Myo5b

BACKGROUND: Intestinal enterocytes have an elaborate apical membrane of actin rich protrusions known as microvilli. The organization of microvilli is orchestrated by the intermicrovillar adhesion complex (IMAC) which connects the distal tips of adjacent microvilli. The IMAC is comprised of CDHR2 and CDHR5 as well as the scaffolding proteins USH1C, ANKS4B and Myosin 7b. To create an IMAC, cells must transport the proteins to the apical membrane. Myosin 5b (MYO5B) is a molecular motor that traffics ion transporters to the apical membrane of enterocytes, and we hypothesized that MYO5B may also be responsible for the localization of IMAC proteins...

Microvillus inclusion disease (MVID) is a rare, inherited, congenital, diarrheal disorder that is invariably fatal if left untreated. Within days after birth, MVID presents as a life-threatening emergency characterized by severe dehydration, metabolic acidosis, and weight loss. Diagnosis is cumbersome and can take a long time. Whether MVID could be diagnosed before birth is not known. Anecdotal reports of MVID-associated fetal bowel abnormalities suspected by ultrasonography (that is, dilated bowel loops and polyhydramnios) have been published...

Microvillus inclusion disease (MVID), a lethal congenital diarrheal disease, results from loss of function mutations in the apical actin motor myosin VB (MYO5B). How loss of MYO5B leads to both malabsorption and fluid secretion is not well understood. Serum glucocorticoid-inducible kinase 1 (SGK1) regulates intestinal carbohydrate and ion transporters including cystic fibrosis transmembrane conductance regulator (CFTR). We hypothesized that loss of SGK1 could reduce CFTR fluid secretion and MVID diarrhea. Using CRISPR-Cas9 approaches, we generated R26Cre ER;MYO5Bf/f conditional single knockout (cMYO5BKO) and R26Cre ER;MYO5Bf/f ;SGK1f/f double knockout (cSGK1/MYO5B-DKO) mice...

Bile acid transport is a complex physiologic process, of which disruption at any step can lead to progressive intrahepatic cholestasis (PFIC). The first described PFIC disorders were originally named as such before identification of a genetic cause. However, advances in clinical molecular genetics have led to the identification of additional disorders that can cause these monogenic inherited cholestasis syndromes, and they are now increasingly referred to by the affected protein causing disease. The list of PFIC disorders is expected to grow as more causative genes are discovered...

Background: Gastric cancer (GC) is still the main challenge for the social and clinical system. Increasing studies have proved that microRNA dysfunction is closely associated with the GC progression. miR-675-3p has been confirmed as the tumor support in multiple tumor cells, while its role in GC remains unclear. Methods. The clinical data in the TCGA database were excavated for analyzing the role of miR-675-3p in pan-cancer and GC. qRT-PCR was applied to detect the abundances of the genes...

Background: Biallelically mutated MYO5B is associated with microvillus inclusion disease (MVID, MIM: 251850), cholestasis, or both. This study aims at validating the splicing alteration and clinical features of an intron variant for diagnosis. Case Presentation: A homozygous variant of MYO5B , NM_001080467.2:c.2090+3A > T (NP_001073936.1:p.?) in intron 17, was identified in a patient suffering from chronic cholestasis and diarrhea. Functional validation showed that this variant caused 185 bp of intron retention in its mRNA and was predicted to present a premature translation termination site for myoVb (p...

Microvillus inclusion disease (MVID) is a congenital diarrheal disorder resulting in life-threatening secretory diarrhea in newborns. Inactivating and nonsense mutations in myosin Vb (MYO5B) have been identified in MVID patients. Work using patient tissues, cell lines, mice, and pigs has led to critical insights into the pathology of MVID and a better understanding of both apical trafficking in intestinal enterocytes and intestinal stem cell differentiation. These studies have demonstrated that loss of MYO5B or inactivating mutations lead to loss of apical sodium and water transporters, without loss of apical CFTR, accounting for the major pathology of the disease...

Structural variations (SVs) are the greatest source of variations in the genome and can lead to oncogenesis. However, the identification and interpretation of SVs in human cancer remain technologically challenging. Here, long-read sequencing is first employed to depict the signatures of structural variations in carcinogenesis of human pancreatic ductal epithelium. Then widespread reprogramming of the 3D chromatin architecture is revealed by an in situ Hi-C technique. Integrative analyses indicate that the distribution pattern of SVs among the 3D genome is highly cell-type specific and the bulk remodeling effects of SVs in the chromatin organization partly depend on intercellular genomic heterogeneity...

Pleural mesothelial cells (PMCs) play a central role in the progression of pleural fibrosis. As pleural injury progresses to fibrosis, PMCs transition to mesenchymal myofibroblast via mesothelial mesenchymal transition (MesoMT), and produce extracellular matrix (ECM) proteins including collagen and fibronectin (FN1). FN1 plays an important role in ECM maturation and facilitates ECM-myofibroblast interaction, thus facilitating fibrosis. However, the mechanism of FN1 secretion is poorly understood. We report here that myosin 5b (Myo5b) plays a critical role in the transportation and secretion of FN1 from human pleural mesothelial cells (HPMCs)...

BACKGROUND: Intestinal goblet cells secrete a protective mucus layer preventing bacteria and harmful ingested substances from contacting the columnar epithelial cells that line the intestine. Single cell RNAseq data has revealed that goblet cells have high expression of Myosin 5b (Myo5b), a molecular motor that regulates vesicle trafficking in epithelial cells. Myo5b is most widely studied in the small intestine, but it's role in the colonic epithelium and particularly goblet cells is unknown...

