AMP-Dependent Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , Animals , Caenorhabditis elegans/embryology , Caenorhabditis elegans/genetics , Caenorhabditis elegans/metabolism , Caenorhabditis elegans Proteins/genetics , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cyclic AMP-Dependent Protein Kinases/genetics , GTP-Binding Proteins/genetics , GTP-Binding Proteins/metabolism , HEK293 Cells , Humans , Protein Binding , Protein Serine-Threonine Kinases/genetics , Zygote/metabolism
18.
R Soc Open Sci ; 3(11): 160776, 2016 Nov.
Article in English | MEDLINE | ID: mdl-28018665

ABSTRACT

In Drosophila, the adaptor protein Stardust is essential for the stabilization of the polarity determinant Crumbs in various epithelial tissues, including the embryonic epidermis, the follicular epithelium and photoreceptor cells of the compound eye. In turn, Stardust recruits another adaptor protein, PATJ, to the subapical region to support adherens junction formation and morphogenetic events. Moreover, Stardust binds to Lin-7, which is dispensable in epithelial cells but functions in postsynaptic vesicle fusion. Finally, Stardust has been reported to bind directly to PAR-6, thereby linking the Crumbs-Stardust-PATJ complex to the PAR-6/aPKC complex. PAR-6 and aPKC are also capable of directly binding Bazooka (the Drosophila homologue of PAR-3) to form the PAR/aPKC complex, which is essential for apical-basal polarity and cell-cell contact formation in most epithelia. However, little is known about the physiological relevance of these interactions in the embryonic epidermis of Drosophila in vivo. Thus, we performed a structure-function analysis of the annotated domains with GFP-tagged Stardust and evaluated the localization and function of the mutant proteins in epithelial cells of the embryonic epidermis. The data presented here confirm a crucial role of the PDZ domain in binding Crumbs and recruiting the protein to the subapical region. However, the isolated PDZ domain is not capable of being recruited to the cortex, and the SH3 domain is essential to support the binding to Crumbs. Notably, the conserved N-terminal regions (ECR1 and ECR2) are not crucial for epithelial polarity. Finally, the GUK domain plays an important role for the protein's function, which is not directly linked to Crumbs stabilization, and the L27N domain is essential for epithelial polarization independently of recruiting PATJ.

19.
Rev. chil. pediatr ; 87(5): 395-400, oct. 2016. ilus, tab
Article in Spanish | LILACS | ID: biblio-830169

ABSTRACT

La deleción de la región cromosómica 1p36 es una de las anomalías subteloméricas más frecuentes y causa rasgos dismórficos distintivos. Por otro lado, la trisomía distal del brazo corto del cromosoma 6 es una anormalidad cromosómica poco frecuente de fenotipo variable. Objetivo: Presentar el caso de un paciente con ambas alteraciones cromosómicas, y resaltar la vigencia e importancia del cariotipo como herramienta diagnóstica en dismorfología. Caso clínico: Lactante de 2 meses de edad con múltiples anomalías craneofaciales, hemangioma en la nuca, fosita sacra, acortamiento rizomélico, pies y manos pequeños, criptorquidia unilateral izquierda e hipotonía. Además, antecedente de restricción del crecimiento intrauterino. Producto del octavo embarazo de una mujer G8A7C1 de 28 años. Con estos hallazgos inespecíficos en el fenotipo se solicitó cariotipo que mostró una deleción parcial de 1p36.1 y una trisomía parcial de cromosoma 6p. Conclusión: El cariotipo convencional sigue siendo una herramienta importante para el etiológico en pacientes con anomalías congénitas (múltiples), mostrando en este caso una deleción parcial de 1p36.1 y una trisomía parcial de cromosoma 6p, alteraciones cromosómicas estructurales.


The deletion of chromosomal region 1p36 is one of the most common sub-telomeric microdeletion syndromes and has distinctive dysmorphic features. On the other hand, partial trisomy of the short arm of chromosome 6 is a rare chromosomal abnormality with a variable phenotype. Objective: To report a case with both chromosome abnormalities, and to highlight the importance of the karyotype as a diagnostic tool in dysmorphology. Clinical case: The case of is presented of a two month-old infant with several craniofacial anomalies, neck haemangioma, sacral pit, rhizomelic shortening, small hands and feet, left unilateral cryptorchidism, and hypotonia. The infant also suffered intrauterine growth restriction and is the product of the eighth pregnancy of a 28 years old woman. Due to the unspecific findings in phenotype, a karyotype was requested, which showed a partial deletion of 1p36.1 and a partial trisomy of chromosome 6. Conclusion: The development of new techniques in molecular biology has improved diagnostic possibilities in medical genetics. However, the traditional karyotype remains as an important diagnostic tool in patients with multiple congenital anomalies.


Subject(s)
Humans , Male , Female , Pregnancy , Infant , Adult , Trisomy/diagnosis , Abnormalities, Multiple/genetics , Karyotyping/methods , Phenotype , Abnormalities, Multiple/physiopathology , Chromosomes, Human, Pair 6 , Chromosome Deletion , Fetal Growth Retardation/genetics
20.
Rev Chil Pediatr ; 87(5): 395-400, 2016.
Article in Spanish | MEDLINE | ID: mdl-27262749

ABSTRACT

The deletion of chromosomal region 1p36 is one of the most common sub-telomeric microdeletion syndromes and has distinctive dysmorphic features. On the other hand, partial trisomy of the short arm of chromosome 6 is a rare chromosomal abnormality with a variable phenotype. OBJECTIVE: To report a case with both chromosome abnormalities, and to highlight the importance of the karyotype as a diagnostic tool in dysmorphology. CLINICAL CASE: The case of is presented of a two month-old infant with several craniofacial anomalies, neck haemangioma, sacral pit, rhizomelic shortening, small hands and feet, left unilateral cryptorchidism, and hypotonia. The infant also suffered intrauterine growth restriction and is the product of the eighth pregnancy of a 28 years old woman. Due to the unspecific findings in phenotype, a karyotype was requested, which showed a partial deletion of 1p36.1 and a partial trisomy of chromosome 6. CONCLUSION: The development of new techniques in molecular biology has improved diagnostic possibilities in medical genetics. However, the traditional karyotype remains as an important diagnostic tool in patients with multiple congenital anomalies.


Subject(s)
Abnormalities, Multiple/genetics , Karyotyping/methods , Trisomy/diagnosis , Abnormalities, Multiple/physiopathology , Adult , Chromosome Deletion , Chromosomes, Human, Pair 6 , Female , Fetal Growth Retardation/genetics , Humans , Infant , Male , Phenotype , Pregnancy
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