title: Calcium Handling by Endoplasmic Reticulum and Mitochondria in a Cell Model of Huntington's Disease.
abstract: Huntington disease (HD) is caused by the CAG (Q) expansion in exon 1 of the IT15 gene encoding a polyglutamine (poly-Q) stretch of the Huntingtin protein (Htt). In the wild type protein, the repeats specify a stretch of up 34 Q in the N-terminal portion of Htt. In the pathological protein (mHtt) the poly-Q tract is longer. Proteolytic cleavage of the protein liberates an N-terminal fragment containing the expanded poly-Q tract becomes harmful to cells, in particular to striatal neurons. The fragments cause the transcriptional dysfunction of genes that are essential for neuronal survival. Htt, however, could also have non-transcriptional effects, e.g. it could directly alter Ca2+ homeostasis and/or mitochondrial morphology and function. Ca2+ dyshomeostasis and mitochondrial dysfunction are considered important in the molecular aetiology of the disease. Here we have analyzed the effect of the overexpression of Htt fragments (18Q, wild type form, wtHtt and 150Q mutated form, mHtt) on Ca2+ homeostasis in striatal neuronal precursor cells (Q7/7). We have found that the transient overexpression of the Htt fragments increases Ca2+ transients in the mitochondria of cells stimulated with Ca2+-mobilizing agonists. The bulk Ca2+ transients in the cytosol were unaffected, but the Ca2+ content of the endoplasmic reticulum was significantly decreased in the case of mHtt expression. To rule out possible transcriptional effects due to the presence of mHtt, we have measured the mRNA level of a subunit of the respiratory chain complex II, whose expression is commonly altered in many HD models. No effects on the mRNA level was found suggesting that, in our experimental condition, transcriptional action of Htt is not occurring and that the effects on Ca2+ homeostasis were dependent to non-transcriptional mechanisms.
authors.affiliation: Biomedical Sciences, University of Padova, Padova, Italy.
authors.forename: Agnese
authors.initials: A
authors.lastname: De Mario
authors.affiliation: Venetian Institute for Molecular Medicine, Padua, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Scarlatti
authors.affiliation: Biomedical Sciences, University of Padova, Padova, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Costiniti
authors.affiliation: Pediatric Hemato Oncology Clinic, Woman and Child Health, University of Padova, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Primerano
authors.affiliation: Biomedical Sciences, University of Padova, Padova, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Lopreiato
authors.affiliation: Biomedical Sciences, University of Padova, Padova, Italy.
authors.forename: Tito
authors.initials: T
authors.lastname: Calì
authors.forename: Marisa
authors.initials: M
authors.lastname: Brini
authors.affiliation: Biology, University of Padova and VIMM Padova, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Giacomello
authors.affiliation: Biomedical Sciences, University of Padova, Padova, Italy; Venetian Institute of Molecular Medicine, Padova, Italy.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Carafoli
references.citation: Neuron. 1998 Jul;21(1):13-26
references.pmid: 9697848
references.citation: Mol Biol Cell. 2006 Apr;17 (4):1652-63
references.pmid: 16452635
references.citation: Drug Discov Today. 2014 Jul;19(7):956-62
references.pmid: 24662036
references.citation: EMBO Mol Med. 2010 Dec;2(12):490-503
references.pmid: 21069748
references.citation: Nat Neurosci. 2002 Aug;5(8):731-6
references.pmid: 12089530
references.citation: Science. 1997 Sep 26;277(5334):1990-3
references.pmid: 9302293
references.citation: Nat Genet. 1998 Feb;18(2):150-4
references.pmid: 9462744
references.citation: J Biol Chem. 2008 Feb 29;283(9):5780-9
references.pmid: 18156184
references.citation: Clin Genet. 2004 Apr;65(4):267-77
references.pmid: 15025718
references.citation: J Neurochem. 1994 Sep;63(3):1033-41
references.pmid: 7914221
references.citation: J Neurochem. 2005 Jun;93(6):1361-70
references.pmid: 15935052
references.citation: Nat Med. 1999 Oct;5(10):1194-8
references.pmid: 10502825
