Pax6 Expression Research Articles

Effects of miR-204-5p modulation on PAX6 regulation and corneal inflammation

Congenital aniridia is a rare eye disease characterized by loss of PAX6 protein leading to aniridia-associated keratopathy that significantly reduces vision. The miR-204-5p is a possible regulator of PAX6 function and here we evaluate its effect in multiple in vitro and in vivo models. In vitro, miR-204-5p overexpression suppressed vascular factor ANGPT1 in human limbal stem cells (T-LSC) and Pax6-knockdown LSC (mut-LSC), and in primary human limbal epithelial cells (LEC) at the gene and protein levels and following LPS stimulation. However, miR-204-5p inhibited VEGFA expression only in mut-LSCs and LPS-stimulated LEC. Also, miR-204-5p increased PAX6 expression in mut-LSC and differentiated corneal epithelial cells, but not in LEC. Topical miR-204-5p after LPS-induced keratitis in mice failed to suppress Vegfa, Angpt1, Il-1β, and Tnf-α or rescue Pax6 levels in contrast to in vitro results, although it significantly reduced the inflammatory infiltrate in the cornea. In Pax6Sey/+ aniridia mice, miR-204-5p did not rescue PAX6 levels or suppress Vegfa, Angpt1, or inhibit the ERK1/2 pathway. While short-term miR-204-5p treatment effectively suppresses VEGFA and ANGPT1 and enhances PAX6 expression in multiple corneal epithelia, effects are variable across primary and immortalized cells. Effects of longer-term in vivo treatment, however, require further study.

SOX17 Expression in Mesotheliomas and Benign Mesothelial Proliferations: Implications for Differential Diagnosis With Gynecologic Carcinomas.

SOX17 has recently emerged as a novel immunohistochemical marker for cancers of endometrial and ovarian origin with improved specificity compared with the widely used Mullerian marker PAX8. However, evaluation of SOX17 in benign and malignant peritoneal mesothelial proliferations remains limited, and these may mimic gynecologic carcinomas, particularly on small biopsies. We evaluated SOX17 and PAX8 expression in 20 benign mesothelial lesions (5 adenomatoid tumors, 5 well-differentiated papillary mesothelial tumors, and 10 peritoneal inclusion cysts) and 16 epithelioid peritoneal mesotheliomas. The 17 female and 3 male patients with benign mesothelial lesions ranged from 20 to 80yr (median: 56.5yr), while the 9 females and 7 males with mesothelioma ranged from 47 to 85yr (median: 57.5yr). SOX17 was positive in 5 (25%) benign lesions (2 adenomatoid tumors, 3 peritoneal inclusion cysts) and 2 (13%) mesotheliomas, while PAX8 stained 8 (40%) benign lesions (1 adenomatoid tumor, 1 well-differentiated papillary mesothelial tumor, 6 peritoneal inclusion cysts), and 2 (13%) mesotheliomas. Results for the 2 stains showed incomplete concordance, with agreement in 15 (75%) benign proliferations and 14 (88%) mesotheliomas. Our findings suggest that SOX17 positivity alone is insufficient to confirm a diagnosis of gynecologic carcinoma over a mesothelial proliferation and pathologists should exercise caution when these entities are diagnostic considerations.

The Effect of Geranylgeraniol and Ginger on Satellite Cells Myogenic State in Type 2 Diabetic Rats

Type 2 diabetes (T2D) is associated with increased inflammation and reactive oxygen species (ROS) in muscles, leading to basal satellite cell (SC) myogenic impairment (i.e., reduction in SC pool), which is critical for maintaining skeletal muscle mass. T2D may contribute to muscle atrophy, possibly due to reductions in the SC pool. Geranylgeraniol (GGOH) and ginger can reduce inflammation and enhance SC myogenesis in damaged muscles, thereby alleviating muscle atrophy; however, their effect on basal SC myogenic state and muscle mass in T2D rats is limited. Rats consumed a control diet (CON), high-fat diet with 35 mg/kg of streptozotocin (HFD), a HFD with 800 mg/kg body weight of GGOH (GG), or a HFD with 0.75% ginger root extract (GRE). In the eighth week, their soleus muscles were analyzed for Pax7, MyoD, and MSTN gene and protein expression, SC myogenic state, and muscle cross-sectional area (CSA). The HFD group had a significantly lower number of Pax7+/MyoD− and Pax7+/MSTN+ cells, less Pax7 and MyoD gene expression, and less MyoD and MSTN protein expression, with a smaller CSA than the CON group. Compared to the GG and GRE groups, the HFD group had a significantly lower number of Pax7+/MSTN+ cells, less MyoD protein expression, and smaller CSA. The GRE group also had a significantly lower number of Pax7−/MyoD+ and greater MSTN protein expression than the HFD group. Nevertheless, the CON group had a significantly greater number of Pax7+/MyoD− than the GG and GRE groups, and a greater number of Pax7−/MyoD+ cells than the GRE group with a larger CSA than the GG group. GGOH and ginger persevered muscle CSA, possibly through increased MyoD and the ability to maintain the SC pool in T2D rats.

