Association of HAP1 isoforms with a unique cytoplasmic structure

HAP1 is a neural protein and interacts with the Huntington's disease protein huntingtin. There are at least two HAP1 isoforms, HAP1-A and HAP1-B, which have different C-terminal amino acid sequences. Here we report that both HAP1 isoforms associate with a unique cytoplasmic structure in neurons of rat brain. The HAP1-immunoreactive structure appears as an inclusion that is an oval mass of electron-dense material, 0.5-3 microm in diameter, containing many curvilinear or ring-shaped segments, and often containing electron-lucent cores. This structure is very similar to those previously termed the stigmoid body, nematosome, or botrysome. Transfection of cell lines with cDNA encoding HAP1-A, but not HAP1-B, resulted in similar HAP1-immunoreactive inclusions in the cytoplasm, suggesting that HAP1-A is essential to the formation of this structure. Yeast two-hybrid and transfection studies show that both HAP1-A and HAP1-B can self-associate, implying that native HAP1 in the cytoplasmic inclusion may be a heteromultimer of HAP1-A and HAP1-B. Coexpression of HAP1-A and HAP1-B in human embryonic kidney 293 cells demonstrates that the ratio of the expressed HAP1-A to HAP1-B regulates the formation of HAP1-associated inclusions. We propose that HAP1 isoforms are involved in the formation of HAP1-immunoreactive inclusions in the neuronal cytoplasm.

[Role of paraventricular nucleus in pressor response induced by dorsol part of midbrain periaqeductal gray stimulation]

Experiments were carried out on male SD rats anesthetized with urethane (700 mg/kg) and chloralose (35 mg/kg). The results were as follows: (1) The pressor response could be elicited by electrical stimulation of dorsol part of midbrain periaqueductal gray (dPAG) for 5 s every 5 min. The pressor response for each series of dPAG stimulation within 50 min was constant. This pressor response could be decreased by electrolytic cauterization of paraventricular (PVN) area, but unaffected by electrolytic lesion of fornix, anterior hypothalamic area, nucleus dorsomedialis hypothalami and nucleus ventromedicalis hypothalami. (2) Microinjection of an AVP-V1 receptor antagonist (CH2)5 [Tyr(Me)2AVP] (each side 0.1 nmol/0.1 microliter) into the bilateral rostral ventrolateral medulla (rVLM) partially inhibited the pressor response induced by PVN stimulation or by microinjection of D,L-homocysteric acid (DLH) (0.1 mol/0.2 microliter) into the PVN, but the mean artrtial pressure (MBP) and heart rate (HR) did not show any change when an AVP-V1 receptor antagonist or DLH was only used. (3) Microinjection of an AVP-V1 receptor antagonist into the bilateral rVLM partially inhibited the pressor response induced by dPAG stimulation. Therefore it is suggested that the effect of vasopression (AVP) released from PVN on the pressor response induced by dPAG stimulation is partly mediated by activation of AVP-V1 receptor in the rVLM.

The cellular and subcellular localization of huntingtin-associated protein 1 (HAP1): comparison with huntingtin in rat and human

The cellular and subcellular distribution of HAP1 was examined in rat brain by light and electron microscopic immunocytochemistry and subcellular fractionation. HAP1 localization was also determined in human postmortem tissue from control and Huntington's disease (HD) cases by light microscopic immunocytochemistry. At the cellular level, the heterogeneity of HAP1 expression was similar to that of huntingtin; however, HAP1 immunoreactivity was more widespread. The subcellular distribution of HAP1 was examined using immunogold electron microscopy. Like huntingtin, HAP1 is a cytoplasmic protein that associates with microtubules and many types of membranous organelles, including mitochondria, endoplasmic reticulum, tubulovesicles, endosomal and lysosomal organelles, and synaptic vesicles. A quantitative comparison of the organelle associations of HAP1 and huntingtin showed them to be almost identical. Within HAP1-immunoreactive neurons in rat and human brain, populations of large and small immunoreactive puncta were visible by light microscopy. The large puncta, which were especially evident in the ventral forebrain, were intensely HAP1 immunoreactive. Electron microscopic analysis revealed them to be a type of nucleolus-like body, which has been named a stigmoid body, that may play a role in protein synthesis. The small puncta, less intensely labeled, were primarily mitochondria. These results indicate that the localization of HAP1 and huntingtin is more similar than previously appreciated and provide further evidence that HAP1 and huntingtin have localizations consistent with roles in intracellular transport. Our data also suggest, however, that HAP1 is not present in the abnormal intranuclear and neuritic aggregates containing the N-terminal fragment of mutant huntingtin that are found in HD brains.

