Identification of novel homologous microRNA genes in the rhesus macaque genome

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are about 22 nucleotide (nt) endogenous small RNAs that negatively regulate gene expression. They are a recently described class of regulatory molecules that has biological implications for tumorigenesis, development, metabolism and viral diseases. To date, 533 miRNAs have been identified in human. However, only 71 miRNAs have been reported in rhesus macaque. The rhesus is widely used in medical research because of its genetic and physiological similarity to human. The rhesus shares approximately 93% similarity with human in genome sequences and miRNA genes are evolutionarily conserved. Therefore, we searched the rhesus genome for sequences similar to human miRNA precursor sequences to identify putative rhesus miRNA genes.</p> <p>Results</p> <p>In addition to 71 miRNAs previously reported, we identified 383 novel miRNA genes in the rhesus genome. We compared the total 454 miRNAs identified so far in rhesus to human homologs, 173 miRNA genes showed 100% homology in precursor sequences between rhesus and human; The remaining 281 show more than 90%, less than 100% homology in precursor sequences. Some miRNAs in the rhesus genome are present as clusters similar to human, such as miR-371/373, miR-367/302b, miR-17/92, or have multiple copies distributed in the same or different chromosomes. RT-PCR analysis of expression of eight rhesus miRNA genes in rhesus tissues demonstrated tissue-specific regulation of expression.</p> <p>Conclusion</p> <p>Identification of miRNA genes in rhesus will provide the resources for analysis of expression profiles in various tissues by creating a rhesus miRNA array, which is currently not available for this species. Investigation of rhesus miRNAs will also expand our understanding of their biological function through miRNA knockout, knockdown or overexpression.</p

Primate Primordial Germ Cells Acquire Transplantation Potential by Carnegie Stage 23.

Primordial germ cells (PGCs) are the earliest embryonic progenitors in the germline. Correct formation of PGCs is critical to reproductive health as an adult. Recent work has shown that primate PGCs can be differentiated from pluripotent stem cells; however, a bioassay that supports their identity as transplantable germ cells has not been reported. Here, we adopted a xenotransplantation assay by transplanting single-cell suspensions of human and nonhuman primate embryonic Macaca mulatta (rhesus macaque) testes containing PGCs into the seminiferous tubules of adult busulfan-treated nude mice. We discovered that both human and nonhuman primate embryonic testis are xenotransplantable, generating colonies while not generating tumors. Taken together, this work provides two critical references (molecular and functional) for defining transplantable primate PGCs. These results provide a blueprint for differentiating pluripotent stem cells to transplantable PGC-like cells in a species that is amenable to transplantation and fertility studies

Fate of iPSCs Derived from Azoospermic and Fertile Men following Xenotransplantation to Murine Seminiferous Tubules

SummaryHistorically, spontaneous deletions and insertions have provided means to probe germline developmental genetics in Drosophila, mouse and other species. Here, induced pluripotent stem cell (iPSC) lines were derived from infertile men with deletions that encompass three Y chromosome azoospermia factor (AZF) regions and are associated with production of few or no sperm but normal somatic development. AZF-deleted iPSC lines were compromised in germ cell development in vitro. Undifferentiated iPSCs transplanted directly into murine seminiferous tubules differentiated extensively to germ-cell-like cells (GCLCs) that localized near the basement membrane, demonstrated morphology indistinguishable from fetal germ cells, and expressed germ-cell-specific proteins diagnostic of primordial germ cells. Alternatively, all iPSCs that exited tubules formed primitive tumors. iPSCs with AZF deletions produced significantly fewer GCLCs in vivo with distinct defects in gene expression. Findings indicate that xenotransplantation of human iPSCs directs germ cell differentiation in a manner dependent on donor genetic status

The Transition from Stem Cell to Progenitor Spermatogonia and Male Fertility Requires the SHP2 Protein Tyrosine Phosphatase

