It is generally assumed that both copies of an autosomal gene will be transcribed equally over time by any cell that expresses that gene. However, recent research has indicated that this is not the case for approximately 10% of human autosomal genes. For genes that undergo random autosomal monoallelic expression (RAMAE), only one allele is expressed in any given cell and its mitotic daughters. Each cell’s ‘choice’ of allele appears to be made at random, and differs from one cell to another. Though the overall allele bias of a RAMAE gene may be low at an organism and tissue level, this alternative mode of expression still alters expectations for how allele products will interact within the cells of heterozygotes.
Previously, study of RAMAE has largely relied on single-cell culture platforms, which are expensive to set up and use and are not amenable to all types of cultured cells. To overcome this obstacle to further research, we are developing an alternative approach for investigating RAMAE, using a combination of molecular beacons (MBs) and fluorescence-activated cell sorting (FACS). By targeting fluorescently-tagged MBs to unique regions of RAMAE Growth Hormone Receptor (GHR) alleles in heterozygous lymphoblast cell lines, we can visualise the allele choice of individual cells. These cells can then be segregated from each other with FACS, creating two distinct populations that can be used for further experimentation and analysis.
Because this MB-FACS technique should be easily adaptable to other RAMAE genes and cell cultures, we anticipate that it will facilitate further research into RAMAE and potentially enable the development of new treatments for many genetic diseases.