Distribution of the B33 CTG repeat polymorphism in a subtype of schizophrenia

Clinical evidence for a dominant mode of inheritance and anticipation in periodic catatonia, a distinct subtype of schizophrenia, suggests that trinucleotide repeat expansions may be involved in the aetiology of this disorder. Since genes with triplet repeats are putative canditates for causing schizophrenia, we have analysed the polymorphic B33 CTG repeat locus on chromosome 3 in 45 patients with periodic catatonia and 43 control subjects. The B33 CTG repeat locus was highly polymorphic, but all alleles in both the patient and control groups had repeat lengths within the normal range. We conclude that susceptibility to periodic catatonia is not influenced by variation at the B33 CTG repeat locus. Nevertheless, that periodic catatonia displays dominant inheritance and anticipation, characteristic of genetic disorders involving trinucleotide repeats, justifies further screening for triplet repeat expansions in this illness.

A human HAP1 homologue. Cloning, expression, and interaction with huntingtin

Huntington's disease (HD) is caused by the expansion of a glutamine repeat in the protein huntingtin. The expanded glutamine repeat is thought to mediate a gain of function by causing huntingtin to abnormally interact with other proteins. We previously identified a rat huntingtin-associated protein (HAP1) that binds to huntingtin; HAP1 binds more tightly to huntingtin with an expanded glutamine repeat than to wild type huntingtin. Identification of the human homologue of HAP1 is necessary for investigation of the potential role of HAP1 in HD pathology. Here, we report the cloning of a human HAP1 homologue (hHAP) that shares 62% identity with rat HAP1 over its entire sequence and 82% amino acid identity in the putative huntingtin-binding region. The hHAP gene encodes a 4.1-kilobase transcript and a 75-kDa protein which are specifically expressed in human brain tissues. Its expression in Huntington's disease brains is reduced in parallel with a decreased expression of huntingtin. While two isoforms of rat HAP1 are expressed at similar levels in rat brain, only a single major form of hHAP is found in primate brains. In vitro binding, immunoprecipitation, and coexpression studies confirm the interaction of hHAP with huntingtin. The in vitro binding of hHAP to huntingtin is enhanced by lengthening the glutamine repeat. Despite similar binding properties of rat HAP1 and hHAP, differences in the sequences and expression of hHAP may contribute to a specific role for its interaction with huntingtin in humans.

Aggregation of N-terminal huntingtin is dependent on the length of its glutamine repeats

Huntington's disease (HD) is caused by expansion of a glutamine repeat in huntingtin. Mutant huntingtin contains 36-55 repeats in adult HD patients and >60 repeats in juvenile HD patients. An N-terminal fragment of mutant huntingtin forms aggregates in neuronal nuclei in the brains of transgenic mice and HD patients. Aggregation of expanded polyglutamine is thought to be a common pathological mechanism in HD and other glutamine repeat diseases. It is not clear how the length of the repeats is correlated with formation of protein aggregates. By expressing a series of huntingtin constructs encoding various glutamine repeats (23-150 units) in cultured cells we observed N-terminal fragments of huntingtin (amino acids 1-67 and 1-212), but not full-length huntingtins, with glutamine repeats >/=66 units formed protein aggregates. Huntingtin aggregation was not induced when the repeat was </=49 units and was markedly promoted by very long repeats >/=120 units. This study suggests that various N-terminal fragments of mutant huntingtin can form aggregates and that aggregation is prompted by lengthening the glutamine repeat.

