Medical Cell Biology Commons^™

Telomerase Reverse Transcriptase In Atherosclerosis, Hua Qing

Theses and Dissertations--Pharmacology and Nutritional Sciences

Telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase and the limiting factor for the enzyme activity. The expression of TERT and telomerase activity is increased in atherosclerotic plaques. However, the role of TERT dysregulation during atherosclerosis formation remains unknown.

The work herein first identified a multi-tiered regulation of TERT expression in smooth muscle cells (SMC) through histone deacetylase (HDAC) inhibition. HDAC inhibition induces TERT transcription and promoter activation. At the protein level in contrast, HDAC inhibition decreases TERT protein abundance through enhanced degradation, which decreases telomerase activity and induces senescence. Furthermore, during vascular remodeling in vivo, TERT protein …

Decellularized Wharton's Jelly From Human Umbilical Cord As A Novel 3d Scaffolding Material For Tissue Engineering Applications., Sushma Jadalannagari, Gabriel Converse, Eric Buse, Michael Filla, Maria T. Villar, Antonio Artigues, Adam J. Mellot, Jinxi Wang, Michael S. Detamore, Richard A. Hopkins, Omar S. Aljitawi, C Mcfall

Manuscripts, Articles, Book Chapters and Other Papers

In tissue engineering, an ideal scaffold attracts and supports cells thus providing them with the necessary mechanical support and architecture as they reconstruct new tissue in vitro and in vivo. This manuscript details a novel matrix derived from decellularized Wharton's jelly (WJ) obtained from human umbilical cord for use as a scaffold for tissue engineering application. This decellularized Wharton's jelly matrix (DWJM) contained 0.66 ± 0.12 μg/mg sulfated glycosaminoglycans (GAGs), and was abundant in hyaluronic acid, and completely devoid of cells. Mass spectroscopy revealed the presence of collagen types II, VI and XII, fibronectin-I, and lumican I. When seeded onto …

Characterization Of The Role Of Insulin-Like Growth Factor Binding Protein 7 (Igfbp7) Using A Genetic Knockout Mouse Model, Maaged A. Akiel

Theses and Dissertations

In the US, the incidence and mortality rates of hepatocellular carcinoma (HCC) are alarmingly increasing since no effective therapy is available for the advanced disease. Activation of IGF signaling is a major oncogenic event in diverse cancers, including HCC. Insulin-like growth factor binding protein-7 (IGFBP7) inhibits IGF signaling by binding to IGF-1 receptor (IGF-1R) and functions as a potential tumor suppressor for hepatocellular carcinoma (HCC). IGFBP7 abrogates tumors by inducing cancer-specific senescence and apoptosis and inhibiting angiogenesis. We now document that Igfbp7 knockout (Igfbp7-/- ) mouse shows constitutive activation of IGF signaling, presents with pro-inflammatory and immunosuppressive microenvironment, and develops …

Yap And The Hippo Pathway In Pediatric Cancer., Atif Ahmed, Abdalla D. Mohamed, Melissa Gener, Weijie Li, Eugenio Taboada

Manuscripts, Articles, Book Chapters and Other Papers

The Hippo pathway is an important signaling pathway that controls cell proliferation and apoptosis. It is evolutionarily conserved in mammals and is stimulated by cell-cell contact, inhibiting cell proliferation in response to increased cell density. During early embryonic development, the Hippo signaling pathway regulates organ development and size, and its functions result in the coordinated balance between proliferation, apoptosis, and differentiation. Its principal effectors, YAP and TAZ, regulate signaling by the embryonic stem cells and determine cell fate and histogenesis. Dysfunction of this pathway contributes to cancer development in adults and children. Emerging studies have shed light on the upregulation …

Role Of Translation Initiation In Regulation Of Epithelial Junctions And Cell Motility, Fahda Fawaz Alsharief

Theses and Dissertations

The integrity and barrier properties of intestinal epithelium are determined by specialized adhesive structures known as intercellular junctions; composed of adherens junctions (AJs), tight junctions (TJs) and focal adhesions that mediate cell-cell and cell matrix interactions, respectively. These two types of epithelial cell adhesions regulate each other during disruption and restitution of the epithelial barrier. Inflammatory cytokines such as interferon gamma (IFNγ) and tumor necrosis factor alpha (TNFα) are elevated during intestinal inflammation. The most notable effects of IFNγ and TNFα on intestinal epithelial homeostasis involve disruption of apical junctions and attenuation of cell migration. Although molecular mechanisms underlying these …

