The ultrastructural organization and properties of the mouse tectorial membrane matrix

Hasko, J.A; Richardson, Guy P.

doi:10.1016/0378-5955(88)90037-8

Cited by 113 publications

(66 citation statements)

References 13 publications

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“…The biochemical composition of the TM is similar throughout, in both the longitudinal and radial directions (24). Therefore, it is expected that, at resolution scales comparable to a single building block, the structure of the TM will appear very similar in all regions.…”

Section: Resultsmentioning

confidence: 94%

Measurement of the mechanical properties of isolated tectorial membrane using atomic force microscopy

Gueta

Barlam²,

Shneck

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the cochlea. Its strategic location, together with the results of recent TM-specific mutation studies, suggests that it has an important role in the mechanism by which the cochlea transduces mechanical energy into neural excitation. A detailed characterization of TM mechanical properties is fundamental to understanding its role in cochlear mechanics. In this work, the mechanical properties of the TM are characterized in the radial and longitudinal directions using nano-and microindentation experiments conducted by using atomic force spectroscopy. We find that the stiffness in the main body region and in the spiral limbus attachment zone does not change significantly along the length of the cochlea. The main body of the TM is the softest region, whereas the spiral limbus attachment zone is stiffer, with the two areas having averaged Young's modulus values of 37 ؎ 3 and 135 ؎ 14 kPa, respectively. By contrast, we find that the stiffness of the TM in the region above the outer hair cells (OHCs) increases by one order of magnitude in the longitudinal direction, from 24 ؎ 4 kPa in the apical region to 210 ؎ 15 kPa at the basilar end of the TM. Scanning electron microscopy analysis shows differences in the collagen fiber arrangements in the OHC zone of the TM that correspond to the observed variations in mechanical properties. The longitudinal increase in TM stiffness is similar to that found for the OHC stereocilia, which supports the existence of mechanical coupling between these two structures.cochlea ͉ collagen fibers ͉ indentation ͉ hearing T he tectorial membrane (TM) is a heterogeneous and gelatinous extracellular matrix. It is located in the cochlea, which transduces mechanical audio stimuli into an electrical signal. Under physiological conditions, 97% of the weight of the TM is water, whereas the remainder is composed of proteins and protoglycans (1). Nearly half of these proteins are collagens, principally of type II, which form fibrils that are assembled along the radial direction (Fig. 1A); at the surface of the TM, which faces away from the hair-cells, they form a mesh-like structure called the covering net.Structurally, the TM spans the entire length of the cochlea and is Ϸ100 m wide and 50 m thick. It is strategically situated over the sensory cells of the cochlea: the outer (OHCs) and inner (IHCs) hair cells (Fig. 1B). The electromotility of OHCs is thought to play a central role in the cochlear mechanicalelectrical transduction process (2, 3), whereas IHCs synapse directly with the auditory nerve (4). Upon auditory stimulation, deflection of the stereocilium bundles, which exist both in OHCs and IHCs, directly converts the mechanical energy into an electrical signal. This conversion is the physiological function of these cells. An additional function of the OHCs is electromechanical transduction. Whereas the stereocilia of OHCs are physically embedded in the lower surface of the TM, the stereocilia of the IHC ar...

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Section: Resultsmentioning

confidence: 94%

Measurement of the mechanical properties of isolated tectorial membrane using atomic force microscopy

Gueta

Barlam²,

Shneck

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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“…Hasko and Richardson (1988) showed that Ruthenium redstained particles in the early postnatal TM resemble proteoglycan granules, and disappear after postnatal weeks 3-4. Our study also shows that the main body of the TM reacts strongly for most of the lectins at early stages, but only weakly in adults.…”

