Biomedical subjects

Ruben Mestril

Publications and source records attributed to Ruben Mestril.

23 records · Page 2Linked to original sources

PubMed2003

Hsp10 and Hsp60 suppress ubiquitination of insulin-like growth factor-1 receptor and augment insulin-like growth factor-1 receptor signaling in cardiac muscle: implications on decreased myocardial protection in diabetic cardiomyopathy.

We have investigated the effects of two heat shock proteins, Hsp10 and Hsp60, on insulin-like growth factor-1 receptor (IGF-1R) signaling in cardiac muscle cells. Neonatal cardiomyocytes were transduced with Hsp10 or Hsp60 via adenoviral vector. Compared with the cells transduced with a control vector, overexpression of Hsp10 or Hsp60 increased the abundance of IGF-1R and IGF-1-stimulated receptor autophosphorylation. Thus, Hsp10 and Hsp60 overexpression increased the number of functioning receptors and amplified activation of IGF-1R signaling. IGF-1 stimulation of MEK, Erk, p90Rsk, and Akt were accordingly augmented. Transducing cardiomyocytes with antisense Hsp60 oligonucleotides reduced Hsp60 expression, decreased the abundance of IGF-1R, attenuated IGF-1R autophosphorylation, and suppressed the pro-survival action of IGF-1 in cardiomyocytes. Using cycloheximide to inhibit protein synthesis did not alter the effect of Hsp60 on IGF-1R signaling, and IGF-1R mRNA levels were not up-regulated by Hsp10 or Hsp60. Additional experiments showed that Hsp10 and Hsp60 suppressed polyubiquitination of IGF-1 receptor. These data indicate that Hsp10 and Hsp60 can modulate IGF-1R signaling through post-translational modification. In animal models of diabetes, diabetic myocardium is associated with decreased abundance of Hsp60, increased ubiquitination of IGF-1R, and lower level of IGF-1R protein. Declined myocardial protection is a major feature of diabetic cardiomyopathy. These data suggest that decreased Hsp60 expression and subsequent decline of IGF-1R signaling may be a fundamental mechanism underlying the development of diabetic cardiomyopathy.

Adenoviridae↗

PubMed2003

Hsp10 and Hsp60 modulate Bcl-2 family and mitochondria apoptosis signaling induced by doxorubicin in cardiac muscle cells.

The development of doxorubicin cardiomyopathy involves apoptosis of cardiac muscle cells. This study was carried out to define the roles of two heat-shock proteins, Hsp10 and Hsp60, on doxorubicin-induced apoptosis in primary cardiomyocytes. Doxorubicin induces apoptosis of cardiomyocytes by activating mitochondria apoptosis signaling. Transducing cardiomyocytes with Hsp10 or Hsp60 with adenoviral vector suppressed the occurrence of apoptosis in the doxorubicin-treated cardiomyocytes. Overexpression of Hsp10 and Hsp60 increased the abundance of the anti-apoptotic Bcl-xl and Bcl-2, and reduced the protein content of the pro-apoptotic Bax. Hsp60 overexpression also significantly reduced doxorubicin induction of Bad, whereas overexpression of Hsp10 did not alter the expression of Bad in the doxorubicin-treated cells. Overexpression of Hsp10 and Hsp60, respectively, stabilized mitochondrial cross-membrane potential, inhibited Caspase 3, and suppressed PARP. These findings indicate that overexpression of Hsp10 and Hsp60 differentially modulated Bcl-2 family and in turn attenuate doxorubicin-induced cardiac muscle death. The effects of Hsp10 and Hsp60 on Bcl-2 family could not be explained by the abundance of Bcl-2 family mRNA levels. Hsp60 interacted with Bcl-xl and Bax in the cardiomyocytes in vivo. The effect of Hsp10 and Hsp60 on the abundance of Bcl-xl could not be blocked by cycloheximide. Moreover, Hsp10 and Hsp60 inhibited ubiquitination of Bcl-xl. These findings suggest that Hsp10 and Hsp60 modulated post-translational modification of Bcl-xl. Antisense Hsp60 reduced the abundance of endogenous Hsp60 in cardiomyocytes and amplified the cytotoxicity of doxorubicin. These data provide a novel link between Hsp10/Hsp60 and cardiac protection in doxorubicin cardiomyopathy.

