TLR4 downregulation by the RNA-binding protein PUM1 alleviates cellular aging and osteoarthritis

Abstract

Dysfunction of mRNA or RNA-binding proteins (RBPs) causes cellular aging and age-related degenerative diseases; however, information regarding the mechanism through which RBP-mediated posttranscriptional regulation affects cellular aging and related disease processes is limited. In this study, PUM1 was found to be associated with the self-renewal capacity and aging process of human mesenchymal stem cells (MSC). PUM1 interacted with the 3'-untranslated region of Toll-like receptor 4 (TLR4) to suppress TLR4 mRNA translation and regulate the activity of nuclear factor-κB (NF-κB), a master regulator of the aging process in MSCs. PUM1 overexpression protected MSCs against H 2 O 2 -induced cellular senescence by suppressing TLR4-mediated NF-κB activity. TLR4mediated NF-κB activation is a key regulator in osteoarthritis (OA) pathogenesis. PUM1 overexpression enhanced the chondrogenic potential of MSCs even under the influence of inflammation-inducing factors, such as lipopolysaccharide (LPS) or interleukin-1β (IL-1β), whereas the chondrogenic potential was reduced following the PUM1 knockdown-mediated TLR4 activation. PUM1 levels decreased under inflammatory conditions in vitro and during OA progression in human and mouse disease models. PUM1 knockdown in human chondrocytes promoted chondrogenic phenotype loss, whereas PUM1 overexpression protected the cells from inflammation-mediated disruption of the chondrogenic phenotype. Gene therapy using a lentiviral vector encoding mouse PUM1 showed promise in preserving articular cartilage integrity in OA mouse models. In conclusion, PUM1 is a novel suppressor of MSC aging, and the PUM1-TLR4 regulatory axis represents a potential therapeutic target for OA.

RUNX2 stabilization by long non-coding RNAs contributes to hypertrophic changes in human chondrocytes

“…RNA-IP was described previously 64 . Briefly, RNA-IP was performed to determine the potential interactions between RUNX2 protein and the lncRNAs selected in this study.…”

“…Information of the vector used in this study is shown in Supplementary Figure S1 . PB-control or PB-LINC02035 was transfected with TC28a2 cells using electroporation with the neon transfection system (Cat no, MPK5000; Invitrogen), and the electroporation method was described previously 64 . Briefly, TC28a2 cells were prepared at approximately 1 × 10 6 cells per trial, suspended in 90 µL of Transfection Resuspension Buffer, and then mixed with 6 μg of plasmid DNA in 10 µL volume.…”

Deubiquitinating Enzyme USP7 Is Required for Self-Renewal and Multipotency of Human Bone Marrow-Derived Mesenchymal Stromal Cells

“…A CFU-F assay was performed as previously described [ 42 ]. In brief, hBMSCs were seeded in 10 cm 2 dishes in amounts of 1 × 10 3 cells/dish.…”

RNA binding proteins in osteoarthritis

“…Deng et al reported that NCL promotes articular chondrocyte proliferation via the MAPK/Erk1/2 pathway ( Deng et al, 2020 ). In addition, Lee et al reported that PUM1 interacted with the 3′-UTR of TLR4 to suppress its mRNA translation, and PUM1 overexpression protected the chondrocytes from inflammation-mediated disruption of the chondrogenic phenotype ( Yoon et al, 2022 ).…”

“…Second, RBPs also regulated the cell senescence, autophagy, apoptosis, and inflammatory response of mesenchymal stem cells, chondrocytes, and synovial fibroblasts. Researchers reported that PUM1 binds with TLR4 mRNA and suppressed its expression, and then, it inhibited cellular aging of MSCs and OA progression ( Yoon et al, 2022 ). Fu and others reported that TAF15 was upregulated in cartilage tissues from osteoarthritis patient.…”