Biology subjects

Srikrishna, S.

Publications and source records attributed to Srikrishna, S..

4 recordsLinked to original sources

bioRxiv2024

Scribble knockdown induced metastasis tracking, identification of its associated novel molecular candidates through Proteome and in silico studies

Metastasis is the primary cause of cancer associated death globally. Loss of function of Scribble, a cell polarity regulator/tumor suppressor gene, is associated with many forms of human cancer but its role in cell proliferation and metastasis remains unknown. We generated metastatic cancer in Drosophila using UAS-GAL4 system, through knockdown of Scribble in the wing imaginal discs and tracked metastasis events from 0hr early pupae to 84hrs late pupae using fluorescence microscope. Here, we report, for the first time, that knockdown of Scribble alone could lead to the development of primary tumor in the wing imaginal discs, which is capable of establishing metastasis, leading to secondary tumor formation, eventually resulting in absolute pupal lethality. Further, we checked a metastasis biomarker, MMP1 levels during pre-and post-metastatic phases in Drosophila pupae using qRT-PCR and Western blot analysis. In addition, we analyzed the proteome of Scribble knockdown induced tumor-bearing pupae by 2-D gel electrophoresis followed by MALDI-TOF MS to identify novel proteins involved in the process of tumorigenesis and metastasis. We identified six differentially expressed proteins, Obp 99b, Fer2LCH,CG13492, Hsp23, Ubiquitin and Colt in Scrib knockdown pupae compared to wild-type and validated their expression at the transcriptional level using qRT-PCR. In-silico studies show these novel protein interaction with Scrib. Thus, our results suggested that loss of Scrib alone causes metastasis, without the need for cooperative interaction with oncogenic Ras. The newly identified Fer2LCH (ferritin) and colt proteins could be important candidates for therapeutic target against Scrib associated cell proliferation and metastasis.

cancer biology↗

bioRxiv2024

Drp1-JNK knockdown mitigates Scribble loss induced cell proliferation, metastasis and lethality phenotypes in Drosophila

Mitochondrial dynamics are emerging as master regulators for targeting several types of cancers, including breast cancer, cervical cancer, and hepatocellular carcinoma, for therapeutic intervention. Mitochondrial morphology, size, position and activity within cells is regulated by dynamic fission and fusion events. Dynamin-related protein 1 (Drp1) promotes mitochondrial fission and maintains mitochondrial homeostasis. Loss of Scrib is implicated in several human cancers wherein mitochondrial dysfunction leads to excessive cell proliferation and metastasis. However, the exact molecular mechanisms behind the Scrib loss induced dysregulation of mitochondrial dynamics in cancer progression remains obscure. Although the role of mitochondrial dynamics are being investigated in several types of cancers, but the role of Drp1- mediated fission event in regulating the maintenance of polarity of cells upon loss of Scrib function is elusive. In this study, for the first time, we blocked the function of Drp1 activity in Scrib knockdown induced metastasis cancer model by two ways, firstly, through genetic ablation of Drp1, and secondly by using mdivi-1, a Drp1 specific inhibitor. Genetic depletion of Drp1 expression (Drp1RNAi) in Scrib knockdown cells inhibits Metalloproteinase MMP1, reduces ROS production, restores apico-basal (A/B) cell polarity and enhances ATP production. Further to confirm role of Drp1 in regulation of cell polarity, we employed mdivi, a Drp1 specific inhibitor which has dose dependent effect in cell polarity regulation. This study also reveals that JNK inhibition (JNKRNAi) in Scrib abrogated cells mitigates the Drp1 expression and controls cell proliferation leading to restoration of mitochondrial morphology and epithelial cellpolarity. Our results highlight Drp1 as a key regulator in maintaining the apico-basal polarity of cells which gets affected upon loss of Scrib but Drp1-JNK downregulation effectively mitigates ScribRNAi associated cell proliferation, metastasis and pupal lethality phenotypes.

cancer biology↗

bioRxiv2022

Identification of differentially expressed novel tau associated proteins in transgenic AD model of Drosophila - a proteomic and in silico Approach

Alzheimers disease (AD) is a memory related neurodegenerative disorder mainly associated with older adults. In this study, transgenic Drosophila AD model has been employed to investigate the tau associated proteome. Tau expression was specifically induced in the eye tissues and diseased fly heads were considered for proteomic studies with appropriate controls. We have identified 6 novel proteins from tau induced AD group by 2D and PD Quest analyses and further characterized them by in-vivo and in-silico approaches. The novel Tau interactors, [Obp44a Isoform A, Pglym Isoform A, IP15846p (Adh variant), RE45450p (mRpL2), Retinin, and Glob1 Isoform B], identified by MALDI-TOF/MS were validated through q-RT-PCR. The altered metabolic, behavioral and mitochondrial dynamics associated with Tau over expressing AD flies could be due to the altered expression of Odorant binding protein 44a (Obp44a) and mitochondrial ribosomal protein L2 (mRpL2), respectively. Further, we have showed for the first time the newly identified protein interaction with tau and other regulatory proteins through protein-protein docking, biocomputational classification and evolutionary relationship using in silico studies. Moreover, the study highlights the plausible role of these novel proteins in pathophysiology of phospho-tau induced AD flies and further help unraveling molecular pathways implicated in tauopathies.

neuroscience↗

bioRxiv2019

scribble abrogation induces tumor growth through JNK-Wnt pathways depending on cellular-microenvironment in Drosophila wing imaginal tissue

scribble (scrib) is a cell-polarity determinant in Drosophila and human. Cell polarity plays a crucial role in the maintenance of tissue homeostasis and its disruption leads to neoplastic cancer progression. However, the underlying mechanisms by which loss of cell-polarity regulators drives cancer progression are poorly known. In this study, we have explored the tumor progression mechanisms upon scrib knockdown in Drosophila wing imaginal disc using UASRNAi-GAL4 approach. We have found that scrib knockdown in wing disc leads to tumor growth with disrupted actin cytoskeleton, loss of cell-polarity and elevated JNK signalling, resulting in absolute early pupal lethality. Further, scrib abrogated cells in a large area of the disc are capable of invading the surrounding wild type cells and inducing apoptosis along with compensatory proliferation through JNK-Wnt pathways. Moreover, JNK pathway upstream candidate hep (JNKK) knockdown in scrib abrogated cells rescues the cell polarity defects, actin cytoskeleton disruption and tumor growth, while constitutive hep activation further aggravates the tumor phenotype. Interestingly, generation of undead cells by apoptosis inhibition in these hep knockdown cells by p35 expression further leads to tumor development. Hence, we conclude that scrib knockdown in a large area of wing disc might have a group-protection and undead-cells microenvironment that modulates the action of JNK signalling resulting in tumor formation. Furthermore, JNK dependent activation of Wnt/Ca2+ signalling also supports the tumor growth and actin cytoskeleton disruption. Thus, our results importantly highlight the role of JNK signalling in tumor progression upon scrib loss of function depending on cellular-microenvironment.

cancer biology↗