- Primary aldosteronism associated with a germline variant in CACNA1H. [Journal Article]
- BCBMJ Case Rep 2019 May 23; 12(5)
- The CACNA1H gene encodes the pore-forming α1 subunit of the T-type voltage-dependent calcium channel CaV3.2, expressed abundantly in the adrenal cortex. Mutations in CACNA1H are associated with vario…
The CACNA1H gene encodes the pore-forming α1 subunit of the T-type voltage-dependent calcium channel CaV3.2, expressed abundantly in the adrenal cortex. Mutations in CACNA1H are associated with various forms of primary aldosteronism (PA), including familial hyperaldosteronism type 4 (FH4). We describe a patient with refractory hypokalaemia and elevated aldosterone secretion independent of renin activity. Despite the absence of overt hypertension in this patient, the laboratory evaluation was consistent with a diagnosis of PA. Whole-exome sequencing revealed a de novo missense variant, R890H, in the voltage sensing domain of CACNA1H Expression of the variant channel in cells resulted in decreased whole-cell current, consistent with a loss-of-function. We hypothesise this variant is the genetic cause of pathological aldosterone secretion in this patient, and thereby expand the current understanding of the genetic basis of FH4.
- How Charge and Triple Size-Selective Membrane Separation of Peptides from Salmon Protein Hydrolysate Orientate their Biological Response on Glucose Uptake. [Journal Article]
- IJInt J Mol Sci 2019 Apr 20; 20(8)
- The valorization of by-products from natural organic sources is an international priority to respond to environmental and economic challenges. In this context, electrodialysis with filtration membran…
The valorization of by-products from natural organic sources is an international priority to respond to environmental and economic challenges. In this context, electrodialysis with filtration membrane (EDFM), a green and ultra-selective process, was used to separate peptides from salmon frame protein hydrolysate. For the first time, the simultaneous separation of peptides by three ultrafiltration membranes of different molecular-weight exclusion limits (50, 20, and 5 kDa) stacked in an electrodialysis system, allowed for the generation of specific cationic and anionic fractions with different molecular weight profiles and bioactivity responses. Significant decreases in peptide recovery, yield, and molecular weight (MW) range were observed in the recovery compartments depending on whether peptides had to cross one, two, or three ultrafiltration membranes. Moreover, the Cationic Recovery Compartment 1 fraction demonstrated the highest increase (42%) in glucose uptake on L6 muscle cells. While, in the anionic configuration, both Anionic Recovery Compartment 2 and Anionic Recovery Compartment 3 fractions presented a glucose uptake response in basal condition similar to the insulin control. Furthermore, Cationic Recovery Compartment 3 was found to contain inhibitory peptides. Finally, LC-MS analyses of the bioassay-guided bioactive fractions allowed us to identify 11 peptides from salmon by-products that are potentially responsible for the glucose uptake improvement.
- StatPearls: Biochemistry, Tetrahydrofolate [BOOK]
- BOOKStatPearls Publishing: Treasure Island (FL)
- Tetrahydrofolate or tetrahydrofolic acid is a folic acid derivative that serves as a coenzyme for metabolic reactions involving amino acids and nucleic acids. The term "folate" denoted a water-solubl…
Tetrahydrofolate or tetrahydrofolic acid is a folic acid derivative that serves as a coenzyme for metabolic reactions involving amino acids and nucleic acids. The term "folate" denoted a water-soluble B-complex vitamin that functions in the transfer process of single-carbon groups at different stages of oxidation and essential for biosynthesis of certain amino acid, purine bases and thymine which is a type of pyrimidine base. Chemically folic acid contains three components: PABA(para amino benzoic acid, pteridine ring and glutamic acid. Folic acid usually contains one glutamic residue which is known as PGA( pteroyl-glutamic acid). The active form of folic acid is called as tetrahydrofolic acid or more popularly known as tetrahydrofolate(THF or FH4). In presence of 2 mole of NADPH and with the help of an enzyme known as dihydrofolate reductase folic acid is converted to tetrahydrofolate. Hydrogen atoms are added in positions 5,6,7 and 8 of folic acid to converted it into tetrehydrofolic acid. This reducing equivalent used to provide by two moles of NADPH.
