Deficiencia del transportador de glucosa tipo 1: aspectos clínicos, diagnóstico y terapéutica / Glucose transporter type 1 deficiency syndrome: clinical aspects, diagnosis, and treatment

El síndrome de deficiencia del transportador de glucosa tipo 1 es una enfermedad de causa genética, que involucra el gen SLC2A1. En general, se presenta durante los primeros años de vida con retraso en la adquisición de pautas madurativas, epilepsia farmacorresistente y desórdenes del movimiento. La clínica y la disminución de glucosa en líquido cefalorraquídeo permiten sospechar el diagnóstico, el cual debe ser confirmado mediante el estudio molecular del gen SLC2A1. Debido a que se trata de una enfermedad poco frecuente y de expresión clínica variable, el diagnóstico precoz suele representar un desafío para los equipos de salud. Este es importante, ya que la implementación de la terapia cetogénica logra controlar las manifestaciones clínicas y mejora el pronóstico a largo plazo. Presentamos una revisión sobre el déficit del transportador de glucosa tipo 1, que abarca sus características clínicas, bioquímicas, moleculares y terapéuticas.

Glucose transporter type 1 deficiency with a typical onset is a genetic disorder associated with the SLC2A1 gene. Usually appears during the first years of life with severe developmental delay, drugresistant epilepsy, and movement disorders. Diagnosis is suspected based on clinical manifestations and a low glucose level in cerebrospinal fluid, and should be confirmed by the molecular genetic study of the SLC2A1 gene. As it is a rare disease with variable clinical expression, early diagnosis is often challenging for the healthcare team. Nevertheless, this is important because early implementation of ketogenic therapy will lead to control of the clinical manifestations and a better long-term prognosis. Here we review the glucose transporter type 1 deficiency syndrome focusing on its clinical, biochemical, molecular, and therapeutic characteristics.

Hemidistonía y hemicorea en un paciente pediátrico con déficit del transportador de glucosa de tipo 1 / Hemidystonia and hemichorea in a pediatric patient with glucose transporter type 1 deficiency

El síndrome de deficiencia del transportador de glucosa cerebral de tipo 1 es una enfermedad neurometabólica rara en pediatría. Existe un fenotípico clásico (85 %) y otro no clásico (15 %). Ambos fenotipos se asocian con hipoglucorraquia. Se identifican múltiples mutaciones en el gen SLC2A1. El tratamiento es la terapia cetogénica. Se presenta un varón que comenzó a los cuatro años con hemicorea y hemidistonía medicado con anticonvulsivantes sin respuesta clínica, por lo que consultó nuevamente a los seis años. Con sospecha diagnóstica de síndrome de déficit de glut-1 atípico se realizó punción lumbar; el diagnóstico se confirmó por la presencia de hipoglucorraquia. Inmediatamente después de iniciar la dieta cetogénica, el paciente no presentó más movimientos anormales durante los siguientes 8 años hasta la actualidad, ya cumplidos los 14 años.

Glucose transporter type 1 deficiency syndrome is a rare pediatric neurometabolic disorder. There are two phenotypes: the classical phenotype (85%) and the non-classic (15%). Both phenotypes are associated with hypoglycorrhachia. Multiple mutations are described in the SCL2A1 gene. The treatment is the ketogenic diet. We report a case of a four-year-old male patient who started with hemichorea and hemidystonia and was medicated with drugs for seizures without clinical response, that's why his parents made another pediatric consultation at his six-year-old. With the suggestive clinical findings of glucose transporter type 1 deficiency syndrome the lumbar puncture was made confirming the diagnosis. Immediately after starting the ketogenic diet the patient stopped making abnormal movements up to the moment when he is fourteen years old, eight years after.

