Octreotide and pasireotide effects on medullary thyroid carcinoma (MTC) cells growth, migration and invasion.

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine neoplasm of the parafollicular thyroid C cells. Although somatostatin receptors are expressed by MTCs, treatment with octreotide has shown poor efficacy, whereas recently pasireotide has demonstrated antiproliferative effects in persistent postoperative MTCs. Aim of this study was to test the effects of octreotide and pasireotide on MTC cells proliferation, cell cycle proteins expression, MAPK activation, apoptosis, calcitonin secretion, migration and invasion in TT cell line as well as in primary MTC cultured cells. Our results showed that both octreotide and pasireotide reduced TT cell proliferation (-35.2 ± 12.1%, p < 0.001, and -25.3 ± 24.8%, p < 0.05, at 10-8 M, respectively), with concomitant inhibition of ERK phosphorylation and cyclin D1 expression. This cytostatic effect was accompanied by a proapoptotic action, with an increase of caspase3/7 activity of 1.5-fold. Moreover, both octreotide and pasireotide inhibited cell migration (-50.9 ± 11.3%, p < 0.01, and -40.5 ± 17%, p < 0.05, respectively) and invasion (-61.3 ± 35.1%, p < 0.05, and -49.7 ± 18%, p < 0.01, respectively). No effect was observed on calcitonin secretion. We then tried to extend these observations to primary cultures (n = 5). Octreotide and/or pasireotide were effective in reducing cells proliferation in 3 out of 5 tumors, and to induce cell apoptosis in 1 out of 3 MTCs. Both octreotide and pasireotide were able to reduce cell migration in all MTC tested. SST2, SST3 and SST5 were expressed in all MTC, with a tendency to increased expression of SST2 in RET mutated vs wild type MTCs. In agreement, inhibition of mutated RET in TT cells reduced SST2 expression. In conclusion, we demonstrated that octreotide and pasireotide inhibited cell proliferation and invasiveness in a subset of MTC, supporting their potential use in the control of tumor growth.

Cofilin is a mediator of RET-promoted medullary thyroid carcinoma cell migration, invasion and proliferation.

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor that originates from parafollicular thyroid C cells and accounts for 5% of thyroid cancers. In inherited cases of MTC, and in about 40% of sporadic cases, activating mutations of the receptor tyrosine kinase proto-oncogene RET are found. Constitutively active RET triggers signaling pathways involved in cell proliferation, survival and motility, but the mechanisms underlying malignant transformation of C-cells have been only partially elucidated. Cofilin is a key regulator of actin cytoskeleton dynamics. A crucial role of cofilin in tumor development, progression, invasion and metastasis has been demonstrated in different human cancers, but no data are available in MTC. Interestingly, RET activation upregulates cofilin gene expression. The aim of this study was to investigate cofilin contribution in invasiveness and growth of MTC cells, and its relevance in the context of mutant RET signaling. We found that cofilin transfection in human MTC cell line TT significantly increased migration (178 ±â€¯44%, p < 0.001), invasion (165 ±â€¯28%, p < 0.01) and proliferation (146 ±â€¯18%, p < 0.001), accompanied by an increase of ERK1/2 phosphorylation (2.23-fold) and cyclin D1 levels (1.43-fold). Accordingly, all these responses were significantly reduced after genetic silencing of cofilin (-55 ±â€¯10% migration, p < 0.001, -41 ±â€¯8% invasion, p < 0.001, -17 ±â€¯3% proliferation, p < 0.001). These results have been confirmed in primary cells cultures obtained from human MTCs. The inhibition of constitutively active RET in TT cells by both the RET pharmacological inhibitor RPI-1 and the transfection of dominant negative RET mutant (RETΔTK) resulted in a reduction of cofilin expression (-37 ±â€¯8%, p < 0.001 and -31 ±â€¯16%, p < 0.01, respectively). Furthermore, RPI-1 inhibitory effects on TT cell migration (-57 ±â€¯13%, p < 0.01), but not on cell proliferation, were completely abolished in cells transfected with cofilin. In conclusion, these data indicate that an unbalanced cofilin expression, induced by oncogenic RET, contributes to promote MTC invasiveness and growth, suggesting the possibility of targeting cofilin pathway for more effective treatment of MTC.

Bone involvement and mineral metabolism in Williams' syndrome.

