1. DEGs screening and co-DEGs identification between PAF and PsAF patients
The datasets GSE75092 and GSE113013 were both collected from GPL16956 platform, using Agilent-045997 Arraystar human LncRNA microarray. The GSE75092 dataset contained peripheral blood samples and coronary sinus blood samples from three PAF patients and peripheral blood samples from three controls[13]. While the GSE113013 dataset included atrial tissue samples from 5 PsAF patients (lasting more than 2 months) with valvular heart disease, which has been checked with the author Dr. Rao by email, and 5 controls (sinus rhythm patients with valvular heart disease). The information of the above two datasets is shown in Table 1.
Table 1
Basic information of datasets used in the study
GEO accession
|
GSE75092
|
GSE113013
|
Platform
|
GPL16956
|
GPL16956
|
Diseases
|
PAF
|
PsAF
|
Samples
|
Blood leukocytes
|
Atrial tissue
|
Number of subjects
|
3 patients + 3 controls
|
5 patients + 5 controls
|
PAF, paroxysmal atrial fibrillation; PsAF, persistent atrial fibrillation.
In GSE75092, a total of 127 DELncRNAs were screened between PAF patients and controls, of which 88 were upregulated and 39 were downregulated (Figure 1A-1B); and 321 DEmRNAs were screened, of which 155 were upregulated and 206 were downregulated (Figure 1C-1D).
In GSE113013, a total of 46 DELncRNAs were screened between PsAF patients and controls, of which 17 were upregulated and 29 were downregulated (Figure 2A-2B); and 64 DEmRNAs were screened, of which 22 were upregulated and 42 were downregulated (Figure 2C-2D).
8 co-DEGs were further identified in the overlap between the two datasets on Venn Diagram, which comprises 3 LncRNA and 5 mRNA (Figure 3 and Table 2). Of which 5 co-DEGs (RHOXF1, MC1R, LPL, AC009509.2, LINC02446) were consistently downregulated in both datasets, while 2 co-DEGs (TMEM44-AS1, SERPINB2) were upregulated in GSE75092 and downregulated in GSE113013, and 1 co-DEGs (MX1) was the opposite (Table 2).
Table 2
the co-DEGs between the two datasets
Gene symbol
|
GSE75092
|
GSE113013
|
Gene type
|
logFC
|
P.adjust
|
logFC
|
P.adjust
|
RHOXF1
|
-3.8949
|
0.0000
|
-1.3104
|
0.0361
|
mRNA
|
MC1R
|
-3.0642
|
0.0002
|
-3.4786
|
0.0000
|
mRNA
|
AC009509.2
|
-4.4094
|
0.0023
|
-5.3268
|
0.0002
|
LncRNA
|
LINC02446
|
-1.6999
|
0.0164
|
-1.4054
|
0.0029
|
LncRNA
|
LPL
|
-1.8276
|
0.0189
|
-1.9628
|
0.0128
|
mRNA
|
TMEM44-AS1
|
1.0474
|
0.0251
|
-1.1192
|
0.0377
|
LncRNA
|
SERPINB2
|
1.3521
|
0.0433
|
-1.7661
|
0.0299
|
mRNA
|
MX1
|
-2.4066
|
0.0482
|
2.9639
|
0.0348
|
mRNA
|
2. Enrichment analyses of DEGs between PAF and PsAF patients
The GO analyses of the above DEGs were performed on three critical categories, biological process (BP), molecular function (MF), and cellular component (CC). The results of GSE75092-DEGs were shown in Figure 4. In the BP category, the top 5 were mainly enriched in response to virus (P < 0.001), positive regulation of cytokine production (P < 0.001), defense response to virus (P < 0.001), nuclear transport (P = 0.004) and nucleocytoplasmic transport (P = 0.009). The CC category was mainly enriched in focal adhesion (P = 0.042) and cell-substrate junction (P = 0.042). The GO analysis of GSE113013-DEGs showed that no significant functions were enriched in any category.
