Unique, concentrically laminated, membranous inclusions in myofibers

Formation of Hirano bodies induced by expression of an actin cross-linking protein with a gain-of-function mutation

Hirano bodies are paracrystalline actin filament-containing structures reported to be associated with a variety of neurodegenerative diseases. However, the biological function of Hirano bodies remains poorly understood, since nearly all prior studies of these structures were done with postmortem samples of tissue. In the present study, we generated a full-length form of a Dictyostelium 34-kDa actin cross-linking protein with point mutations in the first putative EF hand, termed 34-kDa DeltaEF1. The 34-kDa DeltaEF1 protein binds calcium normally but has activated actin binding that is unregulated by calcium. The expression of the 34-kDa DeltaEF1 protein in Dictyostelium induces the formation of Hirano bodies, as assessed by both fluorescence microscopy and transmission electron microscopy. Dictyostelium cells bearing Hirano bodies grow normally, indicating that Hirano bodies are not associated with cell death and are not deleterious to cell growth. Moreover, the expression of the 34-kDa DeltaEF1 protein rescues the phenotypes of cells lacking the 34-kDa protein and cells lacking both the 34-kDa protein and alpha-actinin. Finally, the expression of the 34-kDa DeltaEF1 protein also initiates the formation of Hirano bodies in cultured mouse fibroblasts. These results show that the failure to regulate the activity and/or affinity of an actin cross-linking protein can provide a signal for the formation of Hirano bodies. More generally, the formation of Hirano bodies is a cellular response to or a consequence of aberrant function of the actin cytoskeleton.

Formation of Hirano bodies in Dictyostelium and mammalian cells induced by expression of a modified form of an actin-crosslinking protein

We report the serendipitous development of the first cultured cell models of Hirano bodies. Myc-epitope-tagged forms of the 34 kDa actin bundling protein (amino acids 1-295) and the CT fragment (amino acids 124-295) of the 34 kDa protein that exhibits activated actin binding and calcium-insensitive actin filament crosslinking activity were expressed in Dictyosteliumand mammalian cells to assess the behavior of these modified forms in vivo. Dictyostelium cells expressing the CT-myc fragment: (1) form ellipsoidal regions that contain ordered assemblies of F-actin, CT-myc, myosin II, cofilin and α-actinin; (2) grow and develop more slowly than wildtype, but produce normal morphogenetic structures; (3) perform pinocytosis and phagocytosis normally; and (4) produce a level of total actin equivalent to wildtype, but a higher level of F-actin. The paracrystalline inclusions bear a striking resemblance to Hirano bodies, which are associated with a number of pathological conditions. Furthermore, expression of the CT fragment in murine L cells results in F-actin rearrangements characterized by loss of stress fibers, accumulation of numerous punctate foci, and large perinuclear aggregates, the Hirano bodies. Thus, failure to regulate the activity and/or affinity of an actin crosslinking protein can provide a signal for formation of Hirano bodies. More generally, formation of Hirano bodies is a cellular response to or a consequence of aberrant function of the actin cytoskeleton. The results reveal that formation of Hirano bodies is not necessarily related to cell death. These cultured cell models should facilitate studies of the biochemistry, genetics and physiological effects of Hirano bodies.

The myopathology of Behçet's disease--a histochemical, light-, and electron-microscopic study

The myopathology of Behçet's disease is described in 7 patients using conventional light microscopy, histochemistry, high-resolution light microscopy and electron microscopy. Two patients had clinical evidence of peripheral neuropathy: 5 patients had no clinical evidence of neuromuscular involvement. Histochemical profile of muscle in all patients was normal. Abnormalities in muscle histology using conventional light microscopy were found in only 1 patient. High-resolution light microscopy revealed abnormalities in 3 patients whereas electron microscopy revealed abnormalities in muscle of all 7 patients. The myopathology of Behçet's disease includes thickening of capillary basement membrane, excessive pleating of sarcolemma, subsarcolemmal aggregates of mitochondria and glycogen, disorganization and breakdown of myofibrils, central nucleation and the presence of a variety of cytoplasmic inclusions. No virus particles were present.

