Mouse CHD4-NURD is Required for Neonatal Spermatogonia Survival and Normal Gonad Development.

Testis development and sustained germ cell production in adults rely on the establishment and maintenance of spermatogonia stem cells and their proper differentiation into spermatocytes. Chromatin remodeling complexes regulate critical processes during gamete development by restricting or promoting accessibility of DNA repair and gene expression machineries to the chromatin. Here, we investigated the role of CHD4 and CHD3 catalytic subunits of the NURD complex during spermatogenesis. Germ cell-specific deletion of Chd4 early in gametogenesis, but not Chd3, resulted in arrested early gamete development due to failed cell survival of neonate undifferentiated spermatogonia stem cell population. Candidate assessment revealed that CHD4 controls expression of Dmrt1 and its downstream target Plzf, both described as prominent regulators of spermatogonia stem cell maintenance. Our results show the requirement of CHD4 in mammalian gametogenesis pointing to functions in gene expression early in the process.

PIWIL1 Drives Chemoresistance in Multiple Myeloma by Modulating Mitophagy and the Myeloma Stem Cell Population

As an important member of the Argonaute protein family, PIWI-like protein 1 (PIWIL1) plays a key role in tumor cell viability. However, the exact function of PIWIL1 in multiple myeloma (MM) and the underlying mechanism remain unclear. Here, we revealed that PIWIL1 was highly expressed in myeloma cell lines and newly diagnosed MM patients, and that its expression was notably higher in refractory/relapsed MM patients. PIWIL1 promoted the proliferation of MM cells and conferred resistance to chemotherapeutic agents both in vitro and in vivo. More importantly, PIWIL1 enhanced the formation of autophagosomes, especially mitophagosomes, by disrupting mitochondrial calcium signaling and modulating mitophagy-related canonical PINK1/Parkin pathway protein components. Mitophagy/autophagy inhibitors overcome PIWIL1-induced chemoresistance. In addition, PIWIL1 overexpression increased the proportion of side population (SP) cells and upregulated the expression of the stem cell-associated genes Nanog, OCT4, and SOX2, while its inhibition resulted in opposite effects. Taken together, our findings demonstrated that PIWIL1 induced drug resistance by activating mitophagy and regulating the MM stem cell population. PIWIL1 depletion significantly overcame drug resistance and could be used as a novel therapeutic target for reversing resistance in MM patients.

Hindlimb Immobilization Increases IL-1β and Cdkn2a Expression in Skeletal Muscle Fibro-Adipogenic Progenitor Cells: A Link Between Senescence and Muscle Disuse Atrophy

Loss of muscle mass and strength contributes to decreased independence and an increased risk for morbidity and mortality. A better understanding of the cellular and molecular mechanisms underlying muscle atrophy therefore has significant clinical and therapeutic implications. Fibro-adipogenic progenitors (FAPs) are a skeletal muscle resident stem cell population that have recently been shown to play vital roles in muscle regeneration and muscle hypertrophy; however, the role that these cells play in muscle disuse atrophy is not well understood. We investigated the role of FAPs in disuse atrophy in vivo utilizing a 2-week single hindlimb immobilization model. RNA-seq was performed on FAPs isolated from the immobilized and non-immobilized limb. The RNAseq data show that IL-1β is significantly upregulated in FAPs following 2 weeks of immobilization, which we confirmed using droplet-digital PCR (ddPCR). We further validated the RNA-seq and ddPCR data from muscle in situ using RNAscope technology. IL-1β is recognized as a key component of the senescence-associated secretory phenotype, or SASP. We then tested the hypothesis that FAPs from the immobilized limb would show elevated senescence measured by cyclin-dependent kinase inhibitor 2A (Cdkn2a) expression as a senescence marker. The ddPCR and RNAscope data both revealed increased Cdkn2a expression in FAPs with immobilization. These data suggest that the gene expression profile of FAPs is significantly altered with disuse, and that disuse itself may drive senescence in FAPs further contributing to muscle atrophy.