SHP2 is a widely expressed protein tyrosine phosphatase required for signal transduction from multiple cell surface receptors. Gain and loss of function SHP2 mutations in humans are known to cause Noonan and LEOPARD syndromes, respectively, that are characterized by numerous pathological conditions including male infertility. Using conditional gene targeting in the mouse, we found that SHP2 is required for maintaining spermatogonial stem cells (SSCs) and the production of germ cells required for male fertility. After deleting SHP2, spermatogenesis was halted at the initial step during which transit‐amplifying undifferentiated spermatogonia are produced from SSCs. In the absence of SHP2, proliferation of SSCs and undifferentiated spermatogonia was inhibited, thus germ cells cannot be replenished and SSCs cannot undergo renewal. However, germ cells beyond the undifferentiated spermatogonia stage of development at the time of SHP2 knockout were able to complete their maturation to become sperm. In cultures of SSCs and their progeny, inhibition of SHP2 activity reduced growth factor‐mediated intracellular signaling that regulates SSC proliferation and cell fate. Inhibition of SHP2 also decreased the number of SSCs present in culture and caused SSCs to detach from supporting cells. Injection of mice with an SHP2 inhibitor blocked the production of germ cells from SSCs. Together, our studies show that SHP2 is essential for SSCs to maintain fertility and indicates that the pathogenesis of infertility in humans with SHP2 mutations is due to compromised SSC functions that block spermatogenesis. S tem C ells 2014;32:741–753Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106124/1/stem1572.pd

Differentiation of primate primordial germ cell-like cells following transplantation into the adult gonadal niche.

A major challenge in stem cell differentiation is the availability of bioassays to prove cell types generated in vitro are equivalent to cells in vivo. In the mouse, differentiation of primordial germ cell-like cells (PGCLCs) from pluripotent cells was validated by transplantation, leading to the generation of spermatogenesis and to the birth of offspring. Here we report the use of xenotransplantation (monkey to mouse) and homologous transplantation (monkey to monkey) to validate our in vitro protocol for differentiating male rhesus (r) macaque PGCLCs (rPGCLCs) from induced pluripotent stem cells (riPSCs). Specifically, transplantation of aggregates containing rPGCLCs into mouse and nonhuman primate testicles overcomes a major bottleneck in rPGCLC differentiation. These findings suggest that immature rPGCLCs once transplanted into an adult gonadal niche commit to differentiate towards late rPGCs that initiate epigenetic reprogramming but do not complete the conversion into ENO2-positive spermatogonia

A PAX5-OCT4-PRDM1 developmental switch specifies human primordial germ cells.

Dysregulation of genetic pathways during human germ cell development leads to infertility. Here, we analysed bona fide human primordial germ cells (hPGCs) to probe the developmental genetics of human germ cell specification and differentiation. We examined the distribution of OCT4 occupancy in hPGCs relative to human embryonic stem cells (hESCs). We demonstrated that development, from pluripotent stem cells to germ cells, is driven by switching partners with OCT4 from SOX2 to PAX5 and PRDM1. Gain- and loss-of-function studies revealed that PAX5 encodes a critical regulator of hPGC development. Moreover, an epistasis analysis indicated that PAX5 acts upstream of OCT4 and PRDM1. The PAX5-OCT4-PRDM1 proteins form a core transcriptional network that activates germline and represses somatic programmes during human germ cell differentiation. These findings illustrate the power of combined genome editing, cell differentiation and engraftment for probing human developmental genetics that have historically been difficult to study

SALL4 Expression in Gonocytes and Spermatogonial Clones of Postnatal Mouse Testes

The spermatogenic lineage is established after birth when gonocytes migrate to the basement membrane of seminiferous tubules and give rise to spermatogonial stem cells (SSC). In adults, SSCs reside within the population of undifferentiated spermatogonia (Aundiff) that expands clonally from single cells (Asingle) to form pairs (Apaired) and chains of 4, 8 and 16 Aaligned spermatogonia. Although stem cell activity is thought to reside in the population of Asingle spermatogonia, new research suggests that clone size alone does not define the stem cell pool. The mechanisms that regulate self-renewal and differentiation fate decisions are poorly understood due to limited availability of experimental tools that distinguish the products of those fate decisions. The pluripotency factor SALL4 (sal-like protein 4) is implicated in stem cell maintenance and patterning in many organs during embryonic development, but expression becomes restricted to the gonads after birth. We analyzed the expression of SALL4 in the mouse testis during the first weeks after birth and in adult seminiferous tubules. In newborn mice, the isoform SALL4B is expressed in quiescent gonocytes at postnatal day 0 (PND0) and SALL4A is upregulated at PND7 when gonocytes have colonized the basement membrane and given rise to spermatogonia. During steady-state spermatogenesis in adult testes, SALL4 expression overlapped substantially with PLZF and LIN28 in Asingle, Apaired and Aaligned spermatogonia and therefore appears to be a marker of undifferentiated spermatogonia in mice. In contrast, co-expression of SALL4 with GFRα1 and cKIT identified distinct subpopulations of Aundiff in all clone sizes that might provide clues about SSC regulation. Collectively, these results indicate that 1) SALL4 isoforms are differentially expressed at the initiation of spermatogenesis, 2) SALL4 is expressed in undifferentiated spermatogonia in adult testes and 3) SALL4 co-staining with GFRα1 and cKIT reveals distinct subpopulations of Aundiff spermatogonia that merit further investigation. © 2013 Gassei, Orwig

