POSITIONAL CLONING OF THE MEN1 GENE

MEN1 基因的定位克隆

• 批准号: 7968837
• 负责人: settara chandrasekharappa
• 金额: $ 54.4万
• 依托单位: NATIONAL HUMAN GENOME RESEARCH INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7968837
• 关键词: 2q37; Affect; Amino Acid Sequence; Amino Acids; Anterior Pituitary Gland; Autistic Disorder; Biological Process; Breast; Breast Cancer Model; Cell Adhesion Molecules; Cell Nucleus; Cells; Cellular biology; Characteristics; Chondroitin Sulfate Proteoglycan; Clinical; Colon Carcinoma; Cytokeratin; DNA Damage; Defect; Development; Developmental Delay Disorders; Disease; Embryo; Endocrine; Endoderm; Enzymes; Evaluation; Exhibits; Family; Fanconi' s Anemia; Gene Mutation; Genes; Genomics; Genotoxic Stress; Germ-Line Mutation; Hand; Head and Neck Cancer; Heart; Hematologic Neoplasms; Hematopoietic; Hereditary Malignant Neoplasm; Homologous Gene; Human; Inherited; Knockout Mice; Laboratories; Lead; Malignant Neoplasms; Malignant neoplasm of pancreas; Maps; Mediating; Membrane Proteins; Menin; Modeling; Modification; Molecular; Multiple Endocrine Neoplasia Type 1; Mus; Muscle hypotonia; Mutation; Myeloid-Lymphoid Leukemia Protein; Obesity; Organogenesis; Pancreas; Pancytopenia; Parathyroid gland; Pathway interactions; Patients; Phenotype; Phenylalanine-Specific tRNA; Phosphotransferases; Predisposition; Proteins; Resistance; Resolution; Role; Small Interfering RNA; Somatic Cell; Staging; Syndrome; TP53 gene; Techniques; Technology; Tight Junctions; Tissues; Transcriptional Regulation; Tretinoin; Tube; Vascular Endothelial Cell; Yeasts; angiogenesis; base; biological adaptation to stress; cardiogenesis; claudin-1 protein; density; embryonic stem cell; enzyme activity; extracellular; fibulin 2; interstitial; mRNA Decay; malignant breast neoplasm; member; migration; overexpression; periostin; protein complex; response; small hairpin RNA; stem; tumor; tumorigenesis; versican; wybutosine

