The Wnt/β-Catenin Pathway is Activated as a Novel Nucleolar Stress Response

Two Novel Heterozygous Variants in RecA2 Domain of DHX37 Cause 46,XY Gonadal Dysgenesis and Testicular Regression Syndrome

INTRODUCTION

The pathogenic variants in DEAH-box RNA helicase DHX37 are one of the major causes of 46,XY gonadal dysgenesis and testicular regression syndrome (TRS). To date, only 13 different missense variants have been reported. We report two additional cases with different clinical presentations carrying two novel variants in the DHX37 gene.

CASE PRESENTATION AND RESULTS

Case 1 (4.4-year-old boy) presented with significant micropenis and cryptorchidism and was diagnosed as TRS. Case 2 (13.5-year-old girl) had a 46,XY karyotype with female external genitalia and was diagnosed as GD. Two novel DHX37 variants affecting the RecA2 domain, p.G478R and p.L627F, were identified in these cases. Both variants identified in the probands were also present in their unaffected mother.

CONCLUSION

Our findings broaden the variant spectrum of DHX37 in 46,XY differences of sex development (DSD) individuals.

A novel DEAH-box helicase 37 mutation associated with differences of sex development

OBJECTIVE

To determine the genetic etiology of a family pedigree with two patients affected by differences of sex development (DSD).

METHODS

Assess the clinical characteristics of the patients and achieve exome sequencing results and in vitro functional studies.

RESULTS

The 15-year-old proband, raised as female, presented with delayed puberty and short stature associated with atypical genitalia. Hormonal profile showed hypergonadotrophic hypogonadism. Imaging studies revealed the absence of a uterus and ovaries. The karyotype confirmed a 46, XY pattern. Her younger brother presented with a micropenis and hypoplastic scrotum with non-palpable testis and hypospadias. Laparoscopic exploration was performed on the younger brother. Streak gonads were found and removed due to the risk of neoplastic transformation. Post-operative histopathology showed the co-existence of Wolffian and Müllerian derivatives. Whole-exome sequencing identified a novel mutation (c.1223C>T, p. Ser408Leu) in the Asp-Glu-Ala-His-box helicase 37 gene, which was found to be deleterious by in silico analysis. Segregation analysis of the variant displayed a sex-limited, autosomal dominant, maternal inheritance pattern. In vitro experiments revealed that the substitution of 408Ser by Leu caused decreased DHX37 expression both at the mRNA and protein levels. Moreover, the β-catenin protein was upregulated, and the p53 protein was unaltered by mutant DHX37.

CONCLUSIONS

We described a novel mutation (c.1223C>T, p. Ser408Leu) of the DHX37 gene associated with a Chinese pedigree consisting of two 46, XY DSD patients. We speculated that the underlying molecular mechanism might involve upregulation of the β-catenin protein.

MLL-AF4 and a murinized pSer-variant thereof are turning on the nucleolar stress pathway

Background

Recent pathomolecular studies on the MLL-AF4 fusion protein revealed that the murinized version of MLL-AF4, the MLL-Af4 fusion protein, was able to induce leukemia when expressed in murine or human hematopoietic stem/progenitor cells (Lin et al. in Cancer Cell 30:737–749, 2016). In parallel, a group from Japan demonstrated that the pSer domain of the AF4 protein, as well as the pSer domain of the MLL-AF4 fusion is able to bind the Pol I transcription factor complex SL1 (Okuda et al. in Nat Commun 6:8869, 2015). Here, we investigated the human MLL-AF4 and a pSer-murinized version thereof for their functional properties in mammalian cells. Gene expression profiling studies were complemented by intracellular localization studies and functional experiments concerning their biological activities in the nucleolus.

Results

Based on our results, we have to conclude that MLL-AF4 is predominantly localizing inside the nucleolus, thereby interfering with Pol I transcription and ribosome biogenesis. The murinized pSer-variant is localizing more to the nucleus, which may suggest a different biological behavior. Of note, AF4-MLL seems to cooperate at the molecular level with MLL-AF4 to steer target gene transcription, but not with the pSer-murinized version of it.

