Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2015 Oct 12;211(1):159–172. doi: 10.1083/jcb.201504097

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2015 Yoshida et al.

This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).

PMC Copyright notice

Figure 8. — Signaling for mTORC1 activation is localized to macropinocytic cups. (A) BMMs expressing CFP and YFP-BtkPH, a probe for PIP₃, were imaged during M-CSF–stimulated macropinocytosis. The image series are aligned such that circular ruffle closure occurs at t = 80 s (top row). Pseudocolor ratio images (YFP-BtkPH/CFP) show strong YFP-BtkPH recruitment to the macropinocytic cup at t = 120 s (bottom row). (B) Ratiometric imaging of the DAG probe C1δ-YFP in BMMs, as described in (A). t = 80 s marks the end of ruffle closure. Maximal C1δ-YFP recruitment occurs at t = 140 and 160 s (C) Ratiometric imaging of the PIP₃ probe YFP-BtkPH during PMA-stimulated macropinocytosis. YFP-BtkPH was not recruited to the macropinocytic cup. Bars, 5 µm. (D) Two pathways of growth factor receptor (GFR) signaling to mTORC1. GFR signaling activates PI3K, which activates mTORC1 by a cytosolic pathway, involving Akt, TSC2, and Rheb, and a vesicular pathway, involving PKC-dependent, macropinosome-mediated delivery of leucine to endolysosomes. PMA activates both pathways independent of PI3K. Stimuli are indicated in blue type; inhibitors are indicated in gray type. (E) The macropinosome as a discrete unit of GFR signaling. PI3K-generated PIP₃ accumulates in macropinocytic cups (red line), activating Akt (cytosolic pathway) and PLCγ. PLCγ generates DAG in the cup, leading to PKC-dependent macropinocytosis (vesicular pathway). Extracellular solutes internalized by macropinocytosis are delivered rapidly into LAMP-1 (blue lines)–enriched endolysosomes by piranhalysis or after tubular endolysosomes wrap around macropinosomes. Small solutes exchange more rapidly between macropinosomes and endolysosomes than large solutes, providing a rapid mechanism for activation of mTORC1 by amino acids inside macropinosomes and endolysosomes.