ライフサイエンスコーパス: triadin

1 erited null variants in TRDN-encoded cardiac triadin.

2 ated by its interacting proteins junctin and triadin.

3 milar membrane topology with skeletal muscle triadin.

4 each other and from that of skeletal muscle triadin.

5 ockout of the sarcoplasmic reticulum protein triadin.

6 system, and evaluated CASQ2 interaction with triadin.

7 ssive null mutations in TRDN-encoded cardiac triadin.

8 ne had no effect on calsequestrin binding to triadin.

9 Triadin 1 (TRD) is an integral membrane protein that ass

10 and sequenced cDNAs encoding canine cardiac triadin 1 and 3 but found no evidence for triadin 2.

11 When triadin 1 and junctin were added to the luminal side of

12 In RyRs reassociated with triadin 1 and junctin, adding luminal CSQ produced a sig

13 its the channel at low luminal [Ca], whereas triadin 1 and/or junctin may be required to mediate inte

14 Confirming this, overexpression of triadin 1 in transgenic mouse hearts produced both the 3

15 Here, we show that only triadin 1 is significantly expressed.

16 We conclude that triadin 1 is the triadin isoform most likely to play a r

17 A series of deletional fusion proteins of triadin 1 was generated, and by using metabolically labe

18 assays, the calsequestrin-binding domain of triadin 1 was localized to a single KEKE motif comprised

19 The glycosylation site of triadin 1 was localized to asparagine residue 75, and it

20 an antibody against the unique C terminus of triadin 1 were raised.

21 These results suggest that a complex of CSQ, triadin 1, and junctin confer RyR luminal Ca sensitivity

22 inal auxiliary proteins calsequestrin (CSQ), triadin 1, and junctin in forming the luminal calcium se

23 ryanodine receptors, calsequestrin, junctin, triadin 1, Ca2+-ATPase, or phospholamban.

24 wn to correspond to the glycosylated form of triadin 1, not a distinct triadin 2 isoform as previousl

25 g to calsequestrin by mutational analysis of triadin 1, the major cardiac isoform.

26 including the antibody that recognizes only triadin 1.

27 insignificant (</=5%) compared with that of triadin 1.

28 dine receptor (RyR2), calsequestrin (CASQ2), triadin-1 (Trd) and junctin (Jn) which form a complex in

29 oplasmic reticulum (SR) proteins junctin and triadin-1 and increased SR volume.

30 d near absence of the Casq2-binding proteins triadin-1 and junctin; upregulation of other Ca2+ -bindi

31 Although triadin-1 appeared by SDS-PAGE analysis as a 35/40-kDa d

32 s incomplete glycosylation, we overexpressed triadin-1 as a series of glycoform variants in non-muscl

33 Calsequestrin and triadin-1 both contain N-linked glycans, but about half

34 contain N-linked glycans, but about half of triadin-1 in the heart remains unglycosylated.

35 ified forms of triadin-1 that were seen with triadin-1 only when it is not glycosylated on Asn(75).

36 l sarcoplasmic reticulum, binding to cardiac triadin-1 provides a mechanism by which the Ca(2+)-relea

37 o striking changes in the relative levels of triadin-1 that indicated active breakdown of unglycosyla

38 an accumulation of two new modified forms of triadin-1 that were seen with triadin-1 only when it is

39 Treatment of triadin-1 with the proteasome inhibitor MG-132 led to st

40 ses in the relative levels of unglycosylated triadin-1, proteasome inhibition led to an accumulation

41 own of unglycosylated, but not glycosylated, triadin-1.

42 s with high affinity, while triadin(68-267), triadin(110-267), and triadin(279-674) bind with low aff

43 rially expressed peptides, triadin(110-280), triadin(110-267), and triadin(279-674), but to no other

44 However, triadin(110-280) binds with high affinity, while triadin

45 tor binds to bacterially expressed peptides, triadin(110-280), triadin(110-267), and triadin(279-674)

46 ycosylated form of triadin 1, not a distinct triadin 2 isoform as previously hypothesized.