Fractional order modeling and analysis of dynamics of stem cell differentiation in complex network

<abstract><p>In this study, a mathematical model for the differentiation of stem cells is proposed to understand the dynamics of cell differentiation in a complex network. For this, myeloid cells, which are differentiated from stem cells, are introduced in this study. We introduce the threshold quantity $ \mathcal{R}_{0} $ to understand the population dynamics of stem cells. The local stability analysis of three equilibria, namely $ (i) $ free equilibrium points, $ (ii) $ absence of stem and progenitor cells, and $ (iii) $ endemic equilibrium points are investigated in this study. The model is first formulated in non-fractional order and after that converted into a fractional sense by utilizing the Atangana-Baleanu derivative in Caputo (ABC) sense in the form of a non-singular kernel. The model is solved by using numerical techniques. It is seen that the myeloid cell population significantly affects the stem cell population.</p></abstract>

Growth Inhibitory Efficacy of Chinese Herbs in a Cellular Model for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is characterized by the absence of estrogen receptor-α progesterone receptor and human epidermal growth factor receptor-2. Treatment for this breast cancer subtype is restricted to multidrug chemotherapy and survival pathway-based molecularly targeted therapy. The long-term treatment options are associated with systemic toxicity, spontaneous and/or acquired tumor resistance and the emergence a of drug-resistant stem cell population. These limitations lead to advanced stage metastatic cancer. Current emphasis is on research directions that identify efficacious, naturally occurring agents representing an unmet need for testable therapeutic alternatives for therapy resistant breast cancer. Chinese herbs are widely used in traditional Chinese medicine in women for estrogen related health issues and also for integrative support for cancer treatment. This review discusses published evidence on a TNBC model for growth inhibitory effects of several mechanistically distinct nontoxic Chinese herbs, most of them nutritional in nature, and identifies susceptible pathways and potential molecular targets for their efficacy. Documented anti-proliferative and pro-apoptotic effects of these herbs are associated with downregulation of RB, RAS, PI3K, and AKT signaling, modulation of Bcl-2/BAX protein expressions and increased caspase activity. This review provides a proof of concept for Chinese herbs as testable alternatives for prevention/therapy of TNBC.

Glioblastoma embryonic-like stem cells exhibit immune-evasive phenotype

Glioma stem cells (GSCs) are a subset of cells with self-renewal and tumor-initiating capacities that are thought to participate in drug resistance and immune evasion mechanisms in glioblastoma (GBM). Given GBM heterogeneity, we hypothesized that GSCs might also display cellular hierarchies associated with different degrees of stemness. We evaluated a single-cell RNA-seq glioblastoma dataset (n = 28) and identified a stem cell population co-expressing high levels of embryonic pluripotency markers, named core glioma stem cells (c-GSCs). This embryonic-like population represents 4.22% of the tumor cell mass, and pathway analysis revealed an upregulation of stemness and downregulation of immune-associated pathways. Using induced pluripotent stem cell technology, we generated an in vitro model of c-GSCs by reprogramming glioblastoma patient-derived cells into induced c-GSCs (ic-GSCs). Immunostaining of ic-GSCs showed high expression of embryonic pluripotency markers and downregulation of antigen presentation HLA proteins, mimicking its tumoral counterpart. Transcriptomic analysis revealed a strong agreement of enriched biological pathways between tumor c-GSCs and in vitro ic-GSCs (k = 0.71). Integration of ic-GSC DNA methylation and gene expression with chromatin state analysis of epigenomic maps (n = 833) indicated that polycomb repressive marks downregulate HLA genes in stem-like phenotype. Together, we identified c-GSCs as a GBM cell population with embryonic signatures and poor immunogenicity. Genome-scale transcriptomic and epigenomic profiling provide a valuable resource for studying immune evasion mechanisms governing c-GSCs and identifying potential therapeutic targets for GBM immunotherapy.

