scholarly journals Altered germline cyst formation and oogenesis in Tex14 mutant mice

Biology Open ◽  
2021 ◽  
Vol 10 (6) ◽  
Author(s):  
Kanako Ikami ◽  
Nafisa Nuzhat ◽  
Haley Abbott ◽  
Ronald Pandoy ◽  
Lauren Haky ◽  
...  
Keyword(s):  
Germ Cells ◽  
Cyst Formation ◽  
Intercellular Bridge ◽  
Wild Type ◽  
Intercellular Bridges ◽  
Mutant Female ◽  
Homozygous Mutant ◽  
Germline Cyst ◽  
Oocyte Differentiation

ABSTRACT During oocyte differentiation in mouse fetal ovaries, sister germ cells are connected by intercellular bridges, forming germline cysts. Within the cyst, primary oocytes form via gaining cytoplasm and organelles from sister germ cells through germ cell connectivity. To uncover the role of intercellular bridges in oocyte differentiation, we analyzed mutant female mice lacking testis-expressed 14 (TEX14), a protein involved in intercellular bridge formation and stabilization. In Tex14 homozygous mutant fetal ovaries, germ cells divide to form a reduced number of cysts in which germ cells remained connected via syncytia or fragmented cell membranes, rather than normal intercellular bridges. Compared with wild-type cysts, homozygous mutant cysts fragmented at a higher frequency and produced a greatly reduced number of primary oocytes with precocious cytoplasmic enrichment and enlarged volume. By contrast, Tex14 heterozygous mutant germline cysts were less fragmented and generate primary oocytes at a reduced size. Moreover, enlarged primary oocytes in homozygous mutants were used more efficiently to sustain folliculogenesis than undersized heterozygous mutant primary oocytes. Our observations directly link the nature of fetal germline cysts to oocyte differentiation and development.

scholarly journals vasa is required for GURKEN accumulation in the oocyte, and is involved in oocyte differentiation and germline cyst development

Development ◽  
1998 ◽  
Vol 125 (9) ◽  
pp. 1569-1578 ◽  
Author(s):  
S. Styhler ◽  
A. Nakamura ◽  
A. Swan ◽  
B. Suter ◽  
P. Lasko
Keyword(s):  
Embryonic Patterning ◽  
Wild Type ◽  
Coding Region ◽  
Cell Specification ◽  
Germline Cyst ◽  
And Function ◽  
Oocyte Differentiation ◽  
Pole Plasm ◽  
Anterior Posterior

The Drosophila gene vasa is required for pole plasm assembly and function, and also for completion of oogenesis. To investigate the role of vasa in oocyte development, we generated a new null mutation of vasa, which deletes the entire coding region. Analysis of vasa-null ovaries revealed that the gene is involved in the growth of germline cysts. In vasa-null ovaries, germaria are atrophied, and contain far fewer developing cysts than do wild-type germaria; a phenotype similar to, but less severe than, that of a null nanos allele. The null mutant also revealed roles for vasa in oocyte differentiation, anterior-posterior egg chamber patterning, and dorsal-ventral follicle patterning, in addition to its better-characterized functions in posterior embryonic patterning and pole cell specification. The anterior-posterior and dorsal-ventral patterning phenotypes resemble those observed in gurken mutants. vasa-null oocytes fail to efficiently accumulate many localized RNAs, such as Bicaudal-D, orb, oskar, and nanos, but still accumulate gurken RNA. However, GRK accumulation in the oocyte is severely reduced in the absence of vasa function, suggesting a function for VASA in activating gurken translation in wild-type ovaries.

