Cloning, expression and localization of human BM88 shows that it maps to chromosome 11p15.5, a region implicated in Beckwith–Wiedemann syndrome and tumorigenesis

Abstract

Porcine BM88 is a neuron-specific protein that enhances neuroblastoma cell differentiation in vitro and may be involved in neuronal differentiation in vivo. Here we report the identification, by Western blotting, of homologous proteins in human and mouse brain and the isolation of their respective cDNAs. Several human and mouse clones were identified in the EST database using porcine BM88 cDNA as a query. A human and a mouse EST clone were chosen for sequencing and were found both to predict a protein of 149 amino acids, with 79.9% reciprocal identity, and 76.4% and 70.7% identities to the porcine protein, respectively. This indicated that the clones corresponded to the human and mouse BM88homologues. In vitro expression in a cell-free system as well as transient expression in COS7 cells yielded polypeptide products that were recognized by anti-BM88 antibodies and were identical in size to the native BM88 protein. Northern-blot analysis showed a wide distribution of the gene in human brain whereas immunohistochemistry on human brain sections demonstrated that the expression of BM88 is confined to neurons. The initial mapping assignment of human BM88 to chromosome 11p15.5, a region implicated in Beckwith–Wiedemann syndrome and tumorigenesis, was retrieved from the UniGene database maintained at the National Centre for Biotechnology Information (NCBI, Bethesda, MD, U.S.A.). We confirmed this localization by performing fluorescence in situ hybridization on BM88-positive cosmid clones isolated from a human genomic library. These results suggest that BM88 may be a candidate gene for genetic disorders associated with alterations at 11p15.5. Sequence data for the human and mouse BM88 cDNAs have been deposited in the EMBL/GenBank Nucleotide Sequence Databases under accession numbers AF235030 and AF243130, respectively.

BM88/CEND1 coordinates cell cycle exit and differentiation of neuronal precursors

“…BM88 has recently emerged as part of a protein interaction network associated with inherited human ataxias, a group of diseases characterized by degeneration of cerebellar Purkinje cells (4). BM88 cloned from mammalian and chick brain (5,6) is an integral membrane protein composed of two 23-kDa polypeptide chains linked together by disulfide bridges. It is anchored to the membrane of intracellular organelles, including the outer membrane of mitochondria and endoplasmic reticulum, via a transmembrane domain so that the bulk of the protein faces toward the cytoplasm (6, 7).…”

BM88 Is a Dual Function Molecule Inducing Cell Cycle Exit and Neuronal Differentiation of Neuroblastoma Cells via Cyclin D1 Down-regulation and Retinoblastoma Protein Hypophosphorylation

“…BM88 cloned from mammalian brain (26,27) is an integral membrane protein composed of two 22-23-kDa polypeptide chains linked together by disulfide bridges. It is anchored to the membrane of intracellular organelles, including the outer membrane of mitochondria, the endoplasmic reticulum, and other electrolucent vesicles, via a transmembrane domain so that the bulk of the protein faces toward the cytoplasm (25,26).…”

Coordination of cell cycle exit and differentiation of neuronal progenitors

“…[24][25][26] Interestingly, the human BM88/Cend1 gene is localized in chromosome 11p15.5, a region associated with human diseases. 25 The human 11p15.5 region contains an important tumour-suppression locus implicated in several childhood and adult cancers, [28][29][30] and it is also associated with the overgrowth genetic disorder Beckwith-Wiedemann syndrome (BWS). [31][32][33][34][35][36][37] Characterization of the human BM88/Cend1 promoter revealed an 88 bp proximal promoter fragment which is sufficient to confer neuron-specific transcriptional activity.…”

“…23,24 BM88/Cend1 cloned from porcine, mouse, human and, more recently, chick brain is an integral membrane protein composed of two 22-23 kDa polypeptide chains linked together by disulphide bridges. [25][26][27] It is anchored to the membrane of intracellular organelles, including the outer membrane of mitochondria, the endoplasmic reticulum and other electrolucent vesicles, via a transmembrane domain, in a way that the bulk of the protein faces towards the cytoplasm. [24][25][26] Interestingly, the human BM88/Cend1 gene is localized in chromosome 11p15.5, a region associated with human diseases.…”

“…[25][26][27] It is anchored to the membrane of intracellular organelles, including the outer membrane of mitochondria, the endoplasmic reticulum and other electrolucent vesicles, via a transmembrane domain, in a way that the bulk of the protein faces towards the cytoplasm. [24][25][26] Interestingly, the human BM88/Cend1 gene is localized in chromosome 11p15.5, a region associated with human diseases. 25 The human 11p15.5 region contains an important tumour-suppression locus implicated in several childhood and adult cancers, [28][29][30] and it is also associated with the overgrowth genetic disorder Beckwith-Wiedemann syndrome (BWS).…”