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Biology subjects

Marquardt, T.

Publications and source records attributed to Marquardt, T..

3 recordsLinked to original sources

Treatment with 2-phospho-L-ascorbic acid mitigates biochemical phenotypes of heme oxygenase 1 deficiency

Heme oxygenase 1 (HO-1) deficiency is a fatal genetic disorder characterized by impaired heme catabolism, leading to excessive oxidative damage and cell death. Despite evidence from non-human models suggesting mitochondrial dysfunction, the precise pathomechanisms in humans remain unclear, resulting in a lack of effective treatments. Using patient-derived lymphoblastoid cells and HO-1 knockout HEK293T cell models, we demonstrate that HO-1 deficiency is associated with altered mitochondrial morphology and impaired mitochondrial function. Furthermore, it is linked to significant ascorbic acid depletion, accompanied by compensatory upregulation of SVCT2, a key ascorbic acid transporter. Treatment with 2-phospho-L-ascorbic acid, a stable vitamin C analog, restores intracellular ascorbic acid levels and protects cells from hemin-induced cytotoxicity, highlighting its potential as a novel therapeutic strategy for HO-1 deficiency. Our study underscores the critical role of oxidative stress and mitochondrial dysfunction in HO-1 deficiency, paving the way for targeted interventions in this devastating disorder.

molecular biology↗

Orphan nuclear receptors Err2 and 3 promote a feature-specific terminal differentiationprogram underlying gamma motor neuron function and proprioceptive movement control

Motor neurons are commonly thought of as mere relays between the central nervous system and the movement apparatus, yet, in mammals about one-third of them function exclusively as regulators of muscle proprioception. How these gamma motor neurons acquire properties to function differently from the muscle force-producing alpha motor neurons remains unclear. Here, we found that upon selective loss of the orphan nuclear receptors Err2 and Err3 (Err2/3) in mice, gamma motor neurons acquire characteristic structural (e.g. synaptic wiring), but not functional (e.g. physiological firing rates) properties necessary for regulating muscle proprioception, thus disrupting gait and precision movements in vivo. Moreover, Err2/3 operate via transcriptional activation of neural activity modulators, one of which (Kcna10) promoted gamma motor neuron functional properties. Our work identifies a long-sought mechanism specifying gamma motor neuron properties necessary for proprioceptive movement control, which implies a feature-specific terminal differentiation program implementing neuron subtype-specific functional but not structural properties. SummaryThe transcription factors Err2 and 3 promote functional properties in a subset of motor neurons necessary for executing precise movements.

neuroscience↗

A schizophrenia risk locus alters brain metal transport and plasma glycosylation

A common missense variant in SLC39A8 is convincingly associated with schizophrenia and several additional phenotypes. Homozygous loss-of-function mutations in SLC39A8 result in undetectable serum manganese (Mn) and a Congenital Disorder of Glycosylation (CDG) due to the exquisite sensitivity of glycosyltransferases to Mn concentration. Here, we identified several Mn-related changes in human carriers of the common SLC39A8 missense allele. Analysis of structural brain MRI scans showed a dose-dependent change in the ratio of T2w to T1w signal in several regions. Comprehensive trace element analysis confirmed a specific reduction of only serum Mn, and plasma protein N-glycome profiling revealed reduced complexity and branching. N-glycome profiling from two individuals with SLC39A8-CDG showed similar but more severe alterations in branching that improved with Mn supplementation, suggesting that the common variant exists on a spectrum of hypofunction with potential for reversibility. Characterizing the functional impact of this variant will enhance our understanding of schizophrenia pathogenesis and identify novel therapeutic targets and biomarkers of disease. SummaryA common variant in the manganese transporter SLC39A8 is associated with numerous phenotypes including schizophrenia. Mealer et. al. presents an in-depth analysis of brain MRI and plasma glycomics in human carriers of the common variant, identifying several manganese-related changes with potential for diagnostic and therapeutic biomarker development.

biochemistry↗