RESUMO
BACKGROUND: Maturity-onset diabetes of the young (MODY) is a form of monogenic diabetes with autosomal dominant inheritance. To date, mutations in 11 genes have been frequently associated with this phenotype. In Brazil, few cohorts have been screened for MODY, all using a candidate gene approach, with a high prevalence of undiagnosed cases (MODY-X). METHODS: We conducted a next-generation sequencing target panel (tNGS) study to investigate, for the first time, a Brazilian cohort of MODY patients with a negative prior genetic analysis. One hundred and two patients were selected, of which 26 had an initial clinical suspicion of MODY-GCK and 76 were non-GCK MODY. RESULTS: After excluding all benign and likely benign variants and variants of uncertain significance, we were able to assign a genetic cause for 12.7% (13/102) of the probands. Three rare MODY subtypes were identified (PDX1/NEUROD1/ABCC8), and eight variants had not been previously described/mapped in genomic databases. Important clinical findings were evidenced in some cases after genetic diagnosis, such as MODY-PDX1/HNF1B. CONCLUSION: A multiloci genetic approach allowed the identification of rare MODY subtypes, reducing the large percentage of MODY-X in Brazilian cases and contributing to a better clinical, therapeutic, and prognostic characterization of these rare phenotypes.
Assuntos
Diabetes Mellitus Tipo 2/genética , Testes Genéticos/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Adolescente , Adulto , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Brasil , Estudos de Coortes , Feminino , Predisposição Genética para Doença , Proteínas de Homeodomínio/genética , Humanos , Masculino , Análise de Sequência de DNA , Receptores de Sulfonilureias/genética , Transativadores/genética , Adulto JovemRESUMO
Acyl-CoA synthetase-4 (ACSL4) is an enzyme implicated in estrogen receptor α (ERα) negative regulation and hormone therapy resistance in breast cancer. In addition, ACSL4 has been associated to certain types of hormone resistance in prostate cancer. Chemotherapeutic treatment of disseminated breast cancer is usually faced with therapy resistance associated to ATP-binding cassette (ABC) transporter expression, which detect and eject anti-cancer drugs from cells. In this context, the aim of the present work was to study the role of ACSL4 in anti-cancer drug resistance and the involvement of ABC transporters in the underlying mechanisms. To this end, we used MCF-7 Tet-Off/ACSL4 and MDA-MB-231 mock cells, which overexpress ACSL4, and control line MCF-7 Tet-Off empty vector, MDA-MB-231 shRNA ACSL4 and MDA-MB-231 wild type cells. Assays were conducted on cell viability (MTT), cell proliferation (BrdU), drug efflux (flow cytometry), ACSL4-responsive drug resistance ABC transporter genes (RNA-Seq), transporter mRNA expression, protein levels and signaling pathway participation (real-time PCR and Western blot). Higher survival rates upon chemotherapeutic treatment were obtained in MCF-7 Tet-Off/ACSL4 and MDA-MB-231 mock cells, an effect counteracted by doxycycline- or shRNA-induced ACSL4 inhibition, respectively. A synergic effect of ACSL4 inhibitor triacsin C and chemotherapeutic drugs was observed on the inhibition of MDA-MB-231 wild type cell proliferation. MCF-7 Tet-Off/ACSL4 cells showed greater doxorubicin, Hoechst 33342 and calcein AM efflux. In contrast, MDA-MB-231 shRNA ACSL4 cells evidenced inhibition of chemotherapeutic drug efflux. ABCG2, ABCC4, and ABCC8 were identified as ACSL4-responsive drug resistance genes whose expression was increased in MCF-7 Tet-Off/ACSL4 cells but inhibited in MDA-MB-231 shRNA ACSL4 cells. Further cell survival assays in the presence of Ko 143 and