CONTEXT: The previous studies suggested a possible increased risk of hypercalcaemia and reduced bone mineral density (BMD) in Williams' syndrome (WS). However, an extensive study regarding bone metabolism has never been performed. OBJECTIVE: To investigate bone health in young adults with WS. DESIGN: Cross-sectional study. SETTINGS: Endocrinology and Metabolic Diseases and Medical Genetic Units. PATIENTS: 29 WS young adults and 29 age- and sex-matched controls. MAIN OUTCOME MEASURES: In all subjects, calcium, phosphorus, bone alkaline phosphatase (bALP), parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHVitD), osteocalcin (OC), carboxyterminal cross-linking telopeptide of type I collagen (CTX), 24-h urinary calcium and phosphorus, femoral-neck (FN) and lumbar-spine (LS) BMD and vertebral fractures (VFx) were assessed. In 19 patients, serum fibroblast growth factor-23 (FGF23) levels were measured. RESULTS: WS patients showed lower phosphorus (3.1 ± 0.7 vs 3.8 ± 0.5 mg/dL, p = 0.0001) and TmP/GFR (0.81 ± 0.32 vs 1.06 ± 0.25 mmol/L, p = 0.001), and an increased prevalence (p = 0.005) of hypophosphoremia (34.5 vs 3.4%) and reduced TmP/GFR (37.9 vs 3.4%). Moreover, bALP (26.3 ± 8.5 vs 35.0 ± 8.0 U/L), PTH (24.5 ± 12.6 vs 33.7 ± 10.8 pg/mL), OC (19.4 ± 5.3 vs 24.5 ± 8.7 ng/mL), and FN-BMD (- 0.51 ± 0.32 vs 0.36 ± 0.32) were significantly lower (p < 0.05), while CTX significantly higher (401.2 ± 169.3 vs 322.3 ± 122.4 pg/mL, p < 0.05). Serum and urinary calcium and 25OHVitD levels, LS-BMD and VFx prevalence were comparable. No cases of hypercalcemia and suppressed FGF23 were documented. Patients with low vs normal phosphorus and low vs normal TmP/GFR showed comparable FGF23 levels. FGF23 did not correlate with phosphorus and TmP/GFR values. CONCLUSIONS: Adult WS patients have reduced TmP/GFR, inappropriately normal FGF23 levels and an uncoupled bone turnover with low femoral BMD.

Terminalia catappa: Chemical composition, in vitro and in vivo effects on Haemonchus contortus.

Haemonchus contortus is the most important nematode in small ruminant systems, and has developed tolerance to all commercial anthelmintics in several countries. In vitro (egg hatch assay) and in vivo tests were performed with a multidrug strain of Haemonchus contortus using Terminalia catappa leaf, fruit pulp, and seed extracts (in vitro), or pulp and seed powder in lambs experimentally infected with H. contortus. Crude extracts from leaves, fruit pulp and seeds obtained with 70% acetone were lyophilized until used. In vitro, the extracts had LC50=2.48µg/mL (seeds), LC50=4.62µg/mL (pulp), and LC50=20µg/mL (leaves). In vitro, seed and pulp extracts had LC50 similar to Thiabendazole (LC50=1.31µg/mL). Condensed tannins were more concentrated in pulp extract (183.92g of leucocyanidin/kg dry matter) than in either leaf (4.6g) or seed (35.13g) extracts. Phytochemical tests established that all extracts contained alkaloids, flavonoids, saponins, phenols, and terpenoids. Based on these results, in vivo tests were performed to evaluate the anthelmintic activity of T. catappa whole fruit (pulp+seed) powder. Male Santa Ines lambs were artificially infected with multidrug-resistant H. contortus and divided, according to similar fecal egg count (FEC) and weight, into two groups: Control (infected/untreated) and treated (infected/treated with whole fruit powder). Whole fruit powder was mixed with concentrate and provided at 2g/kg of body weight (BW) for five days. After treatment, parasitological analysis (FEC and egg hatch assay), renal profile (urea and creatinine), liver profile (aspartate aminotransferase) and BW were determined. In vitro (based on LC50), seed/pulp extracts had ovicidal effect similar to Thiabendazole but whole fruit powder had no anthelmintic effect on adult nematodes in the abomasum. We discuss the plausible causes of the lack of in vivo activity.

Synergistic interaction of ten essential oils against Haemonchus contortus in vitro.