Interaction of huntingtin-associated protein with dynactin P150Glued

Huntingtin is the protein product of the gene for Huntington's disease (HD) and carries a polyglutamine repeat that is expanded in HD (>36 units). Huntingtin-associated protein (HAP1) is a neuronal protein and binds to huntingtin in association with the polyglutamine repeat. Like huntingtin, HAP1 has been found to be a cytoplasmic protein associated with membranous organelles, suggesting the existence of a protein complex including HAP1, huntingtin, and other proteins. Using the yeast two-hybrid system, we found that HAP1 also binds to dynactin P150(Glued) (P150), an accessory protein for cytoplasmic dynein that participates in microtubule-dependent retrograde transport of membranous organelles. An in vitro binding assay showed that both huntingtin and P150 selectively bound to a glutathione transferase (GST)-HAP1 fusion protein. An immunoprecipitation assay demonstrated that P150 and huntingtin coprecipitated with HAP1 from rat brain cytosol. Western blot analysis revealed that HAP1 was enriched in rat brain microtubules and comigrated with P150 and huntingtin in sucrose gradients. Immunofluorescence showed that transfected HAP1 colocalized with P150 and huntingtin in human embryonic kidney (HEK) 293 cells. We propose that HAP1, P150, and huntingtin are present in a protein complex that may participate in dynein-dynactin-associated intracellular transport.

Steroidal 5-en-3-ones, intermediates of the transformation of steroidal 5-en-3 beta-ols to steroidal 4-en-3,6-diones oxidized by pyridinium dichromate and pyridinium chlorochromate

Oxidation of cholesterol (1a) or pregnenolone (1b) with pyridinium dichromate (PDC) in dimethylformamide (DMF) or in dichloromethane (DCM) and pyridinium chlorochromate (PCC) in DCM provided cholest-4-en-3,6-dione (2a) or pregn-4-en-3,6,20-trione (2b). TLC monitoration of the reactions implied that cholest-5-en-3-one (3a) or pregn-5-en-3,20-dione (3b) and cholest-4-en-3-one (4a) or pregn-4-en-3,20-dione (4b) might be intermediates. Individual oxidation of 3a or 3b with PDC and PCC could give 2a or 2b, but 4a or 4b remained unchanged. Further investigation indicated that 4a or 4b was an isomerization product of 3a or 3b on silica gel TLC plate rather than really existence in the reaction mixture. These results shown steroidal 5-en-3-ones were intermediates of the transformation of steroidal 5-en-3 beta-ols to steroidal 4-en-3,6-diones oxidized by PDC and PCC.

[Suppressive effects of a plant-origin polyol, dulcitol on collagen-induced arthritis in mice]

Dulcitol was isolated chemically from Celastrus obiculatus Thumb and determined by HPLC. Effects of dulcitol were examined on collagen-induced arthritis (CIA) in DBA/1J mice. From 6 weeks after the first immunization with bovine type II collagen, dulcitol (100 mg/kg body weight/day) was administered orally to immunized mice for 9 weeks. Clinical score of CIA was improved significantly by dulcitol intervention compared with the non-treated CIA mice. Radiographic score of phalangeal destruction was also improved by dulcitol treatment. These findings suggest that dulcitol may play a role in regulation of some inflammatory responses in the present arthritis model. Significant reduction of percentage of CD4+ and CD8+ T cell subsets in the spleen leucocytes of CIA mice was observed by flow cytometry. Almost normal level of CD4+ and CD8+ T cells was observed in dulcitol-treated groups, suggesting T cell-modifying effect of dulcitol in CIA. Weight of spleen was larger in CIA mice and it was not affected by dulcitol. Anti-collagen antibody titer was increased in CIA mice, and it was not affected by dulcitol, either. Improvement of the changes of CD4+ and CD8+ T cells in the spleen by dulcitol may suggest its modulatory effect on cellular immunity.