Comparative Genetic Screens In Human Cells Reveal New Regulatory Mechanisms In Wnt Signaling, Andres M. Lebensohn, Ramin Dubey, Leif Neitzel, Ofelia Tacchelly-Benites

Dartmouth Scholarship

The comprehensive understanding of cellular signaling pathways remains a challenge due to multiple layers of regulation that may become evident only when the pathway is probed at different levels or critical nodes are eliminated. To discover regulatory mechanisms in canonical WNT signaling, we conducted a systematic forward genetic analysis through reporter-based screens in haploid human cells. Comparison of screens for negative, attenuating and positive regulators of WNT signaling, mediators of R-spondin-dependent signaling and suppressors of constitutive signaling induced by loss of the tumor suppressor adenomatous polyposis coli or casein kinase 1α uncovered new regulatory features at most levels of the …

Calcium Uptake Hotspots In The Mitochondria Of Cardiac Muscle At The Interface With Dyadic Sr, Sergio De La Fuente, Celia Fernandez-Sanz, Caitlin Vail, Elorm J. Agra, Kira Holmstrom, Junhui Sun, Jyotsna Mishra, Toren Finkel, Elizabeth Murphy, Suresh K. Joseph, Shey-Shing Sheu, György Csordás

Department of Pathology, Anatomy, and Cell Biology Posters

Introduction

• Control of the mitochondrial ATP production by SR-derived Ca2+ signals includes local, nanodomain Ca2+ transfer from ryanodine receptors (RyR2) to the mitochondrial matrix (excitation-bioenergetics coupling).

• Ca2+ crosses the inner mitochondrial membrane (IMM) via the mtCU, a low-affinity Ca2+-activated Ca2+ channel complex.

• The surface area of cardiac IMM is extensively enhanced by cristae folding; however, mitoplast patch clamp studies showed mtCU current density the lowest amongst a range of tissues (Fieni 2012. Nat Commun).

Retinal Ganglion Cell Neuroprotection Induced By Neuropharmacological Agents In An In-Vivo Model Of Glaucoma, Quinn Ameel

Honors Theses

Recent discoveries from this lab have demonstrated that activation of alpha7 nicotinic acetylcholine receptors (α7 nAChRs) on retinal ganglion cells (RGCs) in the retina is linked to neuroprotection of RGCs that are typically lost in glaucoma-like conditions. Various chemical agents have been produced to increase overall neurotransmission of ACh from cholinergic neurons. DMP-543 is an agent that increases calcium release from cholinergic synaptic terminals. Donepezil is an acetylcholinesterase inhibitor that inhibits the breakdown of ACh in the synaptic cleft, prolonging ACh’s effect. In this study, the neuroprotective activity of these two agents was analyzed at the synapse between starburst amacrine …

An Examination Into The Relationship Between Iron Deficiency And Postpartum Depression, Sara A. Burroughs

Senior Honors Theses

Postpartum depression is recognized as the most common complication of childbearing; however, its etiology remains fairly undetermined. Many different influences have been hypothesized as to what may cause postpartum depression, including changes in levels of various hormones (such as estrogen and progesterone), a decrease in serotonin, low levels of vitamin D, social factors, and iron deficiency. The lack of strong evidence for one specific cause makes it fairly clear that there are many factors that play a role in the development of postpartum depression. Iron deficiency is one issue that is thought to contribute to the development of postpartum depression …

Environmental Signaling Through The Target Of Rapamycin Complex 1 (Torc1) And The Regulation Of Epigenetic Mechanisms, Jason J. Workman

Theses and Dissertations (ETD)

The gene expression profile of a eukaryotic cell is responsive to a variety of extracellular stimuli, including nutrient availability, which allows cells to toggle between anabolism and catabolism based on the favorability of their environment. Much of this information is relayed through signaling complexes, such as the target of rapamycin complex 1 (TORC1), to downstream chromatin modifying enzymes. These enzymes impact the gene regulatory process through altered histone post-translation modifications, changes in chromatin structure, and docking of chromatin regulatory complexes. Yet, despite preliminary studies suggesting that TORC1 affects epigenetic mechanisms, including histone H3 lysine 56 acetylation (H3K56ac), almost nothing is …

