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Introduction Deep venous thrombosis (DVT) is a common vascular disease with an annual incidence of 0.1% among the general population, and more than 1% among hospitalized individuals (1). Pulmonary embolism--the [...], Deep venous thrombosis (DVT) and secondary pulmonary embolism cause approximately 100,000 deaths per year in the United States. Physical immobility is the most significant risk factor for DVT, but a molecular and cellular basis for this link has not been defined. We found that the endothelial cells surrounding the venous valve, where DVTs originate, express high levels of FOXC2 and PROX1, transcription factors known to be activated by oscillatory shear stress. The perivalvular venous endothelial cells exhibited a powerful antithrombotic phenotype characterized by low levels of the prothrombotic proteins vWF, P-selectin, and ICAM1 and high levels of the antithrombotic proteins thrombomodulin (THBD), endothelial protein C receptor (EPCR), and tissue factor pathway inhibitor (TFPI). The perivalvular antithrombotic phenotype was lost following genetic deletion of FOXC2 or femoral artery ligation to reduce venous flow in mice, and at the site of origin of human DVT associated with fatal pulmonary embolism. Oscillatory blood flow was detected at perivalvular sites in human veins following muscular activity, but not in the immobile state or after activation of an intermittent compression device designed to prevent DVT. These findings support a mechanism of DVT pathogenesis in which loss of muscular activity results in loss of oscillatory shear-dependent transcriptional and antithrombotic phenotypes in perivalvular venous endothelial cells, and suggest that prevention of DVT and pulmonary embolism may be improved by mechanical devices specifically designed to restore perivalvular oscillatory flow.

rRNA transcription is a fundamental requirement for all cellular growth processes and is activated by the phosphorylation of the upstream binding factor (UBF) in response to growth stimulation. Even though it is well known that phosphorylation of UBF is required for its activation and is a key step in activation of rRNA transcription, as yet, there has been no direct mapping of the UBF phosphorylation sites. The results of the present studies employed sophisticated nano-flow HPLC-microelectrospray-ionization tandem mass spectrometry (nHPLC-[mu]ESI-MS/MS) coupled with immobilized metal affinity chromatography (IMAC) and computer database searching algorithms to identify 10 phosphorylation sites on UBF at serines 273, 336, 364, 389, 412, 433, 484, 546, 584, and 638. We then carried out functional analysis of two of these sites, serines 389 and 584. Serine-alanine substitution mutations of 389 (S389A) abrogated rRNA transcription in vitro and in vivo, whereas mutation of serine 584 (S584A) reduced transcription in vivo but not in vitro. In contrast, serine-glutamate mutation of 389 (S389E) restored transcriptional activity. Moreover, $389A abolished UBF-SL1 interaction in vitro, while S389E partially restored UBF-SL1 interaction. Taken together, the results of these studies suggest that growth factor stimulation induces an increase in rRNA transcriptional activity via phosphorylation of UBF at serine 389 in part by facilitating a rate-limiting step in the recruitment of RNA polymerase I: i.e., recruitment of SL1. Moreover, studies provide critical new data regarding multiple additional UBF phosphorylation sites that will require further characterization by the field. immobilized metal affinity chromatography; mass spectrometry; UBF; TBP; RNA polymerase I doi:10.1152/ajpcell.00176.2006.

