Early embryonic exposure to chlorpyrifos-cypermethrin combination induces pattern deficits in the heart of domestic hen.

Exposure to chlorpyrifos-cypermethrin combination during early development resulted in defective looping and ventricular noncompaction of heart in domestic chicken. The study was extended to elucidate the molecular basis of this novel observation. The primary culture of chicken embryonic heart cells showed a concentration-dependent loss of viability when challenged with this combination of technical-grade insecticides. Comet assay, DNA ladder assay, and analyses of appropriate markers at transcript and protein levels, revealed that chlorpyrifos-cypermethrin combination induced cell death by activating apoptosis. Parallelly, the tissues derived from control and experimental group hearts were checked for apoptotic markers, and the result was much similar to that of the in-vitro study. Further analysis showed that chlorpyrifos-cypermethrin combination deranged the expression pattern of the transcriptional regulators of cardiogenesis, namely TBX20, GATA5, HAND2, and MYOCD. This, together with heightened apoptosis, could well be the reason behind the observed structural anomalies in the heart of chlorpyrifos-cypermethrin poisoned embryos.

Evaluation of multikinase inhibitor LDN193189 induced hepatotoxicity in teleost fish Poecilia latipinna.

Currently, scientists show keen interest in the drugs that inhibit multiple kinases, LDN193189, being an example. It combats certain cancers in vitro as well as in vivo, making it a prerequisite for researchers to study the toxic potential of this drug in animal models. As most of the drugs metabolized by liver cause hepatic injury, LDN193189-induced hepatotoxicity was examined using a teleost fish, Poecilia latipinna. As a prelude, calculation of LD50 showed a value of 95.22 mg/kg body weight and three doses were decided based on it for further evaluations. All these groups were tested for antioxidant enzyme levels and were significantly raised for mid- and high-dose group. Similar trend was recorded for ALP, AST, and ALT levels. Furthermore, some key indicators of drug metabolism in liver were tested for their expression in response to LDN193189 treatment. Among these, Cyt-C, CYP3A4, CYP1B1 and CYP1A1 were elevated in mid- and high dose, except CYP21A1, which declined remarkably. Moreover, histological profile of the liver reflected high degree of inflammation due to drug treatment, but this was found only at high dose. In summary, LDN193189, at 2.5 mg/kg body weight, did not cause any adverse hepatotoxicity, rendering it safe for use as an anti-proliferative agent - an activity for which it has already shown promising results in the same animal model. The low-dose group previously studied for its anti-proliferative property showed no adverse effect in liver, whereas the mid- and high dose induced moderate or severe hepatotoxicity in P. latipinna.

Cyclooxygenase-2 interacts with MMP and FGF pathways to promote epimorphic regeneration in lizard Hemidactylus flaviviridis.

Cyclooxygenase-2 (COX-2) is an inducible enzyme known for its role in promoting inflammation, pain and cancer. It has more recently been attributed a function in epimorphic regeneration of vertebrate appendages. However, its position among the molecular regulators of regeneration remains unclear. This work was aimed at analyzing the influence of COX-2 on critical mediators of regenerative processes in the lizard Hemidactylus flaviviridis. It was found during the early events of regeneration that MMP and FGF genes get altered in their expression in response to administration of etoricoxib, a COX-2 inhibitor. Results herein also reflect a positive correlation between COX-2 activity and gelatinase activities in our system. These observations, for the first time, establish a definitive interaction of the COX-2 signal with the MMPs and FGFs as essential to the initiation of tail regeneration, placing it as one of the top regulators of the molecular events which characterize epimorphosis.

Inherent variations in the cellular events at the site of amputation orchestrate scar-free wound healing in the tail and scarred wound healing in the limb of lizard Hemidactylus flaviviridis.

Lizards are unique in having both-regeneration competent (tail) as well as non-regenerating appendages (limbs) in adults. They therefore present an appropriate model for comparing processes underlying regenerative repair and nonregenerative healing after amputation. In the current study, we use northern house gecko Hemidactylus flaviviridis to compare major cellular and molecular events following amputation of the limb and of the tail. Although the early response to injury in both cases comprises apoptosis, proliferation, and angiogenesis, the temporal distribution of these processes in each remained obscure. In this regard, observations were made on the anatomy and gene expression levels of key regulators of these processes during the healing phase of the tail and limb separately. It was revealed that cell proliferation markers like fibroblast growth factors were upregulated early in the healing tail, coinciding with the growing epithelium. The amputated limb, in contrast, showed weak expression of proliferation markers, limited only to fibroblasts in the later stage of healing. Additionally, apoptotic activity in the tail was limited to the very early phase of healing, as opposed to that in the limb, wherein high expression of caspase-3 was observed throughout the healing process. Early rise in VEGF-α expression reflected an early onset of angiogenesis in the tail, while it was seen to occur at a later stage in case of the limb. Moreover, the expression pattern of transforming growth factor beta members points toward a pro-fibrotic response being induced very early in the amputated limb. Collectively, these results explain why regenerating appendages are able to heal without scars and if we are to induce scar-free healing in nonregenerating limbs, what interventions can be envisaged. This is crucial to the field of regenerative medicine since it is the initial stages of repair following amputation, which decide whether the appendage will be restored or only covered with a scab.

