Association of HSPB2, a member of the small heat shock protein family, with mitochondria

Midori Nakagawa, Naomi Tsujimoto, Hiroyuki Nakagawa, Toru Iwaki, Yasuyuki Fukumaki, Akiko Iwaki

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)

Abstract

We previously identified HSPB2, a new member of the small heat shock protein family, expressed in heart and skeletal muscles. In this study, we used a polyclonal anti-HSPB2 antibody and examined the subcellular localization of HSPB2 in differentiated C2C12 cells, KNS-81 cells, and NIH3T3 transfectants expressing human HSPB2. Double staining with anti-HSPB2 and various markers for cytoplasmic structures showed that HSPB2 was present in the cytosol as granules, some of which colocalized with mitochondria. This colocalization was not altered by a colchicine treatment, indicating that it is independent of microtubules. The subcellular fractionation of differentiated C2C12 cells revealed that HSPB2 was mainly detected in the postmitochondrial supernatant, but mild heat treatment enriched the amount of HSPB2 in the mitochondrial fraction. The expression of HSPB2 protected the cells from heat-induced cell death. In addition, Northern blot analysis revealed that expression of HSPB2 mRNA is higher in slow-twitch muscle than in fast-twitch muscle, which correlates with the amounts of mitochondria present in these two types of tissue. Taken together, these results suggest that HSPB2 may not localize in the matrix, but rather associates with the outer membrane components of the mitochondria and thus plays a role in the stress response.

Original languageEnglish
Pages (from-to)161-168
Number of pages8
JournalExperimental Cell Research
Volume271
Issue number1
DOIs
Publication statusPublished - Nov 15 2001

All Science Journal Classification (ASJC) codes

  • Cell Biology

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