The functions of Sertoli cells in spermatogenesis have attracted much more attention recently. Normal spermatogenesis depends on Sertoli cells, mainly due to their influence on nutrient supply, ...maintenance of cell junctions, and support for germ cells' mitosis and meiosis. Accumulating evidence in the past decade has highlighted the dominant functions of the MAPK, AMPK, and TGF-β/Smad signaling pathways during spermatogenesis. Among these pathways, the MAPK signaling pathway regulates dynamics of tight junctions and adherens junctions, proliferation and meiosis of germ cells, proliferation and lactate production of Sertoli cells; the AMPK and the TGF-β/Smad signaling pathways both affect dynamics of tight junctions and adherens junctions, as well as the proliferation of Sertoli cells. The AMPK signaling pathway also regulates lactate supply. These signaling pathways combine to form a complex regulatory network for spermatogenesis. In testicular tumors or infertile patients, the activities of these signaling pathways in Sertoli cells are abnormal. Clarifying the mechanisms of signaling pathways in Sertoli cells on spermatogenesis provides new insights into the physiological functions of Sertoli cells in male reproduction, and also serves as a pre-requisite to identify potential therapeutic targets in abnormal spermatogenesis including testicular tumor and male infertility.
During eukaryote cell division, molecular motors are crucial regulators of microtubule organization, spindle assembly, chromosome segregation and intracellular transport. The kinesin-14 motors are ...evolutionarily conserved minus-end-directed kinesin motors that occur in diverse organisms from simple yeasts to higher eukaryotes. Members of the kinesin-14 motor family can bind to, crosslink or slide microtubules and, thus, regulate microtubule organization and spindle assembly. In this Commentary, we present the common subthemes that have emerged from studies of the molecular kinetics and mechanics of kinesin-14 motors, particularly with regard to their non-processive movement, their ability to crosslink microtubules and interact with the minus- and plus-ends of microtubules, and with microtubule-organizing center proteins. In particular, counteracting forces between minus-end-directed kinesin-14 and plus-end-directed kinesin-5 motors have recently been implicated in the regulation of microtubule nucleation. We also discuss recent progress in our current understanding of the multiple and fundamental functions that kinesin-14 motors family members have in important aspects of cell division, including the spindle pole, spindle organization and chromosome segregation.
Endometriosis, an estrogen-dependent chronic gynecological disease, is common in reproductive-age women and profoundly affects their life quality. Although various pathogenic theories have been ...proposed, the origin of endometriosis remains unclear. Epithelial to mesenchymal transition (EMT) is a process that epithelial cells lose polarized organization of the cytoskeleton and cell-to-cell contacts, acquiring the high motility of mesenchymal cells. These changes are thought to be prerequisites for the original establishment of endometriotic lesions. However, no study exactly indicates which type of EMT occurs in endometriosis. In this review, we conclude that two different types of EMT may participate in this disease. Besides, two stimulating signals, hypoxia and estrogen, can through different pathways to activate the EMT process in endometriosis. Those pathways involve many cellular factors such as TGF-beta and Wnt, ultimately leading to cell proliferation and migration. As infertility is becoming a serious and intractable issue for women, EMT, during the implantation process, is gaining attention. In this review, we will describe the known functions of EMT in endometriosis, and suggest further studies that may aid in the development of medical therapy.
In metazoa, SOX family transcription factors play many diverse roles. In vertebrate, they are well-known regulators of numerous developmental processes. Wide-ranging studies have demonstrated the ...co-expression of SOX proteins in various developing tissues and that they occur in an overlapping manner and show functional redundancy. In particular, studies focusing on the HMG box of SOX proteins have revealed that the HMG box regulates DNA-binding properties, and mediates both the nucleocytoplasmic shuttling of SOX proteins and their physical interactions with partner proteins. Posttranslational modifications are further implicated in the regulation of the transcriptional activities of SOX proteins. In this review, we discuss the underlying molecular mechanisms involved in the SOX-partner factor interactions and the functional modes of SOX-partner complexes during development. We particularly emphasize the representative roles of the SOX group proteins in major tissues during developmental and physiological processes.
