Related Experiment Video
Updated: Jan 8, 2026
Pulmonary Embolism III: Nursing Management
Published on: June 19, 2025
The CPEB translational regulator, Orb, functions together with Par proteins to polarize the Drosophila oocyte
Justinn Barr1, Sofia Charania1, Rudolf Gilmutdinov2
1Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America.
Abstract:
orb is a founding member of the CPEB family of translational regulators and is required at multiple steps during Drosophila oogenesis. Previous studies showed that orb is required during mid-oogenesis for the translation of the posterior/germline determinant oskar mRNA and the dorsal-ventral determinant gurken mRNA. Here, we report that orb also functions upstream of these axes determinants in the polarization of the microtubule network (MT). Prior to oskar and gurken translational activation, the oocyte MT network is repolarized. The MT organizing center at the oocyte posterior is disassembled, and a new MT network is established at the oocyte anterior. Repolarization depends upon cross-regulatory interactions between anterior (apical) and posterior (basal) Par proteins. We show that repolarization of the oocyte also requires orb and that orb is needed for the proper functioning of the Par proteins. orb interacts genetically with aPKC and cdc42 and in egg chambers compromised for orb activity, Par-1 and aPKC protein and aPKC mRNA are mislocalized. Moreover, like cdc42-, the defects in Par protein localization appear to be connected to abnormalities in the cortical actin cytoskeleton. These abnormalities also disrupt the localization of the spectraplakin Shot and the microtubule minus-end binding protein Patronin. These two proteins play a critical role in the repolarization of the MT network.
Insights
The Orb protein is crucial for establishing cell polarity in Drosophila oocytes by regulating microtubule network repolarization. It ensures proper localization of key proteins, which is essential for axis determination.
Area of Science:
- Developmental Biology
- Cell Biology
- Genetics
Background:
- Orb is a key translational regulator in the CPEB family, vital for Drosophila oogenesis.
- Previous research highlighted Orb's role in translating oskar and gurken mRNAs during mid-oogenesis.
- The establishment of embryonic axes relies on precise protein localization and cellular organization.
Purpose of the Study:
- To investigate the role of Orb in the early polarization of the microtubule network in Drosophila oocytes.
- To understand how Orb influences the function of Par proteins in establishing anterior-posterior and dorsal-ventral axes.
- To elucidate the molecular mechanisms linking Orb to microtubule repolarization and cytoskeletal organization.
Main Methods:
- Genetic interaction studies involving Orb, aPKC, and cdc42.
- Analysis of protein and mRNA localization in Orb-compromised egg chambers.
- Examination of the cortical actin cytoskeleton and localization of Shot and Patronin.
Main Results:
- Orb is required upstream of oskar and gurken for microtubule network repolarization.
- Orb is essential for the proper functioning of anterior-posterior patterning (Par) proteins.
- Defects in Orb activity lead to mislocalization of Par-1 and aPKC, and disrupt actin cytoskeleton organization.
Conclusions:
- Orb plays a critical role in the early polarization of the oocyte microtubule network.
- Orb's function is integrated with the Par protein network and cytoskeletal organization for axis determination.
- Proper Orb function is necessary for the localization of Shot and Patronin, which are critical for microtubule repolarization.
Related Concept Videos
01:27Pulmonary Embolism III: Nursing Management
01:29Pulmonary Embolism II: Diagnostic Studies and Interprofessional Care
01:29Pulmonary Embolism I: Introduction
01:29Venous Thrombosis III: Interprofessional Care
01:27Pneumothorax-II
Clinical Manifestations:
01:29Chronic Obstructive Pulmonary Disease-V: Management
Smoking Cessation