Dusp6 is a genetic modifier of growth through enhanced ERK activity

Alcohol Consumption During Adolescence Alters the Cognitive Function in Adult Male Mice by Persistently Increasing Levels of DUSP6

Binge alcohol drinking during adolescence has long-term effects on the adult brain that alter brain structure and behaviors, but the underlying mechanisms remain poorly understood. Extracellular signal-regulated kinase (ERK) is involved in the synaptic plasticity and pathological brain injury by regulating the expression of cyclic adenosine monophosphate response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF). Dual-specificity phosphatase 6 (DUSP6) is a critical effector that dephosphorylates ERK1/2 to control the basal tone, amplitude, and duration of ERK signaling. To explore DUSP6 as a regulator of ERK signaling in the mPFC and its impact on long-term effects of alcohol, a male mouse model of adolescent intermittent alcohol (AIA) exposure was established. Behavioral experiments showed that AIA did not affect anxiety-like behavior or sociability in adulthood, but significantly damaged new object recognition and social recognition memory. Molecular studies further found that AIA reduced the levels of pERK-pCREB-BDNF-PSD95/NR2A involved in synaptic plasticity, while DUSP6 was significantly increased. Intra-mPFC infusion of AAV-DUSP6-shRNA restored the dendritic spine density and postsynaptic density thickness by reversing the level of p-ERK and its downstream molecular expression, and ultimately repaired adult cognitive impairment caused by chronic alcohol exposure during adolescence. These findings indicate that AIA exposure inhibits ERK-CREB-BDNF-PSD95/NR2A by increasing DUSP6 in the mPFC in adulthood that may be associated with long-lasting cognitive deficits.

The super-healing MRL strain promotes muscle growth in muscular dystrophy through a regenerative extracellular matrix

The Murphy Roths Large (MRL) mouse strain has "super-healing" properties that enhance recovery from injury. In mice, the DBA/2J strain intensifies many aspects of muscular dystrophy, so we evaluated the ability of the MRL strain to suppress muscular dystrophy in the Sgcg-null mouse model of limb girdle muscular dystrophy. A comparative analysis of Sgcg-null mice in the DBA/2J versus MRL strains showed greater myofiber regeneration, with reduced structural degradation of muscle in the MRL strain. Transcriptomic profiling of dystrophic muscle indicated strain-dependent expression of extracellular matrix (ECM) and TGF-β signaling genes. To investigate the MRL ECM, cellular components were removed from dystrophic muscle sections to generate decellularized myoscaffolds. Decellularized myoscaffolds from dystrophic mice in the protective MRL strain had significantly less deposition of collagen and matrix-bound TGF-β1 and TGF-β3 throughout the matrix. Dystrophic myoscaffolds from the MRL background, but not the DBA/2J background, were enriched in myokines like IGF-1 and IL-6. C2C12 myoblasts seeded onto decellularized matrices from Sgcg-/- MRL and Sgcg-/- DBA/2J muscles showed the MRL background induced greater myoblast differentiation compared with dystrophic DBA/2J myoscaffolds. Thus, the MRL background imparts its effect through a highly regenerative ECM, which is active even in muscular dystrophy.

Analysis of Fat Graft Survival and Platelet-Rich Plasma Effects: The Transcriptomic Differences

INTRODUCTION

Fat graft survival has been studied numerously but has not gone beyond hypothetical solutions. The molecular changes in survival of standard fat grafts and enhanced survival by platelet-rich plasma (PRP) are compared in this study to reveal the etiology that causes the loss of fat grafts after transplantation.

MATERIALS AND METHODS

A New Zealand rabbit's inguinal fat pads were excised and divided into three groups: Sham, Control (C), and PRP. Each weighing 1 g, C and PRP fat were placed into the bilateral parascapular area of the rabbit. After 30 days, the remaining fat grafts were harvested and weighed (C = 0.7 g, PRP = 0.9 g). All three specimens were put into transcriptome analysis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes Analysis were done to compare the genetic pathways between the specimens.

RESULTS

Transcriptome analysis showed similar differential expressions in Sham vs. PRP and Sham vs. C comparisons, indicating the dominance of the cellular immune response in both C and PRP specimens. C and PRP comparison resulted in inhibited migration and inflammation pathways in PRP.

CONCLUSION

Fat graft survival is more related to immune responses than any other physiological process. PRP enhances survival by attenuating cellular immune reactions.

Identification of common molecular signatures of SARS-CoV-2 infection and its influence on acute kidney injury and chronic kidney disease

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the main cause of COVID-19, causing hundreds of millions of confirmed cases and more than 18.2 million deaths worldwide. Acute kidney injury (AKI) is a common complication of COVID-19 that leads to an increase in mortality, especially in intensive care unit (ICU) settings, and chronic kidney disease (CKD) is a high risk factor for COVID-19 and its related mortality. However, the underlying molecular mechanisms among AKI, CKD, and COVID-19 are unclear. Therefore, transcriptome analysis was performed to examine common pathways and molecular biomarkers for AKI, CKD, and COVID-19 in an attempt to understand the association of SARS-CoV-2 infection with AKI and CKD. Three RNA-seq datasets (GSE147507, GSE1563, and GSE66494) from the GEO database were used to detect differentially expressed genes (DEGs) for COVID-19 with AKI and CKD to search for shared pathways and candidate targets. A total of 17 common DEGs were confirmed, and their biological functions and signaling pathways were characterized by enrichment analysis. MAPK signaling, the structural pathway of interleukin 1 (IL-1), and the Toll-like receptor pathway appear to be involved in the occurrence of these diseases. Hub genes identified from the protein-protein interaction (PPI) network, including DUSP6, BHLHE40, RASGRP1, and TAB2, are potential therapeutic targets in COVID-19 with AKI and CKD. Common genes and pathways may play pathogenic roles in these three diseases mainly through the activation of immune inflammation. Networks of transcription factor (TF)-gene, miRNA-gene, and gene-disease interactions from the datasets were also constructed, and key gene regulators influencing the progression of these three diseases were further identified among the DEGs. Moreover, new drug targets were predicted based on these common DEGs, and molecular docking and molecular dynamics (MD) simulations were performed. Finally, a diagnostic model of COVID-19 was established based on these common DEGs. Taken together, the molecular and signaling pathways identified in this study may be related to the mechanisms by which SARS-CoV-2 infection affects renal function. These findings are significant for the effective treatment of COVID-19 in patients with kidney diseases.