Female mouse germ cells form synchronously dividing cysts

Development ◽  
1998 ◽  
Vol 125 (17) ◽  
pp. 3323-3328 ◽  
Author(s):  
M.E. Pepling ◽  
A.C. Spradling
Keyword(s):  
Confocal Microscopy ◽  
Germ Cells ◽  
Female Mouse ◽  
Progenitor Cell ◽  
Molecular Level ◽  
Cyst Formation ◽  
Intercellular Bridges ◽  
Cell Clusters ◽  
Key Characteristics ◽  
Germline Cyst

Oocytes from many invertebrates initiate development within distinctive cysts of interconnected cells, which are formed through synchronous divisions of a progenitor cell. Recently, processes underlying cyst formation have been extensively characterized at the molecular level in Drosophila. Defects in this process cause sterility in female flies. Early female mouse germ cells are organized as cell clusters as well, but it is uncertain whether these groups are similar to the cysts of invertebrates. We find that mouse germ cells are connected by intercellular bridges in the ovaries of 11.5 to 17.5 days postcoitum embryos; microtubules and organelles have been observed within these bridges. Confocal microscopy shows that cells within mouse clusters divide synchronously and frequently correspond in number to powers of two. Thus, female mouse germ cell clusters exhibit key characteristics of invertebrate germline cysts indicating that the process of germline cyst formation is conserved in the mouse.

scholarly journals Altered germline cyst and oocyte differentiation in Tex14 mutant mice reveal a new mechanism underlying female reproductive life-span

2019 ◽  
Author(s):  
Nafisa Nuzhat ◽  
Kanako Ikami ◽  
Haley Abbott ◽  
Heather Tanner ◽  
Allan C. Spradling ◽  
...  
Keyword(s):  
Germ Cells ◽  
Ovarian Function ◽  
Primordial Follicle ◽  
Wild Type ◽  
Developmental Potential ◽  
Primordial Follicles ◽  
Intercellular Bridges ◽  
Reproductive Life ◽  
Reproductive Life Span ◽  
Oocyte Differentiation

AbstractIn adult mammalian females, primordial follicles that form in the fetal/neonatal ovary are the only source to sustain adult ovarian function. Our previous studies revealed that during oocyte differentiation and primordial follicle formation in mouse fetal ovaries, primary oocytes form via gaining cytoplasm and organelles from sister germ cells that are connected to them by intercellular bridges within germline cysts. To better understand the role of intercellular bridges in oocyte differentiation, we analyzed mutant females lacking testis-expressed 14 (Tex14), a gene involved in cytokinesis and bridge formation. In Tex14-/- fetal ovaries, germ cells divide to form a reduced number of cysts in which sister germ cells are still connected via syncytia or fragmented cell membranes, rather than normal intercellular bridges. Compared with wildtype cysts, Tex14-/- cysts fragment at a higher frequency and produce a greatly reduced number of primary oocytes with highly precocious cytoplasmic enrichment and enlarged volume. By contrast, Tex14+/- germline cysts are less fragmented and generate primary oocytes that are smaller than wild type. Interestingly, enlarged Tex14-/- primary oocytes are much more stable than wild type oocytes and more efficiently sustain folliculogenesis, whereas undersized Tex14+/- primary oocytes turn over at an accelerated rate. Our observations directly link the nature of fetal germ cell connectivity to cytoplasmic enrichment during oocyte differentiation and to oocyte developmental potential in the adult ovary. Our results imply that the duration of adult ovarian function is strongly influenced by the number of primary oocytes acquiring highly enriched cytoplasm during oocyte differentiation in fetal ovaries, rather than just by the size of the primordial follicle pool.

scholarly journals TEX14 Interacts with CEP55 To Block Cell Abscission

2010 ◽  
Vol 30 (9) ◽  
pp. 2280-2292 ◽  
Author(s):  
Tokuko Iwamori ◽  
Naoki Iwamori ◽  
Lang Ma ◽  
Mark A. Edson ◽  
Michael P. Greenbaum ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Intercellular Bridge ◽  
Male Germ Cells ◽  
Physical Separation ◽  
Targeted Deletion ◽  
Intercellular Bridges ◽  
Daughter Cells ◽  
Stable Component ◽  
Evolutionarily Conserved

