Alternative initiation and splicing in dicer gene expression in human breast cells

INTRODUCTION: Dicer is a ribonuclease that mediates RNA interference both at the transcriptional and the post-transcriptional levels. Human dicer gene expression is regulated in different tissues. Dicer is responsible for the synthesis of microRNAs and short temporal (st)RNAs that regulate the expression of many genes. Thus, understanding the control of the expression of the dicer gene is essential for the appreciation of double-stranded (ds)RNA-mediated pathways of gene expression. Human dicer mRNA has many upstream open reading frames (uORFs) at the 5'-leader sequences (the nucleotide sequence between the 5'-end and the start codon of the major ORF), and we studied whether these elements at the 5'-leader sequences regulate the expression of the dicer gene. METHOD: We determined the 5'-leader sequences of the dicer mRNAs in human breast cells by 5'-RACE and S1-nuclease protection analysis. We have analyzed the functions of the 5'-leader variants by reporter gene expression in vitro and in vivo. RESULTS: We found that the dicer transcripts in human breast cells vary in the sequence of their 5'-leader sequences, and that alternative promoter selection along with alternative splicing of the 5'-terminal exons apparently generate these variations. The breast cell has at least two predominant forms of dicer mRNAs, one of which has an additional 110 nucleotides at the 5'-end. Sequence comparison revealed that the first 80 nucleotides of these mRNA isoforms are encoded by a new exon located approximately 16 kb upstream of the reported start site. There are 30 extra nucleotides added to the previously reported exon 1. The human breast cells studied predominantly express two 5'-leader variants of dicer mRNAs, one with the exons 2 and 3 (long form) and the other without them (short form). By reporter gene expression analysis we found that the exon 2 and 3 sequences at the 5'-leader sequences are greatly inhibitory for the translation of the mRNA into protein. CONCLUSION: Dicer gene expression in human breast cells is regulated by alternative promoter selection to alter the length and composition of the 5'-leader sequence of its mRNA. Furthermore, alternative splicing of its exon 2 and 3 sequences of their pre-mRNA creates a more translationally competent mRNA in these cells

Modeling the Afferent Dynamics of the Baroreflex Control System

In this study we develop a modeling framework for predicting baroreceptor firing rate as a function of blood pressure. We test models within this framework both quantitatively and qualitatively using data from rats. The models describe three components: arterial wall deformation, stimulation of mechanoreceptors located in the BR nerve-endings, and modulation of the action potential frequency. The three sub-systems are modeled individually following well-established biological principles. The first submodel, predicting arterial wall deformation, uses blood pressure as an input and outputs circumferential strain. The mechanoreceptor stimulation model, uses circumferential strain as an input, predicting receptor deformation as an output. Finally, the neural model takes receptor deformation as an input predicting the BR firing rate as an output. Our results show that nonlinear dependence of firing rate on pressure can be accounted for by taking into account the nonlinear elastic properties of the artery wall. This was observed when testing the models using multiple experiments with a single set of parameters. We find that to model the response to a square pressure stimulus, giving rise to post-excitatory depression, it is necessary to include an integrate-and-fire model, which allows the firing rate to cease when the stimulus falls below a given threshold. We show that our modeling framework in combination with sensitivity analysis and parameter estimation can be used to test and compare models. Finally, we demonstrate that our preferred model can exhibit all known dynamics and that it is advantageous to combine qualitative and quantitative analysis methods

Cd70 Exacerbates Blood Pressure Elevation And Renal Damage In Response To Repeated Hypertensive Stimuli

Rationale: Accumulating evidence supports a role of adaptive immunity and particularly T cells in the pathogenesis of hypertension. Formation of memory T cells, which requires the costimulatory molecule CD70 on antigen-presenting cells, is a cardinal feature of adaptive immunity. Objective: To test the hypothesis that CD70 and immunologic memory contribute to the blood pressure elevation and renal dysfunction mediated by repeated hypertensive challenges. Methods and Results: We imposed repeated hypertensive challenges using either N-nitro-L-arginine methyl ester hydrochloride (L-NAME)/high salt or repeated angiotensin II stimulation in mice. During these challenges effector memory T cells (T-EM) accumulated in the kidney and bone marrow. In the L-NAME/high-salt model, memory T cells of the kidney were predominant sources of interferon- and interleukin-17A, known to contribute to hypertension. L-NAME/high salt increased macrophage and dendritic cell surface expression of CD70 by 3- to 5-fold. Mice lacking CD70 did not accumulate T-EM cells and did not develop hypertension to either high salt or the second angiotensin II challenge and were protected against renal damage. Bone marrow-residing T-EM cells proliferated and redistributed to the kidney in response to repeated salt feeding. Adoptively transferred T-EM cells from hypertensive mice homed to the bone marrow and spleen and expanded on salt feeding of the recipient mice. Conclusions: Our findings illustrate a previously undefined role of CD70 and long-lived T-EM cells in the development of blood pressure elevation and end-organ damage that occur on delayed exposure to mild hypertensive stimuli. Interventions to prevent repeated hypertensive surges could attenuate formation of hypertension-specific T-EM cells.1181233124

Primary squamous cell carcinoma of the pancreas: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Primary squamous cell carcinoma of the pancreas is a rare tumor with poor prognosis and is found in the literature only as case reports. The optimal management course remains poorly defined. We present a case of primary basaloid squamous cell carcinoma of the pancreas metastatic to the liver, which was treated with surgery and systemic chemotherapy. Our patient survived for 15 months: the longest survival reported in the literature to date.</p> <p>Case presentation</p> <p>A 70-year-old Caucasian man presented to hospital with a three-month history of weight loss, pruritus and icterus. Imaging studies confirmed the presence of an operable mass lesion in the head of the pancreas. Following a pancreaticoduodenectomy, histology results led us to make a diagnosis of squamous cell carcinoma. Postoperative restaging showed multiple metastases in the liver. He underwent palliative systemic chemotherapy with cisplatin and 5-fluorouracil achieving partial response and an excellent quality of life. He then went on to start second-line chemotherapy, but unfortunately died of sepsis soon thereafter.</p> <p>Conclusions</p> <p>This case report emphasizes that achievement of a worthwhile objective and symptomatic palliative response is possible using platinum-based chemotherapy in squamous cell carcinoma of the pancreas.</p