Role Of Occludin In The Regulation Of Epithelial Tight Junctions, Bhargavi Manda

Theses and Dissertations (ETD)

Tight junctions (TJ) constitute the primary component of epithelial barrier function, a disruption of which is involved in the pathogenesis of many gastrointestinal, pulmonary and renal diseases. Occludin is the major transmembrane protein of TJ, a deletion of which leads to a complex phenotype including chronic inflammation in several epithelial tissues of occludin deficient mice and poor TJ integrity in epithelial cell lines. Its down regulation was seen in Crohn’s disease, tumors of the colon, brain, endometrium and breast cancer. Occludin is also known to be a target that enables Hepatitis C Virus infection and bacterial pathogenesis. But the specific …

The Nucleolar Protein Nucleophosmin Undergoes Liquid-Liquid Phase Separation With Arginine-Rich Nucleolar Proteins Through Weak, Multivalent Electrostatic Interactions, Jaclyn Alicia Cika

Theses and Dissertations (ETD)

Nucleoli are nuclear membrane-less organelles that are the sites for ribosome biogenesis and serve as sensors of cellular stress. Weak, multivalent protein-protein interactions and interactions between disordered, low complexity domains (LCDs) and rRNA have been shown to promote liquid-liquid phase separation (LLPS) in vitro, suggesting a basis for the liquid-like behavior of nucleoli. Nucleophosmin (NPM1), a multifunctional and highly abundant nucleolar protein, exhibits structural features associated with LLPS suggesting a role in nucleolar organization. Specifically, NPM1 forms a pentamer through its N-terminal oligomerization domain and can bind to rRNA through its C-terminal nucleic acid binding domain. Multiple acidic tracts throughout …

The Influence Of Age On The Diagnostic Performance Of White Blood Cell Count And Absolute Neutrophil Count In Suspected Pediatric Appendicitis., Richard G. Bachur, Peter S. Dayan, Nanette C. Dudley, Lalit Bajaj, Michelle D. Stevenson, Charles G. Macias, Manoj K. Mittal, Jonathan Bennett, Kelly A. Sinclair, Michael C. Monuteaux, Anupam B. Kharbanda

Manuscripts, Articles, Book Chapters and Other Papers

OBJECTIVE: White blood cell (WBC) count and absolute neutrophil count (ANC) are a standard part of the evaluation of suspected appendicitis. Specific threshold values are utilized in clinical pathways, but the discriminatory value of WBC count and ANC may vary by age. The objective of this study was to investigate whether the diagnostic value of WBC count and ANC varies across age groups and whether diagnostic thresholds should be age-adjusted.

METHODS: This is a multicenter prospective observational study of patients aged 3-18 years who were evaluated for appendicitis. Receiver operator characteristic curves were developed to assess overall discriminative power of …

Single-Cell Transcriptional Analysis Reveals Novel Neuronal Phenotypes And Interaction Networks Involved In The Central Circadian Clock., James Park, Haisun Zhu, Sean O'Sullivan, Babatunde A Ogunnaike, David R Weaver, James S. Schwaber, Rajanikanth Vadigepalli

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Single-cell heterogeneity confounds efforts to understand how a population of cells organizes into cellular networks that underlie tissue-level function. This complexity is prominent in the mammalian suprachiasmatic nucleus (SCN). Here, individual neurons exhibit a remarkable amount of asynchronous behavior and transcriptional heterogeneity. However, SCN neurons are able to generate precisely coordinated synaptic and molecular outputs that synchronize the body to a common circadian cycle by organizing into cellular networks. To understand this emergent cellular network property, it is important to reconcile single-neuron heterogeneity with network organization. In light of recent studies suggesting that transcriptionally heterogeneous cells organize into distinct cellular …

Mirna-145 Increases Therapeutic Sensibility To Gemcitabine Treatment Of Pancreatic Adenocarcinoma Cells., Yong Lin, Xin Ge, Yiyang Wen, Zhu-Mei Shi, Qiu-Dan Chen, Min Wang, Ling-Zhi Liu, Bing-Hua Jiang, Yuan Lu