Multiresolution identification of germ layer components in teratomas derived from human and nonhuman primate embryonic stem cells

We propose a system for identification of germ layer components in teratomas derived from human and nonhuman primate embryonic stem cells. Tissue regeneration and repair, drug testing and discov-ery, the cure of genetic and developmental syndromes all may rest on the understanding of the biology and behavior of embryonic stem (ES) cells. Within the field of stem cell biology, an ES cell is not con-sidered an ES cell until it can produce a teratoma tumor (the ”gold” standard test); a seemingly disorganized mass of tissue derived from all three embryonic germ layers; ectoderm, mesoderm, and endo-derm. Identification and quantification of tissue types within ter-atomas derived from ES cells may expand our knowledge of abnor-mal and normal developmental programming and the response of ES cells to genetic manipulation and/or toxic exposures. In addition, because of the tissue complexity, identifying and quantifying the tis-sue is tedious and time consuming, but in turn the teratoma provides an excellent biological platform to test robust image analysis algo-rithms. We use a multiresolution (MR) classification system with texture features, as well as develop novel nuclear texture features to recognize germ layer components. With redundant MR transform, we achieve a classification accuracy of approximately 88%. Index Terms — Stem cell biology, multiresolution, classifica-tion, feature extractio

Differences in gonadal tissue cryopreservation practices for differences of sex development across regions in the United States

ObjectiveSome individuals with differences of sex development (DSD) conditions undergo medically indicated prophylactic gonadectomy. Gonads of individuals with DSD can contain germ cells and precursors and patients interested in future fertility preservation and hormonal restoration can participate in DSD-specific research protocols to cryopreserve this tissue. However, it is unclear how many providers or institutions offer gonadal tissue cryopreservation (GTC) and how widespread GTC for DSD is across the United States (US). The Pediatric Initiative Network (PIN) and Non-Oncologic Conditions committees of the Oncofertility Consortium sought to assess the current state of GTC for patients with DSD.MethodsAn electronic survey was sent to providers caring for patients with DSD via special interest groups of professional societies and research networks.ResultsThe survey was administered between November 15, 2021 and March 14, 2022. A total of 155 providers responded to the survey, of which 132 respondents care for patients with DSD, and 78 work at facilities that offer medically indicated gonadectomy to patients with DSD diagnoses. They represented 55 US institutions including 47 pediatric hospitals, and 5 international sites (Canada, Denmark, Germany, Qatar). Of individual providers, 41% offer cryopreservation after prophylactic gonadectomy for patients with DSD (32/78). At an institutional level, GTC after medically indicated gonadectomy is available at 54.4% (24/46) of institutions. GTC is offered for a variety of DSD diagnoses, most commonly 45,X/46,XY DSD (i.e., Turner Syndrome with Y-chromosome material and mixed gonadal dysgenesis), ovotesticular DSD, complete androgen insensitivity syndrome (CAIS), and complete gonadal dysgenesis. Responses demonstrate regional trends in GTC practices with 83.3% of institutions in the Midwest, 66.7% in the Northeast, 54.6% in the West, and 35.3% in the South providing GTC. All represented institutions (100%) send gonadal tissue for pathological evaluation, and 22.7% preserve tissue for research purposes.ConclusionsGTC after gonadectomy is offered at half of the US institutions represented in our survey, though a minority are currently preserving tissue for research purposes. GTC is offered for several DSD conditions. Future research will focus on examining presence and quality of germ cells to support clinical decision making related to fertility preservation for patients with DSD