Gastric and Gastrointestinal-like Immunophenotypes In Conventional Endometrial Endometrioid Adenocarcinomas Including Endometrioid Adenocarcinomas with Mucinous Differentiation: Frequency and Diagnostic Implications

Abstract Introduction/Objective Mucinous carcinomas of the gastric/gastrointestinal type (MCG) are now recognized as a rare, clinically aggressive subtype of endometrial cancer [EMCa]. However, neither their full morphologic spectrum, nor their defining immunophenotype, has been clearly defined. Previous proposals for their recognition include at least focal immunohistochemical expression of gastrointestinal markers, minimality or absence of ER and possibly PAX8 expression, and the absence of an endometrioid carcinoma component. Herein, we assess the frequency of gastric and gastrointestinal immunophenotypes in conventional endometrioid carcinomas without any discernible gastric/gastrointestinal-type morphology. Methods/Case Report Immunohistochemical analyses for CK7, CK20, CDX2, ER, SATB2, MUC6, PAX8 were performed on 81 EMCa, comprised of consecutively archived cases of low grade endometrioid carcinoma (n=47), FIGO grade III endometrioid carcinoma (n=12), and endometrioid carcinomas with mucinous differentiation (n=22). None showed goblet cells or gastric-type morphology. Expression levels were quantified as H-scores on a standardized 0-300 scale. Results (if a Case Study enter NA) Significant subsets of all 3 groups showed expression of MUC6, CDX2, SATB2 and CK20, without any significant differences between the groups. 56%, 62%, 23% and 25% of cases expressed MUC6, CDX2, CK20 and SATB2 respectively. 37% co-expressed MUC6 and CDX2, 12% co-expressed CDX2 and CK20, 6% co-expressed MUC6, CDX2 and CK20 and 2.5% co-expressed CDX2, CK20 and SATB2. The expression levels were generally low across all groups, with average H scores for positive cases being 49.5 [range 1-250] for MUC6, 33.7 [range 1-285] for CDX2, 24.0 [range 1-270] for CK20, and 30.5 [range; 2-220] for SATB2. There was no statistically significant correlation between the expression of any of the 4 markers (CK20, CDX2, SATB2 or MUC6) and low ER or PAX8 expression. However, the only 2 cases with high CDX2 expression (H: >/=200) were also associated with low ER (H<50) expression, and one of these concurrently showed high CK20 (H: 270) and low PAX8 (H: 2) expression, suggestive of true intestinal differentiation. Conclusion MUC6, SATB2, CDX2, and CK20 are not uncommonly expressed at low levels in endometrioid carcinoma. As such, the expression of these markers cannot be the sole basis for defining the clinically aggressive EMCa with true gastric/gastrointestinal differentiation, and for distinguishing them from conventional endometrioid carcinomas.

Exploring TFE3-Rearranged Renal Cell Carcinoma: A Case Study showing minimal expression of PAX-8

