WBP11 is required for splicing the TUBGCP6 pre-mRNA to promote centriole duplication

Centriole duplication occurs once in each cell cycle to maintain centrosome number. A previous genome-wide screen revealed that depletion of 14 RNA splicing factors leads to a specific defect in centriole duplication, but the cause of this deficit remains unknown. Here, we identified an additional pre-mRNA splicing factor, WBP11, as a novel protein required for centriole duplication. Loss of WBP11 results in the retention of ∼200 introns, including multiple introns in TUBGCP6, a central component of the γ-TuRC. WBP11 depletion causes centriole duplication defects, in part by causing a rapid decline in the level of TUBGCP6. Several additional splicing factors that are required for centriole duplication interact with WBP11 and are required for TUBGCP6 expression. These findings provide insight into how the loss of a subset of splicing factors leads to a failure of centriole duplication. This may have clinical implications because mutations in some spliceosome proteins cause microcephaly and/or growth retardation, phenotypes that are strongly linked to centriole defects.

Direct regulation of Chk1 protein stability by E3 ubiquitin ligase HUWE1

The HECT E3 ubiquitin ligase HUWE1 is required for a wide array of important functions in cell biology. Although HUWE1 is known to play a role in DNA damage signaling, the mechanism(s) that underlie this function remain elusive. HUWE1 regulates effectors of DNA replication and genotoxic stress tolerance. However, the loss of HUWE1 can also result in the accrual of significant endogenous DNA damage due to insufficient remediation of replication stress induced by an overabundance of key substrates. We discovered that HUWE1 depletion leads to a significant increase in levels of the single-strand break effector kinase Chk1, independent of the DNA damage response, activation of apical DNA damage repair (DDR) signaling kinases (ATM and ATR), and the tumor suppressor p53. We also identified multiple lysine residues on Chk1 that are polyubiquitinated by HUWE1 in vitro, many of which are within the kinase domain. HUWE1 knockdown also markedly prolonged the protein half-life of Chk1 in steady-state conditions and resulted in greater stabilization of Chk1 protein than depletion of Cul4A, an E3 ubiquitin ligase previously described to control Chk1 abundance. Moreover, prolonged replication stress induced by hydroxyurea or camptothecin resulted in a reduction of Chk1 protein levels, which was rescued by HUWE1 knockdown. Our study indicates that HUWE1 plays a significant role in the regulation of the DDR signaling pathway by directly modulating the abundance of Chk1 protein.

Dyspnea duration, distress, and intensity in emergency department visits for heart failure

BACKGROUND

Dyspnea is the most common symptom among patients with heart failure (HF) who present to the emergency department (ED), but it is not clear which dimensions of the symptom prompt ED visits, or whether dyspnea characteristics are related to visit disposition.

PURPOSE

The goal of this study was to explore the influence of dyspnea duration, distress, and intensity on decisions of patients with HF to come to an ED and the disposition of visits.

METHODS

The study population consisted of patients treated for HF in an urban university hospital ED (N = 57) who were interviewed retrospectively. Open-ended questions pertained to symptoms in general and dyspnea at the time of the visit. Subjects rated recalled dyspnea distress (0 = not at all bothered by breathing; 4 = bothered very much by breathing) for when they decided to come to the ED (Decision) and a week before the visit (Week Before), as well as duration--the number of days before the visit that dyspnea was recalled as having been as severe as at Decision. After the interviews, a subsample (n = 34) rated the intensity of a set of dyspnea sensory quality descriptors for Decision and Week Before (0 = not endorsed; 1 = very mild; 10 = very severe). Charts were also reviewed.

RESULTS

Seventy percent recalled dyspnea as the most distressing symptom at Decision, or the primary reason for the visit; 88% were admitted. Dyspnea duration was unrelated to admission. Duration was 3 days or less for 65% of the sample, but 6 days or more for 35%. There was no duration-related difference in dyspnea distress or intensity at Decision, but subjects with a duration < or =3 days reported lower levels of both dimensions for Week Before with significant increases from Week Before to Decision. Those with longer episodes reported high levels of distress and intensity in both time frames with no significant change in either dimension.

CONCLUSION

Subjects reported high levels of distress and intensity at Decision, regardless of dyspnea duration. Differences in recalled duration were associated with 2 distinct patterns in distress and intensity ratings but were not associated with admission. Dyspnea duration does not appear to be a valid criterion for judging condition severity in HF-related visits to the ED.

Reliability and validity of dyspnea sensory quality descriptors in heart failure patients treated in an emergency department

BACKGROUND

Sensory qualities of dyspnea are known to differ by diagnosis. Less is known about whether sensory qualities vary with changes in health status in a given diagnosis.

PURPOSE

The goal of this study was to evaluate the reliability, validity, and factor structure of dyspnea sensory quality descriptors in patients with heart failure (HF) treated in an emergency department (ED) and to investigate whether change in sensory quality influences HF patients to seek care in an ED.

METHODS

HF patients (N = 57) treated in an ED were interviewed retrospectively. Open-ended characterizations of dyspnea at the time of the ED visit were analyzed qualitatively. A subset of subjects (n = 34) rated the intensity of 13 dyspnea descriptors (0 = not endorsed; 1= very mild; 10 = very severe) as the descriptors applied to the time at which they decided to come to the ED (Decision) and a week before the visit (Week Before). Descriptor ratings were analyzed for congruence with open-ended characterizations, endorsement frequency, internal consistency, factor structure, and correlations (by descriptor and within subjects) between the 2 time frames.

RESULTS

Open-ended characterizations of dyspnea provided support for the content validity of most descriptors. Internal consistency of numerical ratings was high (alpha >0.90) in both recalled time frames. Factor analysis of descriptor ratings was unifactorial for Week Before, but suggested multiple sensory quality factors at Decision (suffocation, air hunger, effort/impedance, and, possibly, rate). Within-subject concordance and descriptor-by-descriptor correlations across time frames were mostly low, suggesting change in sensory quality from Week Before to Decision. Correlations in descriptor ratings were lowest among subjects who reported duration of dyspnea (as severe as at Decision) of 3 days or less. Subjects who recalled a duration of 6 days or more gave highly concordant ratings across both time frames.

CONCLUSION

Sensory quality descriptor-based ratings were internally consistent and content valid. Low correlations in ratings of sensory quality for most subjects across recalled time frames suggest that change in sensory quality may be an aspect of perceived increases in dyspnea severity before an ED visit. Results require replication and extension with larger samples and other diagnoses.