HGNC Approved Gene Symbol: MICALL1
Cytogenetic location: 22q13.1 Genomic coordinates (GRCh38): 22:37,906,297-37,942,822 (from NCBI)
MICALL1 is a RAB (see 179508) effector that regulates endocytic recycling to the plasma membrane (Sharma et al., 2009). MICALL1 is involved in regulation of cytokinesis (Reinecke et al., 2015) and ciliogenesis (Xie et al., 2019).
Sharma et al. (2009) reported that human MICALL1 is an 863-amino acid protein with a calculated molecular mass of approximately 130 kD. MICALL1 contains an N-terminal calponin (see 600806) homology (CH) domain; a LIM domain, which consists of 2 contiguous zinc finger domains; 2 asparagine-proline-phenylalanine (NPF) motifs; and 2 C-terminal coiled-coil domains. Immunofluorescence analysis revealed that endogenous and transfected MICALL1 localized to tubular membranes in HeLa cells.
Using immunostaining analysis, Xie et al. (2019) showed that MICALL1 localized to cilia and centrosomes in both ciliated and nonciliated mouse and human cells.
Gross (2021) mapped the MICALL1 gene to chromosome 22q13.1 based on an alignment of the MICALL1 sequence (GenBank BC001090) with the genomic sequence (GRCh38).
Using pull-down, yeast 2-hybrid, and coimmunoprecipitation analyses, Sharma et al. (2009) showed that human MICALL1 interacted with EHD1 (605888) and EHD3 (605891). The interaction required the first NPF motif of MICALL1. MICALL1 and EHD1 colocalized at tubular membranes in HeLa cells and were dynamically recruited to tubular membranes with similar kinetics. However, association of MICALL1 with tubular membranes was independent of EHD1 and EHD3, as the C-terminal coiled-coli domain of MICALL1 alone was essential and sufficient for tubular localization. In contrast, MICALL1 was required for association of EHD1 with tubular membranes. MICALL1 recruited and linked EHD1 and RAB8A (165040) on membrane tubules, thereby regulating endocytic recycling from the endocytic recycling compartment (ERC) to the plasma membrane.
Using immunoprecipitation analysis in HeLa cells, Giridharan et al. (2013) demonstrated that the SH3 domain of SYND2 (SDC2; 142460) interacted directly with 2 of the 14 proline-rich domains (PRDs) of MICALL1. SYND2 colocalized with MICALL1 and EHD1 at tubular recycling endosomes (REs), with SYND2 and MICALL1 displaying similar dynamics of association with tubular membranes. Knockdown analysis showed that interaction between MICALL1 and SYND2 was required for their localization to tubular REs, whereas EHD1 stabilized interaction between MICALL1 and SYND2 on recycling tubules. A lipid overlay assay revealed that MICALL1 and SYND2 bound to phosphatidic acid in membranes of REs for localization and for RE tubule biogenesis. Further analysis demonstrated that MICALL and SYND2 were capable of generating tubules from phosphatidic acid-containing membranes.
Using yeast 2-hybrid screening, pull-down assays, and immunofluorescence analysis in transfected Madin-Darby canine kidney (MDCK) cells, Zahraoui (2014) showed that human MICALL1 interacted and colocalized with RAB13 (602672), but that MICALL1 did not function as a GTPase-activating protein for RAB13. MICALL1 was associated with late and recycling endosomes in transfected MDCK cells, with rapid movement in cytoplasm. Knockdown of endogenous Micall1 in MDCK cells did not alter distribution of tight junction proteins, but it affected trafficking of epidermal growth factor receptor (EGFR; 131550). Overexpression of human MICALL1 led to accumulation of Egfr in late endosomal compartments. In contrast, Micall1 knockdown resulted in distribution of internalized Egfr in vesicles spread throughout the cytoplasm and promoted Egfr degradation. The author concluded that MICALL1 is involved in sorting/targeting EGFR to the recycling pathway.