47 ac triadin 1 and 3 but found no evidence for triadin 2.

48 inity ionic interaction of large portions of triadin; (2) a specific high-affinity binding of a short

49 Triadin(258-280), triadin(267-280), and triadin(258-299)

50 Triadin(258-280), triadin(267-280), and triadin(258-299) all bind to the ryanodine receptor with

51 Triadin(258-280), triadin(267-280), and triadin(258-299) all bind to the r

52 On the other hand, a construct containing triadin(267-280), but preceded by nine residues of heter

53 while triadin(68-267), triadin(110-267), and triadin(279-674) bind with low affinity.

54 des, triadin(110-280), triadin(110-267), and triadin(279-674), but to no other moieties of the protei

55 d be tentatively identified in myocardium as triadin 3, its expression level was insignificant (</=5%

56 din(110-280) binds with high affinity, while triadin(68-267), triadin(110-267), and triadin(279-674)

57 The same three triadin peptides as well as triadin(68-267), when attached to a glutathione column,

58 In addition, HRCBP interacts with triadin, a protein associated with the ryanodine recepto

59 processing of the pre-mRNA encoding cardiac triadin, a protein that functions in regulation of Ca(2+

60 understand this mechanism, we study here how triadin alters [Ca(2+)](rest), Ca(2+) release, and Ca(2+

61 lthough studies suggest that the jSR protein triadin anchors cardiac calsequestrin (Casq2) to RyR2, i

62 re associated with several proteins of which triadin and calsequestrin are the best characterized.

63 Therefore SR-surface docking, targeting of triadin and calsequestrin to the junctional SR domains a

64 e that also includes the ryanodine receptor, triadin and calsequestrin.

65 apparently normal content and disposition of triadin and calsequestrin.

66 view highlights new insights of the roles of triadin and Casq2 derived from gene-targeted knock-out a

67 copy and the presence of a normal pattern of triadin and dihydropyridine receptor.

68 mplex, junctin, which exhibits homology with triadin and is the major 125I-calsequestrin-binding prot

69 Casq2, triadin and junctin form a protein complex that is assoc

70 regulated the interactions of HRC with both triadin and SERCA2a, suggesting a unique mechanism for r

71 ally important domain for attachment between triadin and the ryanodine receptor.

72 ations indicate two types of binding between triadin and the ryanodine receptor: (1) a low-affinity i

73 binding protein known to associate with both triadin and the sarcoplasmic reticulum Ca(2+)-ATPase, an

74 es, antibodies against domains common to all triadins and an antibody against the unique C terminus o

75 a1c (coding for CaV1.2) and Trdn (coding for triadin), and protein levels of calsequestrin-2 (Casq2).

76 These include the ryanodine receptor, triadin, and calsequestrin, which may associate into a s

77 ormalization of the levels of calsequestrin, triadin, and junctin, rescue of electrophysiological and

78 with other jSR proteins, such as junctin and triadin, and partly to its ability to polymerize, in a h

79 n, including laminin alpha2, laminin alpha4, triadin, and phospholamban.

80 results suggest that junctin, calsequestrin, triadin, and the ryanodine receptor form a quaternary co

81 hat forms a quaternary complex with junctin, triadin, and the ryanodine receptor.

82 hat junctin binds directly to calsequestrin, triadin, and the ryanodine receptor.

