Decoding MTSS2 phosphoregulation: its role in cytoskeletal dynamics and clinical implications.

Simple SummaryGlioma is a tumor originating from cells supporting the brain and represents a major health challenge. Palladin is a structural protein widely expressed in mammalian tissues and has a pivotal role in cytoskeletal dynamics in health and disease. Palladin is linked to the progression of breast, pancreatic, and renal cancers. However, the role of palladin in gliomas is yet unknown. In this work, we aimed to shed light on palladin’s role in glioma tumors using publicly available data, along with samples obtained from humans and mice. Our findings indicate that palladin expression might be linked to adult glioma progression and is associated with a worse prognosis. Overall, our results introduce the possibility of using palladin as a diagnostic and prognostic marker, as well as a potential future therapeutic target.Brain tumors comprise over 100 types of masses, differing in the following: location; patient age; molecular, histological, and immunohistochemical characteristics; and prognosis and treatment. Glioma tumors originate from neuroglia, cells supporting the brain. Palladin, a structural protein widely expressed in mammalian tissues, has a pivotal role in cytoskeletal dynamics and motility in health and disease. Palladin is linked to the progression of breast, pancreatic, and renal cancers. In the central nervous system, palladin is involved in embryonic development, neuronal maturation, the cell cycle, differentiation, and apoptosis. However, the role of palladin in brain tumors is unknown. In this work, we explored palladin’s role in glioma. We analyzed clinical data, along with bulk and single-cell gene expression. We then validated our results using IHC staining of tumor samples, together with qRT-PCR of glioma cell lines. We determined that wild-type palladin-4 is overexpressed in adult gliomas and is correlated with a decrease in survival. Palladin expression outperformed clinically used prognostic markers and was most prominent in glioblastoma. Finally, we showed that palladin originates from the malignant cell population. Our findings indicate that palladin expression might be linked to adult glioma progression and is associated with prognosis.

Data Concordance from a Comparison between Filter Binding and Fluorescence Polarization Assay Formats for Identification of ROCK-II Inhibitors

Abstract: The cytoskeleton, which mainly consists of microtubules (MTs) and actin microfilaments (MFs), plays various significant roles that are indispensable for eukaryotic viability, including determination of cell shape, cell movement, nuclear division, and cytokinesis. In animal cells, MFs appear to be of more importance than MTs, except for spindle formation in nuclear division. In contrast, higher plants have a rigid cell wall around their cells, and have thus evolved elegant systems of MTs to control the direction of cellulose microfibrils (CMFs) deposited in the cell wall, and to divide centrifugally in a physically limited space. Dynamic changes in MTs during cell cycle progression in higher plant cells have been observed over several decades, including cortical MTs (CMTs) during interphase, preprophase bands (PPBs) from late G2 phase to prophase, spindles from prometaphase to anaphase, and phragmoplasts at telophase. The MFs also show some changes not as obvious as MT dynamics. However, questions regarding the process of formation of these arrays, and the precise mechanisms by which they fulfill their roles, remain unsolved. In this article, we present an outline of the changes in the cytoskeleton based on our studies with highly‐synchronized tobacco BY‐2 cells. Some candidate molecules that could play roles in cytoskeletal dynamics are discussed. We also hope to draw attention to recent attempts at visualization of cytoskeletons with molecular techniques, and to some examples of genetic approaches in this field.

