Background: Proteins involved in expression of histone genes co-localize to discrete nuclear structures called histone locus bodies (HLBs). Results: Two main components of HLBs directly interact with each other through their C-terminal regions. Conclusion: Formation of HLBs depends on a subset of critical protein-protein interactions. Significance: Our work may help to understand the mechanisms that integrate transcription of histone genes with maturation of the nascent histone transcripts.

3-end cleavage of histone pre-mRNAs is catalyzed by CPSF-73 and requires the interaction of two U7 snRNPassociated proteins, FLASH and Lsm11. Here, by using scanning mutagenesis we identify critical residues in human FLASH and Lsm11 that are involved in the interaction between these two proteins. We also demonstrate that mutations in the region of FLASH located between amino acids 50 and 99 do not affect binding of Lsm11. Interestingly, these mutations convert FLASH into an inhibitory protein that reduces in vitro processing efficiency of highly active nuclear extracts. Our results suggest that this region in FLASH in conjunction with Lsm11 is involved in recruiting a yet-unknown processing factor(s) to histone pre-mRNA. Following endonucleolytic cleavage of histone pre-mRNA, the downstream cleavage product (DCP) is degraded by the 5-3 exonuclease activity of CPSF-73, which also depends on Lsm11. Strikingly, while cleavage of histone pre-mRNA is stimulated by FLASH and inhibited by both dominant negative mutants of FLASH and anti-FLASH antibodies, the 5-3 degradation of the DCP is not affected. Thus, the recruitment of FLASH to the processing complex plays a critical role in activating the endonuclease mode of CPSF-73 but is dispensable for its 5-3 exonuclease activity. These results suggest that CPSF-73, the catalytic component in both reactions, can be recruited to histone pre-mRNA largely in a manner independent of FLASH, possibly by a separate domain in Lsm11.Animal replication-dependent histone pre-mRNAs are processed at the 3Ј end by an endonucleolytic cleavage that is not followed by polyadenylation (3, 4). The reaction depends on two sequence elements: a highly conserved stem-loop structure and a divergent sequence referred to as the histone downstream element (HDE) that begins approximately 15 nucleotides 3Ј of the stem. Histone pre-mRNAs are cleaved between the two sequence elements, resulting in the formation of mature histone mRNAs ending with the stem-loop followed by an ACCCA single-stranded tail (Fig. 1A). In vitro, the downstream cleavage product (DCP) is rapidly degraded in the 5Ј to 3Ј direction (19,21). This activity may play an important role in recycling the U7 snRNP and terminating transcription on histone genes (21).The stem-loop interacts with the stem-loop binding protein (SLBP), whereas the HDE base pairs with the 5Ј end of U7 snRNA, the approximately 60-nucleotide component of the U7 snRNP (3). The U7 snRNA associates with a unique Sm complex in which Lsm10 and Lsm11 substitute for SmD1 and SmD2, two canonical proteins found in the spliceosomal snRNPs (13,14). The cleavage reaction is catalyzed by CPSF-73 (6) and requires at least two other factors shared with cleavage/polyadenylation: symplekin and CPSF-100 (9, 10, 17).CPSF-73, in addition to its endonuclease activity (12), displays a 5Ј-3Ј exonuclease activity that is responsible for degradation of the DCP in histone pre-mRNA (21). In mammalian nuclear extracts, cleavage of histone pre-mRNAs can occur in the absence of SLBP if the U7...

Background & Aims Fecal incontinence (FI) affects 15% of people age 70 years and older, but only 10%–30% discuss FI with their physicians. We aimed to identify barriers that prevent people from consulting with their physicians, and physicians from screening for FI. Methods We performed structured interviews of 124 individuals with FI (mean 56 years old, 87.9% women) recruited from 6 medical offices at the University of North Carolina Hospitals from June 2012 through March 2013. The subjects completed the Fecal Incontinence Severity Index and Fecal Incontinence Quality of Life Scale questionnaires. Interview questions aimed to determine which patients had consulted physicians for FI. Eleven of the 56 physicians with patients included in the study responded to the survey. Results Eighty-eight of the 124 participants consulted with their physicians about FI (consulters). These individuals had a higher incidence of depression than the 36 subjects who did not consult with their physicians about FI (non-consulters; P=.04), but similar Fecal Incontinence Severity Index scores. A smaller proportion of non-consulters were aware of available treatments than consulters (P<.01). Fifty-six percent of non-consulters said their FI was not serious enough to consult a physician. There was no difference between consulters and non-consulters in embarrassment in talking about FI. Among consulters, 88% initiated the conversation about FI with their physician. Seven of the 11 responding physicians screened for FI, and only screened high-risk patients. The 4 physicians who did not screen for FI were unaware of its prevalence, viewed FI as a low priority, or stated that patients were responsible for reporting their own symptoms. Conclusions Based on surveys of physicians and patients, many patients have insufficient knowledge about the availability and effectiveness of treatments for FI. Some people with FI do not discuss it with their physician because their symptoms are mild, and most prefer physicians to ask them directly about FI. Educating patients and physicians about the prevalence of FI and management strategies may improve rates of consultation rates.

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