Open Access

Inhibition of calpain but not caspase activity by spectrin fragments

  • Ramunas Rolius1,
  • Chloe Antoniou1, 2,
  • Lidia A. Nazarova1,
  • Stephen H. Kim1,
  • Garrett Cobb1,
  • Pooja Gala1,
  • Priyanka Rajaram1,
  • Qufei Li1, 2 and
  • Leslie W.-M. Fung1Email author
Cellular & Molecular Biology LettersAn International Journal201015:15

DOI: 10.2478/s11658-010-0015-3

Received: 26 February 2010

Accepted: 25 April 2010

Published: 14 May 2010

Abstract

Calpains and caspases are ubiquitous cysteine proteases that are associated with a variety of cellular pathways. Calpains are involved in processes such as long term potentiation, cell motility and apoptosis, and have been shown to cleave non-erythroid (brain) α- and β-spectrin and erythroid β-spectrin. The cleavage of erythroid α-spectrin by calpain has not been reported. Caspases play an important role in the initiation and execution of apoptosis, and have been shown to cleave non-erythroid but not erythroid spectrin. We have studied the effect of spectrin fragments on calpain and caspase activities. The erythroid and non-erythroid spectrin fragments used were from the N-terminal region of α-spectrin, and C-terminal region of β-spectrin, both consisting of regions involved in spectrin tetramer formation. We observed that the all spectrin fragments exhibited a concentration-dependent inhibitory effect on calpain, but not caspase activity. It is clear that additional studies are warranted to determine the physiological significance of calpain inhibition by spectrin fragments. Our findings suggest that calpain activity is modulated by the presence of spectrin partial domains at the tetramerization site. It is not clear whether the inhibitory effect is substrate specific or is a general effect. Further studies of this inhibitory effect may lead to the identification and development of new therapeutic agents specifically for calpains, but not for caspases. Proteins/peptides with a coiled coil helical conformation should be studied for potential inhibitory effects on calpain activity.

Key words

Spectrin Calpain Caspase Calpain inhibition Cysteine protease

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