R01DK129473

Role of AJC in Umbrella Cell Function and Dysfunction - Abstract

A critical component of the umbrella cell barrier is the apical junctional complex (AJC), a multipartite, belt-like structure comprised of the tight junction, the adherens junction, desmosomes, and an associated cytoskeleton. Functions of the AJC include regulation of paracellular flux, cell-cell adhesion, and mechanotransduction. Despite evidence that the umbrella cell AJC is integral to urothelial function and disrupted in several lower urinary tract disorders, we have limited understanding of key aspects of umbrella cell AJC biology and pathobiology including:

(I) How the AJC maintains its continuity in the face of cyclical bladder filling and voiding;
(II) How the AJC is organized to undergo these transitions and the function of the cytoskeleton in these events; and
(III) How the umbrella cell AJC senses tension and whether pathologically high intravesical pressures stimulate AJC-associated mechanotransduction pathways.

Our preliminary studies include the novel findings that during bladder filling, the AJC perimeter expands dramatically, a process that depends on changes in the actin cytoskeleton and vesicular traffic, likely directed toward the AJC. In contrast, the AJC contracts soon after bladder voiding, events driven by the non-muscle myosin II-triggered contraction of the actin cytoskeleton, RHOA, as well as endocytosis.

Based on available data, we hypothesize that critical functions of the umbrella cell AJC are to maintain urothelial barrier function by undergoing dynamic expansion and contraction and to serve as a site of mechanotransduction under normal and pathological conditions.

To test this global hypothesis, we propose the following experiments:

Aim 1: We will use a newly developed biaxial stretching device, coupled with live-cell image analysis, to determine if increased strain triggers exocytosis of junction-associated proteins directed toward the AJC, and if release of strain stimulates their endocytosis. We will also assess if blocking AJC expansion perturbs urothelial barrier function.

Aim 2: We will focus on deciphering the function and organization of the umbrella cell AJC-associated cytoskeleton. We will use super-resolution confocal imaging, as well as electron microscopy to reconstruct the umbrella cell AJC in 3D. In addition, we will determine if formins drive actin polymerization in response to filling.

Aim 3: We will use tension sensors to determine if transmembrane proteins associated with the umbrella cell AJC sense force, and assess whether junction-associated signaling pathways are activated in response to partial bladder outlet obstruction (PBOO).

Upon completion of these studies, we will have new insights into how umbrella cell AJC dynamics contribute to urothelial barrier function, the organization of the AJC and the function of its associated cytoskeleton, and important new information about how the AJC senses and responds to perturbations in its mechanical milieu, including in response to PBOO.