Abstract Introduction/Objective TFE3-rearranged renal cell carcinoma accounts for 1.6-4% of adult renal cell carcinomas (RCC). The histological characteristics of this entity can mimic many other renal cell neoplasms and definite diagnosis is based on immunohistochemical (IHC) and fluorescent in situ hybridization (FISH) analysis. Nonspecific IHC findings can lead to diagnostic challenges delaying confirmatory studies and underdiagnosis. Methods/Case Report A 28-year-old male with sickle cell disease and a right kidney multilocular cystic mass incidentally found during evaluation of splenomegaly underwent partial nephrectomy. The tumor showed papillary, alveolar and sheet-like growth patterns composed of eosinophilic to clear cells with pleomorphic nuclei, including multinucleate forms. Initial ancillary studies showed minimal neoplastic expression (less than 5%) of PAX-8. Repeat PAX-8 yielded similar results and laboratory controls were evaluated successfully. A full work-up showed positivity of AMACR (diffuse), CD10 (diffuse), Cathepsin K (patchy), CK7 (focal), CAIX (focal), and no significant expression of pancytokeratin, HMB-45, Melan-A and SMA. Fumarate hydratase was retained, and the tumor showed a non-specific staining pattern of S (2-succinyl)-cysteine. Controls were appropriate. A high suspicion for a TFE-rearranged RCC was maintained, and a final diagnosis was confirmed with FISH analysis demonstrating a TFE3 (Xp11.23) rearrangement. Results (if a Case Study enter NA) NA Conclusion Reports in the literature detail diffuse PAX-8 expression in TFE3-rearranged RCC. A high index of suspicion based on morphology in our case prompted FISH analysis leading to correct diagnosis. This case highlights the inconsistencies in the reported IHC profile of this entity. More studies are required to elaborate the presentations of this RCC subtype with numerous histologic mimics including the spectrum of immunostaining patterns to better assist patient care for this uncommon variant.

CLIC5 promotes myoblast differentiation and skeletal muscle regeneration via the BGN-mediated canonical Wnt/β-catenin signaling pathway

Myoblast differentiation plays a vital role in skeletal muscle regeneration. However, the protein-coding genes controlling this process remain incompletely understood. Here, we showed that chloride intracellular channel 5 (CLIC5) exerts a critical role in mediating myogenesis and skeletal muscle regeneration. Deletion of CLIC5 in skeletal muscle leads to reduced muscle weight and decreases the number and differentiation potential of satellite cells. In vitro, CLIC5 consistently inhibits myoblast proliferation while promoting myotube formation. CLIC5 promotes myogenic differentiation by activating the canonical Wnt/β-catenin signaling pathway in a biglycan (BGN)–dependent manner. CLIC5 deletion impairs muscle regeneration. Paired box gene 7 (Pax7) expression and the activity of BGN-mediated canonical Wnt/β-catenin signaling are reduced in CLIC5-deficient mice. Conversely, increasing CLIC5 levels in skeletal muscles enhances muscle regeneration capacity. In conclusion, our findings underscore CLIC5 as a pivotal regulator of myogenesis and skeletal muscle regeneration, functioning through interaction with BGN to activate the canonical Wnt/β-catenin signaling pathway.

High-intensity interval training, but not Spirulina supplementation, changes muscle regeneration signaling proteins in aged rats with obesity and diabetes.

This study aimed to investigate changes in protein signaling associated with muscle regeneration in aged rats with obesity and diabetes following high-intensity interval training (HIIT) and SP supplementation. Forty male Wistar rats weighting 280-325 g were used in this study. Obesity was induced by eight weeks of a high-fat diet, and diabetes was induced by intraperitoneal injection of 40 mg/kg streptozocin. Rats were randomly divided into control (CON), sham, SP, HIIT, and HIIT+SP groups. HIIT was performed five times per week during the 8-week period. SP dose was 50 mg/kg. Real-time PCR was used to evaluate the expression of myogenin, MyoD1, and Pax7. The decreases in body mass in the HIIT, HIIT+SP and SP groups were significantly higher than those in the sham and CON groups (p=0.0001). The soleus muscle mass increased significantly only in the HIIT and HIIT+SP groups (p<0.01). HIIT+SP improved fasting blood glucose and insulin levels more than HIIT alone and SP (p<0.05), while HIIT increased the expression levels of myogenic factors more than other groups (p=0.0001). In conclusion HIIT alone had a significant impact on myogenic factors, whereas Spirulina had an effect only when combined with HIIT.

Mechanical Stress-Oxidative Stress Axis: Biological Basis in the Vaginal Wall and Pelvic Floor Muscles of Rats with Simulated Birth Injury.

