Systematic analysis of the contribution of c-myc mRNA constituents upon cap and IRES mediated translation.

Fine tuning of c-MYC expression is critical for its action and is achieved by several regulatory mechanisms. The contribution of c-myc mRNA regulatory sequences on its translational control has been investigated individually. However, putative interactions have not been addressed so far.

The structure of the 5'-untranslated region of mammalian poly(A) polymerase-alpha mRNA suggests a mechanism of translational regulation.

Poly(A)polymerase-alpha (PAPOLA) has been the most extensively investigated mammalian polyadenylating enzyme, mainly in regard to its multifaceted post-translational regulation. The possibility of translational regulation of this enzyme was addressed. The transcription start site was mapped and two uORFs, highly conserved among several species, were identified in the 211-bp long, GC-rich, 5' UTR of the PAPOLA mRNA.

Beliefs about the mentally ill: a comparative study between healthcare professionals in Brazil and in Switzerland.

Objective: Little is known in our own as well as in other cultures about the knowledge and prejudices mental health professionals have about mental illness and those affected. We therefore: 1) assessed mental health literacy and general attitudes towards people with mental illness in a sample of Brazilian mental health professionals; 2) compared the outcomes among the different professional groups; and 3) compared the data with a sample of Swiss mental health professionals.

Methods: A questionnaire used to assess knowledge and attitudes towards the mentally ill among mental health professionals in Switzerland was translated into Portuguese.

Expression of oncofetal RNA-binding protein CRD-BP/IMP1 predicts clinical outcome in colon cancer.

The oncofetal CRD-BP/IMP1 RNA binding protein regulates posttranscriptionally a handful of RNA transcripts, implicated in cell adhesion and invadopodia formation and was recently identified as a target of the beta-catenin/Tcf transcription factor that is constitutively activated in colorectal carcinomas (CRCs). The expression of CRD-BP/IMP1 was studied in normal adult intestines and CRCs. In normal mucosa, CRD-BP/IMP1 immunoreactivity was observed in few scattered cells located predominantly at or near the bottom of the crypts, whereas in CRCs the protein was detectable in tumor cells of 50% of the specimens analyzed.

Expression of the RNA-binding protein CRD-BP in brain and non-small cell lung tumors.

The coding region determinant-binding protein (CRD-BP) is an RNA binding protein that recognizes c-myc and IGF-II leader 3 mRNAs as well as the oncofetal H19 RNA. CRD-BP exhibits an oncofetal pattern of expression and has been detected in the majority of colon (81%), breast (58.5%) and sarcoma (73%) tumors.

K562 cell sensitization to 5-fluorouracil- or interferon-alpha-induced apoptosis via cordycepin (3'-deoxyadenosine): fine control of cell apoptosis via poly(A) polymerase upregulation.

K562 cells represent a classical model for the study of drug resistance. Induction of apoptosis is accompanied by concomitant distinct modulations of poly(A) polymerase (PAP) and other proteins involved in mRNA maturation. Recent data suggest the involvement of mRNA stability in the induction of specific apoptosis pathways.

Polyadenylate polymerase enzymatic activity in mammary tumor cytosols: A new independent prognostic marker in primary breast cancer.

Polyadenylate polymerase (PAP) is one of the enzymes involved in the formation of the polyadenylate tail of the 3' end of mRNA. High levels of PAP activity were associated with rapidly proliferating cells. Here we evaluate the prognostic value of PAP activity in breast cancer patients.

Poly(A)polymerase activity levels in breast tumour cytosols.

The enzyme poly(A) polymerase (PAP) catalyses the polyadenylation of mRNA and its activity levels vary within the cell cycle. The levels of activity of this enzyme were measured in the cytosol of breast tumours from 62 untreated patients and compared to clinical prognostic parameters as well as other biological markers. The enzyme levels measured ranged from 3 to 46 units/mg protein.

The polyadenylation inhibitor cordycepin (3'dA) causes a decline in c-MYC mRNA levels without affecting c-MYC protein levels.

Study of the distribution of the poly(A) tail length of c-myc mRNA in several cell lines revealed a distinct, prevailing population with short poly(A) tails, derived through sequential deadenylation. To elucidate the possible in vivo function of this distinct short tailed c-myc mRNA population, the polyadenylation inhibitor cordycepin was used. This resulted in a decline in steady state c-myc mRNA levels with the remaining messenger mostly oligoadenylated.

In vivo generation of 3' and 5' truncated species in the process of c-myc mRNA decay.

It has been demonstrated that the half-life of c-myc mRNA is modulated in response to physiological agents. The elucidation of the decay process and the identification of the critical steps in the in vivo c-myc mRNA degradation pathway can be approached by following the fate of c-myc mRNA under the influence of such factors. IFN-alpha was the factor used to modulate c-myc mRNA half-life in HeLa 1C5 cells, a stable clone derived from HeLa cells.

Poly(A) metabolism and aging: a current view.

Polyadenylation of mRNA is a key step in post-transcriptional control of gene expression. Therefore, age-dependent changes in poly(A) synthesis have to play a crucial role in the course of cellular aging. In this review, the importance of the signal sequence, poly(A), in determining mRNA stability and intracellular distribution of mRNA during aging is discussed.

Patterns of adenosine deaminase, ecto-5'-nucleotidase, poly(A)polymerase and surface light chain expression in chronic lymphocytic leukemias.

The levels of activity of three enzymes have been measured in the circulating malignant lymphocytes of 47 patients with B chronic lymphocytic leukemia (CLL). These were the purine degradative enzymes, adenosine deaminase (ADA) and ecto-5'-nucleotidase (5'NT) and the enzyme responsible for the polyadenylation of mRNA, poly(A) polymerase. The patterns of activity of the above enzymes and the expression of surface immunoglobulin light chains were examined.

Relation between the activity of poly(A)polymerase and the levels of protein synthesis in the lymphocytes of patients with chronic lymphocytic leukemia.

The activity levels of the enzyme poly(A)polymerase and the levels of protein synthesis primed by endogenous messenger RNA (mRNA) as well as polyuridylic acid, poly(U) directed polyphenylalanine synthesis, were determined in lymphocytic extracts from 17 patients with chronic lymphocytic leukemia of the B cell type. The enzyme activity values have not been found to correlate with the poly(U)-protein synthesis, whereas a positive linear correlation has been established between the activity levels of poly(A)polymerase and the endogenous mRNA-primed protein synthesis (r = 0.735, p less than 0.

A colorimetric assay for the determination of 5'-nucleotidase activity.

A rapid, simple, quantitative and sensitive assay for the determination of 5'-nucleotidase has been developed. The method can be applied to both soluble and membrane bound forms of the leukocyte enzyme. Enzyme activity is determined by colorimetric estimation of NH3 released from adenosine, the product of 5'-nucleotidase activity in the presence of adenosine deaminase.

Increase in the levels of activity of polyadenylic acid-metabolizing enzymes following phytohaemagglutinin stimulation of human lymphocytes.

Increased levels of soluble activity of all three enzymes involved in polyadenylic acid metabolism were measured in PHA-stimulated versus normal lymphocytes. Poly(A)-polymerase and poly(A)-exonuclease values increased significantly (from 25.7 +/- 4.

Polyadenylic acid polymerase activity in normal and leukemic human leukocytes.

Soluble polyadenylic acid [poly(A)] polymerase and poly(A) nucleases content of normal human blood lymphocytes and leukemic blood cell populations was determined. Blood lymphocytes from seven normal individuals were used as controls. Leukemic cells were obtained from 69 patients with various types of acute and chronic leukemias.