Our laboratory employs genomic technologies for identifying disease genes. We identified the gene (MEN1) responsible for multiple endocrine neoplasia type 1 (MEN1) syndrome in 1997. MEN1 is a familial cancer syndrome characterized by tumors in multiple endocrine tissues, primarily of the parathyroid, pancreas, and anterior pituitary. The amino acid sequence of the MEN1-encoded protein (menin) does not reveal any identifiable structural or functional motifs. We have developed mouse Men1+/- models displaying a tumor spectrum similar to that in humans, and thus allowing us to study the role of menin in tumorigenesis. Interestingly, homozygous loss of menin results in early embryonic lethality in mice illustrating the requirement of menin in early development and differentiation. We have found that menin resides primarily in the nucleus, and is involved in transcriptional regulation. Our efforts are focused on exploring the role(s) of menin in differentiation, organogenesis, and development and correlating this with the overall changes in expression associated with the loss or overexpression of menin. Menin-null MEF (mouse embryo fibroblst) cells showed a significant decrease in the expression of several extracellular matrix/cell adhesion protein genes including fibulin-2 (Fbln2), periostin (Postn), and versican (Cspg2, chondroitin sulfate proteoglycan). All three of these proteins, which showed reduced expression in the absence of menin, are critical for the developing heart, and thus explain the defective heart development observed in mouse embryos with the homozygous loss of menin. Menin interacts with MLL, the mixed lineage leukemia protein, and both are components of a COMPASS-like protein complex, regulating expression of Hox genes among others. MLL-null mouse embryonic stem (ES) cells are defective hematopoietic differentiation via dysregulation of Hox genes. We generated three menin-null ES clones, and found that they were deficient in their ability to generate mature hematopoietic colonies. Re-expression of either Men1 or Hoxa9 could rescue the defect. Global expression changes in menin-null ES cells during different stages of hematopoietic differentiation are being studied to evaluate the molecular changes mediated by menin in this differentiation of mesodermal lineages. We also evaluated whether loss of menin affects differentiation into endodermal lineages, using the pluripotent mouse P19 embryonic stem cells, with normal and reduced (shRNA-mediated) menin expression. Retinoic acid (RA) induces endodermal differentiation in P19 cells. However, cells with reduced menin expression were resistant to endodermal differentiation when stimulated with RA. On the other hand, menin overexpressing cells displayed characteristic endodermal phenotype by the acquisition of cytokeratin Endo A expression, a marker for the primitive endoderm. The P19 cells with reduced menin expression exhibited severe alteration in expression of several Hox genes and whether this contributes to the observed differences in differentiation needs to be studied. We have now discovered that loss of menin, mediated by siRNA, resulted in enhanced migration, and increased tube formation in HuVEC (human vascular endothelial cells), an indication of increased angiogenesis. We find increased expression of claudin-1, a tight junction membrane protein, in Men1 siRNA treated HuVECs, and this appears to mediate the increased angiogensis. We have used high-density SNP arrays to define the precise deletion boundaries in 2q37 deletion syndrome patients, characterized by several distinct physical features, and in some cases, developmental delay, obesity, hypotonia, and autism. We found the smallest deletion (<2 Mb) in a patient with minimal clinical characteristics, three cases (out of ten) where the 2q terminal deletion is also associated with duplication of the adjacent region, and a case with an interstitial deletion but intact telomeric region. A detailed evaluation of the deletion breakpoints is being pursued. We had identified amplification and overexpression of TRMT12 in breast cancer. TRMT12 is a human homolog of a yeast gene encoding an enzyme that catalyzes a step in the posttranscriptional modification of a G to a highly modified base, yW (wybutosine), present in tRNAPhe. We find that human TRMT12 can substitute for the homologous yeast gene in the yW biosynthetic pathway in yeast, and now identify the specific amino acids that are responsible for the enzyme activity. However, yW modification was unaffected in tRNAPhe from mouse mammary tumor model overexpressing TRMT12. We find that TRMT12 regulates the protein levels of SMG-1, a new member of the well-known PIKK kinase family. SMG-1 regulates non-sense mediated mRNA decay (NMD) as well as a key player in p53 mediated genotoxic stress response. The functional role(s) of TRMT12 in NMD and cellular response to DNA damage is being pursued. Fanconi anemia (FA), a recessive disorder invariably leading to bone marrow failure, also displays to some extent, hematologic malignancies and head and neck cancer. Biallelic inactivation of one of the 13 genes result in FA. Interestingly, inherited heterozygous mutations in four of these genes are known to increase susceptibility to breast or pancreatic cancer. We have initiated efforts to study the display of cancers associated with FA, and also the involvement of the FA genes in other cancers.

我们的实验室采用基因组技术来识别疾病基因。我们于1997年确定了多发性内分泌肿瘤1型综合征的基因（MEN1）。MEN1是一种以多发内分泌组织肿瘤为特征的家族性癌症综合征，主要发生在甲状旁腺、胰腺和垂体前叶。men1编码蛋白（menin）的氨基酸序列不显示任何可识别的结构或功能基序。我们已经开发出小鼠Men1+/-模型，显示出与人类相似的肿瘤谱，从而使我们能够研究menin在肿瘤发生中的作用。有趣的是，menin的纯合缺失导致小鼠早期胚胎死亡，说明menin在早期发育和分化中是必需的。我们发现menin主要存在于细胞核中，并参与转录调控。我们的工作重点是探索menin在分化、器官发生和发育中的作用，并将其与menin缺失或过表达相关的表达整体变化联系起来。