Jaroslava Halper

Bio: Jaroslava Halper is an academic researcher from University of Georgia. The author has contributed to research in topics: Transforming growth factor & Growth factor. The author has an hindex of 21, co-authored 59 publications receiving 2476 citations.

Progranulin is a mediator of the wound response.

Abstract: Annually, 1.25 million individuals suffer burns in the United States and 6.5 million experience chronic skin ulcers, often from diabetes, pressure or venous stasis1. Growth factors are essential mediators of wound repair1,2, but their success as therapeutics in wound treatment has, so far, been limited1,2. Therefore, there is a need to identify new wound-response regulatory factors, but few have appeared in recent years1,2. Progranulin3 (also called granulin or epithelin precursor4, acrogranin5 or PC-derived growth factor6) is a growth factor involved in tumorigenesis6,7,8,9,10,11 and development12,13. Peptides derived from progranulin have been isolated from inflammatory cells14, which led to suggestions that progranulin gene products are involved in the wound response10,14, but this remains undemonstrated. We report that in murine transcutaneous puncture wounds, progranulin mRNA is expressed in the inflammatory infiltrate and is highly induced in dermal fibroblasts and endothelia following injury. When applied to a cutaneous wound, progranulin increased the accumulation of neutrophils, macrophages, blood vessels and fibroblasts in the wound. It acts directly on isolated dermal fibroblasts and endothelial cells to promote division, migration and the formation of capillary-like tubule structures. Progranulin is, therefore, a probable wound-related growth factor.

Basic Components of Connective Tissues and Extracellular Matrix: Elastin, Fibrillin, Fibulins, Fibrinogen, Fibronectin, Laminin, Tenascins and Thrombospondins

Abstract: Collagens are the most abundant components of the extracellular matrix and many types of soft tissues. Elastin is another major component of certain soft tissues, such as arterial walls and ligaments. Many other molecules, though lower in quantity, function as essential components of the extracellular matrix in soft tissues. Some of these are reviewed in this chapter. Besides their basic structure, biochemistry and physiology, their roles in disorders of soft tissues are discussed only briefly as most chapters in this volume deal with relevant individual compounds. Fibronectin with its muldomain structure plays a role of “master organizer” in matrix assembly as it forms a bridge between cell surface receptors, e.g., integrins, and compounds such collagen, proteoglycans and other focal adhesion molecules. It also plays an essential role in the assembly of fibrillin-1 into a structured network. Laminins contribute to the structure of the extracellular matrix (ECM) and modulate cellular functions such as adhesion, differentiation, migration, stability of phenotype, and resistance towards apoptosis. Though the primary role of fibrinogen is in clot formation, after conversion to fibrin by thrombin, it also binds to a variety of compounds, particularly to various growth factors, and as such fibrinogen is a player in cardiovascular and extracellular matrix physiology. Elastin, an insoluble polymer of the monomeric soluble precursor tropoelastin, is the main component of elastic fibers in matrix tissue where it provides elastic recoil and resilience to a variety of connective tissues, e.g., aorta and ligaments. Elastic fibers regulate activity of TGFβs through their association with fibrillin microfibrils. Elastin also plays a role in cell adhesion, cell migration, and has the ability to participate in cell signaling. Mutations in the elastin gene lead to cutis laxa. Fibrillins represent the predominant core of the microfibrils in elastic as well as non-elastic extracellular matrixes, and interact closely with tropoelastin and integrins. Not only do microfibrils provide structural integrity of specific organ systems, but they also provide a scaffold for elastogenesis in elastic tissues. Fibrillin is important for the assembly of elastin into elastic fibers. Mutations in the fibrillin-1 gene are closely associated with Marfan syndrome. Fibulins are tightly connected with basement membranes, elastic fibers and other components of extracellular matrix and participate in formation of elastic fibers. Tenascins are ECM polymorphic glycoproteins found in many connective tissues in the body. Their expression is regulated by mechanical stress both during development and in adulthood. Tenascins mediate both inflammatory and fibrotic processes to enable effective tissue repair and play roles in pathogenesis of Ehlers-Danlos, heart disease, and regeneration and recovery of musculo-tendinous tissue. One of the roles of thrombospondin 1 is activation of TGFβ. Increased expression of thrombospondin and TGFβ activity was observed in fibrotic skin disorders such as keloids and scleroderma. Cartilage oligomeric matrix protein (COMP) or thrombospondin-5 is primarily present in the cartilage. High levels of COMP are present in fibrotic scars and systemic sclerosis of the skin, and in tendon, especially with physical activity, loading and post-injury. It plays a role in vascular wall remodeling and has been found in atherosclerotic plaques as well.

