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1.
J Endocrinol Invest ; 2024 May 21.
Article in English | MEDLINE | ID: mdl-38773059

ABSTRACT

PURPOSE: The role of osteocalcin (OCN) in pubertal development, male hypogonadism, and the effect of testosterone (Te) replacement therapy (TRT) remains unclear. We aimed to investigate the total OCN (tOCN) concentrations in male patients with Klinefelter syndrome (KS), a model of adult hypergonadotropic hypogonadism. METHODS: This retrospective longitudinal study investigated 254 male patients with KS (47,XXY) between 2007 and 2021 at an academic referral center, categorized as (1) prepubertal, (2) pubertal, and (3) adults. All prepubertal patients were Te-naïve. Adult patients were subcategorized as (1) eugonadal, (2) hypogonadal, and (3) receiving TRT. We also analyzed 18 adult patients with available tOCN levels before and 3 months after TRT commencement. RESULTS: The tOCN levels varied throughout the lifespan according to pubertal status, were highest in eugonadal and significantly lower in TRT subjects, correlated with both LH (p = 0.017) and FSH levels (p = 0.004) in adults, and significantly declined after 3 months of TRT (p = 0.006) in the adult KS cohort. HPG-axis hormones levels demonstrated no correlation in prepubertal boys. Adjustment for age and body mass index confirmed previous results and revealed significant inverse correlations with total Te (p = 0.004), calculated free Te (p = 0.016), the Te/LH (p = 0.010), and calculated free Te/LH ratios (p = 0.031). CONCLUSION: In KS, a model of male hypergonadotropic hypogonadism, tOCN levels were not associated with gonadal function during normal prepuberty and pubertal development but were associated with worse testicular function and a higher degree of HPG stimulation in adults. TRT acutely reduced tOCN levels in adults.

2.
Nat Commun ; 15(1): 4313, 2024 May 21.
Article in English | MEDLINE | ID: mdl-38773109

ABSTRACT

Our brain is constantly extracting, predicting, and recognising key spatiotemporal features of the physical world in order to survive. While neural processing of visuospatial patterns has been extensively studied, the hierarchical brain mechanisms underlying conscious recognition of auditory sequences and the associated prediction errors remain elusive. Using magnetoencephalography (MEG), we describe the brain functioning of 83 participants during recognition of previously memorised musical sequences and systematic variations. The results show feedforward connections originating from auditory cortices, and extending to the hippocampus, anterior cingulate gyrus, and medial cingulate gyrus. Simultaneously, we observe backward connections operating in the opposite direction. Throughout the sequences, the hippocampus and cingulate gyrus maintain the same hierarchical level, except for the final tone, where the cingulate gyrus assumes the top position within the hierarchy. The evoked responses of memorised sequences and variations engage the same hierarchical brain network but systematically differ in terms of temporal dynamics, strength, and polarity. Furthermore, induced-response analysis shows that alpha and beta power is stronger for the variations, while gamma power is enhanced for the memorised sequences. This study expands on the predictive coding theory by providing quantitative evidence of hierarchical brain mechanisms during conscious memory and predictive processing of auditory sequences.


Subject(s)
Auditory Cortex , Auditory Perception , Magnetoencephalography , Humans , Male , Female , Adult , Auditory Perception/physiology , Young Adult , Auditory Cortex/physiology , Brain/physiology , Acoustic Stimulation , Brain Mapping , Music , Gyrus Cinguli/physiology , Memory/physiology , Hippocampus/physiology , Recognition, Psychology/physiology
3.
Trop Biomed ; 39(2): 203-208, 2022 Jun 01.
Article in English | MEDLINE | ID: mdl-35838091

ABSTRACT

The community that progressively colonizes a decaying corpse can be considered a small ecosystem mostly composed of sarcosaprophagous arthropods belonging to the orders Diptera and Coleoptera. Studies on these species are often performed through animal models to obtain data on their succession, behaviour and life cycle, together with information on habitat, corpse conditions, season and association with other species. These data may be relevant for forensic investigations, especially concerning the estimation of Post Mortem Interval (PMI). An investigation on the sarcosaprophagous insect community in a rural area was set in Calabria (Southern Italy), using a pig, Sus scrofa Linnaeus, 1758 (Artiodactyla: Suidae) as experimental model. Analyses of the community of Diptera and Coleoptera revealed the massive presence of Necrodes littoralis (Linnaeus, 1758) (Coleoptera: Silphidae). Adults of this species reached the carcass during the bloated stage and a large amount of larvae was detected from the decay stage onwards, simultaneous to the sharp decrease in dipteran larvae and pupae. The occurrence and the activity of N. littoralis should be considered to avoid misinterpretation and errors in estimating PMI in forensic investigation.


