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Prediction of protein aggregation on key proteins involved in ischemic stroke
⁎Corresponding author. alaguraj.veluchamy@kaust.edu.sa (Alaguraj Veluchamy)
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Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Peer review under responsibility of King Saud University.
Abstract
Stroke is a genetic condition comprising multiple subtypes and arising from both genic and other multi factors. Genetic basis of stroke is well established through several studies. Advances in integrating sequencing methods and Genome-wide association studies have shown that genetics of stroke is manifested in several genic disorders. Many of the neurodegenerative disorders show aggravated protein aggregation through amyloid formation. Through the protein aggregation prediction, we observed a higher protein disorder in 46 stroke-associated proteins. Also, we observed a large number of aggregation residues distributed as a pattern in multiple regions of these candidate proteins. Overall, we present a study showing that there is a possible interrelationship between protein aggregation and stroke.
Keywords
Genetic disorder
Ischemic stroke
Protein aggregation
Gene ontology
KEGG pathway
1 Introduction
Stroke is a complex heterogenous condition that is one of the major causes of ailment and death in the world. Characterizing stroke involves classification into subtypes. Several classification systems have been proposed to differentiate subtypes of stroke and distinguish between ischemic and hemorrhagic stroke, subarachnoid hemorrhage, cerebral venous thrombosis, and spinal cord stroke (Amarenco et al., 2009). Studies such as the association of monozygotic twins to stroke provide the evidence of implication of genetic factors in stroke pathophysiology. Next generation sequencing (NGS), genome-wide association studies (GWAS) provided evidence that stroke is both a monogenic and a polygenic disorder. Both above classification systems and genetic studies are vital in grouping patients for therapeutic purposes.
Whole-genome sequencing studies have resulted identifying novel variants associated with stroke subtypes. A genome-wide association study through Trans-Omics for Precision Medicine (TOPMed) Program identified 5 novel loci associated with subtypes of stroke in a multi-ancestry population (Hu et al., 2022). Besides this, MEGASTROKE consortium have performed genotyping and GWAS studies that resulted in identification of stroke risk variants such as NKX2-5, ANK2, LRCH1, REEP3, JAZF1(de Vries et al., 2019; Malik et al., 2018).
Although multiple stroke specific risk loci are detected, functional characterization of these loci are challenging as these variants fall mostly on non-coding regions of the genome. Hence recent approaches use data from gene expression, DNA methylation to establish a causal relationship to stroke susceptible genes. Analysis of candidate genes involved in ischemic stroke resulted in identification of at least five susceptibility genes such as factor V Leiden Gln506, ACE I/D, MTHFR C677T, prothrombin G20210A, PAI-1 5G (Bentley et al., 2010).
Emerging evidence shows that protein aggregates formed in Ischemic stroke. Misfolded proteins tend to form fibers of aggregates (Hu et al., 2001). In particular ischemic stroke (Luo et al., 2013); stroke and aggregation (Zhang et al., 2020). Protein aggregates are found to be form deposits in degenerate cells and are involved in cellular toxicity (Tutar et al., 2013). Several neurological disorders such as Parkinson’s Disease (PD), Huntington’s disease (HD), prion diseases, Amyotrophic lateral sclerosis (ALS) are associated with the formation of protein aggregate (Pedersen & Heegaard, 2013). Aβ-peptide (1–40/1–42) forms amyloid plaque in regions such as cortex, hippocampus and forebrain. Proteins such as Tau, α-synuclein, Ataxins, superoxide dismutase (SOD1) and RNA binding proteins TDP43, FUS, TAF15 are found to form lewy bodies, intranuclear inclusion, axonal spheroids and cytoplasmic aggregates (Kumar et al., 2016).
Efforts on analysis of protein aggregation and characterization shown significant improvement in the development of protein aggregation prediction methods. More than 20 different computational algorithms are available now for the prediction of protein aggregation based on amino acid sequences (Santos et al., 2020). Tools such as TANGO, PASTA2.0, AGGRESCAN uses either protein features or experimental data to predict protein aggregation (Conchillo-Solé et al., 2007; de Groot et al., 2005; Walsh et al., 2014). Taking advantage of the available methods of protein aggregation prediction and sequences available on the stroke dataset, here we explored the connection or common theme between the above stroke and amyloid formation.
2 Methods
2.1 Dataset of candidate genes associated with disorders related to stroke
We performed text mining and sequence database search through pubmed to obtain a base dataset of genes associated with Ischemic stroke. As stroke is linked to both monogenic and polygenic disorders, we obtained list of genes reported earlier (Ekkert et al., 2022). Each of these genes in the dataset have certain impact on stroke pathogenesis. Mutiple literature and database search resulted in a dataset of 46 genes linked to risk of stroke.