Cellular Localization of Gene Expression for Progranulin

Abstract: Granulins, also called epithelins, are 6-kD peptides with growth modulatory effects on a variety of cells. The granulin/epithelin precursor supports tumorigenesis in appropriate cell models and is the only growth factor able to overcome the cell cycle block that occurs in murine fibroblasts after deletion of a functional IGF-1 receptor. However, little is known of the role of granulin/epithelin gene products in vivo. To understand the physiological role of granulins it is essential to know the cell types and conditions in which it is expressed. We examined granulin/epithelin gene expression in adult rodents by in situ hybridization. The granulin/epithelin precursor is constitutively expressed in a number of epithelia, particularly in the skin, GI tract, and reproductive system. Other epithelia express the gene less strongly. Progranulin is expressed in immune cells in vivo and in specific neurons in the brain, including Purkinje cells, pyramidal cells of the hippocampus, and some cerebral cortical neurons...

Tendon proteoglycans: biochemistry and function.

Abstract: Tendon remodeling occurs in response to changes in loading and mobilization. Though the normal mechanical function depends on precise alignment of collagen fibrils, it is proteoglycans that regulate collagen fibrillogenesis and thus, indirectly, tendon function. In this paper we discuss the basic biochemical structure of several members of two proteoglycans families. Decorin, biglycan, fibromodulin and lumican, all members of the small leucine-rich proteoglycans family, bind to collagen fibrils and are active participants in fibrillogenesis. Aggrecan and versican, two members of large modular proteoglycans or lecticans, and their partner hyaluronan likely provide tendon tissues with a high capacity to resist high compressive and tensile forces associated with loading and mobilization. We present data from our laboratory showing that proteoglycans and glycosaminoglycan content increases not only with growth but also with loading of young avian gastrocnemius tendons. Specifically, an increase in the content of keratan sulfate, chondroitin sulfate and hyaluronan was observed. Moderate exercise for several weeks led not only to a further increase in total proteoglycans content but also to qualitative changes in proteoglycan make up.

Transforming Growth Factors in Solid Human Malignant Neoplasms

Abstract: Surgically removed solid human benign and malignant neoplasms and nonneoplastic tissues were examined for the presence of transforming growth factors (TGFs). TGFs are polypeptide growth factor-like substances which cause the appearance of a reversible neoplastic phenotype in nontransformed, anchorage-dependent cells in culture, including the induction of the ability to grow while suspended in semisolid medium. Acid-ethanol extracts from adenocarcinomas of the breast, colon, kidney, and ovary; fibrosarcoma and leiomyosarcoma; Hodgkin's lymphoma; fibroadenoma of the breast; uterine leiomyoma; and nonneoplastic kidney and lung were found to cause growth in soft agar of both nontransformed mouse AKR-2B and rat NRK cells. This colony-stimulating activity, where tested, was heat and acid stable but was destroyed by trypsin and dithiothreitol treatment, indicating that the activity is due to a polypeptide with disulfide bonds. Extracts from several of the tumors provided sufficient material for purification by molecular sieve chromatography. Peaks of colony-stimulating activity from a Bio-Gel P-60 column eluted with 1 M acetic acid were detected in the M, 3,000 to 25,000 range with the apparent molecular weight varying depending on the type of tumor being studied and the indicator cells used. The data suggest that at least three TGFs are present in human tumors. Evidence is presented differentiating these TGFs into TGFa, which has selective activity for stimulating AKR-2B cells, and TGFn, which has selective activity for stimulating NRK cells. The NGFn activity was further subdivided into a TGFns fraction and TGFnl fraction, denoting small (less than 6,000) and large (12,000 to 20,00) apparent molecular weights, respectively. The TGFa and TGFnl activities were present in malignant and nonneoplastic (kidney and lung) tissue, whereas the TGFns activity predominated in benign neoplasms. These TGFs exhibited no competition with epidermal growth factor for binding to the epidermal growth factor receptor, and the TGFnl activity was potentiated by epidermal growth factor.

Neutrophils and immunity: challenges and opportunities.