Adenoviridae↗

PubMed2003

Overexpression of heat shock proteins differentially modulates protein kinase C expression in rat neonatal cardiomyocytes.

Previous studies have suggested that protein kinase C (PKC) is involved in heat shock protein (Hsp)-mediated cardioprotection. Therefore, we wanted to determine whether overexpression of Hsps modulates PKC expression, which will give us further insight into understanding the mechanism by which Hsps and PKC interact to protect cells from stress-induced injury. Specifically, we overexpressed the inducible form of Hsp70 (Hsp70i) or Hsp90 in rat neonatal cardiomyocytes and evaluated PKCdelta or PKCepsilon expression by immunoblotting and immunofluorescent confocal microscopy. Western analysis showed that overexpression of Hsp70i or Hsp90 decreased PKCepsilon expression. However, overexpression of Hsp70i or Hsp90 did not modify PKCdelta expression over control levels. Overexpression of constitutively active PKCdelta or PKCepsilon increased Hsp70i expression over control levels. The data suggest that overexpression of Hsps differentially modulates expression of PKC isoforms in rat neonatal cardiomyocytes. Furthermore, PKC may directly play a role in Hsp-mediated cardioprotection by upregulating Hsp70i expression.

Adenoviridae↗

PubMed2002

Losing heart: the role of apoptosis in heart disease--a novel therapeutic target?

Cardiovascular disease is a leading cause of death worldwide. In recent years it has emerged that loss of myocardial cells may be a major pathogenic factor. Cell death can occur in a destructive, uncontrolled manner via necrosis or by a highly regulated programmed cell suicide mechanism termed apoptosis. As cell death in conditions such as heart failure and myocardial infarction does not always follow a typically apoptotic pathway, it remains to be established whether it occurs by apoptosis, necrosis, or a novel uncharacterized mechanism combining aspects of both types of cell death. Apoptotic pathways have been well studied in nonmyocytes and it is thought that similar pathways exist in cardiomyocytes. These pathways include death initiated by ligation of membrane-bound death receptors or death initiated by release of cytochrome c from mitochondria. Increasing evidence supports the existence of these pathways and their regulators in the heart. These regulators include inhibitors of caspases, which are the key enzymes of apoptosis, the Bcl-2 family of proteins, growth factors, stress proteins, calcium, and oxidants. It is hoped that a better understanding of the pathways of apoptosis and their regulation may yield novel therapeutic targets for cardiovascular disease.

Animals↗

PubMed2002

Mutation of COOH-terminal lysines in overexpressed alpha B-crystallin abrogates ischemic protection in cardiomyocytes.

High levels of alpha B-crystallin are present in the cardiomyocyte, yet little is understood about the function and importance of this protein. Like many other small heat shock proteins, alpha B-crystallin forms large oligomeric complexes whose size can be regulated by posttranslational modifications. The size of these complexes can modify the function of the protein. A naturally occurring COOH-terminal mutant has many detrimental effects in the lens of the eye and altered oligomerization. Therefore, we mutated the two COOH-terminal lysines of alpha B-crystallin to glycines (K174/175G) and adenovirally mounted them to transduce cardiomyocytes. We analyzed the effect of this mutation on oligomerization, microtubular stabilization, and ischemic outcome. A nearly 45% downward shift in complex size was observed with the mutant by native PAGE followed by immunoblotting. The overexpressed protein no longer protected the tubulin cytoskeleton against ischemic stress by confocal analysis. The mutant caused a 30% increase in cytosolic enzyme release with ischemia compared with control, whereas a 33% decrease was associated with wild-type alpha B-crystallin overexpression. We conclude that the COOH terminus of alpha B-crystallin is crucial to its proper function.

Animals↗