NCBI Summary:
The protein encoded by this gene is a member of the RAS superfamily which are small GTP/GDP-binding proteins with an average size of 200 amino acids. The RAS-related proteins of the RAB/YPT family may play a role in the transport of proteins from the endoplasmic reticulum to the Golgi and the plasma membrane. This protein shares 97%, 96%, and 51% similarity with the dog RAB8, mouse MEL, and mouse YPT1 proteins, respectively and contains the 4 GTP/GDP-binding sites that are present in all the RAS proteins. The putative effector-binding site of this protein is similar to that of the RAB/YPT proteins. However, this protein contains a C-terminal CAAX motif that is characteristic of many RAS superfamily members but which is not found in YPT1 and the majority of RAB proteins. Although this gene was isolated as a transforming gene from a melanoma cell line, no linkage between MEL and malignant melanoma has been demonstrable. This oncogene is located 800 kb distal to MY09B on chromosome 19p13.1. [provided by RefSeq, Jul 2008]
General function
Intracellular signaling cascade
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Oocyte maturation
Comment
RAB8A GTPase regulates spindle migration and Golgi apparatus distribution via ROCK-mediated actin assembly in mouse oocyte meiosis. Pan ZN et al. (2018) Actin filaments are widely involved in multiple cellular processes in oocyte meiosis, such as spindle migration and polar body extrusion. The actin nucleators like Arp2/3 complex and formins are the most recognized molecules for actin assembly in oocytes. In the present study, we report that the vesicle trafficking factor, RAB8A GTPase, is a new regulator critical for actin assembly in meiosis. Our results showed that RAB8A was localized at both the spindle periphery and cortex in mouse oocytes, which was similar to the localization patterns of actin filaments. RAB8A depletion caused spindle migration defects and the failure of polar body extrusion, which could have been due to decreases in both cytoplasmic and cortical actin filaments in oocytes. Based on mass spectrometry analysis, we showed that RAB8A promoted actin assembly through its modulation on the ROCK-LIMK signaling pathway. Moreover, we demonstrated that RAB8A colocalized and interacted with GM130 at the spindle periphery and that RAB8A depletion caused the disruption of GM130-docked Golgi distribution. Taken together, our data indicated that RAB8A was required for Golgi distribution, spindle migration, and polar body extrusion via ROCK-mediated actin assembly in mouse oocyte meiosis.//////////////////