Vaginal delivery and resulting pelvic floor muscle (PFM) dysfunction are significant risk factors for pelvic floor dysfunction (PFD). Despite this, the biological basis underlying PFD after childbirth remain unclear. This study was aimed at assessing the early response of the vaginal wall and PFM to simulated birth injury (SBI) in rats. Forty female Sprague-Dawley rats were divided into four groups: control (sham operation), and 1, 4, and 14days post-injury. In the SBI groups, a catheter was inserted into the vagina with 130g of weight attached to the end, and the balloon was inflated to 5ml for 2h. Evaluation of vaginal tissues and PFMs included histological, immunohistochemical, Western blot, and uniaxial biomechanical testing. In the vaginal wall, the SBI group showed significantly lower COL1A1 expression and higher MMP-2 and MMP-9 expression. At 4 and 14days post-injury, there was a significant decrease in PFM fiber area and increased collagen content. The SBI group also exhibited significant increases in the expression of Nrf2, NQO1, HO-1, and SOD-2, indicating involvement of oxidative stress in both the vaginal wall and PFMs. Protein expression of Pax7 and MyoG, as well as the number of fibers with centralized nuclei, continued to increase significantly after SBI. Additionally, the vaginal wall of the SBI group showed a decreasing trend in tensile strength and elastic modulus, with a greater ultimate strain. Extracellular matrix remodeling, oxidative stress, decreased biomechanical properties, and muscle dysmyogenesis may collectively contribute to increased susceptibility to PFD development.

8053 A Ligand-Based Differentiation Protocol for Human Induced Pluripotent Stem Cells Recapitulates Granulosa Cell Development and Induces Steroidogenic Pathway Genes

Abstract Disclosure: H. Kubo: None. M.M. Laronda: None. Sex determination is a developmental process that defines the gonad as a testis or ovary, and influences sex hormone production. While key signaling events are well conserved across mammals, there can be differences between species. Therefore, there is a need to develop a human model to fully understand this critical process in humans. We have developed a ligand-based differentiation protocol for human induced pluripotent stem cells (hiPSCs) to generate granulosa-like cells (GLCs). Additionally, hiPSC-derived GLCs could become the foundation for a cell-based hormone replacement therapy that recapitulates cyclicity, physiologic levels of hormones, and production of peptide hormones that are not included in currently available hormone replacement therapies. We aim to gain further understanding of the key factors and culture conditions necessary for functional GLCs that produce ovarian hormones, which includes maintained expression of FOXL2. We used our monolayer differentiation protocol that includes WNT-agonist CHIR99021 treatment for 2 days, followed by a combination treatment of BMP4, FST, and DKK1-inhibitor Gallocyanine for 3 days. We have tested our protocol on three different hiPSC lines: IISH2i-BM9s, STiPS-A3, and STiPS-A6. Expression of pluripotency marker POU5F1 is reduced during differentiation, while expression of the intermediate mesoderm markers PAX2, LHX1, and WT1 and bipotential gonad marker GATA4 peak at day 2. Peak expression of the bipotential gonad marker NR5A1 occurred at day 2 in the STiPS-A6 cells, but at day 5 in IISH2i-BM9 and STiPS-A3 cells. Interestingly, FOXL2 expression peaks at day 2 in all three lines and drops by day 5. In the IISH2i-BM9s, FOXL2 protein peaks at day 2 by Jess Western while there is the highest percentage of FOXL2-positive cells at day 5 by immunofluorescence. In murine granulosa cells, FOXL2 maintenance depends on NR5A2. NR5A2 expression drops in the GLCs, which suggests that NR5A2 loss may be preventing FOXL2 maintenance. Additionally, as FOXL2 is required for expression of aromatase and HSD17B1, we are using this model to interrogate NR5A2 upstream of FOXL2 and control hormone production. CYP19A1 and HSD17B1 along with AMH are induced during this differentiation protocol, suggesting these GLCs can be steroidogenic and produce peptide hormones. Additionally, scRNA-seq analysis of the GLCs is underway to identify types of granulosa cells produced by this protocol. Future directions include optimizing GLC culture conditions to generate hormones and to test if NR5A2 inhibitors alter FOXL2 expression. Put together, the data suggests that cells differentiated with our protocol show promise as a human model of ovarian development and a foundation for a personalized cell-based hormone replacement therapy. This work is supported by the NIH/NICHD R01HD104683 (MML), HuBMAP U01HD110336 (MML), and Gesualdo Family Research Scholar (MML). Presentation: 6/2/2024

Tuina Promotes Repair of Chronic Cervical Muscle Injury by Regulating Satellite Cell Proliferation and Differentiation and Inhibiting Myocyte Apoptosis.