University Of Pittsburgh - Of The Commonwealth System Of Higher Education

(1) TO PROMOTE EXTRAMURAL BASIC AND CLINICAL BIOMEDICAL RESEARCH THAT IMPROVES THE UNDERSTANDING OF THE MECHANISMS UNDERLYING DISEASE AND LEADS TO IMPROVED PREVENTIONS, DIAGNOSIS, AND TREATMENT OF DIABETES, DIGESTIVE, AND KIDNEY DISEASES. PROGRAMMATIC AREAS WITHIN THE NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES INCLUDE DIABETES, DIGESTIVE, ENDOCRINE, HEMATOLOGIC, LIVER, METABOLIC, NEPHROLOGIC, NUTRITION, OBESITY, AND UROLOGIC DISEASES. SPECIFIC PROGRAMS AREAS OF INTEREST INCLUDE THE FOLLOWING: (A) FOR DIABETES, ENDOCRINE, AND METABOLIC DISEASES AREAS: FUNDAMENTAL AND CLINICAL STUDIES INCLUDING THE ETIOLOGY, PATHOGENESIS, PREVENTION, DIAGNOSIS, TREATMENT AND CURE OF DIABETES MELLITUS AND ITS COMPLICATIONS; NORMAL AND ABNORMAL FUNCTION OF THE PITUITARY, THYROID, PARATHYROID, ADRENAL, AND OTHER HORMONE SECRETING GLANDS; HORMONAL REGULATION OF BONE, ADIPOSE TISSUE, AND LIVER; ON FUNDAMENTAL ASPECTS OF SIGNAL TRANSDUCTION, INCLUDING THE ACTION OF HORMONES, COREGULATORS, AND CHROMATIN REMODELING PROTEINS; HORMONE BIOSYNTHESIS, SECRETION, METABOLISM, AND BINDING; AND ON HORMONAL REGULATION OF GENE EXPRESSION AND THE ROLE(S) OF SELECTIVE RECEPTOR MODULATORS AS PARTIAL AGONISTS OR ANTAGONISTS OF HORMONE ACTION; AND FUNDAMENTAL STUDIES RELEVANT TO METABOLIC DISORDERS INCLUDING MEMBRANE STRUCTURE, FUNCTION, AND TRANSPORT PHENOMENA AND ENZYME BIOSYNTHESIS; AND BASIC AND CLINICAL STUDIES ON THE ETIOLOGY, PATHOGENESIS, PREVENTION, AND TREATMENT OF INHERITED METABOLIC DISORDERS (SUCH AS CYSTIC FIBROSIS). (B) FOR DIGESTIVE DISEASE AND NUTRITION AREAS: GENETICS AND GENOMICS OF THE GI TRACT AND ITS DISEASES; GENETICS AND GENOMICS OF LIVER/PANCREAS AND DISEASES; GENETICS AND GENOMICS OF NUTRITION; GENETICS AND GENOMICS OF OBESITY; BARIATRIC SURGERY; CLINICAL NUTRITION RESEARCH; CLINICAL OBESITY RESEARCH; COMPLICATIONS OF CHRONIC LIVER DISEASE; FATTY LIVER DISEASE; GENETIC LIVER DISEASE; HIV AND LIVER; CELL INJURY, REPAIR, FIBROSIS AND INFLAMMATION IN THE LIVER; LIVER CANCER; LIVER TRANSPLANTATION; PEDIATRIC LIVER DISEASE; VIRAL HEPATITIS AND INFECTIOUS DISEASES; GASTROINTESTINAL AND NUTRITION EFFECTS OF AIDS; GASTROINTESTINAL MUCOSAL AND IMMUNOLOGY; GASTROINTESTINAL MOTILITY; BASIC NEUROGASTROENTEROLOGY; GASTROINTESTINAL DEVELOPMENT; GASTROINTESTINAL EPITHELIAL BIOLOGY; GASTROINTESTINAL INFLAMMATION; DIGESTIVE DISEASES EPIDEMIOLOGY AND DATA SYSTEMS; NUTRITIONAL EPIDEMIOLOGY AND DATA SYSTEMS; AUTOIMMUNE LIVER DISEASE; BILE, BILIRUBIN AND CHOLESTASIS; BIOENGINEERING AND BIOTECHNOLOGY RELATED TO DIGESTIVE DISEASES, LIVER, NUTRITION AND OBESITY; CELL AND MOLECULAR BIOLOGY OF THE LIVER; DEVELOPMENTAL BIOLOGY AND REGENERATION; DRUG-INDUCED LIVER DISEASE; GALLBLADDER DISEASE AND BILIARY DISEASES; EXOCRINE PANCREAS BIOLOGY AND DISEASES; GASTROINTESTINAL NEUROENDOCRINOLOGY; GASTROINTESTINAL TRANSPORT AND ABSORPTION; NUTRIENT METABOLISM; PEDIATRIC CLINICAL OBESITY; CLINICAL TRIALS IN DIGESTIVE DISEASES; LIVER CLINICAL