All Publications

  • CD63 is Regulated by Iron via the IRE-IRP System and is Important for Ferritin Secretion by Extracellular Vesicles. Blood Yanatori, I., Richardson, D. R., Dhekne, H. S., Toyokuni, S., Kishi, F. 2021


    Extracellular vesicles (EVs) transfer functional molecules between cells. CD63 is a widely recognized EV marker that contributes to EV secretion from cells. However, the regulation of its expression remains largely unknown. Ferritin is a cellular iron storage protein that can be also secreted by the exosome pathway (Truman-Rosentsvit M. et al. BLOOD 131 (2018) 342-352), with serum ferritin levels classically reflecting body iron stores. Iron metabolism-associated proteins, such as ferritin, are intricately regulated by cellular iron levels via the iron responsive element (IRE)-iron regulatory protein (IRP) system. Herein, we present a novel mechanism demonstrating that the expression of the EV-associated protein, CD63, is under the regulation of the IRE-IRP system. We discovered a canonical IRE in the 5'-untranslated region (UTR) of CD63 mRNA responsible for regulating its expression in response to increased iron. Cellular iron-loading caused a marked increase in CD63 expression and the secretion from cells of CD63 positive (i.e., CD63(+)) EVs, which were shown to contain ferritin-H (FtH) and -L (FtL). Our results demonstrate that under iron-loading, intracellular ferritin is transferred via nuclear receptor coactivator 4 (NCOA4) to CD63(+) EVs that are then secreted. Such iron-regulated secretion of the major iron storage protein ferritin via CD63(+) EVs, poses significant impact for understanding the local cell-to-cell exchange of ferritin and iron.

    View details for DOI 10.1182/blood.2021010995

    View details for PubMedID 34265052

  • Pathogenic LRRK2 regulates ciliation probability upstream of tau tubulin kinase 2 via Rab10 and RILPL1 proteins. Proceedings of the National Academy of Sciences of the United States of America Sobu, Y., Wawro, P. S., Dhekne, H. S., Yeshaw, W. M., Pfeffer, S. R. 2021; 118 (10)


    Mutations that activate LRRK2 protein kinase cause Parkinson's disease. We showed previously that Rab10 phosphorylation by LRRK2 enhances its binding to RILPL1, and together, these proteins block cilia formation in a variety of cell types, including patient derived iPS cells. We have used live-cell fluorescence microscopy to identify, more precisely, the effect of LRRK2 kinase activity on both the formation of cilia triggered by serum starvation and the loss of cilia seen upon serum readdition. LRRK2 activity decreases the overall probability of ciliation without changing the rates of cilia formation in R1441C LRRK2 MEF cells. Cilia loss in these cells is accompanied by ciliary decapitation, and kinase activity does not change the timing or frequency of decapitation or the rate of cilia loss but increases the percent of cilia that are lost upon serum addition. LRRK2 activity, or overexpression of RILPL1 protein, blocks release of CP110 from the mother centriole, a step normally required for early ciliogenesis; LRRK2 blockade of CP110 uncapping requires Rab10 and RILPL1 proteins and is due to failure to recruit TTBK2, a kinase needed for CP110 release. In contrast, deciliation probability does not change in cells lacking Rab10 or RILPL1 and relies on a distinct LRRK2 pathway. These experiments provide critical detail to our understanding of the cellular consequences of pathogenic LRRK2 mutation and indicate that LRRK2 blocks ciliogenesis upstream of TTBK2 and enhances the deciliation process in response to serum addition.

    View details for DOI 10.1073/pnas.2005894118

    View details for PubMedID 33653948

  • LRRK2-phosphorylated Rab10 sequesters Myosin Va with RILPL2 during ciliogenesis blockade. Life science alliance Dhekne, H. S., Yanatori, I., Vides, E. G., Sobu, Y., Diez, F., Tonelli, F., Pfeffer, S. R. 2021; 4 (5)


    Activating mutations in LRRK2 kinase causes Parkinson's disease. Pathogenic LRRK2 phosphorylates a subset of Rab GTPases and blocks ciliogenesis. Thus, defining novel phospho-Rab interacting partners is critical to our understanding of the molecular basis of LRRK2 pathogenesis. RILPL2 binds with strong preference to LRRK2-phosphorylated Rab8A and Rab10. RILPL2 is a binding partner of the motor protein and Rab effector, Myosin Va. We show here that the globular tail domain of Myosin Va also contains a high affinity binding site for LRRK2-phosphorylated Rab10. In the presence of pathogenic LRRK2, RILPL2 and MyoVa relocalize to the peri-centriolar region in a phosphoRab10-dependent manner. PhosphoRab10 retains Myosin Va over pericentriolar membranes as determined by fluorescence loss in photobleaching microscopy. Without pathogenic LRRK2, RILPL2 is not essential for ciliogenesis but RILPL2 over-expression blocks ciliogenesis in RPE cells independent of tau tubulin kinase recruitment to the mother centriole. These experiments show that LRRK2 generated-phosphoRab10 dramatically redistributes a significant fraction of Myosin Va and RILPL2 to the mother centriole in a manner that likely interferes with Myosin Va's role in ciliogenesis.

