This model is supported experimentally, as reducing U1 snRNP levels with antisense morpholino oligonucleotides led to a dose-dependent shift of polyA usage to generate shorter mRNA transcripts.

[7][8] U1 overexpression elevates the expression level of autophagy and alters lysosomal biogenesis[9] Similarly in fibroblast cells of patients with a familial form of amyotrophic lateral sclerosis (ALS), the core components of U1 snRNP (namely, the Sm proteins and U1 snRNA) were found to co-mislocalize to the cytoplasm with the mutant version of a protein called FUS (ideally, FUS should localize to the nucleus since it possesses an exposed nuclear localization sequence).

The authors of this study also found that experimentally knocking down U1 snRNP, lead to truncations in the axons of motor neurons, suggesting that splicing defects might have a role to play in ALS pathogenesis.

[11] In addition to its role in 5' splice site recognition, U1 snRNP protects nascent transcripts by sheltering these exposed PAS in the pre-mRNA such that elongation can continue.

Moreover, it has been found that U1 telescripting is particularly important for long-distance transcription elongation in introns of large genes that have a median size of 39 kilo base pairs.