Using immunofluorescence analysis, Reinecke et al. (2014) showed that MICALL1 colocalized with SRC (190090) along tubular membranes that radiated from the ERC in HeLa cells under steady-state conditions. MICALL1 interacted with SRC and was required for SRC activation and transport from perinuclear region to the plasma membrane upon epidermal growth factor (EGF; 131530) stimulation. Likewise, MICALL1 colocalized with SRC in human foreskin fibroblasts and was required for SRC recruitment to circular dorsal ruffles (CDRs) following platelet-derived growth factor (PDGF; see 173430) stimulation. MICALL1 was also required for PDGF-induced focal adhesion turnover. The results indicated that MICALL1 regulates transport of active SRC to focal adhesions, thereby controlling turnover of focal adhesions. Further analysis revealed that MICALL1 regulated cell spreading and was required for migration of human foreskin fibroblasts. Knockdown analysis in HeLa cells demonstrated that EHD1 was required for SRC transport and activation and acted as a molecular 'pinchase' on MICALL1 tubules to release SRC from the ERC in response to EGF. Inactivated SRC was maintained at the ERC. Upon EGF stimulation, SRC was sorted into MICALL1-decorated tubular recycling endosomes and became partially activated. EHD1 was recruited to tubular REs by MICALL1, where it vesiculated recycling endosomes that contained SRC and were transported to the plasma membrane, where SRC became fully activated to mediate rearrangement of the actin cytoskeletal CDRs, focal adhesion disassembly, and cell migration.
Reinecke et al. (2015) found that MICALL1 and EHD1 were involved in regulation of cell cycle, as depletion of MICALL1 or EHD1 in HeLa cells caused cell cycle defects. MICALL1 and EHD1 were required for cytokinesis and transport of REs to the intercellular bridge (ICB). MICALL1 localized to the distal ICB during late cytokinesis and recruited EHD1 to the ICB, which facilitated release of REs from the base of the ICB. Knockdown analysis showed that localization of MICALL1 to the ICB was independent of EHD1, RAB11 (605570), and RAB35 (604199). Moreover, only depletion of EHD1, and not depletion of MICALL1, RAB11, or RAB35, affected central spindle formation. MICALL1 and EHD1 differentially influenced microtubule dynamics during early and late mitosis, as EHD1 and RAB35 regulated mitotic spindle orientation, whereas MICALL1 controlled spindle length, thereby affecting regulation of kinetochores, inter-kinetochore tension, and kinetochore fibers.
Using knockdown analysis, Xie et al. (2019) showed that MICALL1 and EHD1 regulated ciliogenesis, as depletion of MICALL1 impaired ciliogenesis in a similar manner to EHD1 knockdown in RPE-1 cells and prevented CP110 (609544) removal from the mother centriole. EHD1 was recruited to the primary cilium by MICALL1, prior to EHD1 functioning in regulation of ciliogenesis. Immunoprecipitation analysis with NIH3T3 cells revealed that Micall1 was initially anchored to centrosomes in nonciliated cells through direct interaction with gamma-tubulin (see 191135) and/or alpha-tubulin (see 602529)/beta-tubulin (see 191130) heterodimers.
Giridharan, S. S. P., Cai, B., Vitale, N., Naslavsky, N., Caplan, S. Cooperation of MICAL-L1, syndapin2, and phosphatidic acid in tubular recycling endosome biogenesis. Molec. Biol. Cell 24: 1776-1790, 2013. [PubMed: 23596323] [Full Text: https://doi.org/10.1091/mbc.E13-01-0026]
Gross, M. B. Personal Communication. Baltimore, Md. 10/8/2021.
Reinecke, J. B., Katafiasz, D., Naslavsky, N., Caplan, S. Regulation of Src trafficking and activation by the endocytic regulatory proteins MICAL-L1 and EHD1. J. Cell Sci. 127: 1684-1698, 2014. [PubMed: 24481818] [Full Text: https://doi.org/10.1242/jcs.133892]
Reinecke, J. B., Katafiasz, D., Naslavsky, N., Caplan, S. Novel functions for the endocytic regulatory proteins MICAL-L1 and EHD1 in mitosis. Traffic 16: 48-67, 2015. [PubMed: 25287187] [Full Text: https://doi.org/10.1111/tra.12234]
Sharma, M., Giridharan, S. S. P., Rahajeng, J., Naslavsky, N., Caplan, S. MICAL-L1 links EHD1 to tubular recycling endosomes and regulates receptor recycling. Molec. Biol. Cell 20: 5181-5194, 2009. [PubMed: 19864458] [Full Text: https://doi.org/10.1091/mbc.e09-06-0535]
Xie, S., Farmer, T., Naslavsky, N., Caplan, S. MICAL-L1 coordinates ciliogenesis by recruiting EHD1 to the primary cilium. J. Cell Sci. 132: jsc233973, 2019. [PubMed: 31615969] [Full Text: https://doi.org/10.1242/jcs.233973]
Zahraoui, A. MICAL-like1 in endosomal signaling. Methods Enzymol. 535: 419-437, 2014. [PubMed: 24377937] [Full Text: https://doi.org/10.1016/B978-0-12-397925-4.00024-9]