cDNAs with long CAG trinucleotide repeats from human brain

Twelve diseases, most with neuropsychiatric features, arise from trinucleotide repeat expansion mutations. Expansion mutations may also cause a number of other disorders, including several additional forms of spinocerebellar ataxia, bipolar affective disorder, schizophrenia, and autism. To obtain candiate genes for these disorders, cDNA libraries from adult and fetal human brain were screened at high stringency for clones containing CAG repeats. Nineteen cDNAs were isolated and mapped to chromosomes 1, 2, 4, 6, 7, 8, 9, 12, 16, 19, 20, and X. The clones contain between 4 and 17 consecutive CAG, CTG, TCG, or GCA triplets. Clone H44 encodes 40 consecutive glutamines, more than any other entry in the nonredundant GenBank protein database and well within the range that causes neuronal degeneration in several of the glutamine expansion diseases. Eight cDNAs encode 15 or more consecutive glutamine residues, suggesting that the gene products may function as transcription factors, with a potential role in the regulation of neurodevelopment or neuroplasticity. In particular, the conceptual translation of clone CTG3a contains 18 consecutive glutamines and is 45% identical to the C-terminal 306 residues of the mouse numb gene product. These genes are therefore candidates for diseases featuring anticipation, neurodegeneration, or abnormalities of neurodevelopment.

Calcium phosphate formation induced on silica in bamboo

The effect of in vitro induction of calcium phosphate on bamboo surfaces is reported for the first time. Bamboo is studied for biomaterial application due to its elasticity modulus being closer to human bone than other biomaterials. Following an earlier study of cytotoxicity and precipitation of apatite on ground tissue and vascular bundles of bamboo, the composition and function of the minerals in bamboo, especially silica, are considered in the present work. It is found that in both outer and inner surfaces of bamboo culm, there exists some silica. Bamboo elicits an inert response when soaked directly in calcification solution. After the rind of bamboo is treated with sodium hydroxide solution, the silica underneath can induce precipitation of calcium phosphate in an ambient environment. Furthermore, by subsequent grafting with polyethylene glycol (PEG 1000), calcium phosphate induction of bamboo rind can be improved, depending on the concentration of NaOH solution and treatment time. Heat treatment of bamboo can remove the organic materials around the minerals in bamboo, allowing the calcification behaviour of the silica-containing inorganic phase of bamboo in aqueous solution to be studied.

Acipimox attenuates hypertriglyceridemia in dyslipidemic noninsulin dependent diabetes mellitus patients without perturbation of insulin sensitivity and glycemic control

Hyperlipidemia, hypertriglyceridemia in particular, is a common feature in patients with noninsulin dependent diabetes mellitus (NIDDM) and may associate with insulin insensitivity. Acipimox, being widely prescribed for treating hypertriglyceridemia, is also used in NIDDM patients for their dyslipidemia. In the present study, we evaluated the effect of acipimox in Chinese NIDDM patients with hypertriglyceridemia. A total of 16 patients enrolled in a double-blind, randomized, placebo-controlled and two-period crossover study. After an 8 week run-in period, patients were randomly assigned into two groups receiving either acipimox (250 mg, twice daily) or placebo treatment. A total of 12 weeks later, these two groups switched their treatment for an additional 12 weeks. Blood samples were collected at the end of the run-in period and then at 4-week intervals in the whole study for lipid profile. A modified insulin suppression test was performed at the ends of the run-in period, 12-week and 24-week treatment to assess changes in insulin sensitivity. Our results showed that acipimox significantly lowered serum total triglyceride while compared to those by placebo. However, no difference was observed in serum non-esterified fatty acid, low-density lipoprotein cholesterol, total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C) and HDL-C/ TC ratio between the two groups. Furthermore, glycemic indices and insulin sensitivity were similar during the base-line, placebo or acipimox periods. Taken together, our data suggest that acipimox significantly lowered TG without perturbation of insulin sensitivity in hypertriglyceridemic NIDDM patients.

In vitro calcium phosphate formation on a natural composite material, bamboo

A natural self-reinforced composite material, bamboo, is studied for the first time as a biomedical material. Its anatomical structure was investigated and its mechanical properties were measured and compared with those of some common bone-bonding or bone-repairing biomaterials. It is found that, among all kinds of biomaterials, bamboo has the closest modulus of elasticity to human long bone. The cytotoxicity of bamboo was tested using the agar overlay method before and after heat or chemical treatments. The results reveal that ethanol, methanol and toluene can remove toxic leachable components from bamboo to some extent through extraction. After grafting a polymer whose molecule includes poly(ethylene glycol), alpha,omega-di(aminopropyl)poly(ethylene glycol) 800 on bamboo, bamboo has the ability to form a calcium phosphate coating after being immersed in calcification solution (simulated body fluid and accelerated calcification solution). The characteristics and the morphology of the mineral formed on bamboo were studied by infrared spectroscopy and scanning electron microscopy.