Chronic cervical muscle injury is the first common cause of the development of cervical spondylosis, and Tuina can effectively promote the repair of chronic cervical muscle injury and alleviate neck pain, but the mechanism behind its efficacy is still unknown. The proliferation and differentiation of muscle satellite cells and the apoptosis of cervical myocytes play important roles in the repair of chronic cervical muscle injuries; therefore, this study aimed to explore the potential mechanisms of Tuina to promote the repair of cervical muscle injuries in terms of the proliferation and differentiation of satellite cells and the apoptosis of myocytes. Twenty-eight Wistar rats were randomly divided into control group, model group, Tuina group, and meloxicam group, with 7 rats in each group. Except for the control group, each group were establish a chronic cervical muscle injury model (CCMI). Meloxicam (0.79 mg/kg) was administered by gavage, and in the Tuina group, pressure was applied to the Fengchi acupoint on the affected side once a day. Morphological changes of cervical muscle tissues were detected by ultrasonic diagnostic instrument and HE staining, electrophysiological recordings of electromyographic changes, apoptosis rate was detected by TUNEL staining, and positive expression of Bax, Bcl-2, IGF-1, MyoD, and Pax-7 were detected by Immunohistochemistry and Western blot. In CCMI model rats, we observed that the cervical muscle fibers were disorganized, with irregular morphology, and the amplitude of electromyography was significantly weakened, while Tuina could significantly improve these symptoms and effectively promote the repair of chronic cervical muscle injury. Meanwhile, compared with the model group, Tuina could significantly increase the expression levels of IGF-1 (P<0.01) and MyoD (P<0.05) and decrease the expression level of Pax7 (P<0.05). In addition, we found that the number of apoptotic cells in cervical myocytes was reduced after Tuina intervention (P<0.05), and Tuina inhibited the expression of pro-apoptotic factor Bax (P<0.01) and promoted the expression of anti-apoptotic factor Bcl-2 (P<0.05). Tuina can promote the proliferation and differentiation of satellite cells to repair chronic cervical muscle injury by regulating the expression of Pax7, MyoD, and IGF-1, as well as inhibiting the expression of Bax and promoting the expression of Bcl-2 to ameliorate the apoptosis of cervical myocytes in CCMI model rats.

Expression levels and stoichiometry of Hnf1β, Emx2, Pax8 and Hnf4 influence direct reprogramming of induced renal tubular epithelial cells

Generation of induced renal epithelial cells (iRECs) from fibroblasts offers great opportunities for renal disease modeling and kidney regeneration. However, the low reprogramming efficiency of the current approach to generate iRECs has hindered potential therapeutic application and regenerative approach. This could be in part attributed to heterogeneous and unbalanced expression of reprogramming factors (RFs) Hnf1β (H1), Emx2 (E), Pax8 (P), and Hnf4α (H4) in transduced fibroblasts. Here, we establish an advanced retroviral vector system that expresses H1, E, P, and H4 in high levels and distinct ratios from bicistronic transcripts separated by P2A. Mouse embryonic fibroblasts (MEFs) harboring Cdh16-Cre; mT/mG allele are utilized to conduct iREC reprogramming via directly monitoring single cell fate conversion. Three sets of bicistronic RF combinations including H1E/H4P, H1H4/EP, and H1P/H4E have been generated to induce iREC reprogramming. Each of the RF combinations gives rise to distinct H1, E, P, and H4 expression levels and different reprogramming efficiencies. The desired H1E/H4P combination that results in high expression levels of RFs with balanced stoichiometry. substantially enhances the efficiency and quality of iRECs compared with transduction of separate H1, E, P, and H4 lentiviruses. We find that H1E/H4P-induced iRECs exhibit the superior features of renal tubular epithelial cells, as evidenced by expressing renal tubular-specific genes, possessing endocytotic arrogation activity and assembling into tubules along decellularized kidney scaffolds. This study establishes H1E/H4P cassette as a valuable platform for future iREC studies and regenerative medicine.

Caspase-Activated DNase localizes to cancer causing translocation breakpoints during cell differentiation.

