A human mitochondrial poly(A) polymerase mutation reveals the complexities of post-transcriptional mitochondrial gene expression

2.50
Hdl Handle:
http://hdl.handle.net/11287/593831
Title:
A human mitochondrial poly(A) polymerase mutation reveals the complexities of post-transcriptional mitochondrial gene expression
Authors:
Wilson, W. C.; Hornig-Do, H. T.; Bruni, F.; Chang, J. H.; Jourdain, A. A.; Martinou, J. C.; Falkenberg, M.; Spahr, H.; Larsson, N. G.; Lewis, R. J.; Hewitt, L.; Basle, A.; Cross, H. E.; Tong, L.; Lebel, R. R.; Crosby, Andrew H.; Chrzanowska-Lightowlers, Z. M.; Lightowlers, R. N.
Abstract:
The p.N478D missense mutation in human mitochondrial poly(A) polymerase (mtPAP) has previously been implicated in a form of spastic ataxia with optic atrophy. In this study, we have investigated fibroblast cell lines established from family members. The homozygous mutation resulted in the loss of polyadenylation of all mitochondrial transcripts assessed; however, oligoadenylation was retained. Interestingly, this had differential effects on transcript stability that were dependent on the particular species of transcript. These changes were accompanied by a severe loss of oxidative phosphorylation complexes I and IV, and perturbation of de novo mitochondrial protein synthesis. Decreases in transcript polyadenylation and in respiratory chain complexes were effectively rescued by overexpression of wild-type mtPAP. Both mutated and wild-type mtPAP localized to the mitochondrial RNA-processing granules thereby eliminating mislocalization as a cause of defective polyadenylation. In vitro polyadenylation assays revealed severely compromised activity by the mutated protein, which generated only short oligo(A) extensions on RNA substrates, irrespective of RNA secondary structure. The addition of LRPPRC/SLIRP, a mitochondrial RNA-binding complex, enhanced activity of the wild-type mtPAP resulting in increased overall tail length. The LRPPRC/SLIRP effect although present was less marked with mutated mtPAP, independent of RNA secondary structure. We conclude that (i) the polymerase activity of mtPAP can be modulated by the presence of LRPPRC/SLIRP, (ii) N478D mtPAP mutation decreases polymerase activity and (iii) the alteration in poly(A) length is sufficient to cause dysregulation of post-transcriptional expression and the pathogenic lack of respiratory chain complexes.
Citation:
Hum Mol Genet. 2014 Dec 1;23(23):6345-55.
Publisher:
Oxford Journals
Journal:
Human molecular genetics
Issue Date:
1-Dec-2014
URI:
http://hdl.handle.net/11287/593831
DOI:
10.1093/hmg/ddu352
PubMed ID:
25008111
Additional Links:
http://hmg.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=25008111
Note:
This article is available via Open Access. Please click on the 'Additional Link' above to access the full-text.
Type:
Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't
Language:
eng
ISSN:
1460-2083
Appears in Collections:
2014 RD&E publications; Honorary contracts publications

Full metadata record

DC FieldValue Language
dc.contributor.authorWilson, W. C.en
dc.contributor.authorHornig-Do, H. T.en
dc.contributor.authorBruni, F.en
dc.contributor.authorChang, J. H.en
dc.contributor.authorJourdain, A. A.en
dc.contributor.authorMartinou, J. C.en
dc.contributor.authorFalkenberg, M.en
dc.contributor.authorSpahr, H.en
dc.contributor.authorLarsson, N. G.en
dc.contributor.authorLewis, R. J.en
dc.contributor.authorHewitt, L.en
dc.contributor.authorBasle, A.en
dc.contributor.authorCross, H. E.en
dc.contributor.authorTong, L.en
dc.contributor.authorLebel, R. R.en
dc.contributor.authorCrosby, Andrew H.en
dc.contributor.authorChrzanowska-Lightowlers, Z. M.en
dc.contributor.authorLightowlers, R. N.en
dc.date.accessioned2016-01-19T12:35:30Zen
dc.date.available2016-01-19T12:35:30Zen
dc.date.issued2014-12-01en
dc.identifier.citationHum Mol Genet. 2014 Dec 1;23(23):6345-55.en
dc.identifier.issn1460-2083en
dc.identifier.pmid25008111en
dc.identifier.doi10.1093/hmg/ddu352en
dc.identifier.urihttp://hdl.handle.net/11287/593831en
dc.description.abstractThe p.N478D missense mutation in human mitochondrial poly(A) polymerase (mtPAP) has previously been implicated in a form of spastic ataxia with optic atrophy. In this study, we have investigated fibroblast cell lines established from family members. The homozygous mutation resulted in the loss of polyadenylation of all mitochondrial transcripts assessed; however, oligoadenylation was retained. Interestingly, this had differential effects on transcript stability that were dependent on the particular species of transcript. These changes were accompanied by a severe loss of oxidative phosphorylation complexes I and IV, and perturbation of de novo mitochondrial protein synthesis. Decreases in transcript polyadenylation and in respiratory chain complexes were effectively rescued by overexpression of wild-type mtPAP. Both mutated and wild-type mtPAP localized to the mitochondrial RNA-processing granules thereby eliminating mislocalization as a cause of defective polyadenylation. In vitro polyadenylation assays revealed severely compromised activity by the mutated protein, which generated only short oligo(A) extensions on RNA substrates, irrespective of RNA secondary structure. The addition of LRPPRC/SLIRP, a mitochondrial RNA-binding complex, enhanced activity of the wild-type mtPAP resulting in increased overall tail length. The LRPPRC/SLIRP effect although present was less marked with mutated mtPAP, independent of RNA secondary structure. We conclude that (i) the polymerase activity of mtPAP can be modulated by the presence of LRPPRC/SLIRP, (ii) N478D mtPAP mutation decreases polymerase activity and (iii) the alteration in poly(A) length is sufficient to cause dysregulation of post-transcriptional expression and the pathogenic lack of respiratory chain complexes.en
dc.language.isoengen
dc.publisherOxford Journalsen
dc.relation.urlhttp://hmg.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=25008111en
dc.titleA human mitochondrial poly(A) polymerase mutation reveals the complexities of post-transcriptional mitochondrial gene expressionen
dc.typeJournal Articleen
dc.typeResearch Support, N.I.H., Extramuralen
dc.typeResearch Support, Non-U.S. Gov'ten
dc.identifier.journalHuman molecular geneticsen
dc.description.noteThis article is available via Open Access. Please click on the 'Additional Link' above to access the full-text.en

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