Conclusion

This study provides new insights and a molecular explanation for the described differences between hMLL-hAF4 (not leukemogenic) and hMLL-mAf4 (leukemogenic). While the human pSer domain is able to efficiently recruit the SL1 transcription factor complex, the murine counterpart seems to be not. This has several consequences for our understanding of t(4;11) leukemia which is the most frequent leukemia in infants, childhood and adults suffering from MLL-r acute leukemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00781-y.

Early and Late Transcriptional Changes in Blood, Neural, and Colon Tissues in Rat Models of Stress-Induced and Comorbid Pain Hypersensitivity Reveal Regulatory Roles in Neurological Disease

Background

Irritable bowel syndrome (IBS) and temporomandibular disorder (TMD) are two chronic pain conditions that frequently overlap in the same individual, more commonly in women. Stress is a significant risk factor, exacerbating or triggering one or both conditions. However, the mechanisms underlying IBS–TMD co-morbidity are mostly unknown.

Aim

To detect both specific and common stress-induced visceral hypersensitivity (SIH) and comorbid TMD–IBS pain hypersensitivity (CPH) genetic signatures over time.

Method

Twenty-four female rats were randomly assigned to one of three experimental groups: naïve, SIH, and CPH (orofacial pain plus stress). RNA was extracted from blood, colon, spinal cord, and dorsal root ganglion 1 or 7 weeks after the stress paradigm. We combined differential gene expression and co-expression network analyses to define both SIH and CPH expression profiles across tissues and time.

Results

The transcriptomic profile in blood and colon showed increased expression of genes enriched in inflammatory and neurological biological processes in CPH compared to SIH rats, both at 1 and 7 weeks after stress. In lumbosacral spinal tissue, both SIH and CPH rats compared to naïve revealed decreased expression of genes related to synaptic activity and increased expression of genes enriched in “angiogenesis,” “Neurotrophin,” and “PI3K-Akt” pathways. Compared to SIH, CPH rats showed increased expression of angiogenesis-related genes 1 week after exposure to stress, while 7 weeks post-stress the expression of these genes was higher in SIH rats. In dorsal root ganglia (DRG), CPH rats showed decreased expression of immune response genes at week 1 and inhibition of nerve myelination genes at 7 weeks compared to naïve. For all tissues, we observed higher expression of genes involved in ATP production in SIH compared to CPH at 1 week and this was reversed 7 weeks after the induction of stress.

Conclusion

Our study highlights an increased inflammatory response in CPH compared to SIH rats in the blood and colon. DRG and spinal transcriptomic profiles of both CPH and SIH rats showed inhibition of synaptic activity along with activation of angiogenesis. Targeting these biological processes may lead to a more profound understanding of the mechanisms underlying IBS–TMD comorbidities and new diagnostic and therapeutic strategies.

Regulation of herpes simplex virus type 1 latency-reactivation cycle and ocular disease by cellular signaling pathways

Following acute infection, herpes simplex virus type 1 (HSV-1) establishes life-long latency in sensory and other neurons. Recurrent ocular HSV-1 outbreaks are generally due to reactivation from latency. The HSV-1 latency-reactivation cycle is a complex virus-host relationship. The viral encoded latency-associated transcript (LAT) is abundantly expressed in latency and encodes several micro-RNAs and other small non-coding RNAs, which may regulate expression of key viral and cellular genes. Certain cellular signaling pathways, including Wnt/β-catenin and mTOR pathway, mediate certain aspect of the latency-reactivation cycle. Stress, via activation of the glucocorticoid receptor and other stress induced cellular transcription factors, are predicted to trigger reactivation from latency by stimulating viral gene expression and impairing immune responses and inflammation. These observations suggest stress and certain cellular signaling pathways play key roles in regulating the latency-reactivation cycle and recurrent ocular disease.

