Mammalian cells are frequently at risk of DNA damage from both endogenous and exogenous sources. Accordingly, cells have evolved the DNA damage response (DDR) pathways to monitor and assure the integrity of their genome. In cells, the intact and effective DDR is essential for the maintenance of genomic stability and it acts as a critical barrier to suppress the development of cancer in humans. Two central kinases for the DDR pathway are ATM and ATR, which can phosphorylate and activate many downstream proteins for cell cycle arrest, DNA repair, or apoptosis if the damages are irreparable. In the last several years, we and others have made significant progress to this field by identifying BRIT1 (also known as MCPH1) as a novel key regulator in the DDR pathway. BRIT1 protein contains 3 breast cancer carboxyl terminal (BRCT) domains which are conserved in BRCA1, MDC1, 53BP1, and other important molecules involved in DNA damage signaling, DNA repair, and tumor suppression. Our in vitro studies revealed BRIT1 to be a chromatin-binding protein required for recruitment of many important DDR proteins (ATM, MDC1, NBS1, RAD51, BRCA2) to the DNA damage sites. We recently also generated the BRIT1 knockout mice and demonstrated its essential roles in homologous recombination DNA repair and in maintaining genomic stability in vivo. In humans, BRIT1 is located on chromosome 8p23.1, where loss of hetero-zigosity is very common in many types of cancer. In this review, we will summarize the novel roles of BRIT1 in DDR, describe the relationship of BRIT1 deficiency with cancer development, and also discuss the use of synthetic lethality approach to target cancers with HR defects due to BRIT1 deficiency.
Animals ; Chromosomal Proteins, Non-Histone/genetics/metabolism/*physiology ; DNA Damage/genetics/*physiology ; DNA Repair/genetics/*physiology ; Humans ; Mice ; Models, Biological ; Neoplasms/*genetics ; Nerve Tissue Proteins/genetics/metabolism/*physiology

Mammalian cells are frequently at risk of DNA damage from both endogenous and exogenous sources. Accordingly, cells have evolved the DNA damage response (DDR) pathways to monitor and assure the integrity of their genome. In cells, the intact and effective DDR is essential for the maintenance of genomic stability and it acts as a critical barrier to suppress the development of cancer in humans. Two central kinases for the DDR pathway are ATM and ATR, which can phosphorylate and activate many downstream proteins for cell cycle arrest, DNA repair, or apoptosis if the damages are irreparable. In the last several years, we and others have made significant progress to this field by identifying BRIT1 (also known as MCPH1) as a novel key regulator in the DDR pathway. BRIT1 protein contains 3 breast cancer carboxyl terminal (BRCT) domains which are conserved in BRCA1, MDC1, 53BP1, and other important molecules involved in DNA damage signaling, DNA repair, and tumor suppression. Our in vitro studies revealed BRIT1 to be a chromatin-binding protein required for recruitment of many important DDR proteins (ATM, MDC1, NBS1, RAD51, BRCA2) to the DNA damage sites. We recently also generated the BRIT1 knockout mice and demonstrated its essential roles in homologous recombination DNA repair and in maintaining genomic stability in vivo. In humans, BRIT1 is located on chromosome 8p23.1, where loss of hetero-zigosity is very common in many types of cancer. In this review, we will summarize the novel roles of BRIT1 in DDR, describe the relationship of BRIT1 deficiency with cancer development, and also discuss the use of synthetic lethality approach to target cancers with HR defects due to BRIT1 deficiency.
Animals ; Chromosomal Proteins, Non-Histone/genetics/metabolism/*physiology ; DNA Damage/genetics/*physiology ; DNA Repair/genetics/*physiology ; Humans ; Mice ; Models, Biological ; Neoplasms/*genetics ; Nerve Tissue Proteins/genetics/metabolism/*physiology

Enterovirus 71 (EV71) is a neurotropic pathogen that can induce hand, foot and mouth disease in children. There is an appreciable mortality rate after EV71 infections. The mechanism of action of EV71 replication is not known. Recent work has identified some of cell factors of the host that participate in the synthesis of the RNA and proteins of EV71 (e.g., hnRNP K, reticulon 3 (RTN 3)). In that work, researchers used a competitive assay to show that hnRNP K can interact with EV71 5' UTR, which is required for efficient synthesis of viral RNA. Using a yeast two-hybrid system, other researchers demonstrated that RTN 3 interacts with the N-terminal domain of EV71 2C, which is crucial for replication of viral RNA. Here, we discuss recent work focusing on the molecular mechanisms of hnRNP K and RTN 3 in the synthesis of the RNA and proteins of EV71.
Animals ; Carrier Proteins ; genetics ; metabolism ; Enterovirus A, Human ; genetics ; physiology ; Enterovirus Infections ; genetics ; metabolism ; virology ; Heterogeneous-Nuclear Ribonucleoprotein K ; Host-Pathogen Interactions ; Humans ; Membrane Proteins ; genetics ; metabolism ; Nerve Tissue Proteins ; genetics ; metabolism ; Ribonucleoproteins ; genetics ; metabolism ; Viral Proteins ; genetics ; metabolism ; Virus Replication

BACKGROUNDBrain acid soluble protein 1 (BASP1) is identified as a novel potential tumor suppressor in several cancers. However, its role in thyroid cancer has not been investigated yet. In the present study, the antitumor activities of BASP1 against the growth and migration of thyroid cancer cells were evaluated.

