One of the most remarkable chromatin remodelling processes occurs during spermiogenesis, the post-meiotic phase of sperm development during which histones are replaced with sperm-specific protamines to repackage the genome into the highly compact chromatin structure of mature sperm. Here we identify Chromodomain helicase DNA binding protein 5 (Chd5) as a master regulator of the histone-to-protamine chromatin remodelling process. Chd5 deficiency leads to defective sperm chromatin compaction and male infertility in mice, mirroring the observation of low CHD5 expression in testes of infertile men. Chd5 orchestrates a cascade of molecular events required for histone removal and replacement, including histone 4 (H4) hyperacetylation, histone variant expression, nucleosome eviction and DNA damage repair. Chd5 deficiency also perturbs expression of transition proteins (Tnp1/Tnp2) and protamines (Prm1/2). These findings define Chd5 as a multi-faceted mediator of histone-to-protamine replacement and depict the cascade of molecular events underlying this process of extensive chromatin remodelling.

/pdf/chd5-orchestrates-chromatin-remodelling-during-sperm-53w2k9wk2p.pdf

Chd5 orchestrates chromatin remodelling during sperm development.

Epigenetic modifications, and methylation of histones in particular, dynamically change during spermatogenesis. Among various methylations of histone H3, methylation of histone H3 lysine 9 (H3K9) and its regulation are essential for spermatogenesis. Trimethytransferases as well as dimethyltransferase are required for meiotic progression. In addition, didemethylase of H3K9 is also critical for spermatogenesis through transcriptional regulation of spermatid-specific genes. However, the requirement for demethylation of trimethylated H3K9 (H3K9me3) during spermatogenesis remains to be elucidated. Here, we report the targeted disruption of KDM4D, a testis-enriched tridemethylase of H3K9. Kdm4d-null mice are viable and fertile and do not show any obvious phenotype. However, H3K9me3 accumulates significantly in Kdm4d-null round spermatids, and the distribution of methylated H3K9 in germ cells is dramatically changed. Nevertheless, the progression of spermatogenesis and the number of spermatozoa are normal, likely secondary to the earlier nuclear localization of another H3K9 tridemethylase, KDM4B, in Kdm4d-null elongating spermatids. These results suggest that demethylation of H3K9me3 in round spermatids is dispensable for spermatogenesis but that possible defects in Kdm4d-null elongating spermatids could be rescued by functional redundancy of the KDM4B demethylase.

/pdf/the-testis-enriched-histone-demethylase-kdm4d-regulates-1xfr251b6o.pdf

The Testis-Enriched Histone Demethylase, KDM4D, Regulates Methylation of Histone H3 Lysine 9 During Spermatogenesis in the Mouse but Is Dispensable for Fertility

Despite the identification of H2A.Bbd as a new vertebrate-specific replacement histone variant several years ago, and despite the many in vitro structural characterizations using reconstituted chromatin complexes consisting of this variant, the existence of H2A.Bbd in the cell and its location has remained elusive. Here, we report that the native form of this variant is present in highly advanced spermiogenic fractions of mammalian testis at the time when histones are highly acetylated and being replaced by protamines. It is also present in the nucleosomal chromatin fraction of mature human sperm. The ectopically expressed non-tagged version of the protein is associated with micrococcal nuclease-refractory insoluble fractions of chromatin and in mouse (20T1/2) cell line, H2A.Bbd is enriched at the periphery of chromocenters. The exceedingly rapid evolution of this unique X-chromosome-linked histone variant is shared with other reproductive proteins including those associated with chromatin in the mature sperm (protamines) of many vertebrates. This common rate of evolution provides further support for the functional and structural involvement of this protein in male gametogenesis in mammals.

/pdf/h2a-bbd-an-x-chromosome-encoded-histone-involved-in-3asek2mtrd.pdf

H2A.Bbd: an X-chromosome-encoded histone involved in mammalian spermiogenesis

Fertilization is the process that leads to the formation of a diploid zygote from two haploid gametes. This is achieved through a complex series of cell-to-cell interactions between a sperm and an egg. The final event of fertilization is the fusion of the gametes’ membranes, which allows the delivery of the sperm genetic material into the egg cytoplasm. In vivo studies in the laboratory mouse have led to the discovery of membrane proteins that are essential for the fusion process in both the sperm and egg. Specifically, the sperm protein Izumo1 was shown to be necessary for normal fertility. Izumo1-deficient spermatozoa fail to fuse with the egg plasma membrane. Izumo1 is a member of the Immunoglobulin Superfamily of proteins, which are known to be involved in cell adhesion. Here, we describe BART97b, a new mouse line with a recessive mutation that displays a fertilization block associated with a failure of sperm fusion. BART97b mutants carry a deletion that inactivates Spaca6, a previously uncharacterized gene expressed in testis. Similar to Izumo1, Spaca6 encodes an immunoglobulin-like protein. We propose that the Spaca6 gene product may, together with Izumo1, mediate sperm fusion by binding an as yet unidentified egg membrane receptor.

