The formin INF2 regulates basolateral-to-apical transcytosis and lumen formation in association with Cdc42 and MAL2.
Transcytosis is a widespread pathway for apical targeting in epithelial cells. MAL2, an essential protein of the machinery for apical transcytosis, functions by shuttling in vesicular carriers between the apical zone and the cell periphery. We have identified INF2, an atypical formin with actin polymerization and depolymerization activities, which is a binding partner of MAL2. MAL2-positive vesicular carriers associate with short actin filaments during transcytosis in a process requiring INF2. INF2 binds Cdc42 in a GTP-loaded-dependent manner. Cdc42 and INF2 regulate MAL2 dynamics and are necessary for apical transcytosis and the formation of lateral lumens in hepatoma HepG2 cells. INF2 and MAL2 are also essential for the formation of the central lumen in organotypic cultures of epithelial MDCK cells. Our results reveal a functional mechanism whereby Cdc42, INF2, and MAL2 are sequentially ordered in a pathway dedicated to the regulation of transcytosis and lumen formation.
Madrid
Ricardo
R
Centro de Biología Molecular Severo Ochoa, CSIC/UAM, Cantoblanco, 28049 Madrid, Spain. ricardo-m@cbm.uam.es
Aranda
Juan F
JF
Rodríguez-Fraticelli
Alejo E
AE
Ventimiglia
Leandro
L
Andrés-Delgado
Laura
L
Shehata
Mona
M
Fanayan
Susan
S
Shahheydari
Hamideh
H
Gómez
Sergio
S
Jiménez
Alberto
A
Martín-Belmonte
Fernando
F
Byrne
Jennifer A
JA
Alonso
Miguel A
MA
D000199:Actins / Q000235:genetics / Q000378:metabolism; D001646:Bile / Q000166:cytology / Q000502:physiology; D016764:Cell Polarity; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology*; D000080865:Formins; D017930:Genes, Reporter; D000077614:Golgi Matrix Proteins; D056945:Hep G2 Cells / Q000166:cytology / Q000502:physiology; D022781:Hepatocytes / Q000166:cytology* / Q000502:physiology*; D008840:Microfilament Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D062806:Myelin and Lymphocyte-Associated Proteolipid Proteins; D011510:Proteolipids / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D033921:Vesicular Transport Proteins / Q000378:metabolism* / Q000502:physiology*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*
D000199:Actins; D000080865:Formins; D000077614:Golgi Matrix Proteins; C546959:INF2 protein, human; C438606:MAL2 protein, human; D008840:Microfilament Proteins; D062806:Myelin and Lymphocyte-Associated Proteolipid Proteins; D011510:Proteolipids; D034741:RNA, Small Interfering; D033921:Vesicular Transport Proteins; C091580:vesicular transport factor p115; D020764:cdc42 GTP-Binding Protein