Limits...
RNA polymerase III drives alternative splicing of the potassium channel-interacting protein contributing to brain complexity and neurodegeneration.

Massone S, Vassallo I, Castelnuovo M, Fiorino G, Gatta E, Robello M, Borghi R, Tabaton M, Russo C, Dieci G, Cancedda R, Pagano A - J. Cell Biol. (2011)

Bottom Line: We found that IL1-α-dependent up-regulation of 38A, a small ribonucleic acid (RNA) polymerase III-transcribed RNA, drives the synthesis of an alternatively spliced form of the potassium channel-interacting protein (KCNIP4).Notably, synthesis of the variant KCNIP4 isoform is also detrimental to brain physiology, as it results in the concomitant blockade of the fast kinetics of potassium channels.This alternative splicing shift is observed at high frequency in tissue samples from Alzheimer's disease patients, suggesting that RNA polymerase III cogenes may be upstream determinants of alternative splicing that significantly contribute to homeostasis and pathogenesis in the brain.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Oncology, Biology, and Genetics, National Institute for Cancer Research, 16132 Genoa, Italy.

ABSTRACT
Alternative splicing generates protein isoforms that are conditionally or differentially expressed in specific tissues. The discovery of factors that control alternative splicing might clarify the molecular basis of biological and pathological processes. We found that IL1-α-dependent up-regulation of 38A, a small ribonucleic acid (RNA) polymerase III-transcribed RNA, drives the synthesis of an alternatively spliced form of the potassium channel-interacting protein (KCNIP4). The alternative KCNIP4 isoform cannot interact with the γ-secretase complex, resulting in modification of γ-secretase activity, amyloid precursor protein processing, and increased secretion of β-amyloid enriched in the more toxic Aβ x-42 species. Notably, synthesis of the variant KCNIP4 isoform is also detrimental to brain physiology, as it results in the concomitant blockade of the fast kinetics of potassium channels. This alternative splicing shift is observed at high frequency in tissue samples from Alzheimer's disease patients, suggesting that RNA polymerase III cogenes may be upstream determinants of alternative splicing that significantly contribute to homeostasis and pathogenesis in the brain.

Show MeSH

Related in: MedlinePlus

ncRNA expression and alternative splicing in AD cases. (A) 38A expression in AD cases (orange bars) and nADc individuals (green bars) as determined by quantitative real-time RT-PCR. AD cases 124 and 1,024 have a familiar genetic origin. The amplification product dissociation curves unambiguously distinguish the RNAs of interest by peaks at specific temperatures (insets). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged results are also reported. (B) Real-time RT-PCR quantitative detection of KCNIP4 splice variant synthesis in AD patients and nADc individuals. Results are reported as the splice variant ratio (KCNIP4 Var IV vs. Var I). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged ratios are also reported. The dissociation curves (insets) show that the splice variants of interest are unambiguously distinguishable by peaks at specific temperatures. DSE, distal sequence element.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC3105541&req=5

fig7: ncRNA expression and alternative splicing in AD cases. (A) 38A expression in AD cases (orange bars) and nADc individuals (green bars) as determined by quantitative real-time RT-PCR. AD cases 124 and 1,024 have a familiar genetic origin. The amplification product dissociation curves unambiguously distinguish the RNAs of interest by peaks at specific temperatures (insets). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged results are also reported. (B) Real-time RT-PCR quantitative detection of KCNIP4 splice variant synthesis in AD patients and nADc individuals. Results are reported as the splice variant ratio (KCNIP4 Var IV vs. Var I). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged ratios are also reported. The dissociation curves (insets) show that the splice variants of interest are unambiguously distinguishable by peaks at specific temperatures. DSE, distal sequence element.

Mentions: As AD, the most common neurodegenerative disorder, is characterized by an aberrant Aβ secretion, we hypothesized a possible overexpression of 38A in AD cases where it would play an active role in the onset and/or maintenance of pathological manifestations. First, we measured by quantitative real-time RT-PCR the levels of 38A RNA in postmortem cerebral cortex samples obtained from 17 AD patients and 10 non-AD control (nADc) individuals (Table S1). Results evidenced that AD cases tend to overexpress 38A (10.45-fold on average with respect to the nADc individuals), thus correlating the synthesis of this ncRNA with the AD phenotype. At present, we are not able to determine with statistic significance whether there is a correlation between 38A increment and a specific clinical or pathological marker. To date, we can only confirm that there is a significant positive correlation between expression of 38A and AD and a negative correlation with non-AD cases. This general conclusion is reinforced by inspection of some cases that might represent exceptions: (a) controls with higher levels of 38A are case 5, characterized by severe chronic obstructive pulmonary disease and likely hypoxic cerebral damage, and case 963, who was a cognitively normal subject but with a high load of angiopathy and a Braak stage III amyloid status; (b) the AD patient with the lowest 38A level is case 124, who is a familial AD case carrying mutated PS1 and in which PS1 loss/gain of function might exert a predominant role in comparison to 38A (Fig. 7 A). The unaltered transcription of the PolIII-transcribed 5S rRNA in the aforementioned samples indicated that the phenomenon is caused by the specific overexpression of 38A rather than a general increase of PolIII activity (unpublished data).


