Coupling lipid synthesis with nuclear envelope remodeling.

The nuclear envelope (NE) is a protective barrier to the genome, yet its membranes undergo highly dynamic remodeling processes that are necessary for cell growth and maintenance. While mechanisms by which proteins promote NE remodeling are emerging, the types of bilayer lipids and the lipid-protein interactions that define and sculpt nuclear membranes remain elusive. The NE is continuous with the endoplasmic reticulum (ER) and recent evidence suggests that lipids produced in the ER are harnessed to remodel nuclear membranes. In this review, we examine new roles for lipid species made proximally within the ER and locally at the NE to control NE dynamics. We further explore how the biosynthesis of lipids coordinates NE remodeling to ensure genome protection.

The Saccharomyces cerevisiae Spo7 basic tail is required for Nem1-Spo7/Pah1 phosphatase cascade function in lipid synthesis.

The Saccharomyces cerevisiae Nem1-Spo7 protein phosphatase complex dephosphorylates and thereby activates Pah1 at the nuclear/endoplasmic reticulum membrane. Pah1, a phosphatidate phosphatase catalyzing the dephosphorylation of phosphatidate to produce diacylglycerol, is one of the most highly regulated enzymes in lipid metabolism. The diacylglycerol produced in the lipid phosphatase reaction is utilized for the synthesis of triacylglycerol that is stored in lipid droplets. Disruptions of the Nem1-Spo7/Pah1 phosphatase cascade cause a plethora of physiological defects. Spo7, the regulatory subunit of the Nem1-Spo7 complex, is required for the Nem1 catalytic function and interacts with the acidic tail of Pah1. Spo7 contains three conserved homology regions (CR1-3) that are important for the interaction with Nem1, but its region for the interaction with Pah1 is unknown. Here, by deletion and site-specific mutational analyses of Spo7, we revealed that the C-terminal basic tail (residues 240-259) containing five arginine and two lysine residues is important for the Nem1-Spo7 complex-mediated dephosphorylation of Pah1 and its cellular function (triacylglycerol synthesis, lipid droplet formation, maintenance of nuclear/endoplasmic reticulum membrane morphology, and cell growth at elevated temperatures). The glutaraldehyde cross-linking analysis of synthetic peptides indicated that the Spo7 basic tail interacts with the Pah1 acidic tail. This work advances our understanding of the Spo7 function and the Nem1-Spo7/Pah1 phosphatase cascade in yeast lipid synthesis.

Conserved regions of the regulatory subunit Spo7 are required for Nem1-Spo7/Pah1 phosphatase cascade function in yeast lipid synthesis.

In the yeast Saccharomyces cerevisiae, the Nem1-Spo7 complex is a protein phosphatase that activates Pah1 phosphatidate phosphatase at the nuclear-endoplasmic reticulum membrane for the synthesis of triacylglycerol. The Nem1-Spo7/Pah1 phosphatase cascade largely controls whether phosphatidate is partitioned into the storage lipid triacylglycerol or into membrane phospholipids. The regulated synthesis of the lipids is crucial for diverse physiological processes during cell growth. Spo7 in the protein phosphatase complex is required as a regulatory subunit for the Nem1 catalytic subunit to dephosphorylate Pah1. The regulatory subunit contains three conserved homology regions (CR1, CR2, and CR3). Previous work showed that the hydrophobicity of LLI (residues 54-56) within CR1 is important for Spo7 function in the Nem1-Spo7/Pah1 phosphatase cascade. In this work, by deletion and site-specific mutational analyses, we revealed that CR2 and CR3 are also required for Spo7 function. Mutations in any one of the conserved regions were sufficient to disrupt the function of the Nem1-Spo7 complex. We determined that the uncharged hydrophilicity of STN (residues 141-143) within CR2 was required for Nem1-Spo7 complex formation. In addition, the hydrophobicity of LL (residues 217 and 219) within CR3 was important for Spo7 stability, which indirectly affected complex formation. Finally, we showed the loss of Spo7 CR2 or CR3 function by the phenotypes (e.g., reduced amounts of triacylglycerol and lipid droplets, temperature sensitivity) that are attributed to defects in membrane translocation and dephosphorylation of Pah1 by the Nem1-Spo7 complex. These findings advance knowledge of the Nem1-Spo7 complex and its role in lipid synthesis regulation.