COX-2 activity and expression pattern during regenerative wound healing of tail in lizard Hemidactylus flaviviridis.

Cyclooxygenase-2 (COX-2) is an important mediator of the immune response. It is found upregulated after pathogen invasion or tissue injury and also in many cancers. Of the lesser known functions of this enzyme is its role in effecting epimorphic regeneration. We have previously shown that COX-2 activity is essential for proper regeneration of tail in lizard Hemidactylus flaviviridis; however, the pattern of its activity and expression during the early stages of regeneration was unknown. The present work provides the first report of the trend in COX-2 activity and expression during the wound healing in epimorphic regeneration. It was found in H. flaviviridis that COX-2 gene was induced on the first day after amputation of the tail and expression and activity remained high through the course of wound healing. Further it was revealed that the COX-2 signal was mediated through the PKA/cAMP pathway via binding with the prostaglandin E2 receptor 2 (EP2). In order to delineate the mechanism of epimorphic regeneration, we must understand the regulation of the major regulatory molecules therein. Therefore, the current study on the role of COX-2 during the regenerative wound healing is of paramount significance. Optimistically, such a mechanistic insight will help us achieve large scale tissue regeneration in humans in the future.

BMP signaling regulates the skeletal and connective tissue differentiation during caudal fin regeneration in sailfin molly (Poecilia latipinna).

Caudal fin regeneration in sailfin molly, Poecilia latipinna (Lesueur 1821) involves an initial wound healing stage, followed by blastema that is formed of fast proliferating cells. In order to replicate the lost fin, correct differentiation of the blastemal cells into various tissues is the prime essence. Among the molecular signals governing proper differentiation of blastemal cells, members of the bone morphogenetic protein (BMP) family are crucial. Herein, we investigated the specific effects of inhibition of BMP signaling using LDN193189 on skeletal and connective tissue formation in the regenerating tail fin of P. latipinna during early differentiation phase. It was observed that BMP inhibition leads to reduction in the length of regeneration, which can be correlated with compromised proliferation of blastemal cells. Decreased expression of cell proliferation marker like pcna together with reduced BrdU positive cells consolidate the above observation. Further, histological analysis revealed stunted progression of skeletal tissues and this correlated with the reduced expression of sox9, runx2 and dlx5, Osc and Osn genes in response to BMP inhibition. Also, defective bone patterning was observed due to BMP inhibition, which was associated with diminished levels of shh, ptc-1, gli2 and other BMP ligands. Moreover, histochemical analysis revealed that collagen, one of the most prominent components of connective tissue, was formed below par in treated fin tissues which was subsequently confirmed by biochemical and transcript level analyses. Overall our results highlight the importance of the BMP pathway in proper differentiation of skeletal and connective tissues during the differentiation stage of regenerating caudal fin.

Barriers and facilitators to use of buprenorphine in state-licensed specialty substance use treatment programs: A survey of program leadership.