Microvillus Inclusion Disease (MVID) is a lethal congenital diarrheal disease resulting from loss of function mutations in the actin motor myosin VB (MYO5B) that regulates apical traffic. MVID remains without treatment to reverse the severe diarrhea that leads to death. MVID diarrhea results from both increased fluid secretion and malabsorption of ions and carbohydrates in the small intestine. Serum and Glucocorticoid-inducible kinase 1 (SGK1), is a potent regulator of ion transporters including cystic fibrosis transmembrane conductance regulator (CFTR) in the intestine...

The membrane (M) glycoprotein of coronaviruses (CoVs) serves as the nidus for virion assembly. Using a yeast two-hybrid screen, we identified the interaction of the cytosolic tail of Murine Hepatitis Virus (MHV-CoV) M protein with Myosin Vb (MYO5B) (Figure 1A). MHV-CoV M interacts specifically with the alternative splice variant of cellular MYO5B including Exon D (MYO5B+D), that also mediates interaction with cellular Rab10. When co-expressed in human lung epithelial A549 and canine kidney epithelial MDCK cells, MYO5B+D co-localized with MHV-CoV M protein, as well as with M proteins from porcine epidemic diarrhea Virus (PEDV-CoV), Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) (Figure 2)...

BACKGROUND: To overcome the constant shedding of the intestinal epithelium, the stem cells at the base of the crypt rapidly proliferate and differentiate into epithelial cells necessary for proper intestinal function. A Wnt:Notch signaling gradient exists along the crypt-villus axis, where distinct levels of Wnt relative to Notch signaling is necessary for the differentiation of epithelial cell populations. In our recent publication, mice lacking intestinal epithelial myosin 5B (MYO5B) have intracellular microvillus inclusions and cell differentiation deficits...

BACKGROUND AND AIMS: Differentiation of intestinal epithelial cells involves cell division inhibition, cell lineage choice, and brush border elaboration. Myosin Vb (MYO5B) is a motor protein that is critical for cell polarization and membrane protein trafficking in intestinal epithelial cells and its deficiency causes both hyperproliferation and microvillus defects. Recently, we reported that a bioactive phospholipid, lysophosphatidic acid (LPA), can promote cell differentiation and nutrient absorption in tamoxifen-induced MYO5B knockout mice in vivo and in enteroids...

We report a novel homozygous missense variant in ABCB4  gene in a Yemeni child born to consanguineous parents, with a significant family history of liver disease-related deaths, resulting in a progressive familial intrahepatic cholestasis (PFIC) type 3 phenotype requiring liver transplantation for intractable pruritus.

BACKGROUND & AIMS: UNC45A is a myosin (co-)chaperone, and mutations in the UNC45A gene were recently identified in osteo-oto-hepato-enteric (O2HE) syndrome patients presenting with congenital diarrhea and intrahepatic cholestasis. Congenital diarrhea and intrahepatic cholestasis are also the prime symptoms in patients with microvillus inclusion disease (MVID) and mutations in MYO5B, encoding the recycling endosome-associated myosin Vb. The aim of this study was to determine whether UNC45A and myosin Vb are functionally linked...

Congenital enteropathies (CE) are a group of rare inherited diseases with a typical onset early in life. They involve defects in enterocyte structure or differentiation. They can cause a severe condition of intestinal failure (IF). The diagnostic approach is based first on clinical presentation (consanguinity, prenatal expression, polyhydramnios, early neonatal onset, aspect of stools, persistence at bowel rest, associated extra-digestive manifestations….) and histo-pathological analyses. These rare intestinal diseases cause protracted diarrhea that might resolve, for a few, with a dietetic approach...

OBJECTIVES: Progressive Familial Intrahepatic Cholestasis, is an expanding group of autosomal recessive intrahepatic cholestatic disorders. Recently, Next Generation Sequencing allowed identifying new genes responsible for new specific disorders. Two biochemical phenotypes have been identified according to gamma-glutamyltransferase (GGT) activity. Mutations of the myosin 5B gene (MYO5B) are known to cause Microvillus Inclusion Disease. Recently, different mutations in MYO5B gene have been reported in patients with low-GGT cholestasis...

Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of disorders characterized by defects in bile secretion and presentation with intrahepatic cholestasis in infancy or childhood. The most common types include PFIC 1 (deficiency of FIC1 protein, ATP8B1 gene mutation), PFIC 2 (bile salt export pump deficiency, ABCB11 gene mutation), and PFIC 3 (multidrug resistance protein-3 deficiency, ABCB4 gene mutation). Mutational analysis of subjects with normal gamma-glutamyl transferase cholestasis of unknown etiology has led to the identification of newer variants of PFIC, known as PFIC 4, 5, and MYO5B related (sometimes known as PFIC 6)...

The genetic defect of MYO5B is usually associated with microvillus inclusion disease (MVID). MYO5B mutations are one of the rare causes of progressive familial intrahepatic cholestasis (PFIC) with normal/low gamma-glutamyl transferase (GGT). In this report, we discuss the case of a nine-month-old girl with low-GGT cholestasis whose next-generation sequencing (NGS) showed a homozygous splicing variation (c.3045+3A>T) on the MYO5B (NM_001080467) gene, which was a novel mutation. We identified that this mutation had a disease-causing effect in silico analysis...