praja2 regulates KSR1 stability and mitogenic signaling

The kinase suppressor of Ras 1 (KSR1) has a fundamental role in mitogenic signaling by scaffolding components of the Ras/MAP kinase pathway. In response to Ras activation, KSR1 assembles a tripartite kinase complex that optimally transfers signals generated at the cell membrane to activate ERK. We describe a novel mechanism of ERK attenuation based on ubiquitin-dependent proteolysis of KSR1. Stimulation of membrane receptors by hormones or growth factors induced KSR1 polyubiquitination, which paralleled a decline of ERK1/2 signaling. We identified praja2 as the E3 ligase that ubiquitylates KSR1. We showed that praja2-dependent regulation of KSR1 is involved in the growth of cancer cells and in the maintenance of undifferentiated pluripotent state in mouse embryonic stem cells. The dynamic interplay between the ubiquitin system and the kinase scaffold of the Ras pathway shapes the activation profile of the mitogenic cascade. By controlling KSR1 levels, praja2 directly affects compartmentalized ERK activities, impacting on physiological events required for cell proliferation and maintenance of embryonic stem cell pluripotency.

TBP-1 protects the human oncosuppressor p14ARF from proteasomal degradation

The p14ARF tumor suppressor is a key regulator of cellular proliferation, frequently inactivated in human cancer. The mechanisms that regulate alternative reading frame (ARF) turnover have been obscure for long time, being ARF a relatively stable protein. Recently, it has been described that its degradation depends, at least in part, on the proteasome and that it can be subjected to N-terminal ubiquitination. We have previously reported that ARF protein levels are regulated by TBP-1 (Tat-Binding Protein 1), a multifunctional protein, component of the regulatory subunit of the proteasome, involved in different cellular processes. Here we demonstrate that the stabilization effect exerted by TBP-1 requires an intact N-terminal 39 amino acids in ARF and occurs independently from N-terminal ubiquitination of the protein. Furthermore, we observed that ARF can be degraded in vitro by the 20S proteasome, in the absence of ubiquitination and this effect can be counteracted by TBP-1. These observations seem relevant in the comprehension of the regulation of ARF metabolism as, among the plethora of cellular ARF's interactors already identified, only NPM/B23 and TBP-1 appear to be involved in the control of ARF intracellular levels.

First genetic analysis of lattice corneal dystrophy type I in a family from Bulgaria

PURPOSE

To report a new family belonging to a previously non-investigated geographic are a with a rare form of lattice corneal dystrophy (LCD).

METHODS

Detailed ophthalmologic analysis was carried out on a Bulgarian woman, enrolled for perforating keratoplasty. In order to obtain a final diagnosis both histology and genetic analysis were performed.

RESULTS

Upon transplantation, histologic analysis of the dystrophic cornea revealed the typical staining pattern and amyloid deposits of lattice corneal dystrophies. Genetic analysis of the subject and her daughter confirmed the presence of an autosomal dominant R124C mutation within exon 4 of the BIGH3 gene, encoding for keratoepithelin, while showing no abnormalities in her son.

CONCLUSIONS

The identification of this mutation allows the unambiguous classification of this corneal dystrophy as LCD type I. A first case of LCD I in a family from Eastern Europe could help to better clarify the molecular epidemiology of the disease.

Acute pancreatitis with Purtscher's retinopathy: case report and review of the literature

The case is described of a 32-year-old man suffering from alcoholism who came to the Emergency Unit with vomiting, fever and sharp epigastric pain irradiating to the chest and upper abdomen. A diagnosis of acute pancreatitis was made after high amylase and lipase levels were observed and the results of computed tomography scan revealed images typical of acute pancreatitis. Findings upon admission and after the initial 48 hours did not correlate with a severe or complicated course according to Ranson's criteria. On the third day after admission he suddenly developed decreased vision. A fluorescein angiogram showed arteriolar occlusion, retinal and choriocapillary ischaemia. Purtscher's retinopathy was suspected. After 4 weeks, the patient had recovered from acute pancreatitis, ophthalmoscopic examination showed normal results, and visual acuity had almost returned to normal. Activation of complement in acute pancreatitis could account for many haematologic acute disorders due to leucocyte emboli or other complement-mediated aggregates. Coagulation abnormalities may range from isolated intravascular thrombosis to severe disseminated intravascular coagulation. Purtscher's retinopathy, due to microembolizations in the choroidal and retinal arterioles, should be included among the various systemic effects of acute pancreatitis. This visual disorder is a rare systemic manifestation of acute pancreatitis which was not correlated to a severe or complicated clinical course. Treatment of these ocular complications remains to be established and outcome, therefore, depends upon resolution of the pancreatic disease.

