hnRNP L regulates differences in expression of mouse integrin alpha2beta1.
There is a 2-fold variation in platelet integrin alpha2beta1 levels among inbred mouse strains. Decreased alpha2beta1 in 4 strains carrying Itga2 haplotype 2 results from decreased affinity of heterogeneous ribonucleoprotein L (hnRNP L) for a 6 CA repeat sequence (CA6) within intron 1. Seven strains bearing haplotype 1 and a 21 CA repeat sequence at this position (CA21) express twice the level of platelet alpha2beta1 and exhibit an equivalent gain of platelet function in vitro. By UV crosslinking and immunoprecipitation, hnRNP L binds more avidly to CA21, relative to CA6. By cell-free, in vitro mRNA splicing, decreased binding of hnRNP L results in decreased splicing efficiency and an increased proportion of alternatively spliced product. The splicing enhancer activity of CA21 in vivo is abolished by prior treatment with hnRNP L-specific siRNA. Thus, decreased surface alpha2beta1 results from decreased Itga2 pre-mRNA splicing regulated by hnRNP L and depends on CA repeat length at a specific site in intron 1.
Cheli
Yann
Y
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
Kunicki
Thomas J
TJ
D017398:Alternative Splicing; D000818:Animals; D001665:Binding Sites; D001792:Blood Platelets; D005786:Gene Expression Regulation; D006239:Haplotypes; D034664:Heterogeneous-Nuclear Ribonucleoprotein L / Q000502:physiology*; D038982:Integrin alpha2beta1 / Q000235:genetics*; D007438:Introns; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D011485:Protein Binding; D013045:Species Specificity
D034664:Heterogeneous-Nuclear Ribonucleoprotein L; D038982:Integrin alpha2beta1