Biology subjects

Rishal, I.

Publications and source records attributed to Rishal, I..

5 recordsLinked to original sources

bioRxiv2026

Multiple mTOR RNA localization signals regulate subcellular protein synthesis and axonal growth

Subcellular localization of mTOR is thought to be key for regulating cell size and growth, but the relative contributions of mRNA versus protein localization are unclear. We used reporter mRNA localization assays to identify two distinct mTOR Localizing Sequences (MLS) in its 5UTR, in addition to the localization activity already reported for the 3UTR. Gene-edited mice with deletion of both 5UTR MLS are mTOR hypomorphs with reduced body weight and brain size. In contrast, a mouse line lacking the second 5UTR MLS and the 3UTR retains near normal overall mTOR expression levels with specific subcellular perturbation of mTOR localization to neuronal axons. This subcellular mTOR deficit affects axonal local protein synthesis and neuronal growth. Thus, mTOR transcripts are localized by multiple UTR sequences, and subcellular localization of mTOR mRNA regulates local protein synthesis and neuronal growth.

neuroscience↗

bioRxiv2022

A new monoclonal antibody enables BAR analysis of subcellular importin β1 interactomes

Importin {beta}1 (KPNB1) is a nucleocytoplasmic transport factor with critical roles in both cytoplasmic and nucleocytoplasmic transport, hence there is keen interest in the characterization of its subcellular interactomes. We found limited efficiency of BioID in detection of importin complex cargos, and therefore generated a highly specific and sensitive anti-KPNB1 monoclonal antibody to enable Biotinylation by Antibody Recognition (BAR) analysis of importin {beta}1 interactomes. The monoclonal antibody recognizes an epitope comprising residues 301-320 of human KPBN1, and strikingly is highly specific for cytoplasmic KPNB1 in diverse applications, with little or no reaction with KPNB1 in the nucleus. BAR with this novel antibody revealed numerous new interactors of importin {beta}1, expanding the KPNB1 interactome to cytoplasmic and signaling complexes that highlight potential new functions for the importins complex beyond nucleocytoplasmic transport. Data are available via ProteomeXchange with identifier PXD032728.

neuroscience↗

bioRxiv2022

A conditional null allele of Dync1h1 enables targeted analyses of dynein roles in neuronal length sensing and neurological disorders

Size homeostasis is one of the most fundamental aspects of biology and it is particularly important for large cells as neurons. We have previously proposed a motor-dependent length-sensing and growth-regulating mechanism wherein a partial reduction in the levels of microtubule motor proteins should lead to accelerated neuronal growth. This prediction was originally validated in sensory neurons heterozygous for the Loa point mutation in dynein heavy chain 1 (Dync1h1Loa). Here we describe a new mouse model with a conditional allele allowing deletion of exons 24-25 in Dync1h1. Homozygous Islet1-Cre deletion of Dync1h1 is embryonic lethal, but heterozygous animals (Isl1-Dync1h1+/-) survive to adulthood with approximately 50% dynein expression in targeted cell types. Isl1-Dync1h1+/- adult sensory neurons reveal an accelerated growth phenotype, similar to that previously reported in Dync1h1Loa neurons. Moreover, Isl1-Dync1h1+/- mice show mild impairments in gait, proprioception and tactile sensation; and slightly impaired recovery from peripheral nerve injury. Thus, conditional deletion of Dync1h1 exons 24-25 enables targeted studies of the role of dynein in neuronal growth and neurological disorders.

neuroscience↗

bioRxiv2020

PTBP1 Regulates Injury Responses and Sensory Pathways in Adult Peripheral Neurons

Polypyrimidine Tract Binding Protein 1 (PTBP1) is expressed only at embryonic stages in central neurons. Its downregulation triggers neuronal differentiation in precursor and non-neuronal cells, an approach recently used to generate neurons de novo for amelioration of neurodegenerative disorders. Moreover, PTBP1 is replaced by its paralog PTBP2 in mature central neurons. Surprisingly, we found both proteins co-expressed in adult sensory and motor neurons, with PTBP2 restricted mainly to the nucleus, while PTBP1 shows strong axonal localization. Levels of axonal PTBP1 increased markedly after peripheral nerve injury, and its cargos include mRNAs involved in axonal growth and regeneration, such as importin {beta}1 and RhoA. Perturbation of PTBP1 affects neuronal injury responses, axon outgrowth and sensation in vivo. Thus, PTBP1 has roles in sensory function and regenerative capacity of adult sensory neurons. These findings suggest that caution may be required before considering targeting PTBP1 for therapeutic purposes.

neuroscience↗

bioRxiv2019

DYNLRB1 is Essential for Dynein Mediated Transport and Neuronal Survival

The cytoplasmic dynein motor complex transports essential signals and organelles from the cell periphery to perinuclear region, hence is critical for the survival and function of highly polarized cells such as neurons. Dynein Light Chain Roadblock-Type 1 (DYNLRB1) is thought to be an accessory subunit required for specific cargos, but here we show that it is essential for general dynein-mediated transport and sensory neuron survival. Homozygous Dynlrb1 null mice are not viable and die during early embryonic development. Furthermore, heterozygous or adult knockdown animals display reduced neuronal growth, and selective depletion of Dynlrb1 in proprioceptive neurons compromises their survival. Conditional depletion of Dynlrb1 in sensory neurons causes deficits in several signaling pathways, including {beta}-catenin subcellular localization, and a severe impairment in the axonal transport of both lysosomes and retrograde signaling endosomes. Hence, DYNLRB1 is an essential component of the dynein complex.

neuroscience↗