Anthelmintic resistance in sheep gastrointestinal nematodes is a worldwide problem. Multi-drug resistant haemonchosis is the most serious impediment for small ruminant systems, and there are no new drug candidates currently under development. Molecules from natural sources have demonstrated anthelmintic activity against parasites. In this work, the monoterpenoids carvacrol, carvone, cineole, linalool, limonene, and thymol and the phenylpropanoids cinnamaldehyde, anethole, vanillin, and eugenol were assessed individually or in mixtures of ten binary, three ternary, and three quaternary combinations using the in vitro egg hatch assay with eggs of a multi-drug resistant strain of Haemonchus contortus. The main objective of this study was to identify the most effective interaction among essential oils with the greatest individual anthelmintic efficacy and to determine the most powerful combinations. The essential oils were ranked by their 50% lethal concentration (LC50) as follows (mg/mL): cinamaldehyde (0.018), anethole (0.070), carvone (0.085), carvacrol (0.11), thymol (0.13), linalool (0.29), vanillin (0.57), eugenol (0.57), cineole (4.74), and limonene (207.5). Quantification of synergism, additive effect, and antagonism were calculated for binary, ternary, and quaternary combinations. The best anthelmintic effect resulting from synergistic activity among 16 different combinations was for cinnamaldehyde:carvacrol (CL50 0.012mg/mL) and anethole:carvone (CL50 0.013mg/mL). These results indicate that these binary combinations would be promising to be tested in sheep infected with H. contortus.

Role of UGT1A1 and ADH gene polymorphisms in pegvisomant-induced liver toxicity in acromegalic patients.

CONTEXT: Hepatotoxicity is one of the most serious adverse effects in acromegalic patients treated with pegvisomant (PEG-V). Recent studies have found an association between this adverse event and the UGT1A1 allele 28 polymorphism associated with Gilbert's syndrome. OBJECTIVE: To determine whether UGT1A1*28 and alcohol dehydrogenase (ADH) polymorphisms influence liver toxicity during PEG-V treatment. DESIGN AND SETTING: Multicenter observational retrospective study conducted in 13 tertiary care endocrinology units in Italy. PATIENTS: A total of 112 patients with active disease resistant to somatostatin analogs (SSTa) and 108 controls were enrolled. INTERVENTIONS: Clinical and biochemical data were recorded by electronic clinical reporting forms. Blood or DNA samples were sent to the coordinating center for genotyping. RESULTS: No differences in genotypes between patients and controls were found. During PEG-V therapy liver function tests (LFT), abnormalities and overt hepatotoxicity developed in 17 and 4.5% of patients respectively. Logistic and linear regression analyses showed an association between LFT abnormalities during the follow-up visit and prior events of LFT abnormalities in medical history (odds ratio=1.25; P=0.04) and the number of concomitant medications, other than SSTa (B=3.9; P=0.03). No correlation between LFT alterations and UGT1A1 allele 28 as well as ADH1C and B polymorphisms was found. CONCLUSIONS: UGT1A1 allele 28 and ADH1C and B polymorphisms do not predict increased risk of hepatotoxicity during PEG-V therapy. Conversely, patients with multi-therapies and with previous episodes of liver disease should be carefully managed, due to the observed association between these conditions and LFT abnormalities during PEG-V therapy.

Impact of IGF(CA)19 gene polymorphism on the metabolic response to GH therapy in adult GH-deficient patients.

OBJECTIVE: A polymorphism in the promoter region of the IGF1 gene has been linked to serum IGF1 levels, risk of diabetes, and cardiovascular diseases with conflicting results. The aim of this study was to investigate the impact of this polymorphism on the short-term (1 year, n=98) and long-term (5 years, n=50) metabolic response to recombinant human GH (rhGH) in GH-deficient (GHD) adults. DESIGN AND METHODS: Prospective study on GHD adults. Different genotypes were studied by microsatellite method. According to the most frequent 192 bp allele (19 cytosine-adenosine-repeats), subjects were divided into homozygous (19/19), heterozygous (19/X), and noncarriers (X/X). RESULTS: Basal characteristics of patients as well as their response to rhGH in terms of decrease in body fat percentage and increase in IGF1 levels were not different in the three genotype-groups. Conversely, after 1-year rhGH, a significant worsening of insulin sensitivity (i.e. increase in fasting glucose levels and homeostasis model assessment of insulin resistance) and a significant improvement in lipid profile (i.e. reduction in total cholesterol and LDL-cholesterol) were recorded only in homozygous subjects. In the long-term, insulin sensitivity was restored in all the patients, while a significant improvement in lipid profile was observed in homozygous and heterozygous subjects, but not in noncarrier subjects. No difference in rhGH dose among groups was recorded throughout the study. CONCLUSIONS: In GHD adults, the presence of the WT allele in the IGF1 gene promoter may enhance sensitivity to either negative or positive metabolic changes induced by rhGH.