INTRODUCTION: Medications for opioid use disorder (MOUD), including buprenorphine, reduce overdose risk and improve outcomes for individuals with opioid use disorder (OUD). However, historically, most non-opioid treatment program (non-OTP) specialty substance use treatment programs have not offered buprenorphine. Understanding barriers to offering buprenorphine in specialty substance use treatment settings is critical for expanding access to buprenorphine. This study aims to examine program-level attitudinal, financial, and regulatory factors that influence clients' access to buprenorphine in state-licensed non-OTP specialty substance use treatment programs. METHODS: We surveyed leadership from state-licensed non-OTP specialty substance use treatment programs in New Jersey about organizational characteristics, including medications provided on- and off-site and percentage of OUD clients receiving any type of MOUD, and perceived attitudinal, financial, and regulatory barriers and facilitators to buprenorphine. The study estimated prevalence of barriers and compared high MOUD reach (n = 36, 35 %) and low MOUD reach (n = 66, 65 %) programs. RESULTS: Most responding organizations offered at least one type of MOUD either on- or off-site (n = 80, 78 %). However, 71 % of organizations stated that fewer than a quarter of their clients with OUD use any type of MOUD. Endorsement of attitudinal, financial, and institutional barriers to buprenorphine were similar among high and low MOUD reach programs. The most frequently endorsed government actions suggested to increase use of buprenorphine were facilitating access to long-acting buprenorphine (n = 95, 96 %), education and stigma reduction for clients and families (n = 95, 95 %), and financial assistance to clients to pay for medications (n = 90, 90 %). CONCLUSIONS: Although non-OTP specialty substance use programs often offer clients access to MOUD, including buprenorphine, most OUD clients do not actually receive MOUD. Buprenorphine uptake in these settings may require increased financial support for programs and clients, more robust education and training for providers, and efforts to reduce the stigma associated with medication among clients and their families.

Exploring trauma and wellbeing of people who use drugs after witnessing overdose: A qualitative study.

BACKGROUND: The national overdose crisis is often quantified by overdose deaths, but understanding the traumatic impact for those who witness and respond to overdoses can help elucidate mental health needs and opportunities for intervention for this population. Many who respond to overdoses are people who use drugs. This study adds to the literature on how people who use drugs qualitatively experience trauma resulting from witnessing and responding to overdose, through the lens of the Trauma-Informed Theory of Individual Health Behavior. METHODS: We conducted 60-min semi-structured, in-depth phone interviews. Participants were recruited from six states and Washington, DC in March-April 2022. Participants included 17 individuals who witnessed overdose(s) during the COVID-19 pandemic. The interview guide was shaped by theories of trauma. The codebook was developed using a priori codes from the interview guide; inductive codes were added during content analysis. Transcripts were coded using ATLAS.ti. RESULTS: A vast majority reported trauma from witnessing overdoses. Participants reported that the severity of trauma varied by contextual factors such as the closeness of the relationship to the person overdosing or whether the event was their first experience witnessing an overdose. Participants often described symptoms of trauma including rumination, guilt, and hypervigilance. Some reported normalization of witnessing overdoses due to how common overdoses were, while some acknowledged overdoses will never be "normal." The impacts of witnessing overdose on drug use behaviors varied from riskier substance use to increased motivation for treatment and safer drug use practices. CONCLUSION: Recognizing the traumatic impact of witnessed overdoses is key to effectively addressing the full range of sequelae of the overdose crisis. Trauma-informed approaches should be central for service providers when they approach this subject with clients, with awareness of how normalization can reduce help-seeking behaviors and the need for psychological aftercare. We found increased motivation for behavior change after witnessing, which presents opportunity for intervention.

Identifying the core genome of the nucleus-forming bacteriophage family and characterization of Erwinia phage RAY.

We recently discovered that some bacteriophages establish a nucleus-like replication compartment (phage nucleus), but the core genes that define nucleus-based phage replication and their phylogenetic distribution were unknown. By studying phages that encode the major phage nucleus protein chimallin, including previously sequenced yet uncharacterized phages, we discovered that chimallin-encoding phages share a set of 72 highly conserved genes encoded within seven distinct gene blocks. Of these, 21 core genes are unique to this group, and all but one of these unique genes encode proteins of unknown function. We propose that phages with this core genome comprise a novel viral family we term Chimalliviridae. Fluorescence microscopy and cryo-electron tomography studies of Erwinia phage vB_EamM_RAY confirm that many of the key steps of nucleus-based replication encoded in the core genome are conserved among diverse chimalliviruses, and reveal that non-core components can confer intriguing variations on this replication mechanism. For instance, unlike previously studied nucleus-forming phages, RAY doesn't degrade the host genome, and its PhuZ homolog appears to form a five-stranded filament with a lumen. This work expands our understanding of phage nucleus and PhuZ spindle diversity and function, providing a roadmap for identifying key mechanisms underlying nucleus-based phage replication.

Identifying the core genome of the nucleus-forming bacteriophage family and characterization of Erwinia phage RAY.

