ARTICLE | doi:10.20944/preprints202102.0602.v1
Online: 26 February 2021 (09:38:28 CET)
Knee Osteoarthritis (KOA) is a chronic disease characterized by progressive disability and joint pain. Meniscus chondrocytes apoptosis is the main cause of reduced chondrocyte number and self-repair function. The purpose of this study was to investigate the role of miR-27b-3p in KOA.In this study, we found that the expression of miR-27b-3p was downregulated in cultured IL-1β treated chondrocyte and cartilage tissues in KOA. KOA overexpression evidently reduced IL-1β induced chondrocyte apoptosis and caspase-3 and caspase-9 expression.The upregulated iNOS and COX-2 mRNA and proteins expression was also inhibited by miR-27b-3p mimics. The expression of nitric oxide, PGE2, TNF-α and IL-6 was also inhibited by miR-27b-3p mimics. The target gene of miR-27b-3p was confirmed to be BDNF. TrkB/CREB pathway was proved to be the downstream pathway of miR-27b-3p/BDNF axis.The apoptotic cell percentage and nitric oxide, PGE2, TNF-α and IL-6 expression was induced by BDNF+IL-1β. This induction was inhibited by miR-27b-3p mimics. The cartilage tissues stained with safranin O results showed miR-27b-3p greatly decreased KOA induced cartilage degradation. The expression of BDNF、TrkB and p-CREB was inhibited by len-miR-27b-3p. MiR-27b-3p also reduced the expression of TNF-α、IL-6 and Bax, and increased Bcl-2 expression. These results indicated miR-27b-3p could applied to inhibit the development of KOA and miR-27b-3p/BDNF/TrkB/CREB pathway could serve as novel treatment target to handle KOA.
ARTICLE | doi:10.20944/preprints201904.0277.v1
Subject: Life Sciences, Molecular Biology Keywords: CREB; cryotherapy; gene expression; icing; mitochondria; Pgc-1α; transcription
Online: 25 April 2019 (08:07:44 CEST)
Local cryotherapy is widely used as a treatment for sports-related skeletal muscle injury. However, its molecular mechanisms are unknown. To clarify these mechanisms, in this study, we applied one to three 15-min cold stimulations at 4 °C to various cell lines (in vitro), the tibialis anterior (TA) muscle (ex vivo), and mouse limbs (in vivo). In the in vitro assay, cAMP response element-binding protein 1 (CREB1) was markedly phosphorylated (as pCREB1) and CREB-binding protein (CBP) was recruited to pCREB-1 in response to two or three cold stimulations. In a reporter assay with the cAMP-responsive element, the signals significantly increased after two to three cold stimulations at 4 °C. In the ex vivo study, CREB-targeting genes were significantly upregulated following two or three cold stimulations. The in vivo experiment disclosed that cold stimulation of a mouse limb for 9 days significantly increased mitochondrial DNA copy number and upregulated genes such as Pgc-1α involved in mitochondrial biogenesis. The foregoing results suggest that local cryotherapy increases CREB transcription and upregulates CREB-targeting genes in a manner dependent on cold stimulation frequency and duration. This information may serve as an impetus for further investigations into local cryotherapy as a treatment for sports-related skeletal muscle trauma.
ARTICLE | doi:10.20944/preprints202104.0565.v1
Subject: Life Sciences, Biochemistry Keywords: induced cardiomyocyte; epigenetic reprogramming; heart regeneration; cell plasticity; transdifferentiation; CREB-CBP
Online: 21 April 2021 (09:39:05 CEST)
Direct cardiac reprogramming of fibroblasts into induced cardiomyocytes (iCMs) is a promising approach but remains a challenging technology of regenerative medicine for damaged myocardium. Efforts have been focused on improving the efficiency by understanding fundamental mechanisms. One of the major challenges is that the plasticity of cultured fibroblast varies batch to batch with unknown mechanisms. Here, we noticed that a portion of in vitro cultured fibroblasts have been activated to differentiate into myofibroblasts, marked by the expression of αSMA, even in the primary cell culture of tissues. Both forskolin, which activates adenylyl cyclase and increases cAMP concentration, and TGFbeta inhibitor SB431542 can efficiently suppress myofibroblast differentiation of cultured fibroblasts. However, SB431542 improved but forskolin blocked iCM reprogramming of fibroblasts that were infected with retroviruses of Gata4, Mef2c and Tbx5 (GMT). Moreover, inhibitors of cAMP downstream signaling pathways, PKA or CREB-CBP, significantly improved the efficiency of iCM reprogramming. Consistently, inhibition of p38/MAPK, another upstream regulator of CREB-CBP, also improved reprogramming efficiency. We then investigated if inhibition of these signaling pathways in primary cultured fibroblast could improve their plasticity for reprogramming, and found that preconditioning of cultured fibroblasts with CREB-CBP inhibitor significantly improved the cellular plasticity of fibroblasts to be reprogrammed, yielding ~2-fold amount of reprogrammed iCMs compared to that of untreated control cells. In conclusion, suppression of cAMP/PKA/CREB signaling axis improves fibroblast plasticity for direct cardiac reprogramming.
ARTICLE | doi:10.20944/preprints201909.0047.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: Kidney; hypertonicity; osmotic stress; lipocalin-2; lipocalin-2 receptor; lipopolysaccharide; TonEBP; CREB
Online: 4 September 2019 (14:24:49 CEST)
The rodent collecting duct (CD) expresses a 24p3/NGAL/lipocalin-2 (Lcn2) receptor (Slc22a17) apically to possibly mediate high-affinity reabsorption of filtered proteins by endocytosis, yet its functions remain uncertain. Recently, we showed that hyperosmolarity/-tonicity upregulates Slc22a17 in cultured mouse inner medullary CD cells, whereas activation of toll-like receptor 4 (TLR4) via bacterial lipopolysaccharides (LPS) downregulates Slc22a17. This is similar to the upregulation of Aqp2 by hyperosmolarity/-tonicity and arginine vasopressin (AVP) and downregulation by TLR4 signaling that occur via the transcription factors Nfat5 (TonEBP or OREBP), cAMP-responsive element binding protein (CREB), and nuclear factor-kappa B, respectively. The aim of the study was to determine the effects of osmolarity/tonicity via Nfat5, AVP via CREB and TLR4 signaling on the expression of Slc22a17 and its ligand Lcn2 in the mouse (m) cortical collecting duct cell line mCCD(cl.1). Normosmolarity/-tonicity was 300 mosmol/l whereas addition of 50-100 mmol/l NaCl for up to 72 h induced hyperosmolarity/-tonicity (400-500 mosmol/l). RT-PCR, qPCR, immunoblotting and immunofluorescence microscopy detected Slc22a17 and Lcn2 expression. RNAi silenced Nfat5, and the pharmacological agent 666-15 blocked CREB. Activation of TLR4 occurred with LPS. Similar to Aqp2, hyperosmotic/-tonic media and AVP upregulated Slc22a17 via activation of Nfat5 and CREB, respectively, and LPS/TLR4 signaling downregulated Slc22a17. Conversely, though Nfat5 mediated hyperosmolarity/-tonicity induced downregulation of Lcn2 expression, AVP reduced Lcn2 expression and predominantly apical Lcn2 secretion evoked by LPS, but through a posttranslational mode of action that was independent of cAMP signaling. In conclusion, the hyperosmotic/-tonic upregulation of Slc22a17 in mCCD(cl.1) cells via Nfat5 and by AVP via CREB suggests a contribution of Slc22a17 to adaptive osmotolerance, whereas Lcn2 downregulation could counteract increased proliferation and permanent damage of osmotically stressed cells.