83 The altered interactions between CSQ2, triadin, and/or junctin and RyR2 may produce an arrhythm

84 e electron microscopy, we find that DHPR and triadin are clustered in foci in differentiating 1B5 cel

85 Furthermore, both cardiac Casq2 and triadin are important for the structural organization of

86 Cardiac calsequestrin (Casq2) and triadin are proteins located in specialized areas of the

87 resulted in significantly reduced levels of triadin, as well as those of the interacting protein cal

88 Either isoform colocalizes with DHPRs and triadin at the cell periphery.

89 emonstrated that the critical amino acids of triadin binding to calsequestrin are the even-numbered r

90 Ryanodine receptor binds to triadin blotted onto nitrocellulose with a KD of 40 nM i

91 oding cardiac calsequestrin), TRDN (encoding triadin), CALM1, CALM2 and CALM3 (encoding identical cal

92 SR) protein, forms a quaternary complex with triadin, calsequestrin and the ryanodine receptor (RyR)

93 ess key triadic proteins, including skeletal triadin, calsequestrin, FK506-binding protein, 12 kD, sa

94 Results indicate that FKBP-12, DHPRalpha1, triadin, calsequestrin, SERCA1 (sarco(endo)plasmic retic

95 In particular, ablation of triadin causes a 50% reduction in the extent of the junc

96 These results suggest that triadin colocalizes with and binds to the ryanodine rece

97 The lumenal domain of triadin contains multiple repeats of alternating lysine

98 ent, resting cytosolic Ca(2+) levels, muscle triadin content and calsequestrin (CSQ) localization to

99 muscles and myotubes showed that the lack of triadin did not prevent skeletal excitation-contraction

100 , mouse MT-1 or human Trisk32, is encoded by triadin exons 1 to 8.

101 This resulted in a total lack of triadin expression in both skeletal and cardiac muscle.

102 We analyzed triadin expression in heart explants from patients with

103 n skeletal muscle showed that the absence of triadin expression was associated with down-regulation o

104 suggest a model in which residues 210-224 of triadin form a beta-strand, with the even-numbered resid

105 ration, a homozygous p.D18fs*13 TRDN-encoded triadin frameshift mutation was discovered in a 10-year-

106 Alternative splicing of a single triadin gene produces multiple triadin isoforms.

107 In humans, mutations in the triadin gene that lead to a reduction in Trisk32 levels

108 g RNA encoded by the antisense strand of the triadin gene, between exons 9 and 11.

109 t, by regulating alternative splicing of the triadin gene.

110 -null mice by removing the first exon of the triadin gene.

111 The cDNAs encoding these three isoforms of triadin have been isolated by reverse transcription-poly

112 out of Trdn-as in mice downregulates cardiac triadin, impairs Ca(2+) handling, and causes premature d

113 erall, our data support an indirect role for triadin in regulating myoplasmic Ca(2+) homeostasis and

114 To unmask the role of triadin in skeletal muscle we engineered pan-triadin-nul

115 (2+) ([Ca(2+)](rest)), suggesting a role for triadins in modulating global intracellular Ca(2+) homeo

116 ly, we have shown that lack of expression of triadins in skeletal muscle cells results in significant

117 It appears that junctin and triadin interact directly in the junctional sarcoplasmic

118 Triadin is a protein of the SR located at the SR-exterio

119 he conserved region of the luminal domain of triadin is able to bind both the ryanodine receptor and

120 Triadin is an integral membrane protein of sarcoplasmic

121 Triadin is an integral membrane protein of the junctiona

122 Triadin is an intrinsic membrane protein first identifie

123 We conclude that triadin is critically important for maintaining the stru

124 ologous region of triadin shows that cardiac triadin is primarily confined to the I-band region of ca

125 However, mechanisms that maintain triadin isoform composition in the heart remain elusive.

126 We conclude that triadin 1 is the triadin isoform most likely to play a role in Ca(2+) rel

127 Several triadin isoforms have been postulated to exist in cardia

128 equences and biochemical analysis, all three triadin isoforms share similar membrane topology with sk

129 g of a single triadin gene produces multiple triadin isoforms.

130 cholamine-induced ventricular arrhythmias in triadin knock-out mice.