Subject(s)
Coleoptera , Diptera , Animals , Cadaver , Ecosystem , Feeding Behavior , Italy , Larva , Postmortem Changes
4.
Ann Ig ; 34(4): 415-420, 2022.
Article in English | MEDLINE | ID: mdl-34882165

ABSTRACT

Background: Invasive Meningococcal Disease is a severe disease mainly affecting infants and young children. Most infections are caused by serogroups A, B, C, W, X, and Y. In the last 10 years, serogroup B has been the main cause of Invasive Meningococcal Disease in Europe. Recent data resulting from an observational study conducted in Italy show a significant reduction in the number of Invasive Meningococcal Disease cases due to Neisseria meningitidis B after the introduction of vaccine 4CMenB. Thus, the Naples Team of Federation of Italian Primary Care Pediatricians and the Public Health Department started an active collaboration focused on vaccination process management (named "Progetto Via") with the aim of increasing Meningococcal B vaccination coverage. Study design: Source of data is the regional platform "GE.VA.". Every Primary care Pediatrician uses daily to record vaccination activity. This platform is integrated with data entered by operators of the District/Vaccination Center. Methods: Time: January 2019 - December 2019. The Federation of Italian Primary Care Pediatricians/Naples organized a meeting to identify six coordinators. The pediatricians could choose to counsel in their own offices and send children to the vaccination center or to counsel and vaccinate directly in their own clinics. Results: A total of 78 pediatricians took part in the project: 46 did only counseling and 32 did both counseling and vaccination in their medical clinic. Data obtained show an overall average vaccination coverage growth of about 13% in the first 4 months of the survey, and a further growth of about 11% in the following seven months, with a total growth in the entire period of 24%. The pediatricians' counseling is essential to recover non-compliant subjects, considering both the relationship of trust with the families and the visits already scheduled as an ideal moment for vaccinations' status check. Conclusions: The project highlights how an effective collaboration between family pediatricians and the Local Health Authority becomes valuable in getting closer to reach the Ministerial goal of 95%. Vaccination coverage increased significantly when family pediatricians supported the activity of vaccine centers in distress in many regional situations. The trust relationship, the hourly availability and the capillary network of family pediatricians' clinics were key elements for the success of this project and were also recognized by parents.


Subject(s)
Meningococcal Infections , Meningococcal Vaccines , Child , Child, Preschool , Humans , Infant , Italy , Meningococcal Infections/prevention & control , Pediatricians , Public Health , Vaccination , Vaccination Coverage
5.
Tropical Biomedicine ; : 203-208, 2022.
Article in English | WPRIM (Western Pacific) | ID: wpr-936919

ABSTRACT

@#The community that progressively colonizes a decaying corpse can be considered a small ecosystem mostly composed of sarcosaprophagous arthropods belonging to the orders Diptera and Coleoptera. Studies on these species are often performed through animal models to obtain data on their succession, behaviour and life cycle, together with information on habitat, corpse conditions, season and association with other species. These data may be relevant for forensic investigations, especially concerning the estimation of Post Mortem Interval (PMI). An investigation on the sarcosaprophagous insect community in a rural area was set in Calabria (Southern Italy), using a pig, Sus scrofa Linnaeus, 1758 (Artiodactyla: Suidae) as experimental model. Analyses of the community of Diptera and Coleoptera revealed the massive presence of Necrodes littoralis (Linnaeus, 1758) (Coleoptera: Silphidae). Adults of this species reached the carcass during the bloated stage and a large amount of larvae was detected from the decay stage onwards, simultaneous to the sharp decrease in dipteran larvae and pupae. The occurrence and the activity of N. littoralis should be considered to avoid misinterpretation and errors in estimating PMI in forensic investigation.