METHODSBASP1 expression in thyroid cancer tissues and normal tissues were examined by immunohistochemical staining and the association between its expression and prognosis was analyzed. pcDNA-BASP1 carrying full length of BASP1 cDNA was constructed to restore the expression of BASP1 in thyroid cancer cell lines (BHT-101 and KMH-2). The cell proliferation in vitro and in vivo was evaluated by WST-1 assay and xenograft tumor models, respectively. Cell cycle distribution after transfection was analyzed using flow cytometry. Cell apoptosis after transfection was examined by annexin V/propidium iodide assay. The migration was examined using transwell assay.

RESULTSBASP1 expression was abundant in normal tissues while it is significantly decreased in cancer tissues (P = 0.000). pcDNA-BASP1 restored the expression of BASP1 and significantly inhibited the growth of BHT-101 and KMH-2 cells as well as xenograft tumors in nude mice (P = 0.000). pcDNA-BASP1 induced G1 arrest and apoptosis in BHT-101 and KMH-2 cells. In addition, pcDNA-BASP1 significantly inhibited the cell migration.

CONCLUSIONSDownregulation of BASP1 expression may play a role in the tumorigenesis of thyroid cancer. Restoration of BASP1 expression exerted extensive antitumor activities against growth and migration of thyroid cancer cells, which suggested that BASP1 gene might act as a potential therapeutic agent for the treatment of thyroid cancer.

Aged ; Animals ; Apoptosis ; genetics ; physiology ; Calmodulin-Binding Proteins ; genetics ; metabolism ; Cell Cycle ; genetics ; physiology ; Cell Line, Tumor ; Cell Movement ; genetics ; physiology ; Cell Proliferation ; genetics ; physiology ; Cytoskeletal Proteins ; genetics ; metabolism ; Female ; Gene Expression Regulation, Neoplastic ; genetics ; physiology ; Humans ; Male ; Membrane Proteins ; genetics ; metabolism ; Mice ; Mice, Nude ; Middle Aged ; Nerve Tissue Proteins ; genetics ; metabolism ; Repressor Proteins ; genetics ; metabolism ; Thyroid Neoplasms ; metabolism ; pathology ; Xenograft Model Antitumor Assays

The axon guidance molecule Slit is a secreted glucoprotein which is conserved during evolution. Slit has been implicated in regulating a variety of life activities, such as axon guidance, neuronal migration, neuronal morphological differentiation, tumor metastasis, angiogenesis and heart morphogenesis. Slit function mainly depends on the binding of its LRR-2 domain to the Ig1 domain of Roundabout (Robo) receptor, meanwhile Slit function is also mediated by a range of signaling molecules, including the heparan sulfate proteoglycans (HSPGs), GTPase-activating proteins (GAPs), tyrosine kinase Abelson, calcium ions, MicroRNA-218 and other axon guidance molecules. Several transcription factors, including Single-minded, Irx and Midline, were shown to regulate slit expression. In addition, multiple Slit isoforms exist as a consequence of alternative spliced transcripts. The research on guidance mechanism of Slit will facilitate the understanding of molecular mechanism underlying neural networks formation in the process of neural development and regeneration. Meanwhile, the studying of Slit guidance mechanism could promote the prevention and treatment of human neurological diseases and cancer metastasis.
Animals ; Axons ; metabolism ; physiology ; Cell Movement ; physiology ; Drosophila Proteins ; physiology ; Gene Expression Regulation ; Humans ; Intercellular Signaling Peptides and Proteins ; genetics ; physiology ; Nerve Tissue Proteins ; genetics ; metabolism ; physiology ; Neurons ; cytology ; Receptors, Immunologic ; metabolism

Animals ; Globins ; analysis ; chemistry ; genetics ; physiology ; Humans ; Hypoxia-Ischemia, Brain ; metabolism ; prevention & control ; Nerve Tissue Proteins ; analysis ; chemistry ; genetics ; physiology ; Signal Transduction

Binding of clathrin assembly protein to clathrin triskelia induces their assembly into clathrin-coated vesicle (CCV) in neurons. The clathrin assembly protein gene (rCALM) was cloned from rat brain cDNA library. rCALM deduced 69 kD molecule has overall 73% amino acid homology compared with that of AP180 protein. The N-terminal domain, where amino acid sequences are very similar with AP180, harbours binding sites for clathrin and inositides, as well as possible phosphorylation sites, but the proline rich C-terminal domain is different from that of AP180. The mRNA expression of rCALM and AP180 by in situ hybridization histochemistry revealed that the rCALM mRNA was more intensely expressed than that of AP180, and the distribution patterns were different from each other. These results suggest that the rCALM mediates the assembly of clathrin in neural and supporting cells of brain, and regulates the clathrin coated-vesicle formation through phosphorylation and inositide metabolism. Copyright 2000 Academic Press.
Age Factors ; Alternative Splicing ; Amino Acid Sequence ; Animal ; Base Sequence ; Brain/physiology* ; Cloning, Molecular ; Gene Expression Regulation, Developmental ; Molecular Sequence Data ; Nerve Tissue Proteins/metabolism ; Nerve Tissue Proteins/genetics* ; Phosphoproteins/metabolism ; Phosphoproteins/genetics* ; Rats ; Sequence Homology, Amino Acid

