MRG-201

Osteoclasts are the cells primarily responsible for inflammation‐induced bone loss, as is particularly seen in rheumatoid arthritis. Increasing evidence suggests that osteoclasts formed under homeostatic versus inflammatory conditions may differ in phenotype. While microRNA‐29‐3p family members (miR‐29a‐3p, miR‐29b‐3p, miR‐29c‐3p) promote the function of RANKL‐induced osteoclasts, the role of miR‐29‐3p during inflammatory TNF‐α‐induced osteoclastogenesis is unknown. We used bulk RNA‐seq, histology, qRT‐PCR, reporter assays, and western blot analysis to examine bone marrow monocytic cell cultures and tissue from male mice in which the function of miR‐29‐3p family members was decreased by expression of a miR‐29‐3p tough decoy (TuD) competitive inhibitor in the myeloid lineage (LysM‐cre). We found that RANKL‐treated monocytic cells expressing the miR‐29‐3p TuD developed a hypercytokinemia/proinflammatory gene expression profile in vitro, which is associated with macrophages. These data support the concept that miR‐29‐3p suppresses macrophage lineage commitment and may have anti‐inflammatory effects. In correlation, when miR‐29‐3p activity was decreased, TNF‐α‐induced osteoclast formation was accentuated in an in vivo model of localized osteolysis and in a cell‐autonomous manner in vitro. Further, miR‐29‐3p targets mouse TNF receptor 1 (TNFR1/Tnfrsf1a), an evolutionarily conserved regulatory mechanism, which likely contributes to the increased TNF‐α signaling sensitivity observed in the miR‐29‐3p decoy cells. Whereas our previous studies demonstrated that the miR‐29‐3p family promotes RANKL‐induced bone resorption, the present work shows that miR‐29‐3p dampens TNF‐α‐induced osteoclastogenesis, indicating that miR‐29‐3p has pleiotropic effects in bone homeostasis and inflammatory osteolysis. Our data supports the concept that the knockdown of miR‐29‐3p activity could prime myeloid cells to respond to an inflammatory challenge and potentially shift lineage commitment toward macrophage, making the miR‐29‐3p family a potential therapeutic target for modulating inflammatory response.

MicroRNA-29a (miR-29a) has been suggested to serve a potential protective function against Parkinson's disease (PD); however, the exact molecular mechanisms remain elusive. This study explored the protective role of miR-29a in a cellular model of PD using SH-SY5Y cell lines through iTRAQ-based quantitative proteomic and biochemistry analysis. The findings showed that using a miR-29a mimic in SH-SY5Y cells treated with 1-methyl-4-phenylpyridinium (MPP+) significantly decreased cell death and increased mitochondrial membrane potential. It also reduced mitochondrial reactive oxygen species (ROS) and the production of α-synuclein. Subsequent heatmap analysis using iTRAQ-based quantitative proteomics revealed remarkably contrasting protein expression profiles for 882 genes when comparing the groups treated with miR-29a mimic plus MPP + against the control group treated solely with MPP+. The KEGG pathway analysis of these 882 genes indicated the substantial role of miR-29a in the PD pathway (P = 1.58x10^-5) and highlighted its function in mitochondrial genes. Furthermore, treatment with a miR-29a mimic in SH-SY5Y cells reduced the levels of GSK-3β, phosphorylated GSK-3β, and cleaved caspase-7 following exposure to MPP+. The miR-29a mimic also upregulated the expressions of α-synuclein clearance proteins FYCO1 and Rab7 in this cellular PD model, thereby inhibiting the production of α-synuclein. Luciferase activity analysis confirmed the specific binding of miR-29a to the 3' untranslated region (3'UTR) of GSK-3β, leading to its repression. Our findings demonstrated miR-29a's neuroprotective role in mitochondrial function and highlighted its potential to inhibit ROS and α-synuclein production, offering possible therapeutic avenues for PD treatment.