We recently discovered that some bacteriophages establish a nucleus-like replication compartment (phage nucleus), but the core genes that define nucleus-based phage replication and their phylogenetic distribution were still to be determined. Here, we show that phages encoding the major phage nucleus protein chimallin share 72 conserved genes encoded within seven gene blocks. Of these, 21 core genes are unique to nucleus-forming phage, and all but one of these genes encode proteins of unknown function. We propose that these phages comprise a novel viral family we term Chimalliviridae. Fluorescence microscopy and cryoelectron tomography studies of Erwinia phage vB_EamM_RAY confirm that many of the key steps of nucleus-based replication are conserved among diverse chimalliviruses and reveal variations on this replication mechanism. This work expands our understanding of phage nucleus and PhuZ spindle diversity and function, providing a roadmap for identifying key mechanisms underlying nucleus-based phage replication.

Management of Patients With Advanced Urothelial Carcinoma in an Evolving Treatment Landscape: A Qualitative Study of Provider Perspectives of First-Line Therapies.

INTRODUCTION: The treatment landscape in locally advanced/unresectable or metastatic urothelial carcinoma (aUC) has evolved with the use of immune checkpoint inhibitors (ICIs) in the first line (1L) and platinum-refractory settings and with the recent approval of avelumab as 1L maintenance therapy for patients achieving disease control with platinum-containing regimens. Oncology provider perspectives and decision-making processes regarding aUC management, especially with the integration of recently approved strategies, such as maintenance therapy, have not been well-described. PATIENTS AND METHODS: Qualitative interview study with US oncologists and oncology nurses in academic and community settings in August 2020. Interviews explored decision-making around aUC 1L treatment eligibility determinants and selection, programmed cell death 1 ligand 1 (PD-L1) testing practices, and use of maintenance therapy. Thematic analysis was used to identify drivers of 1L treatment decisions. RESULTS: Eighteen oncologists (women, 11%; >15 years in practice, 55%; academic, 39%) and 18 oncology nurses (women, 94%; >15 years in practice, 34%; academic, 50%) participated. Providers preferred platinum-based regimens in 1L setting and reserved 1L ICI monotherapy for frail patients. Providers preferred chemotherapy followed by switch maintenance ICI, as opposed to concurrent combination chemotherapy and ICI, followed by ICI as continuation maintenance. Decision-making was driven by need to adhere to treatment decision-making guidelines, characteristics of the patient, treatment efficacy and patient preference. CONCLUSION: Providers adhered to guidelines and level I evidence in decision-making in the aUC 1L setting. Future studies should further evaluate barriers to the adoption of standard-of-care strategies and factors impacting decision-making in the real-world setting.

Outcome of COVID-19 Infection in Cancer Patients in Pune.

Introduction We document our data on the course of the coronavirus disease 2019 (COVID-19) infection in cancer patients in an attempt to help optimize their management in India and globally. Material and Methods Between February 2020 and January 2021, participating oncologists from Pune (members of the Oncology Group of Pune) documented effect of COVID-19 infection in their cancer patients. Binomial logistic regression analysis as well as correlation analysis was done using Pearson Chi-square test to determine significance of clinical factors. Results A total of 29 oncologists from 20 hospitals contributed their data involving 147 cancer patients who developed COVID-19 infections. COVID-19 infection resulted in higher deaths (likelihood ratio of 4.4) amongst patients with hematological malignancies (12/44 = 27.2%) as compared with those with solid tumors (13/90 = 14.4%, p = 0.030). Patients with uncontrolled or progressive cancer (11/34 = 32.4%) when they got infected with COVID-19 had higher mortality as compared with patients whose cancer was under control (14/113 = 12.4%; p = 0.020). Complication of thromboembolic episodes (seen in eight patients; 5.4% cases) was associated with higher risk (25.6 times) of death (five-eighths; 62.5%) as compared with those who did not develop it (20/139;14.4%; p <0.001). Discussion Patients with cancer should be advised to take strict precautions to reduce the risk of being infected with COVID-19. They should also be given priority for COVID-19 vaccination. If infected with COVID-19, patients with hematological malignancy and uncontrolled cancer are at higher risk of morbidity and mortality. When they are being treated (OPD or inpatient basis), additional precautions are necessary to ensure their exposure to potential COVID-19 virus is minimized. If they get infected with COVID-19, they should be given aggressive treatment to prevent complications, especially thromboembolic episodes. If they develop any thromboembolic complication, their risk of dying are significantly higher, and management should be modified accordingly.

Fibroblast growth factor-2 signaling modulates matrix reorganization and cell cycle turnover rate in the regenerating tail of Hemidactylus flaviviridis.

