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1. The Association between Whole‐Brain MR Spectroscopy and IDH Mutation Status in Gliomas

   https://doi.org/10.1111/jon.12685  

   Goryawala, Mohammed ; Saraf‐Lavi, Efrat ; Nagornaya, Natalia ; Heros, Deborah ; Komotar, Ricardo ; Maudsley, Andrew A. ( December 2019 , Journal of Neuroimaging)

   Mutations in isocitrate dehydrogenase (IDH) have a direct effect on gliomagenesis. The purpose of this study is to quantify differences in brain metabolites due to IDH mutations.

   Magnetic Resonance Spectroscopic Imaging (MRSI) was performed in 35 patients with gliomas of different grade and varied IDH mutation status. Volumes of interest (VOIs) for active tumor (tVOI), peritumoral area (pVOI), and contralateral normal‐appearing white matter (cVOI) were created. Metabolite ratios of Choline (Cho) to bothN‐acetylaspartate (NAA) and Creatine (Cr) were estimated. Ratios of Glutamate/Glutamine complex (Glx) and myoinositol (mIno) to Cr were also quantified. General linear models (GLMs) were used to estimate the effects of IDH mutation on metabolite measures, with age, gender, and tumor grade used as covariates.

   GLM analysis showed that maximum Cho/NAA and Cho/Cr in the tVOI were significantly (P< .05) higher in IDH mutant lesions as compared to wild‐type. In the pVOI, mean Cho/Cr was found to be significantly different among IDH mutant and wild‐type gliomas. Mean Cho/NAA (P= .306) and Cho/Cr (P= .292) within the tVOI were not significantly different. Ratios of Glx/Cr and mIno/Cr in any region showed no significant differences between IDH mutant and wild‐type gliomas. No significant differences in metabolite ratios were seen in the cVOI between IDH mutants and wild‐types.

   IDH mutation's effect in gliomas show an increase in Cho in the tumor and perilesional regions as compared to wild‐type lesions but do not show widespread changes across the brain.

    

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2. Repurposing Iron‐ and 2‐Oxoglutarate‐Dependent Oxygenases to Catalyze Olefin Hydration

   https://doi.org/10.1002/anie.202311099  

   Wang, Bingnan ; Lu, Yong ; Cha, Lide ; Chen, Tzu‐Yu ; Palacios, Philip M. ; Li, Liping ; Guo, Yisong ; Chang, Wei‐chen ; Chen, Chuo ( September 2023 , Angewandte Chemie International Edition)

   Mononuclear nonheme iron(II) and 2‐oxoglutarate (Fe/2OG)‐dependent oxygenases and halogenases are known to catalyze a diverse set of oxidative reactions, including hydroxylation, halogenation, epoxidation, and desaturation in primary metabolism and natural product maturation. However, their use in abiotic transformations has mainly been limited to C−H oxidation. Herein, we show that various enzymes of this family, when reconstituted with Fe(II) or Fe(III), can catalyze Mukaiyama hydration—a redox neutral transformation. Distinct from the native reactions of the Fe/2OG enzymes, wherein oxygen atom transfer (OAT) catalyzed by an iron‐oxo species is involved, this nonnative transformation proceeds through a hydrogen atom transfer (HAT) pathway in a 2OG‐independent manner. Additionally, in contrast to conventional inorganic catalysts, wherein a dinuclear iron species is responsible for HAT, the Fe/2OG enzymes exploit a mononuclear iron center to support this reaction. Collectively, our work demonstrates that Fe/2OG enzymes have utility in catalysis beyond the current scope of catalytic oxidation.

    

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3. Repurposing Iron‐ and 2‐Oxoglutarate‐Dependent Oxygenases to Catalyze Olefin Hydration

   https://doi.org/10.1002/ange.202311099  

   Wang, Bingnan ; Lu, Yong ; Cha, Lide ; Chen, Tzu‐Yu ; Palacios, Philip M. ; Li, Liping ; Guo, Yisong ; Chang, Wei‐chen ; Chen, Chuo ( September 2023 , Angewandte Chemie)

   Mononuclear nonheme iron(II) and 2‐oxoglutarate (Fe/2OG)‐dependent oxygenases and halogenases are known to catalyze a diverse set of oxidative reactions, including hydroxylation, halogenation, epoxidation, and desaturation in primary metabolism and natural product maturation. However, their use in abiotic transformations has mainly been limited to C−H oxidation. Herein, we show that various enzymes of this family, when reconstituted with Fe(II) or Fe(III), can catalyze Mukaiyama hydration—a redox neutral transformation. Distinct from the native reactions of the Fe/2OG enzymes, wherein oxygen atom transfer (OAT) catalyzed by an iron‐oxo species is involved, this nonnative transformation proceeds through a hydrogen atom transfer (HAT) pathway in a 2OG‐independent manner. Additionally, in contrast to conventional inorganic catalysts, wherein a dinuclear iron species is responsible for HAT, the Fe/2OG enzymes exploit a mononuclear iron center to support this reaction. Collectively, our work demonstrates that Fe/2OG enzymes have utility in catalysis beyond the current scope of catalytic oxidation.