Analysis of SLC35A2 gene variant in a child with congenital disorder of glycosylation type IIm / 中华医学遗传学杂志

OBJECTIVE@#To investigate the clinical features and SLC35A2 variant of a case of congenital disorder of glycosylation type IIm (CDG-IIm), and to identify the possible causes of the disease.@*METHODS@#Trio-whole exome sequencing (WES) was used to analyze the gene variant of the children and their parents. The suspicious gene variants were screened for Sanger verification and the bioinformatics prediction was used to analyze the hazard of variant.@*RESULTS@#The clinical manifestations of the child were epilepsy, global growth retardation, nystagmus, myocarditis and other symptoms. MRI showed brain dysplasia such as wide frontal temporal sulcus and subarachnoid space on both sides. Echocardiography showed left ventricular wall thickening and patent foramen ovale. According to the results of gene detection, there was a heterozygous missense variant c.335C>A (p.Thr112Lys) in SLC35A2 gene. The parents were wild-type at this locus, which was a de novo variant. At the same time, there was no report of this variant in the relevant literature, which was a novel variant in SLC35A2 gene. According to the genetic variant guidelines of American College of Medical Genetics and Genomics, SLC35A2 gene c.335C>A (p.Thr112Lys) variant was predicted to be likely pathogenic (PS2+PM2+PP3).@*CONCLUSION@#The variant of SLC35A2 gene c.335C>A(p.Thr112Lys) may be the cause of the disease in the child.

Effect of Salmonella typhimurium toxin on the expression of rabbit intestinal functions.

BACKGROUND & OBJECTIVES: Infection by Salmonella Typhimurium is one of the leading causes of intestinal dysfunction, however the underlying mechanism of this effect is largely unknown. Hence the effect of enterotoxin secreted by Salmonella Typhimurium-(S-LT) was studied on D-glucose absorption and brush border enzymes in rabbit ileum. mRNA levels encoding these proteins were also analysed. METHODS: Adult male New Zealand white rabbits were used. The polymyxine B extract of enterotoxin obtained from Salmonella Typhimurium was tested for the presence of enterotoxicity by rabbit ileal loop test. D-glucose uptake by ileal tissue was measured by the tissue accumulation method. Intestinal brush border membranes were isolated and the effect of S-LT on various brush border enzymes studied. RESULTS: S-LT significantly inhibited (P < 0.01) the absorption of Na+ dependent D-glucose uptake but had no effect on Na+ independent sugar uptake in rabbit ileum. The activities of brush border sucrase (72% P < 0.001) and lactase (47% P < 0.01) and alkaline phosphatase (43% P < 0.01) were also significantly reduced in infected animals as compared to the controls. Northern blot analysis revealed that mRNA levels encoding Na+ glucose co-transporter (SGLT1), brush border lactase and sucrase activities were unaffected in Salmonella infected rabbit ileal loops. INTERPRETATION & CONCLUSION: The findings suggest that the intestinal dysfunctions observed in Salmonella infection are unrelated to mRNA expression encoding Na+ glucose co-transporter and brush border enzyme proteins in rabbit ileum.

C/EBP binding activity to site F of the rat GLUT2 glucose transporter gene promoter is attenuated by c-Jun in vitro

The expression of the GLUT2 glucose transporter gene in liver is suppressed in cultured hepatoma cell lines and primary cultured hepatocytes. Earlier report showed that CCAAT/enhancer binding protein (C/EBP) regulates the promoter activity of the rat GLUT2 glucose transporter gene in liver cells. C/EBPa and C/EBPb activated the promoter activity by binding to at least two regions of the promoter and one of the C/EBP binding sites, named as site F, also has the AP-1 binding consensus. In this study, we investigated whether the AP-1 can influence on C/EBP binding to this site. The addition of recombinant c-Jun protein with liver extract caused the attenuation of C/EBP binding to site F with the appearance of a new shifted band. The shifted band was competed out with the addition of unlabeled AP-1 consensus oligonucleotide, indicating that c-Jun also can bind to site F. Another C/EBP site on GLUT2 promoter, site H, did not bind AP-1. Analysis of the DNA-protein complex revealed that C/EBP and c-Jun bind to site F in mutually exclusive manner rather than form heterodimeric complex with each other. From these results, it is suggested that the transcriptional activation of C/EBP may be influenced by c-Jun protein in certain status of the liver cells, such as acute phase response, as well as hepatocarcinogenesis.