Phosphatidic Acid Mediates the Nem1-Spo7/Pah1 Phosphatase Cascade in Yeast Lipid Synthesis.

In the yeast Saccharomyces cerevisiae, the PAH1-encoded Mg2+-dependent phosphatidate (PA) phosphatase Pah1 regulates the bifurcation of PA to diacylglycerol (DAG) for triacylglycerol (TAG) synthesis and to CDP-DAG for phospholipid synthesis. Pah1 function is mainly regulated via control of its cellular location by phosphorylation and dephosphorylation. Pah1 phosphorylated by multiple protein kinases is sequestered in the cytosol apart from its substrate PA in the membrane. The phosphorylated Pah1 is then recruited and dephosphorylated by the protein phosphatase complex Nem1 (catalytic subunit)-Spo7 (regulatory subunit) in the endoplasmic reticulum. The dephosphorylated Pah1 hops onto and scoots along the membrane to recognize PA for its dephosphorylation to DAG. Here, we developed a proteoliposome model system that mimics the Nem1-Spo7/Pah1 phosphatase cascade to provide a tool for studying Pah1 regulation. Purified Nem1-Spo7 was reconstituted into phospholipid vesicles prepared in accordance with the phospholipid composition of the nuclear/endoplasmic reticulum membrane. The Nem1-Spo7 phosphatase reconstituted in the proteoliposomes, which were measured 60 nm in an average diameter, was catalytically active on Pah1 phosphorylated by Pho85-Pho80, and its active site was located at the external side of the phospholipid bilayer. Moreover, we determined that PA stimulated the Nem1-Spo7 activity, and the regulatory effect was governed by the nature of the phosphate headgroup but not by the fatty acyl moiety of PA. The reconstitution system for the Nem1-Spo7/Pah1 phosphatase cascade, which starts with the phosphorylation of Pah1 by Pho85-Pho80 and ends with the production of DAG, is a significant advance to understand a regulatory cascade in yeast lipid synthesis.

Yeast phosphatidic acid phosphatase Pah1 hops and scoots along the membrane phospholipid bilayer.

PA phosphatase, encoded by PAH1 in the yeast Saccharomyces cerevisiae, catalyzes the Mg2+-dependent dephosphorylation of PA, producing DAG at the nuclear/ER membrane. This enzyme plays a major role in triacylglycerol synthesis and in the regulation of phospholipid synthesis. As an interfacial enzyme, PA phosphatase interacts with the membrane surface, binds its substrate, and catalyzes its reaction. The Triton X-100/PA-mixed micellar system has been utilized to examine the activity and regulation of yeast PA phosphatase. This system, however, does not resemble the in vivo environment of the membrane phospholipid bilayer. We developed an assay system that mimics the nuclear/ER membrane to assess PA phosphatase activity. PA was incorporated into unilamellar phospholipid vesicles (liposomes) composed of the major nuclear/ER membrane phospholipids, PC, PE, PI, and PS. We optimized this system to support enzyme-liposome interactions and to afford activity that is greater than that obtained with the aforementioned detergent system. Activity was regulated by phospholipid composition, whereas the enzyme's interaction with liposomes was insensitive to composition. Greater activity was attained with large (≥100 nm) versus small (50 nm) vesicles. The fatty-acyl moiety of PA had no effect on this activity. PA phosphatase activity was dependent on the bulk (hopping mode) and surface (scooting mode) concentrations of PA, suggesting a mechanism by which the enzyme operates along the nuclear/ER membrane in vivo.

[Inherited tumor syndromes of gastroenteropancreatic and thoracic neuroendocrine neoplasms]. / Syndromes de prédisposition aux tumeurs neuroendocrines gastro-entéro-pancréatiques et thoraciques.

About 5% of gastroenteropancreatic and thoracic neuroendocrine neoplasms (NENs) arise in the context of an inherited tumour syndrome. The two most frequent syndromes are: multiple endocrine neoplasia type 1 (MEN1), associated with a large spectrum of endocrine and non endocrine tumours, including duodenopancreatic, thymic and bronchial NENs, and the von Hippel-Lindau syndrome VHL, associated with pancreatic NENs. Two inherited syndromes have a low incidence of NENs: neurofibromatosis type 1 (NF1), associated with duodenal somatostatinomas, and tuberous sclerosis (TSC), associated with pancreatic NENs. Two rare syndromes have a high incidence of NENs: multiple endocrine neoplasia type 4 (MEN4), with a tumour spectrum similar to that of MEN1, and glucagon cell hyperplasia neoplasia (GCHN), involving only the pancreas. It is likely that other syndromes remain to be characterized, especially in familial small-intestinal NENs. The diagnosis is usually raised because of the suggestive clinical setting: young age at diagnosis, multiple tumours in multiple organs, familial history. Except in VHL and NF1, tumours themselves do not show specific pathological features; they usually are well differentiated and of low histological grade; their prognosis is good, except for MEN1-associated thymic NENs. The most suggestive pathological feature is their combination with various endocrine and/or non endocrine lesions in the adjacent tissue. Pathological examination is important, for a correct diagnosis and for an accurate management of the patients and their families, who must be referred to expert centers.

Fat-regulating phosphatidic acid phosphatase: a review of its roles and regulation in lipid homeostasis.

Phosphatidic acid (PA) phosphatase is an evolutionarily conserved enzyme that plays a major role in lipid homeostasis by controlling the cellular levels of its substrate, PA, and its product, diacylglycerol. These lipids are essential intermediates for the synthesis of triacylglycerol and membrane phospholipids; they also function in lipid signaling, vesicular trafficking, lipid droplet formation, and phospholipid synthesis gene expression. The importance of PA phosphatase to lipid homeostasis and cell physiology is exemplified in yeast, mice, and humans by a host of cellular defects and lipid-based diseases associated with loss or overexpression of the enzyme activity. In this review, we focus on the mode of action and regulation of PA phosphatase in the yeast Saccharomyces cerevisiae The enzyme Pah1 translocates from the cytosol to the nuclear/endoplasmic reticulum membrane through phosphorylation and dephosphorylation. Pah1 phosphorylation is mediated in the cytosol by multiple protein kinases, whereas dephosphorylation is catalyzed on the membrane surface by an integral membrane protein phosphatase. Posttranslational modifications of Pah1 also affect its catalytic activity and susceptibility to degradation by the proteasome. Additional mechanistic understanding of Pah1 regulation should be instrumental for the identification of small-molecule inhibitors or activators that can fine-tune PA phosphatase function and thereby restore lipid homeostasis.

Protein kinase A phosphorylates the Nem1-Spo7 protein phosphatase complex that regulates the phosphorylation state of the phosphatidate phosphatase Pah1 in yeast.

The Nem1-Spo7 protein phosphatase plays a role in lipid synthesis by controlling the membrane localization of Pah1, the diacylglycerol-producing phosphatidate (PA) phosphatase that is crucial for the synthesis of triacylglycerol in the yeast Saccharomyces cerevisiae By dephosphorylating Pah1, Nem1-Spo7 facilitates its translocation to the nuclear/endoplasmic reticulum membrane for catalytic activity. Like its substrate Pah1, Nem1-Spo7 is phosphorylated in the cell, but the specific protein kinases involved remain to be identified. In this study, we demonstrate that the Nem1-Spo7 complex is phosphorylated by protein kinase A (PKA), which is associated with active cell growth, metabolic activity, and membrane phospholipid synthesis. In vitro phosphorylation of purified Nem1-Spo7 and of their synthetic peptides revealed that both subunits of the phosphatase complex are PKA substrates. Using phosphoamino acid and phosphopeptide-mapping analyses coupled with site-directed mutagenesis, we identified Ser-140 and Ser-210 of Nem1 and Ser-28 of Spo7 as PKA-targeted phosphorylation sites. Immunodetection of the phosphatase complex from the cell with anti-PKA substrate antibody confirmed the in vivo phosphorylations of Nem1 and Spo7 on the serine residues. Lipid-labeling analysis of cells bearing phosphorylation-deficient alleles of NEM1 and SPO7 indicated that the PKA phosphorylation of the phosphatase complex stimulates phospholipid synthesis and attenuates the synthesis of triacylglycerol. This work advances the understanding of how PKA-mediated posttranslational modifications of Nem1 and Spo7 regulate lipid synthesis in yeast.

The TORC1-Nem1/Spo7-Pah1/lipin axis regulates microautophagy induction in budding yeast.

Nutrient starvation and inactivation of target of rapamycin complex 1 (TORC1) protein kinase promotes macroautophagy. Macroautophagy is a lipid-consuming process, and Nem1/Spo7 protein phosphatase and Pah1/lipin phosphatidate phosphatase are activated after TORC1 inactivation, supporting macroautophagy induction in the budding yeast Saccharomyces cerevisiae. On the other hand, whether and how microautophagy, which also consumes lipids, is regulated by TORC1 is controversial. Here we show that TORC1 inactivation induces microautophagy in budding yeast. Vps27, but not Atg1, Atg7, or Atg8, was required for TORC1 inactivation-induced microautophagy. Furthermore, the Nem1/Spo7-Pah1 axis was also critical for microautophagy induction. Thus, the TORC1-Nem1/Spo7-Pah1 axis is a master regulator of not only macroautophagy but also microautophagy in budding yeast.

Phosphorylation of lipid metabolic enzymes by yeast protein kinase C requires phosphatidylserine and diacylglycerol.

Protein kinase C in Saccharomyces cerevisiae, i.e., Pkc1, is an enzyme that plays an important role in signal transduction and the regulation of lipid metabolic enzymes. Pkc1 is structurally similar to its counterparts in higher eukaryotes, but its requirement of phosphatidylserine (PS) and diacylglycerol (DAG) for catalytic activity has been unclear. In this work, we examined the role of these lipids in Pkc1 activity with protein and peptide substrates. In agreement with previous findings, yeast Pkc1 did not require PS and DAG for its activity on the peptide substrates derived from lipid metabolic proteins such as Pah1 [phosphatidate (PA) phosphatase], Nem1 (PA phosphatase phosphatase), and Spo7 (protein phosphatase regulatory subunit). However, the lipids were required for Pkc1 activity on the protein substrates Pah1, Nem1, and Spo7. Compared with DAG, PS had a greater effect on Pkc1 activity, and its dose-dependent interaction with the protein kinase was shown by the liposome binding assay. The Pkc1-mediated degradation of Pah1 was attenuated in the cho1Δ mutant, which is deficient in PS synthase, supporting the notion that the phospholipid regulates Pkc1 activity in vivo.

[Two cases reports of pancreatic endocrine microadenoma incidentally found]. / Découverte fortuite de micro-adénome endocrine pancréatique : à propos de deux cas.

A 59-year-old male, was admitted to our hospital for a tumor of the pancreatic tail. Serum CEA and CA 19-9 levels were normal. Splenopancreasectomy found a desmoid tumour. A 69-year-old male was referred to our institution for chronic anemia and inflammatory syndrome with splenomegaly. Splenectomy showed an important splenic congestion and siderosis. Both patients had a type 2 diabetes mellitus. Furthermore, histological examination revealed pancreatic endocrine microadenomas. The two patients' postoperative course was unremarkable. Eleven and 24 months respectively after the diagnosis, the patients are alive and well, with no tumor recurrence.

Phosphorylation-mediated regulation of the Nem1-Spo7/Pah1 phosphatase cascade in yeast lipid synthesis.

The PAH1-encoded phosphatidate phosphatase, which catalyzes the dephosphorylation of phosphatidate to produce diacylglycerol, controls the divergence of phosphatidate into triacylglycerol synthesis and phospholipid synthesis. Pah1 is inactive in the cytosol as a phosphorylated form and becomes active on the nuclear/endoplasmic reticulum membrane as a dephosphorylated form by the Nem1-Spo7 protein phosphatase complex. The phosphorylation of Pah1 by protein kinases, which include casein kinases I and II, Pho85-Pho80, Cdc28-cyclin B, and protein kinases A and C, controls its cellular location, catalytic activity, and susceptibility to proteasomal degradation. Nem1 (catalytic subunit) and Spo7 (regulatory subunit), which form a protein phosphatase complex catalyzing the dephosphorylation of Pah1 for its activation, are phosphorylated by protein kinases A and C. In this review, we discuss the functions and interrelationships of the protein kinases in the control of the Nem1-Spo7/Pah1 phosphatase cascade and lipid synthesis.

Lipid droplet biogenesis from specialized ER subdomains.