ABSTRACT In somatic cells, abscission, the physical separation of daughter cells at the completion of cytokinesis, requires CEP55, ALIX, and TSG101. In contrast, cytokinesis is arrested prior to abscission in differentiating male germ cells that are interconnected by TEX14-positive intercellular bridges. We have previously shown that targeted deletion of TEX14 disrupts intercellular bridges in all germ cells and causes male sterility. Although these findings demonstrate that intercellular bridges are essential for spermatogenesis, it remains to be shown how TEX14 and other proteins come together to prevent abscission and form stable intercellular bridges. Using a biochemical enrichment of male germ cell intercellular bridges, we identified additional bridge proteins, including CEP55. Although CEP55 is highly expressed in testes at the RNA level, there is no report of the presence of CEP55 in germ cells. We show here that CEP55 becomes a stable component of the intercellular bridge and that an evolutionarily conserved GPPX3Y motif of TEX14 binds strongly to CEP55 to block similar GPPX3Y motifs of ALIX and TSG101 from interacting and localizing to the midbody. Thus, TEX14 prevents the completion of cytokinesis by altering the destiny of CEP55 from a nidus for abscission to an integral component of the intercellular bridge.

scholarly journals C. elegans Anillin proteins regulate intercellular bridge stability and germline syncytial organization

2014 ◽  
Vol 206 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Rana Amini ◽  
Eugénie Goupil ◽  
Sara Labella ◽  
Monique Zetka ◽  
Amy S. Maddox ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Germ Cells ◽  
Cytoplasmic Streaming ◽  
Intercellular Bridge ◽  
Cell Specification ◽  
Intercellular Bridges ◽  
C Elegans ◽  
Daughter Cells ◽  
Germ Cell Specification

Cytokinesis generally produces two separate daughter cells, but in some tissues daughter nuclei remain connected to a shared cytoplasm, or syncytium, through incomplete cytokinesis. How syncytia form remains poorly understood. We studied syncytial formation in the Caenorhabditis elegans germline, in which germ cells connect to a shared cytoplasm core (the rachis) via intercellular bridges. We found that syncytial architecture initiates early in larval development, and germ cells become progressively interconnected until adulthood. The short Anillin family scaffold protein ANI-2 is enriched at intercellular bridges from the onset of germ cell specification, and ANI-2 loss resulted in destabilization of intercellular bridges and germ cell multinucleation defects. These defects were partially rescued by depleting the canonical Anillin ANI-1 or blocking cytoplasmic streaming. ANI-2 is also required for elastic deformation of the gonad during ovulation. We propose that ANI-2 promotes germ cell syncytial organization and allows for compensation of the mechanical stress associated with oogenesis by conferring stability and elasticity to germ cell intercellular bridges.

scholarly journals A Phosphotyrosine Switch in Estrogen Receptor β Is Required for Mouse Ovarian Function

2021 ◽  
Vol 9 ◽  
Author(s):  
Bin Yuan ◽  
Jing Yang ◽  
Louis Dubeau ◽  
Yanfen Hu ◽  
Rong Li
Keyword(s):  
Breast Cancer Cells ◽  
Target Genes ◽  
Ovarian Function ◽  
Physiological Role ◽  
Molecular Evidence ◽  
Wild Type ◽  
Female Mice ◽  
Mutant Female ◽  
And Function

The two homologous estrogen receptors ERα and ERβ exert distinct effects on their cognate tissues. Previous work from our laboratory identified an ERβ-specific phosphotyrosine residue that regulates ERβ transcriptional activity and antitumor function in breast cancer cells. To determine the physiological role of the ERβ phosphotyrosine residue in normal tissue development and function, we investigated a mutant mouse model (Y55F) whereby this particular tyrosine residue in endogenous mouse ERβ is mutated to phenylalanine. While grossly indistinguishable from their wild-type littermates, mutant female mice displayed reduced fertility, decreased ovarian follicular cell proliferation, and lower progesterone levels. Moreover, mutant ERβ from female mice during superovulation is defective in activating promoters of its target genes in ovarian tissues. Thus, our findings provide compelling genetic and molecular evidence for a role of isotype-specific ERβ phosphorylation in mouse ovarian development and function.

