A subset of nuclear-encoded RNAs has to be imported into mitochondria for the proper replication and transcription of the mitochondrial genome and, hence, for proper mitochondrial function. Polynucleotide phosphorylase (PNPase or PNPT1) is one of the very few components known to be involved in this poorly characterized process in mammals. At the organismal level, however, the effect of PNPase dysfunction and impaired mitochondrial RNA import are unknown. By positional cloning, we identified a homozygous PNPT1 missense mutation (c.1424A>G predicting the protein substitution p.Glu475Gly) of a highly conserved PNPase residue within the second RNase-PH domain in a family affected by autosomal-recessive nonsyndromic hearing impairment. In vitro analyses in bacteria, yeast, and mammalian cells showed that the identified mutation results in a hypofunctional protein leading to disturbed PNPase trimerization and impaired mitochondrial RNA import. Immunohistochemistry revealed strong PNPase staining in the murine cochlea, including the sensory hair cells and the auditory ganglion neurons. In summary, we show that a component of the mitochondrial RNA-import machinery is specifically required for auditory function.
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http://dx.doi.org/10.1016/j.ajhg.2012.09.002 | DOI Listing |
J Exp Clin Cancer Res
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School of Medicine, Chinese PLA General Hospital, Nankai University, Beijing, China.
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Department of Endocrinology and Metabolism, Zhuhai People's Hospital (The Affiliated Hospital of Beijing Institute of Technology, Zhuhai Clinical Medical College of Jinan University), Zhuhai, China.
Purpose Of Review: Review the latest data regarding the intersection of adipose tissue (AT) and iron to meet the needs of AT metabolism and the progression of related diseases.
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Commun Biol
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Department of Psychiatry and Psychotherapy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.
Methodological developments in biomedical research are currently moving towards single-cell approaches. This allows for a much better spatial and functional characterization of, for example, the deterioration of cells within a tissue in response to noxae. However, subcellular resolution is also essential to elucidate whether observed impairments are driven by an explicit organelle.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA.
Mitochondrial function is modulated by its interaction with the endoplasmic reticulum (ER). Recent research indicates that these contacts are disrupted in familial models of amyotrophic lateral sclerosis (ALS). We report here that this impairment in the crosstalk between mitochondria and the ER impedes the use of glucose-derived pyruvate as mitochondrial fuel, causing a shift to fatty acids to sustain energy production.
View Article and Find Full Text PDFBMJ Case Rep
January 2025
Department of Neurology, Barwon Health, Geelong, Victoria, Australia.
A male in his 20s presented with episodic headache and subsequently developed episodic unilateral weakness, dysphasia and encephalopathy. These paroxysmal episodes persisted over time with the development of background cognitive impairment and neuropsychiatric symptoms. MRI surveillance demonstrated progressive T2 hyperintensity with focal cortical oedema correlating to symptoms observed during clinical episodes.
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