scholarly journals Progress in Understanding the Pathogenesis of Oculopharyngeal Muscular Dystrophy

Author(s):  
Xueping Fan ◽  
Guy A. Rouleau

Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping (ptosis), swallowing difficulties (dysphagia), and proximal limb weakness. The autosomal dominant form of this disease is caused by expansions of a (GCG)6 repeat to (GCG)8-13 in the PABPN1 gene. These mutations lead to the expansion of a polyalanine stretch from 10 to 12-17 alanines in the N-terminal domain of PABPN1. Mutated PABPN1 (mPABPN1) induces the formation of muscle intranuclear inclusions that are thought to be the hallmark of this disease. In this review, we discuss: 1) OPMD genetics and PABPN1 function studies; 2) diseases caused by polyalanine expansions and cellular polyalanine toxicity; 3) mPABPN1-induced intranuclear inclusion toxicity; 4) role of oligomerization of mPABPN1 in the formation and toxicity of OPMD intranuclear inclusions and; 5) recruitment of subcellular components to the OPMD inclusions. We present a potential molecular mechanism for OPMD pathogenesis that accounts for these observations.

Author(s):  
Xueping Fan ◽  
Christiane Messaed ◽  
Patrick Dion ◽  
Janet Laganiere ◽  
Bernard Brais ◽  
...  

Background:Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive ptosis, dysphagia and proximal limb weakness. The autosomal dominant form of this disease is caused by short expansions of a (GCG)6 repeat to (GCG)8-13 in the PABPN1 gene. The mutations lead to the expansion of a polyalanine stretch from 10 to 12-17 alanines in the N-terminus of PABPN1. The mutated PABPN1 (mPABPN1) induces the formation of intranuclear filamentous inclusions that sequester poly(A) RNA and are associated with cell death.Methods:Human fetal brain cDNA library was used to look for PABPN1 binding proteins using yeast two-hybrid screen. The protein interaction was confirmed by GST pull-down and co-immunoprecipitation assays. Oculopharyngeal muscular dystrophy cellular model and OPMD patient muscle tissue were used to check whether the PABPN1 binding proteins were involved in the formation of OPMD intranuclear inclusions.Results:We identify two PABPN1 interacting proteins, hnRNP A1 and hnRNP A/B. When co-expressed with mPABPN1 in COS-7 cells, predominantly nuclear protein hnRNP A1 and A/B co-localize with mPABPN1 in the insoluble intranuclear aggregates. Patient studies showed that hnRNP A1 is sequestered in OPMD nuclear inclusions.Conclusions:The hnRNP proteins are involved in mRNA processing and mRNA nucleocytoplasmic export, sequestering of hnRNPs in OPMD intranuclear aggregates supports the view that OPMD intranuclear inclusions are “poly(A) RNA traps”, which would interfere with RNA export, and cause muscle cell death.


2012 ◽  
Vol 40 (5) ◽  
pp. 1117-1122 ◽  
Author(s):  
Giovanna Sanna ◽  
Maria Grazia Del Giudice ◽  
Claudia Crosio ◽  
Ciro Iaccarino

Mutations in LRRK2 (leucine-rich repeat kinase 2) (also known as PARK8 or dardarin) are responsible for the autosomal-dominant form of PD (Parkinson's disease). LRRK2 mutations were found in approximately 3–5% of familial and 1–3% of sporadic PD cases with the highest prevalence (up to 40%) in North Africans and Ashkenazi Jews. To date, mutations in LRRK2 are a major genetic risk factor for familial and sporadic PD. Despite the fact that 8 years have passed from the establishment of the first link between PD and dardarin in 2004, the pathophysiological role of LRRK2 in PD onset and progression is far from clearly defined. Also the generation of different LRRK2 transgenic or knockout animals has not provided new hints on the function of LRRK2 in the brain. The present paper reviews recent evidence regarding a potential role of LRRK2 in the regulation of membrane trafficking from vesicle generation to the movement along cytoskeleton and finally to vesicle fusion with cell membrane.


1998 ◽  
Vol 2 (3) ◽  
pp. 172-179 ◽  
Author(s):  
David Hogg ◽  
Herbert Brill ◽  
Ling Liu ◽  
Jose Monzon ◽  
Anne Summers ◽  
...  

Background: Approximately 8 to 12% of melanoma appears to be inherited in an autosomal dominant form. Although most early stage melanomas can be treated successfully by simple surgical excision, patients with advanced disease are rarely cured even with aggressive chemotherapy and/or immunotherapy. Objective: There is now compelling evidence that germline mutations of the CDKN2A gene on chromosome 9p21 predispose to melanoma in a subset of melanoma-prone families. In this article the evidence for the role of CDKN2A in the genesis of familial melanoma is reviewed and the implications of genetic testing in families with this disease are discussed. Conclusion: The identification and subsequent surveillance of unaffected individuals who have a genetic predisposition to melanoma may lead to the detection of early (curable) melanomas and to a reduction in mortality.


