Biology subjects

Monroy, B. Y.

Publications and source records attributed to Monroy, B. Y..

4 recordsLinked to original sources

bioRxiv2025

Structure and mechanism of microtubule stabilization and motor regulation by MAP9

Microtubule-associated proteins (MAPs) regulate the organization of microtubules and control intracellular transport, but their individual contributions to microtubule dynamics and motor regulation remain poorly understood. Here, we identify MAP9 as a critical factor that stabilizes microtubules and facilitates neuronal morphogenesis. MAP9 knockdown abolishes the outgrowth of neurites, a phenotype not observed through the loss of other neuronal MAPs. Cryo-electron microscopy revealed that, unlike other MAPs that bind along protofilaments, MAP9 binds around the microtubule as a long alpha helix using five consecutive repeats. This unique binding mode enables MAP9 to staple adjacent protofilaments, thereby preventing microtubule depolymerization. We also showed that MAP9 selectively permits kinesin-3 and dynein motility while hindering kinesin-1 through interactions with a divergent loop-8 of the kinesin motor domain. Our results establish MAP9 as a key MAP required for neuronal growth and uncover how it differentially regulates intracellular transport driven by kinesin motors.

biophysics↗

bioRxiv2021

Expression Atlas of Avian Neural Crest Proteins: Neurulation to Migration

Neural crest (NC) cells are a dynamic population of embryonic stem cells that create various adult tissues in vertebrate species including craniofacial bone and cartilage and the peripheral and enteric nervous systems. NC development is a conserved and complex process that is controlled by a tightly regulated gene regulatory network (GRN) of morphogens, transcription factors, and cell adhesion proteins. While multiple studies have characterized the expression of several GRN factors in single species, a comprehensive protein analysis that directly compares expression across development is lacking. To address this, we used three closely related avian models, Gallus gallus (chicken), Coturnix japonica (Japanese quail), and Pavo cristatus (Indian peafowl), to compare the localization and timing of four GRN transcription factors, PAX7, SOX9, SNAI2, and SOX10 from the onset of neurulation to migration. While the spatial expression of these factors is largely conserved, we find that quail NC cells express SOX9, SNAI2, and SOX10 proteins at the equivalent of earlier developmental stages than chick and peafowl. In addition, quail NC cells migrate farther and more rapidly than the larger organisms. These data suggest that despite a conservation of NC GRN players, differences in the timing of NC development between species remain a significant frontier to be explored with functional studies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/456488v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@1d4210corg.highwire.dtl.DTLVardef@1c5d743org.highwire.dtl.DTLVardef@1b78d56org.highwire.dtl.DTLVardef@1a04059_HPS_FORMAT_FIGEXP M_FIG Comparative analysis of neural crest (NC) protein spatiotemporal localization in quail, chick, and peafowl embryos. Avian embryos were incubated for different lengths of time to achieve the same developmental stage marked by somite number (somite stage, SS) as described by Hamburger and Hamilton (HH) in 1951. (A) Quail, (B) chick, and (C) peafowl embryos were collected for immunohistochemistry (IHC) to define and quantify the timeline of NC protein expression. We specifically focused on the expression of PAX7, SNAI2, SOX9, and SOX10 proteins. We determined that neural crest development as marked by common NC-specific proteins differs between species. Rather than similar, but scaled development, each organism has its own NC developmental timeline. Quail embryos develop much more rapidly than their counterparts, chick and peafowl. Further, chick and peafowl amino acid sequences are more similar to each other than they are to quail. C_FIG

developmental biology↗

bioRxiv2019

A Combinatorial MAP Code Dictates Polarized Microtubule Transport

Many eukaryotic cells distribute their intracellular components through asymmetrically regulated active transport driven by molecular motors along microtubule tracks. While intrinsic and extrinsic regulation of motor activity exists, what governs the overall distribution of activated motor-cargo complexes within cells remains unclear. Here, we utilize in vitro reconstitution of purified motor proteins and non-enzymatic microtubule-associated proteins (MAPs) to demonstrate that these MAPs exhibit distinct influences on the motility of the three main classes of transport motors: kinesin-1, kinesin-3, and cytoplasmic dynein. Further, we dissect how combinations of MAPs affect motors, and reveal how transient interactions between MAPs and motors may promote these effects. From these data, we propose a general \"MAP code\" that has the capacity to strongly bias directed movement along microtubules and helps elucidate the intricate intracellular sorting observed in highly polarized cells such as neurons.

biophysics↗

bioRxiv2017

Competition between microtubule-associated proteins directs motor transport

Within cells, numerous motor and non-motor microtubule-associated proteins (MAPs) simultaneously converge on the microtubule lattice. How the binding activities of non-motor MAPs are coordinated and how they contribute to the balance and distribution of microtubule motor transport is unknown. Here, we examine the relationship between MAP7 and tau due to their antagonistic effects on neuronal branch formation and kinesin motility in vivo1-8. We find that MAP7 and tau compete for binding to microtubules, and determine a mechanism by which MAP7 displaces tau from the lattice. In striking contrast to the inhibitory effect of tau, MAP7 promotes kinesin-based transport in vivo and strongly enhances kinesin-1 binding to the microtubule in vitro, providing evidence for direct enhancement of motor motility by a MAP. In contrast, both MAP7 and tau strongly inhibit kinesin-3 and have no effect on cytoplasmic dynein, demonstrating that MAPs exhibit differential control over distinct classes of motors. Overall, these results reveal a general principle for how MAP competition dictates access to the microtubule to determine the correct distribution and balance of molecular motor activity.

cell biology↗