Section: Tmmentioning

confidence: 99%

“…The molecular composition of the TM has been widely studied and is known to consist of proteins and carbohydrates (Steel, 1980(Steel, , 1986Tomoda et al, 1984;GilLoyzaga et al, 1985;Khalkhali-Ellis et al, 1987;Tachibana et al, 1987;Hasko and Richardson, 1988;Rueda and Lim, 1988;Fermin et al, 1990;Prieto et al, 1990b;25 AugustMunyer and Schulte, 1991;Sugiyama et al, 1991aSugiyama et al, ,b, 1992Suzuki et al, 1992;Kawamata and Igarashi, 1993;Rubio et al, 1994;Munyer and Schulte, 1995;Gil-Loyzaga, 1997;Bianchi et al, 1999). Thalmann et al (1987) demonstrated that type II collagen is the major constituent of the TM protein.…”

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confidence: 99%

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Distribution of glycoconjugates during cochlea development in mice: Light microscopic lectin study

Rueda¹,

Cantos²,

Lim³

2003

Anat. Rec.

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During development, different epithelial cells in the mouse cochlea express different cell surface glycoconjugates, which may reflect membrane specialization. Some of the lectins tested in this study (SBA, succ-WGA, and PSA) labeled the sensory cells of the cochlea around birth. Other lectins (WGA, Con A, RCA-II, and PHA-E) labeled surfaces of the sensory cells, particularly the stereocilia, from early stages of development (gestation day (GD) 16) through 21 days after birth. These may be adhesion molecules needed to attach the newly forming tectorial membrane (TM) to the stereocilia. Lectin staining of the developing TM revealed that the substructures of the TM are biochemically distinct. Lectin staining also showed the temporal sequence of the expression of cytoplasmic glycoconjugates of the cochlear epithelium during development. Biochemical changes during development are probably the result of different cells being involved in the production of glycoconjugates, and may have functional significance, specifically with regard to the expression of adhesion and/or signaling molecules. Anat Rec Part A 274A: 923-933, 2003.

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“…To our knowledge, there is no previous report of PMCA1 in spiral limbus interdental cells, which are thought to contribute to maintenance of the tectorial membrane (TM) (Spicer et al 2000). Chelation of Ca 2+ with EDTA causes swelling of the TM (Kronester -Frei 1979) and loss of its normally organized, striated structure (Hasko and Richardson 1988). Interdental cell PMCA1 might provide localized calcium to help establish or maintain the overlying TM.…”

Section: Immunocytochemistrymentioning

confidence: 99%

Low Endolymph Calcium Concentrations in deafwaddler2J Mice Suggest that PMCA2 Contributes to Endolymph Calcium Maintenance

Wood

Muchinsky

Filoteo

et al. 2004

JARO

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In vertebrates, transduction of sound into an electrochemical signal is carried out by hair cells that rely on calcium to perform specialized functions. The apical surfaces of hair cells are surrounded by endolymphatic fluid containing calcium at concentrations that must be maintained by active transport. The mechanism of this transport is unknown, but an ATPdependent pump is believed to participate. Mutation of the Atp2b2 gene that encodes plasma membrane calcium ATPase type 2 (PMCA2) produces the deaf, ataxic mouse: deafwaddler 2J (dfw 2J ). We hypothesized that PMCA2 might transport calcium into the endolymph and that dfw 2J mice would have low endolymph calcium concentrations, possibly contributing to their deafness and ataxia. First, using immunocytochemistry, we demonstrated that PMCA2 is present in control mice inner and outer hair cell stereocilia where it could pump calcium into the endolymph and that PMCA2 is absent in dfw 2J stereocilia. Second, using an aspirating microelectrode and calcium-sensitive fluorescent dye, we found that dfw 2J mice endolymph calcium concentrations are significantly lower than those of control mice. These findings suggest that PMCA2, located in hair cell stereocilia, contributes significantly to endolymph calcium maintenance.

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The ultrastructural organization and properties of the mouse tectorial membrane matrix

Cited by 113 publications

References 13 publications

Measurement of the mechanical properties of isolated tectorial membrane using atomic force microscopy

Measurement of the mechanical properties of isolated tectorial membrane using atomic force microscopy

Distribution of glycoconjugates during cochlea development in mice: Light microscopic lectin study

Low Endolymph Calcium Concentrations in deafwaddler2J Mice Suggest that PMCA2 Contributes to Endolymph Calcium Maintenance

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