The functional role of A-type lamin interacting transcription factor (LITF) during skeletal myogenesis

Abstract

Lamin A/C (LMNA) is ubiquitously expressed in tissues, however specific missense mutations in LMNA result in discrete tissue specific phenotypes such as muscular dystrophy. Using a yeast-two-hybrid assay against a human heart cDNA library, a previously uncharacterized cDNA clone, A-type lamin interacting transcription factor (LITF), was identified. In this thesis the major objective was to determine the function of LITF using C2C12 mouse myoblast cell line. It is hypothesized that LITF is a myogenic factor that is required for myogenesis. Initiation of C2C12 differentiation led to an increase in LITF protein expression by 6 hours and peaking at 18 hours. LITF mediated chromatin immunoprecipitation from C2C12 nuclei with array analysis revealed a significant enrichment (p<0.00001) of promoter regions of developmentally important muscle transcription factors (Six1, Six4, Mef2c, Myogenin) and several other genes implicated in cell cycle and differentiation. Electrophoretic mobility shift assays and co-transactivation experiments revealed that LITF is capable of binding specific DNA sequences and activating transcription. Specific knockdown of LITF in C2C 12 led to a reduction in the expression of Myogenin, MyoD and myosin heavy chain with a significant reduction in myotube formation. Collectively this data suggests that LITF may be a myogenic transcription factor/regulator.