Mixed nemaline-mitochondrial "myopathy"

A 4-year-old boy suffering from a nonprogressive muscular weakness had a muscle biopsy which ultrastructurally showed large aggregates of nemaline bodies and mitochondria in myofibers; occasional concentric lamellated bodies were present as well. The mitochondria were mostly at the periphery of collections of nemaline bodies, less commonly in their central portions. The light microscopic features differed from those of either nemaline or mitochondrial myopathy and were somewhat reminiscent of multicore disease. Evidence suggestive of possible neurogenic origin of both rods and mitochondria is reviewed.

Hirano bodies in the axon of peripheral nerves in a case with progressive external ophthalmoplegia with multisystemic involvements

Inclusions, ultrastructurally identical with Hirano bodies which were previously believed to be limited to the central nervous system (CNS), were found both within peripheral myelinated nerve axons and within terminal axons of neuromuscular junctions in the ocular muscles of an autopsied woman who had suffered from progressive external ophthalmoplegia with multisystemic involvements. Electron micrographs showed the inclusions to consist of beaded filaments or lattice-like structures with filamentous elements continuing onto neurofilaments in the axon. The corelation of these new pathological findings in peripheral nerve axons and ophthalmoplegia is discussed.

Morphogenesis of the Hirano body in neurons of the squirrel monkey dorsal horn

Electron microscopic investigation of laminae I-III in the lumbosacral region of the squirrel monkey spinal cord has disclosed possible stages in the morphogenesis of the Hirano body. These bodies occur occasionally in nerve cell bodies and dendrites. They are round to oval in shape, measure up to 2.2 micrometer in diameter and are composed of circular layers of 10 nm filaments. In several instances in the present study, Hirano bodies were observed in close association with the Golgi apparatus. Here Golgi-related vesicles were attached to the external surface of the Hirano bodies. In one instance a cluster of developing Hirano bodies of various sizes was observed. The smaller bodies were located nearest the Golgi apparatus while the larger were further away. In this case several short filaments, which may be precursors of the longer filaments which make up the layers of the inclusion, were observed in the cytoplasm between the Golgi cisternae and the smaller Hirano bodies. These observations suggest that the Golgi apparatus plays a major role in the production of the Hirano body. The significance of the occurrence of these inclusions is discussed.

Concentric laminated bodies. Ultrastructural demonstration of muscle fiber type specificity

Concentric laminated bodies were identified in the skeletal muscle of 3 children affected by muscle weakness and hypotonia with probable cerebral involvement. The mean Z-line and M-line widths from each of 11 muscle fibers containing the concentric laminated bodies were calculated. The mean Z-line widths were 61-81 nm and the mean M-line widths from 7 out of 11 fibers were 54-65 nm. According to our present system of fiber typing, the majority of these fibers would be classified as subtype IIB. The possible pathogenesis and fiber type specificity of the concentric laminated body is discussed.

The pathology of type II skeletal muscle glycogenosis. A light and electron-microscopic study

Muscle biopsies were obtained from three infants under the age of 12 mth, each of whom was diagnosed as having Pompe's disease. The biopsies revealed a severe vacuolar myopathy with accumulation of large amounts of PAS positive material within the muscle fibres, changes similar to those in adult cases of the disease. In addition large amounts of metachromatic material were found within the muscle fibres in all three cases and in two of them scattered, rather sparse perivascular lymphocytic infiltrates were seen in the interstitial tissue. Review of material previously obtained from two adult cases showed no accumulation of metachromatic material in the older case and only moderate amounts in the younger. However, dense interstitial lymphocytic infiltrates were seen in the former, some concentrated around small vessels. These observations suggest that the pathogenesis of the muscle disorder in acid maltase deficiency may not depend on abnormal glycogen storage only.

Unusual, rod-shaped cytoplasmic inclusions (Hirano bodies) in a cerebellar hemangioblastoma

The present study reports unusual, long, tubular, rod-shaped cytoplasmic inclusions found in the stromal cells of a cerebellar hemangioblastoma, associated with von Hippel-Lindau syndrome. These inclusions have two layers of circular, laminated filaments, and longitudinally arranged filaments; and appear similar to the so-called "Hirano bodies", which have been previously found in normal and various pathologic conditions of the brain tissue, skeletal muscle cells in myopathy, and interstitial cells of the testis. A review of previous ultrastructural studies of cerebellar hemangioblastoma shows several different types of cytoplasmic inclusions, but none are found to be identical to the present report.