A mechanism of differential expression of GLUT2 in hepatocyte and pancreatic beta-cell line

DNase I footprinting assay using liver nuclear extracts revealed six protected regions between nucleotide -600 and +110 and hence named Box I-VI. Upstream promoter element (UPE), a DNA element playing crucial role in transcriptional control of the tissue specific expression of pancreatic beta-cell, has been detected within the proximal region of rat GLUT2 promoter. This region is included in Box VI. The protein-DNA interaction in this region (Box VI) was confirmed by mobility shift assay using liver nuclear extracts. Deletion of the region between -585 bp and -146 bp resulted in dramatic changes in promoter activity when they were expressed in liver and beta-cell derived cell line. When -585/-146 construct was expressed in liver, the activity was decreased to 46%, whereas the activity in beta-cell line, HIT-T15 cell, was increased by 84% when compared to -146/+190 construct. These opposing phenomena can be explained by the fact that beta-cell specifically expresses the UPE binding protein. Assuming that there may be Box VI-binding protein playing negative roles both in hepatocyte and beta-cell, and that the protein acts as a negative regulator of GLUT2 gene, the UPE binding protein in the beta-cell may overcome the inhibition by binding to the protein.

Antisense GLUT1 RNA suppresses the transforming phenotypes of NIH 3T3 cells transformed by N-Ras

An antisense approach was attempted to investigate the role of antisense GLUT1 RNA in suppressing tumor cell phenotypes using N-ras-transformed NIH 3T3 cells. The established cell line transformed by ras showed typical biological characteristics of cancer cells, such as increased glucose transport, GLUT1 mRNA contents, and the ability to form colonies on the soft agar. In this system, the plasmids (pMAM-GLUT1(rev)) which can transcribe the antisense GLUT1 RNA were transfected and the accompanying changes in the phenotypes of the ras-transformed cells were observed. The expression of antisense GLUT1 RNA by induction with dexamethasone reduced the glucose transport by 30% (1.97 +/- 0.13 nmoles) after 4 min incubation when compared to the non-induction group of transformed cell (2.85 +/- 0.19 nmoles). Also, the number of colonies sized over 50 microns on the soft agar was reduced significantly in the antisense RNA expressing group compared to non-induction group. These results suggest that the expression of antisense GLUT1 RNA reduced the glucose transport and transforming potential in soft agar possibly by hybridization with GLUT1 mRNA in N-ras-transformed NIH 3T3 cells.

Cloning and expression of rat liver type glucose transporter and translocation by insulin in Chinese hamster ovary cells

The 5'- and 3'-side half of liver type glucose transporter (GLUT2) cDNA was amplified from total RNA or mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR). The amplified 5'-side fragment of GLUT2 cDNA was inserted into pGEM4Z and named pGLGT1, and the 3'-side fragment of GLUT2 cDNA was inserted into the HindIII site of pGLGT1 to construct pGLGT2 which contains an entire open reading frame of GLUT2 cDNA. The GLUT2 cDNA in pGLGT2 was transferred to an eukaryotic expression vector (pMAM) to construct pMLGT, which was expressed in the insulin-sensitive Chinese hamster ovary (CHO) cells. Western blot analysis showed that the GLUT2 gene in pMLGT was expressed in the transfected CHO cells successfully. The GLUT2 content in the plasma membrane fraction of insulin-treated CHO cells expressing GLUT2 increased 3.8-fold compared to that of the control group. This result suggests that GLUT2, which is not subjected to translocation by insulin in the cells of its major distribution, can be translocated if it is expressed in the suitable cells sensitive to insulin action.