title: Cloning and characterization of Hepp, a novel gene expressed preferentially in hematopoietic progenitors and mature blood cells.
abstract: Through differential screening of mouse hematopoietic stem cell (HSC) and progenitor-subtracted cDNA libraries we have identified a progenitor cell-specific transcript that represents a novel gene, named Hepp (hematopoietic progenitor protein). The mouse Hepp gene encodes a protein of 237 amino acids with no detectable known functional domains or motifs. Lack of invertebrate orthologs and a high degree of evolutionary conservation of the peptide sequence in vertebrate species (zebrafish, mouse, human) suggest that the Hepp gene could have conserved although as yet unknown function in vertebrates. Mouse Hepp shows a restricted expression pattern in adult tissues and is transcribed at a very low level in heart, lung, spleen, and thymus and at a higher level in muscle. During embryonic hematopoiesis Hepp is not expressed in mouse fetal liver HSC (Sca-1(+)c-kit(+)AA4.1(+)Lin(-) cells), but is abundantly transcribed in the population of hematopoietic progenitors (AA4.1(-) cells). Similarly, during adult hematopoiesis Hepp is not transcribed in the highly enriched population of bone marrow HSC (Rh-123(low)Sca-1(+)c-kit(+)Lin(-) cells), but its expression is upregulated as a greater heterogeneous population of bone marrow HSC (Lin(-)Sca-1(+) cells) differentiates into progenitors (Lin(-)Sca-1(-) cells) and more mature lymphoid and myeloid cell types. A restricted pattern of expression in adult tissues and preferential expression in both fetal and adult hematopoietic progenitors and mature blood cells suggest that Hepp could be involved in molecular regulation of HSC and progenitor cell lineage commitment and differentiation.
authors.affiliation: Department of Microbiology and Immunology, University of Miami School of Medicine, 1600 NW 10th Avenue, Miami, FL 33136, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Abdullah
authors.forename: X
authors.initials: X
authors.lastname: Jing
authors.forename: D S
authors.initials: DS
authors.lastname: Spassov
authors.forename: R G
authors.initials: RG
authors.lastname: Nachtman
authors.forename: R
authors.initials: R
authors.lastname: Jurecic
mesh_terms: D000818:Animals; D001483:Base Sequence; D001773:Blood Cells / Q000378:metabolism*; D001853:Bone Marrow / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D005796:Genes / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014018:Tissue Distribution
chemical_list: C515965:CDCA4 protein, human; C445240:Cdca4 protein, mouse; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D009124:Muscle Proteins; D012333:RNA, Messenger