KEGG analysis was performed for the GSE75092-DEGs, which were mainly enriched in hepatitis C (P = 0.003), influenza A (P = 0.005), NOD-like receptor signaling pathway (P = 0.008), Epstein-Barr virus infection (P = 0.014), measles (P = 0.016), and fluid shear stress and atherosclerosis (P = 0.016). The results were shown in Figure 5A. And the results of GSE113013 were mainly enriched in dopaminergic synapse (P = 0.003), antigen processing and presentation (P = 0.005), circadian entrainment (P = 0.008), melanogenesis (P = 0.014), vascular smooth muscle contraction (P = 0.016), and relaxin signaling pathway (P = 0.016). The results were shown in Figure 5B. There were two identical pathways, influenza A and adrenergic signaling in cardiomyocytes, in KEGG analysis of the DEGs between the two datasets.
The GO analysis was also performed on the 8 co-DEGs. It was found that the co-DEGs were mainly enriched in triglyceride biosynthetic process (P = 0.046), interleukin-12-mediated signaling pathway (P = 0.046), negative regulation of blood coagulation (P = 0.046), positive regulation of interleukin-1 beta production (P = 0.046), negative regulation of coagulation (P = 0.046) and positive regulation of interleukin-1 production (P = 0.047) for the BP category. For the CC category, they were mainly enriched in very-low-density lipoprotein particle (P = 0.018), triglyceride-rich plasma lipoprotein particle (P = 0.018), plasma lipoprotein particle (P = 0.022), lipoprotein particle (P = 0.022) and protein-lipid complex (P = 0.022). And for the MF category, it was found to be mainly enriched in phospholipase A1 activity (P = 0.035), apolipoprotein binding (P = 0.035), triglyceride lipase activity (P = 0.037), lipoprotein particle binding (P = 0.037) and protein-lipid complex binding (P = 0.037). KEGG analysis of the 8 co-DEGs was enriched in cholesterol metabolism (P = 0.024), glycerolipid metabolism (P = 0.030), peroxisome proliferators-activated receptor (PPAR) signaling pathway (P = 0.037), complement and coagulation cascades (P = 0.041) and melanogenesis (P = 0.049). The details are shown in Figure 6.
3. PPI network of the DEGs
The PPI analysis of the DEGs among two datasets was constructed using STRING database. Finally, an interaction network of GSE75092-DEGs with 292 nodes and 757 edges, and an interaction network of GSE113013-DEGs with 30 nodes and 32 edges were established in Cytoscape, as shown in Figure 7.
According to the node degree calculated by the cytoHubba, the top 10 hub genes of GSE75092-DEGs and GSE113013-DEGs were screened out and visualized in Figure 8, respectively. These top down-regulated hub nodes (proteins) called interferon-induced helicase C domain-containing protein 1 (IFIH1, degree = 30), ISG15 ubiquitin-like modifier (ISG15, degree = 29), interferon-induced GTP-binding protein Mx1 (MX1, degree = 27), interferon-induced protein with tetratricopeptide repeats 1 (IFIT1, degree = 25), interferon-induced protein with tetratricopeptide repeats 3 (IFIT3, degree = 21), 2'-5'-oligoadenylate synthase 2 (OAS2, degree = 21), interferon alpha inducible protein 6 (IFI6, degree = 21), interferon-induced protein with tetratricopeptide repeats 2 (IFIT2, degree = 21), 2'-5'-oligoadenylate synthase 3 (OAS3, degree = 21) and Radical S-adenosyl methionine domain-containing protein 2 (RSAD2, degree = 21) were regarded as hub genes in relation to GSE75092-DEGs (Figure 8A). Moreover, these top down-regulated hub nodes (proteins) called cathepsin G (CTSG, degree = 4), cystatin-F (CST7, degree = 4), granzyme K (GZMK, degree = 4), granzyme A (GZMA, degree = 4), killer cell lectin-like receptor subfamily K (KLRK1, degree = 4), protein S100-A12 (S100A12, degree = 4), calmodulin 2 (CALM2, degree = 3), and granzyme H (GZMH, degree = 3), and the top up-regulated hub node (protein) called adenylate cyclase type 2 (ADCY2, degree = 3) and guanine nucleotide-binding protein G(o) subunit alpha (GNAO1, degree = 3) were considered as top 10 hub genes related to GSE113013-DEGs (Figure 8B).