Knockout of transforming growth factor (TGF)-[beta]1 or components of its signaling pathway leads to embryonic death in mice due to impaired yolk sac vascular development before significant smooth muscle cell (SMC) maturation occurs. Thus the role of TGF-[beta]1 in SMC development remains unclear. Embryonic stem cell (ESC)derived embryoid bodies (EBs) recapitulate many of the events of early embryonic development and represent a more physiological context in which to study SMC development than most other in vitro systems. The present studies showed induction of the SMC-selective genes smooth muscle [alpha]-actin (SM[alpha]A), SM22[alpha], myocardin, smoothelin-B, and smooth muscle myosin heavy chain (SMMHC) within a mouse ESC-EB model system. Significantly, SM2, the SMMHC isoform associated with fully differentiated SMCs, was expressed. Importantly, the results showed that aggregates of SMMHC-expressing cells exhibited visible contractile activity, suggesting that all regulatory pathways essential for development of contractile SMCs were functional in this in vitro model system. Inhibition of endogenous TGF-[beta] with an adenovirus expressing a soluble truncated TGF-[beta] type II receptor attenuated the increase in SMC-selective gene expression in the ESC-EBs, as did an antibody specific for TGF-[beta]1. Of interest, the results of small interfering (si)RNA experiments provided evidence for differential TGF-[beta]-Smad signaling for an early vs. late SMC marker gene in that SM[alpha]A promoter activity was dependent on both Smad2 and Smad3 whereas SMMHC activity was Smad2 dependent. These results are the first to provide direct evidence that TGF-[beta]1 signaling through Smad2 and Smad3 plays an important role in the development of SMCs from totipotential ESCs. embryoid body; Smad

rRNA transcription is a fundamental requirement for all cellular growth processes and is activated by the phosphorylation of the upstream binding factor (UBF) in response to growth stimulation. Even though it is well known that phosphorylation of UBF is required for its activation and is a key step in activation of rRNA transcription, as yet, there has been no direct mapping of the UBF phosphorylation sites. The results of the present studies employed sophisticated nanoflow HPLC-microelectrospray-ionization tandem mass spectrometry (nHPLC-µESI-MS/MS) coupled with immobilized metal affinity chromatography (IMAC) and computer database searching algorithms to identify 10 phosphorylation sites on UBF at serines 273, 336, 364, 389, 412, 433, 484, 546, 584, and 638. We then carried out functional analysis of two of these sites, serines 389 and 584. Serine-alanine substitution mutations of 389 (S389A) abrogated rRNA transcription in vitro and in vivo, whereas mutation of serine 584 (S584A) reduced transcription in vivo but not in vitro. In contrast, serine-glutamate mutation of 389 (S389E) restored transcriptional activity. Moreover, S389A abolished UBF-SL1 interaction in vitro, while S389E partially restored UBF-SL1 interaction. Taken together, the results of these studies suggest that growth factor stimulation induces an increase in rRNA transcriptional activity via phosphorylation of UBF at serine 389 in part by facilitating a rate-limiting step in the recruitment of RNA polymerase I: i.e., recruitment of SL1. Moreover, studies provide critical new data regarding multiple additional UBF phosphorylation sites that will require further characterization by the field. [ABSTRACT FROM AUTHOR]

Background: Trauma is a major cause of mortality in the elderly population. Hyponatremia is the most common electrolyte imbalance in geriatric patients and has been demonstrated to be a risk factor for altered cognition, low bone density, falls, and death. We systematically and critically reviewed the literature to ascertain the association between hyponatremia and geriatric trauma outcomes., Methods: We searched seven databases for articles published from inception to October 2023. Studies included reported on geriatric trauma, hyponatremia, and clinical outcomes. Two investigators independently reviewed 6535 abstracts, 235 full-text articles, and critically appraised each study. Study details, patient characteristics, and outcomes were independently extracted by two reviewers. Data quality assessment was performed using the Grading of Recommendations Assessment, Development, and Evaluation approach. Publication bias was assessed using funnel plot-based methods. A meta-analysis of risk ratios (RR) was performed using the random effects method., Results: Four retrospective cohort studies involving 11 894 geriatric patients were included. Among these, 492 (21.4%) were classified as trauma patients due to a fall and 1806 (78.6%) were classified as a trauma patient due to the presence of a fracture. In total, 2298 (19.3%) patients were classified as hyponatremic (125-135 mmol/L) while 9596 (80.7%) were classified as normonatremic. The pooled RR for in-hospital mortality for hyponatremic patients was 2.23 (95% CI 1.51 to 3.74) with high heterogeneity across the studies (I 2 =82.17%)., Conclusions: Geriatric trauma patients presenting with hyponatremia appear to have an increased risk of in-hospital mortality. Given this association, national trauma registries should consider collecting serum sodium values for geriatric patients and providers should work to address hyponatremia as a possible contribution to falls. Given the paucity of published literature on this topic, there is a need for prospective studies evaluating the association between hyponatremia and geriatric trauma outcomes., Level of Evidence: Level III, systematic review with meta-analysis., Competing Interests: None declared., (Copyright © Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.)