2.2 Functional annotation of genes linked to stroke disorders
Curated canonical protein sequences are obtained from UniProtKB/Swiss-Prot protein sequence database (The UniProt Consortium, 2021). Only full-length protein sequences are used for each of these genes. Alternative sequences for each ids are avoided to remove redundancy and only unique sequences are further analyzed. For functional annotation of gene list, DAVID knowledgebase which is a webserver for bioinformatics resource providing functional enrichment analysis is utilized (Sherman et al., 2022).
2.3 Prediction of protein aggregation in stroke disorder associated protein sequences
To evaluate the tendency of proteins associated with stroke to form protein aggregate, we performed analysis whether these sequences forms β-sheet enriched secondary structure conformation. Using a pairwise energy potential, intrinsic disorder and secondary structure, protein aggregation calculation for the candidate protein sequences were performed in PASTA2.0 webserver (Walsh et al., 2014).
2.4 Amyloidogenic region in the protein sequences
Smaller fragments of regions in the protein sequences responsible for the amylodogenesis (Ivanova et al., 2004). These regions are composed of aminoacids which are unique and distinct from other non-aggregating regions or peptides. Using expected contact of the residues in the protein sequences, amyloidogenic regions are predicted (Garbuzynskiy et al., 2010).
3 Results
We have shown here that the protein aggregation might occur among the candidate proteins involved in stroke associated disorders. The pathophysiology between the neurodegenerative disorders and protein aggregation are shown to be shared. Our approach has shown that there could be a significant overlap between the pathophysiology of amyloid formation and ischemic stroke.
3.1 Genes involved in monogenic and polygenic disorders associated with stroke
Around 46 genes related to stroke associated disorders are retrieved from different databases. These genes are found to have around 687 splice variants in the UniprotKB. We used full length canonical protein sequences for further analysis. Annotation of genes retrieved through DAVID shows that most genes are related to signaling function including receptors (Table1). Multiple candidate genes functions have stroke phenotypic manifestation.
SI
From
Species
David Gene Name
1
NOTCH3
Homo sapiens
notch receptor 3(NOTCH3)
2
FOXC1
Homo sapiens
forkhead box C1(FOXC1)
3
CASZ1
Homo sapiens
castor zinc finger 1(CASZ1)
4
WNT2B
Homo sapiens
Wnt family member 2B(WNT2B)
5
LINC01492
Homo sapiens
long intergenic non-protein coding RNA 1492(LINC01492)
6
HTRA1
Homo sapiens
HtrA serine peptidase 1(HTRA1)
7
ADCY2
Homo sapiens
adenylate cyclase 2(ADCY2)
8
PRPF8
Homo sapiens
pre-mRNA processing factor 8(PRPF8)
9
HDAC9
Homo sapiens
histone deacetylase 9(HDAC9)
10
ABO
Homo sapiens
ABO, alpha 1–3-N-acetylgalactosaminyltransferase and alpha 1–3-galactosyltransferase(ABO)
11
ZCCHC14
Homo sapiens
zinc finger CCHC-type containing 14(ZCCHC14)
12
EDNRA
Homo sapiens
endothelin receptor type A(EDNRA)
13
SH3PXD2A
Homo sapiens
SH3 and PX domains 2A(SH3PXD2A)
14
CBS
Homo sapiens
cystathionine beta-synthase(CBS)
15
PITX2
Homo sapiens
paired like homeodomain 2(PITX2)
16
ZNF566
Homo sapiens
zinc finger protein 566(ZNF566)
17
NKX2-5
Homo sapiens
NK2 homeobox 5(NKX2-5)
18
SH2B3
Homo sapiens
SH2B adaptor protein 3(SH2B3)
19
HABP2
Homo sapiens
hyaluronan binding protein 2(HABP2)
20
RGS7
Homo sapiens
regulator of G protein signaling 7(RGS7)
21
FGA
Homo sapiens
fibrinogen alpha chain(FGA)
22
ZFHX3
Homo sapiens
zinc finger homeobox 3(ZFHX3)
23
FOXF2
Homo sapiens
forkhead box F2(FOXF2)
24
TREX1
Homo sapiens
three prime repair exonuclease 1(TREX1)
25
ABCC6
Homo sapiens
ATP binding cassette subfamily C member 6(ABCC6)
26
ANK2
Homo sapiens
ankyrin 2(ANK2)
27
PDZK1IP1
Homo sapiens
PDZK1 interacting protein 1(PDZK1IP1)
28
TBX3
Homo sapiens
T-box transcription factor 3(TBX3)
29
MMP12
Homo sapiens
matrix metallopeptidase 12(MMP12)