Avoiding serious complications in laparoscopic cholecystectomy--lessons learned from an experience of 2428 cases

Over a three-and-a-half year period, we performed 2428 cases of laparoscopic cholecystectomy (LC) and encountered 11 cases of serious procedure-related complications, including bile duct injuries in 4 patients, postoperative bleeding requiring laparotomy and haemostasis in 3 patients, bile leakage from the cystic duct stump, jejunal injury related to puncture, intraoperative injury to the duodenum and subdiaphragmatic abscess in 1 patient each respectively. Six patients required re-hospitalisation including 2 patients with pancreatitis, 1 patient with Ascaris cholangitis, 1 patient with residual stone of the common bile duct (CBD) after laparoscopic CBD exploration, 1 patient with a stone in the CBD after LC, and 1 patient with bile leakage from the cystic duct stump and peritonitis. Of the 2428 patients treated, there was only 1 operative mortality. This patient developed frequent episodes of supraventricular tachycardia. She was found to have pnuemonia on the 21st postoperative day and she died. Apart from this, 1 other patient was found to have primary cancer of the liver 1 month after LC. Based on our experience, we think that LC is safe for patients with benign disease of the gallbladder.

Tissue transglutaminase in apoptosis of photoreceptor cells in rat retina

PURPOSE

The possible involvement of tissue transglutaminase (tTG) in apoptosis during photoreceptor degeneration was examined in retinal photic injury in rats and in retinal dystrophy of Royal College of Surgeons (RCS) rats.

METHODS

Retinal photic injury was induced in 48 male Lewis albino rats by exposure to green fluorescent light of 300 to 320 foot-candles. The retinal tTG was examined by enzyme assay, immunohistochemistry, and Western blot analysis after 9, 12, or 24 hours of exposure or at 6 or 24 hours of dark adaptation after 24 hours of light exposure. Retinas from RCS rats at various stages of degeneration also were examined with similar methods.

RESULTS

There was a progressive increase in retinal tTG activity after 300 to 320 ft-c of light exposure, reaching a peak after 24 hours of light exposure. In the RCS rats, tTG activity increased with age. Western blot analysis revealed an immunoreactive band at 80 kDa, which increased in accordance with the transglutaminase activity in both models. In normal rat retinas, tTG immunolabeling was present only in the outer segments. There was an increased number of immunolabeled photoreceptor nuclei from 12 hours of light exposure to 24 hours of light exposure. In the RCS rat, increasing numbers of immunopositive photoreceptor nuclei from 20 to 50 days of age were noted.

CONCLUSIONS

The data associated increased retinal tTG activity and enzyme levels with photoreceptor cells undergoing apoptosis. The tTG-dependent irreversible cross-linking of intracellular protein may play an important role in causing the structural changes in cells undergoing apoptosis in the retina.

Lymphocyte apoptosis: mediation by increased type 3 inositol 1,4,5-trisphosphate receptor

B and T lymphocytes undergoing apoptosis in response to anti-immunoglobulin M antibodies and dexamethasone, respectively, were found to have increased amounts of messenger RNA for the inositol 1,4,5-trisphosphate receptor (IP3R) and increased amounts of IP3R protein. Immunohistochemical analysis revealed that the augmented receptor population was localized to the plasma membrane. Type 3 IP3R (IP3R3) was selectively increased during apoptosis, with no enhancement of type 1 IP3R (IP3R1). Expression of IP3R3 antisense constructs in S49 T cells blocked dexamethasone-induced apoptosis, whereas IP3R3 sense, IP3R1 sense, or IP3R1 antisense control constructs did not block cell death. Thus, the increases in IP3R3 may be causally related to apoptosis.