- The crystal structure of a tetrahydrofolate-bound dihydrofolate reductase reveals the origin of slow product release. [Journal Article]
- CBCommun Biol 2018; 1:226
- Dihydrofolate reductase (DHFR) catalyzes the stereospecific reduction of 7,8-dihydrofolate (FH2) to (6s)-5,6,7,8-tetrahydrofolate (FH4) via hydride transfer from NADPH. The consensus Escherichia coli…
Dihydrofolate reductase (DHFR) catalyzes the stereospecific reduction of 7,8-dihydrofolate (FH2) to (6s)-5,6,7,8-tetrahydrofolate (FH4) via hydride transfer from NADPH. The consensus Escherichia coli DHFR mechanism involves conformational changes between closed and occluded states occurring during the rate-limiting product release step. Although the Protein Data Bank (PDB) contains over 250 DHFR structures, the FH4 complex structure responsible for rate-limiting product release is unknown. We report to our knowledge the first crystal structure of an E. coli. DHFR:FH4 complex at 1.03 Å resolution showing distinct stabilizing interactions absent in FH2 or related (6R)-5,10-dideaza-FH4 complexes. We discover the time course of decay of the co-purified endogenous FH4 during crystal growth, with conversion from FH4 to FH2 occurring in 2-3 days. We also determine another occluded complex structure of E. coli DHFR with a slow-onset nanomolar inhibitor that contrasts with the methotrexate complex, suggesting a plausible strategy for designing DHFR antibiotics by targeting FH4 product conformations.
- Low-dose methotrexate enhances cycling of highly anaplastic cancer cells. [Journal Article]
- CCCell Cycle 2017; 16(3):280-285
- We previously showed that cellular RedOx state governs the G1-S transition of AH130 hepatoma, a tumor spontaneously reprogrammed to the embryonic stem cell stage. This transition is impaired when the…
We previously showed that cellular RedOx state governs the G1-S transition of AH130 hepatoma, a tumor spontaneously reprogrammed to the embryonic stem cell stage. This transition is impaired when the mithocondrial electron transport system is blocked by specific inhibitors (antimycin A) or the respiratory chain is saturated by adding to the cells high concentrations of pyruvate. The antimycin A or pyruvate block is removed by the addition of adequate concentrations of folate (F). This suggests that the G1-S transition of AH130 cells depends on a respiration-linked step of DNA synthesis related to folate metabolism. In the study reported here, we characterized the effects of methotrexate (MTX), an inhibitor of dihydofolate-reductase, on the G1-S transition of hepatoma cells, in the absence or the presence of exogenously added F, dihydrofolate (FH2) or tetrahydrofolate (FH4). MTX, at 1 μM or higher concentrations, inhibited G1-S transition. This inhibition was completely removed by exogenous folates. Surprisingly, 10 nM MTX stimulated G1-S transition. The addition of F, but not FH2 or FH4, significantly increased this effect. Furthermore, 10 nM MTX removed the block of the G1-S transition operated by antimycin A or pyruvate, an effect which was enhanced in the presence of F. Finally, the stimulatory effect of 10 nM MTX was inhibited in the presence of serine. Our findings indicated that, under certain conditions, MTX may stimulate, rather than inhibiting, the cycling of cancer cells exhibiting a stem cell-like phenotype, such as AH130 cells. This may impact the therapeutic use of MTX and of folates as supportive care.
- Examination of the Feynman-Hibbs Approach in the Study of NeN-Coronene Clusters at Low Temperatures. [Journal Article]
- JPJ Phys Chem A 2016 Jul 14; 120(27):5370-9
- Feynman-Hibbs (FH) effective potentials constitute an appealing approach for investigations of many-body systems at thermal equilibrium since they allow us to easily include quantum corrections withi…
Feynman-Hibbs (FH) effective potentials constitute an appealing approach for investigations of many-body systems at thermal equilibrium since they allow us to easily include quantum corrections within standard classical simulations. In this work we apply the FH formulation to the study of NeN-coronene clusters (N = 1-4, 14) in the 2-14 K temperature range. Quadratic (FH2) and quartic (FH4) contributions to the effective potentials are built upon Ne-Ne and Ne-coronene analytical potentials. In particular, a new corrected expression for the FH4 effective potential is reported. FH2 and FH4 cluster energies and structures-obtained from energy optimization through a basin-hopping algorithm as well as classical Monte Carlo simulations-are reported and compared with reference path integral Monte Carlo calculations. For temperatures T > 4 K, both FH2 and FH4 potentials are able to correct the purely classical calculations in a consistent way. However, the FH approach fails at lower temperatures, especially the quartic correction. It is thus crucial to assess the range of applicability of this formulation and, in particular, to apply the FH4 potentials with great caution. A simple model of N isotropic harmonic oscillators allows us to propose a means of estimating the cutoff temperature for the validity of the method, which is found to increase with the number of atoms adsorbed on the coronene molecule.
