title: GSM5839924: Hi-C.alpha1; Homo sapiens; Hi-C
library_construction_protocol: Human islets were purchased from Prodo Labs (Cat# HIR-001). After receiving, the islets were well dispersed and washed with complete PIM(S) media (Prodo Labs, Cat# PIM-S001GMP) by centrifuging at 180g for 2 minutes.  The supernatant was removed with about 2-3ml of media left. The islet pellets were then gently resuspended in complete PIM(S) media, and transferred to a 6-well non-tissue culture treated plate. After recovering in a cell incubator for overnight, the islets were digested to single cells. Briefly, the islets were pelleted and washed with HBSS without Ca++/Mg++ (Sigma, Cat# H6648-1L), and then digested with Accutase (Life Technologies, Cat# A1110501) in a 6-well non-treated plate at 37ºC for about 5 minutes. The digested cells were filtered through a 40?m cell strainer to obtain single cells, and the cell number and viability were observed after washing twice with HBSS. To prepare for low input Hi-C, the single cells were firstly fixed with BD cytofix/ cytoperm buffer (BD, Cat# 51-2090KZ) for 20 minutes and washed with BD perm/ Wash buffer before stained with desired antibodies for alpha cells (BD Biosciences, BV421 mouse anti-glucagon, Cat# 565891) and beta cells (BD Biosciences, Alexa Flour 647 Mouse Anti-Insulin, Cat# 565689). The cells were sorted out using BD FACS ARIA II. We followed our previous easy Hi-C protocol to generate the eHi-C libraries. In order to make it compatible to low input sorted cells, we made a few changes. Briefly, about 20-30k sorted alpha or beta cells were applied for each library. Nuclei were extracted and digested with HindIII before proximity ligation. The chromatin ligates were then digested DpnII before constructing self-circles. The circuited DNAs were then linearized with a second digestion of HindIII. All the recovered DNAs were used to generate libraries. We followed the standard protocol to generate the libraries with modified Truseq adapters containing a regular sample index (i7) and a random fragment index (i5: NNNNNN).