The role of vitamin D in breast cancer risk and progression

The active form of vitamin D3, 1,25-dihydroxvitamin D3 [1,25(OH)2D3], is primarily known as a key regulator of calcium and phosphate homeostasis. It exerts its biological functions by binding to the vitamin D receptor (VDR), a transcription factor that regulates gene expression in vitamin D-target tissues such as intestine, kidney and bone. Yet, the VDR is expressed in many additional normal and cancerous tissues, where it moderates the antiproliferative, prodifferentiating and immune-modulating effects of 1,25(OH)2D3. Interestingly, several epidemiological studies show that low levels of 25(OH)D3, a biological marker for 1,25(OH)2D3 status, are associated with increased risk of breast cancer (BC) development. Mendelian randomization studies, however, did not find any relationship between single-nucleotide polymorphisms in genes associated with lower serum 25(OH)D3 and BC risk. Nevertheless, multiple in vitro and in vivo preclinical studies illustrate that 1,25(OH)2D3 or its less calcaemic structural analogues influence diverse cellular processes in BC such as proliferation, differentiation, apoptosis, autophagy and the epithelial-mesenchymal transition. Recent insights also demonstrate that 1,25(OH)2D3 treatment impacts on cell metabolism and on the cancer stem cell population. The presence of VDR in the majority of BCs, together with the various antitumoural effects of 1,25(OH)2D3, have supported the evaluation of the effects of vitamin D3 supplementation on BC development. However, most randomized controlled clinical trials do not demonstrate a clear decrease of BC incidence with vitamin D3 supplementation. However, 1,25(OH)2D3 or its analogues seem biologically more active, and may have more potential anticancer activity in BC upon combination with existing cancer therapies.

​The Analysis of Reproduction-related Genes Provides Insights into the Adaptive Evolution of Fecundity Traits in Yangtze Finless Porpoise

Background: Yangtze finless porpoise (YFP, Neophocaena asiaeorientalis), is the first class protected animal in China. In order to analyze the adaptive evolution of fecundity traits in YFP, the rapidly evolving gene families of YFP were obtained. At the same time, the major genes controlling ovulation, GDF9, BMP15, FSHβ and FSHR were also analyzed. Methods: Orthofinder software was employed to search homologous genes based on protein sequence. CAFÉ software was used to obtain the expansion and contraction gene families of YFP. Then, GO terms and pathway enrichment analyses were performed using TBtools software and Swissprot database. PAML package was used to calculate Ka/Ks (i.e., ω). Evolution rate changes in the positive selected genes were examined using the GU99 process in Diverge (v3.0) program. Result: In YFP, 501 rapid expansion gene families GO enrichment results showed that the reproductive activities related pathways were mainly three significant enrichment process, participation of germline stem cells maintain androgen receptors signaling pathways regulating and male reproductive tract stem cell population to maintain. The most significant GO terms of 220 rapidly contraction gene families associated with reproductive activities mainly consisted of biological processes which were involved in positive regulation of estrogen secretion, mating and estrogen metabolic process. GDF9 and BMP15 genes exhibited purifying selection. However, significant signs of positive selection were detected in FSHR and FSHβ genes, but only FSHβ showed specific changes in the YFP lineage.

The dynamics of HD-ZIP III - ZPR protein interactions play essential roles in embryogenesis, meristem function and organ development

Maintaining a stem cell population while developing lateral organs is a crucial aspect of plant development. Studies have shown that a family of micro proteins, the LITTLE ZIPPERS (ZPR), are involved in this process by repressing the activity of HD-ZIP III transcription factors. However, the unique role of each ZPR has not been thoroughly characterized. In this work, we use genetics, imaging, and biochemistry to create a detailed picture of ZPR family expression and their specific interactions with HD-ZIP IIIs. CRISPR/Cas9 was implemented to isolate single loss-of-function ZPR alleles as well as higher-order mutant combinations. A single mutation in ZPR1, ZPR3, and ZPR4 affects the development of the cotyledons during embryogenesis. Additionally, double mutant analyses indicates both unique roles for each ZPR protein as well as redundancy. Using ZPR tagged lines we show that while ZPR3 and ZPR4 have a similar pattern of accumulation as the HD-ZIP IIIs, ZPR1 and ZPR2 accumulation is more limited. Immuno-precipitations (IP) with tagged ZPR proteins are mainly enriched with the anticipated HD-ZIP III partners. Although ZPRs interact with all HD-ZIP IIIs, an apparent preference of heterodimer formation with REVOLUTA is observed. Our work highlights that the dynamics of ZPR protein accumulation together with the strength of ZPR-HD-ZIP III interactions provide an added layer of complexity to the regulation of HD-ZIP IIIs during plant development.