scholarly journals Structural and biochemical insights into the role of testis-expressed gene 14 (TEX14) in forming the stable intercellular bridges of germ cells

2015 ◽  
Vol 112 (40) ◽  
pp. 12372-12377 ◽  
Author(s):  
Hee Jung Kim ◽  
Jungbin Yoon ◽  
Atsushi Matsuura ◽  
Jung-Hyun Na ◽  
Won-Kyu Lee ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Functional Characterization ◽  
Dissociation Rate ◽  
Local Concentration ◽  
Intercellular Bridges ◽  
Endosomal Sorting ◽  
Abnormal Cells ◽  
Chimeric Peptides

Intercellular bridges are a conserved feature of spermatogenesis in mammalian germ cells and derive from arresting cell abscission at the final stage of cytokinesis. However, it remains to be fully understood how germ cell abscission is arrested in the presence of general cytokinesis components. The TEX14 (testis-expressed gene 14) protein is recruited to the midbody and plays a key role in the inactivation of germ cell abscission. To gain insights into the structural organization of TEX14 at the midbody, we have determined the crystal structures of the EABR [endosomal sorting complex required for transport (ESCRT) and ALIX-binding region] of CEP55 bound to the TEX14 peptide (or its chimeric peptides) and performed functional characterization of the CEP55–TEX14 interaction by multiexperiment analyses. We show that TEX14 interacts with CEP55-EABR via its AxGPPx3Y (Ala793, Gly795, Pro796, Pro797, and Tyr801) and PP (Pro803 and Pro804) sequences, which together form the AxGPPx3YxPP motif. TEX14 competitively binds to CEP55-EABR to prevent the recruitment of ALIX, which is a component of the ESCRT machinery with the AxGPPx3Y motif. We also demonstrate that a high affinity and a low dissociation rate of TEX14 to CEP55, and an increase in the local concentration of TEX14, cooperatively prevent ALIX from recruiting ESCRT complexes to the midbody. The action mechanism of TEX14 suggests a scheme of how to inactivate the abscission of abnormal cells, including cancer cells.

Bcl2-Associated X (BAX) Knockout in Mice Resulted in Persistence of Neonatal Testicular Germ Cells (Gonocytes)

2019 ◽  
Vol 13 (5-6) ◽  
pp. 278-285
Author(s):  
Ruili Li ◽  
Shengde Wu ◽  
Manpreet Kaur ◽  
Shan Zong ◽  
Sanduni A. Abeydeera ◽  
...  
Keyword(s):  
Stem Cells ◽  
Basement Membrane ◽  
Germ Cell ◽  
Germ Cells ◽  
Cell Counting ◽  
Testicular Development ◽  
Cell Marker ◽  
Wild Type ◽  
Anova Analysis

During early testicular development, neonatal gonocytes transform into spermatogonial stem cells (SSC), and any untransformed gonocytes are thought to undergo apoptosis. In human cryptorchidism, persisting gonocytes may lead to seminoma. Using Bcl2-associated X knockout (BAXKO) mice, we investigated apoptosis in gonocyte development during mouse minipuberty. Testes from BAXKO, heterozygous (HET), and wild-type (WT) littermates were collected on postnatal days 1, 3, 6, and 9 (<i>n</i> = 6/group), labelled with antibodies against mouse vasa homologue (MVH, germ cell marker) or promyelocytic leukaemia zinc-factor (PLZF, SSC marker) and imaged for cell counting. Total germ cells/tubule, i.e., the number of germ cells on and off the basement membrane (BM), were counted using Image J followed by 2-way ANOVA analysis with Prism. Total PLZF+ germ cells/tubule, PLZF+ germ cells/tubule off BM, total MVH+ germ cells/tubule, and MVH+ germ cells off BM/tubule were significantly higher at day 9 in BAXKO compared to WT and HET mice (<i>p </i>< 0.01). In conclusion, knockout of BAX in mouse leads to gonocytes persisting at the centre of the tubules after minipuberty, which failed to migrate and transform into SSC, indicating the important role of apoptosis is to eliminate undifferentiated gonocytes during transformation. Failed apoptosis in gonocytes may be the cause of malignancy in humans with cryptorchidism.