6.
Neuroimage ; 245: 118735, 2021 12 15.
Article in English | MEDLINE | ID: mdl-34813972

ABSTRACT

Information encoding has received a wide neuroscientific attention, but the underlying rapid spatiotemporal brain dynamics remain largely unknown. Here, we investigated the rapid brain mechanisms for encoding of sounds forming a complex temporal sequence. Specifically, we used magnetoencephalography (MEG) to record the brain activity of 68 participants while they listened to a highly structured musical prelude. Functional connectivity analyses performed using phase synchronisation and graph theoretical measures showed a large network of brain areas recruited during encoding of sounds, comprising primary and secondary auditory cortices, frontal operculum, insula, hippocampus and basal ganglia. Moreover, our results highlighted the rapid transition of brain activity from primary auditory cortex to higher order association areas including insula and superior temporal pole within a whole-brain network, occurring during the first 220 ms of the encoding process. Further, we discovered that individual differences along cognitive abilities and musicianship modulated the degree centrality of the brain areas implicated in the encoding process. Indeed, participants with higher musical expertise presented a stronger centrality of superior temporal gyrus and insula, while individuals with high working memory abilities showed a stronger centrality of frontal operculum. In conclusion, our study revealed the rapid unfolding of brain network dynamics responsible for the encoding of sounds and their relationship with individual differences, showing a complex picture which extends beyond the well-known involvement of auditory areas. Indeed, our results expanded our understanding of the general mechanisms underlying auditory pattern encoding in the human brain.


Subject(s)
Auditory Perception/physiology , Brain Mapping/methods , Magnetoencephalography , Memory, Short-Term/physiology , Music , Adolescent , Adult , Female , Humans , Male
7.
Endocrine ; 61(2): 327-335, 2018 08.
Article in English | MEDLINE | ID: mdl-29696556

ABSTRACT

PURPOSE: To assess different aspects of bone damage in untreated adult patients with Klinefelter Syndrome (KS) before and during testosterone replacement therapy (TRT). METHODS: Fifteen untreated hypogonadal men with KS and 26 control subjects (C) matched for age and BMI were recruited. Sex hormone levels were measured in all subjects. Lumbar spine (LS) and femoral (neck: FN and total hip: TH) bone mineral density (BMD), trabecular bone score (TBS), hip structure analysis (HSA) and fat measures (percentage of fat mass, android/gynoid ratio and visceral adipose tissue) were evaluated by DEXA. In KS patients, blood analysis and DEXA measurements were assessed at baseline and repeated yearly for three years during TRT. RESULTS: Fat measures were significantly higher in KS than C (p < 0.01). In contrast, mean LS, FN and TH BMD were significantly reduced in KS compared to C (p < 0.01), while there was no difference in TBS. HSA revealed a significantly lower cortical thickness and significantly higher buckling ratio in KS compared to C at all femoral sites (p < 0.01). In KS patients, TRT significantly increased BMD at LS only, but did not improve TBS and HSA parameters. Fat measures were inversely associated with TBS values, and TRT did not influence this relationship. CONCLUSIONS: In untreated hypogonadal men with KS, lumbar and femoral BMD was reduced, and femoral bone quality was impaired. Adiposity seemed to have a detrimental effect on lumbar bone microarchitecture, as indirectly evaluated by TBS. However, TRT failed to remedy these negative effects on bone.