Abstract: Scientists who study neutrophils often have backgrounds in cell biology, biochemistry, haematology, rheumatology or infectious disease. Paradoxically, immunologists seem to have a harder time incorporating these host-defence cells into the framework of their discipline. The recent literature discussed here indicates that it is appropriate for immunologists to take as much interest in neutrophils as in their lymphohaematopoietic cousins with smooth nuclei. Neutrophils inform and shape immune responses, contribute to the repair of tissue as well as its breakdown, use killing mechanisms that enrich our concepts of specificity, and offer exciting opportunities for the treatment of neoplastic, autoinflammatory and autoimmune disorders.

Mutations in progranulin cause tau-negative frontotemporal dementia linked to chromosome 17

Abstract: Frontotemporal dementia (FTD) is the second most common cause of dementia in people under the age of 65 years. A large proportion of FTD patients (35-50%) have a family history of dementia, consistent with a strong genetic component to the disease. In 1998, mutations in the gene encoding the microtubule-associated protein tau (MAPT) were shown to cause familial FTD with parkinsonism linked to chromosome 17q21 (FTDP-17). The neuropathology of patients with defined MAPT mutations is characterized by cytoplasmic neurofibrillary inclusions composed of hyperphosphorylated tau. However, in multiple FTD families with significant evidence for linkage to the same region on chromosome 17q21 (D17S1787-D17S806), mutations in MAPT have not been found and the patients consistently lack tau-immunoreactive inclusion pathology. In contrast, these patients have ubiquitin (ub)-immunoreactive neuronal cytoplasmic inclusions and characteristic lentiform ub-immunoreactive neuronal intranuclear inclusions. Here we demonstrate that in these families, FTD is caused by mutations in progranulin (PGRN) that are likely to create null alleles. PGRN is located 1.7 Mb centromeric of MAPT on chromosome 17q21.31 and encodes a 68.5-kDa secreted growth factor involved in the regulation of multiple processes including development, wound repair and inflammation. PGRN has also been strongly linked to tumorigenesis. Moreover, PGRN expression is increased in activated microglia in many neurodegenerative diseases including Creutzfeldt-Jakob disease, motor neuron disease and Alzheimer's disease. Our results identify mutations in PGRN as a cause of neurodegenerative disease and indicate the importance of PGRN function for neuronal survival.

Autocrine growth factors and cancer.

Abstract: The ability of cancer cells to produce and to respond to their own growth factors (autocrine secretion) has become a central concept linking oncogene and growth factor research. Oncogenes confer growth factor autonomy on cells not only by coding directly for autocrine peptide growth factors or their receptors, but also by amplifying the mitogenic signals generated by a growth factor at its receptor. Antagonists of positive autocrine growth factors can inhibit growth of cancer cells in experimental animals. Recently identified negative autocrine growth factors might themselves control aberrant cell growth.

Null mutations in progranulin cause ubiquitin-positive frontotemporal dementia linked to chromosome 17q21

Abstract: Frontotemporal dementia (FTD) with ubiquitin-immunoreactive neuronal inclusions (both cytoplasmic and nuclear) of unknown nature has been linked to a chromosome 17q21 region (FTDU-17) containing MAPT (microtubule-associated protein tau). FTDU-17 patients have consistently been shown to lack a tau-immunoreactive pathology, a feature characteristic of FTD with parkinsonism linked to mutations in MAPT (FTDP-17). Furthermore, in FTDU-17 patients, mutations in MAPT and genomic rearrangements in the MAPT region have been excluded by both genomic sequencing and fluorescence in situ hybridization on mechanically stretched chromosomes. Here we demonstrate that FTDU-17 is caused by mutations in the gene coding for progranulin (PGRN), a growth factor involved in multiple physiological and pathological processes including tumorigenesis. Besides the production of truncated PGRN proteins due to premature stop codons, we identified a mutation within the splice donor site of intron 0 (IVS0 + 5G > C), indicating loss of the mutant transcript by nuclear degradation. The finding was made within an extensively documented Belgian FTDU-17 founder family. Transcript and protein analyses confirmed the absence of the mutant allele and a reduction in the expression of PGRN. We also identified a mutation (c.3G > A) in the Met1 translation initiation codon, indicating loss of PGRN due to lack of translation of the mutant allele. Our data provide evidence that PGRN haploinsufficiency leads to neurodegeneration because of reduced PGRN-mediated neuronal survival. Furthermore, in a Belgian series of familial FTD patients, PGRN mutations were 3.5 times more frequent than mutations in MAPT, underscoring a principal involvement of PGRN in FTD pathogenesis.