Biology subjects

Deb Roy, A.

Publications and source records attributed to Deb Roy, A..

4 recordsLinked to original sources

bioRxiv2024

Optogenetically Induced Microtubule Acetylation Unveils the Molecular Dynamics of Actin-Microtubule Crosstalk in Directed Cell Migration

Microtubule acetylation is implicated in regulating cell motility, yet its physiological role in directional migration and the underlying molecular mechanisms have remained unclear. This knowledge gap has persisted primarily due to a lack of tools capable of rapidly manipulating microtubule acetylation in actively migrating cells. To overcome this limitation and elucidate the causal relationship between microtubule acetylation and cell migration, we developed a novel optogenetic actuator, optoTAT, which enables precise and rapid induction of microtubule acetylation within minutes in live cells. Using optoTAT, we observed striking and rapid responses at both molecular and cellular level. First, microtubule acetylation triggers release of the RhoA activator GEF-H1 from sequestration on microtubules. This release subsequently enhances actomyosin contractility and drives focal adhesion maturation. These subcellular processes collectively promote sustained directional cell migration. Our findings position GEF-H1 as a critical molecular responder to microtubule acetylation in the regulation of directed cell migration, revealing a dynamic crosstalk between the actin and microtubule cytoskeletal networks.

cell biology↗

bioRxiv2023

Non-catalytic role of phosphoinositide 3-kinase in mesenchymal cell migration through non-canonical induction of p85beta/AP-2-mediated endocytosis

Class IA phosphoinositide 3-kinase (PI3K) galvanizes fundamental cellular processes such as migration, proliferation, and differentiation. To enable multifaceted roles, the catalytic subunit p110 utilizes a multi- domain, regulatory subunit p85 through its inter SH2 domain (iSH2). In cell migration, their product PI(3,4,5)P3 generates locomotive activity. While non-catalytic roles are also implicated, underlying mechanisms and its relationship to PI(3,4,5)P3 signaling remain elusive. Here, we report that a disordered region of iSH2 contains previously uncharacterized AP-2 binding motifs which can trigger clathrin and dynamin-mediated endocytosis independent of PI3K catalytic activity. The AP-2 binding motif mutants of p85 aberrantly accumulate at focal adhesions and upregulate both velocity and persistency in fibroblast migration. We thus propose the dual functionality of PI3K in the control of cell motility, catalytic and non- catalytic, arising distinctly from juxtaposed regions within iSH2.

cell biology↗

bioRxiv2022

Multiple Ciliary Localization Signals Control INPP5E Ciliary Targeting

Primary cilia are sensory membrane protrusions whose dysfunction causes diseases named ciliopathies. INPP5E is a ciliary phosphoinositide phosphatase mutated in ciliopathies like Joubert syndrome. INPP5E regulates numerous ciliary functions, such as cilium stability, trafficking, signaling, or exovesicle release. Despite its key ciliary roles, how INPP5E accumulates in cilia remains poorly understood. Herein, we show that INPP5E ciliary targeting requires its folded catalytic domain and is controlled by four ciliary localization signals (CLSs), the first two of which we newly discover: LLxPIR motif (CLS1), W383 (CLS2), FDRxLYL motif (CLS3) and CaaX box (CLS4). We answer two long-standing questions in the field. First, partial redundancy between CLS1 and CLS4 explains why CLS4 is dispensable for ciliary targeting. Second, the essential need for CLS2 on the catalytic domain surface clarifies why CLS3 and CLS4 are together insufficient for ciliary accumulation. Furthermore, we reveal that some Joubert syndrome mutations in INPP5E catalytic domain affect its ciliary targeting, and shed light on the mechanisms of action of each CLS. Thus, we find that CLS2 and CLS3 promote interaction with TULP3 and ARL13B, while downregulating CEP164 binding. On the other hand, CLS4 recruits PDE6D, RPGR and ARL13B, and cooperates with CLS1 in ATG16L1 binding. Lastly, we show INPP5E immune synapse targeting is CLS-independent. Altogether, we reveal unusual complexity in INPP5E ciliary targeting mechanisms, likely reflecting its multiple key roles in ciliary biology.

cell biology↗

bioRxiv2020

A phospho-regulated ensemble signal motif of α-TAT1 drives dynamic microtubule acetylation

Spatiotemporally dynamic microtubule acetylation underlies diverse physiological events ranging from cell migration to intracellular trafficking, autophagy and viral infections. Despite its ubiquity, the molecular mechanisms that regulate the sole microtubule acetylating agent, -tubulin N-acetyltransferase 1 (-TAT1) remain obscure. Here we report that dynamic intracellular localization of -TAT1 unexpectedly determines the efficiency of microtubule acetylation. Specifically, we newly identified a conserved signal motif in the intrinsically disordered C-terminus of -TAT1, consisting of three competing regulatory elements - nuclear export, nuclear import and cytosolic retention. Their balance is tuned via phosphorylation by serine-threonine kinases including CDK1 and CK2. While the un-phosphorylated form resides both in the cytosol and nucleus, the phosphorylated form binds to specific 14-3-3 adapters and accumulates in the cytosol for maximal substrate access. Cytosolic localization of -TAT1 predominantly mediates microtubule acetylation, cell proliferation and DNA damage response. In contrast to other molecules with a similar phospho-regulated signal motif including transcription factors, -TAT1 uniquely uses the nucleus as a hideout. As amino acid mutations to the motif have been reported in cancer patients, the present mechanism of subcellular -TAT1 localization may help uncover a spatiotemporal code of microtubule acetylation in normal and aberrant cell functions.

cell biology↗