131 ased risk for spontaneous Ca(2+) releases in triadin knock-out myocytes and catecholamine-induced ven

132 mics, fluorescent chimeras were expressed in triadin knockout myotubes, and their mobility was compar

133 Triadin knockout syndrome (TKOS) is a potentially lethal

134 Triadin knockout syndrome (TKOS) is a rare, inherited ar

135 Currently, the International Triadin Knockout Syndrome Registry includes 21 patients

136 advances, enrollment into the International Triadin Knockout Syndrome Registry is encouraged to bett

137 We have established the International Triadin Knockout Syndrome Registry to include patients w

138 Triadin knockout was not embryonic or birth-lethal, and

139 which Trdn-as regulates cardiac function and triadin levels in the heart.

140 erations in ryanodine receptor, junctin, and triadin levels in transgenic hearts.

141 Normalization of cardiac triadin levels in Trdn-as knockout cardiomyocytes is suf

142 and functional integrity of the cardiac CRU; triadin loss and the resulting alterations in CRU struct

143 This small, highly charged beta-strand of triadin may tether calsequestrin to the junctional face

144 No triadin null individuals were identified in 599 sudden i

145 Based previously on 5 triadin null patients, TKOS has been characterized by ex

146 and Mg(2+) inhibition between wild-type and triadin-null animals.

147 rates under resting conditions indicate that triadin-null cells also have higher Ca(2+) entry rates a

148 o inhibition with ryanodine, suggesting that triadin-null cells have increased basal RyR1 activity.

149 , BLM studies indicate that, unlike WT-RyR1, triadin-null channels more frequently display atypical g

150 triadin in skeletal muscle we engineered pan-triadin-null mice by removing the first exon of the tria

151 of myotubes and RyR1 channels obtained from triadin-null mice.

152 is and fluorescent FKBP12 binding studies in triadin-null muscles revealed a significant impairment o

153 Unlike WT cells, triadin-null myotubes had chronically elevated [Ca(2+)](

154 data suggest that elevated [Ca(2+)](rest) in triadin-null myotubes is primarily driven by dysregulate

155 receptor (RyR)], and its associated protein, triadin, of skeletal type channels.

156 The binding between intact triadin or expressed triadin peptides and the ryanodine

157 binding between intact triadin or expressed triadin peptides and the ryanodine receptor has been inv

158 The same three triadin peptides as well as triadin(68-267), when attach

159 Triadin plays an important role in Ca(2+) homeostasis in

160 tes cardiac-specific alternative splicing of triadin pre-mRNA and, reflecting this, is essential for

161 efficient recruitment of splicing factors to triadin precursor mRNA.

162 by reduced skeletal muscle and fat mass, and triadin protein expression was upregulated in the heart

163 Here we identified the specific residues of triadin responsible for binding to calsequestrin by muta

164 pha1 and alpha2 subunits of DHPRs, RyRs, and triadin show that the skeletal isoforms of all four prot

165 odies purified from the homologous region of triadin shows that cardiac triadin is primarily confined

166 cosylation sequence that are conserved among triadin splice variants, including the close proximity o

167 ically to the regulated exon and to modulate triadin splicing in vitro.

168 localization to the SR, and interaction with triadin suggest that HRCBP is involved in calcium handli

169 The CRC protein triadin (T95) is localized in the sarcoplasmic reticulum

170 strin genes, which interact with junctin and triadin to form a macromolecular Ca-signaling complex.

171 y1Rs are responsible for targeting DHPRs and triadin to junctional regions.

172 associated with a reduction in the levels of Triadin (TrD) and Junctin (JnC), two proteins that form,

173 ontain dihydropyridine receptors (DHPRs) and triadin, two essential components of CRUs, but no RyRs (

174 Here, we identify the role of triadin using mice with ablation of the Trdn gene (Trdn(

175 ing polyclonal antibodies to skeletal muscle triadin, we have identified and characterized three isof

176 markedly reduced, whereas DHPRa1, SERCA1 and triadin were abnormally accumulated in discrete areas of

177 The amount of RyR1 and triadin were markedly reduced, whereas DHPRa1, SERCA1 an

178 se cascade (ryanodine receptor, junctin, and triadin) were downregulated, whereas Ca2+-uptake protein

179 e also found in the common lumenal domain of triadin, which likewise is capable of binding to calsequ