Effect of recombinant porcine IGF-binding protein-3 on proliferation of embryonic porcine myogenic cell cultures in the presence and absence of IGF-I

Abstract

IGF-binding protein (IGFBP)-3 is produced by cultured porcine embryonic myogenic cell (PEMC) cultures and is secreted into the medium. Levels of secreted IGFBP-3 and IGFBP-3 mRNA are significantly reduced during differentiation and increase after differentiation is complete, suggesting that IGFBP-3 may play some role in myogenesis and/or in changes in myogenic cell proliferation that accompany differentiation. IGFBP-3 reportedly may either suppress or stimulate proliferation of cultured cells depending on cell type. Additionally, IGFBP-3 has been shown to affect proliferation via both IGF-dependent and IGF-independent mechanisms in some cell types but not all. Currently, the effect, if any, of IGFBP-3 on myogenic cell proliferation is not known. Consequently, the goal of this study was to assess the IGF-I-dependent and IGF-Iindependent actions of recombinant porcine IGFBP-3 on proliferation of cultured porcine myogenic cells. To facilitate these investigations, we have expressed porcine IGFBP-3 in the baculovirus system, purified and characterized the expressed recombinant porcine IGFBP-3 (rpIGFBP-3), and produced and characterized an antiporcine IGFBP-3 antibody that neutralizes the biological activity of porcine IGFBP-3. rpIGFBP-3 suppressed IGF-I-stimulated proliferation of PEMCs in a concentration-dependent manner with equimolar concentrations of IGF-I and rpIGFBP-3, resulting in complete suppression of IGF-I-stimulated proliferation. rpIGFBP-3 also suppressed Long-R3-IGF-I-stimulated proliferation of PEMC, indicating that rpIGFBP-3 possesses IGFindependent activity in this cell system. These data have established that IGFBP-3 has the potential to affect proliferation of PEMCs during critical periods of muscle development that may impact ultimate muscle mass achievable postnatally.

Comparison of the effects of the n-3 polyunsaturated fatty acid eicosapentaenoic and fenofibrate on the inhibitory effect of arthritis on IGF1

“…The increased expression of Igfbp3 in the gastrocnemius of arthritic rats has been related to muscle atrophy. This hypothesis is based on the fact that IGFBP3 prevents IGF1 from binding to its receptor and it is able to inhibit cell proliferation by an IGF1-independent mechanism (Pampusch et al 2003). IGFBP5 can also inhibit IGF1 action by preventing its binding to its receptors in the skeletal muscle (Mukherjee et al 2008).…”

Cellular and molecular mechanisms underlying age-related skeletal muscle wasting and weakness

“…While the predominant source of circulating IGFBPs is the liver, skeletal muscle myoblasts undergoing differentiation produce and release IGFBP-2, 3, 4 and 5 (Foulstone et al 2003;Pampusch et al 2003). While the precise role of these IGFBPs in the control of skeletal muscle growth and development has yet to be elucidated, the disruption of IGFBP expression has been found to impair myoblast proliferation, differentiation and maturation (Fligger et al 1998;Foulstone et al 2003;Pampusch et al 2003Pampusch et al , 2005. Benbassat et al (1997) examined the protein levels of circulating IGFBPs and reported a two-fold increase in IGFBP1 and an *15% decrease in IGFBP3, in old compared with young men (Table 1).…”

Dynamic transcriptional regulation of autocrine/paracrine igfbp1, 2, 3, 4, 5, and 6 in the skeletal muscle of the fine flounder during different nutritional statuses

“…Locally produced IGFBP3 shows a different dynamic in muscle. This binding protein is not the most abundant IGFBP in muscle and shows both IGF-dependent actions by stimulating myoblast differentiation (Foulstone et al 2003), IGF-independent actions, and suppressing cell proliferation (Pampusch et al 2003). In fish, the role of Igfbp3 in skeletal muscle has not been defined, and no studies have investigated its expression during fasting and refeeding.…”