Huntingtin-associated protein (HAP1): discrete neuronal localizations in the brain resemble those of neuronal nitric oxide synthase

Huntington disease stems from a mutation of the protein huntingtin and is characterized by selective loss of discrete neuronal populations in the brain. Despite a massive loss of neurons in the corpus striatum, NO-generating neurons are intact. We recently identified a brain-specific protein that associates with huntingtin and is designated huntingtin-associated protein (HAP1). We now describe selective neuronal localizations of HAP1. In situ hybridization studies reveal a resemblance of HAP1 and neuronal nitric oxide synthase (nNOS) mRNA localizations with dramatic enrichment of both in the pedunculopontine nuclei, the accessory olfactory bulb, and the supraoptic nucleus of the hypothalamus. Both nNOS and HAP1 are enriched in subcellular fractions containing synaptic vesicles. Immunocytochemical studies indicate colocalizations of HAP1 and nNOS in some neurons. The possible relationship of HAP1 and nNOS in the brain is reminiscent of the relationship of dystrophin and nNOS in skeletal muscle and suggests a role of NO in Huntington disease, analogous to its postulated role in Duchenne muscular dystrophy.

Abnormal IL-4 gene expression by atopic dermatitis T lymphocytes is reflected in altered nuclear protein interactions with IL-4 transcriptional regulatory element

Among the atopic disease, atopic dermatitis is characterized by the highest levels of serum IgE and by increased peripheral blood T-cell interleukin-4 (IL-4) production. IL-4 promotes IgE synthesis by B cells and stimulates the growth of IL-4-producing T cells and may contribute to the pathogenesis of this disease. In this study, in situ hybridization established that atopic dermatitis patients have a higher frequency of IL-4-producing peripheral blood T cell when compared to normal subjects. These in vivo-derived T cells were used to examine the signaling requirements of IL-4 production and the nuclear factors that associate with a critical IL-4 transcriptional regulatory element between -88 and -60 relative to the IL-4 transcription initiation site, the activation responsive element. We demonstrate that, as in T-cell lines, proteins belonging to the NF-AT and AP-1 family of transcription factors are present in stimulated cell extracts and specifically associate with the activation responsive element. Dysregulated IL-4 production is reflected in the nuclear proteins that associated this element. Using gel shift assays, we found that 12 of 12 nuclear extracts from stimulated atopic T cells formed the activation-dependent protein-DNA complex, compared to only 2 of 12 normal T-cell extracts. Activation complex formation correlated with the relative level of IL-4 mRNA and protein produced in stimulated T cells, suggesting that abnormal IL-4 gene expression in atopic disease may be linked to alterations in nuclear protein interactions with these promoter elements.

Analysis of thirteen trinucleotide repeat loci as candidate genes for schizophrenia and bipolar affective disorder

A group of diseases are due to abnormal expansions of trinucleotide repeats. These diseases all affect the nervous system. In addition, they manifest the phenomenon of anticipation, in which the disease tends to present at an earlier age or with greater severity in successive generations. Many additional genes with trinucleotide repeats are believed to be expressed in the human brain. As anticipation has been reported in schizophrenia and bipolar affective disorder, we have examined allele distributions of 13 trinucleotide repeat-containing genes, many novel and all expressed in the brain, in genomic DNA from schizophrenic (n = 20-97) and bipolar affective disorder patients (23-30) and controls (n = 43-146). No evidence was obtained to implicate expanded alleles in these 13 genes as causal factors in these diseases.

cDNA cloning and characterization of an atrophin-1 (DRPLA disease gene)-related protein

Dentatorubral and pallidoluylsian atrophy (DRPLA) is a progressive neurological disorder characterized by neuronal degeneration, especially in the cerebellar dentate nucleus. DRPLA is caused by an unstable expansion of a CAG trinucleotide repeat coding for glutamine in a gene of unknown function, termed atrophin-1, located on chromosome 12. To gain additional understanding of atrophin-1, we have isolated a second member of the atrophin-1 gene family by screening rat cDNA libraries. The 1006-amino-acid product of this gene, which we have termed rat atrophin related protein(rARP), does not contain a glutamine repeat, but it does contain two regions of alternating acidic and basic amino residues similar to those found in atrophin-1. rARP is widely expressed as both a 7.4- and a 9.4-kb message, with enrichment in cerebellum and testis. Like atrophin-1, the rARP in vitro translation product migrates more slowly on SDS-polyacrylamide gel electrophoresis than predicted by molecular weight. We conclude that, at least in the rat, polyglutamine is not an essential feature of the atrophin family of genes.