Upregulation of nuclear factor-kappaB expression by SLURP-1 is mediated by alpha7-nicotinic acetylcholine receptor and involves both ionic events and activation of protein kinases

Novel cholinergic peptides SLURP-1 and -2 regulate epithelialization of cutaneous and oral wounds

It is well established that auto/paracrine acetylcholine (ACh) is essential for wound epithelialization, and that the mechanisms include regulation of keratinocyte motility and adhesion via nicotinic ACh receptors (nAChRs). Keratinocyte nAChRs can be also activated by non-canonical ligands, such as secreted mammalian Ly-6/urokinase-type plasminogen activator receptor-related protein (SLURP)-1 and -2. In this study, we determined effects of recombinant (r)SLURP-1 and-2 on migration of human epidermal and oral keratinocytes under agarose and epithelialization of cutaneous and oral mucosal excisional wounds in mice, and also identified nAChRs mediating SLURP signals. Both in vitro and in vivo, rSLURP-1 decreased and SLURP-2 increased epithelialization rate. The mixture of both peptides accelerated epithelialization even further, indicating that their simultaneous signaling renders an additive physiologic response. The specificity of rSLURP actions was illustrated by similar effects on cutaneous and oral wounds, which feature distinct responses to injury, and also by abrogation of rSLURP effects with neutralizing antibodies. rSLURP-1 acted predominantly via the α7 nAChR-coupled up-regulation of the sedentary integrins α2 and α3 , whereas SLURP-2--through α3, and α9 nAChRs up-regulating migratory integrins α5 and αV . The biologic effects of rSLURPs required the presence of endogenous ACh, indicating that auto/paracrine SLURPs provide for a fine tuning of the physiologic regulation of crawling locomotion via the keratinocyte ACh axis. Since nAChRs have been shown to regulate SLURP production, cholinergic regulation of keratinocyte migration appears to be mediated by a reciprocally arranged network. The cholinergic peptides, therefore, may become prototype drugs for the treatment of wounds that fail to heal.

Nuclear JAK2: form and function in cancer

The conventional view of Janus kinase 2 (JAK2) is a nonreceptor tyrosine kinase which transmits information to the nucleus via the signal transducer and activator of transcriptions (STATs) without leaving the cytoplasm. However, accumulating data suggest that JAK2 may signal by exporting from cytoplasm to nucleus, where it guides the transcriptional machinery independent of STATs protein. Recent studies demonstrated that JAK2 is a crucial component of signaling pathways operating in the nucleus. Especially the latest landmark discovery confirmed that JAK2 goes into the nucleus and directly interacts with nucleoproteins, such as histone H3 at tyrosine 41 (H3Y41), nuclear factor 1-C2 (NF1-C2) and SWI/SNF-related helicases/ATPases (RUSH)-1α, indicating that JAK2 has a fresh nuclear function. Nuclear JAK2 is linked to a variety of cellular functions, such as cell cycle progression, apoptosis and genetic instability. The balance between these functions is an essential factor in determining whether a cell remains benign or becomes malignant. The aim of this review is intended to summarize the state of our knowledge on nuclear localization of JAK2 and nuclear JAK2 pathways, and to highlight the emerging roles for nuclear JAK2 in carcinogenesis.

α4β2 nicotinic receptors partially mediate anti-inflammatory effects through Janus kinase 2-signal transducer and activator of transcription 3 but not calcium or cAMP signaling

Despite evidence that smoking confers protection against neurological disorders, how and whether specific nicotinic receptor subtypes are involved is unknown. We reported previously that nicotine suppresses constitutive nuclear factor κB (NF-κB) activity and thereby proinflammatory cytokine (PIC) production in SHEP1 cells stably transfected with α4β2 nicotinic receptors. Here, we report the anti-inflammatory effects of nicotine pretreatment in lipopolysaccharide (LPS)-stimulated SHEP1 cells. Nicotine (100-300 nM, concentrations found in smoker's blood) blocked LPS-induced NF-κB translocation and production of PICs interleukin (IL)-1β and IL-6 but only partially blocked inhibitor of nuclear factor-κBα (IκBα) phosphorylation. These effects were exclusively in cells transfected with α4β2 receptors but not in wild types. The cell-permeable calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, the adenylate cyclase stimulant forskolin, and a specific protein kinase A (PKA) inhibitor PKI 14-22-amide failed to block the effect of nicotine on LPS-induced NF-κB translocation and IκBα phosphorylation. However, the effects of nicotine on NF-κB activity were significantly blocked by the highly specific janus kinase 2 (JAK2) inhibitor α-cyano-(3,4-dihydroxy)-N-benzylcinnamide (AG-490) and the signal transducer and activator of transcription 3 (STAT3) inhibitor 2-hydroxy-4-[[[[(4-methylphenyl)sulfonyl]oxy]acetyl]amino]-benzoic acid (NSC74859). These findings reveal a calcium- and cAMP-PKA-independent signaling cascade and suggest a role for JAK2-STAT3 transduction in α4β2-mediated attenuation of LPS-induced inflammation. Anti-inflammatory effects of nicotine may therefore be mediated through α4β2 receptors, the predominant high-affinity binding sites for nicotine in the central nervous system, in addition to the better-established α7 receptors.