•Arp2/3 complex, Formin1, Eps8, Palladin and Plastin3 regulate actin in testis.•22 actin binding/regulatory proteins which maintain spermatogenesis are reviewed.•PI3K/Akt, AMPK signal pathways ...mediate actin cytoskeleton during spermatogenesis.•mTORC1 and mTORC2 regulate actin-enrich structures via actin binding proteins.
Spermatogenesis is a highly complex physiological process which contains spermatogonia proliferation, spermatocyte meiosis and spermatid morphogenesis. In the past decade, actin binding proteins and signaling pathways which are critical for regulating the actin cytoskeleton in testis had been found. In this review, we summarized 5 actin-binding proteins that have been proven to play important roles in the seminiferous epithelium. Lack of them perturbs spermatids polarity and the transport of spermatids. The loss of Arp2/3 complex, Formin1, Eps8, Palladin and Plastin3 cause sperm release failure suggesting their irreplaceable role in spermatogenesis. Actin regulation relies on multiple signal pathways. The PI3K/Akt signaling pathway positively regulate the mTOR pathway to promote actin reorganization in seminiferous epithelium. Conversely, TSC1/TSC2 complex, the upstream of mTOR, is activated by the LKB1/AMPK pathway to inhibit cell proliferation, differentiation and migration. The increasing researches focus on the function of actin binding proteins (ABPs), however, their collaborative regulation of actin patterns and potential regulatory signaling networks remains unclear. We reviewed ABPs that play important roles in mammalian spermatogenesis and signal pathways involved in the regulation of microfilaments. We suggest that more relevant studies should be performed in the future.
The functional sperm is the key factor for species continuation. The process spermatogenesis, to produce mature sperm is quite complex. It begins with the proliferation and differentiation of ...spermatogonia, which develop from primary spermatocytes to secondary spermatocytes and round spermatids, which eventually develop into fertile mature sperm. Spermiogenesis is the latest stage of spermatogenesis, where the round spermatids undergo a series of dramatic morphological changes and extreme condensation of chromatin to construct mature sperm with species-specific shape. During spermiogenesis, chromatin remodeling is a unique progress. It leads the nucleosome from a histone-based structure to a mostly protamine-based configuration. The main events of chromatin remodeling are the replacement of histone by histone variants, hyperacetylation, transient DNA strand breaks and repair, variants by transition proteins and finally by protamines. In this review, we synthesize and summarize the current knowledge on the progress of chromatin remodeling during spermiogenesis. We straighten out the chronological order of chromatin remodeling and illustrate the possible regulation mechanisms of each step.
•Histone replacement sets basis for subsequent histone modifications.•Hyperacetylation leads to the presence of loosening and opening chromatin.•The transient DNA strand break is an indispensable step for DNA relaxation.
The hypothalamic–pituitary–gonadal axis (HPG) plays vital roles in reproduction and steroid hormone production in both sexes. The focus of this review is upon gene structures, receptor structures and ...the signaling pathways of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The hormones' functions in reproduction as well as consequences resulting from mutations are also summarized. Specific characteristics of hormones such as the pulsatile secretions of GnRH are also covered. The different regulators of the HPG axis are introduced including kisspeptin, activin, inhibin, follistatin, androgens and estrogen. This review includes not only their basic information, but also their unique function in the HPG axis. Here we view the HPG axis as a whole, so relations between ligands and receptors are well described crossing different levels of the HPG axis. Hormone interactions and transformations are also considered. The major information of this article is depicted in three figures summarizing the current discoveries on the HPG axis. This article systematically introduces the basic knowledge of the HPG axis and provides information of the current advances relating to reproductive hormones.
•Hormone gene expression and regulation of the HPG axis are reviewed.•Molecular pathways between reproduction hormones and the receptors are summarized.•Feedback regulation and specific features of reproduction hormones are introduced.•Recent studies together with widely-accepted theories are summarized exhaustively.