scholarly journals Bone abnormalities in latent TGF-β binding protein (Ltbp)-3–null mice indicate a role for Ltbp-3 in modulating TGF-β bioavailability

2002 ◽  
Vol 156 (2) ◽  
pp. 227-232 ◽  
Author(s):  
Branka Dabovic ◽  
Yan Chen ◽  
Cristina Colarossi ◽  
Hiroto Obata ◽  
Laura Zambuto ◽  
...  
Keyword(s):  
Gene Targeting ◽  
Null Mutation ◽  
Long Bones ◽  
Pathological Changes ◽  
Wild Type ◽  
Homozygous Mutant ◽  
Bone Abnormalities ◽  
Substantial Effort

The TGF-βs are multifunctional proteins whose activities are believed to be controlled by interaction with the latent TGF-β binding proteins (LTBPs). In spite of substantial effort, the precise in vivo significance of this interaction remains unknown. To examine the role of the Ltbp-3, we made an Ltbp-3–null mutation in the mouse by gene targeting. Homozygous mutant animals develop cranio-facial malformations by day 10. At 2 mo, there is a pronounced rounding of the cranial vault, extension of the mandible beyond the maxilla, and kyphosis. Histological examination of the skulls from null animals revealed ossification of the synchondroses within 2 wk of birth, in contrast to the wild-type synchondroses, which never ossify. Between 6 and 9 mo of age, mutant animals also develop osteosclerosis and osteoarthritis. The pathological changes of the Ltbp-3–null mice are consistent with perturbed TGF-β signaling in the skull and long bones. These observations give support to the notion that LTBP-3 is important for the control of TGF-β action. Moreover, the results provide the first in vivo indication for a role of LTBP in modulating TGF-β bioavailability.

alpha-spectrin is required for germline cell division and differentiation in the Drosophila ovary

Development ◽  
1996 ◽  
Vol 122 (12) ◽  
pp. 3959-3968 ◽  
Author(s):  
M. de Cuevas ◽  
J.K. Lee ◽  
A.C. Spradling
Keyword(s):  
Cyst Formation ◽  
Membrane Skeleton ◽  
Follicle Cells ◽  
Flp Recombinase ◽  
Cyst Cells ◽  
Alpha Spectrin ◽  
And Function ◽  
Oocyte Differentiation ◽  
Drosophila Ovary

During Drosophila oogenesis, developing germline cysts are spanned by a large cytoplasmic structure called a fusome, containing alpha-spectrin and the adducin-like product of the hu-li tai shao (hts) gene. We found that fusomes contain two additional membrane skeletal proteins: beta-spectrin and ankyrin. hts was shown previously to be required for cyst formation and oocyte differentiation; the role of the fusome itself, however, and the organization and function of its other components, remains unclear. Using the FRT/FLP recombinase system to generate clones of alpha-spectrin-deficient cells in the ovary, we have shown that alpha-spectrin is also required for cyst formation and oocyte differentiation, but that its role in each process is distinct from that of Hts protein. Furthermore, alpha-spectrin is required for these processes in germline cells, but not in the follicle cells that surround each cyst. We have also found that the organization of membrane skeletal proteins is more dependent on alpha-spectrin in the fusome than at the plasma membrane in other cells. Our results suggest that the fusome and its associated membrane skeleton play a central role in regulating the divisions and differentiation of cyst cells.

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