Screening for GNAS genetic and epigenetic alterations in progressive osseous heteroplasia: first Italian series.

Progressive osseous heteroplasia (POH) is a rare autosomal dominant disorder of mesenchymal differentiation characterized by progressive heterotopic ossification (HO) of dermis, deep connective tissues and skeletal muscle. Usually, initial bone formation occurs during infancy as primary osteoma cutis (OC) then progressively extending into deep connective tissues and skeletal muscle over childhood. Most cases of POH are caused by paternally inherited inactivating mutations of GNAS gene. Maternally inherited mutations as well as epigenetic defects of the same gene lead to pseudohypoparathyroidism (PHP) and Albright's hereditary osteodystrophy (AHO). During the last decade, some reports documented the existence of patients with POH showing additional features characteristic of AHO such as short stature and brachydactyly, previously thought to occur only in other GNAS-associated disorders. Thus, POH can now be considered as part of a wide spectrum of ectopic bone formation disorders caused by inactivating GNAS mutations. Here, we report genetic and epigenetic analyses of GNAS locus in 10 patients affected with POH or primary OC, further expanding the spectrum of mutations associated with this rare disease and indicating that, unlike PHP, methylation alterations at the same locus are absent or uncommon in this disorder.

In vitro isolation from Amblyomma ovale (Acari: Ixodidae) and ecological aspects of the Atlantic rainforest Rickettsia, the causative agent of a novel spotted fever rickettsiosis in Brazil.

Recently, a novel human rickettsiosis, namely Atlantic rainforest spotted fever, was described in Brazil. We herein report results of a survey led around the index case in an Atlantic rainforest reserve in Peruibe municipality, southeastern Brazil. A Rickettsia parkeri-like agent (Rickettsia sp. Atlantic rainforest genotype) and Ricketsia bellii were isolated from adult Amblyomma ovale ticks collected from dogs. Molecular evidence of infection with strain Atlantic rainforest was obtained for 30 (12.9%) of 232 A. ovale adult ticks collected from dogs. As many as 88.6% of the 35 examined dogs had anti-Rickettsia antibodies, with endpoint titres at their highest to R. parkeri. High correlation among antibody titres in dogs, A. ovale infestations, and access to rainforest was observed. Amblyomma ovale subadults were found predominantly on a rodent species (Euryoryzomys russatus). From 17 E. russatus tested, 6 (35.3%) displayed anti-Rickettsia antibodies, with endpoint titres highest to R. parkeri. It is concluded that Atlantic rainforest genotype circulates in this Atlantic rainforest area at relatively high levels. Dogs get infected when bitten by A. ovale ticks in the forest, and carry infected ticks to households. The role of E. russatus as an amplifier host of Rickettsia to A. ovale ticks deserves investigation.

Experimental infection of the tick Amblyomma cajennense, Cayenne tick, with Rickettsia rickettsii, the agent of Rocky Mountain spotted fever.

In the laboratory, Amblyomma cajennense (Acari: Ixodidae) (Fabricius) larvae, nymphs and adults were exposed to Rickettsia rickettsii by feeding on needle-inoculated animals, and thereafter reared on uninfected guinea pigs or rabbits. Regardless of the tick stage that acquired the infection, subsequent tick stages were shown to be infected (confirming transstadial and transovarial transmissions) and were able to transmit R. rickettsii to uninfected animals, as demonstrated by serological and molecular analyses. However, the larval, nymphal and adult stages of A. cajennense were shown to be partially refractory to R. rickettsii infection, as in all cases, only part of the ticks became infected by this agent, after being exposed to rickettsemic animals. In addition, less than 50% of the infected engorged females transmitted rickettsiae transovarially, and when they did so, only part of the offspring became infected, indicating that vertical transmission alone is not enough to maintain R. rickettsii in A. cajennense for multiple generations. Finally, the R. rickettsii-infected tick groups had lower reproductive performance than the uninfected control group. Our results indicate that A. cajennense have a low efficiency to maintain R. rickettsii for successive generations, as R. rickettsii-infection rates should decline drastically throughout the successive tick generations.