Lizards restore their lost tail by the recruitment of multipotent cells which are selectively differentiated into varied cell types so as to sculpt a new tail. The precise coordination of the events involved in this complex process requires crosstalk between many signaling molecules and differential regulation of several mediators that facilitate the achievements of various milestones of regeneration. Fibroblast growth factor-2 is one such signaling molecule which activates a number of intracellular signaling pathways. Herein, the regulatory role of FGF2 during tail regeneration in Hemidactylus flaviviridis was investigated. Upon inhibition of FGFR using SU5402, the FGF2 levels were found to be significantly reduced at both transcript and protein level. Further, the compromised levels of the gelatinases, namely MMP2 and MMP9 in the tail tissues of treated lizards indicate that FGF2 regulates the activity of these enzymes perhaps to facilitate the recruitment of multipotent mesenchymal cells (blastema). The in vivo 5BrdU incorporation assay showed a lower cell proliferation rate in FGF2 signal inhibited animals during all the proliferative stages of regeneration studied. This observation was substantiated by decreased levels of PCNA in treated group. Moreover, from the combined results of Caspase-3 localization and its expression levels in the regenerates of control and SU5402 treated lizards it can be deduced that FGF2 signal regulates apoptosis as well during early stages of regeneration. Overall, the current study indicates beyond doubt that FGF2 signaling plays a pivotal role in orchestrating the matrix reorganization and cell cycle turnover during lizard tail regeneration.

Regeneration of caudal fin in Poecilia latipinna: Insights into the progressive tissue morphogenesis.

Studies using fish fin as a model to understand the nuance of epimorphosis are gaining interest of lately. This study illustrates for the first time the daily changes in the tissue architecture of regenerating tail fin of Poecilia latipinna. Wound epithelium is formed within 24 hpa that eventually gets stratified into apical epithelial cap by 48 hpa. In the subsequent day, proliferating cells accumulate in front of each fin-ray marking the beginning of blastema. Distally these cells express signs of cartilage condensation by 4 dpa. However, ossification and subsequent transformation of actinotrichia to lepidotrichia was observed on 5 dpa. Subsequently, the regenerate grew at variable rate until it achieved the original size on 25 dpa. This result would serve as a worthwhile standard reference for further explorative studies that demand manipulation of a regulatory signal at a defined time point.

Ablation of BMP signaling hampers the blastema formation in Poecilia latipinna by dysregulating the extracellular matrix remodeling and cell cycle turnover.

Bone morphogenetic proteins play a pivotal role in the epimorphic regeneration in vertebrates. Blastema formation is central to the epimorphic regeneration and crucially determines its fate. Despite an elaborate understanding of importance of Bone morphogenetic protein signaling in regeneration, its specific role during the blastema formation remains to be addressed. Regulatory role of BMP signaling during blastema formation was investigated using LDN193189, a potent inhibitor of BMP receptors. The study involved morphological observation, in vivo proliferation assay by incorporation of BrdU, comet assay, qRT-PCR and western blot. Blastemal outgrowth was seen reduced due to LDN193189 treatment, typified by dimensional differences, reduced number of proliferating cells and decreased levels of PCNA. Additionally, proapoptotic markers were found to be upregulated signifying a skewed cellular turnover. Further, the cell migration was seen obstructed and ECM remodeling was disturbed as well. These findings were marked by differential transcript as well as protein expressions of the key signaling and regulatory components, their altered enzymatic activities and other microscopic as well as molecular characterizations. Our results signify, for the first time, that BMP signaling manifests its effect on blastema formation by controlling the pivotal cellular processes possibly via PI3K/AKT. Our results indicate the pleiotropic role of BMPs specifically during blastema formation in regulating cell migration, cell proliferation and apoptosis, and lead to the generation of a molecular regulatory map of determinative molecules.

A combination insecticide at sub-lethal dose debilitated the expression pattern of crucial signalling molecules that facilitate craniofacial patterning in domestic chick Gallus domesticus.

Pesticides despite being agents that protect the plants and humans from noxious pests, are infamous for their potential to cause detrimental health issues in nontargeted species. In order to ascertain the latter, a set of experiments were conducted by exposing early chick embryos to a widely used combination insecticide (Ci, 50% chlorpyrifos and 5% cypermethrin). The results revealed a myriad of congenital defects pertaining to craniofacial development such as anophthalmia, microphthalmia, exencephaly as well as deformed beak and cranial structures. These teratological manifestations could be attributed to the Ci induced alteration in the titre of major regulators of neurulation and ossification. Therefore, the mRNA and/or the protein level expression pattern of genes which are reported to be involved in the craniofacial development were studied at selected time points of embryonic development. The analysis of the result showed that there have been significant alternations in the expression patterns of the signalling molecules such as SHH, WNTs, CDH1, CDH2, L1CAM, PAX6, HOX, PCNA, GLI3, BMP7, FGF8, GLIs, SOX9, RUNX2, DLX5, COL10A1, CASPASE3 etc. on embryonic days 2, 4 and/or 10. Concurrently, on day 10, whole-mount skeletal staining and biochemical estimation of hydroxyproline were carried out in the cranial tissues of the embryos. The overall result of the current study indicates that exposure to Ci during early development impede the crucial regulatory signals that orchestrate the morphogenesis of cranial neural crest cells thereby hindering the normal progression of neural tube and endochondral ossification which collectively lead to craniofacial dysmorphism in domestic chicks.

