Distinct immunoreactivities suggest the existence of potential tissue variants in rat lipoprotein lipase

Abstract

Lipoprotein lipases (LPL) isolated from rat cardiac muscle and bovine milk were each used as immunogens to produce polyclonal anti-LPL sera and two anti-LPL monoclonal antibodies. The immunological reactivities of these antibody sources with LPL purified from rat cardiac muscle, lung, adipose tissue, mammary gland and skeletal muscle were compared by an e.l.i.s.a. and by Western blotting. Differences between the immunoreactivities of LPL from the distinct tissue sources were revealed in both systems. A synthetic peptide with a sequence corresponding to the heparin-binding site of LPL (Ser-Arg-Thr-Asn-Thr-Lys-Val-Ser-Arg-Ile-Thr-Gly-Leu) was produced and used as an immunogen. The antiserum produced against the synthetic peptide was found to bind specifically to the region of the heparin-binding site, as determined by use of a competition e.l.i.s.a. In use against the five tissue LPL preparations, this antiserum revealed only minor variations between the tissue sources, compared with the hierarchy of reactivity observed when antibodies raised against the whole molecule were used. In combination with the outcome of previous studies on some of the physical properties of these preparations [Soteriou and Cryer (1993) Int. J. Biochem. 25, 1483-1490], the observations reported here on the distinct immunoreactivities exhibited by LPL prepared from the different tissue sources of a single species indicate the necessity to characterize fully the nature of these differences.

The response to fasting and refeeding reveals functional regulation of lipoprotein lipase proteoforms

“…First, on the basis of the well-described tissue-specific regulation of LPL, we investigated the distribution of LPL proteoforms in several rat tissues under basal conditions and observed different proteoform patterns in LPL from heart, skeletal muscle, epididymal WAT and BAT. This finding is consistent with previous studies reporting that LPL from different tissues has different properties in terms of enzyme kinetics, thermolability, specific activity and immunoreactivity, which suggested the existence of tissue-specific variants of the enzyme ( Fielding, 1976 ; Ben-Zeev et al, 1983 ; Soteriou and Cryer, 1993 ; Soteriou and Cryer, 1994 ). Importantly, the fact that tissues with different LPL regulation exhibit distinct patterns of LPL proteoforms suggests that different LPL proteoforms may have distinct functional properties.…”

Adrenergic stimulation of lipoprotein lipase gene expression in rat brown adipocytes differentiated in culture: mediation via β3- and α1-adrenergic receptors

“…The present observations highlight the interesting question of the tissue-specific adrenergic regulation of the expression of the LPL gene, with the contrasting effects of cAMP-elevating agents that occur in different tissues. There is only one gene for the enzyme [37,67], although tissue variants may exist [68] ; thus the differential expression must be regulated in the promoter region of the gene. The promoter is still not fully analysed and no functional cAMP response element (CRE) has been identified, although a CRE consensus sequence may occur at approx.…”