The cerebral cortex is an intricately organized brain structure responsible for high-level functions including sensory perception, movement, memory, language, and cognition. During corticogenesis, cortical excitatory neurons and inhibitory interneurons migrate from their respective progenitor zones into the developing cerebral cortex, deposit in the correct cortical layer, and establish connections with their appropriate synaptic partners. The balance between excitation and inhibition is critical for cortical circuitry development and function. Aberrant migration of inhibitory interneurons can alter the formation of cortical circuitry and lead to several neurodevelopmental disorders including epilepsy, autism spectrum disorder, and schizophrenia. Therefore, elucidating the mechanisms responsible for inhibitory interneuron migration will provide greater insight into the development of these diseases. This dissertation explores the role of c-Jun NH2-terminal kinase (JNK) signaling pathway in the cellular mechanisms required for the guided migration of cortical interneurons. In Chapter 2, I used live-cell confocal microscopy to explore the mechanisms by which JNK activity coordinates two cell biological processes that are essential for the guided migration of cortical interneurons: nucleokinesis and leading process branching. I found that pharmacological inhibition and genetic ablation of JNK-signaling in cortical interneurons impairs the kinetics of nucleokinesis. Moreover, JNK signaling controls the subcellular localization of the centrosome and primary cilium, two organelles involved in nucleokinesis. To orient their direction of migration, cortical interneurons extend and retract leading process branches to respond to chemotactic guidance cues present in their environments. Both pharmacological inhibition and genetic removal of JNK disrupted the stability of leading process branches, resulting in decreased frequency of growth cone splits and the shortened duration of interstitial side branches. In Chapter 3, I explored the role of JNK signaling in nucleokinesis of interneurons migrating in different substrate and topographical environments and found that cortical interneurons have an intrinsic requirement for JNK signaling during nucleokinesis regardless of substrate environment. Moreover, I found that interneurons can use nanoscale features in their environment to orient their direction of migration. Additionally, cortical interneurons aligned on a nanopattern topography have a highly polarized subcellular localization of doublecortin, a substrate of JNK involved in microtubule stability. Together, these are the first studies examining the role of JNK signaling in the cellular mechanisms controlling cortical interneuron migration and provide novel insight into the roles of JNK in cortical inhibitory interneuron development. Future efforts should be aimed at unraveling the mechanism through which JNK controls interneuron migration by exploring JNK’s role in cytoskeletal dynamics

Identification of DUOX1-dependent redox signaling through protein S-glutathionylation in airway epithelial cells

Palladin's Ig4 Mutation: Exploring the Link with Pancreatic Cancer

p49/STRAP, a Serum Response Factor Binding Protein (SRFBP1), Is Involved in the Redistribution of Cytoskeletal F-Actin Proteins during Glucose Deprivation.

Actin-depolymerizing factors (ADFs) play crucial roles in cytoskeletal dynamics and stress adaptation in plants. In this study, we identified nine ADF genes (TbADF1 to TbADF9) in Triticum monococcum L. subsp. aegilopoides. Chromosomal distribution analysis revealed that these genes are unevenly distributed across five chromosomes, with evidence of tandem duplication events. Phylogenetic analysis clustered the TbADFs into four subfamilies, indicating evolutionary conservation among wheat relatives. Gene structure and motif analyses confirmed the presence of a conserved ADF domain. Additionally, promoter region analysis revealed a variety of cis-regulatory elements associated with hormone signaling and stress responses. Predictions of binding pockets and protein-protein interaction networks indicated potential functional sites and interactions with cytoskeletal regulators. Codon usage bias analysis showed a preference for GC-rich codons, which may enhance translation efficiency under stress. Codon usage bias analysis indicated GC-rich optimization, potentially enhancing translation efficiency under stress. Promoter methylation levels ranged from 0.0907 to 0.3053, suggesting that epigenetic regulation may contribute to the control of gene expression. Transcriptomic profiling across six tissues and under cold stress conditions (4°C for 24 hours) revealed both tissue-specific expression patterns and differential cold responses. Notably, TbADF1, TbADF4, TbADF6, and TbADF7 were upregulated, with TbADF6 exhibiting the strongest induction, as its TPM value increased from 29.07 to 300.01. Furthermore, co-expression and gene ontology enrichment analyses of the upregulated genes identified key biological pathways involved in membrane integrity, phosphorylation, ribosome maturation, and lipid signaling. These findings highlight the central role of TbADF6 in cold adaptation.

Mutations in the LRRK2 (leucine-rich repeat kinase 2) gene on chromosome 12 cause autosomal dominant PD (Parkinson's disease), which is indistinguishable from sporadic forms of the disease. Numerous attempts have therefore been made to model PD in rodents via the transgenic expression of LRRK2 and its mutant variants and to elucidate the function of LRRK2 by knocking out rodent Lrrk2. Although these models often only partially recapitulate PD pathology, they have helped to elucidate both the normal and pathological function of LRRK2. In particular, LRRK2 has been suggested to play roles in cytoskeletal dynamics, synaptic machinery, dopamine homoeostasis and autophagic processes. Our understanding of how these pathways are affected, their contribution towards PD development and their interaction with one another is still incomplete, however. The present review summarizes the findings from LRRK2 rodent models and draws potential connections between the apparently disparate cellular processes altered, in order to better understand the underlying mechanisms of LRRK2 dysfunction and illuminate future therapeutic interventions.