Kinesins are essential for the transport and positioning of several biomolecules through moving along the microtubule in eukaryotic cells. Up to now, there are 14 kinesin family proteins known. The ...MAPK pathway which is composed of multiple proteins constituting a complex cascade also plays important roles in cell proliferation, differentiation and apoptosis in eukaryotic cells. MAPK pathway includes three main kinases: MAPK Kinase Kinase, MAPK Kinase and mitogen-activated protein kinase that activate and phosphorylate downstream step by step in which abundant proteins scaffold together in complex ways. To accomplish the transmission of a variety of signals, numbers of kinesins are closely associated with the MAPK cascade such as Kinesin-1, Kinesin-3, Kinesin-5, Kinesin-8, Kinesin-11 and Kinesin-13 families in mammals and two kinds of kinesin-like proteins in plants. Studies have indicated that Kinesin-1 light chain KLC1, Kinesin-1 heavy chain KIF5B and Kinesin-11 family motor KIF26B interact with extracellular signal-regulated kinase ERK closely to regulate neuronal differentiation and mediate the chemosensitivity of osteosarcoma cells to drugs, Kinesin-3 family motor KIF13B and Kinesin-5 family motor Eg5 perform functions in regulating p38 to regulate the myelination of nervous system and facilitate the spindle elongation and tension, Kinesin-8 family motor MS-KIF18A and three isoforms of kinesin-13 can also connect and interact with MAPK pathway to transport estrogen receptor to the nucleus and control cell migration. In plant cells, NPK1-activating kinesin-like protein 1 NACK and AtNACK1 (HIK) kinesin-like protein HINKEL are two members of the plant-specific kinesin-7. They function as Ras at the upstream of MAPK pathway to regulate cytokinesis. This review summarizes the novel roles of kinesins in MAPK cascade and tries to discuss the mechanism of the interaction between them using mammalian and plant cells as models.
Display omitted
•Kinesins involved in MAPK cascade in eukaryotic cells are first summarized.•Kinesins function in transporting various signals in MAPK step by step.•Kinesins and MAPK pathway work together to regulate various cell activities.•Kinesins in MAPK cascade in mammalian and plant cells are compared.
The nuclear localization signal (NLS) in kinesin-14 KIFC1 is associated with nuclear importins and Ran gradient, but detailed mechanism remains unknown. In this study, we found that KIFC1 proteins ...have specific transport characteristics during cell cycle. In the absence of KIFC1, cell cycle kinetics decrease significantly with a prolonged S phase. After KIFC1 overexpression, the duration of S phase becomes shorten. KIFC1 may transport the recombinant/replicate-related proteins into the nucleus, meanwhile avoiding excessive KIFC1 in the cytoplasm, which results in aberrant microtubule bundling. Interestingly, the deletion of kifc1 in human cells results in a higher ratio of aberrant nuclear membrane, and the degradation of lamin B and lamin A/C. We also found that kifc1 deletion leads to defects in metaphase mitotic spindle assembly, and then results in chromosome structural abnormality. The kifc1
cells finally form micronuclei in daughter cells, and results in aneuploidy and chromosome loss in cell cycle. In this study, we demonstrate that kinesin-14 KIFC1 proteins involve in regulating DNA synthesis in S phase, and chromatin maintenance in mitosis, and maintain cell growth in a nuclear transport-independent way.
Engineered nanoparticles (ENPs) have been widely applied in industry, commodities, biology and medicine recently. The potential for many related threats to human health has been highlighted. ENPs ...with their sizes no larger than 100 nm are able to enter the human body and accumulate in organs such as brain, liver, lung, testes, etc, and cause toxic effects. Many references have studied ENP effects on the cells of different organs with related cell apoptosis noted. Understanding such pathways towards ENP induced apoptosis may aid in the design of effective cancer targeting ENP drugs. Such ENPs can either have a direct effect towards cancer cell apoptosis or can be used as drug delivery agents. Characteristics of ENPs, such as sizes, shape, forms, charges and surface modifications are all seen to play a role in determining their toxicity in target cells. Specific modifications of such characteristics can be applied to reduce ENP bioactivity and thus alleviate unwanted cytotoxicity, without affecting the intended function. This provides an opportunity to design ENPs with minimum toxicity to non-targeted cells.
PDF
