Acid Lipase Deficiency and Lipid Storage in Wolman\u27s Disease and E600-Treated Cells in Culture

Fibroblasts obtained from a child with Wolman’s disease and maintained in culture demonstrated acid lipase deficiency, reached senescence prematurely and exhibited an abnormal #5 chromosome. When cytogenetic analysis was repeated on frozen and stored cells, the chromosomal defect could no longer be demonstrated, but other anomalies were present. The karyotypes of other Wolman’s disease cell cultures and the parents of the proband were normal. The mother’s fibroblasts had reduced acid lipase activity, consistent with a carrier-state, but the father’s fibroblasts had normal acid lipase activity. It was possible to classify a culture as Wolman’s disease, carrier or normal by the ability of medium from the culture to reduce the lipid stored in a Wolman’s disease cell culture. The culture of the proband stored more lipid than other Wolman’s disease cultures. Two enzymes present in fetal calf serum possessing paraoxonase activity could be differentiated by their sensitivity to heating at 56°C. The esterase inhibitor E600 was slightly more toxic to Wolman’s disease than to normal cells, and was also toxic to E. coli. Normal cells exhibited lipid storage when treated with 10(-4)M E600, but a more pronounced time-dependent accumulation of lipid occurred at 10(-3)M E600. p-Nitrophenol, the major metabolite of E600, had little effect on lipid storage. The amount of lipid stored varied directly with the serum concentration and was unaffected by heat inactivation of the serum. Histochemical stains and biochemical analyses were performed on cultured fibroblasts. Both Wolman’s disease and E600-treated cells showed storage of triglycerides and cholesteryl esters, although one Wolman’s disease culture had a normal level of triglyceride. The E600-treated cells also showed a large increase in phospholipid and small increases in free cholesterol and free fatty acid. Wolman’s disease cells treated with E600 showed increases comparable to the normal E600-treated cells, but no increase of free fatty acid was seen. Wolman’s disease heterozygotes appeared to have normal amounts of lipid. Lipid in Wolman’s disease and E600-treated cells fluoresced in ultraviolet light. Cholesteryl esters of untreated normal cells had more stearic (18:0) than oleic (18:1ω9) acid, whereas cholesteryl esters in Wolman’s disease, E600-treated cells, and fetal calf serum had three times more oleic than stearic acid, suggesting that serum lipid was taken up, but not degraded, in Wolman’s disease and E600-treated cells. Three Wolman’s disease cell cultures exhibited genetic deficiency of acid lipase. Normal fibroblasts had acid lipase activity, but possessed little neutral lipase activity. Acid lipase activity of normal cells was inhibited by E600. Wolman’s disease cells resembled normal cells by scanning electron microscopy. Except in a perinuclear zone which also had not stained with oil red O or neutral red, the cytoplasm of E600-treated cells had numerous bumps which appeared to form ridges along the path of actin stress filaments. Normal cells treated with free fatty acid or cholesterol, and Wolman’s disease cells treated with free fatty acid, exhibited lipid storage in large, peripheral lipid droplets. Lipid was generally stored in smaller granules closer to the nucleus in E600-treated and Wolman’s disease cells. E600-treated cells showed increased numbers of lysosomes by neutral red staining and had increased numbers of dense bodies ultrastructurally. The dense bodies of Wolman’s disease and E600-treated cells sometimes contained lipid clefts which probably consisted of cholesteryl ester. The dense bodies accumulated colloidal gold, suggesting their identity with secondary lysosomes. Although some differences were observed, E600-treated cells resembled Wolman’s disease cells histochemically, biochemically, and ultrastructurally

MliR, a novel MerR-like regulator of iron homeostasis, impacts metabolism, membrane remodeling, and cell adhesion in the marine Bacteroidetes Bizionia argentinensis

The MerR family is a group of transcriptional activators with conserved N-terminal helix-turn-helix DNA binding domains and variable C-terminal effector binding regions. In most MerR proteins the effector binding domain (EBD) contains a cysteine center suited for metal binding and mediates the response to environmental stimuli, such as oxidative stress, heavy metals or antibiotics. We here present a novel transcriptional regulator classified in the MerR superfamily that lacks an EBD domain and has neither conserved metal binding sites nor cysteine residues. This regulator from the psychrotolerant bacteria Bizionia argentinensis JUB59 is involved in iron homeostasis and was named MliR (MerR-like iron responsive Regulator). In silico analysis revealed that homologs of the MliR protein are widely distributed among different bacterial species. Deletion of the mliR gene led to decreased cell growth, increased cell adhesion and filamentation. Genome-wide transcriptomic analysis showed that genes associated with iron homeostasis were downregulated in mliR-deletion mutant. Through nuclear magnetic resonance-based metabolomics, ICP-MS, fluorescence microscopy and biochemical analysis we evaluated metabolic and phenotypic changes associated with mliR deletion. This work provides the first evidence of a MerR-family regulator involved in iron homeostasis and contributes to expanding our current knowledge on relevant metabolic pathways and cell remodeling mechanisms underlying in the adaptive response to iron availability in bacteria.Fil: Pellizza Pena, Leonardo Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Bialer, Magali Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Sieira, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Aran, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

Rapid progression and mortality of lysosomal acid lipase deficiency presenting in infants

