La Ribonucleoprotein Domain Family, Member 7 (LARP7)

Nearly all nuclear 7SK was associated with PIP7S, and knockdown of PIP7S with short hairpin RNA (shRNA) reduced the levels of 7SK, indicating that PIP7S is required for 7SK stability. Moreover, knockdown of PIP7S with shRNA prevented formation of the 7SK snRNP and enhanced P-TEFb-dependent expression of a human immunodeficiency virus (HIV)-1 long terminal repeat(LTR)-driven reporter gene. Mutation analysis revealed that interaction of PIP7S with 7SK required the La and RRM motifs of PIP7S and the 3-prime UUU(OH) tail of 7SK, suggesting that PIP7S stabilizes 7SK against degradation by 3-prime exonucleases. Knockdown of PIP7S with shRNA in a normal human mammary epithelial cell line disrupted epithelial differentiation and cell morphology and caused P-TEFb-dependent malignant transformation.