30
COL3A1
Homo sapiens
collagen type III alpha 1 chain(COL3A1)
31
LRCH1
Homo sapiens
leucine rich repeats and calponin homology domain containing 1(LRCH1)
32
CDK6
Homo sapiens
cyclin dependent kinase 6(CDK6)
33
GAL
Homo sapiens
galanin and GMAP prepropeptide(GAL)
34
COL4A2
Homo sapiens
collagen type IV alpha 2 chain(COL4A2)
35
COL4A1
Homo sapiens
collagen type IV alpha 1 chain(COL4A1)
36
PDE3A
Homo sapiens
phosphodiesterase 3A(PDE3A)
37
KCNK3
Homo sapiens
potassium two pore domain channel subfamily K member 3(KCNK3)
38
LOC100505841
Homo sapiens
zinc finger protein 474-like(LOC100505841)
39
FBN1
Homo sapiens
fibrillin 1(FBN1)
42
ILF3
Homo sapiens
interleukin enhancer binding factor 3(ILF3)
43
CDKN2A
Homo sapiens
cyclin dependent kinase inhibitor 2A(CDKN2A)
44
ZNF318
Homo sapiens
zinc finger protein 318(ZNF318)
45
FURIN
Homo sapiens
furin, paired basic amino acid cleaving enzyme(FURIN)
46
TM4SF4
Homo sapiens
transmembrane 4 L six family member 4(TM4SF4)
47
PMF1
Homo sapiens
polyamine modulated factor 1(PMF1)
48
SMARCA4
Homo sapiens
SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4(SMARCA4)
3.2 Prediction of protein aggregation
Formation of amyloid aggregates is implicated in several neurodegenerative disorders. We use protein disorder as a scale for predicting protein aggregation. Propensity of aggregation remains relatively similar across multiple methods for candidate stroke related genes (Fig. 1). We further used PASTA2.0 to determine the percentage of protein disorder, number of amyloid within the protein sequence, percentage of α-helix, percentage of β-strand etc. Percentage disorder of proteins vary ranging from 1 to upto 80 for stroke associated genes. For a random dataset of non-stroke related genes this range from 1.5 to 63. Median value differs significantly between these two groups of proteins (Fig. 2). Statistical test (t-test) using R between the above two groups of proteins was performed. This test reveals a significantly lower p-value (p-value = 0.007744). This is highly significant and percentage disorder is higher for stroke associated genes.Consensus methods predicting same amyloid regions.
Boxplot showing the differences in the disorder among two groups of proteins.
3.3 Residue based prediction of aggregation specific protein region
Each protein sequences are predicted to have atleast 20 poteintial amyloid forming short amino acid sequence pattern (Table 2). Consensus pattern derived from multiple amyloid predicting tools such as TANGO, AGGRESCAN, WALTZ through FoldAmyloid shows that these patterns are detected in all methods (Fig. 1). For example, in protein WNTB-2B, these aggregation forming residues are distributed in 14 different sites (Fig. 3). Most of these patterns are 4–14 aminoacid length (Fig. 4).
Protein name (from fasta header)
Length
# Amyloids
Best energy
% disorder
% α-helix
% β-strand
% coil
spQ08462
1091
20
−39.221871
4.216
64.25
8.07
27.68
spO95255
1503
20
−19.941325
8.715
59.41
6.25
34.33
spQ9Y2L9
728
20
−19.362124
27.33
42.58
10.03
47.39
spP09958
794
20
−18.84564
18.26
15.49
25.06
59.45
spQ13113
114
20
−17.268009
16.66
48.25
8.77
42.98
spO14649
394
20
−17.165792
28.17
65.48
2.79
31.73
spP25101
427
20
−16.917126
7.259
64.64
6.32
29.04
spQ9UM47
2321
20
−15.802264
13.09
17.36
16.59
66.05
spP48230
202
20
−15.752635
7.92
54.46
2.97
42.57
spQ6P2Q9
2335
20
−14.995744
1.498
46.55
13.28
40.17
spQ14432
1141
20
−14.680867
33.74
41.89
7.01
51.1
spP16442
354
20
−14.397722
3.672
33.9
16.95
49.15
spP02671
866
20
−10.907301
35.33
16.17
24.02
59.82
spQ01484
3957
20
−10.281311
42.91
26.38
14.43
59.19
spP35520
551
20
−10.195829
15.06
37.75
14.7
47.55
spQ5TCZ1
1133
20
−9.781373
45.18
11.92
21.27
66.81
spQ15911
3703
20
−9.775551
52.17
32.19
8.37
59.44
spQ93097
391
20
−9.619822
10.48
45.78
14.07
40.15
spQ8N726
132
20
−9.546539
66.66
11.36
14.39
74.24
spQ12906
894
20
−9.535643
47.2
28.75
10.18
61.07
spQ00534
326
20
−9.230796
13.49
43.86
16.87
39.26
spQ92743
480
20
−8.959704
13.33
18.96
30.83
50.21
spQ9UQQ2
575