Animals ; Animals, Newborn ; Electrophysiology ; Female ; Membrane Potentials ; physiology ; NAV1.3 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins ; genetics ; physiology ; Oocytes ; metabolism ; physiology ; Protein Subunits ; genetics ; physiology ; Rats ; Rats, Sprague-Dawley ; Sodium Channels ; genetics ; physiology ; Xenopus

OBJECTIVE: To explore the effect of LRRC4, a glioma suppressive gene, on blocking U251 cells in G0/G1 by MAPK signaling pathway. METHODS: LRRC4 was transfected into U251 cells, and at 24 hour of post-transfection, cells were split at a 1:3 dilution, challenged with 500 microg /mL G418 and formed a stable transfected clone pool. RT-PCR, Northern blot and Western blot were used to identify the stable transfectants. ERK, JNK and P38 expression changes were analyzed by Western blot. FACS analysis, Luciferase reporter gene assay and Western blot were used to detect the cell cycle and cyclin D1. RESULTS: LRRC4 down-regulated the expression of phosphorylated ERK2 and up-regulated the expression of total protein JNK2 (a key molecule of MAPK signaling pathway) and phosphorylated c-Jun. LRRC4 decreased the expression of mutation P53, cyclin D1 activation and its expression. U251 cells were blocked in G0/G1 by LRRC4. CONCLUSION LRRC4 can decrease JNK2, up-regulate the phosphoralated c-Jun, down-regulate mutant P53 and cyclin D1, and therefore block U251 cells in G0/G1.
Blotting, Northern ; Blotting, Western ; Cell Line, Tumor ; Cyclin D1 ; metabolism ; Flow Cytometry ; G1 Phase ; genetics ; physiology ; Glioma ; genetics ; metabolism ; pathology ; Humans ; Luciferases ; genetics ; metabolism ; MAP Kinase Signaling System ; genetics ; physiology ; Mitogen-Activated Protein Kinase Kinases ; metabolism ; Nerve Tissue Proteins ; genetics ; metabolism ; physiology ; RNA, Messenger ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; genetics ; metabolism ; Resting Phase, Cell Cycle ; genetics ; physiology ; Reverse Transcriptase Polymerase Chain Reaction ; Transfection

A previous study has indicated that Krüppel-like factor 7 (KLF7), a transcription factor that stimulates Schwann cell (SC) proliferation and axonal regeneration after peripheral nerve injury, is a promising therapeutic transcription factor in nerve injury. We aimed to identify whether inhibition of microRNA-146b (miR-146b) affected SC proliferation, migration, and myelinated axon regeneration following sciatic nerve injury by regulating its direct target KLF7. SCs were transfected with miRNA lentivirus, miRNA inhibitor lentivirus, or KLF7 siRNA lentivirus in vitro. The expression of miR146b and KLF7, as well as SC proliferation and migration, were subsequently evaluated. In vivo, an acellular nerve allograft (ANA) followed by injection of GFP control vector or a lentiviral vector encoding an miR-146b inhibitor was used to assess the repair potential in a model of sciatic nerve gap. miR-146b directly targeted KLF7 by binding to the 3'-UTR, suppressing KLF7. Up-regulation of miR-146b and KLF7 knockdown significantly reduced the proliferation and migration of SCs, whereas silencing miR-146b resulted in increased proliferation and migration. KLF7 protein was localized in SCs in which miR-146b was expressed in vivo. Similarly, 4 weeks after the ANA, anti-miR-146b increased KLF7 and its target gene nerve growth factor cascade, promoting axonal outgrowth. Closer analysis revealed improved nerve conduction and sciatic function index score, and enhanced expression of neurofilaments, P0 (anti-peripheral myelin), and myelinated axon regeneration. Our findings provide new insight into the regulation of KLF7 by miR-146b during peripheral nerve regeneration and suggest a potential therapeutic strategy for peripheral nerve injury.
Animals ; Cell Movement ; genetics ; Cell Proliferation ; genetics ; Disease Models, Animal ; Female ; Ganglia, Spinal ; cytology ; Gene Expression Regulation ; genetics ; physiology ; HEK293 Cells ; Humans ; Kruppel-Like Transcription Factors ; genetics ; metabolism ; Male ; MicroRNAs ; genetics ; metabolism ; Motor Endplate ; genetics ; Myelin P0 Protein ; metabolism ; Nerve Regeneration ; genetics ; physiology ; Nerve Tissue Proteins ; metabolism ; RNA, Small Interfering ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar ; Sciatic Neuropathy ; metabolism ; surgery ; therapy