    View details for DOI 10.26508/lsa.202101050

    View details for PubMedID 33727250

  • A pathway for Parkinson's Disease LRRK2 kinase to block primary cilia and Sonic hedgehog signaling in the brain. eLife Dhekne, H. S., Yanatori, I., Gomez, R. C., Tonelli, F., Diez, F., Schule, B., Steger, M., Alessi, D. R., Pfeffer, S. R. 2018; 7


    Parkinson's disease-associated LRRK2 kinase phosphorylates multiple Rab GTPases, including Rab8A and Rab10. We show here that LRRK2 kinase interferes with primary cilia formation in cultured cells, human LRRK2 G2019S iPS cells and in the cortex of LRRK2 R1441C mice. Rab10 phosphorylation strengthens its intrinsic ability to block ciliogenesis by enhancing binding to RILPL1. Importantly, the ability of LRRK2 to interfere with ciliogenesis requires both Rab10 and RILPL1 proteins. Pathogenic LRRK2 influences the ability of cells to respond to cilia-dependent, Hedgehog signaling as monitored by Gli1 transcriptional activation. Moreover, cholinergic neurons in the striatum of LRRK2 R1441C mice show decreased ciliation, which will decrease their ability to sense Sonic hedgehog in a neuro-protective circuit that supports dopaminergic neurons. These data reveal a molecular pathway for regulating cilia function that likely contributes to Parkinson's disease-specific pathology.Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

    View details for PubMedID 30398148

  • MYO5B, STX3, and STXBP2 mutations reveal a common disease mechanism that unifies a subset of congenital diarrheal disorders: A mutation update HUMAN MUTATION Dhekne, H. S., Pylypenko, O., Overeem, A. W., Ferreira, R. J., van der Velde, K., Rings, E. M., Posovszky, C., Swertz, M. A., Houdusse, A., van IJzendoorn, S. D. 2018; 39 (3): 333–44


    Microvillus inclusion disease (MVID) is a rare but fatal autosomal recessive congenital diarrheal disorder caused by MYO5B mutations. In 2013, we launched an open-access registry for MVID patients and their MYO5B mutations ( Since then, additional unique MYO5B mutations have been identified in MVID patients, but also in non-MVID patients. Animal models have been generated that formally prove the causality between MYO5B and MVID. Importantly, mutations in two other genes, STXBP2 and STX3, have since been associated with variants of MVID, shedding new light on the pathogenesis of this congenital diarrheal disorder. Here, we review these additional genes and their mutations. Furthermore, we discuss recent data from cell studies that indicate that the three genes are functionally linked and, therefore, may constitute a common disease mechanism that unifies a subset of phenotypically linked congenital diarrheal disorders. We present new data based on patient material to support this. To congregate existing and future information on MVID geno-/phenotypes, we have updated and expanded the MVID registry to include all currently known MVID-associated gene mutations, their demonstrated or predicted functional consequences, and associated clinical information.

    View details for DOI 10.1002/humu.23386

    View details for Web of Science ID 000424807600002

    View details for PubMedID 29266534

    View details for PubMedCentralID PMC5838515

  • Rab29 activation of the Parkinson's disease-associated LRRK2 kinase EMBO JOURNAL Purlyte, E., Dhekne, H. S., Sarhan, A. R., Gomez, R., Lis, P., Wightman, M., Martinez, T. N., Tonelli, F., Pfeffer, S. R., Alessi, D. R. 2018; 37 (1): 1–18


    Parkinson's disease predisposing LRRK2 kinase phosphorylates a group of Rab GTPase proteins including Rab29, within the effector-binding switch II motif. Previous work indicated that Rab29, located within the PARK16 locus mutated in Parkinson's patients, operates in a common pathway with LRRK2. Here, we show that Rab29 recruits LRRK2 to the trans-Golgi network and greatly stimulates its kinase activity. Pathogenic LRRK2 R1441G/C and Y1699C mutants that promote GTP binding are more readily recruited to the Golgi and activated by Rab29 than wild-type LRRK2. We identify conserved residues within the LRRK2 ankyrin domain that are required for Rab29-mediated Golgi recruitment and kinase activation. Consistent with these findings, knockout of Rab29 in A549 cells reduces endogenous LRRK2-mediated phosphorylation of Rab10. We show that mutations that prevent LRRK2 from interacting with either Rab29 or GTP strikingly inhibit phosphorylation of a cluster of highly studied biomarker phosphorylation sites (Ser910, Ser935, Ser955 and Ser973). Our data reveal that Rab29 is a master regulator of LRRK2, controlling its activation, localization, and potentially biomarker phosphorylation.

