Intracellular Hyaluronan in Arterial Smooth Muscle Cells: Association with Microtubules, RHAMM, and the Mitotic Spindle

Abstract

S U M M A R YAlthough considered a pericellular matrix component, hyaluronan was recently localized in the cytoplasm and nucleus of proliferating cells, supporting earlier reports that hyaluronan was present in locations such as the nucleus, rough endoplasmic reticulum, and caveolae. This suggests that it can play roles both inside and outside the cell. Hyaluronan metabolism is coupled to mitosis and cell motility, but it is not clear if intracellular hyaluronan associates with cytoskeletal elements or plays a structural role. Here we report the distribution of intracellular hyaluronan, microtubules, and RHAMM in arterial smooth muscle cells in vitro. The general distribution of intracellular hyaluronan more closely resembled microtubule staining rather than actin filaments. Hyaluronan was abundant in the perinuclear microtubule-rich areas and was present in lysosomes, other vesicular structures, and the nucleolus. Partially fragmented fluorescein-hyaluronan was preferentially translocated to the perinuclear area compared with high-molecular-weight hyaluronan. In the mitotic spindle, hyaluronan colocalized with tubulin and with the hyaladherin RHAMM, a cell surface receptor and microtubule-associated protein that interacts with dynein and maintains spindle pole stability. Internalized fluorescein-hyaluronan was also seen at the spindle. Following telophase, an abundance of hyaluronan near the midbody microtubules at the cleavage furrow was also noted. In permeabilized cells, fluorescein-hyaluronan bound to RHAMM-associated microtubules. These findings suggest novel functions for hyaluronan in cellular physiology.

Hyaluronic acid hydrogel for controlled self-renewal and differentiation of human embryonic stem cells

“…1A). These findings are consistent with previous evidence that HA is localized intracellularly, in endosomes and perinuclear tubular vesicles, rough endoplasmic reticulum, nuclei, and nucleoli (24)(25)(26). We therefore investigated whether the success of MEF feeder layers for the cultivation of hESCs might be related to their ability to secrete HA.…”

Hyaluronan-dependent pericellular matrix☆

“…We have previously observed intracellular hyaluronan in close proximity to nuclear clefts and furrows, as well as binding of exogenous hyaluronan to nucleoli [88]. There are also several observations of a close relationship between intracellular hyaluronan, hyaluronan receptors and structural elements such as microtubules and the microtubule-associated HA receptor RHAMM [88,89,106]. Other studies show that RHAMM, possibly through interactions with intracellular hyaluronan or hyaluronan in the cell coat, plays a role in regulating microtubule activity and stabilization of the mitotic spindle [107].…”

“…Rapid uptake of the hyaluronan and translocation to the nucleus, with signaling mediated through RHAMM, was associated with increased motility. In addition to being concentrated in the pericellular matrix, hyaluronan is also internalized in premitotic cells and co-distributes around the mitotic spindle with microtubuleassociated RHAMM [88,89]. Microtubules are compression-bearing elements of the cytoskeleton that target focal adhesions for dissolution [90].…”

Typical and atypical trafficking pathways of Ad5 penton base recombinant protein: implications for gene transfer

“…13 Dynein typically mediates the transport of vesiculated cargo along microtubule tracks from the cell periphery to various subcellular locations, including lysosomes and the nucleus. [19][20][21] Dynein has been implicated more recently in the transport of naked viral capsids from endosomes to the nuclear periphery. 13 To determine whether dynein is required for PB translocation, we transfected HeLa cells with a plasmid overexpressing the p50/dynamitin (p50/dyn) subunit of dynein, which results in disruption of the dynein motor complex.…”