Caspase activated DNase (CAD) induced DNA breaks promote cell differentiation and therapy-induced cancer cell resistance. CAD targeting activity is assumed to be unique to each condition, as differentiation and cancer genesis are divergent cell fates. Here, we made the surprising discovery that a subset of CAD-bound targets in differentiating muscle cells are the same genes involved in the genesis of cancer-causing translocations. In muscle cells, a prominent CAD-bound gene pair is Pax7 and Foxo1a, the mismatched reciprocal loci that give rise to alveolar rhabdomyosarcoma. We show that CAD-targeted breaks in the Pax7 gene are physiologic to reduce Pax7 expression, a prerequisite for muscle cell differentiation. A cohort of these CAD gene targets are also conserved in early differentiating T cells and include genes that spur leukemia/lymphoma translocations. Our results suggest the CAD targeting of translocation prone oncogenic genes is non-pathologic biology and aligns with initiation of cell fate transitions.

Cycloleucine induces neural tube defects by reducing Pax3 expression and impairing the balance of proliferation and apoptosis in early neurulation

S-adenosylmethionine (SAM) plays a critical role in the development of neural tube defects (NTDs). Studies have shown that the paired box 3 (Pax3) gene is involved in neural tube closure. However, the exact mechanism between Pax3 and NTDs induced by SAM deficiency remains unclear. Here, The NTD mouse model was induced using cycloleucine (CL), an inhibitor of SAM biosynthesis, to determine the effect of Pax3 on NTDs. The effect of CL on NTD occurrence was assessed by 5-ethynyl-2′-deoxyuridine (EdU) staining, immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), and Western blot in NTD embryonic brain tissues and immortalized hippocampal neuron cells (HT-22). A high incidence of NTDs was observed when CL was administered at a dose of 200 mg/kg body weight. The levels of SAM and Pax3 were significantly reduced in NTD embryonic brain tissues and HT-22 cells after CL exposure. Decreased proliferation and excessive apoptosis were observed in neuroepithelial cells of NTD embryos and HT-22 cells under SAM deficiency, but these effects were reversed by overexpression of Pax3. These results suggest that decreased expression of Pax3 impairs the dynamic balance between cellular proliferation and apoptosis, contributing to NTDs induced by SAM deficiency, which would provide new insights for clarifying the underlying mechanism of NTDs.

Clinicopathologic Analysis of HPV-Related Primary Squamous Cell Carcinoma of the Thyroid.

This study aims to explore the clinical and pathologic characteristics of HPV-related primary thyroid squamous cell carcinoma (PSCCT), a rare tumor classified by WHO-5 as a subtype of anaplastic thyroid carcinoma (ATC). Clinical data, histomorphology, immunohistochemistry, HPV detection, and B-raf gene point mutations of 3 PSCCT cases were analyzed. Subsequent follow-up was conducted post-treatment. All 3 cases involved female patients aged between 60 and 76. Microscopic examination revealed squamous cell carcinoma in cases 1 and 3, whereas case 2 exhibited both squamous cell carcinoma and papillary thyroid carcinoma components. Immunohistochemistry demonstrated CK19, PAX8, and TTF1 expression in the papillary thyroid carcinoma component, and CK5/6, p63, p40, and PAX8 expression in the squamous cell carcinoma component. P16 exhibited diffuse positivity in both squamous cell carcinoma and classic papillary carcinoma. HPV analysis identified low-risk type 6 positivity in cases 1 and 3, while both squamous cell carcinoma and papillary carcinoma areas in case 2 were positive for HPV-33. B-raf gene mutation was exclusive to case 2. Diagnosis of PSCCT necessitates multidisciplinary assessment, incorporating clinical symptoms, imaging, histomorphology, and immunohistochemistry. This study, for the first time, reveals the presence of HPV DNA in both PTC and PSCCT, occurring concurrently but separately. Given the limited scope of 3 case reports, definitive conclusions cannot be drawn, warranting further investigation.

Impact of Extremely Low-Frequency Electromagnetic Fields on Skeletal Muscle of Sedentary Adult Mice: A Pilot Study.

