Physiological Ovarian Aging Is Associated with Altered Expression of Post-Translational Modifications in Mice

Protein lysine crotonylation in cellular processions and disease associations

Protein lysine crotonylation (Kcr) is one conserved form of posttranslational modifications of proteins, which plays an important role in a series of cellular physiological and pathological processes. Lysine ε-amino groups are the primary sites of such modification, resulting in four-carbon planar lysine crotonylation that is structurally and functionally distinct from the acetylation of these residues. High levels of Kcr modifications have been identified on both histone and non-histone proteins. The present review offers an update on the research progression regarding protein Kcr modifications in biomedical contexts and provides a discussion of the mechanisms whereby Kcr modification governs a range of biological processes. In addition, given the importance of protein Kcr modification in disease onset and progression, the potential viability of Kcr regulators as therapeutic targets is elucidated.

Qualitative lysine crotonylation and 2-hydroxyisobutyrylation analysis in the ovarian tissue proteome of piglets

Ovarian function influences diverse aspects of fertility and reproductive lifespan by regulating oocyte supply and hormone secretion. Lysine crotonylation (Kcr) and lysine 2-hydroxyisobutyryllysine (Khib) are newly identified post-translational modifications and function as regulators of transactivation in mammals. In this study, we investigated protein post-translational Kcr and 2-hydroxyisobutyrylation in the ovarian tissues of piglets. A total of 653 overlapping proteins among differentially modified proteins were identified for both crotonylation and 2-hydroxyisobutyrylation. Gene Ontology enrichment analysis indicated that 653 DMPs were significantly enriched in nucleosome organization, chromatin assembly, DNA packaging, peptide biosynthetic process and peptide metabolic process. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed enrichment in proteasome, ribosome, fatty acid elongation, pyruvate metabolism and pentose phosphate pathway. Fifteen DMPs were identified in the proteasome pathway, of which PSMC6 and PSMB7 were the core proteins. In addition, the significant changes in Kcr and Khib in the complex subunits of the proteasome may be involved in cell cycle processes during oocyte development. Forty-four DMPs with both Kcr and Khib modifications were related to the ribosome pathway. The regulated ribosome pathway may indicate that Kcr and Khib comodified proteins participate in protein synthesis during oocyte development. Western blot and immunofluorescence staining results supported the reliability of the sequencing results. Our results may provide a valuable resource to help illuminate the roles of Kcr and Khib in ovarian development and may serve as new tools to better control diseases.

Immunity and reproduction protective effects of Chitosan Oligosaccharides in Cyclophosphamide/Busulfan-induced premature ovarian failure model mice

Introduction

Premature ovarian failure (POF) is a major cause of infertility among women of reproductive age. Unfortunately, there is no effective treatment available currently. Researchers have shown that immune disorders play a significant role in the development of POF. Moreover, growing evidence suggest that Chitosan Oligosaccharides (COS), which act as critical immunomodulators, may have a key role in preventing and treating a range of immune related reproductive diseases.

Methods

KM mice (6-8 weeks) received a single intraperitoneal injection of cyclophosphamide (CY, 120mg/kg) and busulfan (BUS, 30mg/kg) to establish POF model. After completing the COS pre-treatment or post-treatment procedures, peritoneal resident macrophages (PRMs) were collected for neutral erythrophagocytosis assay to detect phagocytic activity. The thymus, spleen and ovary tissues were collected and weighed to calculate the organ indexes. Hematoxylin-eosin (HE) staining was performed to observe the histopathologic structure of those organs. The serum levels of estrogen (E2) and progesterone (P) were measured via the enzyme-linked immunosorbent assay (ELISA). The expression levels of immune factors including interleukin 2 (IL-2), interleukin 4 (IL-4), and tumor necrosis factor α (TNF-α), as well as germ cell markers Mouse Vasa Homologue (MVH) and Fragilis in ovarian tissue, were analyzed by Western blotting and qRT-PCR. In addition, ovarian cell senescence via p53/p21/p16 signaling was also detected.

Results

The phagocytic function of PRMs and the structural integrity of thymus and spleen were preserved by COS treatment. The levels of certain immune factors in the ovaries of CY/BUS- induced POF mice were found to be altered, manifested as IL-2 and TNF-α experiencing a significant decline, and IL-4 presenting a notable increase. Both pre-treatment and post-treatment with COS were shown to be protective effects against the damage to ovarian structure caused by CY/BUS. Senescence-associated β-galactosidase (SA-β-Gal) staining results showed that COS prevents CY/BUS-induced ovarian cell senescence. Additionally, COS regulated estrogen and progesterone levels, enhanced follicular development, and blocked ovarian cellular p53/p21/p16 signaling which participating in cell senescence.

Conclusion

COS is a potent preventative and therapeutic medicine for premature ovarian failure by enhancing both the ovarian local and systemic immune response as well as inhibiting germ cell senescence.

The emerging role of lysine succinylation in ovarian aging

BACKGROUND

Ovarian aging is a process of decline in its reserve leading to ovary dysfunction and even reduced health quality in offspring. However, aging-related molecular pathways in the ovary remain obscure. Lysine succinylation (Ksuc), a newly post-translational modification (PTM), has been found to be broadly conserved in both eukaryotic and prokaryotic cells, and associated with multiple pathophysiological processes. There are no relevant reports revealing a link between the molecular mechanisms of ovarian aging and Ksuc.

METHODS

The level of Ksuc in ovaries of aged and premature ovarian insufficiency (POI) mice were detected by immunoblotting and immunohistochemical. To further explore the role of Ksuc in ovarian aging, using in vitro mouse ovary tissue culture and an in vivo mouse model with changed Ksuc level.

RESULTS

Increased Ksuc in ovaries of aged and POI mice and distribution of Ksuc in various types of mice ovarian cells and the high level of Ksuc in granulosa cells (GCs) were revealed. Histological assessments and hormone levels analyses showed that the high Ksuc level down-regulated the ovarian index and the anti-Müllerian hormone (AMH) and estrogen levels, and increased follicular atresia. Moreover, in the high Ksuc groups, the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) intensities and the expression of Cleaved-caspase-3 increased and the expression of B-cell lymphoma-2 (Bcl-2) decreased together with positively-expressed P21, an aging-related marker. These results suggest that ovarian aging is likely associated with alteration in Ksuc.

CONCLUSION

The present study has identified Ksuc in mouse ovary and found that high Ksuc level most likely contributes to ovarian aging which is expected further investigation to provide new information for delaying physiological ovarian aging and treating pathological ovarian aging.

The SUV4-20H Histone Methyltransferases in Health and Disease

The post-translational modification of histone tails is a dynamic process that provides chromatin with high plasticity. Histone modifications occur through the recruitment of nonhistone proteins to chromatin and have the potential to influence fundamental biological processes. Many recent studies have been directed at understanding the role of methylated lysine 20 of histone H4 (H4K20) in physiological and pathological processes. In this review, we will focus on the function and regulation of the histone methyltransferases SUV4-20H1 and SUV4-20H2, which catalyze the di- and tri-methylation of H4K20 at H4K20me2 and H4K20me3, respectively. We will highlight recent studies that have elucidated the functions of these enzymes in various biological processes, including DNA repair, cell cycle regulation, and DNA replication. We will also provide an overview of the pathological conditions associated with H4K20me2/3 misregulation as a result of mutations or the aberrant expression of SUV4-20H1 or SUV4-20H2. Finally, we will critically analyze the data supporting these functions and outline questions for future research.