RESTORATION OF THE CHOLESTEROL-METABOLISM IN 3T3 CELL-LINES DERIVED FROM THE SPHINGOMYELINOSIS MOUSE (SPM SPM) BY TRANSFER OF A HUMAN CHROMOSOME-18/

We searched for a human chromosome that would restore the cholesterol metabolism in 3T3 cell lines (SPM-3T3) derived from homozygous sphingo myelinosis mice (spm/spm). Mouse A9 cells containing a single copy of pSV2neo-tagged chromosomes 9, 11, or 18 derived from normal human fibr oblasts served as donor cells for transfer of human chromosomes. Purif ied A9 microcells were fused with SPM-3T3 cells, and the microcell hyb rids were selected in medium containing G418 antibiotics. The microcel l hybrids that contained human chromosomes 9, 11, or 18 in a majority of cells were examined. The accumulation of intracellular cholesterol in the microcell hybrids containing a chromosome 18 decreased markedly , whereas in the microcell hybrids containing either chromosomes 9 or 11 it was similar to that in SPM-3T3 cells. The SPM-3T3 cells with an intact chromosome 18 were further passaged and subcloned. Clones which again accumulated intracellular cholesterol had concurrently lost the introduced chromosome 18. The abnormal accumulation was associated wi th a decrement in the esterification of exogenous cholesterol. These f indings suggest that the gene responsible for the abnormal cholesterol metabolism in the spm/spm mice can be restored by a human chromosome 18. The gene was tentatively mapped on 18pter-->18p11.3 or 18q21.3-->q ter that was lost during subcloning, thereby resulting in reaccumulati on of the intracellular cholesterol.