Subject(s)
Bone and Bones/drug effects , Hormone Replacement Therapy , Hypogonadism/drug therapy , Klinefelter Syndrome/drug therapy , Testosterone/therapeutic use , Adult , Bone Density/drug effects , Bone and Bones/metabolism , Bone and Bones/pathology , Cancellous Bone/drug effects , Cancellous Bone/pathology , Case-Control Studies , Femur/drug effects , Femur/pathology , Femur Neck/drug effects , Femur Neck/pathology , Follow-Up Studies , Humans , Hypogonadism/complications , Hypogonadism/pathology , Klinefelter Syndrome/metabolism , Klinefelter Syndrome/pathology , Lumbar Vertebrae/drug effects , Lumbar Vertebrae/pathology , Male , Middle Aged , Time Factors
8.
Cell Mol Life Sci ; 61(23): 2954-64, 2004 Dec.
Article in English | MEDLINE | ID: mdl-15583857

ABSTRACT

RET is the receptor for glial-derived neurotrophic factor growth factors. It is a paradigm of a single gene that causes different types of human cancer when targeted by different genetic alterations. Like other receptor tyrosine kinases, once activated, RET recruits a variety of signaling molecules that mediate biological responses. Here we review data on the signaling pathways that lead to RET-mediated cell transformation and recent evidence that manipulation of RET holds promise for thyroid cancer treatment.


Subject(s)
Neoplasms/metabolism , Proto-Oncogene Proteins/physiology , Receptor Protein-Tyrosine Kinases/physiology , Carcinoma, Papillary/metabolism , Cell Transformation, Neoplastic , Humans , Ligands , Models, Biological , Models, Genetic , Phosphorylation , Protein Structure, Tertiary , Proto-Oncogene Proteins c-ret , Signal Transduction , Thyroid Neoplasms/metabolism
9.
J Chemother ; 16 Suppl 4: 49-51, 2004 Nov.
Article in English | MEDLINE | ID: mdl-15693160

ABSTRACT

The RET gene is frequently mutated in papillary thyroid carcinoma and in medullary thyroid carcinoma. We have identified three different anti-RET drugs: two pyrazolo-pyrimidines, PP1 and PP2 and an anilinoquinazoline, ZD6474 (AstraZeneca). These compounds are able to inhibit RET kinase activity in vitro (IC50 dose 100 nM) and in vivo and they can prevent RET mediated transformation. Finally, mutation of RET V804 to methionine or leucine, found in MTC patients, induces resistance to the three drugs.


Subject(s)
Piperidines/therapeutic use , Proto-Oncogene Proteins/genetics , Quinazolines/therapeutic use , Receptor Protein-Tyrosine Kinases/antagonists & inhibitors , Receptor Protein-Tyrosine Kinases/genetics , Thyroid Neoplasms/drug therapy , Thyroid Neoplasms/genetics , Carcinoma, Medullary/drug therapy , Carcinoma, Medullary/genetics , Carcinoma, Papillary/drug therapy , Carcinoma, Papillary/genetics , Dose-Response Relationship, Drug , Drug Administration Schedule , Female , Humans , Male , Mutation , Piperidines/pharmacology , Proto-Oncogene Proteins/drug effects , Proto-Oncogene Proteins c-ret , Quinazolines/pharmacology , Receptor Protein-Tyrosine Kinases/drug effects , Sensitivity and Specificity , Thyroid Neoplasms/pathology , Treatment Outcome
11.
Oncogene ; 20(2): 209-18, 2001 Jan 11.
Article in English | MEDLINE | ID: mdl-11313948

ABSTRACT

Tyrosine 1062 of Ret, which represents an intracytoplasmic docking site for multiple signaling molecules, is essential for Ret-mediated activation of phosphatidylinositol 3-Kinase (PI3-K). PI3-K, in turn, has been implicated in inducing cell survival and neoplastic transformation mediated by Ret. We have examined the mechanisms by which Ret stimulates PI3-K. Here we show that the Insulin Receptor Substrate-1 (IRS-1) is tyrosine phosphorylated and associated with the p85 regulatory subunit of PI3-K in response to Ret activation. IRS-1 coimmunoprecipitates with Ret and co-expression of IRS-1 results in the potentiation of Ret-mediated activation of Akt(PKB), a bona fide effector of PI3-K. The association with the PTB domain of IRS-1 depends on the phosphorylation of tyrosine 1062 of Ret. The deletion of asparagine 1059 (delN1059) and the substitution of leucine 1061 (L1061P), two Ret mutations identified in families affected by congenital megacolon (Hirschsprung's disease), impair the binding of IRS-1 to Ret as well as Ret-mediated Akt(PKB) stimulation. Finally, we show that Shc, which was previously identified as another ligand of Y1062 of Ret, competes with IRS-1 for the binding to Ret pY1062. All together, these findings suggest that IRS-1 is a component of the signaling pathway which leads to Ret-mediated PI3-K activation, a pathway which can be targeted by Hirschsprung-associated Ret mutations. The alternative binding of Shc and IRS-1 to Ret pY1062 can be a system to modulate the activation of different intracellular signaling pathways and to elicit different biological responses following Ret activation.


