Expression profiling in tuberous sclerosis complex (TSC) knockout mouse astrocytes to characterize human TSC brain...

Individuals with tuberous sclerosis complex (TSC) exhibit a variety of neurologic abnormalities, including mental retardation, epilepsy, and autism. Examination of human TSC brains demonstrate dysplastic astrocytes and neurons, areas of abnormal neuronal migration (tubers), and hamartomatous growths, termed subependymal nodules, which can progress to subependymal giant cell astrocytomas (SEGA). Previous studies have suggested that these neuropathologic features may result from abnormal neuroglial cell differentiation. In an effort to provide support for this hypothesis and to identify specific markers of aberrant neuroglial cell differentiation in TSC, we employed gene expression profiling on Tsc1 conditional knockout (Tsc1(GFAP)CKO) mouse astrocytes. We identified several transcripts implicated in central nervous system development that are differentially expressed in Tsc1(-/-) astrocytes compared to wild-type astrocytes. We validated the differential expression of select transcripts on the protein level both in primary cultures of Tsc1(-/-) astrocytes and in Tsc1(GFAP)CKO mouse brains. Moreover, we show that these markers are also differentially expressed within cortical tubers, but not in adjacent normal tissue from TSC patient brains. This study provides supportive evidence for a developmental defect in neuroglial cell differentiation relevant to the genesis of TSC nervous system pathology and underscores the utility of mouse modeling for understanding the molecular pathogenesis of human disease.