2017 ◽  
Vol 6 (1) ◽  
pp. 14-18
Author(s):  
Elise Alexandra Kikis ◽  
Megan Elizabeth Mastey

Emery-Dreifuss Muscular Dystrophy (EDMD) is a type of muscular dystrophy characterized by contractures, or shortening of muscles or joints in the elbows and Achilles tendons, muscle wasting and weakness as well as cardiomyopathy. There are two main forms of inherited EDMD, X-linked recessive and autosomal dominant. There is also a rarer form of autosomal recessive inheritance with only a few cases ever reported. The X-linked form of EDMD is caused by mutation of the STA gene that encodes the protein emerin, while the autosomal dominant form is caused by a missense mutation on the LMNA gene, which encodes lamin A/C proteins. Both emerin and lamin A/C are nuclear envelope proteins that interact with other proteins to create a connective network that attaches the nuclear lamina to the cytoskeleton. These nuclear envelope proteins interact via accessory proteins to chromatin and also thereby stimulate gene expression. The exact mechanism of how mutations in these genes lead to muscular dystrophy is not well understood. The “structural hypothesis,” states that the absence of these envelope proteins result in a weakened cell and would eventually end in nuclear disruption. The “gene regulatory hypothesis” states that emerin and lamin may be transcription factors whose absence results in tissue-specific effects. This review will addresses these hypotheses, describes what is known about the cell and molecular biology underlying EDMD and considers recent as advances in therapeutics.


2019 ◽  
Vol 12 (9) ◽  
pp. e230521
Author(s):  
Mhairi Kathryn Nisbet ◽  
Louise Marshall

Oculopharyngeal muscular dystrophy (OPMD) is a relatively rare, adult-onset disorder characterised by proximal limb weakness, progressive eyelid drooping and swallowing difficulties. Preliminary research suggests there could be a link between OPMD and dementia; however, the current literature is relatively limited and inconsistent. This case study describes a 75-year-old female with OPMD, presenting to an older adults community mental health team with memory problems and word finding difficulties. A neuropsychological assessment was carried out. The results of her assessment were difficult to interpret; she demonstrated impairments in most cognitive domains tested and her presentation did not appear to reflect any typical dementia profile. It was thought she was most likely presenting with a dementia; however, the exact aetiology remains unclear. The dementia could be a result of OPMD, vascular changes or both. This report emphasises the need for further research into the possible causal link between OPMD and dementia/cognitive decline.


1998 ◽  
Vol 11 (2) ◽  
pp. 71-77 ◽  
Author(s):  
Stephen Salloway ◽  
Joseph Hong

Mental disorders due to cerebral microvascular disease have been known for over 100 years. Recently, an autosomal dominant form of cerebral arteriopathy (CADASIL) has been described in association with a Notch3 family gene on the short arm of chromosome 19. CADASIL causes subcortical lacunar infarction and dementia in over 80% of cases and depression in a large proportion of patients. Clinically, CADASIL may appear to be very similar to hypertensive microvascular disease (Binswanger's disease), a condition that is seen in the elderly. This article reviews the clinical, pathologic, and genetic features of CADASIL. CADASIL is of interest to neurologists and psychiatrists because it is the first syndrome of vascular dementia and depression with an identified gene. How the gene causes the widespread arteriopathy is not yet known. Insights gained from the study of CADASIL should help us better understand its etiology, as well as the options for treatment of the more common forms of microvascular disease seen in the elderly.


2018 ◽  
Vol 2 (2) ◽  
pp. 73
Author(s):  
Naida Lojo-Kadric ◽  
Zelija Velija Asimi ◽  
Jasmin Ramic ◽  
Ksenija Radic ◽  
Lejla Pojskic

MODY (maturity-onset diabetes of the young) is an autosomal dominant form of diabetes that is usually manifested before the 25-year of life. This type of diabetes is caused by defects in the primary insulin secretion. There are several types of MODY, which are monogenic diseases, where mutations in a single gene are responsible for a particular type of MODY. Currently, there are eleven types of MODY, from which the most common types are MODY 2 and MODY 3 (with mutations on GCK and HNF1A genes, respectively). We identified very rare MODY 7 type of diabetes in three family members by MLPA analysis.


2000 ◽  
Vol 67 (2) ◽  
pp. 302-310 ◽  
Author(s):  
Sandra Disse-Nicodème ◽  
Jean-Michel Achard ◽  
Isabelle Desitter ◽  
Anne-Marie Houot ◽  
Albert Fournier ◽  
...  

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