A PUZZLING HEPATIC TUMOR: EPITHELIOID ANGIOMYOLIPOMA WITH A MINOR ADIPOCYTIC COMPONENT

Hepatic epithelioid angiomyolipomas are uncommon mesenchymal neoplasms. They are difficult to diagnose by imaging, especially when the fatty component is scant or absent. The gold standard for the diagnosis is histologic examination coupled with an immunohistochemical study. Positive HMB-45 immunostaining of the myoid cells is a major diagnostic feature.

Study on the Mechanism of Mirna-21 Affecting the Differentiation of Bone Marrow Mesenchymal Stem Cells into Cardiomyocyte-Like Cells By Targeting Ajuba / Isl1 Axis

Purpose: To study the mechanism of miRNA-21 targeting ajuba/ Isl1 axis to affect BMSC differentiation to cardiac myoid cells. Methods: BMSC was cultured and miRNA-21 was constructed to infect BMSC. The miRNA-21 was directly regulated by luciferase reporter gene system. The expression of cTnI, ajuba and Isl1 was detected by RT-qPCR and WB. The expression of cTnI, ajuba and Isl1 was detected by RT-qPCR and WB, and miR-21 was detected by RT-qPCR; The differentiation ability of BMSC in all groups was detected by RT-qPCR and WB; To evaluate the effect of ajuba and Isl1 on the differentiation ability of BMSC. Results: BMSC was cultured successfully, BMSC was successfully constructed by mir-21-OE, mir-21-KD, ajuba-OE and ajuba KD slow virus; RT-qPCR and WB were used to detect the high expression of cTnI in mir-21-OE and ajuba KD groups, and the expression of miR-21 was increased, the expression of ajuba was inhibited and Isl1 expression was enhanced. Conclusion: The expression of ajuba was inhibited by up regulation of miRNA-21 target, and the expression of Isl1 enhanced to promote BMSC differentiation, that is, miRNA-21 regulated the axis of ajuba/ Isl1 to influence the differentiation of BMSC to cardiomyocyte-like cells.

TCF21+ mesenchymal cells contribute to testis somatic cell development, homeostasis, and regeneration in mice

Testicular development and function rely on interactions between somatic cells and the germline, but similar to other organs, regenerative capacity declines in aging and disease. Whether the adult testis maintains a reserve progenitor population remains uncertain. Here, we characterize a recently identified mouse testis interstitial population expressing the transcription factor Tcf21. We found that TCF21lin cells are bipotential somatic progenitors present in fetal testis and ovary, maintain adult testis homeostasis during aging, and act as potential reserve somatic progenitors following injury. In vitro, TCF21lin cells are multipotent mesenchymal progenitors which form multiple somatic lineages including Leydig and myoid cells. Additionally, TCF21+ cells resemble resident fibroblast populations reported in other organs having roles in tissue homeostasis, fibrosis, and regeneration. Our findings reveal that the testis, like other organs, maintains multipotent mesenchymal progenitors that can be potentially leveraged in development of future therapies for hypoandrogenism and/or infertility.

Leptin Secreted in the Testicular Microenvironment Promotes the Endogenous Function of Leydig Cells Through Hedgehog Signaling Pathway

Objective: Testosterone deficiency (TD) is a common health concern, affecting around 1 in 5 men globally. However, the factors responsible for TD remain largely unknown. Leydig cells produce testosterone in the testes under the pulsatile control of luteinizing hormone (LH) from the pituitary gland. Leydig stem cells (LSC) have the potential to differentiate into adult Leydig cells, which can increase testosterone levels; however, the factors promoting differentiation are unknown. In the present study we evaluated the paracrine factors released from the testicular microenvironment (TME) (comprised of Sertoli and peritubular myoid cells) that modulate the differentiation of Leydig stem cells to adult Leydig cells. Additionally, we explored the underlying mechanism of action of these paracrine factors. Methods: Tissue samples were obtained from a total of 13 men with testicular failure, who underwent testis biopsies for sperm retrieval. Using an IRB approved protocol, about 10mg of testicular tissue from each sample were processed for LSC isolation, culturing, and characterization. Cytokine antibody array was performed to identify the paracrine factors released by Sertoli and peritubular myoid cells using unsorted and CD146+ve sorted cells. The cells were treated with hedgehog signaling agonist and antagonist to validate the specificity of paracrine factors identified. Immunostaining was performed to evaluate changes at the protein level. Flow cytometry was performed to study the shift in the population of cells post leptin treatment. GraphPad Prism (GraphPad Software) was used for statistical analysis. Results: This study revealed that the TME plays an instrumental role in Leydig stem cell differentiation and testosterone production through regulation of the desert hedgehog (DHH) signaling pathway. TME-secreted leptin induces LSC differentiation and increases testosterone production. However, these effects are inversely concentration-dependent: positive at low leptin doses and negative at higher leptin doses. Mechanistically, leptin acts on LSCs upstream of DHH in a unidirectional fashion, as DHH gain or loss of function was shown to have no effects on Leptin levels. Conclusions: These findings identify leptin as a key paracrine factor released by cells within the TME that modulate LSC differentiation and testosterone production from adult Leydig cells, a finding that is key to developing new niche therapies for TD.