Peripheral insulin-like factor 3 concentrations are reduced in men with type 2 diabetes mellitus: effect of glycemic control and visceral adiposity on Leydig cell function.

BACKGROUND AND AIM: Hypogonadism frequently occurs in men with type 2 diabetes mellitus (T2DM), while the role of glycemic control and visceral obesity is still unclear. This study aimed to assess the Leydig cell function, including the new sensitive marker insulin-like factor 3 (INSL3), in T2DM patients without overt hypogonadism and the influence of either glycemic control or visceral adiposity. SUBJECTS AND METHODS: Thirty T2DM patients (age 57.1+/-6.2 years, body mass index (BMI) 28.0+/-4.3) without overt hypogonadism and 30 age- and BMI-matched controls were studied. Anthropometric, glycometabolic parameters and testosterone, SHBG, LH, INSL3 levels, bioavailable and free testosterone (BT and cFT) were evaluated. The human chorionic gonadotrophin (hCG) test was also performed. RESULTS: Patients had lower total testosterone (452.6+/-130.0 vs 512.6+/-117.3 ng/dl, P=0.06), BT (189.7+/-36.4 vs 237.1+/-94.1 ng/dl, P=0.002), cFT (8.1+/-1.6 vs 10.1+/-4.0 ng/dl, P=0.002), and higher LH levels (3.5+/-1.6 vs 2.6+/-1.2 mU/ml, P=0.01) versus controls. Serum INSL3 concentrations were also lower in patients (1.1+/-0.3 vs 1.5+/-0.7 ng/ml, P=0.01). These hormonal parameters, including INSL3, did not differ between T2DM patients with poor or good glycemic control (HbA1c>9 or <7% respectively). In patients, waist circumferences (97.9+/-12.4 cm) negatively correlated with INSL3 (P=0.03) and basal, as well as hCG-stimulated testosterone levels (P=0.04 and 0.004 respectively). Basal or stimulated hormonal levels and INSL3 concentrations were not different between patients with (40%) or without erectile dysfunction. CONCLUSIONS: An early impairment of the overall Leydig cell function is present in men with T2DM, mainly related to visceral adiposity rather than to glycemic control.

Dopamine D2 receptor gene polymorphisms and response to cabergoline therapy in patients with prolactin-secreting pituitary adenomas.

Dopamine-agonist cabergoline (CB) reduces prolactin (PRL) secretion and tumor size in 80% of patients with prolactin-secreting adenomas (PRL-omas) by binding type 2 dopamine receptor (DRD2). The mechanisms responsible for resistance to CB remain largely unknown. To assess the association of DRD2 with sensitivity to CB, TaqI-A1/A2, TaqI-B1/B2, HphI-G/T and NcoI-C/T genotypes were determined in a cross-sectional retrospective study, including 203 patients with PRL-oma. DRD2 alleles frequencies did not differ between patients and 212 healthy subjects. Conversely, NcoI-T allele frequency was higher in resistant rather than responsive patients, considering both PRL normalization (56.6 vs 45.3%, P=0.038) and tumor shrinkage (70.4 vs 41.4%, P=0.006). Finally, [TaqI A1-/TaqI B1-/HphI T-/NcoI T-] haplotype was found in 34.5% of patients normalizing PRL with < or =3 mg/week of CB vs 11.3% of resistants (P=0.021). In conclusion, resistance to CB was associated with DRD2 NcoI-T+ allele, consistent with evidence suggesting that this variant may lead to reduction and instability of DRD2 mRNA or protein.

ADP-ribosylation of Rab5 by ExoS of Pseudomonas aeruginosa affects endocytosis.