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Pancreatic adenocarcinoma is one of the most leading causes of cancer-related deaths worldwide. Although recent advances provide various treatment options, pancreatic adenocarcinoma has poor prognosis due to its late diagnosis and ineffective therapeutic multimodality. Gemcitabine is the effective first-line drug in pancreatic adenocarcinoma treatment. However, gemcitabine chemoresistance of pancreatic adenocarcinoma cells has been a major obstacle for limiting its treatment effect. Our study found that p70S6K1 plays an important role in gemcitabine chemoresistence. MiR-145 is a tumor suppressor which directly targets p70S6K1 for inhibiting its expression in pancreatic adenocarcinoma, providing new therapeutic scheme. Our findings revealed a new mechanism underlying …

Peroxiredoxin Catalysis At Atomic Resolution, Arden Perkins, Derek Parsonage, Kimberly J. Nelson, O. Maduka Ogba, Paul Ha-Yeon Cheong, Leslie B. Poole, P. Andrew Karplus

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Peroxiredoxins (Prxs) are ubiquitous cysteine-based peroxidases that guard cells against oxidative damage, are virulence factors for pathogens, and are involved in eukaryotic redox regulatory pathways. We have analyzed catalytically active crystals to capture atomic resolution snapshots of a PrxQ-subfamily enzyme (from Xanthomonas campestris) proceeding through thiolate, sulfenate, and sulfinate species. These analyses provide structures of unprecedented accuracy for seeding theoretical studies, and show novel conformational intermediates giving insight into the reaction pathway. Based on a highly non-standard geometry seen for the sulfenate intermediate, we infer that the sulfenate formation itself can strongly promote local unfolding of the active site to …

Ehd1 As A Positive Regulator Of Macrophage Colony-Stimulating Factor-1 Receptor, Luke R. Cypher

Theses & Dissertations

The master regulator of the macrophage development, differentiation, proliferation, survival, phagocytosis, cytokine secretion, motility, adhesion, migration, and spreading is the receptor tyrosine kinase (RTK) colony stimulating factor-1 receptor (CSF-1R). Aberrant CSF-1R signaling is present amongst a variety of highly prevalent and devastating human diseases in the United States such as atherosclerosis, cancer, inflammatory bowel disease, arthritis, and neuro-demyelination/neuro-degeneration. A better understanding of basic mechanisms that govern macrophage development and function is of vital importance in treating patients afflicted with these conditions/diseases. CSF-1R presentation on the macrophage cell surface is a required precursor for CSF1- induced RTK dimerization (activation) and downstream …

Integrated Live Imaging And Molecular Profiling Of Embryoid Bodies Reveals A Synchronized Progression Of Early Differentiation., Jonathan Boxman, Naor Sagy, Sirisha Achanta, Rajanikanth Vadigepalli, Iftach Nachman

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Embryonic stem cells can spontaneously differentiate into cell types of all germ layers within embryoid bodies (EBs) in a highly variable manner. Whether there exists an intrinsic differentiation program common to all EBs is unknown. Here, we present a novel combination of high-throughput live two-photon imaging and gene expression profiling to study early differentiation dynamics spontaneously occurring within developing EBs. Onset timing of Brachyury-GFP was highly variable across EBs, while the spatial patterns as well as the dynamics of mesendodermal progression following onset were remarkably similar. We therefore defined a 'developmental clock' using the Brachyury-GFP signal onset timing. Mapping snapshot …

Activated Clotting Time (Act): Comparison Of The Hemochron Signature Elite And The Abbott I-Stat, Lilah Evans, Susanne Gallo, Joseph J. Leo, Barbara Goldsmith, Phd, Facb

Department of Pathology, Anatomy, and Cell Biology Posters

BACKGROUND

ACT is commonly used for heparin anticoagulation monitoring during procedures including cardiopulmonary bypass surgery, coronary angioplasty, and interventional radiology. To prevent thrombosis, moderate to high levels of heparin anticoagulation are required. The Hemochron Signature Elite (HSE, Accriva Diagnostics, formerly ITC, San Diego, CA) was implemented at TJUH as a replacement for the older model Hemochron Response (Accriva/ITC Model HRS.110, San Diego, CA). Operating room (OR) perfusionists reported irreproducible high results using HSE that could not be explained clinically. In consideration of use of i-STAT analyzers (Abbott Point of Care, Princeton, NJ) as an alternative to HSE, we performed a …