20
−8.630576
45.04
24.35
14.61
61.04
spQ12947
444
20
−8.290021
52.02
22.52
3.83
73.65
spP51532
1647
20
−8.254159
50.15
46.63
5.22
48.15
spQ9UKV0
1011
20
−8.19617
29.57
40.26
8.51
51.24
spP35555
2871
20
−7.913752
3.065
4.25
31.8
63.95
spP39900
470
20
−7.626874
4.042
23.83
23.83
52.34
spP49802
495
11
−7.622278
11.11
52.93
2.42
44.65
spP02462
1669
20
−7.454205
83.1
2.64
8.63
88.74
spQ14520
560
20
−7.387258
6.607
14.46
26.43
59.11
spQ9NSU2
314
20
−6.854083
27.7
40.45
6.69
52.87
spP08572
1712
20
−6.646477
62.44
2.69
9.35
87.97
spO15119
743
9
−6.556453
32.03
28.4
11.84
59.76
spQ12948
553
6
−6.366574
65.82
22.78
6.69
70.52
spQ5VUA4
2279
11
−6.276438
50.89
27.29
10.79
61.91
spQ969W8
418
1
−5.915617
3.588
22.73
18.66
58.61
spP42771
156
7
−5.761273
28.2
50
0
50
spQ86V15
1759
20
−5.735543
44.11
19.56
17.45
62.99
spQ8N6F7
178
4
−5.629332
28.08
21.91
13.48
64.61
spP22466
123
3
−5.60644
80.48
52.03
0
47.97
spQ99697
317
3
−5.452123
34.7
37.54
3.79
58.68
spQ8WYQ9
949
1
−5.372969
50.36
18.02
16.97
65.02
spP02461
1466
2
−5.361421
77.96
3.96
6.48
89.56
spQ6P1K2
205
1
−5.021246
22.43
76.59
0
23.41
spP52952
324
0
−4.668274
15.12
30.56
11.11
58.33
Contact frequency predicted for different residues across the protein sequence is shown here.
Amyloidogenic residues predicted for human Wnt-2b protein.
4 Discussion
Analysis of protein aggregation from 46 protein sequences implicated in stroke manifestation shows that large number of proteins form amyloids with varying degree of protein disorder. The role of protein aggregation and amyloid formation in the neurodegenerative diseases are well established (Pedersen & Heegaard, 2013; Tutar et al., 2013). Also, earlier studies have shown that there is higher levels or induction of protein aggregation after cerebral Ischemia (Wu & Du, 2021). Compared to the random datasets of proteins from UniprotKB, these proteins are found to have higher percentage of protein disorder. This could arise from the β-strand composition of these sequences. Furthermore, structural variation including SNP and small indels in these genes could possibly contribute to the amyloid formation. Our work contributes to the evidence that protein aggregation could be implicated in stroke disorder. Further research following our findings would improve our knowledge on the molecular level overlap between these two related process and disorder. More experimental evidences are needed for implicating the above listed genes (their products) in the protein aggregation. Establishing mouse models for stroke and investigating the aggregation through electron microscopy, laser-scanning confocal microscopy, and Western blotting could help further.
5 Conclusion
In the present study, we analyzed the aggregation properties of stroke related proteins. We selected a set of stroke-associated candidate proteins and a set of random control dataset. Overall, we observed that most proteins associated with stroke have higher protein disorder compared to a random dataset of protein sequences. These amyloids forming aggregating residues are distributed anywhere between the N-terminal and C-terminal part of the sequence of these candidate proteins. We found the contact frequency profile value of multiple residues are higher than average expected value and is part of disordered region related to protein conformation. Our study suggests that there is an overlap in pathophysiology of protein aggregation, neurological disorders and stroke related disorders.
Acknowledgment
The authors extend their appreciations to the deputyship for Research & Innovation, Ministry of Education in Saudi Arabia for funding this research work through the project number (lFP-2020-38).
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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Appendix A
Supplementary material
Supplementary data to this article can be found online at https://doi.org/10.1016/j.jksus.2022.102474.
Appendix A
Supplementary material
The following are the Supplementary data to this article: