Living on the edge: the role of Atgolgin-84A at the plant ER-Golgi interface

The plant Golgi apparatus is responsible for the processing of proteins received from the endoplasmic reticulum (ER) and their distribution to multiple destinations within the cell. Golgi matrix components, such as golgins, have been identified and suggested to function as putative tethering factors to mediate the physical connections between Golgi bodies and the ER network. Golgins are proteins anchored to the Golgi membrane by the C-terminus either through transmembrane domains or interaction with small regulatory GTPases. The golgin N-terminus contains long coiled-coil domains, which consist of a number of α-helices wrapped around each other to form a structure similar to a rope being made from several strands, reaching into the cytoplasm. In animal cells, golgins are also implicated in specific recognition of cargo at the Golgi.Here, we investigate the plant golgin Atgolgin-84A for its subcellular localization and potential role as a tethering factor at the ER-Golgi interface. For this, fluorescent fusions of Atgolgin-84A and an Atgolgin-84A truncation lacking the coiled-coil domains (Atgolgin-84AΔ1-557) were transiently expressed in tobacco leaf epidermal cells and imaged using high-resolution confocal microscopy. We show that Atgolgin-84A localizes to a pre-cis-Golgi compartment that is also labelled by one of the COPII proteins as well as by the tether protein AtCASP. Upon overexpression of Atgolgin-84A or its deletion mutant, transport between the ER and Golgi bodies is impaired and cargo proteins are redirected to the vacuole. LAY DESCRIPTION: The Golgi apparatus is a specialised compartment found in mammalian and plant cells. It is the post office of the cell and packages proteins into small membrane boxes for transport to their destination in the cell. The plant Golgi apparatus consist of many separate Golgi bodies and is responsible for the processing of proteins received from the endoplasmic reticulum (ER) and their distribution to multiple destinations within the cell. Specialised proteins called golgins have been suggested to tether Golgi bodies and the ER. Here we investigate the plant golgin Atgolgin-84A for its exact within the Golgi body and its potential role as a tethering factor at the ER-Golgi interface. For this, we have fused Atgolgin-84A with a fluorescent protein from jellyfish and we are producing this combination in tobacco leaf cells. This allows us to see the protein using laser microscopy. We show that Atgolgin-84A localises to a compartment between the ER and Golgi that is also labelled by the tether protein AtCASP. When Atgolgin-84A is produced in high amounts in the cell, transport between the ER and Golgi bodies is inhibited and proteins are redirected to the vacuole.

Amyloid precursor protein, lipofuscin accumulation and expression of autophagy markers in aged bovine brain

Background

Autophagy is a highly regulated process involving the bulk degradation of cytoplasmic macromolecules and organelles in mammalian cells via the lysosomal system. Dysregulation of autophagy is implicated in the pathogenesis of many neurodegenerative diseases and integrity of the autophagosomal - lysosomal network appears to be critical in the progression of aging. Our aim was to survey the expression of autophagy markers and Amyloid precursor protein (APP) in aged bovine brains. For our study, we collected samples from the brain of old (aged 11–20 years) and young (aged 1–5 years) Podolic dairy cows. Formalin-fixed and paraffin embedded sections were stained with routine and special staining techniques. Primary antibodies for APP and autophagy markers such as Beclin-1 and LC3 were used to perform immunofluorescence and Western blot analysis.

Results

Histologically, the most consistent morphological finding was the age-related accumulation of intraneuronal lipofuscin. Furthermore, in aged bovine brains, immunofluorescence detected a strongly positive immunoreaction to APP and LC3. Beclin-1 immunoreaction was weak or absent. In young controls, the immunoreaction for Beclin-1 and LC3 was mild while the immunoreaction for APP was absent. Western blot analysis confirmed an increased APP expression and LC3-II/LC3-I ratio and a decreased expression of Beclin-1 in aged cows.

Conclusions

These data suggest that, in aged bovine, autophagy is significantly impaired if compared to young animals and they confirm that intraneuronal APP deposition increases with age.

Age-Related Changes in Skeletal Muscle of Cattle

Sarcopenia, the age-related loss of muscle mass and strength, is a multifactorial condition that represents a major healthcare concern for the elderly population. Although its morphologic features have been extensively studied in humans, animal models, and domestic and wild animals, only a few reports about spontaneous sarcopenia exist in other long-lived animals. In this work, muscle samples from 60 healthy Podolica-breed old cows (aged 15-23 years) were examined and compared with muscle samples from 10 young cows (3-6 years old). Frozen sections were studied through standard histologic and histoenzymatic procedures, as well as by immunohistochemistry, immunofluorescence, and Western blot analysis. The most prominent age-related myopathic features seen in the studied material included angular fiber atrophy (90% of cases), mitochondrial alterations (ragged red fibers, 70%; COX-negative fibers, 60%), presence of vacuolated fibers (75%), lymphocytic (predominantly CD8+) inflammation (40%), and type II selective fiber atrophy (40%). Immunohistochemistry revealed increased expression of major histocompatibility complex I in 36 cases (60%) and sarcoplasmic accumulations of β-amyloid precursor protein-positive material in 18 cases (30%). In aged cows, muscle atrophy was associated with accumulation of myostatin. Western blot analysis indicated increased amount of both proteins-myostatin and β-amyloid precursor protein-in muscles of aged animals compared with controls. These findings confirm the presence of age-related morphologic changes in cows similar to human sarcopenia and underline the possible role of amyloid deposition and subsequent inflammation in muscle senescence.

Functional characterization of the ectopically expressed olfactory receptor 2AT4 in human myelogenous leukemia

The olfactory receptor (OR) family was found to be expressed mainly in the nasal epithelium. In the last two decades members of the OR family were detected to be functional expressed in different parts of the human body such as in liver, prostate or intestine cancer cells. Here, we detected the expression of several ORs in the human chronic myelogenous leukemia (CML) cell line K562 and in white blood cells of clinically diagnosed acute myeloid leukemia (AML) patients by RT-PCR and next-generation sequencing. With calcium-imaging, we characterized in greater detail the cell biological role of one OR (OR2AT4) in leukemia. In both cell systems, the OR2AT4 agonist Sandalore-evoked strong Ca²⁺ influx via the adenylate cyclase-cAMP-mediated pathway. The OR2AT4 antagonist Phenirat prevented the Sandalore-induced intracellular Ca²⁺ increase. Western blot and flow cytometric experiments revealed that stimulation of OR2AT4 reduced the proliferation by decreasing p38-MAPK phosphorylation and induced apoptosis via phosphorylation of p44/42-MAPK. Furthermore, Sandalore increased the number of hemoglobin-containing cells in culture. We described for the first time an OR-mediated pathway in CML and AML that can regulate proliferation, apoptosis and differentiation after activation. This mechanism offers novel therapeutic options for the treatment of AML.

Increased expression of Noga-A in ALS muscle biopsies is not unique for this disease

Nogo (RTN4) belongs to the reticulon (RTN) family of integral membrane proteins. RTN4A (Nogo-A), RTN4B (Nogo-B) and RTN4C (Nogo-C) are isoforms of RTN4. In the gastrocnemius muscle of transgenic mice bearing an SOD1 mutation ("ALS model"), increased Nogo-A mRNA and protein was reported, and similar changes were reported in muscle biopsies of patients with amyotrophic lateral sclerosis (ALS) but not with peripheral neuropathy or primary muscle diseases, leading to the proposal that Nogo-A in skeletal muscle is a new specific molecular marker of ALS. Here we report, based on studies of muscle biopsies from patients with ALS, peripheral neuropathies, polymyositis, dermatomyositis and morphologically nonspecific myopathies that, in addition of strong Nogo-A immunoreactivity within apparently-denervated small angular fibers in ALS and peripheral neuropathies, Nogo-A was strongly immunoreactive within desmin-positive regenerating muscle fibers in various myopathies, and its expression on immunoblots was increased in all those neuromuscular diseases. In conclusion, we have found that the presence of Nogo-A in diseased human muscle biopsies is not limited to ALS.

Mutations in the 1A domain of keratin 9 in patients with epidermolytic palmoplantar keratoderma

Epidermolytic palmoplantar keratoderma is an autosomal dominant skin disorder characterized by hyperkeratosis of the palms and soles. Ultrastructurally the disease exhibits abnormal keratin filament networks and tonofilament clumping like that found in the keratin disorders of epidermolysis bullosa simplex and epidermolytic hyperkeratosis. The disease has been mapped to chromosome 17q11-q23 in the region of the type 1 keratin gene locus and more recently mutations have been found in the palmoplantar specific keratin, keratin 9. We have analyzed six unrelated incidences of epidermolytic palmoplantar keratoderma for mutations in their keratin 9 genes. In two of these, we have identified mutations that alter critical residues within the highly conserved helix initiation motif at the beginning of the rod domain of keratin 9. In a three-generation Middle Eastern kindred we found a C to T transition at codon 162 that results in an arginine to tryptophan substitution at position 10 of the 1A alpha-helical domain, thus confirming this codon as a hot spot for mutation in keratin 9. The other mutation found involves a T to C transition at codon 167 that results in the expression of a serine residue in place of the normal leucine at position 15 of the 1A segment and is the first documentation of this mutation in this gene. The identification of these substitutions extends the current catalog of disease causing mutations in keratin 9.

Mutations in the rod domain of keratin 2e in patients with ichthyosis bullosa of Siemens

Ichthyosis bullosa of Siemens (IBS) is an autosomal dominant skin disorder that resembles epidermolytic hyperkeratosis (EHK). We have identified mutations in two families originally diagnosed with EHK and in four families diagnosed with IBS at the same codon in the highly conserved carboxy terminal of the rod domain of keratin 2e, thus revealing a mutational hot spot. Our results allow a differential diagnosis to be made between IBS and EHK at the genetic level and we suggest that patients diagnosed with EHK, but lacking keratin K1 or K10 mutations, should be re-examined for mutations in their K2e genes.

9-Anilinoacridines as potential antileishmanial agents

A number of 1'-substituted 9-anilinoacridines were evaluated for their activities against promastigote and amastigote forms of Leishmania major and for their toxicities to human Jurkat leukemia cells. Several compounds possessing 1'-NH-alkyl substituents produced more than 80% growth inhibition of macrophage-infected L. major amastigotes at or below a concentration of 1 microM. 1'-Hexylamino-9-anilinoacridine (compound 14) was the least toxic compound to human Jurkat cells, while it retained strong antileishmanial activity. There was a general trend for the more lipophilic compounds to show the greatest antileishmanial activity, whereas 3,6-di-NH2 substitution of the acridine nucleus reduced or eliminated activity. Some structure-activity relationships of the various compounds are discussed.

Inhibitors of lipoxygenase have antiproliferative effects on P815 murine mastocytoma cells

The effect of a variety of inhibitors of prostaglandin synthase, lipoxygenase and phospholipase on the growth of P815 murine mastocytoma cells was examined. Only lipoxygenase inhibitors substantially reduced growth, presumably by inhibiting the production of arachidonic acid metabolites rather than causing arachidonate accumulation since excess arachidonic acid did not reverse growth inhibition. Evidence is presented that production of leukotrienes B4, C4, D4 or E4 was not involved. Other metabolites of arachidonic acid were not excluded. A role for lipoxygenase in growth signal transduction in these and other cells is suggested.

Cost-effectiveness and reimbursement in patient care

The recent collapse of the previously effective coalition of the federal government, universities and medical schools, the pharmaceutical industry, and third-party payers has resulted in the current crisis in funding of clinical trials. The reduced financial support for clinical research comes at a time when a number of new investigational therapies offer the promise of better medical care for patients with life-threatening diseases. Controversy exists regarding the role of physicians in encouraging federal support for clinical research and third-party reimbursement for patient care for patients on clinical trials. Some believe the physician should take an activist role on the issues in general, while others believe that the physician should focus on protecting the interests of individual patients by acting as the patient's agent. Many difficult choices lie ahead for society as a whole in determining what percentage of its health-care budget will be allocated for clinical research, who will pay for patient-care costs of patients in clinical trials, and how this relatively limited resource should be distributed among the population at large. Case-management programs are one attempt to monitor and control health-care costs, but in many instances case management has been used to determine if patients are enrolled in clinical research trials and to disallow coverage for other than standard patient care.

Monitoring of the dilution rate during continuous in vivo blood sampling with a double lumen catheter

A simple and non-destructive method for monitoring the dilution rate during continuous blood sampling is described. When the dilution rate is not constant, the proposed method based on electrical resistivity measurement provides a correction factor for further analysis.

Determination of insulin requirements in brittle diabetic patients by the artificial pancreas

An extracorporeal system (called the artificial pancreas) infused insulin and/or glucose at rates regulated by feedback control of the continuously monitored blood glucose. This system was capable of restoring the circadian blood glucose profile of 11 brittle diabetics to within a physiologic range. These patients made two stays of one week each in the hospital, during which the M-value and the MAGE index (used as indexes of blood glucose control and of glycemic fluctuations) were measured. The first stay was just before their connection to the artificial pancreas, while the patients were being given their usual insulin dosage; the second stay occurred one to nine months later. The day after connection of the artificial pancreas, the patients received a new insulin regimen, calculated according to the daily insulin profile infused by the artificial pancreas, consisting of two daily injections of a mixture of short-acting and intermediate-acting insulins. This regimen was essentially characterized by an increased proportion of regular insulin in the daily dose of from 31.2 ± 5.8 per cent (mean ± S.E.M.) before to 56.1 ± 3.0 per cent after artificial pancreas, p < 0.01, and a reduction of the percentage of the dose given in the morning of from 68.1 ± 5.9 to 52.6 ± 2.8 per cent, p < 0.025. These changes of insulin dosage caused a noticeable decrease of the M-value, from 69.5 ± 8 to 53.1 ± 4.4 (p < 0.02), but the MAGE index was not significantly affected (187 ± 20 versus 162 ± 14). Thus, the artificial pancreas could be helpful in the clinical management of brittle diabetics by providing a more precise estimate of the patient's insulin needs (particularly those of short-acting insulin), leading to a better control of blood glucose.