references.citation: PLoS Genet. 2007 May 11;3(5):e82
references.pmid: 17500595
references.citation: Brain Res Bull. 2001 Sep 15;56(2):111-7
references.pmid: 11704347
references.citation: Cell. 1996 Nov 1;87(3):493-506
references.pmid: 8898202
references.citation: Hum Mol Genet. 2013 Mar 1;22(5):989-1004
references.pmid: 23197653
references.citation: Nat Neurosci. 2014 Jun;17 (6):822-31
references.pmid: 24836077
references.citation: Proc Natl Acad Sci U S A. 2004 Dec 14;101(50):17404-9
references.pmid: 15585581
references.citation: Biofactors. 2011 May-Jun;37(3):206-18
references.pmid: 21674644
references.citation: Physiol Rev. 2010 Jul;90(3):905-81
references.pmid: 20664076
references.citation: Ann Neurol. 1996 Mar;39(3):385-9
references.pmid: 8602759
references.citation: Ann Neurol. 1998 Mar;43(3):397-400
references.pmid: 9506560
references.citation: Neuron. 2003 Jul 17;39(2):227-39
references.pmid: 12873381
references.citation: Neurochem Res. 2001 Apr;26(4):419-24
references.pmid: 11495354
references.citation: Hum Mol Genet. 2013 Oct 1;22(19):3869-82
references.pmid: 23720495
references.citation: J Biol Chem. 2006 Nov 17;281(46):34785-95
references.pmid: 16973623
references.citation: Hum Mol Genet. 1995 Aug;4(8):1365-71
references.pmid: 7581375
references.citation: J Neuropathol Exp Neurol. 1998 May;57(5):369-84
references.pmid: 9596408
references.citation: Mol Cell. 2002 Aug;10 (2):259-69
references.pmid: 12191472
references.citation: FEBS Lett. 1968 Aug;1(3):153-155
references.pmid: 11945279
references.citation: Trends Neurosci. 2001 Mar;24(3):182-8
references.pmid: 11182459
references.citation: Front Mol Neurosci. 2013 Nov 25;6:42
references.pmid: 24324398
references.citation: Hum Mol Genet. 2004 Jul 15;13(14 ):1407-20
references.pmid: 15163634
references.citation: J Biol Chem. 1995 Apr 28;270(17):9896-903
references.pmid: 7730373
references.citation: J Neurochem. 2015 Aug;134(4):652-67
references.pmid: 25963273
references.citation: Hum Mol Genet. 2014 Nov 21;:null
references.pmid: 25416283
references.citation: Exp Neurol. 1998 Jul;152(1):34-40
references.pmid: 9682010
references.citation: J Neurochem. 2005 Dec;95(6):1521-40
references.pmid: 16300642
references.citation: Prion. 2013 Jan-Feb;7(1):76-84
references.pmid: 23324594
references.citation: J Neurochem. 2010 Jul;114(1):1-12
references.pmid: 20403078
references.citation: Hum Mol Genet. 1998 May;7(5):783-90
references.pmid: 9536081
references.citation: Nat Med. 2011 Mar;17 (3):377-82
references.pmid: 21336284
references.citation: Biochem Biophys Res Commun. 2004 Oct 1;322(4):1310-7
references.pmid: 15336977
references.citation: Hum Mol Genet. 2002 Aug 15;11(17):1953-65
references.pmid: 12165557
references.citation: Crit Rev Biochem Mol Biol. 2001 Apr;36(2):107-260
references.pmid: 11370791
references.citation: Hum Mol Genet. 2015 Nov 17;:null
references.pmid: 26577153
references.citation: Exp Neurol. 2001 Jun;169(2):340-50
references.pmid: 11358447
references.citation: Cell. 1995 Jun 2;81(5):811-23
references.pmid: 7774020
references.citation: Hum Mol Genet. 2000 Nov 22;9(19):2799-809
references.pmid: 11092756
references.citation: Science. 1998 Jun 12;280(5370):1763-6
references.pmid: 9624056
references.citation: Cell. 2010 Jul 23;142(2):270-83
references.pmid: 20655468
references.citation: Mol Cell. 2010 Apr 23;38(2):280-90
references.pmid: 20417605
references.citation: Mol Cell Biochem. 2005 Jan;269(1-2):143-52
references.pmid: 15786727
references.citation: Mech Ageing Dev. 2006 Feb;127(2):217-20
references.pmid: 16289240
references.citation: Hum Mol Genet. 2006 Oct 15;15(20):3063-81
references.pmid: 16968735
references.citation: Neurobiol Dis. 2008 Jul;31(1):80-8
references.pmid: 18502655
references.citation: J Neurosci. 2007 Dec 12;27(50):13614-23
references.pmid: 18077673
references.citation: J Neurosci. 2008 Mar 12;28(11):2783-92
references.pmid: 18337408
references.citation: Science. 1993 Oct 29;262(5134):744-7
references.pmid: 8235595
references.citation: Front Neurol. 2013 Oct 23;4:127
references.pmid: 24167500
references.citation: Nature. 1992 Jul 23;358(6384):325-7
references.pmid: 1322496
references.citation: J Neurochem. 2007 Apr;101(1):241-9
references.pmid: 17394466