Myocardin is a serum response factor (SRF) coactivator exclusively expressed in cardiomyocytes and smooth muscle cells (SMCs). However, there is highly controversial evidence as to whether myocardin is essential for normal differentiation of these cell types, and there are no data showing whether cardiac or SMC subtypes exhibit differential myocardin requirements during development. Results of the present studies showed the virtual absence of myocardin(-/-) visceral SMCs or ventricular myocytes in chimeric myocardin knockout (KO) mice generated by injection of myocardin(-/-) embryonic stem cells (ESCs) into wild-type (WT; i.e., myocardin(+/+) ESC) blastocysts. In contrast, myocardin(-/-) ESCs readily formed vascular SMC, albeit at a reduced frequency compared with WT ESCs. In addition, myocardin(-/-) ESCs competed equally with WT ESCs in forming atrial myocytes. The ultrastructural features of myocardin(-/-) vascular SMCs and cardiomyocytes were unchanged from their WT counterparts as determined using a unique X-ray microprobe transmission electron microscopic method developed by our laboratory. Myocardin(-/-) ESC-derived SMCs also showed normal contractile properties in an in vitro embryoid body SMC differentiation model, other than impaired thromboxane A2 responsiveness. Together, these results provide novel evidence that myocardin is essential for development of visceral SMCs and ventricular myocytes but is dispensable for development of atrial myocytes and vascular SMCs in the setting of chimeric KO mice. In addition, results suggest that as yet undefined defects in development and/or maturation of ventricular cardiomyocytes may have contributed to early embryonic lethality observed in conventional myocardin KO mice and that observed deficiencies in development of vascular SMC may have been secondary to these defects.

Smooth muscle cells (SMCs) play a key role in vascular physiology and pathology. An appreciation of normal SMCs developmental mechanisms will likely lead to a better understanding of disease processes and potentially to novel treatment strategies. We present a method for generating relatively pure populations of SMCs from embryonic stem cells (ESC) which display appropriate excitation and contractile responses to vasoactive agonists. We also present protocols for assessment of SMCs purity and identity by immunofluorescence, quantitative RT-PCR, and FACS. This ESC-based system has tremendous potential for studying developmental regulation of SMC lineage, as well as for possible SMC tissue engineering.

Previous studies demonstrated that angiotensin II (Ang II)-induced hypertrophy of smooth muscle cells (SMCs) was associated with increased transcription of SM alpha-actin gene. The aim of the present study was to determine whether myocardin, a SMC-selective cofactor of serum response factor (SRF), contributed to Ang II-induced increases in SM alpha-actin transcription. Results showed that Ang II increased myocardin mRNA expression as well as SM alpha-actin mRNA expression via the Ang II type 1 receptor in cultured rat aortic SMCs. Cotransfection studies revealed that CArG elements were required for Ang II-induced transcription of SM alpha-actin gene, and a dominant-negative form of myocardin or a short interfering RNA (siRNA) specific for myocardin decreased Ang II-induced SM alpha-actin transcription. Prx1, a homeodomain protein whose expression was increased by Ang II, also increased SM alpha-actin gene transcription in part via CArG elements, and siRNA specific for Prx1 markedly decreased basal and Ang II-induced SM alpha-actin transcription. Electrophoretic mobility shift assay showed that myocardin and Ang II, respectively, increased formation of a SMC-specific CArG-SRF-myocardin higher order complex. However, Ang II had no effect on binding between myocardin and SRF as determined by a mammalian two-hybrid assay, suggesting that Ang II-induced increases in formation of CArG-SRF-myocardin complex was the result of increased SRF binding to CArG elements and increased myocardin expression. Taken together, these results support a model in which Ang II-induced increases in expression of SM alpha-actin are mediated through Prx1-dependent increases in SRF binding to CArG elements and subsequent recruitment of myocardin.