Phosphorylation of the smooth muscle master splicing regulator RBPMS regulates its splicing activity.

We previously identified RBPMS as a master regulator of alternative splicing in differentiated smooth muscle cells (SMCs). RBPMS is transcriptionally downregulated during SMC dedifferentiation, but we hypothesized that RBPMS protein activity might be acutely downregulated by post-translational modifications. Publicly available phosphoproteomic datasets reveal that Thr113 and Thr118 immediately adjacent to the RRM domain are commonly both phosphorylated. An RBPMS T113/118 phosphomimetic T/E mutant showed decreased splicing regulatory activity both in transfected cells and in a cell-free in vitro assay, while a non-phosphorylatable T/A mutant retained full activity. Loss of splicing activity was associated with a modest reduction in RNA affinity but significantly reduced RNA binding in nuclear extract. A lower degree of oligomerization of the T/E mutant might cause lower avidity of multivalent RNA binding. However, NMR analysis also revealed that the T113/118E peptide acts as an RNA mimic which can loop back and antagonize RNA-binding by the RRM domain. Finally, we identified ERK2 as the most likely kinase responsible for phosphorylation at Thr113 and Thr118. Collectively, our data identify a potential mechanism for rapid modulation of the SMC splicing program in response to external signals during the vascular injury response and atherogenesis.

Factors affecting long-term survival in patients with recurrent head and neck cancer may help define the role of post-treatment surveillance.

OBJECTIVES/HYPOTHESIS: Assess impact of clinical variables upon survival in patients diagnosed with recurrent head and neck carcinoma and better delineate role of post-treatment surveillance. METHODS: Variables including previous tumor site, stage, prior therapy, location of recurrence, patient-identified symptoms, compliance with recommended surveillance, definitive salvage therapy, and clinical outcome were recorded for patients diagnosed with recurrent head and neck cancer from which estimates of survival were generated and compared. RESULTS: One hundred five patients were identified as having been diagnosed with recurrent disease. The majority (81%) were deemed compliant with recommended surveillance. Eighty-nine patients (85%) identified new symptoms/findings prior to diagnosis. Survival was not significantly different between compliant and noncompliant patients (P = .20). For patients who underwent salvage therapy, no significant differences in survival were seen according to original primary site or mode of treatment for recurrence. Better survival was seen in patients with original prior early stage disease (P = .0001) and in patients with local-only site of disease recurrence (P = .0001). CONCLUSIONS: In patients with recurrent disease, survival may relate more to variables associated with prior disease or recurrence location than those associated with follow-up surveillance. Surveillance and salvage therapy for recurrent disease may, however, preferentially benefit certain subgroups: 1) patients with prior early stage disease, and 2) those in whom site of recurrence is local-only. Despite high compliance with recommended surveillance, survival remains extremely poor for patients with recurrent disease previously treated for advanced stage disease or with those with regional recurrence. As such, the impact of routine surveillance upon survival in these patients remains unclear.