Disease relevance of CAPN1

• Calpain activity decreased as cataracts progressed [1].
• These data suggest that calpastatin activity rather than the activity of either calpain isoform is closely linked to beta-agonist-induced muscle hypertrophy [2].
• Release of undegraded alpha-actinin and autolysis are properties specific to the calpains, and it is unclear whether some of the myofibril-bound proteolytic activity originates from proteases other than the calpains or whether the active site of myofibril-bound calpain is shielded from the inhibitors [3].

High impact information on CAPN1

• Degradation of calpain substrates spectrin and vimentin was assessed by immunoblotting [1].
• The results of this study support the possibility that a sustained elevation in resting Ca(2+)(i) is one of the factors controlling lens cell differentiation, possibly by triggering events such as calpain activation [4].
• In contrast, the GABA uptake inhibition observed at high Ca2+ concentrations (1 mM) is less specific, and probably it is partially related to the proteolytic activity of membrane bound calpain II [5].
• The aim of the present study was to examine the effect of a short period of cimaterol (feeding for 8 days, followed by reversion to a normal diet for a further 24 days) on muscle growth and on calpain isoform and calpastatin activities and specific mRNA abundance in the longissimus dorsi (LD) muscle [2].
• The relationship between genotype, level of nutrition, muscle protein turnover and the calpain system in young milk-fed lambs was assessed [6].

Chemical compound and disease context of CAPN1

• The myofibril-bound calpain degrades desmin, nebulin, titin, and troponin T in the myofibrils, and also releases undegraded alpha-actinin and undergoes additional autolysis when incubated with Ca2+; all these activities occurred slowly considering the amount of myofibril-bound calpain [3].

Biological context of CAPN1

• The results revealed that calpain II gene expression was similar in the three tissues [7].
• It is unclear whether this low specific activity is the result of unavailability of the active site of the myofibril-bound calpain to exogenous substrate [3].

Anatomical context of CAPN1

• Transient changes in growth and in calpain and calpastatin expression in ovine skeletal muscle after short-term dietary inclusion of cimaterol [2].
• The calpain is bound tightly, and very little is removed by washing with the detergent Triton X-100; hence, it is not bound to phospholipids in the myofibril [3].
• The supraspinatus (SPM), longissimus (LM), and semitendinosus (STM) muscles were analyzed to determine callipyge effects on calpain and calpastatin activities, sarcomere length, percentage of muscle fiber types, and muscle fiber areas [8].

Associations of CAPN1 with chemical compounds

• The relation between dietary restriction or clenbuterol (a selective beta 2 agonist) treatment on muscle growth and calpain proteinase (EC 3.4.22.17) and calpastatin activities in lambs [9].
• Dietary administration of 4 ppm of the beta-agonist L-644,969 (Merck Sharpe and Dohme Research Laboratories) to finishing lambs induced a decrease (10 to 14%, P less than .05) in extractable calpain I activity in the longissimus muscle (LD) at death (d 0) [10].
• Activity of the myofibril-bound calpain was partly (58 to 67%) inhibited by the calpain inhibitors, E-64 and iodoacetate; was more effectively inhibited by a broader-based protease inhibitor, leupeptin (84 to 89%); and was poorly inhibited (43 to 45%) by calpastatin [3].

Other interactions of CAPN1

• Muscle calpastatin activity was severa fold higher than calpain I and II activities [11].

Analytical, diagnostic and therapeutic context of CAPN1

• The presence of calpain was detected by casein zymography and immunoblotting [1].
• Hence, castration did not influence lamb muscle growth by altering muscle calpain or calpastatin activities [11].
• Calpastatin ELISA results were linearly related to calpastatin activity (calpain inhibitory activity) of heated longissimus muscle homogenates from prerigor lamb (r2 = .89; n = 40) and beef aged for 24 or 48 h (r2 = .90; n = 47) [12].
• Therefore, the unacceptable variation found in Exp. 1 resulted from the small sample size, and we recommend that large tissue samples (e.g., 50 g) should be used for calpain and calpastatin activity measurements in skeletal muscle instead of small tissue biopsies (e.g., 0.2 and 1.0 g) [13].

References