Subject(s)
Drosophila Proteins , Phosphatidylinositol 3-Kinases/metabolism , Phosphoproteins/metabolism , Protein Serine-Threonine Kinases , Proto-Oncogene Proteins/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , 3T3 Cells , Amino Acid Motifs , Amino Acid Substitution , Animals , Binding Sites , Binding, Competitive , Insulin Receptor Substrate Proteins , Mice , Mutation , Phosphoproteins/genetics , Phosphorylation , Polypyrimidine Tract-Binding Protein , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-akt , Proto-Oncogene Proteins c-ret , RNA-Binding Proteins/metabolism , Receptor Protein-Tyrosine Kinases/genetics , Ribonucleoproteins/metabolism
12.
Am J Hum Genet ; 67(6): 1544-54, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11078480

ABSTRACT

The design and feasibility of whole-genome-association studies are critically dependent on the extent of linkage disequilibrium (LD) between markers. Although there has been extensive theoretical discussion of this, few empirical data exist. The authors have determined the extent of LD among 38 biallelic markers with minor allele frequencies >.1, since these are most comparable to the common disease-susceptibility polymorphisms that association studies aim to detect. The markers come from three chromosomal regions-1,335 kb on chromosome 13q12-13, 380 kb on chromosome 19q13.2, and 120 kb on chromosome 22q13.3-which have been extensively mapped. These markers were examined in approximately 1,600 individuals from four populations, all of European origin but with different demographic histories; Afrikaners, Ashkenazim, Finns, and East Anglian British. There are few differences, either in allele frequencies or in LD, among the populations studied. A similar inverse relationship was found between LD and distance in each genomic region and in each population. Mean D' is.68 for marker pairs <5 kb apart and is.24 for pairs separated by 10-20 kb, and the level of LD is not different from that seen in unlinked marker pairs separated by >500 kb. However, only 50% of marker pairs at distances <5 kb display sufficient LD (delta>.3) to be useful in association studies. Results of the present study, if representative of the whole genome, suggest that a whole-genome scan searching for common disease-susceptibility alleles would require markers spaced < or = 5 kb apart.


Subject(s)
Chromosome Mapping , Genetic Predisposition to Disease/genetics , Linkage Disequilibrium/genetics , Phylogeny , Africa/ethnology , Alleles , Chromosome Mapping/methods , Chromosomes, Human, Pair 13/genetics , Chromosomes, Human, Pair 19/genetics , Chromosomes, Human, Pair 22/genetics , Demography , Finland/ethnology , Gene Frequency/genetics , Genetic Markers/genetics , Genotype , Humans , Jews/genetics , Polymorphism, Genetic/genetics , United Kingdom/ethnology
13.
Cancer Res ; 60(14): 3727-31, 2000 Jul 15.
Article in English | MEDLINE | ID: mdl-10919641

ABSTRACT

The RET tyrosine kinase is a functional receptor for neurotrophic ligands of the glial cell line-derived neurotrophic factor (GDNF) family. Loss of function of RET is associated with congenital megacolon or Hirschsprung's disease, whereas germ-line point mutations causing RET activation are responsible for multiple endocrine neoplasia type 2 (MEN2A, MEN2B, and familial medullary thyroid carcinoma) syndromes. Here we show that the expression of a constitutively active RET-MEN2A oncogene promotes survival of rat pheochromocytoma PC12 cells upon growth factor withdrawal. Moreover, we show that the RET-MEN2A-mediated survival depends on signals transduced by the phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) cascades. Thus, in PC12 cells, RET-MEN2A associates with the PI3K regulatory subunit p85 and promotes activation of Akt (also referred to as protein kinase B) in a PI3K-dependent fashion; in addition, RET-MEN2A promotes MAPK activation. PI3K recruitment and Akt activation as well as MAPK activation depend on RET-MEN2A tyrosine residue 1062. As a result, tyrosine 1062 of RET-MEN2A is essential for RET-MEN2A-mediated survival of PC12 cells cultured in growth factor-depleted media.