    

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4. Development of a relative quantification method for infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry imaging of Arabidopsis seedlings

   https://doi.org/10.1002/rcm.8616  

   Bagley, M. Caleb ; Stepanova, Anna N. ; Ekelöf, Måns ; Alonso, Jose M. ; Muddiman, David C. ( February 2020 , Rapid Communications in Mass Spectrometry)

   Mass spectrometry imaging of young seedlings is an invaluable tool in understanding how mutations affect metabolite accumulation in plant development. However, due to numerous biological considerations, established methods for the relative quantification of analytes using infrared matrix‐assisted laser desorption electrospray ionization (IR‐MALDESI) mass spectrometry imaging are not viable options. In this study, we report a method for the quantification of auxin‐related compounds using stable‐isotope‐labelled (SIL) indole‐3‐acetic acid (IAA) doped into agarose substrate.

   Wild‐typeArabidopsis thalianaseedlings,sur2andwei8 tar2loss‐of‐function mutants, andYUC1gain‐of‐function line were grown for 3 days in the dark in standard growth medium. SIL‐IAA was doped into a 1% low‐melting‐point agarose gel and seedlings were gently laid on top for IR‐MALDESI imaging with Orbitrap mass spectrometry analysis. Relative quantification was performed post‐acquisition by normalization of auxin‐related compounds to SIL‐IAA in the agarose. Amounts of auxin‐related compounds were compared between genotypes to distinguish the effects of the mutations on the accumulation of indolic metabolites of interest.

   IAA added to agarose was found to remain stable, with repeatability and abundance features of IAA comparable with those of other compounds used in other methods for relative quantification in IR‐MALDESI analyses. Indole‐3‐acetaldoxime was increased insur2mutants compared with wild‐type and other mutants. Other auxin‐related metabolites were either below the limits of quantification or successfully quantified but showing little difference among mutants.

   Agarose was shown to be an appropriate sampling surface for IR‐MALDESI mass spectrometry imaging ofArabidopsisseedlings. SIL‐IAA doping of agarose was demonstrated as a viable technique for relative quantification of metabolites in live seedlings or tissues with similar biological considerations.

    

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5. Reelin dorsal horn neurons co‐express Lmx1b and are mispositioned in disabled‐1 mutant mice

   https://doi.org/10.1111/ejn.14847  

   Yvone, Griselda M. ; Chavez‐Martinez, Carmine L. ; Nguyen, Amanda R. ; Wang, Deborah J. ; Phelps, Patricia E. ( August 2020 , European Journal of Neuroscience)

   Mice missing either Reelin or Disabled‐1 (Dab1) exhibit dorsal horn neuronal positioning errors and display heat hypersensitivity and mechanical insensitivity. Reelin binds its receptors, apolipoprotein E receptor 2 and very low‐density lipoprotein receptor, leading to the recruitment and phosphorylation of Dab1 and activation of downstream pathways that regulate neuronal migration. Previously, we reported that 70% of Dab1 laminae I–II neurons co‐expressed LIM‐homeobox transcription factor 1‐beta (Lmx1b). Here, we asked whether Reelin‐expressing dorsal horn neurons co‐express Lmx1b, are mispositioned indab1mutants, and contribute to nociceptive abnormalities. About 90% of Reelin‐labeled neurons are Lmx1b‐positive in laminae I–II, confirming that most Reelin and Dab1 neurons are glutamatergic. We determined that Reelin‐Lmx1b and Dab1‐Lmx1b dorsal horn neurons are separate populations, and together, comprise 37% of Lmx1b‐positive cells within and above the Isolectin B4 (IB4) layer in wild‐type mice. Compared to wild‐type mice,dab1mutants have a reduced area of laminae I–II outer (above the IB4 layer), more Reelin‐Lmx1b neurons within the IB4 layer, and fewer Reelin‐Lmx1b neurons within the lateral reticulated area of lamina V and lateral spinal nucleus. Interestingly, both Reelin‐ and Dab1‐labeled dorsal horn neurons sustain similar positioning errors in mutant mice. After noxious thermal and mechanical stimulation, Reelin, Lmx1b, and Reelin‐Lmx1b neurons expressed Fos in laminae I–II and the lateral reticulated area in wild‐type mice and, therefore, participate in nociceptive circuits. Together, our data suggest that disruption of the Reelin‐signaling pathway results in neuroanatomical abnormalities that contribute to the nociceptive changes that characterize these mutant mice.

    

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