A transgenic insertion on mouse chromosome 17 inactivates a novel immunoglobulin superfamily gene potentially involved in sperm–egg fusion

In the testis, cell adhesion and junctional molecules permit specific interactions and intracellular communication between germ and Sertoli cells and apposed Sertoli cells. Among the many adhesion family of proteins, NCAM, nectin and nectin-like, catenins, and cadherens will be discussed, along with gap junctions between germ and Sertoli cells and the many members of the connexin family. The blood-testis barrier separates the haploid spermatids from blood borne elements. In the barrier, the intercellular junctions consist of many proteins such as occludin, tricellulin, and claudins. Changes in the expression of cell adhesion molecules are also an essential part of the mechanism that allows germ cells to move from the basal compartment of the seminiferous tubule to the adluminal compartment thus crossing the blood-testis barrier and well-defined proteins have been shown to assist in this process. Several structural components show interactions between germ cells to Sertoli cells such as the ectoplasmic specialization which are more closely related to Sertoli cells and tubulobulbar complexes that are processes of elongating spermatids embedded into Sertoli cells. Germ cells also modify several Sertoli functions and this also appears to be the case for residual bodies. Cholesterol plays a significant role during spermatogenesis and is essential for germ cell development. Lastly, we list genes/proteins that are expressed not only in any one specific generation of germ cells but across more than one generation.

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 5: intercellular junctions and contacts between germs cells and Sertoli cells and their regulatory interactions, testicular cholesterol, and genes/proteins associated with more than one germ cell generation.

Utp14b: a unique retrogene within a gene that has acquired multiple promoters and a specific function in spermatogenesis.

Myosin superfamily, a large and diverse family of molecular motors important for cell motility and migration, has been illustrated to play contradictory roles during the development of several kinds of tumors. However, the function and prognostic values of MYOs in head and neck squamous cell carcinoma (HNSCC) still remain largely unknown. In the current manuscript, the expression levels and clinical data of MYOs in HNSCC were investigated by online databases, including Oncomine, GEPIA, GEO, TCGA, HPA, UALCAN, Kaplan-Meier plotter, and CancerSEA; we found that the expression levels of MYO1B, MYO5A, and MYO10 were significantly elevated in HNSCC tissues, which were also correlated with the unfavorable overall survival (OS) of the patients. Furthermore, MYO1B/MYO5A/MYO10 interacting genes were identified, and the protein-protein interaction (PPI) networks were constructed by STRING and GeneMANIA. The enrichment analysis revealed that MYO1B/MYO5A/MYO10 associated genes mainly participated in cell metastasis and EMT processes, which were also confirmed by cell functional experiments. At last, the ssGSEA method was conducted to investigate the extent of immune cell infiltration, and we found that both the expression of MYO1B/MYO5A/MYO10 were closely correlated with the infiltration of immune cells in HNSCC. These findings implied that MYO1B, MYO5A, and MYO10 as novel prognostic factors for HNSCC and provided new strategy for HNSCC treatment.

/pdf/comprehensive-landscape-of-prognostic-significance-and-k56qwig2.pdf

Comprehensive Landscape of Prognostic Significance and Immune Characteristics of Myosins in Squamous Cell Carcinoma of the Head and Neck

Hypopharyngeal squamous cell carcinoma (HSCC) is highly malignant and extremely aggressive, making it one of the worst prognoses among all kinds of head and neck squamous cell carcinoma (HNSCC); therefore, gaining insight into molecular mechanisms of HSCC is of profound significance. In the current manuscript, we revealed the elevated expression of long noncoding RNA (lncRNA) LEF1-AS1 in HNSCC which was associated with the poor prognosis by bioinformatic analysis. Moreover, we noticed that LEF1-AS1 dramatically accelerated the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) process in HSCC cell line FaDu. Most importantly, we illustrated that LEF1-AS1 played as a competitive endogenous RNA (ceRNA) via sponging miR-221-5p and thereby positively regulated gap junction protein alpha 1 (GJA1) expression, thus aggravated tumor progression and EMT. In conclusion, for the first time, we demonstrated lncRNA LEF1-AS1 as a novel biomarker for HNSCC and suggested LEF1-AS1/miR-221-5p/GJA1 axis as promising diagnostic and therapeutic target for HSCC treatment.

/pdf/lncrna-lef1-as1-acts-as-a-novel-biomarker-and-promotes-31defgm2.pdf

lncRNA LEF1-AS1 Acts as a Novel Biomarker and Promotes Hypopharyngeal Squamous Cell Carcinoma Progression and Metastasis by Targeting the miR-221-5p/GJA1 Axis

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Utp14b: a unique retrogene within a gene that has acquired multiple promoters and a specific function in spermatogenesis.

Comprehensive Landscape of Prognostic Significance and Immune Characteristics of Myosins in Squamous Cell Carcinoma of the Head and Neck

lncRNA LEF1-AS1 Acts as a Novel Biomarker and Promotes Hypopharyngeal Squamous Cell Carcinoma Progression and Metastasis by Targeting the miR-221-5p/GJA1 Axis