Subject(s)
Drosophila Proteins , MAP Kinase Signaling System , Protein Serine-Threonine Kinases , Proto-Oncogene Proteins/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , Tyrosine/metabolism , Animals , Blotting, Western , Cell Survival , Chromones/pharmacology , Culture Media, Serum-Free , DNA Fragmentation , Enzyme Activation , Enzyme Inhibitors/pharmacology , Flavonoids/pharmacology , Glial Cell Line-Derived Neurotrophic Factor Receptors , In Situ Nick-End Labeling , Ligands , Morpholines/pharmacology , Multiple Endocrine Neoplasia Type 2a/genetics , Multiple Endocrine Neoplasia Type 2a/metabolism , PC12 Cells , Phosphatidylinositol 3-Kinases/metabolism , Precipitin Tests , Protein Isoforms , Proto-Oncogene Proteins/chemistry , Proto-Oncogene Proteins c-akt , Proto-Oncogene Proteins c-ret , Rats , Receptor Protein-Tyrosine Kinases/chemistry , Signal Transduction , Transfection
14.
Int J Cancer ; 85(6): 845-9, 2000 Mar 15.
Article in English | MEDLINE | ID: mdl-10709106

ABSTRACT

In order to investigate the molecular basis of variation in response to ionising radiation (IR) in radiotherapy patients, we have studied the expression of several genes involved in DNA double-strand break repair pathways in fibroblast cell lines. Ten lines were established from skin biopsies of cancer patients with different normal-tissue reactions to IR, and 3 from a control individual. For all 10 test cell lines, the cellular radiosensitivity was also known. Using Western blots we measured, in non-irradiated cells, the basal expression levels of ATM, Rad1 and Hus1, involved in the control of cellular DNA damage checkpoints, together with DNA-PKcs, Ku70, Ku80; XRCC4, ligaseIV and Rad51, involved in radiation- induced DSB repair. We also analysed the in vitro enzymatic activities, under non-irradiated conditions, of the DNA-PK and XRCC4/ligaseIV complexes. The levels of expression of the different proteins were similar in all the cell lines, but the activities of the DNA-PK and XRCC4/ligaseIV complexes showed some differences. These differences did not correlate with either the normal tissue response of the patient in vivo or with cellular radiation sensitivity in vitro. The activity differences of these enzyme complexes, therefore, do not account for the variation of responses seen between patients.


Subject(s)
DNA Damage , DNA Repair , Gene Expression , Radiation Tolerance , Blotting, Western , DNA-Binding Proteins , Fibroblasts , Humans , Ligases , Neoplasms/pathology , Neoplasms/radiotherapy , Protein Kinases , Tumor Cells, Cultured
16.
Genes Chromosomes Cancer ; 25(4): 393-5, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10398434

ABSTRACT

Nijmegen breakage syndrome (NBS) is an autosomal recessive chromosomal instability syndrome characterized by microcephaly, growth retardation, immunodeficiency, and cancer predisposition. It shares a number of features with the Ataxia telangiectasia (AT) syndrome: the most notable are high sensitivity to ionizing radiation and predisposition to cancer. Recently, the gene responsible for NBS has been identified on chromosome band 8q21. It encodes a DNA double-strand break repair protein, named Nibrin. A truncating 5-bp deletion (657Del5) has been identified in 90% of NBS patients and this is presumed to be of Slavic origin. There is evidence that heterozygous AT mutation carriers are predisposed to breast cancer. Since the NBS phenotype at the cellular level is very similar to AT, we have screened 477 German breast cancer patients, aged under 51 years, and 866 matched controls for the common NBS mutation. We have identified one carrier among the cases and one among the controls, indicating that the population frequency of this NBS mutation is 1 in 866 people (95% CI = 1 in 34,376 to 1 in 156) and the estimated prevalence of NBS is thus 1 in 3 million people. The proportion of breast cancer attributable to this mutation is less than 1%. Genes Chromosomes Cancer 25:393-395, 1999.