Lipid droplets (LDs) are cellular compartments dedicated to the storage of metabolic energy in the form of neutral lipids, commonly known as "fat". The biogenesis of LDs takes place in the endoplasmic reticulum (ER), but its spatial and temporal organization is poorly understood. How exactly sites of LD formation are selected and the succession of proteins and lipids needed to mediate this process remains to be defined. In our current study we show that the yeast triacylglycerol (TAG)-synthases, Lro1 and Dga1 get recruited to discrete ER subdomains where they initiate TAG synthesis and hence LD formation (Choudhary et al. (2020), J Cell Biol). These ER subdomains are defined by yeast seipin, Fld1, and a regulator of diacylglycerol (DAG) production, Nem1. Both Fld1 and Nem1 are ER proteins which localize at contact sites between the ER and LDs. Interestingly, even in cells lacking LDs, Fld1 and Nem1 show punctate localization at ER subdomains independently of each other, but they are required together to recruit the TAG-synthases and hence create functional sites of LD biogenesis. Fld1/Nem1-containing ER subdomains recruit additional LD biogenesis factors, such as Yft2, Pex30, Pet10 and Erg6, and these membrane domains become enriched in DAG. In conclusion, Fld1 and Nem1 play a crucial role in defining ER subdomains for the recruitment of proteins and lipids needed to initiate LD biogenesis.

Comparison of 68Ga-Dotatate PET/CT and 18F-FDOPA PET/CT for the diagnosis of pancreatic neuroendocrine tumors in a MEN1 patient.

CONTEXT: Pancreatic neuroendocrine tumors (PNETs) occur in more than 80% of patients with multiple endocrine neoplasia type 1 (MEN1) syndrome, with predominance of small (<1cm) non-functioning tumors, followed by gastrinomas and insulinomas. Due to their small size, the diagnostic performance of conventional MRI and CT imaging is highly variable, with a real risk of false-negatives. Functional imaging on 111In-DTPA-Octreotide SPECT somatostatin receptor scintigraphy (Octreoscan®) is the modality of choice, but shows only 80% sensitivity. Alternatively, 18F-fluorodihydroxyphenylalanine (FDOPA) and, more recently, 68Ga-Dotatate PET/CT imaging are valuable options in case of negative Octreoscan®. CASE REPORT: A 55 old-year woman diagnosed with MEN1 syndrome, presented with multiple asymptomatic but progressive PNETs revealed on ultrasound endoscopy. Octreoscan® was negative, as was 18F-FDOPA PET/CT, whereas 68Ga-Dotatate PET/CT detected all PNETs found on endoscopy. CONCLUSION: We here report the first case of a MEN1 patient who successfully underwent a 68Ga-Dotatate PET/CT for detection and follow-up of PNETs, while both Octreoscan® and 18F-FDOPA PET/CT were negative.

[Multiple endocrine neoplasia type 1: about a case]. / Néoplasie endocrinienne multiple type 1: à propos d'un cas.

Multiple endocrine neoplasia type 1 (MEN1) is a rare disease, defined as a tumor developing in at least two endocrine glands including the anterior pituitary gland, the parathyroid glands and the duodenopancreatic endocrine tissue. This disorder, inherited in an autosomal dominant pattern, is caused by mutations in the MEN1 gene encoding the tumor suppressor menin and located on chromosome 11q13. However, sporadic cases account for 8-14%. The first endocrine lesion may be solitary in approximately 75% of cases. However, all major alterations can be inaugural. We here report a case of multiple endocrine neoplasia type 1 revealed by aggressive somatoprolactinic pituitary adenoma which didn't respond to conventional treatment. The detection of primary hyperparathyroidism as well as neuroendocrine tumor of the pancreas seven years later make this a very particular case. Therapeutic options are discussed within the multidisciplinary team specialized in endocrine diseases.

Phenotype and genotype of patients with multiple endocrine neoplasia type 1 studied in Argentina / Fenotipo y genotipo de pacientes con neoplasia endocrina múltiple tipo 1 estudiados en Argentina