TRIALS; OBESITY PREVENTION AND TREATMENT; AND OBESITY AND EATING DISORDERS. (C) FOR KIDNEY, UROLOGIC AND HEMATOLOGIC DISEASES AREAS: STUDIES OF THE DEVELOPMENT, PHYSIOLOGY, AND CELL BIOLOGY OF THE KIDNEY; PATHOPHYSIOLOGY OF THE KIDNEY; GENETICS OF KIDNEY DISORDERS; IMMUNE MECHANISMS OF KIDNEY DISEASE; KIDNEY DISEASE AS A COMPLICATION OF DIABETES; EFFECTS OF DRUGS, NEPHROTOXINS AND ENVIRONMENTAL TOXINS ON THE KIDNEY; MECHANISMS OF KIDNEY INJURY REPAIR; IMPROVED DIAGNOSIS, PREVENTION AND TREATMENT OF CHRONIC KIDNEY DISEASE AND END-STAGE RENAL DISEASE; IMPROVED APPROACHES TO MAINTENANCE DIALYSIS THERAPIES; BASIC STUDIES OF LOWER URINARY TRACT CELL BIOLOGY, DEVELOPMENT, PHYSIOLOGY, AND PATHOPHYSIOLOGY; CLINICAL STUDIES OF BLADDER DYSFUNCTION, INCONTINENCE, PYELONEPHRITIS, INTERSTITIAL CYSTITIS, BENIGN PROSTATIC HYPERPLASIA, UROLITHIASIS, AND VESICOURETERAL REFLUX; DEVELOPMENT OF NOVEL DIAGNOSTIC TOOLS AND IMPROVED THERAPIES, INCLUDING TISSUE ENGINEERING STRATEGIES, FOR UROLOGIC DISORDERS;RESEARCH ON HEMATOPOIETIC CELL DIFFERENTIATION; METABOLISM OF IRON OVERLOAD AND DEFICIENCY; STRUCTURE, BIOSYNTHESIS AND GENETIC REGULATION OF HEMOGLOBIN; AS WELL AS RESEARCH ON THE ETIOLOGY, PATHOGENESIS, AND THERAPEUTIC MODALITIES FOR THE ANEMIA OF INFLAMMATION AND CHRONIC DISEASES.(2) TO ENCOURAGE BASIC AND CLINICAL RESEARCH TRAINING AND CAREER DEVELOPMENT OF SCIENTISTS DURING THE EARLY STAGES OF THEIR CAREERS. THE RUTH L. KIRSCHSTEIN NATIONAL RESEARCH SERVICE AWARD (NRSA) FUNDS BASIC AND CLINICAL RESEARCH TRAINING, SUPPORT FOR CAREER DEVELOPMENT, AND THE TRANSITION FROM POSTDOCTORAL BIOMEDICAL RESEARCH TRAINING TO INDEPENDENT RESEARCH RELATED TO DIABETES, DIGESTIVE, ENDOCRINE, HEMATOLOGIC, LIVER, METABOLIC, NEPHROLOGIC, NUTRITION, OBESITY, AND UROLOGIC DISEASES. (3) TO EXPAND AND IMPROVE THE SMALL BUSINESS INNOVATION RESEARCH (SBIR) PROGRAM. THE SBIR PROGRAM AIMS TO INCREASE AND FACILITATE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT; TO ENHANCE SMALL BUSINESS PARTICIPATION IN FEDERAL RESEARCH AND DEVELOPMENT; AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION. (4) TO UTILIZE THE SMALL BUSINESS TECHNOLOGY TRANSFER (STTR) PROGRAM. THE STTR PROGRAM INTENDS TO STIMULATE AND FOSTER SCIENTIFIC AND TECHNOLOGICAL INNOVATION THROUGH COOPERATIVE RESEARCH AND DEVELOPMENT CARRIED OUT BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS; TO FOSTER TECHNOLOGY TRANSFER BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS; TO INCREASE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT; AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION.

93.847 - Diabetes, Digestive, and Kidney Diseases Extramural Research

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) [HHS - NIH]

Pittsburgh, Pennsylvania 152133203 United States

Single Zip Code

NIH Research Project Grant (Parent R01 Clinical Trial Not Allowed) (PA-20-185)

Amendment Since initial award the End Date has been extended from 06/30/26 to 06/30/27 and the total obligations have increased 381% from $660,849 to $3,179,860.