Extremely low-frequency electromagnetic fields (ELF-EMFs) are ubiquitous in industrialized environments due to the continuous use of electrical devices. Our previous studies demonstrated that ELF-EMFs affect muscle cells by modulating oxidative stress and enhancing myogenesis. This pilot study investigated these effects on the skeletal muscles of sedentary adult mice, assessing physiological responses to ELF-EMF exposure and potential modulation by antioxidant supplementation. Male C57BL/6 mice were exposed to ELF-EMFs (0.1 or 1.0 mT) for 1 h/day for up to 5 weeks and fed a standard diet without or with N-acetyl-cysteine (NAC). The results showed transient increases in muscle strength (after 2 weeks of exposure at 1.0 mT), potentially linked to muscle fiber recruitment and activation, revealed by higher PAX7 and myosin heavy chain (MyH) expression levels. After ELF-EMF exposure, oxidative status assessment revealed transient increases in the expression levels of SOD1 and catalase enzymes, in total antioxidant capacity, and in protein carbonyl levels, markers of oxidative damage. These effects were partially reduced by NAC. In conclusion, ELF-EMF exposure affects skeletal muscle physiology and NAC supplementation partially mitigates these effects, highlighting the complex interactions between ELF-EMFs and antioxidant pathways in vivo. Further investigations on ELF-EMFs as a therapeutic modality for muscle health are necessary.

Rack1 regulates B-cell development and function by binding to and stabilizing the transcription factor Pax5.

The transcription factor Pax5 activates genes essential for B-cell development and function. However, the regulation of Pax5 expression remains elusive. The adaptor Rack1 can interact with multiple transcription factors and modulate their activation and/or stability. However, its role in the transcriptional control of B-cell fates is largely unknown. Here, we show that CD19-driven Rack1 deficiency leads to pro-B accumulation and a simultaneous reduction in B cells at later developmental stages. The generation of bone marrow chimeras indicates a cell-intrinsic role of Rack1 in B-cell homeostasis. Moreover, Rack1 augments BCR and TLR signaling in mature B cells. On the basis of the aberrant expression of Pax5-regulated genes, including CD19, upon Rack1 deficiency, further exploration revealed that Rack1 maintains the protein level of Pax5 through direct interaction and consequently prevents Pax5 ubiquitination. Accordingly, Mb1-driven Rack1 deficiency almost completely blocks B-cell development at the pro-B-cell stage. Ectopic expression of Pax5 in Rack1-deficient pro-B cells partially rescues B-cell development. Thus, Rack1 regulates B-cell development and function through, at least partially, binding to and stabilizing Pax5.

New dual inducible cellular model to investigate temporal control of oncogenic cooperating genes

The study of cooperating genes in cancer can lead to mechanistic understanding and identifying potential therapeutic targets. To facilitate these types of studies, we developed a new dual-inducible system utilizing the tetracycline- and cumate-inducible systems driving HES3 and the PAX3::FOXO1 fusion-oncogene, respectively, as cooperating genes from fusion-positive rhabdomyosarcoma. With this model, we can independently induce expression of either HES3 or PAX3::FOXO1, as well as simultaneously induce expression of both genes. This new model will allow us to further investigate the cooperation between HES3 and PAX3::FOXO1 including the temporal requirements for genetic cooperation. Functionally, we show that dual-induction of PAX3::FOXO1 and HES3 modifies sphere formation in a HEK293T-based system. More broadly, this lentiviral dual-inducible system can be adapted for any cooperating genes (overexpression or knockdown), allowing for independent, simultaneous, or temporally controlled gene expression.

Aerobic Exercise Protects against Cardiotoxin-Induced Skeletal Muscle Injury in a DDAH1-Dependent Manner.

Dimethylarginine dimethylaminohydrolase 1 (DDAH1) is a critical enzyme that regulates nitric oxide (NO) signaling through the degradation of asymmetric dimethylarginine (ADMA). Previous studies have revealed a link between the beneficial effects of aerobic exercise and the upregulation of DDAH1 in bones and hearts. We previously reported that skeletal muscle DDAH1 plays a protective role in cardiotoxin (CTX)-induced skeletal muscle injury and regeneration. To determine the effects of aerobic exercise on CTX-induced skeletal muscle injury and the role of DDAH1 in this process, wild-type (WT) mice and skeletal muscle-specific Ddah1-knockout (Ddah1MKO) mice were subjected to swimming training for 8 weeks and then injected with CTX. In WT mice, swimming training for 8 weeks significantly promoted skeletal muscle regeneration and attenuated inflammation, oxidative stress, and apoptosis in the gastrocnemius (GA) muscle after CTX injection. These phenomena were associated with increases in the protein expression of PAX7, myogenin, MEF2A, eNOS, SOD2, and peroxiredoxin 5 and decreases in iNOS expression in GA muscles. Swimming training also decreased serum ADMA levels and increased serum nitrate/nitrite (NOx) levels and skeletal muscle DDAH1 expression. Interestingly, swimming training in Ddah1MKO mice had no obvious effect on CTX-induced skeletal muscle injury or regeneration and did not repress the CTX-induced inflammatory response, superoxide generation, or apoptosis. In summary, our data suggest that DDAH1 is important for the protective effect of aerobic exercise on skeletal muscle injury and regeneration.

