Prior research has shed light on RGS2's involvement in neurodegenerative diseases and key signaling pathways. Dusonchet and colleagues demonstrated that RGS2 affects both GTPase and kinase activities of LRRK2, significantly influencing the length of neuronal processes. This role of RGS2 is vital for protecting against damage from the prevalent LRRK2 mutation, G2019S, suggesting a novel action mechanism for GAP proteins, distinct from their known GTPase activity modulation. Such findings position RGS2 as a promising candidate for therapeutic intervention in Parkinson's disease (PD), particularly for conditions related to LRRK2 mutations (48). As a member of the RGS protein family, RGS2 interacts with Gα components of heterotrimeric G proteins, specifically targeting Gαq and Gαi subunits to slow their GTP to GDP hydrolysis, thereby reducing signal transduction from G-protein-coupled receptors (GPCRs) and playing a crucial role in synaptic plasticity (49). Moreover, RGS2 directly interacts with adenylyl cyclases, decreasing cyclic AMP (cAMP) production, and influencing GPCR-mediated Akt signaling pathways, highlighting its regulatory impact (50). Increased RGS2 expression intensifies neurodegeneration caused by mutant Huntingtin (mHtt), with preliminary data suggesting a link to the Erk/MAP kinase signaling pathway. However, the exact mechanisms remain to be fully elucidated (51). This study further supports the hypothesis that RGS2 upregulation may elevate the risk of neurodegenerative diseases, reinforcing its potential as a therapeutic target (52).
In our research, we found that RGS2 and its interacting network play a significant role in modulating the NF-κB signaling pathway. The NF-κB family of transcription factors is crucial for regulating genes involved in vital cellular functions such as survival, cell death, inflammation, growth, and differentiation (53). Within the nervous system, NF-κB is uniquely active at high levels in neurons, highlighting its essential role in overseeing specific functions in the central nervous system (CNS). It is a critical regulator of neuronal architecture and profoundly influences neuronal plasticity, which in turn impacts learning, memory, and behavior. Additionally, NF-κB provides neurons with protection against damage from excitotoxicity, oxidative stress, and ischemia. It also contributes to the inflammatory response and cell death in cases of brain injury and stroke. In contrast, glial cells show no inherent NF-κB activity under unstressed conditions, suggesting that NF-κB activation in these cells is mainly triggered by stress or pathological conditions (54).
Our research findings demonstrate that RGS2 interacts with the proteins BCL10, TNFAIP3, and TNFSF13B, which are key regulators of the NF-κB signaling pathway. The activation of NF-κB, a crucial process following T-cell receptor (TCR) stimulation, depends on assembling the CARMA1–Bcl-10–MALT1 (CBM) complex at the cell membrane, a step facilitated by protein kinase Cθ (PKCθ) (55). This assembly is essential for NF-κB to be subsequently activated by the IKK complex. The critical nature of the CBM complex in this pathway is highlighted by studies on mice lacking CARMA1, Bcl-10, or MALT1, which show reduced NF-κB activation, lower Th1 cytokine production, and decreased T-cell proliferation following TCR activation (56–58). Additionally, genome-wide association studies (GWASs) have identified new genetic loci linked to MS susceptibility in the TNFRSF1A and MALT1 genes, encoding TNF-R1 and MALT1, respectively. These studies have also confirmed TNFAIP3 as a risk gene for MS, underscoring its significance in MS pathogenesis.
Based on previous studies, the NCK1-DT is an important regulatory factor for various cancer types, including prostate cancer, lung cancer, and gastric cancer (59). Also, Xie et al. revealed that ASH1L-AS1 has a significant regulatory role in gastric cancer development via modulation of the “RAS signaling pathway” (60). However, there was no previous study about the possible roles of NCK1-DT and ASH1L-AS1 in MS development. In this study, for the first time, we evaluated the expression level of two mentioned lncRNAs in MS patients and revealed the up-regulation of NCK1-DT and ASH1L-AS1 in MS samples. Furthermore, for the first time, we evaluated the interaction of NCK1-DT and ASH1L-AS1 with mRNA RGS2. Based on our experimental evaluations, NCK1-DT and ASH1L-AS1 could be considered two potential novel diagnostic biomarkers of MS. RGS2, NCK1-DT, and ASH1L-AS1 as three MS biomarkers have multiple direct and indirect interactions.
One of the most important parts of our investigation is the miRNA interaction analysis. Based on our bioinformatics analyses, miR-4638-3p might have a significant suppressor role in the expression level of mRNA RGS2 via direct interaction with the 3’UTR region of this mRNA. Low expression of miR-4638-3p could be one reason for up-regulation of RGS2 in MS patients. Also, there was no previous study about the possible role of miR-4538-3p in MS progression. However, there were two studies about the potential roles of miR-4638-3p in the development of breast cancer. Akshaya et al. 2022 revealed that miR-4638-3p influences the activation of transcription factor-3 induced by transforming growth factor-β1, affecting cell growth, invasion, and programmed cell death in human breast cancer cells (61). Another study of that research group revealed that miR-4638-3p has a significant role in the bone metastasis of breast cancer cells (62). Based on our analyses, miR-4525 is one of the potential regulatory non-coding RNAs for the changes in the expression level of RGS2 and ASH1L-AS1. Based on ceRNA theory, when two RNA molecules possess identical microRNA response elements (MREs), they may vie for a common set of miRNAs. Consequently, if the expression of a ceRNA increases, it sequesters more miRNAs (a process known as miRNA sponging), reducing the number of miRNAs available to bind to the mRNA sharing the same MRE. As a result, this leads to the derepression of the specific mRNA (63, 64). In this case, RGS2 and lncRNA ASH1L-AS1 share the same MRE for miR-4525, and up-regulation of lncRNA ASH1L-AS1 leads to the high expression of RGS2. So, ASH1L-AS1 might affect the expression level of RGS2 directly and indirectly. Also, ASH1L-AS1 and NCK1-DT have the same indirect interaction via binding affinity to miR-365a-3p and miR-365b-3p with the same mechanism. There were no previous studies about the potential roles of mentioned lncRNAs and miRNAs in MS. However, due to our limitations, we could not validate the direct interactions by experimental approach. So, it is highly recommended that the interaction of NCK1-DT, ASH1L-AS1, miR-4638-3p, and miR-4525 with RGS2 be evaluated using experimental methods (e.g. Luciferase assay or RIP).