Ceefourin 1, inhibitors of ABCG2 and ABCC4, respectively, upon chemotherapeutic treatment showed greater participation of ABCG2 in anti-cancer drug resistance in cells overexpressing ACSL4. In addition, ACSL4 inhibition and chemotherapeutic treatment combined with rapamycin-induced mTOR inhibition synergically inhibited proliferation and reduced ABCG2 expression in cells overexpressing ACSL4. In sum, ACSL4 may be regarded as a novel therapeutic target regulating the expression of transporters involved in anticancer drug resistance through the mTOR pathway to restore drug sensitivity in tumors with poor prognosis for disease-free and overall survival.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Coenzima A Ligases/metabolismo , Resistencia a Medicamentos Antineoplásicos/fisiologia , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Antineoplásicos/farmacologia , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cisplatino/farmacologia , Coenzima A Ligases/genética , Doxorrubicina/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Humanos , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Receptores de Sulfonilureias/genética , Receptores de Sulfonilureias/metabolismo , Triazenos/farmacologiaRESUMO
Congenital hyperinsulinism (CHI) is a heterogenous disease caused by insulin secretion regulatory defects, being ABCC8/KCNJ11 the most commonly affected genes. Therapeutic options include diazoxide, somatostatin analogues and surgery, which is curative in focal CHI. We report the case of two siblings (born two years apart) that presented themselves with hypoketotic hyperinsulinemic persistent hypoglycemias during neonatal period. The diagnosis of diffuse CHI due to an ABCC8 compound mutation (c.3576delG and c.742C>T) was concluded. They did not benefit from diazoxide therapy (or pancreatectomy performed in patient number 1) yet responded to somatostatin analogues. Patient number 1 developed various neurological deficits (including epilepsy), however patient number 2 experienced an entirely normal neurodevelopment. We believe this case shows how previous knowledge of the firstborn sibling's disease contributed to a better and timelier medical care in patient number 2, which could potentially explain her better neurological outcome despite their same genotype.
Assuntos
Hiperinsulinismo Congênito/genética , Hiperinsulinismo Congênito/terapia , Mutação/genética , Irmãos , Receptores de Sulfonilureias/genética , Diazóxido/uso terapêutico , Feminino , Genótipo , Humanos , Recém-Nascido , Masculino , Pancreatectomia/métodos , Fenótipo , Somatostatina/análise , Resultado do TratamentoRESUMO
SUMMARY Congenital hyperinsulinism (CHI) is a heterogenous disease caused by insulin secretion regulatory defects, being ABCC8/KCNJ11 the most commonly affected genes. Therapeutic options include diazoxide, somatostatin analogues and surgery, which is curative in focal CHI. We report the case of two siblings (born two years apart) that presented themselves with hypoketotic hyperinsulinemic persistent hypoglycemias during neonatal period. The diagnosis of diffuse CHI due to an ABCC8 compound mutation (c.3576delG and c.742C>T) was concluded. They did not benefit from diazoxide therapy (or pancreatectomy performed in patient number 1) yet responded to somatostatin analogues. Patient number 1 developed various neurological deficits (including epilepsy), however patient number 2 experienced an entirely normal neurodevelopment. We believe this case shows how previous knowledge of the firstborn sibling's disease contributed to a better and timelier medical care in patient number 2, which could potentially explain her better neurological outcome despite their same genotype.
