Rabbit Anti-Human Cathepsin H (a.a. 71-170) Polyclonal antibody

Background: In our previous investigations of the role of the extracellular matrix (ECM) in promoting neurite growth we have observed that a permissive laminin (LN) substrate stimulates differential growth responses in subpopulations of mature dorsal root ganglion (DRG) neurons. DRG neurons expressing Trk and p75 receptors grow neurites on a LN substrate in the absence of neurotrophins, while isolectin B4-binding neurons (IB4(+)) do not display significant growth under the same conditions. We set out to determine whether there was an expression signature of the LN-induced neurite growth phenotype. Using a lectin binding protocol IB4(+) neurons were isolated from dissociated DRG neurons, creating two groups - IB4(+) and IB4(-). A small-scale microarray approach was employed to screen the expression of a panel of ECM-associated genes following dissociation (t=0) and after 24 hr culture on LN (t=24LN). This was followed by qRT-PCR and immunocytochemistry of selected genes. Results: The microarray screen showed that 36 of the 144 genes on the arrays were consistently expressed by the neurons. The array analyses showed that six genes had lower expression in the IB4+ neurons compared to the IB4-cells at t=0 (CTSH, Icam1, Itg beta 1, Lamb1, Plat, Spp1), and one gene was expressed at higher levels in the IB4(+) cells (Plaur). qRT-PCR was carried out as an independent assessment of the array results. There were discrepancies between the two methods, with qRT-PCR confirming the differences in Lamb1, Plat and Plaur, and showing decreased expression of AdamTs1, FN, and Icam in the IB4(+) cells at t=0. After 24 hr culture on LN, there were no significant differences detected by qRT-PCR between the IB4(+) and IB4(-) cells. However, both groups showed upregulation of Itg beta 1 and Plaur after 24 hr on LN, the IB4(+) group also had increased Plat, and the IB4(-) cells showed decreased Lamb1, Icam1 and AdamTs1. Further, the array screen also detected a number of genes (not subjected to qRT-PCR) expressed similarly by both populations in relatively high levels but not detectably influenced by time in culture (Bsg, Cst3, Ctsb, Ctsd, Ctsl, Mmp14, Mmp19, Sparc. We carried out immunohistochemistry to confirm expression of proteins encoded by a number of these genes. Conclusions: Our results show that 1B4(+) and IB4(-) neurons differ in the expression of several genes that are associated with responsiveness to the ECM prior to culturing (AdamTs1, FN, Icam1, Lamb1, Plat, Plaur). The data suggest that the genes expressed at higher levels in the IB4(-) neurons could contribute to the initial growth response of these cells in a permissive environment and could also represent a common injury response that subsequently promotes axon regeneration. The differential expression of several extracellular matrix molecules (FN, Lamb1, Icam) may suggest that the IB4(-) neurons are capable of maintaining /secreting their local extracellular environment which could aid in the regenerative process. Overall, these data provide new information on potential targets that could be manipulated to enhance axonal regeneration in the mature nervous system.

Over 40 susceptibility loci have been identified for type 1 diabetes (T1D). Little is known about how these variants modify disease risk and progression. Here, we combined in vitro and in vivo experiments with clinical studies to determine how genetic variation of the candidate gene cathepsin H (CTSH) affects disease mechanisms and progression in T1D. The T allele of rs3825932 was associated with lower CTSH expression in human lymphoblastoid cell lines and pancreatic tissue. Proinflammatory cytokines decreased the expression of CTSH in human islets and primary rat beta-cells, and overexpression of CTSH protected insulin-secreting cells against cytokine-induced apoptosis. Mechanistic studies indicated that CTSH exerts its antiapoptotic effects through decreased JNK and p38 signaling and reduced expression of the proapoptotic factors Bim, DP5, and c-Myc. CTSH overexpression also up-regulated Ins2 expression and increased insulin secretion. Additionally, islets from Ctsh(-/-) mice contained less insulin than islets from WT mice. Importantly, the TT genotype was associated with higher daily insulin dose and faster disease progression in newly diagnosed T1D patients, indicating agreement between the experimental and clinical data. In line with these observations, healthy human subjects carrying the T allele have lower beta-cell function, which was evaluated by glucose tolerance testing. The data provide strong evidence that CTSH is an important regulator of beta-cell function during progression of T1D and reinforce the concept that candidate genes for T1D may affect disease progression by modulating survival and function of pancreatic beta-cells, the target cells of the autoimmune assault.