PubMed Health⌕ Search

Biomedical subjects

C Regnard

Publications and source records attributed to C Regnard.

At least 19 recordsLinked to original sources
PubMed2000

Polyglutamylation of nucleosome assembly proteins.

Polyglutamylation is an original posttranslational modification, discovered on tubulin, consisting in side chains composed of several glutamyl units and leading to a very unusual protein structure. A monoclonal antibody directed against glutamylated tubulin (GT335) was found to react with other proteins present in HeLa cells. After immunopurification on a GT335 affinity column, two prominent proteins of approximately 50 kDa were observed. They were identified by microsequencing and mass spectrometry as NAP-1 and NAP-2, two members of the nucleosome assembly protein family that are implicated in the deposition of core histone complexes onto chromatin. Strikingly, NAP-1 and NAP-2 were found to be substrates of an ATP-dependent glutamylation enzyme co-purifying on the same column. We took advantage of this property to specifically label and purify the polyglutamylated peptides. NAP-1 and NAP-2 are modified in their C-terminal domain by the addition of up to 9 and 10 glutamyl units, respectively. Two putative glutamylation sites were localized for NAP-1 at Glu-356 and Glu-357 and, for NAP-2, at Glu-347 and Glu-348. These results demonstrate for the first time that proteins other than tubulin are polyglutamylated and open new perspectives for studying NAP function.

Amino Acid Sequence↗
PubMed1999

Tubulin polyglutamylase: isozymic variants and regulation during the cell cycle in HeLa cells.

Polyglutamylation is a posttranslational modification of tubulin that is very common in neurons and ciliated or flagellated cells. It was proposed to regulate the binding of microtubule associated proteins (MAPs) and molecular motors as a function of the length of the polyglutamyl side-chain. Though much less common, this modification of tubulin also occurs in proliferating cells like HeLa cells where it is associated with centrioles and with the mitotic spindle. Recently, we partially purified tubulin polyglutamylase from mouse brain and described its enzymatic properties. In this work, we focused on tubulin polyglutamylase activity from HeLa cells. Our results support the existence of a tubulin polyglutamylase family composed of several isozymic variants specific for alpha- or beta-tubulin subunits. In the latter case, the specificity probably also concerns the different beta-tubulin isotypes. Interestingly, we found that tubulin polyglutamylase activity is regulated in a cell cycle dependent manner and peaks in G(2)-phase while the level of glutamylated tubulin peaks in mitosis. Consistent results were obtained by treating the cells with hydroxyurea, nocodazole or taxotere. In particular, in mitotic cells, tubulin polyglutamylase activity was always low while glutamylation level was high. Finally, tubulin polyglutamylase activity and the level of glutamylated tubulin appeared to be inversely related. This paradox suggests a complex regulation of both tubulin polyglutamylase and the reverse deglutamylase activity.

Animals↗
PubMed1998

Tubulin polyglutamylase: partial purification and enzymatic properties.

In this work, we report on a novel enzyme, tubulin polyglutamylase, which catalyzes the posttranslational formation of polyglutamyl side chains onto alpha- and beta-tubulin. The length of the polyglutamyl side chain regulates the interaction between tubulin and various microtubule-associated proteins. We first developed an in vitro glutamylation assay. Activity measured in brain, a tissue particularly enriched with glutamylated tubulin, decreases during postnatal development. Thus, brains from 3-day-old mice were chosen as the starting material, and the enzyme was purified approximately 1000-fold. Its Mr was estimated to be 360K and its sedimentation coefficient 10 s. The enzyme catalyzes the MgATP-dependent addition of l-glutamate onto tubulin subunits. Microtubules are much better substrates than unpolymerized tubulin, and the reaction is very specific for glutamate, other amino acids or glutamate analogues not being substrates. Moreover, glutamyl units are added sequentially onto tubulin, leading to progressive elongation of the polyglutamyl side chains. Side chains of one to six or seven glutamyl units were obtained with microtubules, whereas much longer side chains (up to 15-20 units) were formed with unpolymerized tubulin. Interestingly, such very long polyglutamyl side chains were recently detected in some situations in vivo.

Adenosine Triphosphate↗
PubMed1996

[Microtubules: functional polymorphisms of tubulin and associated proteins (structural and motor MAP's)].

In neuronal cells, microtubules are built from a very large number of alpha- and beta-tubulin variants. This diversity is due to the expression of a multigene family and to a combination of several original posttranslational modifications. Similarly, structural and motor microtubule-associated proteins, which regulate the assembly of microtubules, the modeling of their network and the mediation of their functions, are also very heterogeneous. As a consequence, mixing of these two protein polymorphisms leads to the formation of functionally-distinct microtubules. We have shown that polyglutamylation, the major posttranslational modification of neuronal tubulin, was used as a progressive regulator in the binding of structural and motor microtubule-associated proteins, in modulating gradually the conformation of the tubulin carboxy-terminal domain, playing thus a crucial role in microtubule dynamics.

Animals↗
PubMed1994

Dealing with anger in a patient or relative: a flow diagram.

Anger from any cause can block effective interaction between the patient and the carer. It has many possible causes, which may be rational, irrational (i.e. inappropriate or misdirected) or pathological. This flow diagram suggests strategies for handling anger in patients with advanced disease.

Anger↗
PubMed1994

Breaking bad news--a flow diagram.

Breaking bad news is neither an easy nor a popular task. Properly handled, however, it can be given in a positive way that the individual can both accept and understand. There may be a range of emotions and concerns following the telling of bad news. These need to be explored and worked through with each individual. This flow diagram describes the steps in this important process.

Adaptation, Psychological↗
PubMed1994

Handling difficult questions in palliative care--a flow diagram.

Patients with advanced disease ask many difficult questions, some of which have painful answers, some of which have answers which contain uncertainty, and some of which have no answers. They should be able to ask their questions in an environment that allows them to disclose their true worries, have the opportunity to talk them through, and look for options. Health professionals need to develop the relevant skills to help patients and their families to disclose and discuss difficult issues, while handling their own emotions.

Adaptation, Psychological↗
PubMed1993

Managing family problems in advanced disease--a flow diagram.

The interaction between patient, family and professional team can sometimes make difficult situations worse rather than better. This flow diagram attempts to clarify the process by which a professional assesses situations and suggests ways in which people can gain understanding about their difficulties. Once everyone has a greater understanding of what is or is not happening, the diagram points to ways in which professionals can use questions to help patient and family create a solution that is workable both for them and for the professionals.

Adaptation, Psychological↗
PubMed1993

Eliciting the current problems of the patient with cancer--a flow diagram.

The assessment of a patient is an integral part of clinical management. It should be conducted in a way which maximizes the likelihood of patients disclosing all their main problems, whether physical, social or psychological in nature. Unfortunately, professional carers can be uncertain of their ability to do this. This flow diagram leads the carer through key points in the assessment interview.

Algorithms↗
PubMed1993

Managing the anxious patient with advancing disease--a flow diagram.

Anxiety can be one aspect of the psychological reaction to cancer and may be present at a clinical level. It can hinder or even prevent the diagnosis and management of other problems and when it develops into an anxiety state it can be disabling. This flow diagram describes the key clinical decisions involved in diagnosing and helping a patient troubled with anxiety.

Algorithms↗
PubMed1993

Handling the withdrawn patient--a flow diagram.

The withdrawn patient challenges effective communication. Some patients are naturally introverted or quiet, but for others the withdrawal represents a change with many possible causes. This flow diagram describes the approach to a withdrawn patient and outlines management.

Algorithms↗