Subject(s)
Breast Neoplasms/genetics , Chromosome Breakage/genetics , Fibrinogens, Abnormal/genetics , Nuclear Proteins , Sequence Deletion , Cell Cycle Proteins/genetics , Chromosomes, Human, Pair 8/genetics , Germany , Humans , Risk Factors , Syndrome
17.
Biochimie ; 81(4): 397-402, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10401675

ABSTRACT

The RET gene encodes a tyrosine kinase receptor for neurotrophic molecules. RET is a conceptually valuable example of how different mutations of a single gene may cause different diseases. Gene rearrangements activate the oncogenic potential of RET in human thyroid papillary carcinomas. On the other side, different point mutations activate RET in familial multiple endocrine neoplasia syndromes. Finally, inactivating mutations of RET can be present in Hirschsprung's disease patients. The detailed knowledge of the specific RET mutations responsible for human tumors provides relevant tools for the clinical management of these diseases. Moreover, the recent discovery of the growth factors which in vivo stimulate its signaling may shed new light on the role played by RET in the development and differentiation of the central and peripheral nervous system.


Subject(s)
Carcinoma, Papillary/genetics , Drosophila Proteins , Multiple Endocrine Neoplasia Type 2a/genetics , Multiple Endocrine Neoplasia Type 2b/genetics , Mutation , Proto-Oncogene Proteins/genetics , Receptor Protein-Tyrosine Kinases/genetics , Thyroid Neoplasms/genetics , Humans , Proto-Oncogene Proteins c-ret
18.
Cancer Res ; 59(5): 1120-6, 1999 Mar 01.
Article in English | MEDLINE | ID: mdl-10070972

ABSTRACT

The proto-oncogene RET encodes a transmembrane growth neurotrophic receptor with tyrosine kinase (TK) activity. RET mutations are associated with several human neoplastic and nonneoplastic diseases, including thyroid papillary carcinoma, multiple endocrine neoplasia type 2 syndromes, and Hirschsprung's disease. Activation of receptor TKs results in the binding and activation of downstream signaling proteins, among which are nonreceptor TKs of the Src family. To test the involvement of c-Src in Ret-mediated signaling, we measured the levels of c-Src activity in NIH3T3 cells coexpressing Ret and the accessory GFR alpha-1 receptor or an epidermal growth factor receptor/Ret chimeric receptor when the cells were stimulated by glial cell line-derived neurotrophic factor or epidermal growth factor, respectively. Ret stimulation resulted in the activation of c-Src. We also measured the levels of Src kinase activity in cell lines expressing isoforms of the Ret receptor activated by different mutations. These cells showed higher Src kinase activity than the normal counterpart. Furthermore, we show that Ret is able to associate with the SH2 domain of Src in a phosphotyrosine-dependent fashion. Microinjection of a kinase inactive mutant of c-Src blocked Ret-mediated mitogenic effect. These experiments demonstrate that activated Ret is able to bind and stimulate c-Src kinase and that Src activation is essential for the mitogenic activity of Ret.


Subject(s)
Cell Cycle , Drosophila Proteins , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins/metabolism , Proto-Oncogenes , Receptor Protein-Tyrosine Kinases/genetics , Receptor Protein-Tyrosine Kinases/metabolism , src-Family Kinases/metabolism , 3T3 Cells , Animals , Cell Line , Enzyme Activation , Glial Cell Line-Derived Neurotrophic Factor Receptors , Humans , Kinetics , Mice , Proto-Oncogene Mas , Proto-Oncogene Proteins c-ret , Recombinant Fusion Proteins/metabolism , S Phase , Signal Transduction , Transfection
19.
J Intern Med ; 243(6): 505-8, 1998 Jun.
Article in English | MEDLINE | ID: mdl-9681850