Assuntos
Humanos , Masculino , Feminino , Recém-Nascido , Irmãos , Hiperinsulinismo Congênito/genética , Hiperinsulinismo Congênito/terapia , Receptores de Sulfonilureias/genética , Mutação/genética , Pancreatectomia/métodos , Fenótipo , Somatostatina/análise , Resultado do Tratamento , Diazóxido/uso terapêutico , GenótipoRESUMO
AIMS: Neonatal diabetes mellitus (NDM) is a rare monogenic disorder, reported to affect less than 2 cases per 100,000 infants. There are two types, permanent (PNDM) and transient (TNDM). We describe our clinical experience in determining and comparing the genetic basis of diabetes in children with onset before 6months versus those diagnosed between 6 and 12months of age. METHODS: We reviewed medical records of children with diabetes diagnosed before 12months of age. Genetic testing was performed in all cases. RESULTS: 12 patients were diagnosed with diabetes before 6months of age (PNDM=6; TNDM=6), and 11 patients between 6 and 12months (all with permanent diabetes). Among children with PNDM, we identified three different KCNJ11 mutations in 5 patients, and one novel ABCC8 mutation in a single patient. Among children with TNDM, we detected a KCNJ11 and ABCC8 mutation each in a single patient and methylation abnormalities at chromosome 6q24 in 4 patients. Among children with diabetes diagnosed between 6 and 12months, 1 patient had an INS mutation and one patient was homozygous for an SLC19A2 mutation which confirmed a diagnosis of thiamine-responsive megaloblastic anaemia syndrome. Five of the patients with an ABCC8 or KCNJ11 mutation have successfully transferred from insulin to glibenclamide whist 1 child demonstrated a partial response to sulfonylurea treatment. CONCLUSIONS: Investigating the underlying genetic basis of diabetes in children with onset before 1year is useful for choosing the most efficient treatment, the basis of Personalized Medicine.
Assuntos
Diabetes Mellitus/tratamento farmacológico , Hipoglicemiantes/administração & dosagem , Doenças do Recém-Nascido/tratamento farmacológico , Insulina/administração & dosagem , Administração Oral , Diabetes Mellitus/genética , Feminino , Testes Genéticos , Humanos , Lactente , Recém-Nascido , Doenças do Recém-Nascido/genética , Insulina/genética , Masculino , Mutação/genética , Canais de Potássio Corretores do Fluxo de Internalização/genética , Compostos de Sulfonilureia/administração & dosagem , Receptores de Sulfonilureias/genéticaRESUMO
Diabetes mellitus is a public health problem, which affects a millions worldwide. Most diabetes cases are classified as type 2 diabetes mellitus, which is highly associated with obesity. Type 2 diabetes is considered a multifactorial disorder, with both environmental and genetic factors contributing to its development. An important issue linked with diabetes development is the failure of the insulin releasing mechanism involving abnormal activity of the ATP-dependent potassium channel, KATP. This channel is a transmembrane protein encoded by the KCNJ11 and ABCC8 genes. Furthermore, polymorphisms in these genes have been linked to type 2 diabetes because of the role of KATP in insulin release. While several genetic variations have been reported to be associated with this disease, the E23K polymorphism is most commonly associated with this pathology, as well as to obesity. Here, we review the molecular genetics of the potassium channel and discusses its most described polymorphisms and their associations with type 2 diabetes mellitus.
Assuntos
Trifosfato de Adenosina/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Canais de Potássio/metabolismo , Animais , Diabetes Mellitus Tipo 2/genética , Predisposição Genética para Doença/genética , Humanos , Polimorfismo Genético/genética , Canais de Potássio/genética , Canais de Potássio Corretores do Fluxo de Internalização/genética , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Receptores de Sulfonilureias/genética , Receptores de Sulfonilureias/metabolismoRESUMO
Thyrotoxicosis is the most common cause of the acquired flaccid muscle paralysis in adults called thyrotoxic periodic paralysis (TPP) and is characterised by transient hypokalaemia and hypophosphataemia under high thyroid hormone levels that is frequently precipitated by carbohydrate load. The sulphonylurea receptor 1 (SUR1 (ABCC8)) is an essential regulatory subunit of the ß-cell ATP-sensitive K(+) channel that controls insulin secretion after feeding. Additionally, the SUR1 Ala1369Ser variant appears to be associated with insulin sensitivity. We examined the ABCC8 gene at the single nucleotide level using PCR-restriction fragment length polymorphism (RFLP) analysis to determine its allelic variant frequency and calculated the frequency of the Ala1369Ser C-allele variant in a cohort of 36 Brazilian TPP patients in comparison with 32 controls presenting with thyrotoxicosis without paralysis (TWP). We verified that the frequency of the alanine 1369 C-allele was significantly higher in TPP patients than in TWP patients (61.1 vs 34.4%, odds ratio (OR)=3.42, P=0.039) and was significantly more common than the minor allele frequency observed in the general population from the 1000 Genomes database (61.1 vs 29.0%, OR=4.87, P<0.005). Additionally, the C-allele frequency was similar between TWP patients and the general population (34.4 vs 29%, OR=1.42, P=0.325). We have demonstrated that SUR1 alanine 1369 variant is associated with allelic susceptibility to TPP. We suggest that the hyperinsulinaemia that is observed in TPP may be linked to the ATP-sensitive K(+)/SUR1 alanine variant and, therefore, contribute to the major feedforward precipitating factors in the pathophysiology of TPP.
