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Why regeneration does not occur in mammals remains elusive. In lower vertebrates, epimorphic regeneration of the limb is directed by the wound epidermis, which controls blastema formation to promote regrowth of the appendage. Herein, we report that knockout (KO) or inhibition of Apoptosis Signal-regulated Kinase-1 (ASK1), also known as mitogen-activated protein kinase kinase kinase 5 (MAP3K5), after full thickness ear punch in mice prolongs keratinocyte activation within the wound epidermis and promotes regeneration of auricular cartilage. Histological analysis showed the ASK1 KO ears displayed enhanced protein markers associated with blastema formation, hole closure and regeneration of auricular cartilage. At seven days after punch, the wound epidermis morphology was markedly different in the KO, showing a thickened stratum corneum with rounded cell morphology and a reduction of both the granular cell layer and decreased expression of filament aggregating protein. In addition, cytokeratin 6 was expressed in the stratum spinosum and granulosum. Topical application of inhibitors of ASK1 (NQDI-1), the upstream ASK1 activator, calcium activated mitogen kinase 2 (KN93), or the downstream target, c-Jun N-terminal kinase (SP600125) also resulted in enhanced regeneration; whereas inhibition of the other downstream target, the p38 α/β isoforms, (SB203580) had no effect. The results of this investigation indicate ASK1 inhibition prolongs keratinocyte and blastemal cell activation leading to ear regeneration. [ABSTRACT FROM AUTHOR]

Apoptosis signal-regulated kinase 1 (ASK1) has been shown to affect a wide range of cellular processes including stress-related responses, cytokine and growth factor signaling, cell cycle and cell death. Recently, we reported that lack of ASK1 slowed chondrocyte hypertrophy, terminal differentiation and apoptosis resulting in an increase in trabecular bone formation. Herein, we investigated the role of ASK1 in the pathogenesis of osteoarthritis (OA). Immunohistochemistry performed on articular cartilage samples from patients with OA showed ASK1 expression increased with OA severity. In vitro analysis of chondrocyte hypertrophy, maturation and ASK1 signaling in embryonic fibroblasts from ASK1 knockout (KO) and wild type (WT) mice was examined. Western analysis demonstrated an increase in ASK1 signaling commensurate with chondrogenic maturation during differentiation or in response to stress by the cytokines, tumor necrosis factor alpha or interleukin 1 beta in WT, but not in ASK1 KO embryonic fibroblasts. Surgically induced moderate or severe OAorOA due to natural aging in WT and ASK1 KO mice was assessed by microCT of subchondral bone, immunohistochemistry, histology, and OARSI scoring. Immunohistochemistry, microCT and OARSI scoring all indicated that the lack of ASK1 protected against OA joint degeneration, both in surgically induced OA and in aging mice. We propose that the ASK1 MAP kinase signaling cascade is an important regulator of chondrocyte terminal differentiation and inhibitors of this pathway could be useful for slowing chondrocyte maturation and cell death observed with OA progression. [ABSTRACT FROM AUTHOR]

Cerebral palsy (CP) is a condition resulting from perinatal brain injury and can lead to physical disabilities. Exosomes derived from human amniotic mesenchymal stromal cells (hAMSC-Exos) hold promise as potential therapeutic options. This study aimed to investigate the impact of hAMSC-Exos on neuronal cells and their role in regulating apoptosis both in vitro and in vivo. hAMSC-Exos were isolated via ultracentrifugation and characterized via transmission electron microscopy, particle size analysis, and flow cytometry. In vitro, neuronal damage was induced by lipopolysaccharide (LPS). CP rat models were established via left common carotid artery ligation. Apoptosis levels in cells and CP rats were assessed using flow cytometry, quantitative reverse transcription polymerase chain reaction (RT–qPCR), Western blotting, and TUNEL analysis. The results demonstrated successful isolation of hAMSC-Exos via ultracentrifugation, as the isolated cells were positive for CD9 (79.7%) and CD63 (80.2%). Treatment with hAMSC-Exos significantly mitigated the reduction in cell viability induced by LPS. Flow cytometry revealed that LPS-induced damage promoted apoptosis, but this effect was attenuated by treatment with hAMSC-Exos. Additionally, the expression of caspase-3 and caspase-9 and the Bcl-2/Bax ratio indicated that excessive apoptosis could be attenuated by treatment with hAMSC-Exos. Furthermore, tail vein injection of hAMSC-Exos improved the neurobehavioral function of CP rats. Histological analysis via HE and TUNEL staining showed that apoptosis-related damage was attenuated following hAMSC-Exo treatment. In conclusion, hAMSC-Exos effectively promote neuronal cell survival by regulating apoptosis, indicating their potential as a promising therapeutic option for CP that merits further investigation. [Display omitted] • hAMSC-Exos enhance neurobehavioral outcomes in cerebral palsy model rats. • hAMSC-Exos counteract LPS-induced damage, preserving neuronal viability in vitro. • Caspase-3 expression, Caspase-9 expression, the Bcl-2/Bax ratio suggest that hAMSC-Exos suppress apoptosis. • hAMSC-Exos have potential clinical value in cerebral palsy treatment. [ABSTRACT FROM AUTHOR]

Psoriasis is a multifactorial disease and the mechanisms involved in its pathogenesis remain to be elucidated. FOS-like antigen 1 (Fra-1) is a proto-oncogene. It is a negative inhibitor of activator protein-1 activity and possesses transforming activity. The effect of and possible mechanisms underlying Fra-1 in psoriasis remain to be elucidated. In the present study, western blot analysis and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) techniques were used to identify differentially expressed Fra-1 in psoriatic and in normal control tissues. Compared with the control samples, the expression of normalized Fra-1 genes in psoriasis was 12.6 times higher. Western blot analysis was used to assess the protein levels of Fra-1. The results demonstrated that the protein expression of Fra-1 was high in tissues affected by psoriasis. This also corresponded with the results of RT-qPCR. Fra-1-stable expressing HaCaT/Fra-1 or control HaCaT/vector cell lines were then generated to elucidate the function of Fra-1 in the growth of HaCaT cells. The results demonstrated that Fra-1 promoted the growth of HaCaT cells in vitro by arresting the cell cycle and inhibiting cell apoptosis. These results suggested that Fra-1 may be important in psoriasis. [ABSTRACT FROM AUTHOR]