ABSTRACT

Cancer is a genetic disease caused by 'gain of function' mutations of oncogenes and 'loss of function' mutations of tumour suppressors and of genes involved in DNA repair mechanisms. The RET gene encodes a tyrosine kinase receptor for molecules belonging to the glial cell line-derived neurotrophic factor (GDNF) family. RET is a paradigmatic example of how different mutations of a single gene can lead to different neoplastic phenotypes. Indeed, gene rearrangements, often caused by chromosomal inversions, activate the oncogenic potential of RET in a fraction of human thyroid papillary carcinomas. On the other hand, different point mutations activate RET in familial multiple endocrine neoplasia syndromes familial medullary thyroid carcinoma (FMTC), MEN-2A and MEN-2B. Little information is so far available on the biochemical mechanisms by which the potent transforming and mitogenic signals of RET are delivered to the nucleus. However, recent data indicate coupling to the Shc-Ras-MAPK pathway as a necessary step in RET signal transduction.


Subject(s)
Drosophila Proteins , Multiple Endocrine Neoplasia Type 2a/genetics , Mutation , Proto-Oncogene Proteins/genetics , Receptor Protein-Tyrosine Kinases/genetics , Carcinoma, Papillary/genetics , Glial Cell Line-Derived Neurotrophic Factor Receptors , Humans , Multiple Endocrine Neoplasia Type 2a/enzymology , Protein-Tyrosine Kinases/genetics , Proto-Oncogene Proteins c-ret , Signal Transduction , Thyroid Neoplasms/genetics
20.
Endocrinology ; 139(8): 3613-9, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9681515

ABSTRACT

Ret is a receptor tyrosine kinase involved in several neoplastic and developmental diseases affecting the thyroid gland and tissues of neuroectodermal origin. Different ret mutations are associated with different disease phenotypes. Gain-of-function of ret is caused by gene rearrangements in thyroid papillary carcinomas and by point mutations in multiple endocrine neoplasia (MEN) type 2A syndrome (MEN2A), in familial medullary thyroid carcinoma (FMTC), and in the more severe MEN2B syndrome. Conversely, Hirschsprung's disease (HSCR) is associated with loss of function of ret. Recently, it has been shown that glial cell line-derived neurotrophic factor (GDNF), by binding to the accessory molecule GDNFR-alpha, acts as a functional ligand of Ret and stimulates its tyrosine kinase and biological activity. To ascertain whether the biological effects of ret mutations are modulated by GDNF, we have investigated the responsiveness to GDNF of ret mutants in cell lines coexpressing GDNFR-alpha and MEN2A-, MEN2B-, FMTC-, or HSCR-associated ret mutants. Here, we show that triggering of GDNF affected only ret/MEN2B, i.e. it stimulated ret/MEN2B mitogenic and kinase activities, as well as its ability to phosphorylate Shc, a bona fide Ret substrate. In contrast, ret mutants associated with MEN2A or FMTC (carrying Cys634 or Cys620 mutations) were unresponsive to GDNF. HSCR mutations, by affecting either the extracellular or the intracellular Ret domain, impaired responsiveness to GDNF. These data suggest that the phenotype of human diseases caused by ret mutations can be differentially influenced by GDNF.


Subject(s)
Adaptor Proteins, Signal Transducing , Adaptor Proteins, Vesicular Transport , Drosophila Proteins , Hirschsprung Disease/genetics , Multiple Endocrine Neoplasia Type 2a/genetics , Mutation , Nerve Growth Factors , Nerve Tissue Proteins/pharmacology , Proto-Oncogene Proteins/genetics , Receptor Protein-Tyrosine Kinases/genetics , 3T3 Cells , Animals , Cell Line , Glial Cell Line-Derived Neurotrophic Factor , Glial Cell Line-Derived Neurotrophic Factor Receptors , Humans , Immunosorbent Techniques , Mice , Nerve Tissue Proteins/genetics , Phosphatidylinositol Diacylglycerol-Lyase , Phosphorylation , Proteins/metabolism , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins c-ret , Receptor Protein-Tyrosine Kinases/metabolism , Recombinant Proteins , Shc Signaling Adaptor Proteins , Signal Transduction , Src Homology 2 Domain-Containing, Transforming Protein 1 , Transfection , Type C Phospholipases/pharmacology , Tyrosine/metabolism
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