Exposure to sub-lethal dose of a combination insecticide during early embryogenesis influences the normal patterning of mesoderm resulting in incomplete closure of ventral body wall of chicks of domestic hen.

Pesticide exposure to the non target groups especially during embryonic development has quite often resulted in congenital malformations. A commercially available combination insecticide (Ci, 50% chlorpyrifos and 5% cypermethrin) is known to induce ventral body wall defects (VBWDs) wherein abdominal viscera protrude out of the ventral body wall. Herein, an attempt was made to understand the mechanistic insight into Ci induced VBWDs. For this, before incubation, the chick embryos were dosed with the test chemical and then at different developmental stages of incubation, they were monitored for the changes in the expression of certain genes, which are indispensable for the ventral body wall closure since they regulate the cell fate, proliferation and survival. Concurrently, histopathological changes during the embryonic development were examined to corroborate the above observations. The results of mRNA profiling revealed a significant downregulation of Shh on day 4 and upregulation on day 10, while bmp4, Pitx2, E-cadherin, Wnt11, Wnt6, Pxn, MyoD1, Caspase-3, AHR, Cyp3A4, showed a significant upregulation on day 4 and/or on day 10. N-cadherin, fgf8, bmp1 showed no significant changes. The possible means by which these skewed expression patterns of regulatory molecules culminated into the VBWD are discussed.

Protein expression pattern and analysis of differentially expressed peptides during various stages of tail regeneration in Hemidactylus flaviviridis.

Epimorphic regeneration is a process allowing the animal to regain its lost structure which depends on the resident pluripotent stem cells as well as de-differentiation of existing cells to form multi-potent stem cells. Many studies have been done to understand the appendage regeneration mechanism. The animal model used since decades is an urodele amphibian the axolotl. However, this ability is also seen in some members of reptiles, mainly lizards which on autotomy of tail regain the same by forming a replica of its lost tail. Lizards being closer to mammals are of greater interest and cannot be neglected. Hence, a stage specific protein profiling was undertaken in order to find the peptides playing a major role in epimorphosis. 2-DGE being basic tool for creating a protein profile was used. With advent of newer modern technology, label-free analysis which uses MS/MS was also performed. The study reports the peptides involved in apoptosis, inflammation and ECM remodelling across the stages of lizard tail regeneration for the first time. Apart from these peptides, structural protein, enzymes involved in metabolism have also been highlighted in the current study to give a bigger picture of the processes and the specific peptides required for tail regeneration.

Inhibition of Cyclooxygenase-2 Alters Wnt/ß-Catenin Signaling in the Regenerating Tail of Lizard Hemidactylus flaviviridis.

Epimorphic regeneration in vertebrates involves the restoration of lost tissue or organs through the formation of a regeneration blastema and occurs through a complex interaction of a number of molecular signaling pathways. Of the many effectors of successful tail regeneration in the lizard Hemidactylus flaviviridis, one crucial pathway is the cyclooxygenase-2 (COX-2) mediated PGE2 signaling pathway. The current study was aimed at understanding whether COX-2 signaling plays any role in the expression of Wnt/ß-Catenin signaling components during regenerative outgrowth in H. flaviviridis. Etoricoxib-selective inhibitor of the inducible isoform of COX-2-was administered to lizards orally. We tested the expression of ß-Catenin during wound epidermis and blastema stages in the regenerating tail and found a reduction in its expression in response to drug treatment. Further, it was observed that the expression of canonical Wnt ligands was greatly altered due to COX-2 inhibition. Our results provide evidence of a cross-talk between the COX-2 induced PGE2 pathway and Wnt/ß-Catenin signaling in the regenerating lizard tail. An understanding of the interaction among various signaling pathways will help elucidate the mechanism underlying epimorphosis in lizards, the only amniotes capable of appendage regeneration.