Performance Of Creatinine And Chloride On The Epoc Analyzer, Lilah Evans, Susanne Gallo, Stacey K. Mardekian, Barbara Goldsmith, Phd, Facb

Department of Pathology, Anatomy, and Cell Biology Posters

BACKGROUND

The epoc Blood Analysis System (Alere, Orlando, FL) performs blood gases, electrolytes, and metabolites using a Blood Gas Electrolyte and Metabolite (BGEM) Test Card panel on 92 uL of whole blood. The BGEM test card uses potentiometric sensors to measure sodium, potassium, ionized calcium, pH, pCO2; amperometric sensors to measure pO2, glucose, and lactate; and a conductometric sensor to measure hematocrit. Results are available in 3-10 minutes, depending upon the time between calibration and patient testing. TJUH implemented the epoc in its ICUs in 2012 to provide Point of Care (POC) results. Alere recently added creatinine and chloride sensors …

The Role Of E. Coli Transcript-Cleavage Factors Gre In Transcriptional Regulation Under Hyperosmotic Stress, Kseniya Obraztsova

Graduate School of Biomedical Sciences Theses and Dissertations

Escherichia coli adapts to changes in the osmotic environment through the process of osmotic response which entails synthesis of specific enzymes and transporters to accumulate essential osmoprotectants. This process is highly regulated at the level of transcription. Upon cell exposure to high salt, RNA polymerase (RNAP} rapidly dissociates from genomic DNA, while the nucleoid becomes hyper condensed. During the subsequent osmoadaptation phase RNAP reassociates with the DNA and resumes transcription. The mechanisms of transcription initiation, promoter escape and its regulation during osmoadaptation are poorly understood. Here we demonstrate that a highly conserved bacterial regulator, transcript cleavage factor GreA, is essential …

The Genetic Hierarchy Of The Heterochronic Pathway In C. Elegans, Jennifer Tsialikas

Graduate School of Biomedical Sciences Theses and Dissertations

The correct timing of developmental events is fundamental to the growth of every animal. The pathways that control developmental timing and cell-fate succession are complex and robust in a way that underscores this importance. In this work, I have shown how an early developmental regulator, LIN-14, acts to integrate the earliest aspects of development with the events that take place afterward. I have uncovered how microRNAs from two different families fit into the cascade of proteins and micro RNA regulation that defines the developmental timing pathway. Finally, my work has helped to uncover the dual-acting nature of two proteins in …

The Role Of Neurovascular Compromise, Autoimmune Antibodies And Neuronal Calcium Sensor Proteins During The Onset And Progression Of Alzheimer's Disease - Linking The Retina With The Brain, Hao Wu

Graduate School of Biomedical Sciences Theses and Dissertations

Alzheimer's disease (AD), the main cause of dementia, is a progressive and irreversible neurodegenerative disease. The pathological hallmarks of the disease include bloodbrain barrier (BBB) breach, neurofibrillary tang les and amyloid plaques. Also, emerging evidence has raised the possibility that instead of a secondary consequence, the neuroinflammation contributes to the development and early progression of AD. However, the mechanism underlying the blood-neural barrier (BNB), chronic inflammation and neuronal degenerative diseases (NDDs) remain to be elucidated.

To explore the role of the chronic inflammation in NDDs and delineate the early steps of these diseases, in vivo drug-induced and transgenic mouse models …

Reduced Motor Neuron Excitability Is An Important Contributor To Weakness In A Rat Model Of Sepsis, Paul Nardelli, Jacob A. Vincent, Randall K. Powers, Timothy C. Cope, Mark M. Rich

Neuroscience, Cell Biology & Physiology Faculty Publications

The mechanisms by which sepsis triggers intensive care unit acquired weakness (ICUAW) remain unclear. We previously identified difficulty with motor unit recruitment in patients as a novel contributor to ICUAW. To study the mechanism underlying poor recruitment of motor units we used the rat cecal ligation and puncture model of sepsis. We identified striking dysfunction of alpha motor neurons during repetitive firing. Firing was more erratic, and often intermittent. Our data raised the possibility that reduced excitability of motor neurons was a significant contributor to weakness induced by sepsis. In this study we quantified the contribution of reduced motor neuron …