    View details for PubMedID 29212815

    View details for PubMedCentralID PMC5753036

  • Systematic proteomic analysis of LRRK2-mediated Rab GTPase phosphorylation establishes a connection to ciliogenesis ELIFE Steger, M., Diez, F., Dhekne, H. S., Lis, P., Nirujogi, R. S., Karayel, O., Tonelli, F., Martinez, T. N., Lorentzen, E., Pfeffer, S. R., Alessi, D. R., Mann, M. 2017; 6


    We previously reported that Parkinson's disease (PD) kinase LRRK2 phosphorylates a subset of Rab GTPases on a conserved residue in their switch-II domains (Steger et al., 2016) (PMID: 26824392). Here, we systematically analyzed the Rab protein family and found 14 of them (Rab3A/B/C/D, Rab5A/B/C, Rab8A/B, Rab10, Rab12, Rab29, Rab35 and Rab43) to be specifically phosphorylated by LRRK2, with evidence for endogenous phosphorylation for ten of them (Rab3A/B/C/D, Rab8A/B, Rab10, Rab12, Rab35 and Rab43). Affinity enrichment mass spectrometry revealed that the primary ciliogenesis regulator, RILPL1 specifically interacts with the LRRK2-phosphorylated forms of Rab8A and Rab10, whereas RILPL2 binds to phosphorylated Rab8A, Rab10, and Rab12. Induction of primary cilia formation by serum starvation led to a two-fold reduction in ciliogenesis in fibroblasts derived from pathogenic LRRK2-R1441G knock-in mice. These results implicate LRRK2 in primary ciliogenesis and suggest that Rab-mediated protein transport and/or signaling defects at cilia may contribute to LRRK2-dependent pathologies.

    View details for PubMedID 29125462

  • Myosin Vb and Rab11a regulate phosphorylation of ezrin in enterocytes JOURNAL OF CELL SCIENCE Dhekne, H. S., Hsiao, N., Roelofs, P., Kumari, M., Slim, C. L., Rings, E. H., van IJzendoorn, S. C. 2014; 127 (5): 1007-1017


    Microvilli at the apical surface of enterocytes allow the efficient absorption of nutrients in the intestine. Ezrin activation by its phosphorylation at T567 is important for microvilli development, but how such ezrin phosphorylation is controlled is not well understood. We demonstrate that a subset of kinases that phosphorylate ezrin closely co-distributes with apical recycling endosome marker Rab11a in the subapical domain. Expression of dominant-negative Rab11a mutant or depletion of the Rab11a-binding motor protein myosin Vb prevents the subapical enrichment of Rab11a and these kinases and inhibits ezrin phosphorylation and microvilli development, without affecting the polarized distribution of ezrin itself. We observe a similar loss of the subapical enrichment of Rab11a and the kinases and reduced phosphorylation of ezrin in microvillus inclusion disease, which is associated with MYO5B mutations, intestinal microvilli atrophy and malabsorption. Thus, part of the machinery for ezrin activation depends on recycling endosomes controlled by myosin Vb and Rab11a which, we propose, might act as subapical signaling platforms that enterocytes use to regulate development of microvilli and maintain human intestinal function.

    View details for DOI 10.1242/jcs.137273

    View details for Web of Science ID 000332116300009

    View details for PubMedID 24413175

  • An Overview and Online Registry of Microvillus Inclusion Disease Patients and their MYO5B Mutations HUMAN MUTATION van der Velde, K. J., Dhekne, H. S., Swertz, M. A., Sirigu, S., Ropars, V., Vinke, P. C., Rengaw, T., van den Akker, P. C., Rings, E. H., Houdusse, A., van IJzendoorn, S. C. 2013; 34 (12): 1597-1605


    Microvillus inclusion disease (MVID) is one of the most severe congenital intestinal disorders and is characterized by neonatal secretory diarrhea and the inability to absorb nutrients from the intestinal lumen. MVID is associated with patient-, family-, and ancestry-unique mutations in the MYO5B gene, encoding the actin-based motor protein myosin Vb. Here, we review the MYO5B gene and all currently known MYO5B mutations and for the first time methodologically categorize these with regard to functional protein domains and recurrence in MYO7A associated with Usher syndrome and other myosins. We also review animal models for MVID and the latest data on functional studies related to the myosin Vb protein. To congregate existing and future information on MVID geno-/phenotypes and facilitate its quick and easy sharing among clinicians and researchers, we have constructed an online MOLGENIS-based international patient registry ( This easily accessible database currently contains detailed information of 137 MVID patients together with reported clinical/phenotypic details and 41 unique MYO5B mutations, of which several unpublished. The future expansion and prospective nature of this registry is expected to improve disease diagnosis, prognosis, and genetic counseling.

    View details for DOI 10.1002/humu.22440

    View details for Web of Science ID 000326864200002

    View details for PubMedID 24014347