- Microarray Analyses Reveal Marked Differences in Growth Factor and Receptor Expression Between 8-Cell Human Embryos and Pluripotent Stem Cells. [Journal Article]
- SCStem Cells Dev 2016 Jan 15; 25(2):160-77
- Previous microarray analyses of RNAs from 8-cell (8C) human embryos revealed a lack of cell cycle checkpoints and overexpression of core circadian oscillators and cell cycle drivers relative to pluri…
Previous microarray analyses of RNAs from 8-cell (8C) human embryos revealed a lack of cell cycle checkpoints and overexpression of core circadian oscillators and cell cycle drivers relative to pluripotent human stem cells [human embryonic stem cells/induced pluripotent stem (hES/iPS)] and fibroblasts, suggesting growth factor independence during early cleavage stages. To explore this possibility, we queried our combined microarray database for expression of 487 growth factors and receptors. Fifty-one gene elements were overdetected on the 8C arrays relative to hES/iPS cells, including 14 detected at least 80-fold higher, which annotated to multiple pathways: six cytokine family (CSF1R, IL2RG, IL3RA, IL4, IL17B, IL23R), four transforming growth factor beta (TGFB) family (BMP6, BMP15, GDF9, ENG), one fibroblast growth factor (FGF) family [FGF14(FH4)], one epidermal growth factor member (GAB1), plus CD36, and CLEC10A. 8C-specific gene elements were enriched (73%) for reported circadian-controlled genes in mouse tissues. High-level detection of CSF1R, ENG, IL23R, and IL3RA specifically on the 8C arrays suggests the embryo plays an active role in blocking immune rejection and is poised for trophectoderm development; robust detection of NRG1, GAB1, -2, GRB7, and FGF14(FHF4) indicates novel roles in early development in addition to their known roles in later development. Forty-four gene elements were underdetected on the 8C arrays, including 11 at least 80-fold under the pluripotent cells: two cytokines (IFITM1, TNFRSF8), five TGFBs (BMP7, LEFTY1, LEFTY2, TDGF1, TDGF3), two FGFs (FGF2, FGF receptor 1), plus ING5, and WNT6. The microarray detection patterns suggest that hES/iPS cells exhibit suppressed circadian competence, underexpression of early differentiation markers, and more robust expression of generic pluripotency genes, in keeping with an artificial state of continual uncommitted cell division. In contrast, gene expression patterns of the 8C embryo suggest that it is an independent circadian rhythm-competent equivalence group poised to signal its environment, defend against maternal immune rejection, and begin the rapid commitment events of early embryogenesis.
- FH4=STAP1. Another gene for familial hypercholesterolemia? Relevance to cascade testing and drug development? [Editorial]
- CircRCirc Res 2014 Aug 29; 115(6):534-6
- Mutations in STAP1 are associated with autosomal dominant hypercholesterolemia. [Case Reports]
- CircRCirc Res 2014 Aug 29; 115(6):552-5
- CONCLUSIONS: We mapped a novel ADH locus at 4p13 and identified 4 variants in STAP1 that associate with ADH.
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- The rulB gene of plasmid pWW0 is a hotspot for the site-specific insertion of integron-like elements found in the chromosomes of environmental Pseudomonas fluorescens group bacteria. [Journal Article]
- EMEnviron Microbiol 2014; 16(8):2374-88
- The rulAB operon of Pseudomonas spp. confers fitness traits on the host and has been suggested to be a hotspot for insertion of mobile elements that carry avirulence genes. Here, for the first time, …
The rulAB operon of Pseudomonas spp. confers fitness traits on the host and has been suggested to be a hotspot for insertion of mobile elements that carry avirulence genes. Here, for the first time, we show that rulB on plasmid pWW0 is a hotspot for the active site-specific integration of related integron-like elements (ILEs) found in six environmental pseudomonads (strains FH1-FH6). Integration into rulB on pWW0 occurred at position 6488 generating a 3 bp direct repeat. ILEs from FH1 and FH5 were 9403 bp in length and contained eight open reading frames (ORFs), while the ILE from FH4 was 16 233 bp in length and contained 16 ORFs. In all three ILEs, the first 5.1 kb (containing ORFs 1-4) were structurally conserved and contained three predicted site-specific recombinases/integrases and a tetR homologue. Downstream of these resided ORFs of the 'variable side' with structural and sequence similarity to those encoding survival traits on the fitness enhancing plasmid pGRT1 (ILE(FH1) and ILE(FH5)) and the NR-II virulence region of genomic island PAGI-5 (ILE(FH4)). Collectively, these ILEs share features with the previously described type III protein secretion system effector ILEs and are considered important to host survival and transfer of fitness enhancing and (a)virulence genes between bacteria.