Regulation Of Breast Cancer Initiation And Progression By 14-3-3zeta, Chia-Chi Chang

Dissertations and Theses (Open Access)

14-3-3ζ is a ubiquitously expressed family member of proteins that have been implicated to have oncogenic potential through its interactions and involvement in cancer initiation and progression. 14-3-3ζ belongs to the highly conserved 14-3-3ζ protein family and modulates numerous pathways in cancer. Overexpression of 14-3-3ζ is an early event, occurs in more than 40% of human breast cancer cases, and is associated with disease recurrence and poor prognosis. Metabolic reprogramming is a hallmark of cancer. Cancer cells elevate aerobic glycolysis to produce metabolic intermediates and reducing equivalents, thereby facilitating cellular adaptation to the adverse environment and sustaining fast proliferation. Interestingly, …

The Roles Of Nuclear Receptor Nr4a1 In Cancer Cell Proliferation And Skeletal Muscle Differentiation, Alexa Farmer

Theses and Dissertations (ETD)

Nuclear receptors (NRs) constitute a major class of drug targets in the treatment of various cancer types. NRs respond to cellular signals and become activated upon ligand binding to transcriptionally modulate expression of target genes. NR4A1 (Nur77) is a member of the NR4A family of nuclear receptors and displays an oncogenic profile in many cancer models. It is often upregulated in adult solid malignancies and is known to promote cell proliferation and survival. Knockdown studies of NR4A1 in cancer cell lines results in decreased cell growth and angiogenesis and increased apoptosis, suggesting NR4A1 is an oncogenic protein. Due to the …

Development Of Rational Combination Therapy With Parp Inhibitors And Kinase Inhibitors In Tnbc, Wen-Hsuan Yu

Dissertations and Theses (Open Access)

Poly (ADP-ribose) polymerase inhibitors (PARPi) emerge as potential targeting drugs for BRCA-deficient cancers including triple negative breast cancer (TNBC). However, it has been reported that a subgroup of patients even with BRCA mutation fails to respond to PARPi in multiple clinical trials. In this study, we identified c-Met, a tyrosine kinase, phosphorylates PARP1 at Y907 and that the phosphorylation increases PARP1 activity, thereby rendering cancer cells resistant to PARPi. The combination of c-Met inhibitors (METi) and PARPi has a synergistic effect for c-Met overexpressed TNBC in vitro and in vivo. In addition to c-Met, through functional analysis, we found …

Exome-Based Variant Detection In Core Promoters., Yeong C. Kim, Jian Cui, Jiangtao Luo, Fengxia Xiao, Bradley Downs, San Ming Wang

Journal Articles: Genetics, Cell Biology & Anatomy

Core promoter controls the initiation of transcription. Core promoter sequence change can disrupt transcriptional regulation, lead to impairment of gene expression and ultimately diseases. Therefore, comprehensive characterization of core promoters is essential to understand normal and abnormal gene expression in biomedical studies. Here we report the development of EVDC (Exome-based Variant Detection in Core promoters) method for genome-scale analysis of core-promoter sequence variation. This method is based on the fact that exome sequences contain the sequences not only from coding exons but also from non-coding region including core promoters generated by random fragmentation in exome sequencing process. Using exome data …

Cytojournal Quiz Cases: Publishing Open-Access, Pubmed-Searchable Cytopathology Cases With Educational Messages, Katherine G. Akers, Vinod B. Shidham

Library Scholarly Publications

No abstract provided.

Microrna-Target Interactions In Embryonic Stem Cells, Shuang Wu

Graduate School of Biomedical Sciences Theses and Dissertations

Animal embryogenesis is a highly orchestrated process involving many geneexpression programs that determine specific fates of individual cells during development. Gene expression can be regulated at different stages such as at transcription initiation or mRNA stability, and microRNA-mediated gene regulation is a crucial pathway on the regulation of mRNA stability. microRNAs, or miRNAs, are small, conserved non-coding RNAs that negatively regulate gene expression post-transcriptionally. The mouse miR-290-295 cluster and its human homolog miR-371-373 are stem cell-specific miRNA clusters, and their expression can only be observed in early embryos, primordial germ cells, germ cell compartments of adult testis and embryonic stem …