PurposeThe purpose of this study was to enhance understanding of lysosomal acid lipase deficiency (LALD) in infancy.MethodsInvestigators reviewed medical records of infants with LALD and summarized data for the overall population and for patients with and without early growth failure (GF). Kaplan-Meier survival analyses were conducted for the overall population and for treated and untreated patients.ResultsRecords for 35 patients, 26 with early GF, were analyzed. Prominent symptom manifestations included vomiting, diarrhea, and steatorrhea. Median age at death was 3.7 months; estimated probability of survival past age 12 months was 0.114 (95% confidence interval (CI): 0.009-0.220). Among patients with early GF, median age at death was 3.5 months; estimated probability of survival past age 12 months was 0.038 (95% CI: 0.000-0.112). Treated patients (hematopoietic stem cell transplant (HSCT), n = 9; HSCT and liver transplant, n = 1) in the overall population and the early GF subset survived longer than untreated patients, but survival was still poor (median age at death, 8.6 months).ConclusionsThese data confirm and expand earlier insights on the progression and course of LALD presenting in infancy. Despite variations in the nature, onset, and severity of clinical manifestations, and treatment attempts, clinical outcome was poor.Genet Med 18 5, 452-458

High incidence of Noonan syndrome features including short stature and pulmonic stenosis in patients carrying NF1 missense mutations affecting p.Arg1809: genotype-phenotype correlation

Neurofibromatosis type 1 (NF1) is one of the most frequent genetic disorders, affecting 1:3,000 worldwide. Identification of genotype-phenotype correlations is challenging because of the wide range clinical variability, the progressive nature of the disorder, and extreme diversity of the mutational spectrum. We report 136 individuals with a distinct phenotype carrying one of five different NF1 missense mutations affecting p.Arg1809. Patients presented with multiple cafe-au-lait macules (CALM) with or without freckling and Lisch nodules, but no externally visible plexiform neurofibromas or clear cutaneous neurofibromas were found. About 25% of the individuals had Noonan-like features. Pulmonic stenosis and short stature were significantly more prevalent compared with classic cohorts (P<0.0001). Developmental delays and/or learning disabilities were reported in over 50% of patients. Melanocytes cultured from a CALM in a segmental NF1-patient showed two different somatic NF1 mutations, p.Arg1809Cys and a multi-exon deletion, providing genetic evidence that p.Arg1809Cys is a loss-of-function mutation in the melanocytes and causes a pigmentary phenotype. Constitutional missense mutations at p.Arg1809 affect 1.23% of unrelated NF1 probands in the UAB cohort, therefore this specific NF1 genotype-phenotype correlation will affect counseling and management of a significant number of patients

High Incidence of Noonan Syndrome Features Including Short Stature and Pulmonic Stenosis in Patients carrying NF1 Missense Mutations Affecting p.Arg1809: Genotype-Phenotype Correlation: HUMAN MUTATION

Neurofibromatosis type 1 (NF1) is one of the most frequent genetic disorders, affecting 1:3,000 worldwide. Identification of genotype–phenotype correlations is challenging because of the wide range clinical variability, the progressive nature of the disorder, and extreme diversity of the mutational spectrum. We report 136 individuals with a distinct phenotype carrying one of five different NF1 missense mutations affecting p.Arg1809. Patients presented with multiple café‐au‐lait macules (CALM) with or without freckling and Lisch nodules, but no externally visible plexiform neurofibromas or clear cutaneous neurofibromas were found. About 25% of the individuals had Noonan‐like features. Pulmonic stenosis and short stature were significantly more prevalent compared with classic cohorts (P < 0.0001). Developmental delays and/or learning disabilities were reported in over 50% of patients. Melanocytes cultured from a CALM in a segmental NF1‐patient showed two different somatic NF1 mutations, p.Arg1809Cys and a multi‐exon deletion, providing genetic evidence that p.Arg1809Cys is a loss‐of‐function mutation in the melanocytes and causes a pigmentary phenotype. Constitutional missense mutations at p.Arg1809 affect 1.23% of unrelated NF1 probands in the UAB cohort, therefore this specific NF1 genotype–phenotype correlation will affect counseling and management of a significant number of patients

Gain and loss of TASK3 channel function and its regulation by novel variation cause KCNK9 imprinting syndrome

Background: Genomics enables individualized diagnosis and treatment, but large challenges remain to functionally interpret rare variants. To date, only one causative variant has been described for KCNK9 imprinting syndrome (KIS). The genotypic and phenotypic spectrum of KIS has yet to be described and the precise mechanism of disease fully understood. Methods: This study discovers mechanisms underlying KCNK9 imprinting syndrome (KIS) by describing 15 novel KCNK9 alterations from 47 KIS-affected individuals. We use clinical genetics and computer-assisted facial phenotyping to describe the phenotypic spectrum of KIS. We then interrogate the functional effects of the variants in the encoded TASK3 channel using sequence-based analysis, 3D molecular mechanic and dynamic protein modeling, and in vitro electrophysiological and functional methodologies. Results: We describe the broader genetic and phenotypic variability for KIS in a cohort of individuals identifying an additional mutational hotspot at p.Arg131 and demonstrating the common features of this neurodevelopmental disorder to include motor and speech delay, intellectual disability, early feeding difficulties, muscular hypotonia, behavioral abnormalities, and dysmorphic features. The computational protein modeling and in vitro electrophysiological studies discover variability of the impact of KCNK9 variants on TASK3 channel function identifying variants causing gain and others causing loss of conductance. The most consistent functional impact of KCNK9 genetic variants, however, was altered channel regulation. Conclusions: This study extends our understanding of KIS mechanisms demonstrating its complex etiology including gain and loss of channel function and consistent loss of channel regulation. These data are rapidly applicable to diagnostic strategies, as KIS is not identifiable from clinical features alone and thus should be molecularly diagnosed. Furthermore, our data suggests unique therapeutic strategies may be needed to address the specific functional consequences of KCNK9 variation on channel function and regulation