Kinesins Modify ERR1-Dependent Transcription Using a Conserved Nuclear Receptor Box Motif.

Kinesin family motors are microtubule (MT)-stimulated ATPases known best as transporters of cellular cargoes through the cytoplasm, regulators of MT dynamics, organizers of the mitotic spindle, and for insuring equal division of DNA during mitosis. Several kinesins have also been shown to regulate transcription by interacting with transcriptional cofactors and regulators, nuclear receptors, or with specific promotor elements on DNA. We previously showed that an LxxLL nuclear receptor box motif in the kinesin-2 family motor KIF17 mediates binding to the orphan nuclear receptor estrogen related receptor alpha (ERR1) and is responsible for the suppression of ERR1-dependent transcription by KIF17.

Interaction of ARRDC4 With GLUT1 Mediates Metabolic Stress in the Ischemic Heart.

Background: An ancient family of arrestin-fold proteins, termed alpha-arrestins, may have conserved roles in regulating nutrient transporter trafficking and cellular metabolism as adaptor proteins. One alpha-arrestin, TXNIP (thioredoxin-interacting protein), is known to regulate myocardial glucose uptake. However, the in vivo role of the related alpha-arrestin, ARRDC4 (arrestin domain-containing protein 4), is unknown.

Endothelial IQGAP1 regulates leukocyte transmigration by directing the LBRC to the site of diapedesis.

Transendothelial migration (TEM) of leukocytes across the endothelium is critical for inflammation. In the endothelium, TEM requires the coordination of membrane movements and cytoskeletal interactions, including, prominently, recruitment of the lateral border recycling compartment (LBRC). The scaffold protein IQGAP1 was recently identified in a screen for LBRC-interacting proteins.

Galectin-3 modulates the polarized surface delivery of β1-integrin in epithelial cells.

Epithelial cells require a precise intracellular transport and sorting machinery to establish and maintain their polarized architecture. This machinery includes β-galactoside-binding galectins for targeting of glycoprotein to the apical membrane. Galectin-3 sorts cargo destined for the apical plasma membrane into vesicular carriers.

G-Protein Gα Functions with Abl Kinase to Regulate Actin Cytoskeletal Reorganization.

Heterotrimeric G-proteins are essential cellular signal transducers. One of the G-proteins, Gα, is critical for actin cytoskeletal reorganization, cell migration, cell proliferation, and apoptosis. Previously, we have shown that Gα is essential for both G-protein-coupled receptor and receptor tyrosine kinase-induced actin cytoskeletal reorganization such as dynamic dorsal ruffle turnover and cell migration.

Modulation of estrogen related receptor alpha activity by the kinesin KIF17.

Estrogen-related receptor alpha (ERR1) is an orphan nuclear receptor that can bind transcriptional co-activators constitutively. ERR1 expression correlates with poor patient outcomes in breast cancer, heightening interest in this nuclear receptor as a therapeutic target. Because ERR1 has no known regulatory ligand, a major challenge in targeting its activity is to find cellular or synthetic modulators of its function.

Microtubule Motors in Establishment of Epithelial Cell Polarity.

Epithelial cells play a key role in insuring physiological homeostasis by acting as a barrier between the outside environment and internal organs. They are also responsible for the vectorial transport of ions and fluid essential to the function of many organs. To accomplish these tasks, epithelial cells must generate an asymmetrically organized plasma membrane comprised of structurally and functionally distinct apical and basolateral membranes.

KIF17 regulates RhoA-dependent actin remodeling at epithelial cell-cell adhesions.

The kinesin KIF17 localizes at microtubule plus-ends where it contributes to regulation of microtubule stabilization and epithelial polarization. We now show that KIF17 localizes at cell-cell adhesions and that KIF17 depletion inhibits accumulation of actin at the apical pole of cells grown in 3D organotypic cultures and alters the distribution of actin and E-cadherin in cells cultured in 2D on solid supports. Overexpression of full-length KIF17 constructs or truncation mutants containing the N-terminal motor domain resulted in accumulation of newly incorporated GFP-actin into junctional actin foci, cleared E-cadherin from cytoplasmic vesicles and stabilized cell-cell adhesions to challenge with calcium depletion.