Abstract Introduction: Multiple Endocrine Neoplasia type 1 (MEN1) is an autosomal dominant inherited disease with an estimated prevalence of 2-10:100 000. The main locations of tumors are parathyroid glands (HPT), gas troenteropancreatic tract (GEPT), and anterior pituitary gland (PT). The aim of our investigation was to describe the phe notype and genotype of Argentinian patients with MEN1. Methods: A total of 68 index patients diagnosed with at least two of the three main tumors or one tumor and a relative with MEN1, and 84 first-degree relatives were studied. We sequenced the coding region (exons 2-10); the promoter, exon 1; and the flanking intronic regions of the MEN1 gene, following the Sanger method. We used MLPA in index patients without mutation. Results: Prevalence of tumors: HPT 87.5%, GEPT 49% (p< 0.001). No statistical differences in the prevalence of HPT vs. PT (68%). Prevalence of pathogenic variants: 90% in familial cases and 51% in sporadic cases. Of the different 36 pathogenic variants, 13 (36.2%) were frameshift micro-rearrangement, 8 (22.2%) were mis sense, 9 (25%) were nonsense, 3 (8.3%) were mutations in splicing sites, 2 (5.5%) were large deletions and, 1 in-frame micro-rearrangement. We found 7 novel pathogenic variants. Thirty-nine percent (n = 33) of first-degree relatives of 23 families were found to be mutation carriers. Conclusion: The phenotype and genotype of Argen tinian patients was similar to other MEN1 populations. A high frequency of PT and the identification of seven novel mutations are underscored.

Resumen Introducción: La neoplasia endocrina múltiple tipo 1 (NEM1) es una enfermedad hereditaria autosómica dominante con una prevalencia estimada de 2-10:100 000. Las localizaciones principales de los tumores son glándulas paratiroides (HPT), tracto gastroenteropan creático (TGEP) y glándula pituitaria (TP). El objetivo de nuestra investigación fue describir el fenotipo y genotipo de pacientes argentinos con NEM1. Métodos: Estudiamos 68 casos índices diagnostica dos por presentar al menos dos de los tres tumores principales, o un tumor y un pariente con NEM1, y 84 familiares de primer grado. Secuenciamos la región codificante (exones 2-10); el promotor, exón 1; y las re giones intrónicas flanqueantes del gen MEN1 siguiendo el método de Sanger. Utilizamos MLPA en pacientes índice sin mutación. Resultados: Prevalencia de tumores: HPT 87.5%, TGEP 49% (p < 0.001), sin diferencias estadísticas entre las prevalencias de HPT vs TP (68%). Prevalencia de variantes patogénicas: 90% en casos familiares y 51% en esporádi cos. Hallamos 36 variantes patogénicas, 7 (20%) fueron noveles. Fueron 13 (36.2%) microarreglos con cambio en el marco de lectura, 9 (25%) variantes sin sentido, 8 (22.2%) con cambio de sentido, 3 (8.3%) en sitio de unión de empalme, 2 (5.5%) grandes deleciones y 1 microarre glo sin cambio en el marco de lectura. El 39 % (n = 33) de los parientes de primer grado en 23 familias fueron portadores de mutaciones. Conclusión: El fenotipo y genotipo de los pacientes argentinos con NEM1 fue similar al de otras poblaciones. Destacamos una alta frecuencia de TP y de variaciones patogénicas noveles.

The Nem1/Spo7-Pah1/lipin axis is required for autophagy induction after TORC1 inactivation.

Autophagy is a process that requires intense membrane remodeling and consumption. The nutrient-responsive TORC1 (target of rapamycin complex 1) kinase regulates autophagy. However, how TORC1 controls autophagy via lipid/membrane biogenesis is unknown. TORC1 regulates the function of yeast phosphatidate phosphatase lipin Pah1 via the Nem1/Spo7 phosphatase complex. Here, we show that the Nem1/Spo7-Pah1 axis is required for autophagy induction after TORC1 inactivation and survival during starvation. Furthermore, this axis was critical for nucleophagy (both micronucleophagy and macronucleophagy) and was required for proper localization of micronucleophagy factor Nvj1 and macronucleophagy receptor Atg39. This study indicated that the Nem1/Spo7-Pah1 axis controlled by TORC1 is a critical branch for autophagy induction in nutrient starvation conditions.

[Primary hyperparathyroidism: new concepts, new recommendations]. / Hyperparathyroïdie primaire: nouveaux concepts, nouvelles recommandations.

