Progressive resistance-loaded voluntary wheel running increases hypertrophy and differentially affects muscle protein synthesis, ribosome biogenesis, and proteolytic markers in rat muscle.

We examined if 6 weeks of progressive resistance-loaded voluntary wheel running in rats induced plantaris, soleus, and/or gastrocnemius hypertrophy and/or affected markers of translational efficiency, ribosome biogenesis, and markers of proteolysis. For 6 weeks, 8 male Sprague-Dawley rats (~9-10 weeks of age, ~300-325 g) rats were assigned to the progressive resistance-loaded voluntary wheel running model (EX), and ten rats were not trained (SED). For EX rats, the wheel-loading paradigm was as follows - days 1-7: free-wheel resistance, days 8-15: wheel resistance set to 20%-25% body mass, days 16-24: 40% body mass, days 25-32: 60% body mass, days 33-42: 40% body mass. Following the intervention, muscles were analysed for markers of translational efficiency, ribosome biogenesis, and muscle proteolysis. Raw gastrocnemius mass (+13%, p < .01), relative (body mass-corrected) gastrocnemius mass (+16%, p < .001), raw plantaris mass (+13%, p < .05), and relative plantaris mass (+15%, p < .01) were greater in EX vs. SED rats. In spite of gastrocnemius hypertrophy, EX animals presented a 54% decrease in basal muscle protein synthesis levels (p < .01), a 125% increase in pan 4EBP1 levels (p < .001) and a 31% decrease in pan eIF4E levels (p < .05). However, in relation to SED animals, EX animals presented a 70% increase in gastrocnemius c-Myc protein levels (p < .05). Most markers of translational efficiency and ribosome biogenesis were not altered in the plantaris or soleus muscles of EX vs. SED animals. Gastrocnemius F-box protein 32 and poly-ubiquinated protein levels were approximately 150% and 200% greater in SED vs. EX rats (p < .001). These data suggest that the employed resistance training model increases hind limb muscle hypertrophy, and this may be mainly facilitated through reductions in skeletal muscle proteolysis, rather than alterations in ribosome biogenesis or translational efficiency.

Adoptive precursor cell therapy to enhance immune reconstitution after hematopoietic stem cell transplantation.

Strategies to enhance post-transplant immune reconstitution without aggravating graft-vs-host disease (GVHD) can improve the outcome of allogeneic hematopoietic stem cell transplantation. Recent preclinical studies demonstrated that the use of T cell depleted allografts supplemented with committed progenitor cells (vs stem cells only) allows enhanced immune reconstitution of specific hematopoietic lineages including myeloid, B, T, and natural killer lineages in the absence of GVHD. This novel adoptive therapy resulted in significantly improved resistance to microbial pathogens and could, in some cases, even mediate tumor immunity. Clinical protocols using adoptive transfer of committed hematopoietic progenitor cells are currently being evaluated.

Kallikrein gene expression in the gonadotrophin-stimulated rat ovary.

The kallikreins (KLKs) are a highly conserved multi-gene family of serine proteases that are expressed in a wide variety of tissues and act on a diverse range of substrates. KLK-like enzyme activity has variously been reported to increase or decrease during the period leading up to ovulation in the equine chorionic gonadotrophin (eCG)primed, human chorionic gonadotrophin (hCG)-stimulated immature rat ovary. These earlier studies, which used biochemical assays to detect enzyme activity, lacked the specificity and sensitivity necessary to characterise conclusively the activity of the individual KLK gene family members. In this study, we have used a gene-specific RT-PCR/Southern hybridisation strategy to delineate the expression patterns of six of the individual KLK genes expressed in the rat ovary (rKLK1-3 and rKLK7-9). We have identified three broad patterns of expression in the eCG/hCG-stimulated ovary in which there is either a post-eCG increase/pre-ovulatory decrease in rKLK expression (rKLK1, rKLK3), a peri-ovulatory decrease in expression (rKLK2, rKLK8) or a relatively unchanged pattern of expression (rKLK7, rKLK9). In addition to clarifying the earlier biochemical studies, these findings support a differential role for the individual KLKs in the ovulatory process.

Kallikrein gene family expression in the rat ovary: localization to the granulosa cell.

The glandular or tissue kallikreins are a multigene family of serine proteases, of which 13 genes (rKLK1-13) have been identified in the rat and are expressed in a wide variety of tissues. Kallikrein-like enzyme activity has been detected during the periovulatory period in the gonadotropin-primed immature female rat ovary and suggested to play a role in the inflammatory-like response at ovulation. In this study, we examined whether this enzyme activity was due to local expression of a rat KLK gene family member. Ovarian RNA, prepared from gonadotropin-treated animals, was assessed for rKLK gene expression by reverse transcriptase-polymerase chain reaction (RT-PCR) with universal rKLK primers derived from highly conserved regions in the rat KLK genes. Southern blot analysis of the RT-PCR products, using oligonucleotide probes specific for the individual genes, indicated that five rKLK gene family members, rKLK1 (encoding true kallikrein), rKLK3, rKLK7, rKLK8, and rKLK9, were expressed at varying levels in the ovaries of both untreated control and gonadotropin-treated immature female rats. The identities of these five rKLK messenger RNAs were further confirmed by DNA sequence analysis of the PCR products. In situ hybridization of gonadotropin-treated ovaries localized rKLK3 and rKLK7 gene expression to the luteinizing granulosa cells of periovulatory follicles. In an enriched population of nonluteinizing granulosa cells prepared from estrogen-primed animals, we also demonstrated rKLK3, rKLK7, rKLK9, and rKLK12 (but not rKLK1 or rKLK8) expression, whereas all six genes were expressed in the ovaries of these animals. In summary, we have reported the expression of six KLK gene family members in the rat ovary and localized this expression primarily to the granulosa cell. The potential roles of these enzymes in ovulation or other aspects of ovarian, particularly granulosa cell, function are yet to be elucidated.