Palmitoyl Protein Thioesterase 1 Is Essential for Myogenic Autophagy of C2C12 Skeletal Myoblast

Melatonin protects aged oocytes from depalmitoylation-mediated quality reduction by promoting PPT1 degradation and antioxidation

Oocyte aging is closely related to a decline in female fertility, accompanied by increased reactive oxygen species levels and changes in protein posttranslational modifications. However, the role of protein palmitoylation in oocyte aging has not been investigated. In the present study, a new association between redox and palmitoylation in aging oocytes was found. We found that the protein level of palmitoyl-protein thioesterase 1 (PPT1), a depalmitoylation enzyme, was increased in maternally aged mice oocytes and follicular fluid of aged (age >35 years) patients with decreased ovarian reserve (DOR). Elevated PPT1 led to decreased S-palmitoylation levels in oocytes, which impaired oocyte maturation and spindle formation. Tubulin was identified as a critical palmitoylated protein regulated by PPT1, whose palmitoylation was also decreased by advanced age, accompanied by abnormalities in membrane localization and microtubule polymerization. Melatonin was found to down-regulate excessive PPT1 and rescue PPT1-induced damage in mouse oocytes, not only by regulating oxidative stress, but also by binding with PPT1 to regulate its lysosomal degradation. In summary, our data demonstrate that PPT1 participates in oocyte aging by regulating tubulin palmitoylation, providing evidence that oxidative stress regulates protein palmitoylation and revealing a novel mechanism of oocyte aging.

Transcriptional regulation of autophagy in skeletal muscle stem cells

Muscle stem cells (MuSCs) are essential for the regenerative capabilities of skeletal muscles. MuSCs are maintained in a quiescent state, but, when activated, can undergo proliferation and differentiation into myocytes, which fuse and mature to generate muscle fibers. The maintenance of MuSC quiescence and MuSC activation are processes that are tightly regulated by autophagy, a conserved degradation system that removes unessential or dysfunctional cellular components via lysosomes. Both the upregulation and downregulation of autophagy have been linked to impaired muscle regeneration, causing myopathies such as cancer cachexia, sarcopenia and Duchenne muscular dystrophy. In this Review, we highlight the importance of autophagy in regulating MuSC activity during muscle regeneration. Additionally, we summarize recent studies that link the transcriptional dysregulation of autophagy to muscle atrophy, emphasizing the dominant roles that transcription factors play in myogenic programs. Deciphering and understanding the roles of these transcription factors in the regulation of autophagy during myogenesis could advance the development of regenerative medicine.

Tumor purity-associated genes influence hepatocellular carcinoma prognosis and tumor microenvironment

Introduction

Tumor purity takes on critical significance to the progression of solid tumors. The aim of this study was at exploring potential prognostic genes correlated with tumor purity in hepatocellular carcinoma (HCC) by bioinformatics analysis.

Methods

The ESTIMATE algorithm was applied for determining the tumor purity of HCC samples from The Cancer Genome Atlas (TCGA). The tumor purity-associated genes with differential expression (DEGs) were identified based on overlap analysis, weighted gene co-expression network analysis (WGCNA), and differential expression analysis. The prognostic genes were identified in terms of the prognostic model construction based on the Kaplan-Meier (K-M) survival analysis and Least Absolute Shrinkage and Selection Operator (LASSO) regression analyses. The expression of the above-described genes was further validated by the GSE105130 dataset from the Gene Expression Omnibus (GEO) database. We also characterized the clinical and immunophenotypes of prognostic genes. Gene set enrichment analysis (GSEA) was carried out for exploring the biological signaling pathway.

Results

A total of 26 tumor purity-associated DEGs were identified, which were involved in biological processes such as immune/inflammatory responses and fatty acid elongation. Ultimately, we identified ADCK3, HK3, and PPT1 as the prognostic genes for HCC. Moreover, HCC patients exhibiting higher ADCK3 expression and lower HK3 and PPT1 expressions had a better prognosis. Furthermore, high HK3 and PPT1 expressions and low ADCK3 expression resulted in high tumor purity, high immune score, high stromal score, and high ESTIMATE score. GSEA showed that the abovementioned prognostic genes showed a significant correlation with immune-inflammatory response, tumor growth, and fatty acid production/degradation.

Discussion

In conclusion, this study identified novel predictive biomarkers (ADCK3, HK3, and PPT1) and studied the underlying molecular mechanisms of HCC pathology initially.

Autophagy in the Neuronal Ceroid Lipofuscinoses (Batten Disease)

The neuronal ceroid lipofuscinoses (NCLs), also referred to as Batten disease, are a family of neurodegenerative diseases that affect all age groups and ethnicities around the globe. At least a dozen NCL subtypes have been identified that are each linked to a mutation in a distinct ceroid lipofuscinosis neuronal (CLN) gene. Mutations in CLN genes cause the accumulation of autofluorescent lipoprotein aggregates, called ceroid lipofuscin, in neurons and other cell types outside the central nervous system. The mechanisms regulating the accumulation of this material are not entirely known. The CLN genes encode cytosolic, lysosomal, and integral membrane proteins that are associated with a variety of cellular processes, and accumulated evidence suggests they participate in shared or convergent biological pathways. Research across a variety of non-mammalian and mammalian model systems clearly supports an effect of CLN gene mutations on autophagy, suggesting that autophagy plays an essential role in the development and progression of the NCLs. In this review, we summarize research linking the autophagy pathway to the NCLs to guide future work that further elucidates the contribution of altered autophagy to NCL pathology.

Echinochrome A Treatment Alleviates Atopic Dermatitis-like Skin Lesions in NC/Nga Mice via IL-4 and IL-13 Suppression

Atopic dermatitis (AD) is a chronic inflammatory skin disease in which skin barrier dysfunction leads to dryness, pruritus, and erythematous lesions. AD is triggered by immune imbalance and oxidative stress. Echinochrome A (Ech A), a natural pigment isolated from sea urchins, exerts antioxidant and beneficial effects in various inflammatory disease models. In the present study, we tested whether Ech A treatment alleviated AD-like skin lesions. We examined the anti-inflammatory effect of Ech A on 2,4-dinitrochlorobenzene (DNCB)-induced AD-like lesions in an NC/Nga mouse model. AD-like skin symptoms were induced by treatment with 1% DNCB for 1 week and 0.4% DNCB for 5 weeks in NC/Nga mice. The results showed that Ech A alleviated AD clinical symptoms, such as edema, erythema, and dryness. Treatment with Ech A induced the recovery of epidermis skin lesions as observed histologically. Tewameter^® and Corneometer^® measurements indicated that Ech A treatment reduced transepidermal water loss and improved stratum corneum hydration, respectively. Ech A treatment also inhibited inflammatory-response-induced mast cell infiltration in AD-like skin lesions and suppressed the expression of proinflammatory cytokines, such as interferon-γ, interleukin-4, and interleukin-13. Collectively, these results suggest that Ech A may be beneficial for treating AD owing to its anti-inflammatory effects.