Histologic, Phenotypic, and Molecular Characterization of Feline Hodgkin-Like Lymphoma With Classical Reed-Sternberg Cells.

Hodgkin-like lymphoma (HLL) is a rare neoplasm in cats that shares characteristics with the human disease. The hallmark of HLL is the presence of Reed-Sternberg (RS) cells expressing CD30 and CD20. This study aimed to elucidate the clinicopathologic features, immunophenotype and clonality patterns of feline HLL. A comprehensive retrospective review of clinicopathologic and molecular data of nodal lymphomas over a 6-year period was conducted in MyLav laboratory. Twenty-four cases were identified. All cats presented with submandibular or retropharyngeal lymphadenopathy. Histopathologic examination revealed a multifocal to diffuse proliferation of medium-to-large lymphoid cells with low mitotic activity, interspersed RS cells, and a heterogeneous inflammatory infiltrate comprising T-cells, plasma cells and neutrophils. In addition, extensive necrosis was a consistent finding. Immunohistochemistry showed a variable membranous CD20 and nuclear PAX5 expression in neoplastic cells, while RS cells displayed only mild to moderate CD20 positivity and were negative to PAX5. In 21/24 cases (87.5%), RS cells were diffusely CD30-positive. PARR analysis demonstrated clonal B-cell expansion in 60% of cases, with the remaining 40% exhibiting polyclonality. For the 10 cats with available follow-up, the prognosis was generally favourable, with only two cats succumbing to progressive disease. In conclusion, diagnosing feline HLL is challenging. The expression of CD30 and CD20 by RS cells should be considered a hallmark of the disease, but only after excluding differential diagnoses such as anaplastic B-cell lymphoma and granulomatous lymphadenopathy.

Understanding the function of Pax5 in development of docetaxel-resistant neuroendocrine-like prostate cancers

Resistance to the current Androgen Receptor Signaling Inhibitor (ARSI) therapies has led to higher incidences of therapy-induced neuroendocrine-like prostate cancer (t-NEPC). This highly aggressive subtype with predominant small-cell-like characteristics is resistant to taxane chemotherapies and has a dismal overall survival. t-NEPCs are mostly treated with platinum-based drugs with a combination of etoposide or taxane and have less selectivity and high systemic toxicity, which often limit their clinical potential. During t-NEPC transformation, adenocarcinomas lose their luminal features and adopt neuro-basal characteristics. Whether the adaptive neuronal characteristics of t-NEPC are responsible for such taxane resistance remains unknown. Pathway analysis from patient gene-expression databases indicates that t-NEPC upregulates various neuronal pathways associated with enhanced cellular networks. To identify transcription factor(s) (TF) that could be important for promoting the gene expression for neuronal characters in t-NEPC, we performed ATAC-Seq, acetylated-histone ChIP-seq, and RNA-seq in our NE-like cell line models and analyzed the promoters of transcriptionally active and significantly enriched neuroendocrine-like (NE-like) cancer-specific genes. Our results indicate that Pax5 could be an important transcription factor for neuronal gene expression and specific to t-NEPC. Pathway analysis revealed that Pax5 expression is involved in axonal guidance, neurotransmitter regulation, and neuronal adhesion, which are critical for strong cellular communications. Further results suggest that depletion of Pax5 disrupts neurite-mediated cellular communication in NE-like cells and reduces surface growth factor receptor activation, thereby, sensitizing them to docetaxel therapies. Moreover, t-NEPC-specific hydroxymethylation of Pax5 promoter CpG islands favors Pbx1 binding to induce Pax5 expression. Based on our study, we concluded that continuous exposure to ARSI therapies leads to epigenetic modifications and Pax5 activation in t-NEPC, which promotes the expression of genes necessary to adopt taxane-resistant NE-like cancer. Thus, targeting the Pax5 axis can be beneficial for reverting their taxane sensitivity.