RNA polymerase III drives alternative splicing of the potassium channel-interacting protein contributing to brain complexity and neurodegeneration.

Massone S, Vassallo I, Castelnuovo M, Fiorino G, Gatta E, Robello M, Borghi R, Tabaton M, Russo C, Dieci G, Cancedda R, Pagano A - J. Cell Biol. (2011)

ncRNA expression and alternative splicing in AD cases. (A) 38A expression in AD cases (orange bars) and nADc individuals (green bars) as determined by quantitative real-time RT-PCR. AD cases 124 and 1,024 have a familiar genetic origin. The amplification product dissociation curves unambiguously distinguish the RNAs of interest by peaks at specific temperatures (insets). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged results are also reported. (B) Real-time RT-PCR quantitative detection of KCNIP4 splice variant synthesis in AD patients and nADc individuals. Results are reported as the splice variant ratio (KCNIP4 Var IV vs. Var I). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged ratios are also reported. The dissociation curves (insets) show that the splice variants of interest are unambiguously distinguishable by peaks at specific temperatures. DSE, distal sequence element.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3105541&req=5

fig7: ncRNA expression and alternative splicing in AD cases. (A) 38A expression in AD cases (orange bars) and nADc individuals (green bars) as determined by quantitative real-time RT-PCR. AD cases 124 and 1,024 have a familiar genetic origin. The amplification product dissociation curves unambiguously distinguish the RNAs of interest by peaks at specific temperatures (insets). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged results are also reported. (B) Real-time RT-PCR quantitative detection of KCNIP4 splice variant synthesis in AD patients and nADc individuals. Results are reported as the splice variant ratio (KCNIP4 Var IV vs. Var I). Error bars represent SD of three independent real-time RT-PCR determinations. The averaged ratios are also reported. The dissociation curves (insets) show that the splice variants of interest are unambiguously distinguishable by peaks at specific temperatures. DSE, distal sequence element.
Mentions: As AD, the most common neurodegenerative disorder, is characterized by an aberrant Aβ secretion, we hypothesized a possible overexpression of 38A in AD cases where it would play an active role in the onset and/or maintenance of pathological manifestations. First, we measured by quantitative real-time RT-PCR the levels of 38A RNA in postmortem cerebral cortex samples obtained from 17 AD patients and 10 non-AD control (nADc) individuals (Table S1). Results evidenced that AD cases tend to overexpress 38A (10.45-fold on average with respect to the nADc individuals), thus correlating the synthesis of this ncRNA with the AD phenotype. At present, we are not able to determine with statistic significance whether there is a correlation between 38A increment and a specific clinical or pathological marker. To date, we can only confirm that there is a significant positive correlation between expression of 38A and AD and a negative correlation with non-AD cases. This general conclusion is reinforced by inspection of some cases that might represent exceptions: (a) controls with higher levels of 38A are case 5, characterized by severe chronic obstructive pulmonary disease and likely hypoxic cerebral damage, and case 963, who was a cognitively normal subject but with a high load of angiopathy and a Braak stage III amyloid status; (b) the AD patient with the lowest 38A level is case 124, who is a familial AD case carrying mutated PS1 and in which PS1 loss/gain of function might exert a predominant role in comparison to 38A (Fig. 7 A). The unaltered transcription of the PolIII-transcribed 5S rRNA in the aforementioned samples indicated that the phenomenon is caused by the specific overexpression of 38A rather than a general increase of PolIII activity (unpublished data).

Bottom Line: We found that IL1-α-dependent up-regulation of 38A, a small ribonucleic acid (RNA) polymerase III-transcribed RNA, drives the synthesis of an alternatively spliced form of the potassium channel-interacting protein (KCNIP4).Notably, synthesis of the variant KCNIP4 isoform is also detrimental to brain physiology, as it results in the concomitant blockade of the fast kinetics of potassium channels.This alternative splicing shift is observed at high frequency in tissue samples from Alzheimer's disease patients, suggesting that RNA polymerase III cogenes may be upstream determinants of alternative splicing that significantly contribute to homeostasis and pathogenesis in the brain.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Oncology, Biology, and Genetics, National Institute for Cancer Research, 16132 Genoa, Italy.

ABSTRACT
Alternative splicing generates protein isoforms that are conditionally or differentially expressed in specific tissues. The discovery of factors that control alternative splicing might clarify the molecular basis of biological and pathological processes. We found that IL1-α-dependent up-regulation of 38A, a small ribonucleic acid (RNA) polymerase III-transcribed RNA, drives the synthesis of an alternatively spliced form of the potassium channel-interacting protein (KCNIP4). The alternative KCNIP4 isoform cannot interact with the γ-secretase complex, resulting in modification of γ-secretase activity, amyloid precursor protein processing, and increased secretion of β-amyloid enriched in the more toxic Aβ x-42 species. Notably, synthesis of the variant KCNIP4 isoform is also detrimental to brain physiology, as it results in the concomitant blockade of the fast kinetics of potassium channels. This alternative splicing shift is observed at high frequency in tissue samples from Alzheimer's disease patients, suggesting that RNA polymerase III cogenes may be upstream determinants of alternative splicing that significantly contribute to homeostasis and pathogenesis in the brain.

Show MeSH
Related in: MedlinePlus