Trans-scleral krypton laser cyclophotocoagulation: our experience of its use on patients with neovascular glaucoma

Trans-scleral cyclophotocoagulation is an efficacious method in neovascular glaucoma (NVG) treatment. We have used it with krypton laser on 12 eyes of 12 patients affected by NVG with algetic symptoms. Six months after treatment, intraocular pressure was down enough for the pain to disappear. Executional simplicity and the possibility of modulating the intensity of the treatment are grounds for the encouragement of the technique's use in NVG.

Circadian rhythm of T-lymphocyte subsets, cortisol and cyclosporin in kidney-transplanted subjects

The present study deals with the 24-h changes in circulating lymphocyte subpopulations in eight subjects with kidney grafts established for 2 to 5 years and treated with cyclosporin. The control group consisted of ten age-matched clinically healthy subjects. The chronobiological analysis of time series documented that the circadian rhythm of T-lymphocyte subsets is undetectable in transplanted subjects. Cortisol rhythmicity persists, however, suggesting that the abolition of T-cell rhythmicity is not attributable to a desynchronisation of the adrenal cycle. Even though the therapy was combined with prednisolone, the abrogation of rhythmicity for T-lymphocyte subpopulations seems to be related to the immunosuppressive action of cyclosporin, as the plasma concentrations of the drug show no periodic variations along the 24-h span. Antirejection therapy of kidney-transplanted subjects could be adjusted so that cyclosporin is given at a time that would promote suppression of T-lymphocytes without altering their rhythmic performance.

[Circadian rhythm of the renin-angiotensin-aldosterone system in subjects with kidney and heart transplants]

The present investigation evaluates the circadian rhythm of renin-angiotensin-aldosterone system (RAAS) in subjects with kidney (KTS) or heart (HTS) transplantation undergoing conventional therapy with prednisone and cyclosporine. RAAS circadian rhythmicity has been compared with the circadian cycle of cortisol as a marker rhythm. The chronobiological exploration has been performed by measuring the circulating levels of plasma renin activity (PRA), plasma aldosterone (PA), and serum angiotensin-converting-enzyme (SACE) and plasma cortisol (PC) in serial samplings collected six times over a 24-h span. Time-qualified levels of plasma cyclosporine (CYCL) have been established. The control group consisted of 10 normal subjects matching in age and sex. Individual data series were analysed by the Cosinor method. The chronobiometric estimates demonstrate the lack of a circadian rhythmicity for PRA, PA and SACE in KTS and HTS. The PC circadian rhythm is demonstrable in KTS, but not in HTS. The abolition of the RAAS circadian rhythm in both KTS and HTS seems to be attributable to the effects exerted by CYCL. The disappearance of the PC circadian rhythm may be due to the prednisone therapy that is administered twice a day in HTS but not in KTS. The asynchronous effects of this drug lead us to suggest that antirejection therapy may be optimized by administering prednisone and cyclosporine according to a chronomodulated scheme.

[24-hour behavior of T-lymphocyte subpopulations in patients with stable heart transplants receiving cyclosporin therapy]

In 10 heart transplanted subjects (HTS) undergoing conventional immunosuppressive cyclosporine therapy, in comparison with 10 normal subjects, the 24 hour patterns of T lymphocyte subpopulations, namely, OKT3 (total T lymphocytes), OKT4 (helper lymphocytes) and OKT8 (cytotoxic or suppressor) in relation to the circadian rhythms for plasma cortisol (marker rhythm) and to circulating levels of cyclosporine were studied. From the collected data, it can be deduced that the OKT3, OKT4, OKT8 subpopulations and the plasma cortisol level show 24-hour non-periodic variations. The lymphocyte subpopulations show a negative correlation with circulating levels of cyclosporine. The negative correlation is "selective" and "delayed" in that it is detectable at particular and non-coinciding hours. Plasma cortisol is also negatively correlated to plasma cyclosporine. Assessing the meaning of the lack of a circadian rhythm of the lymphocyte subpopulation in HTS undergoing conventional cyclosporine therapy, and taking into account the pharmacological time-stage dependency, we can emphasize the idea that the optimization of anti-rejection therapy with cyclosporine may and should be performed as a time-modulated treatment.

"GIANT" macronodular adrenal hyperplasia causing Cushing's syndrome: case report and review of the literature on a clinical distinction of adrenocortical nodular pathology associated with hypercortisolism

Cushing's syndrome (CS) may be sustained by a nodular adrenocortical pathology (NAP) in addition to hyperplastic or neoplastic lesions of adrenal glands. NAP, in turn, may be represented by macronodular (MACRO) or micronodular (MICRO) manifestations. There is debate as to whether the MACRO-NAP and MICRO-NAP represent an expression of the same disorder or relate to distinguishable anatomo-clinical entities. A case of CS sustained by a "giant" MACRO-NAP forced use to review the literature and to analyze the morpho-clinical findings from a statistical viewpoint. Testing procedures were able to significantly dissect some clinical, pathological and hormonal characteristics. The statistical probation clearly indicated that MACRO-NAP and MICRO-NAP causing CS are nosologic entities that can be clinically differentiated via their phenotypic symptomatology.