Research Awards
Janine M. LaSalle, Ph.D.
University of California, Davis
"The Role of MECP2 in Parental Imprinting"
2-Year Award: $99,522
Lay Progress Report (August 2002)
Rett syndrome is caused by mutations in the MECP2 gene on the X chromosome. Females with RTT have two X chromosomes, one with the mutant and one with the normal MECP2. Because of X inactivation in females, a process in which one X chromosome is randomly inactivated in each cell, RTT girls are mosaic for cells containing either the mutant or normal MeCP2 protein. We have used two different approaches to identifying cells with mutant MeCP2 in blood and brain of female RTT patients. From blood, the technique of single cell cloning was performed in order to separate cells containing mutant and normal MeCP2 proteins. T cell clones with mutant MeCP2 were isolated from four different RTT patients, but were always less frequent than clones with normal MeCP2. These results demonstrate that MECP2 mutations adversely affect lymphocyte growth. No difference was observed between normal and mutant cells in the expression of four different genes regulated by methylation or parental imprinting. For detection of mutant and normal MeCP2 in brain, we have used the novel technology of laser scanning cytometry to quantitatively detect the normal but not mutant MeCP2 protein. Brain cells with mutant MeCP2 were randomly distributed. Surprisingly, there were two different populations of cells based on amount of MeCP2 in normal brain samples. The elevated expression of MeCP2 was demonstrated to be unique to tissues in the central nervous system, providing a potential explanation for the specific neurologic symptoms in RTT. These results are expected to be important in understanding the role of MeCP2 in the pathogenesis of RTT and in designing therapies.
Janine M. LaSalle, Ph.D.University of California, Davis
"The Role of MECP2 in Parental Imprinting"
2-Year Award: $99,522
Lay Progress Report (August 2002)
Rett syndrome is caused by mutations in the MECP2 gene on the X chromosome. Females with RTT have two X chromosomes, one with the mutant and one with the normal MECP2. Because of X inactivation in females, a process in which one X chromosome is randomly inactivated in each cell, RTT girls are mosaic for cells containing either the mutant or normal MeCP2 protein. We have used two different approaches to identifying cells with mutant MeCP2 in blood and brain of female RTT patients. From blood, the technique of single cell cloning was performed in order to separate cells containing mutant and normal MeCP2 proteins. T cell clones with mutant MeCP2 were isolated from four different RTT patients, but were always less frequent than clones with normal MeCP2. These results demonstrate that MECP2 mutations adversely affect lymphocyte growth. No difference was observed between normal and mutant cells in the expression of four different genes regulated by methylation or parental imprinting. For detection of mutant and normal MeCP2 in brain, we have used the novel technology of laser scanning cytometry to quantitatively detect the normal but not mutant MeCP2 protein. Brain cells with mutant MeCP2 were randomly distributed. Surprisingly, there were two different populations of cells based on amount of MeCP2 in normal brain samples. The elevated expression of MeCP2 was demonstrated to be unique to tissues in the central nervous system, providing a potential explanation for the specific neurologic symptoms in RTT. These results are expected to be important in understanding the role of MeCP2 in the pathogenesis of RTT and in designing therapies.