Assuntos
Estudos de Associação Genética , Variação Genética , Resistência à Insulina/genética , Receptores de Sulfonilureias/genética , Tireotoxicose/genética , Adulto , Idoso , Alelos , Estudos de Casos e Controles , Frequência do Gene , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Tireotoxicose/diagnóstico , Adulto JovemRESUMO
KCNJ11 (potassium inwardly rectifying channel, subfamily J, member 11) and ABCC8 (ATP-binding cassette, subfamily C (CFTR/MRP), member 8) have been studied for association with type 2 diabetes in various ethnic populations with contradictory results. We performed a comprehensive meta-analysis for KCNJ11 rs5219, rs5210, rs5215, and ABCC8 rs757110 to evaluate the effect of these regions on genetic susceptibility for type 2 diabetes. Forty-one case-control association studies of KCNJ11 and ABCC8 polymorphisms with type 2 diabetes, including 61,879 subjects, were identified and used in our meta-analysis. Combined odds ratios (OR) of associations of this disease with the rs5219 T, rs5210 G, rs5215 G, and rs757110 G alleles were 1.15 [95% confidence interval (95%CI) = 1.10-1.21, P < 0.0001], 1.16 (95%CI = 1.08-1.24, P = 0.023), 1.08 (95%CI = 1.02-1.13, P = 0.006), and 1.12 (95%CI = 1.07-1.18, P < 0.0001), respectively. The effect of allele T of rs5219 was similar (OR = 1.16) in Europeans and Japanese. However, rs5219 was not associated with type 2 diabetes in the Chinese Han population. Our meta-analysis demonstrated that KCNJ11 and ABCC8 polymorphisms are associated with risk for type 2 diabetes in the global population. Comparative genomics and bioinformatics analyses revealed that rs5210 is located within a conserved 3'-UTR, and that allele A may abolish the binding site of hsa-miR-1910 that the risk allele G possesses.
Assuntos
Diabetes Mellitus Tipo 2/genética , Estudos de Associação Genética , Canais de Potássio Corretores do Fluxo de Internalização/genética , Receptores de Sulfonilureias/genética , Alelos , Diabetes Mellitus Tipo 2/patologia , Etnicidade/genética , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Polimorfismo Genético , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Hydrogen sulphide (H(2) S) has been proposed as the third gasotransmitter. In animal cells, H(2) S has been implicated in several physiological processes. H(2) S is endogenously synthesized in both animals and plants by enzymes with l-Cys desulphydrase activity in the conversion of l-Cys to H(2) S, pyruvate and ammonia. The participation of H(2) S in both stomatal movement regulation and abscisic acid (ABA)-dependent induction of stomatal closure was studied in epidermal strips of three plant species (Vicia faba, Arabidopsis thaliana and Impatiens walleriana). The effect of H(2) S on stomatal movement was contrasted with leaf relative water content (RWC) measurements of whole plants subjected to water stress. In this work we report that exogenous H(2) S induces stomatal closure and this effect is impaired by the ATP-binding cassette (ABC) transporter inhibitor glibenclamide; scavenging H(2) S or inhibition of the enzyme responsible for endogenous H(2) S synthesis partially blocks ABA-dependent stomatal closure; and H(2) S treatment increases RWC and protects plants against drought stress. Our results indicate that H(2) S induces stomatal closure and participates in ABA-dependent signalling, possibly through the regulation of ABC transporters in guard cells.