The ties that bind: functional clusters in limb-girdle muscular dystrophy

The limb-girdle muscular dystrophies (LGMDs) are a genetically pleiomorphic class of inherited muscle diseases that are known to share phenotypic features. Selected LGMD genetic subtypes have been studied extensively in affected humans and various animal models. In some cases, these investigations have led to human clinical trials of potential disease-modifying therapies, including gene replacement strategies for individual subtypes using adeno-associated virus (AAV) vectors. The cellular localizations of most proteins associated with LGMD have been determined. However, the functions of these proteins are less uniformly characterized, thus limiting our knowledge of potential common disease mechanisms across subtype boundaries. Correspondingly, broad therapeutic strategies that could each target multiple LGMD subtypes remain less developed. We believe that three major "functional clusters" of subcellular activities relevant to LGMD merit further investigation. The best known of these is the glycosylation modifications associated with the dystroglycan complex. The other two, mechanical signaling and mitochondrial dysfunction, have been studied less systematically but are just as promising with respect to the identification of significant mechanistic subgroups of LGMD. A deeper understanding of these disease pathways could yield a new generation of precision therapies that would each be expected to treat a broader range of LGMD patients than a single subtype, thus expanding the scope of the molecular medicines that may be developed for this complex array of muscular dystrophies.

DUSP6 protects murine podocytes from high glucose‑induced inflammation and apoptosis

Diabetic nephropathy (DN) is one of the most severe complications that can occur in patients with diabetes, and without effective and timely therapeutic intervention, can gradually progress to renal failure. Previous studies have focused on investigating the pathogenesis of DN; however, the role of dual‑specificity phosphatase 6 (DUSP6) in DN is not completely understood. Therefore, the present study aimed to investigate the role of dual‑specificity phosphatase 6 (DUSP6) in DN. DN model mice were established and the expression levels of DUSP6 in the kidney tissues and high glucose (HG)‑induced murine podocytes (MPC5 cells) were determined using immunohistochemistry, reverse transcription‑quantitative PCR and western blotting. In addition, the levels of reactive oxygen species (ROS) and inflammatory cytokines in MPC5 cells were analyzed using commercial assay kits or ELISA kits, respectively, and flow cytometric analysis was performed to analyze the rate of cell apoptosis. The present study indicated that DUSP6 expression levels were significantly decreased in DN model mice compared with control mice, and in HG‑induced MPC5 cells compared with normal glucose‑induced MPC5 cells. DUSP6 overexpression enhanced MPC5 cell viability and increased protein expression levels of cell markers, such as synaptopodin and nephrin, compared with the negative control group. DUSP6 overexpression also reduced the levels of ROS and inflammatory cytokines, including interleukin (IL)‑1β, IL‑6 and tumor necrosis factor‑α secreted by MPC5 cells under HG conditions. Moreover, compared with the HG group, cell apoptosis was inhibited by DUSP6 overexpression under HG conditions, which was further indicated by decreased expression levels of cleaved caspase‑3 and Bax. Thus, these findings indicated that DUSP6 mediated the protection against HG‑induced inflammatory response.

ERK1/2 signaling induces skeletal muscle slow fiber-type switching and reduces muscular dystrophy disease severity

Mitogen-activated protein kinase (MAPK) signaling consists of an array of successively acting kinases. The extracellular signal-regulated kinases 1/2 (ERK1/2) are major components of the greater MAPK cascade that transduce growth factor signaling at the cell membrane. Here we investigated ERK1/2 signaling in skeletal muscle homeostasis and disease. Using mouse genetics, we observed that the muscle-specific expression of a constitutively active MEK1 mutant promotes greater ERK1/2 signaling that mediates fiber-type switching to a slow, oxidative phenotype with type I myosin heavy chain expression. Using a conditional and temporally regulated Cre strategy as well as Mapk1 (ERK2) and Mapk3 (ERK1) genetically targeted mice, MEK1-ERK2 signaling was shown to underlie this fast-to-slow fiber type switching in adult skeletal muscle as well as during development. Physiologic assessment of these activated MEK1-ERK1/2 mice showed enhanced metabolic activity and oxygen consumption with greater muscle fatigue resistance. Moreover, induction of MEK1-ERK1/2 signaling increased dystrophin and utrophin protein expression in a mouse model of limb-girdle muscle dystrophy and protected myofibers from damage. In summary, sustained MEK1-ERK1/2 activity in skeletal muscle produces a fast-to-slow fiber-type switch that protects from muscular dystrophy, suggesting a therapeutic approach to enhance the metabolic effectiveness of muscle and protect from dystrophic disease.