Matrine Exerts Pharmacological Effects Through Multiple Signaling Pathways: A Comprehensive Review

As The main effective monomer of the traditional Chinese medicine Sophora flavescens Ait, matrine has a broad scope of pharmacological activities such as anti-tumor, anti-inflammatory, analgesic, anti-fibrotic, anti-viral, anti-arrhythmia, and improving immune function. These actions explain its therapeutic effects in various types of tumors, cardiopathy, encephalomyelitis, allergic asthma, rheumatoid arthritis (RA), osteoporosis, and central nervous system (CNS) inflammation. Evidence has shown that the mechanism responsible for the pharmacological actions of matrine may be via the activation or inhibition of certain key molecules in several cellular signaling pathways including the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), transforming growth factor-β/mothers against decapentaplegic homolog (TGF-β/Smad), nuclear factor kappa B (NF-κB), Wnt (wingless/ integration 1)/β-catenin, mitogen-activated protein kinases (MAPKs), and Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathways. This review comprehensively summarizes recent studies on the pharmacological mechanisms of matrine to provide a theoretical basis for molecular targeted therapies and further development and utilization of matrine.

The functional role of Pescadillo ribosomal biogenesis factor 1 in cancer

Tumors are neogrowths formed by the growth of normal cells or tissues through complex mechanisms under the influence of many factors. The occurrence and development of tumors are affected by many factors. Pescadillo ribosomal biogenesis factor 1 (PES1) has been identified as a cancer-related gene. The study of these genes may open up new avenues for early diagnosis, treatment and prognosis of tumors. As a nucleolar protein and part of the Pes1/Bop1/WDR12 (PeBoW) complex, PES1 is involved in ribosome biogenesis and DNA replication. Many studies have shown that high expression of PES1 is often closely related to the occurrence, proliferation, invasion, metastasis, prognosis and sensitivity to chemotherapeutics of various human malignant tumors through a series of molecular mechanisms and signaling pathways. The molecules that regulate the expression of PES1 include microRNA (miRNA), circular RNA (circRNA), c-Jun, bromodomain-containing protein 4 (BRD4) and nucleolar phosphoprotein B23. However, the detailed pathogenic mechanisms of PES1 overexpression in human malignancies remains unclear. This article summarizes the role of PES1 in the carcinogenesis, prognosis and treatment of multiple tumors, and introduces the molecular mechanisms and signal transduction pathways related to PES1.

Nucleolar Stress Functions Upstream to Stimulate Expression of Autophagy Regulators

Simple Summary

Ribosome biogenesis takes place in nucleoli and is essential for cellular survival and proliferation. In case this function is disturbed, either due to defects in regulatory factors or the structure of the nucleolus, nucleolar stress is provoked. Consequently, cells classically undergo cell cycle arrest and apoptosis. Induction of nucleolar stress is known to eliminate cells in the background of cancer therapy and paradoxically is also associated with increased cancer formation. Recent reports demonstrated that nucleolar stress triggers autophagy, a conserved pathway responsible for recycling endogenous material. Thus, it was suggested that autophagy might serve as compensatory pro-survival response. However, the mechanisms how nucleolar stress triggers autophagy are poorly understood. Here we show that induction of nucleolar stress by depleting ribosome biogenesis factors or by interfering with RNA polymerase I function, triggers expression of various key autophagy regulators. Moreover, we demonstrate that RNA pol I inhibition by CX-5461 correlates with increased ATG7 and ATGL16L1 levels, essential factors for generating autophagosomes, and stimulates autophagic flux.

Abstract

Ribosome biogenesis is essential for protein synthesis, cell growth and survival. The process takes places in nucleoli and is orchestrated by various proteins, among them RNA polymerases I–III as well as ribosome biogenesis factors. Perturbation of ribosome biogenesis activates the nucleolar stress response, which classically triggers cell cycle arrest and apoptosis. Nucleolar stress is utilized in modern anti-cancer therapies, however, also contributes to the development of various pathologies, including cancer. Growing evidence suggests that nucleolar stress stimulates compensatory cascades, for instance bulk autophagy. However, underlying mechanisms are poorly understood. Here we demonstrate that induction of nucleolar stress activates expression of key autophagic regulators such as ATG7 and ATG16L1, essential for generation of autophagosomes. We show that knockdown of the ribosomopathy factor SBDS, or of key ribosome biogenesis factors (PPAN, NPM, PES1) is associated with enhanced levels of ATG7 in cancer cells. The same holds true when interfering with RNA polymerase I function by either pharmacological inhibition (CX-5461) or depletion of the transcription factor UBF-1. Moreover, we demonstrate that RNA pol I inhibition by CX-5461 stimulates autophagic flux. Together, our data establish that nucleolar stress affects transcriptional regulation of autophagy. Given the contribution of both axes in propagation or cure of cancer, our data uncover a connection that might be targeted in future.