Disease mutations in desmoplakin inhibit Cx43 membrane targeting mediated by desmoplakin-EB1 interactions.

Mechanisms by which microtubule plus ends interact with regions of cell-cell contact during tissue development and morphogenesis are not fully understood. We characterize a previously unreported interaction between the microtubule binding protein end-binding 1 (EB1) and the desmosomal protein desmoplakin (DP), and demonstrate that DP-EB1 interactions enable DP to modify microtubule organization and dynamics near sites of cell-cell contact. EB1 interacts with a region of the DP N terminus containing a hotspot for pathogenic mutations associated with arrhythmogenic cardiomyopathy (AC).

A biosensor of local kinesin activity reveals roles of PKC and EB1 in KIF17 activation.

We showed previously that the kinesin-2 motor KIF17 regulates microtubule (MT) dynamics and organization to promote epithelial differentiation. How KIF17 activity is regulated during this process remains unclear. Several kinesins, including KIF17, adopt compact and extended conformations that reflect autoinhibited and active states, respectively.

Atypical protein kinase Cλ is critical for growth factor receptor-induced dorsal ruffle turnover and cell migration.

Gα13, a member of the heterotrimeric G proteins, is critical for actin cytoskeletal reorganization and cell migration. Previously we have shown that Gα13 is essential for both G protein-coupled receptor and receptor tyrosine kinase-induced actin cytoskeletal reorganization such as dynamic dorsal ruffle turnover and cell migration. Ric-8A, a non-receptor guanine nucleotide exchange factor for some heterotrimeric G proteins, is critical for coupling receptor tyrosine kinases to Gα13.

Direct regulation of microtubule dynamics by KIF17 motor and tail domains.

KIF17 is a kinesin-2 family motor that interacts with EB1 at microtubule (MT) plus-ends and contributes to MT stabilization in epithelial cells. The mechanism by which KIF17 affects MTs and how its activity is regulated are not yet known. Here, we show that EB1 and the KIF17 autoinhibitory tail domain (KIF17-Tail) interacted competitively with the KIF17 catalytic motor domain (K370).

Desmosomal cadherins utilize distinct kinesins for assembly into desmosomes.

The desmosomal cadherins, desmogleins (Dsgs) and desmocollins (Dscs), comprise the adhesive core of intercellular junctions known as desmosomes. Although these adhesion molecules are known to be critical for tissue integrity, mechanisms that coordinate their trafficking into intercellular junctions to regulate their proper ratio and distribution are unknown. We demonstrate that Dsg2 and Dsc2 both exhibit microtubule-dependent transport in epithelial cells but use distinct motors to traffic to the plasma membrane.

KIF17 stabilizes microtubules and contributes to epithelial morphogenesis by acting at MT plus ends with EB1 and APC.

Epithelial polarization is associated with selective stabilization and reorganization of microtubule (MT) arrays. However, upstream events and downstream consequences of MT stabilization during epithelial morphogenesis are still unclear. We show that the anterograde kinesin KIF17 localizes to MT plus ends, stabilizes MTs, and affects epithelial architecture.

PH-domain-dependent selective transport of p75 by kinesin-3 family motors in non-polarized MDCK cells.

A key process during epithelial polarization involves establishment of polarized transport routes from the Golgi to distinct apical and basolateral membrane domains. To do this, the machinery involved in selective trafficking must be regulated during differentiation. Our previous studies showed that KIF5B selectively transports vesicles containing p75-neurotrophin receptors to the apical membrane of polarized, but not non-polarized MDCK cells.

LIM kinase 1 and cofilin regulate actin filament population required for dynamin-dependent apical carrier fission from the trans-Golgi network.