Novel Gene Regulation in Normal and Abnormal Spermatogenesis

Spermatogenesis is a complex and dynamic process which is precisely controlledby genetic and epigenetic factors. With the development of new technologies (e.g., single-cell RNA sequencing), increasingly more regulatory genes related to spermatogenesis have been identified. In this review, we address the roles and mechanisms of novel genes in regulating the normal and abnormal spermatogenesis. Specifically, we discussed the functions and signaling pathways of key new genes in mediating the proliferation, differentiation, and apoptosis of rodent and human spermatogonial stem cells (SSCs), as well as in controlling the meiosis of spermatocytes and other germ cells. Additionally, we summarized the gene regulation in the abnormal testicular microenvironment or the niche by Sertoli cells, peritubular myoid cells, and Leydig cells. Finally, we pointed out the future directions for investigating the molecular mechanisms underlying human spermatogenesis. This review could offer novel insights into genetic regulation in the normal and abnormal spermatogenesis, and it provides new molecular targets for gene therapy of male infertility.

Thymus and autoimmunity

The thymus prevents autoimmune diseases through mechanisms that operate in the cortex and medulla, comprising positive and negative selection and the generation of regulatory T-cells (Tregs). Egress from the thymus through the perivascular space (PVS) to the blood is another possible checkpoint, as shown by some autoimmune/immunodeficiency syndromes. In polygenic autoimmune diseases, subtle thymic dysfunctions may compound genetic, hormonal and environmental cues. Here, we cover (a) tolerance-inducing cell types, whether thymic epithelial or tuft cells, or dendritic, B- or thymic myoid cells; (b) tolerance-inducing mechanisms and their failure in relation to thymic anatomic compartments, and with special emphasis on human monogenic and polygenic autoimmune diseases and the related thymic pathologies, if known; (c) polymorphisms and mutations of tolerance-related genes with an impact on positive selection (e.g. the gene encoding the thymoproteasome-specific subunit, PSMB11), promiscuous gene expression (e.g. AIRE, PRKDC, FEZF2, CHD4), Treg development (e.g. SATB1, FOXP3), T-cell migration (e.g. TAGAP) and egress from the thymus (e.g. MTS1, CORO1A); (d) myasthenia gravis as the prototypic outcome of an inflamed or disordered neoplastic ‘sick thymus’.

Unusual Myoid Differentiation in a Canine Benign Mixed Mammary Tumour

This report describes an unusual mesenchymal differentiation in a canine benign mixed mammary tumour. A 13-year-old crossbreed female dog was submitted to surgery to remove an inguinal mammary nodule. The tumour was composed of mammary epithelium and mesenchymal populations, not only of cartilage and bone but also of myoid cells. PTAH demonstrated cross striation of striated muscle, and immunohistochemistry highlighted striated muscle expressing desmin and calponin, and smooth muscle expressing desmin, SMA, and calponin. The tumour was diagnosed as a benign mixed tumour with leio- and rhabdomyoid differentiation. There was no tumour recurrence after one year of clinical follow-up. In conclusion, the well-differentiated features of leiomyocytes and rhabdomyocytes and the growth pattern define the benign origin of the mesenchymal component, which has been confirmed by a benign outcome; therefore, the knowledge of this kind of differentiation is helpful to avoid misdiagnoses.

Expression of Wnt5a defines the major progenitors of fetal and adult Leydig cells

SummaryLeydig cells (LCs) are the major androgen-producing cells in the testes. They arise from steroidogenic progenitors, whose origins, maintenance and differentiation dynamics remain largely unknown. Here, we identified Wnt5a as a specific marker of steroidogenic progenitors, whose expression begins at around E11.5-E12.5 in interstitial cells of the fetal mouse testis. In vivo lineage tracing indicates that Wnt5a-expressing progenitors are initially present in large numbers in the fetal testis and then progressively decrease as development progresses. We provide evidence that Wnt5a-expressing cells are bona fide progenitors of peritubular myoid cells as well as fetal and adult LCs, contributing to most of the LCs present in the fetal and adult testis. Additionally, we show in the adult testis that Wnt5a expression is restricted to a subset of LCs exhibiting a slow but noticeable clonal expansion, revealing hitherto unappreciated proliferation of fully differentiated LCs as a contribution to the adult LC pool.

Immunolocalization of aromatase P450 in the epididymis of Podarcis sicula and Rattus rattus

The goal of this study was to evaluate P450 aromatase localization in the epididymis of two different vertebrates: the lizard Podarcis sicula, a seasonal breeder, and Rattus rattus, a continuous breeder. P450 aromatase is a key enzyme involved in the local control of spermatogenesis and steroidogenesis and we proved for the first time that this enzyme is represented in the epididymis of both P. sicula and R. rattus. In details, P450 aromatase was well represented in epithelial and myoid cells and in the connective tissue of P. sicula epididymis during the reproductive period; instead, during autumnal resumption this enzyme was absent in the connective tissue. During the non-reproductive period, P450 aromatase was localized only in myoid cells of P. sicula epididymis, whereas in R. rattus it was localized both in myoid cells and connective tissue. Our findings, the first on the epididymis aromatase localization in the vertebrates, suggest a possible role of P450 aromatase in the control of male genital tract function, particularly in sperm maturation.