Pseudomonas aeruginosa exoenzyme S (ExoS) is an ADP-ribosyltransferase that modifies low-molecular-weight GTPases. Here we studied the effect of Rab5 ADP-ribosylation by ExoS on its cellular function, i.e., regulation of early endocytic events. Coculture of CHO cells with P. aeruginosa induced a marked decrease in horseradish peroxidase (HRP) uptake compared to noninfected cells, while coculture with a P. aeruginosa mutant strain that fails to produce ExoS did not lead to any change in HRP uptake. Microinjection of recombinant ExoS into Xenopus oocytes induced strong inhibition of basal HRP uptake by oocytes. Moreover, coinjection of recombinant ExoS with Rab5 abolished the typical stimulation of HRP uptake obtained after GTPase microinjection. Cytosols prepared from injected oocytes were used in an endosome-endosome fusion assay. Cytosol from ExoS-microinjected oocytes was ineffective in promoting endosome-endosome fusion. However, in these conditions, the addition of Rab5 to the assay led to fusion recovery. Finally, we found that the interaction of Rab5 with EEA1 was markedly diminished after Rab5 ADP-ribosylation by ExoS.

A homeobox gene, vax2, controls the patterning of the eye dorsoventral axis.

We have identified a transcription factor specifically expressed in the developing vertebrate eye. We named this gene vax2 because of the high degree of sequence similarity to the recently described vax1. Both in the human and mouse genomes, vax2 is localized in the vicinity of the emx1 gene. This mapping assignment, together with the previously reported colocalization of Vax1 and Emx2 in mouse, indicates that the vax and the emx genes may be organized in clusters. vax2 has a remarkable expression domain confined to the ventral portion of the prospective neural retina in mouse, human, and Xenopus. The overexpression of either the frog Xvax2 or the human VAX2 in Xenopus embryos leads to an aberrant eye phenotype and, in particular, determines a ventralizing effect on the developing eye. The expression domain of the transcription factor Xpax2, normally confined to the ventral developing retina, extends to the dorsal region of the retina after overexpression of vax2. On the other hand, the expression of Xvent2, a molecular marker of the dorsal retina, is strongly reduced. Furthermore, vax2 overexpression induces a striking expansion of the optic stalk, a structure deriving from the ventralmost region of the eye vesicle. Altogether, these data indicate that vax2 plays a crucial role in eye development and, in particular, in the specification of the ventral optic vesicle.

Rapid detection of 21-hydroxylase deficiency mutations by allele-specific in vitro amplification and capillary zone electrophoresis.

A quick diagnosis of the classic form of 21-hydroxylase deficiency (simple virilizing and salt wasting) is of great importance, especially for prenatal diagnosis and treatment in pregnancies at risk. A method for simultaneous detection of common point mutations in the P450c21 B gene is here proposed by combining a nested PCR amplification refractory mutation system (ARMS) with capillary zone electrophoresis (CZE) in sieving liquid polymers. In the first PCR, B genes are selectively amplified. In the nested reaction, ARMS-detected wild-type and mutated alleles are separately pooled and resolved by CZE. CZE is performed in coated capillaries in the presence of 30 g/L hydroxyethyl cellulose in the background electrolyte for size separation of the DNA analytes. For high-sensitivity detection the electrophoresis buffer contains the fluorescent dye SYBR Green I. Laser-induced fluorescence detection is obtained by excitation at 488 nm and signal collection at 520 nm. Specificity and reproducibility of the protocols were established by using samples from 75 Italian families with 21-hydroxylase deficiency already genotyped by allele-specific oligonucleotide hybridization or direct sequencing. Whereas dot-blot is time consuming because of the high number of hybridizations with radioactive probes, this present protocol is more rapid, giving sufficient separation on CZE after PCR reactions without preconcentration or desalting of samples.

Sequential actions of Rab5 and Rab7 regulate endocytosis in the Xenopus oocyte.

To explore the role of GTPases in endocytosis, we developed an assay using Xenopus oocytes injected with recombinant proteins to follow the uptake of the fluid phase marker HRP. HRP uptake was inhibited in cells injected with GTPgammaS or incubated with aluminum fluoride, suggesting a general role for GTPases in endocytosis. Injection of Rab5 into oocytes, as well as Rab5:Q79L, a mutant with decreased GTPase activity, increased HRP uptake. Injection of Rab5:S34N, the dominant-negative mutant, inhibited HRP uptake. Injection of N-ethylmaleimide-sensitive factor (NSF) stimulated HRP uptake, and ATPase-defective NSF mutants inhibited HRP uptake when coinjected with Rab5:Q79L, confirming a requirement for NSF in endocytosis. Surprisingly, injection of Rab7:WT stimulated both uptake and degradation/activation of HRP. The latter appears to be due to enhanced transport to a late endosomal/prelysosomal degradative compartment that is monensin sensitive. Enhancement of uptake by Rab7 appears to function via an Rab5-sensitive pathway in oocytes since the stimulatory effect of Rab7 was blocked by coinjection of Rab5:S34N. Stimulation of uptake by Rab5 was blocked by Rab5:S34N but not by Rab7:T22N. Our results suggest that Rab7, while functioning downstream of Rab5, may be rate limiting for endocytosis in oocytes.