In Leishmania major, the Homolog of the Oncogene PES1 May Play a Critical Role in Parasite Infectivity

Leishmaniasis is a neglected tropical disease caused by Leishmania spp. The improvement of existing treatments and the discovery of new drugs remain ones of the major goals in control and eradication of this disease. From the parasite genome, we have identified the homologue of the human oncogene PES1 in Leishmania major (LmjPES). It has been demonstrated that PES1 is involved in several processes such as ribosome biogenesis, cell proliferation and genetic transcription. Our phylogenetic studies showed that LmjPES encodes a highly conserved protein containing three main domains: PES N-terminus (shared with proteins involved in ribosomal biogenesis), BRCT (found in proteins related to DNA repair processes) and MAEBL-type domain (C-terminus, related to erythrocyte invasion in apicomplexan). This gene showed its highest expression level in metacyclic promastigotes, the infective forms; by fluorescence microscopy assay, we demonstrated the nuclear localization of LmjPES protein. After generating mutant parasites overexpressing LmjPES, we observed that these clones displayed a dramatic increase in the ratio of cell infection within macrophages. Furthermore, BALB/c mice infected with these transgenic parasites exhibited higher footpad inflammation compared to those inoculated with non-overexpressing parasites.

Tumor Endothelial Marker 8 Promotes Proliferation and Metastasis via the Wnt/β-Catenin Signaling Pathway in Lung Adenocarcinoma

Tumor endothelial marker 8 (TEM8), also known as ANTXR1, was highly expressed in cancers, and was identified as a biomarker for early diagnosis and prognosis in some cancers. However, the clinical role and molecular mechanisms of TEM8 in lung adenocarcinoma (LUAD) are still unclear. The present study aimed to explore its clinical value and the molecular mechanisms of TEM8 underlying the progression of LUAD. Our study found the elevation of TEM8 in LUAD cell lines and tissues. What’s more, we observed that the TEM8 expression level was associated with tumor size, primary tumor, and AJCC stage, and LUAD patients with high TEM8 expression usually have a poor prognosis. Then, we conducted a series of experiments by the strategy of loss-of-function and gain-of-function, and our results suggested that the knockdown of TEM8 suppressed proliferation, migration, and invasion and induced apoptosis in LUAD whereas overexpression of TEM8 had the opposite effect. Molecular mechanistic investigation showed that TEM8 exerted its promoting effects mainly through activating the Wnt/β-catenin signaling pathway. In short, our findings suggested that TEM8 played a crucial role in the progression of LUAD by activating the Wnt/β-catenin signaling pathway and could serve as a potential therapeutic target for LUAD.

Ribosomal RNA Transcription Regulation in Breast Cancer

Ribosome biogenesis is a complex process that is responsible for the formation of ribosomes and ultimately global protein synthesis. The first step in this process is the synthesis of the ribosomal RNA in the nucleolus, transcribed by RNA Polymerase I. Historically, abnormal nucleolar structure is indicative of poor cancer prognoses. In recent years, it has been shown that ribosome biogenesis, and rDNA transcription in particular, is dysregulated in cancer cells. Coupled with advancements in screening technology that allowed for the discovery of novel drugs targeting RNA Polymerase I, this transcriptional machinery is an increasingly viable target for cancer therapies. In this review, we discuss ribosome biogenesis in breast cancer and the different cellular pathways involved. Moreover, we discuss current therapeutics that have been found to affect rDNA transcription and more novel drugs that target rDNA transcription machinery as a promising avenue for breast cancer treatment.