The functions of the actin cytoskeleton in post-Golgi trafficking are still poorly understood. Here, we report the role of LIM Kinase 1 (LIMK1) and its substrate cofilin in the trafficking of apical and basolateral proteins in Madin-Darby canine kidney cells. Our data indicate that LIMK1 and cofilin organize a specialized population of actin filaments at the Golgi complex that is selectively required for the emergence of an apical cargo route to the plasma membrane (PM).

Kinesin KIF4 regulates intracellular trafficking and stability of the human immunodeficiency virus type 1 Gag polyprotein.

Retroviral Gag proteins are synthesized as soluble, myristoylated precursors that traffic to the plasma membrane and promote viral particle production. The intracellular transport of human immunodeficiency virus type 1 (HIV-1) Gag to the plasma membrane remains poorly understood, and cellular motor proteins responsible for Gag movement are not known. Here we show that disrupting the function of KIF4, a kinesin family member, slowed temporal progression of Gag through its trafficking intermediates and inhibited virus-like particle production.

Leukocyte transmigration requires kinesin-mediated microtubule-dependent membrane trafficking from the lateral border recycling compartment.

Diapedesis of leukocytes across endothelial cells is a crucial step in both the innate and adaptive immune responses. Surface molecules on leukocytes and endothelial cells critical for diapedesis have been identified, but the mechanisms underlying this process are not understood. Homophilic interaction between platelet/endothelial cell adhesion molecule (PECAM) on leukocytes and PECAM at the endothelial border triggers targeted recycling of membrane from a reticulum localized close to the endothelial cell lateral border.

Polarization-dependent selective transport to the apical membrane by KIF5B in MDCK cells.

Microtubule-based vesicular transport is well documented in epithelial cells, but the specific motors involved and their regulation during polarization are largely unknown. We demonstrate that KIF5B mediates post-Golgi transport of an apical protein in epithelial cells, but only after polarity has developed. Time-lapse imaging of EB1-GFP in polarized MDCK cells showed microtubule plus ends growing toward the apical membrane, implying that plus end-directed N-kinesins might be used to transport apical proteins.

G proteins G12 and G13 control the dynamic turnover of growth factor-induced dorsal ruffles.

Growth factors induce massive actin cytoskeletal remodeling in cells. These reorganization events underlie various cellular responses such as cell migration and morphological changes. One major form of actin reorganization is the formation and disassembly of dorsal ruffles (also named waves, dorsal rings, or circular ruffles).

Organization of vesicular trafficking in epithelia.

Experiments using mammalian epithelial cell lines have elucidated biosynthetic and recycling pathways for apical and basolateral plasma-membrane proteins, and have identified components that guide apical and basolateral proteins along these pathways. These components include apical and basolateral sorting signals, adaptors for basolateral signals, and docking and fusion proteins for vesicular trafficking. Recent live-cell-imaging studies provide a real-time view of sorting processes in epithelial cells, including key roles for actin, microtubules and motors in the organization of post-Golgi trafficking.

An annexin 2 phosphorylation switch mediates p11-dependent translocation of annexin 2 to the cell surface.

Annexin 2 is a profibrinolytic co-receptor for plasminogen and tissue plasminogen activator that stimulates activation of the major fibrinolysin, plasmin, at cell surfaces. In human subjects, overexpression of annexin 2 in acute promyelocytic leukemia leads to a bleeding diathesis reflective of excessive cell surface annexin 2-dependent generation of plasmin (Menell, J. S.

The basolateral targeting signal of CD147 (EMMPRIN) consists of a single leucine and is not recognized by retinal pigment epithelium.

CD147, a type I integral membrane protein of the immunoglobulin superfamily, exhibits reversed polarity in retinal pigment epithelium (RPE). CD147 is apical in RPE in contrast to its basolateral localization in extraocular epithelia. This elicited our interest in understanding the basolateral sorting signals of CD147 in prototypic Madin-Darby canine kidney (MDCK) cells.