Actin polymerization is a fundamental cellular process regulating immune cell functions and the immune response. The Wiskott-Aldrich syndrome protein (WASp) is an actin nucleation promoting factor, which is exclusively expressed in hematopoietic cells, where it plays a key regulatory role in cytoskeletal dynamics. WASp interacting protein (WIP) was first discovered as the binding partner of WASp, through the use of the yeast two hybrid system. WIP was later identified as a chaperone of WASp, necessary for its stability. Mutations occurring at the WASp homology 1 domain (WH1), which serves as the WIP binding site, were found to cause the Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). WAS manifests as an immune deficiency characterized by eczema, thrombocytopenia, recurrent infections, and hematopoietic malignancies, demonstrating the importance of WIP for WASp complex formation and for a proper immune response. WIP deficiency was found to lead to different abnormalities in the activity of various lymphocytes, suggesting differential cell-dependent roles for WIP. Additionally, WIP deficiency causes cellular abnormalities not found in WASp-deficient cells, indicating that WIP fulfills roles beyond stabilizing WASp. Indeed, WIP was shown to interact with various binding partners, including the signaling proteins Nck, CrkL and cortactin. Recent studies have demonstrated that WIP also takes part in non immune cellular processes such as cancer invasion and metastasis, in addition to cell subversion by intracellular pathogens. Understanding of numerous functions of WIP can enhance our current understanding of activation and function of immune and other cell types.

RhoF GTPase Transcription Is Upregulated in Germinal Center B-Cells, Shows Altered Expression in Malignant B-Cells, and Interacts with the ATM Pathway.

Fluorescent measurement of desmin intermediate filament assembly

The subcellular localization, together with the expression level, determines the biological effects and physiological functions of proteins. Fidgetin (FIGN) is a microtubule-severing protein that plays a critical role in cytoskeletal dynamics, and it predominantly localizes in the nucleus in normal cells. Here, we observed FIGN largely in the cytoplasm of malignant cells, and increased cytoplasmic FIGN was significantly associated with clinicopathological features and poor prognosis in breast carcinoma, hepatocellular carcinoma and lung adenocarcinoma. Cytoplasmic FIGN promoted tumor development, growth, and metastasis in multiple mouse models, and it facilitated proliferation, colony formation, migration, and invasion of multiple cancer cells in vitro. FIGN interacted with MYH2 and HNRNPA2B1; MYH2 regulated the nucleocytoplasmic distribution of FIGN and its effects on cancer progression, while cytoplasmic FIGN stabilized β-catenin mRNA and promoted malignant biological behaviors in an HNRNPA2B1-dependent manner. Furthermore, an iRGD-fused peptide was designed to block the MYH2-FIGN interface, which facilitated FIGN translocation to the nucleus and suppressed cancer progression. Together, this study demonstrates a noncanonical mechanism for β-catenin activation by cytoplasmic FIGN that drives cancer progression.

Some of the characteristics of cancer cells are high rates of cell proliferation, cell survival, and the ability to invade surrounding tissue. The cytoskeleton has an essential role in these processes. Dynamic changes in the cytoskeleton are necessary for cell motility and cancer cells are dependent on motility for invasion and metastasis. The signaling pathways behind the reshaping and migrating properties of the cytoskeleton in cancer cells involve a group of Ras-related small GTPases and their effectors, including the p21-activated kinases (Paks). Paks are a family of serine/threonine protein kinases comprised of six isoforms (Pak 1-6), all of which are direct targets of the small GTPases Rac and Cdc42. Besides their role in cytoskeletal dynamics, Paks have recently been shown to regulate various other cellular activities, including cell survival, mitosis, and transcription. Paks are overexpressed and/or hyperactivated in several human tumors and their role in cell transformation makes them attractive therapeutic targets. Pak-targeted therapeutics may efficiently inhibit certain types of tumors and efforts to identify selective Pak-inhibitors are underway.

Progress and challenges in the use of Cofilin-1 as a prognostic and predictive biomarker for cancer management.