Purification and characterization of beta-galactosidase from rat epididymal fluid.

Beta-galactosidase from rat epididymal fluid was purified by a combination of chromatographic techniques and precipitation with ammonium sulphate. Specific activity of the enzyme in the final precipitate was 18 times greater than in the original fluid, and it was practically free of N-acetyl-beta-D-glucosaminidase. A single major band was seen when the precipitate was analysed by sodium dodecylsulphate polyacrylamide gelectrophoresis (SDS-PAGE). The activity of the purified enzyme has an optimum at pH 4.5, and the temperature optimum is around 45 degrees C. The activity was inhibited by p-chloromercuribenzoic acid and ions such as Cd(II), Co(II), Cu(II) and Ag(I). Lactose does not appear to be a substrate for this enzyme.

Phagocytosed live Listeria monocytogenes influences Rab5-regulated in vitro phagosome-endosome fusion.

Survival or destruction of a pathogen following phagocytosis depends, in part, on fusion events between the phagosome and the endosomal or lysosomal compartments. Here we use an in vitro assay to show that phagosome-endosome fusion is regulated by the small GTPase rab5 and that fusion events are influenced by an internalized live organism, Listeria monocytogenes (LM). We compare the in vitro fusion of phagosomes containing heat-killed organisms (dead LM) with that of phagosomes containing a live nonhemolytic mutant (live LMhly-). Unlike the wild-type organism, LMhly- remains trapped inside the phagosome. Phagosome-endosome fusion was reconstituted using biotinylated organisms and endosomes containing horseradish peroxidase conjugated with avidin. With both live LMhly- and dead LM preparations, in vitro phagosome-endosome fusion was time-, temperature-, and cytosol-dependent. Live LMhly- phagosomes exhibited a faster rate of fusion. Fusion in both preparations was regulated by rab5 and possibly by other GTPases. Anti-rab5 antibodies and immunodepletion of cytosolic rab5 inhibited fusion. Addition of glutatione S-transferase-rab5 in the GTP form stimulated phagosome-endosome fusion, whereas addition of a dominant negative mutant of rab5 blocked fusion. Purified live LMhly- phagosomal membranes were enriched in rab5 as revealed by Western blotting, compared with dead LM phagosomes. Fusion of endosomes with dead LM containing phagosomes required ATP and was inhibited by ATP depletion and by N-ethylmaleimide (NEM) and anti-NEM-sensitive factor (NSF) antibodies. Unexpectedly, phagosome-endosome fusion with live LMhly--containing phagosomes was not inhibited by ATP depletion nor by NEM or anti-NSF antibodies. Western blot analysis revealed that live LMhly--containing phagosomes were enriched for membrane-bound NSF, while dead LM containing phagosomes contained low or undetectable quantities. Washing live LMhly--containing phagosomes with 0.5 M KCl removed NSF associated with the membranes and rendered them NEM, ATP, anti-NSF antibody sensitive for fusion. We conclude that rab5 regulates phagosome-endosome fusion and that live microorganisms can up-regulate this process by recruiting rab5 to the membrane.

Seven novel additional small mutations and a new alternative splicing in the human dystrophin gene detected by heteroduplex analysis and restricted RT-PCR heteroduplex analysis of illegitimate transcripts.

Around 35% of Duchenne and Becker muscular dystrophy (DMD/BMD) patients cannot be identified by techniques which identify major DMD rearrangements in the dystrophin gene. In order to characterize the gene defect in these patients, we screened 40 exons of the dystrophin gene by heteroduplex analysis on genomic DNA in 50 affected Italian males. Using conventional heteroduplex analysis and a modified heteroduplex analysis on restricted RT-PCR products of illegitimate transcripts, restricted RT-PCR heteroduplex analysis, we were able to identify 7 novel small mutations and a new alternative splicing involving exon 25 of the dystrophin gene in peripheral blood lymphocytes and skeletal muscle transcripts.