Today, primary hyperparathyroidism (PHPT) is frequently diagnosed at an asymptomatic stage. New international guidelines presented at the Endocrine Society congress update the management of this disease. Normocalcemic PHPT is part of the diagnostic spectrum of PHPT, its natural history is poorly known, and monitoring is proposed once secondary HPT has been eliminated. Bone involvement, classically predominant in cortical bone, also affects trabecular bone. Osteodensitometry is poorly effective at the vertebral level and new methods (trabecular bone score [TBS], vertebral fracture assessment [VFA]) should improve the assessment of the risk of fracture. The kidney is the most frequently symptomatic organ, and an imaging workup as well as urinary tests are recommended in all patients when searching for causes of lithiasis or nephrocalcinosis. More than 10% of PHPT cases are related to a germinal mutation: these patients should be identified to optimize their management and that of their relatives. Medical treatment is reserved for patients for whom surgery is not indicated or possible: cinacalcet is effective for calcemia, the bisphosphonates are effective for bone involvement. Vitamin D deficiency can be corrected as long as calcemia and creatinuria are monitored. Surgical treatment is recommended in case of pronounced hypercalcemia, bone or renal involvement, and age less than 50 years and in patients in whom monitoring is refused or impossible. Studies have shown that asymptomatic PHPT evolves little in monitored patients.

The impact of clinical and genetic screenings on the management of the multiple endocrine neoplasia type 1

PURPOSE: To perform clinical and genetic screening for multiple endocrine neoplasia type 1 (MEN1) in patients at the Academic Hospital of the University of São Paulo School of Medicine, and to analyze its impact on clinical management of patients with MEN1. METHODS: The clinical diagnosis of MEN1 was made in accordance with the Consensus on multiple endocrine neoplasias. Mutation analysis of the entire MEN1 tumor suppressor gene and genetic screening of at-risk family members were performed by direct sequencing. To analyze the implementation of genetic diagnosis, the studied patients were separated into 3 groups: MEN1 index cases (group I), clinically diagnosed MEN1 cases (group II), and genetically diagnosed MEN1 cases (group III). RESULTS: In total, 154 individuals were clinically and genetically studied. We identified 12 different MEN1 mutations. Fifty-two MEN1 cases were identified: 13 in group I, 28 in group II, and 11 in group III. The mean age in group III (27.0 years) was significantly lower than in groups I (39.5 years) and II (42.4 years; P = 0.03 and P = 0.01, respectively). Patients in groups I and II mostly presented 2 or 3 MEN1-related tumors, while 81.8 percent of those in group III presented 1 or no MEN1-related tumor. Additionally, in group III, 45.4 percent of cases were asymptomatic, and no metastasis or death was verified. Surveillance for MEN1 mutations allowed the exclusion of 102 noncarriers, including a case of MEN1 phenocopy. CONCLUSION: Our data supports the benefits of clinical and genetic screening for multiple endocrine neoplasia type 1 in the management of this syndrome.

OBJETIVOS: Realizar rastreamentos clínico e gênico para Neoplasia Endócrina Múltipla tipo 1 (NEM1) e analisar seu impacto no seguimento clínico desses pacientes no Hospital das Clínicas, SP. MÉTODOS: O diagnóstico clínico de NEM1 foi realizado de acordo com o Consenso sobre neoplasias endócrinas múltiplas. A análise genética para identificação de mutações foi realizada por sequenciamento automático de todas as regiões codificadoras e fronteiras exon/intron do gene MEN1. Os casos afetados foram sub-divididos em 3 grupos e analisados separadamente: casos-índices (grupo I), familiares diagnosticados clinicamente (grupo II) e genicamente (grupo III). RESULTADOS: Um total de 154 casos participou desse estudo, sendo 52 diagnosticados com NEM1: 13 do grupo I, 28 do grupo II e 11 do grupo III. A idade média ao diagnóstico no grupo III (27 anos) foi significativamente menor que a dos grupos I (39,5 anos; p = 0,03) e II (42,4 anos; p = 0,01). A maioria dos pacientes dos grupos I e II apresentou 2 ou 3 tumores, enquanto que 81,8 por cento dos casos do grupo III apresentavam 1 ou nenhum tumor relacionado à NEM1. Além disto, 45,4 por cento dos casos do grupo III eram assintomáticos, não sendo observados nenhuma metástase ou óbito. Os demais 102 familiares sob-risco estudados não herdaram mutação MEN1 e foram excluídos do rastreamento clínico. Um caso de fenocópia NEM1 foi também localizado. DISCUSSÃO: Nossos dados demonstraram importantes benefícios no seguimento dos pacientes NEM1, obtidos pela implementação dos rastreamentos clínico e gênico para essa doença.