Wolfram syndrome (WS) is a recessive multisystem disorder defined by the association of diabetes mellitus and optic atrophy, reminiscent of mitochondrial diseases. The role played by mitochondria remains elusive, with contradictory results on the occurrence of mitochondrial dysfunction. We evaluated 13 recessive WS patients by deep clinical phenotyping, including optical coherence tomography (OCT), serum lactic acid at rest and after standardized exercise, brain Magnetic Resonance Imaging, and brain and muscle Magnetic Resonance Spectroscopy (MRS). Finally, we investigated mitochondrial bioenergetics, network morphology, and calcium handling in patient-derived fibroblasts. Our results do not support a primary mitochondrial dysfunction in WS patients, as suggested by MRS studies, OCT pattern of retinal nerve fiber layer loss, and, in fibroblasts, by mitochondrial bioenergetics and network morphology results. However, we clearly found calcium mishandling between endoplasmic reticulum (ER) and mitochondria, which, under specific metabolic conditions of increased energy requirements and in selected tissue or cell types, may turn into a secondary mitochondrial dysfunction. Critically, we showed that Wolframin (WFS1) protein is enriched at mitochondrial-associated ER membranes and that in patient-derived fibroblasts WFS1 protein is completely absent. These findings support a loss-of-function pathogenic mechanism for missense mutations in WFS1, ultimately leading to defective calcium influx within mitochondria.

Calcium mishandling in absence of primary mitochondrial dysfunction drives cellular pathology in Wolfram Syndrome

La Morgia, Chiara
;
Maresca, Alessandra;Gramegna, Laura Ludovica;Scimonelli, Emanuela;Caporali, Leonardo;Del Dotto, Valentina;Evangelisti, Stefania;Bianchini, Claudio;Valentino, Maria Lucia;Liguori, Rocco;Tonon, Caterina;Lodi, Raffaele;Carelli, Valerio
2020

Abstract

Wolfram syndrome (WS) is a recessive multisystem disorder defined by the association of diabetes mellitus and optic atrophy, reminiscent of mitochondrial diseases. The role played by mitochondria remains elusive, with contradictory results on the occurrence of mitochondrial dysfunction. We evaluated 13 recessive WS patients by deep clinical phenotyping, including optical coherence tomography (OCT), serum lactic acid at rest and after standardized exercise, brain Magnetic Resonance Imaging, and brain and muscle Magnetic Resonance Spectroscopy (MRS). Finally, we investigated mitochondrial bioenergetics, network morphology, and calcium handling in patient-derived fibroblasts. Our results do not support a primary mitochondrial dysfunction in WS patients, as suggested by MRS studies, OCT pattern of retinal nerve fiber layer loss, and, in fibroblasts, by mitochondrial bioenergetics and network morphology results. However, we clearly found calcium mishandling between endoplasmic reticulum (ER) and mitochondria, which, under specific metabolic conditions of increased energy requirements and in selected tissue or cell types, may turn into a secondary mitochondrial dysfunction. Critically, we showed that Wolframin (WFS1) protein is enriched at mitochondrial-associated ER membranes and that in patient-derived fibroblasts WFS1 protein is completely absent. These findings support a loss-of-function pathogenic mechanism for missense mutations in WFS1, ultimately leading to defective calcium influx within mitochondria.
2020
La Morgia, Chiara; Maresca, Alessandra; Amore, Giulia; Gramegna, Laura Ludovica; Carbonelli, Michele; Scimonelli, Emanuela; Danese, Alberto; Patergnani, Simone; Caporali, Leonardo; Tagliavini, Francesca; Del Dotto, Valentina; Capristo, Mariantonietta; Sadun, Federico; Barboni, Piero; Savini, Giacomo; Evangelisti, Stefania; Bianchini, Claudio; Valentino, Maria Lucia; Liguori, Rocco; Tonon, Caterina; Giorgi, Carlotta; Pinton, Paolo; Lodi, Raffaele; Carelli, Valerio
File in questo prodotto:
File Dimensione Formato  
Calcium mishandling in absence of primary mitochondrial dysfunction drives cellular pathology in Wolfram Syndrome.pdf

accesso aperto

Tipo: Versione (PDF) editoriale
Licenza: Licenza per Accesso Aperto. Creative Commons Attribuzione (CCBY)
Dimensione 2.43 MB
Formato Adobe PDF
2.43 MB Adobe PDF Visualizza/Apri
41598_2020_61735_MOESM1_ESM.docx

accesso aperto

Tipo: File Supplementare
Licenza: Licenza per Accesso Aperto. Creative Commons Attribuzione (CCBY)
Dimensione 3.32 MB
Formato Microsoft Word XML
3.32 MB Microsoft Word XML Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/752754
Citazioni
  • ???jsp.display-item.citation.pmc??? 18
  • Scopus 31
  • ???jsp.display-item.citation.isi??? 29
social impact